JP2009117599A - Semiconductor light emitting device - Google Patents

Abstract

Provided is a semiconductor light emitting device capable of reducing the detection level of spontaneous emission light and dark current by a semiconductor photodetecting element without impairing the reliability of the element, thereby further improving the photodetection accuracy. .
A semiconductor light emitting device includes a lower DBR layer, a lower spacer layer, an active layer, an upper spacer layer, a current confinement layer, an upper DBR layer, and a contact layer in that order from the substrate side. The columnar mesa portion M1 including the light exit window 28A is provided on the contact layer 27. The semiconductor photodetecting element 30 is formed integrally with the mesa unit M1 on the side opposite to the light exit window 28A of the mesa unit M1, and includes the first conductive type semiconductor layer 31, the photodetecting layer 32, and the second conductive type semiconductor layer. It has a laminated structure including 33 and 34 in order from the substrate 10 side. The width L2 of the light detection layer 32 is narrower than the width L3 of the mesa portion M1.
[Selection] Figure 2

Description

  The present invention relates to a semiconductor light emitting device having a semiconductor light detection element that detects emitted light, and more particularly to a semiconductor light emitting device that can be suitably applied in applications that require a high degree of light detection accuracy.

  2. Description of the Related Art Conventionally, semiconductor light emitting devices for applications such as optical fibers and optical disks have a light detection mechanism that emits light emitted from a semiconductor light emitting element as part of the purpose of keeping the light output level of the semiconductor light emitting element incorporated therein. It is done to detect. This light detection mechanism can be constituted by, for example, a reflection plate that branches a part of the emitted light and a semiconductor light detection element that detects the branched emitted light. However, in this case, not only the number of parts increases, but also there is a problem that the reflector and the semiconductor light detection element must be arranged with high accuracy with respect to the semiconductor light emitting element. Therefore, as one of the measures for solving such a problem, it is conceivable to integrally form the semiconductor light emitting element and the semiconductor light detecting element.

  However, if these are integrally formed, the semiconductor light detection element may detect not only the stimulated emission light that should be detected but also the spontaneous emission light. In such a case, an error corresponding to the spontaneous emission light is included in the light output level of the semiconductor light emitting element measured based on the light detected by the semiconductor light detecting element. Therefore, this method is also not suitable for applications where the light output level is required to be controlled with high accuracy.

  Therefore, Patent Document 1 proposes a technique in which a control layer is provided in the semiconductor light detection element and a part of the spontaneous emission light input from the semiconductor light emitting element is blocked before the semiconductor light detection element detects it.

Japanese Patent No. 2877785

  By the way, the above-mentioned control layer is formed by oxidizing a part of the semiconductor material constituting the semiconductor photodetecting element. In order to block the spontaneous emission light by the oxidized semiconductor material, it is necessary to increase the film thickness. However, if the film thickness is too large, the reliability of the element is impaired due to distortion of volume shrinkage due to oxidation. there is a possibility.

  Further, the semiconductor photodetecting element generally has a sandwich structure in which a photodetecting layer made of a non-doped semiconductor is sandwiched between a pair of semiconductor layers having different conductivity types. However, in such a structure, all the side surfaces of the light detection layer are exposed at the end surface. Therefore, when a reverse bias is applied to the semiconductor photodetecting element, a dark current flows through a portion of the photodetecting layer exposed at the end face, which may reduce the photodetection accuracy.

  The present invention has been made in view of such problems, and its purpose is to reduce the detection level of spontaneous emission light and dark current by the semiconductor photodetecting element without impairing the reliability of the element, thereby detecting light. An object of the present invention is to provide a semiconductor light emitting device capable of further improving accuracy.

