JP2018182154A - Surface emitting semiconductor light-emitting element and manufacturing method of the same - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a surface emitting semiconductor element capable of improving optical output and light-extraction efficiency in a simple constitution; and provide a manufacturing method of the surface emitting semiconductor element.SOLUTION: A surface emitting LED 10 comprises: a multilayer semiconductor laminate 15 including a p-type semiconductor layer 2, an n-type semiconductor layer 3 and an active layer 1 arranged between the p-type semiconductor layer 2 and the n-type semiconductor layer 3; a p-side electrode 11 formed on an outside surface on the p-type semiconductor layer 2 side; an n-side electrode 12 formed on an outside surface on the n-type semiconductor layer 3 side; a first reflection member which covers lateral faces of the semiconductor laminate 15; and a second reflection member which covers either one of two outside surfaces opposite to each other in a lamination direction of the semiconductor laminate 15.SELECTED DRAWING: Figure 3

Description

  The present invention relates to a surface emitting semiconductor light emitting device and a method of manufacturing the same.

  2. Description of the Related Art A surface emitting light emitting diode (LED) is conventionally known as a surface emitting semiconductor light emitting element for emitting light in a direction substantially perpendicular to a layer grown epitaxially. In such a surface-emitting LED, it is desired to improve the light extraction efficiency in the direction in which light is desired to be extracted (light extraction direction).

As a method for improving the light extraction efficiency described above, for example, in Patent Document 1, a reflective cup is installed in the vicinity of the LED at the time of mounting, and light emitted from the side of the LED is reflected by the reflective cup A method of focusing in a direction is disclosed. Further, in Patent Document 2, in the surface emitting type LED, light is emitted between the semiconductor substrate and the light emitting portion, and light emitted from the active layer contained in the light emitting portion is reflected to the opposite side to the semiconductor substrate which is the light extraction direction. The point of providing a part is disclosed.
Further, Patent Document 3 discloses that a light extraction efficiency is improved by forming a concavo-convex pattern such as a nano structure such as a photonic crystal or a moth eye structure on a light extraction surface. Further, Patent Document 4 discloses a micro-cavity LED in which the intensity of emitted light in the light emission direction is increased by a fine resonator structure.

Unexamined-Japanese-Patent No. 11-8415 gazette JP, 2011-176001, A JP, 2013-16537, A Unexamined-Japanese-Patent No. 9-283862

  In the technology described in Patent Document 1, the mounting becomes complicated because it is necessary to separately provide a mirror on the outside of the LED. Further, in the technology described in Patent Document 2, the light emitting portion emitted from the side of the active layer is arranged because the reflecting portion is disposed only on the surface opposite to the light extraction direction with respect to the active layer. As long as light is not applied to the technology described in Patent Document 1 or the like, it is a loss as it is, and the light output and the light extraction efficiency are reduced accordingly.

Furthermore, in the technique described in Patent Document 3, since it is necessary to separately form a photonic crystal structure or a moth-eye structure, the manufacturing process is increased and the process becomes complicated accordingly. In addition, there is a concern that only light in a specific wavelength range can be extracted (the wavelength width of the light that can be extracted is narrower than the emission wavelength width of the surface-emitting type LED). Further, in the microcavity LED described in Patent Document 4, in order to resonate the spontaneous emission light, when the wavelength of the emitted light is λ and the refractive index of the active layer is n _a , the thickness of the active layer is λ / ( must be 2 × n _a) extent, freedom of design is limited. Furthermore, the element structure is complicated such as forming a dielectric multilayer reflective film for forming a cavity.

  Then, this invention makes it a subject to provide the surface emitting type semiconductor light-emitting device which can improve light output and light extraction efficiency by simple structure, and its manufacturing method.

In order to solve the above problems, one aspect of the surface emitting semiconductor light emitting device according to the present invention is a p-type semiconductor layer, an n-type semiconductor layer, and a space between the p-type semiconductor layer and the n-type semiconductor layer. An active layer disposed, a p-side electrode formed on an outer surface of the p-type semiconductor layer side of the semiconductor stack, and an n-type semiconductor layer side of the semiconductor stack An n-side electrode formed on the outer surface of the semiconductor stack, a first reflecting member that covers the side surface of the semiconductor stack, and a second one that covers any one of two outer surfaces facing in the stacking direction of the semiconductor stack. And a reflective member.
Thus, by covering the side of the active layer of the semiconductor laminate with the first reflecting member, the emitted light emitted from the side of the active layer is reflected by the first reflecting member, and is used again as the emitted light. can do. In addition, one of the emitted light emitted from the active layer in the stacking direction of the semiconductor laminate can be reflected by the second reflecting member and can be propagated in the direction in which the second reflecting member is not disposed. . Therefore, the light output can be increased and the efficiency can be improved with a simple configuration.

