JP2012204671A - Semiconductor light-emitting element - Google Patents

Abstract

Provided is a semiconductor light emitting element capable of improving luminous efficiency by suppressing laser oscillation in a Fabry-Perot mode with a simple configuration.
A semiconductor light emitting device including a semiconductor layer stack including a light emitting layer (active layer 104) formed above a substrate 101 and a light emitting end face 130a that emits light emitted from the light emitting layer. An optical waveguide 124 that confines and guides light emitted from the layer, and a region between the optical waveguide end surface 124a and the light output end surface 130a, which are end surfaces on the light output end surface side of the optical waveguide 124, and light from the optical waveguide end surface 124a. Up to the emission end face 130a, the optical waveguide 124 is provided with a separation area 127A that is an area through which light from the optical waveguide 124 passes through the main surface of the substrate 101 in a horizontal direction without substantially confining the light. It inclines with respect to the end surface 130a.
[Selection] Figure 1

Description

  The present invention relates to a semiconductor light emitting device, and more particularly to a superluminescent diode that emits light in the visible light region from violet to red.

  In addition to light sources for medical equipment such as optical coherence tomography (OCT) systems, in recent years, super luminescent has both high directivity and low coherence as a light source for image display devices such as projectors. Semiconductor light emitting devices such as diodes (SLD: Super Luminescent Diode) have been developed.

  The SLD is a semiconductor light emitting device using an optical waveguide similar to a semiconductor laser (LD), and spontaneous emission light generated by recombination of injected carriers is high due to stimulated emission while proceeding in the direction of the light emitting end face. The gain is amplified and emitted from the light emitting end face.

  In addition, unlike the LD, the SLD is configured to suppress the formation of an optical resonator due to end face reflection and to prevent laser oscillation in the Fabry-Perot mode. Therefore, the SLD has a structure in which the light emitting end face is inclined with respect to the waveguide, for example, thereby reducing the mode reflectivity and suppressing laser oscillation. Such an SLD exhibits an incoherent and broadband spectral shape as in a normal light emitting diode, and can obtain light emission with a narrow emission angle.

  On the other hand, a semiconductor light emitting device using a nitride semiconductor is realized as a light emitting device that emits light in the visible light region from ultraviolet to green, such as a light emitting diode. In recent years, SLDs using this nitride semiconductor have also been proposed.

  In such an SLD, in order to make the emitted light incoherent, a technique for reducing the reflectance of the light emitting end face is important. Hereinafter, the prior art described in Patent Document 1 and Patent Document 2 will be described in detail with reference to FIGS. 24 and 25.

  FIG. 24 is a perspective view of a semiconductor laser amplifier according to a first conventional example disclosed in Patent Document 1. In FIG. FIG. 25 is a perspective view of a semiconductor light emitting element according to a second conventional example disclosed in Non-Patent Document 1.

  As shown in FIG. 24, a semiconductor laser amplifier 1000 according to a first conventional example relates to a technique for suppressing a Fabry-Perot mode, and a waveguide 1012 is formed in a semiconductor region 1015 of a semiconductor body 1016 made of GaInAsP or the like. The waveguide 1012 is obliquely connected to the faces of the facets 1017 and 1018. Further, the facets 1017 and 1018 are provided with end cap portions 1010 and 1011 made of a material having a wider band gap than the semiconductor body 1016, thereby forming an incident end face 1013 and an exit end face 1014. .

  With this configuration, light incident on the waveguide 1012 from the incident end face 1013 is amplified by the semiconductor region 1015 and then refracted by the facet 1018 and then emitted from the surface 1019 to the outside. At this time, a part of the light is reflected by the surface 1019, but since the waveguide 1012 and the facet 1018 are connected obliquely, the reflected light is inclined with respect to the surface 1019 by the thickness of the terminal cap portion 1011. Propagate to. As a result, since the reflected light hardly returns to the waveguide 1012, even if light having a strong light output enters the waveguide 1012, the light is less likely to resonate in the Fabry-Perot mode inside the waveguide 1012. .

  On the other hand, the semiconductor light emitting device 2000 according to the second conventional example shown in FIG. 25 is an SLD using a nitride semiconductor, and a first cladding layer 2002 made of an AlGaN / GaN superlattice is formed on a GaN substrate 2001. A first guide layer 2003 made of Si-doped GaN, a multiple quantum well layer 2004 made of InGaN, a barrier layer 2006 made of AlGaN, a second guide layer 2005 made of Mg-doped GaN, and a second guide layer made of Mg-doped AlGaN. The cladding layer 2007 is formed by sequentially laminating.

Further, the second clad layer 2007 is etched to form a striped ridge portion (optical waveguide). A p-side contact electrode layer 2008 is formed on the surface of the ridge portion of the second cladding layer 2007 via an insulating layer 2010 made of SiO ₂ . On the other hand, an n-side contact electrode layer 2011 is formed on the opposite surface of the GaN substrate 2001.

  Carriers are injected by applying a voltage to the p-side contact electrode layer 2008 and the n-side contact electrode layer 2011. The carriers injected into the multiple quantum well layer 2004 are converted into light, amplified by the optical waveguide, and emitted from the light emitting end face.

  At this time, an oblique facet surface 2012 is formed on the light emitting end surface in order to reduce the reflectance. With this configuration, the light amplified in the waveguide is emitted to the outside without laser oscillation in the Fabry-Perot mode.

JP-A-3-030488

Appl. Phys. Lett. 081107 (95) 2009.

  In an SLD made of a nitride semiconductor that has been developed in recent years, the emission wavelength is 400 nm to 550 nm, and the wavelength in the visible light region is shortened. In such an SLD, in order to suppress the laser oscillation in the Fabry-Perot mode at the time of high light output operation, it is necessary to make the structure near the light emitting end face more precisely and to reduce the reflectance of the light emitting end face. .

  Specifically, in the structure in which the waveguide is inclined with respect to the light emitting end face as in the semiconductor light emitting device 2000 according to the second conventional example shown in FIG. 25, the flatness of the light emitting end face is reduced in order to reduce the reflectance. Therefore, it is necessary to reduce the minute unevenness of the light emitting end face generated when the light emitting end face is manufactured to a nano-order scale or less.

  Further, when the termination cap portion 1011 is provided in the light emitting portion as in the first conventional example shown in FIG. 24, the light absorption by the termination cap portion 1011 is made effective in order to make the above effect in the termination cap portion 1011 effective. It is necessary to reduce the thickness of the terminal cap portion 1011 to the micron order.

  However, it is not easy to reduce the minute unevenness of the light emitting end face to a nano-order scale or less. Further, it is not easy to increase the thickness of the end cap to the micron order and reduce the light absorption.

  The present invention has been made in view of these points, and an object of the present invention is to provide a semiconductor light emitting device capable of improving the luminous efficiency by suppressing the Fabry-Perot mode laser oscillation with a simple configuration. To do.

  In order to achieve the above object, one aspect of a semiconductor light emitting device according to the present invention is a semiconductor layer laminate having a light emitting layer formed above a substrate and a light emitting end face that emits light emitted from the light emitting layer. An optical waveguide that confines and guides light emitted from the light emitting layer, and a region between the optical waveguide end face that is an end face of the optical waveguide on the light emission end face side and the light emission end face A separation region that is a region that allows light from the optical waveguide to pass through without substantially confining in a horizontal direction with the main surface of the substrate from the optical waveguide end surface to the light emitting end surface, The optical waveguide end face is inclined with respect to the light emitting end face.

  According to this aspect, since the separation region is provided, the light emitted from the end face of the optical waveguide propagates to the light exit end face inclined with respect to the optical waveguide and is emitted to the outside from the light exit end face. Most of the light reflected at the end face does not return to the optical waveguide. Thereby, since the laser oscillation in the Fabry-Perot mode can be suppressed, the light emission efficiency can be improved.

  Furthermore, in one aspect of the semiconductor light emitting device according to the present invention, the optical waveguide and the isolation region are preferably formed of the same semiconductor layer stack.