  The semiconductor light emitting device of the present invention comprises a semiconductor light emitting element and a semiconductor light detecting element on one surface side of a semiconductor substrate. The semiconductor light emitting device includes a first multilayer film reflector, an active layer including a light emitting region, and a second multilayer film reflector in order from the semiconductor substrate side, and also emits light emitted from the light emitting region to the second multilayer film reflector side. It has a columnar first laminated structure including a light exit window that mainly emits light. The semiconductor photodetecting element is integrally formed with the first laminated structure on the light emitting window side of the first laminated structure or on the side opposite to the light emitting window, and the first conductive type semiconductor layer, the photodetecting layer, and the second The semiconductor device has a second stacked structure including conductive semiconductor layers in order from the semiconductor substrate side. Here, the photodetection layer has a width narrower than the width of the first laminated structure in the one direction in one direction within the lamination plane of the photodetection layer.

  In the semiconductor light emitting device of the present invention, the width in one direction in the stacked surface of the light detection layer is narrower than the width in the one direction of the first stacked structure. As a result, most of spontaneous emission light having a wide divergence angle included in the light output from the semiconductor light emitting element passes through a portion other than the light detection layer. Further, all the side surfaces of the light detection layer are not exposed to the end face of the semiconductor light emitting device.

  According to the semiconductor light emitting device of the present invention, the width in one direction in the stacked surface of the light detection layer is made narrower than the width in the one direction of the first stacked structure. Since the detection level of the spontaneous emission light and the dark current can be reduced, the light detection accuracy can be further improved. In addition, since an oxidized semiconductor is not used to block spontaneously emitted light, the reliability of the element is not impaired.

  Hereinafter, embodiments of the present invention will be described in detail with reference to the drawings.

[First Embodiment]
FIG. 1 shows a top configuration of the semiconductor light emitting device 1 according to the first embodiment of the present invention, and FIG. 2 shows a cross sectional configuration of the semiconductor light emitting device 1 in FIG. . 3A and 3B show a top surface configuration and a cross-sectional configuration of the semiconductor substrate 10. FIGS. 1 to 3A and 3B are schematic representations, and are different from actual dimensions and shapes.

  In this semiconductor light emitting device 1, a semiconductor light detection element 30 and a surface light emission type semiconductor light emitting element 20 are sequentially arranged on one surface side of a semiconductor substrate 10 from the semiconductor substrate 10 side, and these semiconductor light detection elements are arranged. 30 and the semiconductor light emitting element 20 are integrally formed.

(Semiconductor substrate 10)
The semiconductor substrate 10 is made of, for example, a p-type GaAs substrate having a {100} plane (for example, (100) plane) as a main surface. Examples of p-type impurities include zinc (Zn), magnesium (Mg), and beryllium (Be).

  The semiconductor substrate 10 has a convex portion 10 </ b> A extending in one direction within the surface, for example, the <110> direction, in the surface on the semiconductor light emitting element 20 and semiconductor light detection element 30 side. The convex portion 10A is formed to extend from one end surface of the semiconductor substrate 10 to the other end surface, and a pair of end surfaces (side surfaces) of the convex portion 10A facing the extending direction of the convex portion 10A. Is formed in the same plane as the end face of the semiconductor substrate 10. On the other hand, a pair of end surfaces (side surfaces) 10 </ b> D facing the direction orthogonal to the extending direction of the convex portion 10 </ b> A of the convex portion 10 </ b> A are formed inside the end surface of the semiconductor substrate 10. That is, the convex portion 10 </ b> A is formed on a part of one surface of the semiconductor substrate 10.

  The upper surface 10B of the convex portion 10A is a rectangular flat surface, and is parallel to the upper surface 10C of the upper surface of the semiconductor substrate 10 where the convex portion 10A is not formed. Both the upper surface 10B and the upper surface 10C are, for example, {100} planes (for example, (100) planes).

  Note that the width L1 of the upper surface 10B in the direction orthogonal to the extending direction of the convex portion 10A is narrower than the width L3 of the mesa portion M1 of the semiconductor light emitting element 20 described later in the width direction of the convex portion 10A. Is preferred. Further, the end surface 10D of the convex portion 10A may be an inclined surface that intersects the upper surface 10B of the convex portion 10A at an obtuse angle as shown in FIGS. 1 to 3A and 3B. However, it may intersect the upper surface 10B of the convex portion 10A at an acute angle or may intersect the upper surface 10B of the convex portion 10A perpendicularly.