Further, in the above-described surface-emitting type semiconductor light-emitting device, the second reflection member may be provided on the surface of the two outer surfaces opposite to the light extraction direction. As described above, the first reflective member and the second reflective member may cover the surface of the semiconductor laminate other than the light extraction direction. This makes it possible to increase the light output in the direction in which light is desired to be reliably extracted.
Furthermore, in the above-described surface-emitting type semiconductor light emitting device, the light extraction direction may be a direction in the stacking direction toward the side on which the n-type semiconductor layer is disposed with respect to the active layer. In this case, it is possible to obtain an n-side emission type surface-emitting semiconductor light-emitting device that emits emission light from the side on which the n-side electrode is formed.

In the above-described surface-emitting type semiconductor light-emitting device, the first reflecting member and the second reflecting member may be continuously and integrally formed on the semiconductor laminate. In this case, the side surface and the one outer surface of the semiconductor laminate can be covered by the reflective member without leakage. In addition, since the first reflecting member and the second reflecting member can be simultaneously formed in one step, the manufacturing process is simplified.
Furthermore, in the above-described surface-emitting type semiconductor light emitting device, the first reflecting member and the second reflecting member may be made of a metal material. Thereby, light emitted from the active layer can be appropriately reflected.

In the above-described surface-emitting type semiconductor light-emitting device, the second reflecting member may also serve as either one of the p-side electrode and the n-side electrode. In this case, there is no need to provide a second reflecting member separately from the p-side electrode, and the number of parts can be reduced. Therefore, the element can be miniaturized and the cost can be reduced.
Furthermore, in the above-described surface-emitting type semiconductor light emitting device, the p-side electrode and the n-side electrode may be formed at positions which do not overlap with each other as viewed in the stacking direction of the semiconductor laminate. In this case, the electrodes can be disposed so as not to shield the emitted light, and the decrease in light output and light extraction efficiency can be appropriately suppressed.

In the above-described surface-emitting type semiconductor light-emitting device, the shape of the semiconductor laminate covered by the first reflecting member may be a cylindrical shape in which the stacking direction is an axial direction. The cylindrical shape is a three-dimensional shape in which the cross-sectional shape orthogonal to the light extraction direction of the surface-emitting type semiconductor light emitting device is circular or substantially circular (including elliptical), and includes, for example, a truncated cone.
Thus, by making the shape of the semiconductor laminate into a cylindrical shape, it is possible to obtain a uniform light emission pattern and intensity. Further, the emitted light propagated to the side surface of the active layer of the semiconductor laminate can be reflected in the normal direction of the side surface by the first reflecting member. Therefore, the reflection characteristic due to the difference in the propagation direction to the side can be made uniform, and photon recycling can be efficiently caused. That is, the light emitted from the side of the active layer can be easily utilized as the emission light emitted again from the active layer.

Furthermore, in the above-described surface-emitting type semiconductor light-emitting device, the surface-emitting type semiconductor light-emitting device may further include an insulating layer disposed between the side surface of the semiconductor laminate and the first reflecting member. In this case, even when the first reflection member is made of a conductive material, the first reflection member prevents the p-type semiconductor layer and the n-type semiconductor layer from being electrically connected. can do.
In the above-described surface-emitting type semiconductor light emitting device, the insulating layer is further formed on the periphery of the outer surface on the p-type semiconductor layer side, and the p-side electrode is the outer surface on the p-type semiconductor layer side The insulating layer may be connected to a region where the insulating layer is not formed. As a result, the holes injected from the p-side electrode reach the interface between the semiconductor layer and the insulating layer 5 by diffusion in the horizontal direction, and they become non-emission current as carriers flowing through the interface and suppress the reduction of internal quantum efficiency. Can.

Furthermore, in the above-described surface-emitting type semiconductor light-emitting device, the semiconductor laminate may further include an InP substrate formed on the main surface. In this case, a surface emitting semiconductor light emitting device can be obtained which emits light having a wavelength of 1000 nm to 1650 nm, and can be used for a wide variety of uses.
In the above-mentioned surface emitting semiconductor light emitting device, the surface emitting semiconductor light emitting device may be a surface emitting light emitting diode. That is, it is possible to realize a surface-emitting light emitting diode with high output and light efficiency with a simple configuration.

Furthermore, one aspect of the method for manufacturing a surface emitting semiconductor light emitting device according to the present invention is arranged between a p-type semiconductor layer, an n-type semiconductor layer, the p-type semiconductor layer, and the n-type semiconductor layer. And a step of covering the side surface of the multilayer semiconductor laminate including the active layer with a first reflection member, and covering any one of two outer surfaces opposed in the lamination direction of the semiconductor laminate with a second reflection member. And the process.
As a result, the light emitted from the side of the active layer is reflected by the first reflecting member, and one of the light emitted from the active layer in the stacking direction of the semiconductor laminate is reflected in the second direction. A surface emitting semiconductor light emitting element that can be reflected by a member can be obtained. Therefore, the light output can be increased and the efficiency can be improved with a simple configuration.