  Thereby, the light emitted from the end face of the optical waveguide can be propagated without loss on the end face of the light exit. For this reason, the luminous efficiency of the semiconductor light emitting device can be improved.

  Furthermore, in one aspect of the semiconductor light emitting device according to the present invention, it is preferable that a distance between the end face of the optical waveguide and the end face of the light emission is 1 μm or more.

  Thereby, the laser oscillation in the Fabry-Perot mode can be suppressed, and the light emission efficiency of the semiconductor light emitting element can be improved.

  Further, in one aspect of the semiconductor light emitting device according to the present invention, the semiconductor light emitting device includes a contact electrode formed above the optical waveguide, and an end portion of the contact electrode on the light emitting end surface side includes the optical waveguide end surface and the light emitting surface. It is preferable to extend to the end face.

  Thereby, the light radiate | emitted from the optical-waveguide end surface can be propagated with a small loss between light emission end surfaces. For this reason, the luminous efficiency of the semiconductor light emitting device can be improved.

  Furthermore, in one aspect of the semiconductor light emitting device according to the present invention, a part or all of the width of the contact electrode formed between the end face of the optical waveguide and the end face of the light emission is formed above the optical waveguide. The contact electrode is preferably wider than the width of the contact electrode.

  Thereby, the light radiate | emitted from the optical-waveguide end surface can be propagated with a small loss between light emission end surfaces. For this reason, the luminous efficiency of the semiconductor light emitting device can be improved.

  Furthermore, in one aspect of the semiconductor light emitting device according to the present invention, the width of the contact electrode formed between the waveguide end face and the light emitting end face gradually increases from the optical waveguide end face toward the light emitting end face. It is preferable to spread.

  Thereby, the light emitted from the end face of the optical waveguide can further suppress the loss between the light exit end face.

  Furthermore, in one aspect of the semiconductor light emitting device according to the present invention, it is preferable that the light emitting end face is a cleavage plane.

  Thereby, the light emission end face of the semiconductor light emitting element can be easily manufactured.

  Furthermore, in one aspect of the semiconductor light emitting device according to the present invention, it is preferable that a step groove formed so as to cut out the semiconductor layer stack is provided, and the light emitting end face is an inner surface of the step groove.

  Thereby, the light emission end face of the semiconductor light emitting element can be easily manufactured.

  Furthermore, in one aspect of the semiconductor light emitting device according to the present invention, the step groove is preferably formed by etching.

  Thereby, the light emission end face of the semiconductor light emitting element can be easily manufactured.

  Furthermore, in one aspect of the semiconductor light emitting device according to the present invention, it is preferable that a substrate step portion formed on the substrate is provided in the isolation region or a region in the vicinity thereof.

  Thereby, since the band gap of the light emitting layer in the separation region can be widened, the light emitted from the end face of the optical waveguide can be propagated with a small loss to the end face of the light exit. For this reason, the luminous efficiency of the semiconductor light emitting device can be improved.

  Furthermore, in one aspect of the semiconductor light emitting device according to the present invention, it is preferable that a part or all of the isolation region is a region that transmits light without substantially absorbing light from the optical waveguide.

  According to the semiconductor light emitting device of the present invention, the light emission efficiency of the semiconductor light emitting device can be improved.

1 is a top view of a semiconductor light emitting element according to a first embodiment of the present invention. It is sectional drawing of the semiconductor light-emitting device which concerns on the 1st Embodiment of this invention in the A-A 'line | wire of FIG. It is sectional drawing of the semiconductor light-emitting device which concerns on the 1st Embodiment of this invention in the B-B 'line | wire of FIG. It is sectional drawing of the semiconductor light-emitting device which concerns on the 1st Embodiment of this invention in the C-C 'line | wire of FIG. It is the elements on larger scale in the front end surface vicinity part of the semiconductor light-emitting device concerning the 1st Embodiment of this invention. It is a figure which shows the structure of the light-projection end surface (no nano order unevenness | corrugation) vicinity in SLD which concerns on the comparative example 1 which does not have an isolation region. It is a figure which shows the structure of the light-projection end surface (with nano order unevenness | corrugation) vicinity in SLD which concerns on the comparative example 2 without a isolation | separation area | region. It is a figure which shows the structure of the light emission end surface vicinity in the semiconductor light-emitting device concerning the 1st Embodiment of this invention. It is a schematic diagram for calculating the distance L of the isolation region in the semiconductor light emitting device according to the first embodiment of the present invention. It is a figure for demonstrating the end surface angle dependence of the reflectance in SLD which concerns on the comparative example 1, and the semiconductor light-emitting device concerning the 1st Embodiment of this invention. It is a figure for demonstrating the process of forming the recessed part and level | step difference groove | channel in the manufacturing method of the semiconductor light-emitting device concerning the 1st Embodiment of this invention. It is a figure for demonstrating the process of forming the block layer and p side contact electrode in the manufacturing method of the semiconductor light-emitting device concerning the 1st Embodiment of this invention. It is a figure for demonstrating the 1st division | segmentation process in the manufacturing method of the semiconductor light-emitting device concerning the 1st Embodiment of this invention. It is a figure for demonstrating the 2nd division | segmentation process in the manufacturing method of the semiconductor light-emitting device concerning the 1st Embodiment of this invention. It is a figure which shows the current-light output characteristic and the current-slope efficiency characteristic in SLD which concerns on the comparative example 2. It is a figure which shows the electric current-light output characteristic and the electric current-slope efficiency characteristic in the semiconductor light-emitting device concerning the 1st Embodiment of this invention. FIG. 6 is a top view of a semiconductor light emitting element according to a second embodiment of the present invention. It is sectional drawing of the same semiconductor light-emitting device in the B-B 'line | wire of FIG. 9A. It is the elements on larger scale in the front-end surface vicinity part of the semiconductor light-emitting device concerning the 2nd Embodiment of this invention. FIG. 5 is a partially enlarged view of a semiconductor light emitting device (SLDs according to Comparative Examples 1 and 2 shown in FIGS. 4A and 4B) in a case where the end face of the optical waveguide and the end face of the light emission are on the same plane. It is the elements on larger scale of the semiconductor light-emitting device (this invention 1) in case the optical waveguide end surface and the light emission end surface are isolate | separated by the isolation | separation area | region. A semiconductor light emitting device in which the optical waveguide end face and the light emitting end face are separated by a separation region, and the contact electrode end face of the p-side contact electrode is at a position shifted from the optical waveguide end face toward the light emitting end face It is the elements on larger scale of invention 2). 11A, 11B, and 11C are diagrams illustrating a relationship among a separation region, a separation distance, and a slope efficiency (when the optical output is 50 mW) in each of the semiconductor light emitting devices illustrated in FIGS. 11A, 11B, and 11C. It is the elements on larger scale of the light-emitting end surface vicinity of the semiconductor light-emitting device which concerns on the modification 1 of the 2nd Embodiment of this invention. It is the elements on larger scale near the light-projection end surface of the semiconductor light-emitting device concerning the modification 2 of the 2nd Embodiment of this invention. FIG. 6 is a top view of a semiconductor light emitting element according to a third embodiment of the present invention. FIG. 15B is a cross-sectional view of the semiconductor light emitting element according to the third embodiment of the present invention taken along line B-B ′ of FIG. 15A. It is the elements on larger scale in the front end surface vicinity part of the semiconductor light-emitting device concerning the 3rd Embodiment of this invention. It is a figure for demonstrating the manufacturing method of the semiconductor light-emitting device which concerns on the 3rd Embodiment of this invention. FIG. 6 is a top view of a semiconductor light emitting element according to a fourth embodiment of the present invention. It is sectional drawing of the semiconductor light-emitting device which concerns on the 4th Embodiment of this invention in the A-A 'line | wire of FIG. It is sectional drawing of the semiconductor light-emitting device which concerns on the 4th Embodiment of this invention in the B-B 'line | wire of FIG. It is the elements on larger scale in the front end surface vicinity part of the semiconductor light-emitting device concerning the 4th Embodiment of this invention. It is a schematic diagram for demonstrating the manufacturing method of the semiconductor light-emitting device concerning the 4th Embodiment of this invention. It is the elements on larger scale in the front end surface vicinity part of the semiconductor light-emitting device which concerns on the modification of the 4th Embodiment of this invention. FIG. 6 is a top view of a semiconductor light emitting element according to a fifth embodiment of the present invention. It is sectional drawing of the semiconductor light-emitting device which concerns on the 5th Embodiment of this invention in the A-A 'line | wire of FIG. 23A. FIG. 24B is a cross-sectional view of the semiconductor light-emitting element according to the fifth embodiment of the present invention taken along the line B-B ′ of FIG. 23B. 10 is a perspective view of a semiconductor laser amplifier according to a first conventional example disclosed in Patent Document 1. FIG. It is a perspective view of the semiconductor light-emitting device concerning the 2nd prior art example indicated by nonpatent literature 1.