(Semiconductor photodetecting element 30)
The semiconductor photodetecting element 30 is formed in contact with the semiconductor substrate 10, and the first conductive semiconductor layer 31, the photodetecting layer 32, the second conductive semiconductor layer 33, the current blocking layer 34, on the semiconductor substrate 10. It has a laminated structure (second laminated structure) including the second conductivity type semiconductor layer 35.

  The first conductivity type semiconductor layer 31, the light detection layer 32, and the second conductivity type semiconductor layer 33 are formed (substantially) separated from each other on the upper surface 10B and the upper surface 10C of the upper surface of the semiconductor substrate 10. A portion of the first conductive semiconductor layer 31, the light detection layer 32, and the second conductive semiconductor layer 33 formed on the upper surface 10B side extends in a direction parallel to the extending direction of the convex portion 10A. It has a belt-like convex shape and has inclined surfaces 30A that form a predetermined inclination angle α with the upper surface 10B on both side surfaces. For example, as will be described later, the inclined surface 30A is naturally formed by crystal growth of a semiconductor on the upper surface 10B of the convex portion 10A, and the inclination angle α is approximately 55 degrees. Therefore, the width of the convex portion 10A in the width direction of the portion formed on the upper surface 10B side of the first conductive semiconductor layer 31, the light detection layer 32, and the second conductive semiconductor layer 33 is equal to the width L1 of the upper surface 10B. It is equal or narrower than that.

  Here, the first conductivity type semiconductor layer 31 is made of, for example, p-type GaAs, and has a strip shape extending in a direction parallel to the extending direction of the convex portion 10A.

  The light detection layer 32 is for absorbing the light of the semiconductor light emitting element 20 and converting it into an electrical signal (photocurrent) corresponding to the output level of the absorbed light, and is made of undoped GaAs, for example. An electrical signal generated in the light detection layer 32 is input as a light output monitor signal to a light output operation circuit (not shown) connected to a common electrode 36 and a lower electrode 39 described later. It is used to measure the output level of laser light emitted from the light exit window 28A.

  The light detection layer 32 has a strip shape extending in a direction parallel to the extending direction of the convex portion 10A. The width L2 of the convex portion 10A in the width direction of the portion formed on the upper surface 10B side of the light detection layer 32 is narrower than the width L3 of the mesa portion M1 of the semiconductor light emitting element 20 in the width direction of the convex portion 10A. The light emitting region 23A of the semiconductor light emitting device 20 is preferably equal to or narrower than the width L4 in the width direction of the convex portion 10A.

  The second conductivity type semiconductor layer 33 is made of a semiconductor having a conductivity type different from that of the first conductivity type semiconductor layer 31, for example, n-type AlGaAs. Examples of n-type impurities include silicon (Si) and selenium (Se). Therefore, the semiconductor photodetecting element 30 has a sandwich structure in which the photodetecting layer 32 is sandwiched between semiconductor layers having different conductivity types.

  The current blocking layer 34 is for electrically separating the first conductive semiconductor layer 31 and the light detection layer 32 from the second conductive semiconductor layer 35 formed on the current blocking layer 34. The current blocking layer 34 includes a side surface of the first conductive semiconductor layer 31, the light detection layer 32, and the second conductive semiconductor layer 33 formed on the upper surface 10 </ b> B side, the first conductive semiconductor layer 31, the light The detection layer 32 and the second conductivity type semiconductor layer 33 are formed in contact with the surface of the portion formed on the upper surface 10C side. For example, the p-type semiconductor layer, the n-type semiconductor layer, and the p-type semiconductor layer are formed on the upper surface. The layers are stacked in order from the 10C side.

  The second conductivity type semiconductor layer 35 is formed in contact with a portion of the second conductivity type semiconductor layer 33 formed on the upper surface 10B side. The second conductive semiconductor layer 35 is made of, for example, n-type AlGaAs, and is electrically connected to a portion of the second conductive semiconductor layer 33 formed on the upper surface 10B side.