  According to the present invention, in the surface-emitting type semiconductor device, the light output and the light extraction efficiency can be improved with a simple configuration.

It is a perspective view which shows the structural example of the surface emitting type LED in 1st embodiment. It is a perspective view which shows the structural example of the surface emitting type LED in 1st embodiment. It is a schematic block diagram around a mesa of a surface emitting type LED of a first embodiment. It is a figure explaining the manufacturing process of the surface-emitting type LED of 1st embodiment. It is a figure explaining the manufacturing process of the surface-emitting type LED of 1st embodiment. It is a figure explaining the manufacturing process of the surface-emitting type LED of 1st embodiment. It is a figure explaining the manufacturing process of the surface-emitting type LED of 1st embodiment. It is a figure explaining the manufacturing process of the surface-emitting type LED of 1st embodiment. It is a figure explaining the manufacturing process of the surface-emitting type LED of 1st embodiment. It is a figure explaining the manufacturing process of the surface-emitting type LED of 1st embodiment. It is a figure explaining the manufacturing process of the surface-emitting type LED of 1st embodiment. It is a figure explaining the manufacturing process of the surface-emitting type LED of 1st embodiment. It is an example of mounting of the surface emitting type LED of 1st embodiment. It is a perspective view which shows the structural example of the surface emitting type LED in 2nd embodiment. It is an example of the shape of the metal mirror electrode of 2nd embodiment. It is the schematic of the cross section of the surface emitting type LED of 2nd embodiment.

Hereinafter, embodiments of the present invention will be described based on the drawings.
The embodiment described below is an example as a realization means of the present invention, and should be appropriately corrected or changed according to the configuration of the apparatus to which the present invention is applied and various conditions. It is not limited to the embodiment. In the drawings described below, the same or functionally similar components are denoted by the same reference numerals, and the repetitive description thereof will be omitted. Further, each drawing is illustrated for clarity when referred to in conjunction with the following description, and is not necessarily drawn to scale.

(First embodiment)
FIG. 1 and FIG. 2 are diagrams showing a configuration example of the surface emitting semiconductor light emitting device in the present embodiment. In the present embodiment, the case where the surface emitting semiconductor light emitting element is a surface emitting light emitting diode (LED) will be described. Here, FIG. 1 is a perspective view (bird's eye view) showing the surface of the surface emitting type LED 10 opposite to the light extracting direction (light emitting direction), and FIG. 2 is a surface of the surface emitting type LED 10 as the light extracting direction. It is a perspective view (bird's eye view) shown.
In the present embodiment, the surface-emitting LED 10 will be described as emitting emitted light L having a wavelength of 1000 nm to 1650 nm. The surface-emitting LED 10 includes a p-side electrode 11 formed on the outer surface (p-side surface) opposite to the light extraction direction and an n-side electrode formed on the outer surface (n-side surface) on the light extraction direction 12 and a light emitting unit 13 for emitting light. That is, the surface-emitting LED 10 in the present embodiment is an n-side emission surface-emitting LED.

The light emission light emitted by the light emitting unit 13 is emitted as the emission light L from the emission region L1 of the n-side surface. Here, the position and the size of the emission area L1 correspond to the position and the size of the light emitting unit 13.
Further, the n-side electrode 12 is disposed at a position not shielding the outgoing light L on the n-side surface. Specifically, the n-side electrode 12 is disposed on the n-side surface so as to be offset from the emission region L1 corresponding to the region in which the light emitting unit 13 is disposed.

In the present embodiment, the light emitting unit 13 is configured to include a semiconductor stack (hereinafter, simply referred to as “mesa”) having a mesa structure in which a plurality of semiconductor layers are stacked. Hereinafter, a specific configuration around the mesa will be described with reference to FIG.
As shown in FIG. 3, the light emitting unit 13 includes a mesa 15 formed on the substrate 14. The mesa 15 includes an active layer 1, a p-type semiconductor layer (p-type cladding layer) 2 and an n-type semiconductor layer (n-type cladding layer) 3 arranged to sandwich the active layer 1, and a p-type semiconductor layer 2. And a contact layer 4 disposed on the
In the present embodiment, the mesa 15 has a cylindrical shape whose axial direction is the stacking direction of the semiconductor layers. Here, the cylindrical shape in the present embodiment is a three-dimensional shape in which the cross-sectional shape orthogonal to the light extraction direction of the surface-emitting type LED 10 is circular or substantially circular (including elliptical), and includes, for example, a truncated cone . In addition, the shape of the mesa 15 is not limited to a cylindrical shape, It can be set as arbitrary shapes.

The substrate 14 is, for example, an n-type InP substrate. The active layer 1 is made of, for example, undoped InGaAsP, the p-type semiconductor layer 2 is made of, for example, p-type InP, and the n-type semiconductor layer 3 is made of, for example, n-type InP. The contact layer 4 is made of, for example, p-type InGaAs.
The active layer 1 may be made of an InGaAlAs material. Furthermore, the p-type semiconductor layer 2 and the n-type semiconductor layer 3 may be made of InGaAsP, InGaAlAs, InAlAs, InGaAs, or the like.