  Hereinafter, embodiments according to the present invention will be described with reference to the drawings. In addition, each embodiment shown below is an example, Comprising: This invention is not limited to these embodiment.

  In each figure, c, a, and m indicate the plane orientation of the hexagonal GaN-based crystal. Here, c represents a normal vector whose plane orientation is the (0001) plane, that is, the c axis, and a represents a normal vector of the (11-20) plane and its equivalent plane, that is, the a axis. , M represents the normal vector of the (1-100) plane and its equivalent plane, that is, the m-axis. In the present specification, the minus sign “−” attached to the Miller index in the plane orientation represents the inversion of one index following the minus sign for convenience.

(First embodiment)
First, the configuration of the semiconductor light emitting device 100 according to the first embodiment of the present invention will be described with reference to FIGS. 1, 2A, 2B, and 2C. FIG. 1 is a top view of a semiconductor light emitting device 100 according to the first embodiment of the present invention. 2A is a cross-sectional view of the semiconductor light-emitting element taken along line AA ′ in FIG. 1, FIG. 2B is a cross-sectional view of the semiconductor light-emitting element taken along line BB ′, and FIG. It is sectional drawing of the same semiconductor light-emitting device in line '.

The semiconductor light emitting device 100 according to the first embodiment of the present invention is an SLD including a semiconductor layer stack including an n-type semiconductor layer, a light emitting layer, and a p-type semiconductor layer and made of a nitride semiconductor. As shown, the semiconductor layer stack includes a front end surface 140a that is an element end surface on the side where light emitted from the light emitting layer is emitted to the outside of the element and a rear end surface 140b that is an element end surface that reflects light guided inside the element. Have On the rear end surface 140b, for example, a high reflectivity layer 150 made of a dielectric multilayer film such as SiO ₂ / ZrO ₂ is laminated.

  As shown in FIGS. 2A to 2C, the semiconductor light emitting device 100 according to this embodiment includes an n-type made of n-type AlGaN doped with, for example, Si on a substrate 101 made of an n-type GaN substrate or an n-type SiC substrate. The clad layer 102 (first clad layer), for example, an n-type light guide layer 103 (first light guide layer) made of n-type GaN doped with Si, for example, an InGaN quantum well layer and a GaN quantum barrier layer alternately An active layer (light emitting layer) 104 having a multiple quantum well structure, for example, a p-type light guide layer 105 (second light guide layer) made of p-type GaN doped with Mg, for example, an Al composition doped with Mg An electron barrier layer 106 made of p-type AlGaN having a high ratio and a p-type clad layer 107 (second clad layer) made of p-type AlGaN doped with Mg were sequentially laminated. Than is.

  As shown in FIG. 2A, two concave portions 125 are formed on the surface of the p-type cladding layer 107, and a convex shape having a predetermined ridge width (stripe width) is sandwiched between the two concave portions 125. The ridge portion 107a is formed. The ridge portion 107a is a refractive index waveguide type optical waveguide 124 that guides light emitted from the light emitting layer 104 by providing a refractive index distribution by the convex structure of the ridge portion 107a. As shown in FIG. In FIG.

  As shown in FIGS. 1 and 2A, the regions where the recess 125 is formed are the recess regions 125a and 125b, and the region between the recess region 125a and the recess region 125b where the optical waveguide 124 is formed. Let it be an optical waveguide region 124A. In addition, regions other than the optical waveguide region 124A and the recessed regions 125a and 125b in the ridge width direction are referred to as pedestal regions 126a and 126b.

As shown in FIG. 2A, the surface of the p-type cladding layer 107 is covered with a block layer 109 made of an insulating film formed to have an opening on the ridge portion 107a. For example, the block layer 109 made of an insulating material such as SiO ₂ covers other than the top of the ridge 107a (optical waveguide 124).

  Further, a p-side contact electrode 108 made of, for example, a Pd / Pt multilayer metal film is formed in the opening on the ridge portion 107a, and the p-type cladding layer 107 and the p-side contact electrode 108 are electrically connected to each other in the ridge portion 107a. Connected.

  Further, a wiring electrode 110 is formed on the p-side contact electrode 108 and the block layer 109. On the other hand, an n-side contact electrode 111 made of a multilayer metal film such as Ti / Pt / Au is formed on the back surface of the substrate 101.

  As shown in FIGS. 1 and 2C, a step groove 130 is formed by etching in the vicinity of the front end surface 140a, and light emitted from the light emitting layer 104 is emitted to the outside of the element by the inner surface of the step groove 130. A light emitting end face 130a which is an end face is configured. The light emitting end surface 130a is an extremely low reflection surface configured to radiate light propagating through the optical waveguide 124 to the outside of the device, and is formed so as to form a predetermined angle with respect to the front end surface 140a.

  Furthermore, the light emitting end face 130a is configured to be inclined with respect to the optical waveguide end face 124a that is the end face on the light emitting end face 130a side (front end face 140a side) of the optical waveguide 124, and is normal to the light emitting end face 130a. Is inclined at a constant angle with respect to the extension axis (stripe direction axis) of the optical waveguide 124.

  The step groove 130 is an etching end face groove formed at a depth from the p-type cladding layer 107 to at least the n-type cladding layer 102. Further, as shown in FIG. 2C, the surface of the step groove 130 exposed by etching is covered with a block layer 109. A region where the step groove 130 is formed is referred to as a step groove region 130A.

  Furthermore, as shown in FIGS. 1, 2B, and 2C, the semiconductor light emitting device 100 according to the present embodiment is provided with a region where the ridge portion 107a is not formed on the front end face 140a side. That is, as shown in FIG. 1, the semiconductor light emitting device 100 according to this embodiment has a separation region 127A that is a region between an optical waveguide end surface 124a (not shown) of the optical waveguide 124 and the light emitting end surface 130a. The separation region 127A separates the optical waveguide end surface 124a and the light emitting end surface 130a of the optical waveguide 124 by separating the optical waveguide end surface 124a and the light emitting end surface 130a of the optical waveguide 124 by a predetermined distance. In the separation region 127A, between the optical waveguide end surface 124a and the light emitting end surface 130a, the light traveling from the optical waveguide 124 to the light emitting end surface 130a is substantially in the lateral direction (the direction horizontal to the main surface of the substrate). It propagates in the separation region 127A where there is no optical confinement. Such a separation region 127A is configured such that, for example, a part or all of the separation region 127A is a region that transmits light from the optical waveguide 124 without substantially absorbing it. As shown in FIGS. 1 and 2A to 2C, in this embodiment, the optical waveguide region 124A and the isolation region 127A are formed of the same semiconductor layer stack, that is, a stack made of the same semiconductor material. ing.

  Hereinafter, a detailed structure of the front portion (near the front end surface 140a) of the semiconductor light emitting device 100 according to the present embodiment will be described with reference to FIG. FIG. 3 is a partially enlarged view of a portion near the front end face of the semiconductor light emitting device according to the first embodiment of the present invention.

  As shown in FIG. 3, the optical waveguide end surface 124 a of the optical waveguide 124 is separated from the light emitting end surface 130 a that is the side wall of the step groove 130 by a predetermined distance. The separation region 127A is a region where the concave portion 125 is not formed, that is, a region where the optical waveguide 124 (ridge portion 107a) is not formed in this embodiment. Further, the contact electrode end surface 108a, which is the end surface on the light emitting end surface 130a side (front end surface 140a side) of the p-side contact electrode 108 for injecting carriers into the optical waveguide 124, is similar to the light emitting end surface 130a. The configuration is a predetermined distance away.