  The semiconductor light emitting element 20 is formed integrally with the semiconductor photodetecting element 30 in a region including the region facing the convex portion 10 </ b> A on the upper surface of the second conductive semiconductor layer 35. A common electrode 36 is formed around the semiconductor light emitting element 20 on the upper surface. An insulating film 37 is formed on the side surface of the semiconductor light emitting element 20 and the surface of the upper surface of the second conductivity type semiconductor layer 35 where the semiconductor light emitting element 20 and the common electrode 36 are not formed. On the surface of the insulating film 37, an electrode pad 38 electrically connected to the common electrode 36 is formed. Further, a lower electrode 39 is formed on the back surface of the semiconductor substrate 10.

Here, the common electrode 36 and the electrode pad 38 are, for example, an alloy of gold (Au) and germanium (Ge), nickel (Ni), and gold (Au) stacked in this order from the second conductivity type semiconductor layer 35 side. The structure is electrically connected to the second conductivity type semiconductor layer 35. The lower electrode 39 has a structure in which, for example, titanium (Ti), platinum (Pt), and gold (Au) are stacked in this order from the semiconductor substrate 10 side, and is electrically connected to the semiconductor substrate 10. The insulating film 37 is for protecting the mesa portion M1, and is made of an insulating material such as silicon oxide (SiO ₂ ) or silicon nitride (SiN), for example.

(Semiconductor light emitting element 20)
The semiconductor light emitting device 20 includes a lower DBR layer 21, a lower spacer layer 22, an active layer 23, an upper spacer layer 24, a current confinement layer 25, and an upper DBR layer 26 on the second conductive semiconductor layer 35 of the semiconductor photodetector 30. The contact layer 27 and the upper electrode 28 are stacked in order from the second conductive semiconductor layer 35 side (first stacked structure).

  In this stacked structure, the lower DBR layer 21, the lower spacer layer 22, the active layer 23, the upper spacer layer 24, the current confinement layer 25, the upper DBR layer 26, and the contact layer 27 are columnar mesa portions having a central axis in the stacking direction. The upper electrode 28 is provided with an opening as a light exit window 28 that mainly outputs the light emitted from the active layer 23 to the outside in a central region including the central axis of the mesa portion M1.

The lower DBR layer 21 is configured by alternately laminating a low refractive index layer (not shown) and a high refractive index layer (not shown), and activates most of the light emitted from the active layer 23. While reflecting to the layer 23 side, the light emitted from the active layer 23 is slightly transmitted to the semiconductor photodetector element 30 side. Here, an n-type _Al x1 _Ga 1-x1 As the low refractive index layer is, for example, optical thickness is λ _1/4 (λ ₁ is an oscillation wavelength) (0 <x1 <1) , the high refractive index layer is, for example, comprises an optical thickness is λ _1/4 n-type _{Al x2 Ga 1-x2 As (} 0 ≦ x2 <x1). The lower spacer layer 22 is made of, for example, n-type Al _x3 Ga _1-x3 As (0 ≦ x3 <1).

  The active layer 23 is made of, for example, a GaAs material. In the active layer 23, a central portion (a region facing a current injection region 25B described later) of the active layer 23 in the stacked in-plane direction becomes a light emitting region 23A.

The upper spacer layer 24 is made of, for example, p-type Al _x4 Ga _1-x4 As (0 ≦ x4 <1). The upper DBR layer 26 is configured by alternately laminating a low refractive index layer (not shown) and a high refractive index layer (not shown), and activates most of the light emitted from the active layer 23. While reflecting to the layer 23 side, a part of the light emitted from the active layer 23 is transmitted to the light exit window 28A side. Here, it made a low refractive index layer is, for example, optical thickness of lambda _1/4 p-type _{Al x5 Ga 1-x5 As (} 0 <x5 <1), the high refractive index layer is, for example, optical thickness of lambda ₁ / 4 p-type Al _x6 Ga _1-x6 As (0 ≦ x6 <x5). The contact layer 27 is made of, for example, p-type Al _x7 Ga _1-x7 As (0 ≦ x7 <1).