The p-side electrode 11 is formed on the p-side surface, which is the outer surface on the p-type semiconductor layer 2 side, so as to cover the mesa 15 via the insulating layer 5. The insulating layer 5 can be made of SiO ₂ , SiN, Al ₂ O ₃ or the like. In the insulating layer 5, for example, a circular opening 5 a is provided at the top of the mesa 15, and the p-side electrode 11 is electrically connected to the contact layer 4 in the opening 5 a. Thus, the p-side electrode 11 covers the side surface of the mesa 15 and the surface of the mesa 15 opposite to the light extraction direction. Although not shown in FIG. 3, the n-side electrode 12 is formed on the outer surface on the n-type semiconductor layer 3 side (the surface of the substrate 14 opposite to the mesa 15).

The p-side electrode 11 is made of a metal, and includes at least one of Ti, Cr, Mo, W, Ni, Pt, Cu, Ag, and Au. For example, the p-side electrode 11 can be a multilayer metal film in which a Ti film, a Pt film and an Au film are sequentially laminated. In addition, the n-side electrode 12 can have the same configuration as the p-side electrode 11.
In the present embodiment, the p-side electrode 11 is a reflecting member that plays a role of a mirror that reflects light. Specifically, the p-side electrode 11 is a first reflection member that covers the side surface of the mesa 15 and a surface (p-type) of the two outer surfaces facing in the stacking direction of the mesa 15 opposite to the light extraction direction And a second reflection member covering the outer surface of the semiconductor layer 2). In the following description of the present embodiment, the p-side electrode 11 is also referred to as a metal mirror electrode 11.

  The carriers injected from the metal mirror electrode 11 and the n-side electrode 12 are recombined in the active layer 1 to become emitted light, and the direction of the p-type semiconductor layer 2 opposite to the light extraction direction (FIG. Upward direction, the direction of the n-type semiconductor layer 3 (lower direction in FIG. 3) which is the light extraction direction, and the lateral direction (horizontal direction in FIG. 3) of the active layer 1 which is the direction orthogonal to the light extraction direction. And to the Among these, the light propagated to the p-type semiconductor layer 2 side is reflected to the n-type semiconductor layer 3 side by the metal mirror electrode (first reflection member) 11 on the contact layer 4. Further, the light propagated in the lateral direction of the active layer 1 is reflected by the metal mirror electrode (second reflective member) 11 of the side of the active layer 1 and returned to the active layer 1.

  As described above, the active layer 1 has a cylindrical shape. Therefore, the light propagated to the side of the active layer 1 is substantially vertically reflected by the metal mirror electrode 11 formed on the side without a difference in reflection characteristics due to a difference in propagation direction. And while repeating it, it is efficiently absorbed in the active layer 1 (photon recycling), becomes a carrier, and emits light again as the direction of the p-type semiconductor layer 2 and the direction of the n-type semiconductor layer 3 and the side of the active layer 1 It will propagate in the direction. That is, the light propagated to the side of the active layer 1 can be efficiently reused as emission light.

  As described above, the surface-emitting type LED 10 in the present embodiment includes the metal mirror electrode 11 that covers the surface of the active layer 1 of the mesa 15 other than the light extraction direction. Therefore, among the light emitted from the active layer 1, the light propagated in the direction other than the light extraction direction can be emitted as the emitted light L in combination with the light propagated in the light extraction direction. Therefore, compared with the case where the metal mirror electrode 11 is not provided, the outgoing light L with high output and high efficiency can be obtained.

Next, a method of manufacturing the surface-emitting type LED 10 in the present embodiment will be described.
When manufacturing the surface emitting LED 10, first, as shown in FIG. 4, the n-type semiconductor layer 3 is formed on the substrate 14 using MOCVD (Metal Organic Chemical Vapor Deposition) or LPE (Liquid Phase Epitaxy) method, etc. The active layer 1 is formed on the semiconductor layer 3, the p-type semiconductor layer 2 is formed on the active layer 1, and the contact layer 4 is formed on the p-type semiconductor layer 2. In this way, a wafer on which the semiconductor multilayer film is epitaxially grown is prepared.

Next, as shown in FIG. 5, an SiO ₂ film 6 is formed on the contact layer 4, and then, as shown in FIG. 6, a part of the SiO ₂ film 6 is removed by photolithography as a removal region 6a. Do. At this time, the SiO ₂ film 6 corresponding to the position of the groove 7 (FIG. 7) for electrically separating the light emitting portion 13 including the mesa 15 described above and the element portion other than the light emitting portion 13 is removed. When the mesa 15 has a cylindrical shape as in the present embodiment, the removal region 6a can be formed in an annular shape. For example, the removal region 6a can be outside the region of 100 μm in diameter centered on the central axis of the mesa 15 and in the region of 120 μm in diameter centered on the central axis of the mesa 15.