  Next, the operation of the semiconductor light emitting device 100 according to this embodiment will be described with reference to FIGS. 4A, 4B, and 4C. FIG. 4A is a diagram showing a configuration in the vicinity of a light emitting end face (no nano-order irregularities) in the SLD according to Comparative Example 1 having no separation region. FIG. 4B is a diagram showing a configuration in the vicinity of a light emission end face (with nano-order irregularities) in an SLD according to Comparative Example 2 having no separation region. FIG. 4C is a diagram showing a configuration in the vicinity of the light emitting end face of the semiconductor light emitting device according to the first embodiment of the present invention.

  As shown in FIG. 4A, in the case of the SLD according to Comparative Example 1, when the propagating light 170 propagating through the optical waveguide 124 is emitted from the optical waveguide 124, the propagating light 170 is reflected by the light emitting end face 130a. Since the stripe direction of the light 124 and the light emitting end face 130 a have a predetermined angle, most of the reflected light 171 does not return to the optical waveguide 124. For this reason, theoretically, it is possible to reduce the ratio of light returning to the optical waveguide (mode reflectivity) to the extent that laser oscillation in the Fabry-Perot mode does not occur.

  However, in the actually produced SLD, as shown in FIG. 4B, since the light emitting end face 130a has nano-order minute irregularities, the propagating light 170 is reflected by the light emitting end face 130a (reflected). Light 171) and light scattered by minute unevenness (scattered light 172, 173). As a result, a part of the propagation light 170 (scattered light 173) is fed back to the optical waveguide 124. Therefore, unlike an SLD having an ideal end face as in Comparative Example 1, the mode reflectance is increased. As a result, laser oscillation in the Fabry-Perot mode is likely to occur. In particular, when the light output of the semiconductor light-emitting element becomes high during high-power operation, Fabry-Perot mode laser oscillation tends to occur.

  On the other hand, as shown in FIG. 4C, in the semiconductor light emitting device 100 according to this embodiment, since the separation region 127A is provided between the optical waveguide end face 124a and the light emitting end face 130a, a minute amount is formed on the light emitting end face 130a. Even if there are irregularities, the separation region 127A without the optical waveguide 124 can prevent the scattered light 172 and 173 scattered by the minute irregularities from returning to the optical waveguide 124.

  Here, a preferable range of the distance L of the separation region 127A will be described with reference to FIG. FIG. 5 is a schematic diagram for calculating the distance L of the isolation region in the semiconductor light emitting device according to the first embodiment of the present invention. In FIG. 5, the light returning to the optical waveguide is calculated when the light emitted from the optical waveguide 124 propagates straight and is reflected by the light emitting end face 130a.

  In FIG. 5, when the width of the optical waveguide 124 is W, the distance (length) of the separation region 127A is L, and the inclination angle of the light emitting end face 130a is θ, the condition of L> W / tan (2θ) is satisfied. Thus, the reflected light 171 reflected does not return to the optical waveguide 124. For example, when W = 1.5 μm and θ = 10 °, it can be seen that L> about 4.1 μm. In this case, since the direction of the scattered light is distributed around the reflected light, the distance L of the separation region 127A is sufficiently larger than 4.1 μm to effectively release the scattered light out of the optical waveguide 124. A large distance is desirable.

  The distance between the optical waveguide end face 124a and the light exit end face 130a is preferably at least 1 μm or more. As a result, the light emitted from the optical waveguide end face 124 a is emitted to the outside from the light outgoing end face 130 a, while most of the light reflected on the light outgoing end face 130 a does not return to the optical waveguide 124. Thereby, since the laser oscillation in the Fabry-Perot mode can be suppressed, the light emission efficiency of the semiconductor light emitting element can be improved.

  Next, the dependency of the reflectance on the end face angle in the SLD according to Comparative Example 1 shown in FIG. 4A and the semiconductor light emitting device 100 according to the first embodiment of the present invention shown in FIG. 4C will be described with reference to FIG. . FIG. 6 is a diagram for explaining the dependency of the reflectance on the end face angle in the SLD according to Comparative Example 1 and the semiconductor light emitting device according to the first embodiment of the present invention.

  In FIG. 6, the dotted curve illustrated as “Comparative Example 1A” represents the dependence of the reflectance on the end face angle when the wavelength is long in the SLD according to Comparative Example 1 illustrated in FIG. 4A. Here, whether the wavelength is long or short is generally distinguished by whether the wavelength is 500 nm to 1 μm or more, or less, and the effect is determined by the magnitude relationship between the wavelength length and the minute unevenness of the light emitting end face 130a. Is. Further, the dashed-dotted curve illustrated as “Comparative Example 1B” represents the dependence of the reflectance on the end face angle when the wavelength is short in the SLD according to Comparative Example 1 shown in FIG. 4A. Also, the solid curve illustrated as “Invention 1” represents the dependence of the reflectance on the end face angle in the case of the semiconductor light emitting device according to the first embodiment of the present invention shown in FIG. 4C. In FIG. 6, a curve indicated by a broken line as “plane wave” represents the angle dependency of the reflectance of the plane wave. In “Comparative Example 1A”, “Comparative Example 1B”, and “Invention 1”, a guided mode is considered.

  As shown in FIG. 6, it can be seen that the reflectance can be reduced by providing the separation region 127A as in the present embodiment. Thus, in this embodiment, since the effective reflectance in the light emission end surface 130a can be reduced, the laser oscillation in the Fabry-Perot mode can be suppressed.

  Although not shown, in the SLD in which minute irregularities are formed on the light emitting end face by processing such as dry etching as shown in FIG. 4B, the reflectance in the optical waveguide increases as the wavelength is shorter.

  Next, a method for manufacturing the semiconductor light emitting device 100 according to the first embodiment of the present invention will be described with reference to FIGS. 7A to 7D. 7A to 7D are views for explaining each step in the method for manufacturing the semiconductor light emitting element according to the first embodiment of the present invention.

  First, on a substrate 101 made of, for example, a GaN substrate, a semiconductor laminated film made of a nitride semiconductor layer laminated body as shown in FIGS. 2A to 2C by using a metal organic chemical vapor deposition (MOCVD) method. Is deposited.

  First, on an unillustrated GaN layer doped with Si, for example, an n-type cladding layer 102 made of AlGaN doped with Si, for example, and an n-type light guide layer 103 made of GaN doped with Si, for example, An active layer 104 having a multiple quantum well structure in which the quantum well layer is InGaN and the barrier layer is GaN, for example, a p-type light guide layer 105 made of Mg-doped GaN, for example, a p-type clad layer 107 made of Mg-doped AlGaN. Films are continuously formed.

Subsequently, as shown in FIG. 7A, a recess 125 and a step groove 130 are formed at predetermined positions on the surface of the wafer 190. Specifically, after a mask material such as SiO ₂ is formed on the surface of the wafer 190, a pattern corresponding to the concave portion 125 is patterned at a predetermined position using a resist on the surface. Thereafter, SiO ₂ is subjected to predetermined patterning using, for example, a fluorine-based gas. Thereafter, the concave portion 125 is formed using, for example, a chlorine-based gas. Subsequently, after the SiO ₂ mask remaining in the etching is removed with an etchant such as hydrofluoric acid, a mask material such as SiO _{2 is} formed again on the surface, and a pattern corresponding to the step groove 130 is formed in the same manner. Thereafter, the step groove 130 is formed with a chlorine-based gas.

Thereafter, the SiO ₂ mask remaining in the etching is removed with an etchant such as hydrofluoric acid, and then, as shown in FIG. 7B, a block layer 109 made of an insulating film such as SiO ₂ is formed on the entire surface. Thereafter, patterning with a photoresist is performed at a predetermined position on the optical waveguide 124, and the block layer 109 only at the predetermined position is removed by wet etching using hydrofluoric acid or the like to form an opening. Continuously, a p-side contact electrode 108 made of, for example, Pd / Pt is formed in the opening by lift-off or the like, and then annealed at, for example, about 400 ° C. to make an electrical ohmic connection with the p-type cladding layer 107.