The current confinement layer 25 has a current confinement region 25A in a region from the side surface of the mesa portion M1 to a predetermined depth, and the other region (the central region of the mesa portion M1) is a current injection region 25B. The current injection region 25B is made of, for example, p-type Al _x8 Ga _1-x8 As (0 <x8 ≦ 1). The current confinement region 25A includes, for example, Al ₂ O ₃ (aluminum oxide), and is obtained by oxidizing high-concentration Al contained in the oxidized layer 25D from the side surface, as will be described later. . Therefore, the current confinement layer 25 has a function of confining current.

  The mesa portion M1 is formed at a position where its central axis intersects the center line in the width direction of the convex portion 10 or its vicinity region, and has, for example, a cylindrical shape with a diameter of about 40 μm. This diameter is appropriate according to the oxidation rate, oxidation time, etc. in the oxidation step so that an unoxidized region (current injection region 25B) of a predetermined size remains in the mesa portion M1 in the oxidation step described later. Has been adjusted.

  The semiconductor light emitting device 1 having such a configuration can be manufactured, for example, as follows.

  4A and 4B to 12 show the manufacturing method in the order of steps. 4A, FIG. 5A, FIG. 6A, FIG. 7, FIG. 9, and FIG. 11 show the top surface configuration of the device in the manufacturing process. 4B is a cross-sectional configuration in the direction of arrows AA in FIG. 4A, FIG. 5B is a cross-sectional configuration in the direction of arrows AA in FIG. (B) is a cross-sectional configuration in the direction of arrows AA in FIG. 6 (A), FIG. 8 is a cross-sectional configuration in the direction of arrows AA in FIG. 7, and FIG. 10 is a direction in the direction of arrows AA in FIG. FIG. 12 shows a cross-sectional configuration in the direction of arrows AA in FIG.

In order to manufacture the semiconductor light emitting device 1, a GaAs compound semiconductor is formed on a substrate 10 made of GaAs having a (100) plane as a main surface, for example, MOCVD (Metal Organic Chemical Vapor Deposition) method. It forms in a lump by the epitaxial crystal growth method. At this time, as a raw material for the GaAs compound semiconductor, for example, a methyl organic metal gas such as trimethylaluminum (TMA), trimethylgallium (TMG), TMIn (trimethylindium), or arsine (AsH ₃ ) is used. For example, hydrogen selenide (H2 Se) is used as the raw material, and dimethyl zinc (DMZn) is used as the acceptor impurity raw material, for example.

  Specifically, first, a strip-like resist that extends in the <110> direction on the (100) surface of the substrate 10 and extends from one end surface of the substrate 10 to another end surface facing the end surface. The layer R1 is formed (FIGS. 4A and 4B).

  Next, the substrate 10 is selectively etched using the resist layer R1 as a mask. As a result, a belt-like convex portion 10A extending from one end surface of the substrate 10 to the other end surface facing the end surface is formed immediately below the resist layer R1 (FIGS. 5A and 5B). . At this time, the (100) plane is exposed on both the upper surface 10B of the convex portion 10A and the surrounding upper surface 10C.

  Next, after removing the resist layer R1, the first conductivity type semiconductor layer 31, the light detection layer 32, and the second conductivity type semiconductor layer 33 are stacked on the surface including the convex portion 10A. At this time, the non-growth surface of the (111) B surface occurs from the end of the upper surface 10B of the convex portion 10A, and the crystal growth stops sequentially from the end of the upper surface 10B of the convex portion 10A. As a result, the crystal growth on the convex portion 10A includes a non-growth surface generated from one end portion of the upper surface 10B of the convex portion 10A and a non-growth surface generated from the other end portion of the upper surface 10B of the convex portion 10A. Stop when they cross each other. As a result, a pair of inclined surfaces 30A having an inclination angle α is formed on the upper surface of the convex portion 10A (FIGS. 6A and 6B).

  Subsequently, on the surface including the inclined surface 30A, the current blocking layer 34, the second conductivity type semiconductor layer 35, the lower DBR layer 21, the lower spacer layer 22, the active layer 23, the upper spacer layer 24, the oxidized layer 25D, the upper portion A DBR layer 26 and a contact layer 27 are stacked (FIGS. 7 and 8).