Next, as shown in FIG. 7, the semiconductor multilayer film is etched by the etching step until the n-type semiconductor layer 3 is achieved using the SiO ₂ film 6 as a mask to form a groove 7. Then, as shown in FIG. 8, the SiO ₂ film 6 formed on the contact layer 4 is removed to form a columnar mesa 15. Thus, a cylindrical mesa 15 with a diameter of 100 μm is formed.
Next, as shown in FIG. 9, the insulating layer 5 is formed on the outer surface opposite to the substrate 14, and a portion of the insulating layer 5 is removed by photolithography as shown in FIG. 10 to form the opening 5a. To expose the contact layer 4 on the mesa 15 from the opening 5a. Here, the diameter of the opening 5a can be about 90 μm. Thus, the diameter of the opening 5 a is set smaller than the diameter of the mesa 15. That is, the insulating layer 5 is left on the peripheral portion of the upper surface of the contact layer 4.

Then, as shown in FIG. 11, the metal mirror electrode 11 is integrally formed so as to cover the upper side of the contact layer 4 and to be in electrical contact with the contact layer 4 and to cover the side of the active layer 1. Here, the metal mirror electrode 11 can have, for example, a multilayer structure including Ti, Pt, and Au in this order from the contact layer 4 side. In the present embodiment, since the mesa 15 has a cylindrical shape, good coverage can be obtained for both the insulating layer 5 and the metal mirror electrode 11. Thus, the light emitting unit 13 is formed.
Finally, as shown in FIG. 12, the substrate 14 is polished so that the thickness of the element becomes a desired thickness (for example, about 150 μm), and the n-side electrode 12 is formed on the polished surface. Type LED 10 is manufactured. At this time, the n-side electrode 12 is formed at a position other than the propagation region (a region transmitting in one pass) when the light emitted from the light emitting portion 13 (active layer 1) passes without being reflected. That is, as shown in FIG. 2, the n-side electrode 12 is disposed on the n-side surface in an offset manner with respect to the region (emission region L1) facing the region where the p-side electrode 11 on the p-side surface is disposed. .

FIG. 13 is a view showing a mounting example of the surface-emitting type LED 10 in the present embodiment. As shown in FIG. 13, the surface-emitting type LED 10 is mounted on the heat sink 20 by solder or the like so that the metal mirror electrode 11 is in electrical contact. On the other hand, one end of the wire 21 is bonded to the n-side electrode 12. By applying a bias in the forward direction in such a state, light emitted from the light emitting unit 13 (active layer 1) is emitted from the n-side surface to the outside.
Further, by arranging and mounting the light emitting unit 13 on the side close to the heat sink 20, so-called junction down mounting, the heat generated in the light emitting unit 13 at the time of light emission is efficiently dissipated as shown by the arrows in FIG. You can escape to.

  An LED emitting light with a wavelength of 1000 nm to 1650 nm can be manufactured by epitaxially growing a semiconductor material such as InP, InGaAs, InGaAsP, InGaAlAs, InAlAs, etc. on an InP substrate. Since the refractive index of the above semiconductor material is about 3.1 to 3.4 in the wavelength range of 1000 nm to 1650 nm, the total reflection angle of the emitted light to air is very narrow at most 20 ° at most, The emitted light is totally reflected at the interface between the semiconductor and the air, and basically it is difficult to extract it to the outside.

  In addition, the emitted light propagates isotropically not only in the light extraction direction but basically. Therefore, in the surface-emitting type LED, the light emission is isotropically emitted to the outside unless the reflection member for reflecting the light propagated in the direction other than the light extraction direction as in the present embodiment is not provided. That is, in the surface emitting type LED, among emitted light that can be extracted to the outside, in the light extraction direction, the amount of light propagated in a direction different from the target direction (a direction opposite to the light extraction direction, side direction, etc.) The light output and the light extraction efficiency become low. Therefore, to achieve high output and high efficiency, improvement of external quantum efficiency is an issue. Here, external quantum efficiency = (internal quantum efficiency) × (light extraction efficiency).

  The surface-emitting type LED 10 in the present embodiment is an n-side emission type surface-emitting type LED, and as described above, the first reflection member that covers the side surface of the semiconductor laminate 15 and the light extraction direction of the semiconductor laminate 15 And a second reflective member covering an outer surface on the p-type semiconductor layer 2 side which is a surface on the opposite side of Further, in the present embodiment, the second reflection member also serves as the p-side electrode 11, and the first reflection member and the second reflection member are continuously and integrally formed on the semiconductor laminate 15. Thus, the metal mirror electrode 11 is configured.