Subsequently, as shown in FIG. 7C, a resist pattern corresponding to the wiring electrode 110 made of, for example, Ti / Pt / Au is formed, and the wiring electrode 110 is formed again by lift-off. Thereafter, although not shown, after the back surface of the substrate 101 is polished by a predetermined thickness, a metal film made of, for example, Ti / Pt / Au is deposited on the back surface side by vapor deposition to form the n-side contact electrode 111. Then, for example, after separation by cleavage in the first dividing line 161 shown in FIG. 7C, as shown in FIG. 7D, for example, a dielectric multilayer film made of SiO ₂ / ZrO ₂ is sputtered on the rear end surface 140b of the element. The high reflectivity layer 150 is formed by forming a film. Thereafter, as shown in the figure, the semiconductor light emitting device 100 can be manufactured by performing element separation by laser dicing or the like along the second division line 162.

  Next, characteristics of the semiconductor light emitting device manufactured by the above manufacturing method will be described with reference to FIGS. 8A and 8B. FIG. 8A is a diagram showing current-light output characteristics and current-slope efficiency characteristics in the SLD according to Comparative Example 2. FIG. 8B is a diagram showing current-light output characteristics and current-slope efficiency characteristics in the semiconductor light-emitting device (present invention 1) according to the first embodiment of the present invention.

  As shown in FIGS. 8A and 8B, the semiconductor light emitting device 100 according to the first embodiment of the present invention has a slope efficiency Se (W / A) increased by about 40% compared to the SLD according to the comparative example 2. It can be seen that laser oscillation in the Fabry-Perot mode is suppressed. From this result, even in a semiconductor light emitting device having minute irregularities on the light emitting end face, the emission efficiency and the light output are improved by providing the separation region 127A between the optical waveguide end face and the light emitting end face. I understand.

  As described above, according to the semiconductor light emitting device 100 according to the first embodiment of the present invention, since the laser oscillation in the Fabry-Perot mode can be suppressed by providing the isolation region 127A, the light emission efficiency and the light output are improved. can do.

(Second Embodiment)
Next, the configuration of the semiconductor light emitting device 200 according to the second embodiment of the present invention will be described with reference to FIGS. 9A and 9B. FIG. 9A is a top view of the semiconductor light emitting device according to the second embodiment of the present invention, and FIG. 9B is a cross-sectional view of the semiconductor light emitting device taken along the line BB ′ of FIG. 9A. In FIGS. 9A and 9B, the same components as those shown in FIGS. 1 and 2A to 2C are denoted by the same reference numerals and description thereof is omitted, and the present embodiment is different from the first embodiment. The explanation will be focused on.

  As shown in FIGS. 9A and 9B, in the semiconductor light emitting device 200 according to the second embodiment of the present invention, as in the first embodiment, recessed regions 225a and 225b, which are regions in which recessed portions are formed, and a pedestal An optical waveguide 224 is formed by the regions 226a and 226b.

  A p-side contact electrode 208 is formed in the opening of the block layer 209 on the ridge portion (optical waveguide 224) of the p-type cladding layer 107.

  In this embodiment, as shown in FIG. 9A, the end portion on the light emitting end face 130a side of the p-side contact electrode 208 extends between the optical waveguide end face 224a and the light emitting end face 130a of the optical waveguide 224. The contact electrode end surface 208a, which is the end surface on the light emitting end surface 130a side of the p-side contact electrode 208, extends beyond the optical waveguide 224 (ridge portion), that is, in a region where the recessed regions 225a and 225b are not formed. To position. As described above, in this embodiment, the p-side contact electrode 208 is formed so that the contact electrode end surface 208a of the p-side contact electrode 208 is located a predetermined distance away from the light emitting end surface 130a.

  Hereinafter, the detailed configuration of the vicinity of the front end surface 140a of the semiconductor light emitting device 200 according to the present embodiment will be described with reference to FIG. FIG. 10 is a partially enlarged view of a portion near the front end face of the semiconductor light emitting device according to this embodiment.

  As shown in FIG. 10, also in the present embodiment, as in the first embodiment, a separation region 227A is formed between the optical waveguide end face 224a and the light emitting end face 130a.

  However, in the present embodiment, the contact electrode end face 208a is formed in the separation region 227A, and the separation region 227A in the present embodiment is configured by the first separation region 227A1 and the second separation region 227A2. . The first isolation region 227A1 is a region where the optical waveguide 224 is not formed and a region where the p-side contact electrode 208 is formed. The second isolation region 227A2 is a region where neither the p-side contact electrode 208 nor the optical waveguide 224 is formed.

  Next, effects of the semiconductor light emitting device 200 according to the second embodiment of the present invention will be described with reference to FIGS. 11A to 11C and FIG. FIG. 11A is a partially enlarged view of the semiconductor light emitting device when the optical waveguide end face 224a and the light emitting end face 130a are on the same plane, and the SLD (Comparative Example) according to Comparative Examples 1 and 2 shown in FIGS. 4A and 4B. It corresponds to. FIG. 11B is a partially enlarged view of the semiconductor light emitting device when the optical waveguide end surface 224a and the light emitting end surface 130a are separated by the separation region, and the semiconductor light emitting device according to the first embodiment of the present invention (the present invention). This corresponds to 1). In FIG. 11C, the optical waveguide end face 224a and the light emitting end face 130a are separated by the separation region, and the contact electrode end face 208a of the p-side contact electrode 208 is shifted to the light emitting end face 130a side from the optical waveguide end face 224a. It is the elements on larger scale of the semiconductor light emitting element in the case of being in a position, and is equivalent to the semiconductor light emitting element (Invention 2) concerning the 2nd embodiment of the present invention. FIG. 12 is a diagram showing the relationship between the separation distance D of the separation region 227A and the slope efficiency (Se) in each of the semiconductor light emitting devices shown in FIGS. 11A, 11B, and 11C. Note that the slope efficiency in FIG. 12 is obtained when the light output is 50 mW.

  In the semiconductor light emitting device shown in FIG. 11B, compared to the semiconductor light emitting device shown in FIG. 11A, the optical waveguide 224 is eliminated in the isolation region 227A (the lateral confinement is eliminated), so that the mode reflectance into the optical waveguide 224 is lowered. be able to. However, in this case, the separation region 227A absorbs light because there is no current injection, and if the separation distance D (length) of the separation region 227A becomes too long, a light absorption loss increases and efficiency decreases.

  On the other hand, as shown in FIG. 11C, the p-side contact electrode 208 in the separation region 227A exists by extending the p-side contact electrode 208 to a part of the separation region 227A and performing current injection. The first separation region 227A1 that is a region to be formed can be a gain waveguide type optical waveguide. Thereby, since the light absorption loss in the separation region 227A can be reduced, it is possible to prevent the light emission efficiency from being lowered.

  Specifically, as shown in FIG. 12, the slope efficiency in the semiconductor light emitting device (comparative example) shown in FIG. 11A was 1.0 [W / A], but the first embodiment shown in FIG. In such a semiconductor light emitting device (present invention 1), the slope efficiency (Se) increases up to a separation distance D of 5 μm. However, it can be seen that in the first aspect of the invention, when the separation distance D is 5 μm or more, the slope efficiency is saturated and begins to decrease.

  On the other hand, in the semiconductor light emitting device (Invention 2) according to the second embodiment shown in FIG. 11C, the slope efficiency increases monotonously in the range where the separation distance D is up to 20 μm. It can be seen that the light emission loss can be improved with less light absorption loss than the first aspect.

  In FIG. 12, the distance d of the second separation region 227A2 in the second aspect of the present invention is 3 μm.

(Modification 1)
Next, a semiconductor light emitting device 201 according to Modification 1 of the second embodiment of the present invention will be described with reference to FIG. FIG. 13 is a partially enlarged view of the vicinity of the light emitting end face of the semiconductor light emitting device according to Modification 1 of the second embodiment of the present invention. In this modification, the description of the same components as those of the second embodiment shown in FIG. 10 will be omitted, and different portions will be mainly described.