  Next, after forming the circular resist layer R2 on the upper surface of the contact layer 27 and in the region through which the center line in the width direction of the convex portion 10A passes (FIGS. 9 and 10), the resist layer R2 is formed. As a mask, the lower DBR layer 21, the lower spacer layer 22, the active layer 23, the upper spacer layer 24, the oxidized layer 25D, the upper DBR layer 26, and the contact layer 27 are selectively etched. As a result, a mesa portion M1 is formed immediately below the resist layer R2 (FIGS. 11 and 12).

  Next, an oxidation process is performed at a high temperature in a water vapor atmosphere to selectively oxidize the oxidized layer 25D from the side surface of the mesa M1. As a result, the outer edge region of the oxidized layer 25D becomes an insulating layer (aluminum oxide). As a result, the current confinement region 25A is formed in the outer edge region, and the central region becomes the current injection region 25B. Thus, the current confinement layer 25 is formed (FIG. 2).

  Next, after forming the insulating film 37, the upper electrode 28 is formed on the contact layer 27 by, for example, vapor deposition, and the common electrode 36 is formed on the exposed portion of the second conductivity type semiconductor layer 33 (FIG. 2). . Further, the lower electrode 39 is formed on the back surface of the semiconductor substrate 10 (FIG. 1). In this way, the semiconductor light emitting device 1 of the present embodiment is manufactured.

In the semiconductor light emitting device 1 according to the present embodiment, for example, the common electrode 36 is used as a common ground for the semiconductor light emitting element 20 and the semiconductor light detecting element 30, and a current for driving the semiconductor light emitting element 20 is supplied from the upper electrode 28. When a reverse bias is applied to the lower electrode 39, the current confined by the current confinement layer 25 is injected into the light emitting region 23A, which is the gain region of the active layer 23, thereby emitting light by recombination of electrons and holes. Arise. This light includes not only stimulated emission light but also spontaneous emission light. However, as a result of repeated stimulated emission in the device, laser oscillation occurs at a predetermined wavelength λ ₁ , and light A including wavelength λ ₁ is generated. The light is mainly output from the light exit window 28A and emitted to the outside, and is slightly output from the lower DBR layer 21 to the semiconductor light detection element 30 side, and a part of the light enters the light detection layer 32 (FIG. 13).

  The light incident on the photodetection layer 32 is absorbed by the photodetection layer 32 and converted into an electric signal (photocurrent) corresponding to the output level of the absorbed light, and then the electric signal is the common electrode 36 and the lower electrode 39. Is output to an optical output arithmetic circuit (not shown) via a wire (not shown) electrically connected to the optical output, and then received as an optical output monitor signal in the optical output arithmetic circuit. Thereby, the output level of the light incident on the light detection layer 32 is measured.

  By the way, in the present embodiment, the width L2 of the convex portion 10A in the width direction of the light detection layer 32 is at least narrower than the width L3 of the mesa portion M1 in the width direction of the convex portion 10A. As a result, most of spontaneous emission light having a wide divergence angle included in the light A slightly output from the semiconductor light emitting element 20 to the semiconductor light detection element 30 side passes through portions other than the light detection layer 32. On the other hand, the stimulated emission light included in the light slightly output from the semiconductor light emitting element 20 to the semiconductor light detecting element 30 has high directivity, and most of the light is the light detecting layer 32 immediately below the light emitting region 23A. Is incident on. As a result, the amount of spontaneous emission light incident on the light detection layer 32 can be made extremely small compared to the amount of stimulated emission light incident on the light detection layer 32. Accordingly, since the spontaneous emission light can be effectively prevented from entering the light detection layer 32, the detection level of the spontaneous emission light by the semiconductor light detection element 30 can be reduced. As a result, the stimulated emission light can be reduced. The light detection accuracy can be further improved.

  When the width L2 of the convex portion 10A in the width direction of the light detection layer 32 is (almost) equal to the width L3 of the light emitting region 23A in the width direction of the convex portion 10A, the loss of stimulated emission light is minimized. Since the limit can be set, the output level of the electric signal can be increased and the S / N can be improved.