As described above, by arranging the metal mirror electrode 11 on the side of the active layer 1 of the semiconductor laminated body 15, the emitted light emitted from the side of the active layer 1 is reflected by the metal mirror electrode 11. Can be returned to Further, by arranging the metal mirror electrode 11 on the outer surface of the semiconductor laminate 15 on the p-type semiconductor layer 2 side, the metal mirror electrode 11 reflects the emitted light emitted from the active layer 1 to the p-type semiconductor layer 2 side. Can be propagated to the n-type semiconductor layer 3 side. Therefore, the light output in the light extraction direction can be easily increased and the efficiency can be increased without the need for additional processing or members, and without losing the freedom of design.
Furthermore, since the first reflecting member and the second reflecting member are integrally formed, the manufacturing process is simplified. Further, since the second reflection member also serves as the p-side electrode 11, there is no need to provide a second reflection member separately from the p-side electrode 11, and the elements of the element can be reduced. Cost can be reduced. However, the configuration is not limited to the configuration in which the second reflecting member doubles as the p-side electrode 11, and a second reflecting member may be provided separately from the p-side electrode 11.

  In the surface emitting LED, the active layer is a light emitting layer in which a current injection region emits light, and a current non-injection region in the periphery thereof is an absorption layer which absorbs light. So, in this embodiment, the light emission part 13 is made into a mesa structure, and the loss resulting from the light absorption by said absorption layer is suppressed. Furthermore, in the present embodiment, since the active layer 1 of the mesa 15 has a cylindrical shape, uniform light emission pattern and intensity can be obtained. Further, since the active layer 1 of the mesa 15 is formed in a cylindrical shape and the side surface thereof is covered with the first reflecting member, the emitted light propagated to the side of the active layer 1 can be reflected in the normal direction of the side surface. . Therefore, the reflection characteristic due to the difference in the propagation direction to the side can be made uniform, and photon recycling can be efficiently caused. That is, the light emitted from the side of the active layer 1 can be easily utilized as the emission light emitted again from the active layer 1.

  Furthermore, in the present embodiment, the insulating layer 5 is disposed between the side surface of the semiconductor laminate 15 and the metal mirror electrode 11 as the first reflecting member, and the outside of the semiconductor laminate 15 on the p-type semiconductor layer 2 side. The insulating layer 5 is also disposed on the peripheral portion of the surface. Then, the metal mirror electrode 11 is connected to a region where the insulating layer 5 is not formed on the outer surface on the side of the p-type semiconductor layer 2 described above. For example, in the present embodiment, the diameter of the opening 5a of the insulating layer 5 is about 10 μm smaller than the diameter of the mesa 15, and the area of the opening 51a is about 80% of the cross-sectional area of the mesa 15. As a result, among the injected carriers, in particular, holes are diffused in the horizontal direction to reach the interface between the semiconductor layer and the insulating layer 5, and the carriers flowing through the interface become non-emission current as carriers flowing through the interface, thereby suppressing reduction in internal quantum efficiency. can do.

Further, if the diameter of the opening 5a is extremely reduced, for example, by making the diameter of the opening 5a about half the diameter of the mesa 15, the injected holes do not extend over the entire active layer 1 of the mesa 15. In this case, the region where the carrier has not spread becomes the current non-injection region, which becomes the absorption region of the emitted light, and the light extraction efficiency is lowered. In the present embodiment, the decrease in the light extraction efficiency can be suppressed by not making the diameter of the opening 5 a extremely smaller than the diameter of the mesa 15 (having an area ratio of about 80%).
As described above, since the decrease in internal quantum efficiency and the decrease in light extraction efficiency are suppressed, the external quantum efficiency can be improved, and high output and high efficiency can be appropriately realized.

Furthermore, in the present embodiment, the n-side electrode 12 is disposed offset to the emission region L1 on the n-side surface, and the p-side electrode 11 and the n-side electrode 12 are arranged from the stacking direction of the semiconductor stack 15. We look at each other so as not to overlap each other. As a result, in the n-side emission type surface-emitting type LED 10, the n-side electrode 12 can not block the emitted light L, and a decrease in light output can be prevented.
The light extraction efficiency can be further improved by forming an antireflective film or the like on the propagation region in the light extraction direction of the emitted light and the periphery thereof. In this case, the reflectance of the antireflective film needs to be lower than that in the case where the antireflective film is not formed. For example, in the case of an LED emitting light of 1300 nm, the reflectance between the InP substrate (n ₁ 3.2 3.2) and air (n ₀ = 1) is [(n ₁ −n ₀ ) / (n ₁ + n) ₀ )] ² ≒ 30%, so the antireflective film is formed to be less than 30%.

  As described above, according to the present embodiment, it is possible to realize a high power and high efficiency surface emission type LED 10 with a simple configuration.

Second Embodiment
Next, a second embodiment of the present invention will be described.
In the first embodiment described above, the n-side emission type surface emitting LED 10 that emits the emission light L from the n-side electrode 12 side has been described. In the second embodiment, a p-side emission type surface-emitting LED 10A that emits emission light L from the p-side electrode 11 will be described.
FIG. 14 is a perspective view (bird's eye view) showing the surface of the surface-emitting type LED 10A in the present embodiment on the light extraction direction side. The surface-emitting LED 10A includes a p-side electrode 11A on the p-side surface and an n-side electrode 12A on the n-side surface. Also, one end of a carrier injection wire 21 is bonded to the p-side electrode 11A.