  As shown in FIG. 13, in the semiconductor light emitting device 201 according to this modification, the p-side contact electrode 208 is further extended compared to the second embodiment, and the p-side contact electrode 208 is connected to the light emitting end face 130a. Yes. That is, the p-side contact electrode 208 is extended by the separation distance of the separation region 227A, and the contact electrode end face 208a of the p-side contact electrode 208 is coincident with the light emitting end face 130a.

  Next, a method for manufacturing the semiconductor light emitting device 201 according to this modification will be described focusing on the vicinity of the light emitting end face. Note that the manufacturing method according to the present modification is almost the same as that of the second embodiment, and therefore only different parts will be described.

In this modification, for the optical waveguide 224, the p-side contact electrode 208, and the step groove 130, the p-side contact electrode 208 is formed after the step groove 130 is formed. Then, after forming the p-side contact electrode 208, an etching mask such as SiO ₂ is formed, and the step groove 130 is formed by etching the vicinity of the front end surface 140a of the semiconductor layer stack including a part of the p-side contact electrode 208. . Thereby, the semiconductor light emitting device 201 according to this modification can be manufactured.

  As described above, according to the semiconductor light emitting device 201 according to the present modification, the p-side contact electrode 208 is connected to the light emitting end face 130a, so that the light absorption loss can be completely eliminated. Thereby, the light emission efficiency can be further improved as compared with the second embodiment.

(Modification 2)
Next, a semiconductor light emitting element 202 according to Modification 2 of the second embodiment of the present invention will be described with reference to FIG. FIG. 14 is a partially enlarged view of the vicinity of the light emitting end face of the semiconductor light emitting device according to Modification 2 of the second embodiment of the present invention. Note that in this modification as well, the description of the same configuration as that of the second embodiment shown in FIG.

  As shown in FIG. 14, in the semiconductor light emitting device 202 according to this modification, the electrode width of the p-side contact electrode 208 is such that the first electrode width 208W1 in the optical waveguide region 224A and the second electrode width 208W2 in the contact electrode end surface 208a This is a two-stage configuration. That is, part or all of the width of the p-side contact electrode 208 in the isolation region 227A between the optical waveguide end surface 224a and the light emitting end surface 130a is wider than the width of the p-side contact electrode 208 in the optical waveguide region 224A. It is configured as follows.

  Further, in this modification, the electrode width of the p-side contact electrode 208 in the isolation region 227A is formed so as to gradually widen from the optical waveguide end face 224a toward the contact electrode end face 208a. That is, the p-side contact electrode 208 is formed such that the electrode width of the p-side contact electrode 208 gradually increases in the isolation region 227A.

  According to the semiconductor light emitting device 202 according to this modification, the wavefront 270 of light propagating through the optical waveguide 224 is not subjected to the optical confinement effect in the separation region 227A that is the region after the optical waveguide end surface 224a. According to the electrode width of the electrode 208, it gradually spreads in the horizontal direction and propagates through the separation region 227A. Thereby, since propagation loss due to light absorption can be reduced, it is possible to achieve high efficiency of light output of the semiconductor light emitting device.

  The semiconductor light emitting element 202 according to this modification can be manufactured by the same manufacturing method as that of Modification 1 of the second embodiment.

(Third embodiment)
Next, the configuration of the semiconductor light emitting device 300 according to the third embodiment of the present invention will be described with reference to FIGS. 15A and 15B. FIG. 15A is a top view of the semiconductor light emitting device according to the third embodiment of the present invention, and FIG. 15B is a cross-sectional view of the semiconductor light emitting device taken along line BB ′ of FIG. 15A. In FIGS. 15A and 15B, the same components as those shown in FIGS. 1 and 2A to 2C are denoted by the same reference numerals, and the description thereof is omitted. In this embodiment, parts different from the first embodiment are described. The explanation will be focused on.

  As shown in FIGS. 15A and 15B, in the semiconductor light emitting device 300 according to the third embodiment of the present invention, the center lines of the optical waveguide 324 and the p-side contact electrode 308 are connected perpendicularly to the rear end face 140b. The optical waveguide 324 and the p-side contact electrode 308 are bent so as to have a curved surface in the middle.

  In the present embodiment, as in the first and second embodiments, the optical waveguide 324 is formed by the recessed regions 325a and 325b in which the recessed portions 325 (not shown) are formed and the pedestal regions 326a and 326b. The opening of the block layer 309 is formed in a curved shape according to the shape of the p-side contact electrode 308.

  In the present embodiment, recessed regions 325a and 325b are also formed near the front end surface 140a. The recessed regions 325a and 325b in the vicinity of the front end surface 140a are remaining regions that remain as the remaining portions of the recessed regions 325a and 325b extending from the adjacent device regions during element isolation.

  In the present embodiment, no step groove is formed on the front end surface 140a, and the light emitting end surface 130a and the front end surface 140a coincide.

  Hereinafter, the detailed configuration of the vicinity of the front end surface 140a of the semiconductor light emitting device 300 according to the present embodiment will be described with reference to FIG. FIG. 16 is a partially enlarged view of the vicinity of the front end face of the semiconductor light emitting device according to the third embodiment of the present invention.

  As shown in FIG. 16, in the present embodiment, as described above, the optical waveguide 324 is bent in the middle, so that the optical waveguide end surface 324a is inclined with respect to the light emitting end surface 130a (front end surface 140a).

  In the present embodiment, the p-side contact electrode 308 extends to the isolation region 327A as in the second embodiment, and the contact electrode end surface 308a of the p-side contact electrode 308 is the optical waveguide end surface 324a of the optical waveguide 324. And the light emitting end face 130a. As a result, it is possible to separate the light reflected at the light emitting end face 130a and to prevent the light from being absorbed outside the optical waveguide 324.

  Next, a method for manufacturing the semiconductor light emitting device 300 according to this embodiment will be described with reference to FIGS. FIG. 17 is a view for explaining the method for manufacturing the semiconductor light emitting element according to the third embodiment of the present invention. Note that the manufacturing method of the semiconductor light emitting device 300 according to the present embodiment is the same as the manufacturing method according to the first embodiment shown in FIGS. Note that, in FIG. 17, a wafer 390 in which three semiconductor light emitting elements 300 are arranged in the horizontal direction and two in the vertical direction is shown for ease of explanation. In the present embodiment, the semiconductor multilayer structure on the substrate 101 is the same as the semiconductor multilayer structure of the semiconductor light emitting device 100 according to the first embodiment.

A hard mask material (not shown) such as SiO ₂ is formed on the surface of the wafer 390 on the substrate, and the hard mask corresponding to the two recesses 325 is formed by photolithography using a resist and dry etching using a fluorine-based gas. Form a pattern.

Subsequently, for example, two recesses 325 are formed by dry etching using a chlorine-based gas. Subsequently, after removing the hard mask remaining at the time of etching using, for example, hydrofluoric acid, an insulating film corresponding to the block layer 309 such as SiO ₂ is formed on the entire surface of the wafer 390.

  Subsequently, a resist pattern corresponding to the p-side contact electrode 308 is formed by photolithography, and a portion of the insulating film corresponding to the p-side contact electrode 308 is removed by wet etching using an etchant such as hydrofluoric acid. At this time, for example, a Pd / Pt multilayer metal film is subsequently formed, and the p-side contact electrode 308 is formed by lift-off. Subsequently, a multilayer metal film such as Ti / Pt / Au is formed on the p-side contact electrode 308 and the block layer 309 and patterned by lift-off or etching to form the wiring electrode 110. Thereby, as shown in FIG. 17, a wafer 390 is manufactured.

Subsequently, the wafer 390 is separated along the first dividing line 361 by opening the wall. Subsequently, a high-reflectance layer 150 is formed by forming a dielectric multilayer film made of, for example, SiO ₂ / ZrO _{2 on} the rear end face 140b of the element by sputtering. Subsequently, the semiconductor light emitting element 300 can be manufactured by dividing along the second dividing line 362 by laser dicing or the like.