  In the present embodiment, the structure (photodetection layer 32) for removing spontaneously emitted light is formed on the semiconductor substrate 10 having the convex portion 10A by using a crystal growth method such as MOCVD. For example, as in Patent Document 1, the shape and size of the semiconductor layer are larger than those in the case where an oxide layer that prevents transmission of spontaneous emission light is formed by oxidizing a part of the semiconductor layer using an oxidation process that is not easily controlled. Can be formed with high accuracy. Thereby, the dispersion | variation in the characteristic for every semiconductor light-emitting device can be made very small.

  Further, in order to remove spontaneously emitted light, there is no need to use a process in which volume shrinkage such as oxidation of the semiconductor layer occurs as in Patent Document 1, for example. Thereby, there is no possibility that the semiconductor photodetecting element 30 may be peeled off due to the volume shrinkage distortion, so that the semiconductor light detection element 30 is compared with the case where a layer that removes spontaneous emission light is formed using a process that causes volume shrinkage such as oxidation of the semiconductor layer. Yield and reliability are extremely high.

  In the present embodiment, the width L2 of the convex portion 10A in the width direction of the light detection layer 32 is at least smaller than the width L3 of the mesa portion M1 in the width direction of the convex portion 10A. All 32 side surfaces are not exposed to the end face of the semiconductor light emitting device 1. Thereby, when a reverse bias is applied to the semiconductor photodetecting element 30, the magnitude of the dark current flowing through the portion exposed to the end face of the photodetecting layer 32 is determined by the side face of the photodetecting layer. Compared with the case where it is exposed to the light, it can be greatly reduced. As a result, the light detection accuracy of stimulated emission light can be further improved.

  Further, the first conductive type semiconductor layer 31 to the contact layer 27 can be collectively formed by the epitaxial crystal growth method. As a result, the manufacturing process can be simplified and the time required for manufacturing can be shortened as compared with the case where the structure for removing spontaneously emitted light is formed using another method.

  In the present embodiment, since the semiconductor light detection element 30 is provided on the side opposite to the side from which the light of the semiconductor light emitting element 20 is mainly emitted to the outside (light emission window 28A), the semiconductor light detection element 30 is provided. The space to be provided is not limited by the size of the mesa portion M1. Thereby, the semiconductor photodetecting element 30 can be formed more easily than the case where the semiconductor photodetecting element 30 is provided on the side from which the light of the semiconductor light emitting element 20 is mainly emitted to the outside (light emission window 28A).

[Modification of First Embodiment]
In the above embodiment, the pair of end faces of the photodetection layer 32 facing the extending direction of the photodetection layer 32 are formed in the same plane as the end face of the semiconductor substrate 10. Alternatively, it may be formed inside the end surface of the semiconductor substrate 10. In such a case, when the first conductive semiconductor layer 31 or the like is formed on the surface including the convex portion 10A in the manufacturing process, the pair of end faces are formed by the first conductive semiconductor layer 31 or the like. Covered and no longer exposed to the outside. Thereby, since no dark current flows through the photodetection layer 32, the photodetection accuracy of the stimulated emission light can be further improved.

  By the way, as described above, in order to cover the end surface of the light detection layer 32 with the first conductive type semiconductor layer 31 or the like, the end surface of the convex portion 10A of the semiconductor substrate 10 is made to be more than the end surface of the semiconductor substrate 10. What is necessary is just to form inside. At that time, for example, as shown in FIG. 14, the length in the extending direction of the convex portion 10 </ b> A may be narrower than the width of the semiconductor substrate 10, or as shown in FIGS. 15, 16, and 17. Thus, not only the length of the protruding portion 10A in the extending direction is made narrower than the width of the semiconductor substrate 10, but also the shape of the protruding portion 10A may be a shape other than the band shape. For example, as shown in FIG. 15, when the cross-sectional shape in the in-plane direction of the convex portion 10A is circular, the cross-sectional shape in the in-plane direction of the photodetecting layer 32 is also circular (similar). Become. For example, as shown in FIG. 16, when the cross-sectional shape in the in-plane direction of the convex portion 10 </ b> A is elliptical, the cross-sectional shape in the in-plane direction of the light detection layer 32 is also elliptical (similar) ) For example, as shown in FIG. 17, when the cross-sectional shape in the in-plane direction of the convex portion 10 </ b> A is a polygonal shape, the cross-sectional shape in the in-plane direction of the light detection layer 32 is also a polygonal shape (similar shape). )