  The p-side electrode 11A covers the side surface of the mesa 15 and the surface of the mesa 15 on the p-type semiconductor layer 2 side, similarly to the p-side electrode 11 in the first embodiment described above. However, since the surface emitting LED 10A in this embodiment is a p-side emission type, as shown in FIG. 15, the p-side electrode 11A on the mesa 15 does not prevent the p-side electrode 11A from interfering with light emission. An emission port L2 for taking out the emission light L in a mesh shape is formed. Here, in consideration of the diffusion length of the holes injected from the p-side electrode 11A, the exit L2 is formed at such a position and size that the holes are spread over the entire active layer 1 of the mesa 15. In addition, the shape of the radiation | emission outlet L2 is not limited to the shape shown in FIG. 15, It can be set as arbitrary shapes.

  Further, unlike the n-side electrode 12 in the first embodiment described above, the n-side electrode 12A is formed to cover the entire surface of the n-side. The p-side electrode 11A and the n-side electrode 12A are each made of a metal material, and include at least one of Ti, Cr, Mo, W, Ni, Pt, Cu, Ag, and Au. ing. For example, the p-side electrode 11A and the n-side electrode 12A can be a multilayer metal film in which a Ti film, a Pt film and an Au film are sequentially stacked.

In the present embodiment, a part of the p-side electrode 11A and a part of the n-side electrode 12A are reflection members that play the role of mirrors for reflecting light. Specifically, the p-side electrode 11A includes a first reflecting member that covers the side surface of the mesa 15, and the n-side electrode 12A is a light extraction direction of the two outer surfaces facing in the stacking direction of the mesa 15. It includes a second reflecting member that covers the opposite surface (the surface on the n-type semiconductor layer 3 side) via the substrate 14. In the following description of the present embodiment, the p-side electrode 11A is also referred to as a first metal mirror electrode 11A, and the n-side electrode 12A is also referred to as a second metal mirror electrode 12A.
In addition, since the manufacturing method of surface emitting type LED 10A in this embodiment is substantially the same as the manufacturing method of surface emitting type LED 10 in 1st embodiment mentioned above, description is abbreviate | omitted.

FIG. 16 is a schematic view showing a cross section of the surface-emitting type LED 10A in the present embodiment. In this FIG. 16, the same code | symbol is attached | subjected to the part which has the structure same as surface emitting type LED 10 in 1st embodiment mentioned above, and the description is abbreviate | omitted.
The surface-emitting type LED 10A is so-called junction-up mounting in which the light emitting unit 13 is mounted on a side far from the heat sink 20. In the surface emitting LED 10A, the light emitted from the active layer 1 is an n-type semiconductor which is opposite to the light extraction direction (upward direction in FIG. 16) of the p-type semiconductor layer 2 which is the light extraction direction. The light is propagated in the direction of the layer 3 (downward direction in FIG. 16) and in the lateral direction (horizontal direction in FIG. 16) of the active layer 1 which is a direction orthogonal to the light extraction direction. Among these, the light propagated to the n-type semiconductor layer 3 side is reflected to the p-type semiconductor layer 2 side by the second metal mirror electrode (second reflection member) 12A. Further, the light propagated in the lateral direction of the active layer 1 is reflected by the first metal mirror electrode (first reflective member) 11A on the side of the active layer 1 and returned to the active layer 1.

As described above, the surface-emitting type LED 10A in the present embodiment includes the first metal mirror electrode 11A covering the side surface of the semiconductor stack 15 and the second metal cover electrode covering the surface of the semiconductor stack 15 opposite to the light extraction direction. And a metal mirror electrode 12A. Therefore, among the light emitted from the active layer 1, the light propagated to other than the p-type semiconductor layer 2 may be emitted as the emitted light L together with the light propagated to the p-type semiconductor layer 2. it can. Therefore, compared with the case where the metal mirror electrode 11A and the metal mirror electrode 12B are not provided, uniform output light L with high output and high efficiency can be easily obtained.
In the present embodiment, the second reflection member that covers the surface (surface on the n-type semiconductor layer 3 side) opposite to the light extraction direction of the two outer surfaces facing in the stacking direction of the mesas 15 is n Although the case where it doubles as the side electrode 12A is described, a second reflecting member may be provided separately from the n-side electrode 12A. In that case, the second reflection member may be disposed at a position covering the surface on the n-type semiconductor layer 3 side, and may be disposed, for example, between the substrate 14 and the n-type semiconductor layer 3.