  As described above, also in the semiconductor light emitting device 300 according to the third embodiment of the present invention, the laser oscillation in the Fabry-Perot mode can be suppressed, so that the light emission efficiency can be improved.

  In the present embodiment, the division on the first division line 361 is performed by cleavage. Thereby, the front end surface 140a can be made into an end surface that is almost completely free of irregularities. In this case, the element isolation region functions as a functional unit that further reduces the reflectance of the end face. For this reason, a sufficiently low reflectivity can be realized even if the inclination angle (end face angle) with respect to the front end face 140a (light emitting end face 130a) is made smaller than before, so that the guide by the bent portion of the optical waveguide 324 can be realized. A semiconductor light-emitting element with less wave loss can be manufactured. Further, when the end face angle is set to the conventional level, the reflectivity can be lowered to the limit, and the laser oscillation in the Fabry-Perot mode can be suppressed to a higher output and the SLD operation can be performed.

  In the present embodiment, the bent portion of the optical waveguide 324 is preferably configured to suppress the waveguide loss as much as possible, and it is desirable that the bent portion has a large radius of curvature. For example, in the case of a semiconductor light emitting device made of a nitride semiconductor having a wavelength of about 300 to 550 nm, the curvature radius of the bent portion of the optical waveguide is preferably 500 μm or more, and more preferably 1000 μm or more.

(Fourth embodiment)
Next, the structure of the semiconductor light emitting device 400 according to the fourth embodiment of the present invention will be described with reference to FIGS. 18, 19A and 19B. 18 is a top view of a semiconductor light emitting device 400 according to the fourth embodiment of the present invention. FIG. 19A is a cross-sectional view of the semiconductor light emitting device taken along line AA ′ of FIG. 18, and FIG. FIG. 19 is a cross-sectional view of the semiconductor light emitting element taken along line BB ′ in FIG. 18. In FIG. 18, FIG. 19A and FIG. 19B, the same constituent elements as those shown in FIG. 1 and FIG. 2A to FIG. It demonstrates centering on a different part.

  As shown in FIG. 18, in the semiconductor light emitting device 400 according to the fourth embodiment of the present invention, concave portions (bottom portions) 425 are formed on both sides of the optical waveguide 424, and there is a pedestal portion as shown in FIG. do not do. Further, etching grooves 432 etched to the substrate 101 are formed on both outer sides of the recess 425. The regions where the recesses 425 are formed are the recess regions 425a and 425b, and the region between the recess region 425a and the recess region 425b where the optical waveguide 424 is formed is the optical waveguide region 424A. Further, regions where the etching groove 432 is formed are referred to as etching groove regions 432a and 432b.

  Similarly to the first embodiment, a step groove 430 is formed by etching in the vicinity of the front end surface 140a, and the side wall of the step groove 430 is a light emitting end surface 430a. The normal line of the light emitting end face 430a is inclined at a constant angle with respect to the extension axis (stripe direction axis) of the optical waveguide 424.

  In this embodiment, the step groove 431 is also formed on the rear end surface 140b, and the step grooves 430 and 431 are simultaneously formed as the same groove by the same etching process. A high reflectivity layer 150 is formed on the inner side surface (the rear end surface of the optical waveguide 424) of the step groove 431 on the rear end surface 140b side.

  The n-side contact electrode 411 is formed on the substrate 101 in the etching groove region 432 b and is formed on the surface side of the semiconductor light emitting element 400.

  Hereinafter, a detailed structure near the front end face of the semiconductor light emitting device 400 according to the present embodiment will be described with reference to FIG. FIG. 20 is a partially enlarged view of the vicinity of the front end face of the semiconductor light emitting device according to the fourth embodiment of the present invention.

  As shown in FIG. 20, the light emitting portion of the semiconductor light emitting device 400 according to the present embodiment is a ridge structure laser without a pedestal, and has the same effect as the separation region 227A in the second embodiment. It has a simple structure. That is, in the separation region 427A, the width of the optical waveguide 424 is gradually enlarged, and the effective optical waveguide end face 424a and the light emitting end face 430a are separated. The first isolation region 427A1 is a region formed by extending the p-side contact electrode 408, and the second isolation region 427A2 is a region where the p-side contact electrode 408 is not formed. In the separation region 427A, the width of the optical waveguide 424 expands more rapidly than the light spread at the time of propagation, so that the separation region 427A can be regarded as effectively having no light confinement. In addition, the change in the waveguide width in the separation region 427A is sufficient if the angle is several degrees or more.

  As described above, according to the semiconductor light emitting device 400 according to the fourth embodiment of the present invention, even in a ridge structure laser without a pedestal, it is possible to effectively realize a state without light confinement. As in the embodiment, the light emission efficiency and the light output can be improved.

  Next, a method for manufacturing the semiconductor light emitting device 400 according to the fourth embodiment of the present invention will be described with reference to FIGS. 21, 19A and 19B with reference to FIG. FIG. 21 is a schematic view for explaining the method for manufacturing the semiconductor light emitting device 400 according to the fourth embodiment of the present invention. In FIG. 21, a wafer 490 is shown in which three semiconductor light emitting elements 400 are arranged in the horizontal direction and two in the vertical direction in order to simplify the description.

  First, a semiconductor multilayer film is formed on a substrate made of, for example, an insulating sapphire substrate, and a wafer 490 is manufactured. The semiconductor laminated film is the same as that of the semiconductor light emitting device 100.

Subsequently, a hard mask (not shown) such as SiO ₂ is formed on the surface of the semiconductor multilayer film on the substrate, and the recess region (first etching portion) is formed by photolithography using a resist and dry etching using a fluorine-based gas. ) A pattern corresponding to the concave portion 425 of 425a and 425b is formed. Thereafter, the first etching portion is etched by dry etching using a chlorine-based gas to form a recess 425.

Subsequently, the hard mask remaining at the time of etching is removed by, for example, hydrofluoric acid. Again, a hard mask (not shown) such as SiO ₂ is formed on the substrate, and the step grooves 430 and 431 and the etching groove 432 (second etching portion) are formed by photolithography using a resist and dry etching using a fluorine-based gas. ) Are formed. Thereafter, step grooves 430 and 431 and an etching groove 432 are formed by dry etching using a chlorine-based gas.

Subsequently, after the hard mask remaining at the time of etching is removed using, for example, hydrofluoric acid, an insulating film corresponding to the block layer 109 such as SiO ₂ is formed on the entire surface of the wafer 490. Subsequently, a resist pattern corresponding to the p-side contact electrode 408 is formed by photolithography, and a portion of the insulating film corresponding to the p-side contact electrode 408 is removed by wet etching using a hydrofluoric acid etchant.

  Subsequently, for example, a Pd / Pt multilayer metal film is formed and patterned by lift-off or metal etching to form a p-side contact electrode 408. Subsequently, for example, a multilayer metal film such as Ti / Al / Ni / Au is formed and patterned by lift-off or metal etching to form the n-side contact electrode 411. Subsequently, a multilayer metal film such as Ti / Pt / Au is formed on the p-side contact electrode 408 and the block layer 109, and the wiring electrode 110 is formed by patterning by lift-off or etching.

Subsequently, the high reflectivity layer 150 is formed on the inner wall portion of the step groove 431 by forming, for example, a SiO ₂ / ZrO ₂ dielectric multilayer film from an oblique direction. Thereby, the wafer 490 shown in FIG. 21 is produced.

  Subsequently, as shown in FIG. 21, the wafer 490 is divided along the first dividing line 461 by, for example, laser dicing or wall opening. The semiconductor light emitting device 400 is manufactured by continuously dividing along the second dividing line 462 by laser dicing or the like.

  In the present embodiment, since the step groove 431 is formed also in the rear end surface 140b, the division in the first division line 461 can be performed by dicing such as laser dicing. Thereby, since it is not necessary to perform cleavage, mass productivity is improved.