(Modification)
Although the case where the wavelength of the emitted light L is 1000 nm-1650 nm was demonstrated in said each embodiment, the wavelength of the emitted light L is not limited above, The surface emission which radiates | emits the emitted light of arbitrary wavelengths It is applicable to type LED. In that case, the material of the substrate 14 is appropriately selected according to the wavelength of the outgoing light L. For example, the substrate 14 is not limited to the InP substrate, but may be a GaAs substrate or a GaN substrate. However, in the case of a GaAs substrate, application to a p-side emission type surface-emitting LED is desirable from the viewpoint of light absorption in the substrate.

In each of the above embodiments, the case where the surface emitting semiconductor light emitting device is a surface emitting LED has been described, but the present invention can be applied to a surface emitting laser. However, in the case of the surface emitting laser, the stimulated emission light generated in the active layer forms a resonance mode by repeating multiple reflection in the direction perpendicular to the substrate surface, and is amplified and emitted. Therefore, when the resonant mode overlaps with the reflection member provided on the side of the active layer, the resonant mode is adversely affected, which may lead to an optical loss. On the other hand, in the case of the surface-emitting type LED described above, since only spontaneous emission light is emitted, there is no light loss as described above. Therefore, although the present invention is applicable also to a surface emitting type laser, application to a surface emitting type LED is preferred.
In each of the above-described embodiments, covering includes the case where a portion not covered by a part is provided other than the case where the outer surface of the substantially cylindrical portion is completely covered.

DESCRIPTION OF SYMBOLS 1 ... Active layer, 2 ... p-type semiconductor layer, 3 ... n-type semiconductor layer, 4 ... Contact layer, 5 ... insulating layer, 5a .. opening part, 10 ... surface emitting type light emitting diode (LED), 11 ... p side electrode (Metal mirror electrode), 11A: p side electrode (metal mirror electrode), 12: n side electrode, 12A: n side electrode (metal mirror electrode), 13: light emitting portion, 14: substrate, 15: semiconductor laminate (mesa ), 20 ... heat sink

Claims (13)

a multilayer semiconductor laminate including a p-type semiconductor layer, an n-type semiconductor layer, and an active layer disposed between the p-type semiconductor layer and the n-type semiconductor layer;
A p-side electrode formed on the outer surface of the p-type semiconductor layer side of the semiconductor laminate;
An n-side electrode formed on the outer surface of the n-type semiconductor layer side of the semiconductor stack;
A first reflecting member covering a side surface of the semiconductor laminate;
What is claimed is: 1. A surface-emitting type semiconductor light emitting device comprising: a second reflection member covering any one of two outer surfaces facing in the stacking direction of the semiconductor stack.   2. The surface emitting semiconductor light emitting device according to claim 1, wherein the second reflection member is provided on a surface of the two outer surfaces opposite to the light extraction direction.   The surface emitting semiconductor light emitting device according to claim 1 or 2, wherein a light extraction direction is a direction toward the side where the n-type semiconductor layer is disposed with respect to the active layer in the stacking direction. .   The said 1st reflection member and a said 2nd reflection member are continuously integrally formed on the said semiconductor laminated body, The any one of Claim 1 to 3 characterized by the above-mentioned. Surface emitting semiconductor light emitting device.   The surface-emitting semiconductor light-emitting device according to any one of claims 1 to 4, wherein the first reflecting member and the second reflecting member are made of a metal material.   The surface-emitting type semiconductor light-emitting device according to any one of claims 1 to 5, wherein the second reflection member doubles as any one of the p-side electrode and the n-side electrode.   The surface according to any one of claims 1 to 6, wherein the p-side electrode and the n-side electrode are formed at positions not overlapping with each other when viewed in the stacking direction of the semiconductor laminate. Light emitting semiconductor light emitting device.   The surface emission according to any one of claims 1 to 7, wherein a shape of the semiconductor laminated body covered by the first reflecting member is a cylindrical shape having the laminating direction as an axial direction. Semiconductor light emitting device.   The surface emitting semiconductor light emitting device according to any one of claims 1 to 7, further comprising an insulating layer disposed between a side surface of the semiconductor laminate and the first reflecting member. The insulating layer is further formed on the periphery of the outer surface on the p-type semiconductor layer side,
The surface-emitting type semiconductor light emitting device according to claim 9, wherein the p-side electrode is connected to a region of the outer surface on the p-type semiconductor layer side where the insulating layer is not formed.   The surface emitting semiconductor light emitting device according to any one of claims 1 to 10, further comprising an InP substrate in which the semiconductor laminate is formed on a main surface.   The surface emitting semiconductor light emitting device according to any one of claims 1 to 11, wherein the surface emitting semiconductor light emitting element is a surface emitting light emitting diode. A side surface of a multilayer semiconductor laminate including a p-type semiconductor layer, an n-type semiconductor layer, and an active layer disposed between the p-type semiconductor layer and the n-type semiconductor layer is formed by a first reflecting member. Covering step,
A method of manufacturing a surface emitting semiconductor light emitting device, comprising: covering any one of two outer surfaces facing each other in the stacking direction of the semiconductor stack with a second reflecting member.

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