  In this embodiment, since the n-side contact electrode 111 is formed on the surface side of the semiconductor light emitting device 400, an insulating sapphire substrate can be used as the substrate 101, and a highly efficient light emitting device can be used. It can be manufactured at a low cost.

(Modification)
Next, a semiconductor light emitting element 401 according to a modification of the fourth embodiment of the present invention will be described with reference to FIG. FIG. 22 is a partially enlarged view of the vicinity of the light emitting end face of the semiconductor light emitting device according to the modification of the fourth embodiment of the present invention. Note that in this modification, the description of the same components as those in the above-described fourth embodiment will be omitted, and different portions will be mainly described.

  As shown in FIG. 22, in the present modification, the width of the optical waveguide 424 is discontinuously enlarged at the boundary between the optical waveguide region 424A and the separation region 427A.

  Thus, by effectively increasing the width of the optical waveguide 424, a state without optical confinement can be realized effectively. Therefore, the same effect as that of the semiconductor light emitting device 400 according to the fourth embodiment can be obtained.

(Fifth embodiment)
Next, the structure of the semiconductor light emitting device 500 according to the fifth embodiment of the present invention will be described with reference to FIGS. 23A to 23C. FIG. 23A is a partially enlarged view of the vicinity of the light emitting end face of the semiconductor light emitting device according to the fifth embodiment of the present invention, and FIG. 23B is a cross-sectional view of the semiconductor light emitting device taken along line AA ′ of FIG. FIG. 23C is a cross-sectional view of the semiconductor light-emitting element taken along line BB ′ in FIG. 23A. Since the structure of the semiconductor light emitting device 500 in this embodiment is basically the same as the structure of the semiconductor light emitting device 100 in the first embodiment, FIGS. 23A to 23C show FIGS. Constituent elements that are the same as the constituent elements shown are denoted by the same reference numerals, description thereof is omitted, and different portions will be mainly described.

  As shown in FIGS. 23A to 23C, in the semiconductor light emitting device 500 according to this embodiment, a substrate step portion 517 is formed on the substrate 101. The substrate step portion 517 is a recess formed in the upper part of the substrate 101. As described above, when the semiconductor laminated film is formed on the substrate 101 provided with the substrate step portion 517, the active layer shortening portion 504 is formed as a portion where the band gap is widened in the active layer 104 near the substrate step portion 517. It is formed.

  That is, when a semiconductor laminated film including the active layer 104 is formed on the substrate 101 on which the substrate step portion 517 is formed, indium (In) is formed on the substrate 101 in the vicinity of the substrate step portion 517 and other than the vicinity of the substrate step portion 517. Therefore, the active layer shortening region 504A is naturally formed in the semiconductor laminated film at the peripheral portion of the stepped portion 517 of the substrate. Note that a region of the semiconductor layer stack in which the active layer wavelength shortening portion 504 is formed in the active layer 104 is referred to as an active layer wavelength shortening region 504A.

  Then, the optical waveguide 524, the p-side contact electrode 108, and the step groove (etching end face groove) 530 are formed so that the isolation region 527A is formed in the active layer short wavelength region 504A.

  According to the semiconductor light emitting device 500 according to the present embodiment, the active layer 104 in the isolation region 527A is windowed by the substrate step portion 517, so that the light absorption loss in the isolation region 527A can be eliminated.

  That is, the light emitted from the optical waveguide 524 propagates through the separation region 527A and is emitted to the outside from the light emitting end surface 530a of the step groove 530, but the light is the short wavelength of the active layer 104 of the active layer 104 in the separation region 527A. Propagating through the conversion unit 504 enables propagation without loss of light absorption.

  Therefore, since there is no decrease in the light emission efficiency, the light emission efficiency can be further improved.

  According to the semiconductor light-emitting device of the present invention, the light-emitting efficiency of the semiconductor light-emitting device can be increased. Therefore, the semiconductor light-emitting device can be widely used as a light source with a thin shape, low power consumption, and low cost. It is useful as a backlight light source for a display device or a light source for a projector.

100, 200, 201, 202, 300, 400, 401, 500, 2000 Semiconductor light emitting device 101 Substrate 102 n-type cladding layer 103 n-type light guide layer 104 active layer (light-emitting layer)
105 p-type light guide layer 106 electron barrier layer 107 p-type cladding layer 107a ridge portion 108, 208, 308, 408 p-side contact electrode 108a, 208a, 308a contact electrode end face 109, 209, 309 block layer 110 wiring electrode 111, 411 N-side contact electrode 124, 224, 324, 424, 524 Optical waveguide 124a, 224a, 324a, 424a Optical waveguide end face 124A, 224A, 424A Optical waveguide region 125, 325, 425 Recessed portion 125a, 125b, 225a, 225b, 325a, 325b 425a, 425b Recessed area 126a, 126b, 226a, 226b, 326a, 326b Pedestal area 127A, 227A, 327A, 427A, 527A Separating area 130, 430, 431, 53 Step groove 130a, 430a, 530a Light exit end face 130A Step groove region 140a Front end face 140b Rear end face 150 High reflectivity layer 161, 361, 461 First split line 162, 362, 462 Second split line 170 Propagating light 171 Reflected Light 172, 173 Scattered light 190, 390, 490 Wafer 208W1 First electrode width 208W2 Second electrode width 227A1, 427A1 First separation region 227A2, 427A2 Second separation region 270 Wavefront 325a, 325b Optical waveguide remainder 432 Etching groove 432a 432b Etching groove region 504 Active layer shortening portion 504A Active layer shortening region 517 Substrate step portion 1000 Semiconductor laser amplifier 1010, 1011 Termination cap portion 1012 Waveguide 1013 Incident end face 1014 Emission end face 1 DESCRIPTION OF SYMBOLS 15 Semiconductor region 1016 Semiconductor main body 1017, 1018 Facet 1019 Surface 2001 GaN substrate 2002 1st clad layer 2003 1st guide layer 2004 Multiple quantum well layer 2005 2nd guide layer 2006 Barrier layer 2007 2nd clad layer 2008 p side contact electrode layer 2010 Insulating layer 2011 n-side contact electrode layer 2012 oblique facet plane

Claims (11)

A semiconductor light emitting device comprising a semiconductor layer stack having a light emitting layer formed above a substrate and a light emitting end face that emits light emitted from the light emitting layer,
An optical waveguide for confining and guiding light emitted from the light emitting layer;
A region between the light guide end face and the light exit end face, which is an end face of the light guide end face side of the light guide, and transmits light from the light guide from the light guide end face to the light exit end face. And a separation region that is a region that is allowed to pass through without being substantially confined in the horizontal direction,
The optical waveguide end face is inclined with respect to the light emitting end face. Semiconductor light emitting element. The semiconductor light emitting element according to claim 1, wherein the optical waveguide and the isolation region are formed of the same semiconductor layer stack. The semiconductor light emitting element according to claim 1, wherein a distance between the end face of the optical waveguide and the end face of the light emission is 1 μm or more. Furthermore, a contact electrode formed above the optical waveguide is provided,
4. The semiconductor light emitting element according to claim 1, wherein an end of the contact electrode on the light emitting end face side extends to the end face of the optical waveguide and the light emitting end face. The part or all of the width of the contact electrode formed between the optical waveguide end face and the light emitting end face is wider than the width of the contact electrode formed above the optical waveguide. Semiconductor light emitting device. The semiconductor light emitting element according to claim 5, wherein a width of the contact electrode formed between the waveguide end face and the light emitting end face gradually increases from the optical waveguide end face toward the light emitting end face. The semiconductor light emitting element according to claim 1, wherein the light emitting end face is a cleavage plane. Furthermore, a step groove formed to cut out the semiconductor layer stack,
The semiconductor light emitting element according to claim 1, wherein the light emitting end surface is an inner surface of the step groove. The semiconductor light emitting element according to claim 8, wherein the step groove is formed by etching. The semiconductor light emitting element according to claim 1, further comprising a substrate step portion formed on the substrate in the separation region or a region near the separation region. The semiconductor light emitting element according to claim 1, wherein a part or all of the separation region is a region that transmits light from the optical waveguide without substantially absorbing it.

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