[Second Embodiment]
FIG. 18 shows the top surface configuration of the semiconductor light emitting device 2 according to the second embodiment of the present invention, and FIG. 19 shows the cross sectional configuration of the semiconductor light emitting device 2 in FIG. . 18 and 19 are schematically shown and are different from actual dimensions and shapes. Moreover, in the following description, when the same code | symbol as the said embodiment is used, it has having the structure and function similar to the element of the same code | symbol. In the following description, configurations, operations, and effects different from those in the above embodiment will be mainly described, and descriptions of configurations, operations, and effects common to the above embodiments will be omitted as appropriate.

  In this semiconductor light emitting device 2, the semiconductor light detecting element 50 is integrally formed on the light emitting window 53 </ b> A side of the semiconductor light emitting element 40, and the semiconductor light detecting element 30 is different from the light emitting window 28 </ b> A of the semiconductor light emitting element 20. This is different from the configuration of the semiconductor light emitting device 1 integrally formed on the opposite side.

(Semiconductor light emitting element 40)
The semiconductor light emitting device 40 includes a lower DBR layer 41, a current confinement layer 42, a lower spacer layer 43, an active layer 44, an upper spacer layer 45, an upper DBR layer 46, and a common electrode 47 on the upper surface 10B of the convex portion 10A of the semiconductor substrate 10. Are stacked in order from the semiconductor substrate 10 side (first stacked structure).

  In this stacked structure, the upper portion of the lower DBR layer 41, the current confinement layer 42, the lower spacer layer 43, the active layer 44, the upper spacer layer 45, and the upper DBR layer 46 constitute a columnar mesa portion M2 having a central axis in the stacking direction. In the central region including the central axis of the mesa portion M2, the common electrode 47 is provided with an opening as a light emission window 47A that mainly outputs the light emitted from the active layer 44 to the semiconductor light emitting element 40 side. .

The lower DBR layer 41 is configured by alternately laminating low refractive index layers (not shown) and high refractive index layers (not shown). Here, a p-type _Al x1 _Ga 1-x1 As the low refractive index layer is, for example, optical thickness is λ _1/4 (λ ₁ is an oscillation wavelength) (0 <x1 <1) , the high refractive index layer is, for example, comprises an optical thickness is λ _1/4 p-type _{Al x2 Ga 1-x2 As (} 0 ≦ x2 <x1). The lower spacer layer 43 is made of, for example, p-type Al _x3 Ga _1-x3 As (0 ≦ x3 <1).

  The active layer 44 is made of, for example, a GaAs material. In the active layer 44, a central portion (a region opposite to a current injection region 42B described later) in the in-plane direction of the active layer 44 is a light emitting region 44A.

The upper spacer layer 45 is made of, for example, n-type Al _x4 Ga _1-x4 As (0 ≦ x4 <1). The upper DBR layer 46 is configured by alternately laminating a low refractive index layer (not shown) and a high refractive index layer (not shown), and activates most of the light emitted from the active layer 44. While reflecting to the layer 44 side, a part of the light emitted from the active layer 23 is transmitted to the light exit window 47A side. Here, it made a low refractive index layer is, for example, optical thickness of lambda _1/4 n-type _{Al x5 Ga 1-x5 As (} 0 <x5 <1), the high refractive index layer is, for example, optical thickness of lambda ₁ / 4 n-type Al _x6 Ga _1-x6 As (0 ≦ x6 <x5).

The current confinement layer 42 has a current confinement region 42A in a region from the side surface of the mesa portion M2 to a predetermined depth, and the other region (the central region of the mesa portion M2) is a current injection region 42B. The current injection region 42B is made of, for example, p-type Al _x8 Ga _1-x8 As (0 <x8 ≦ 1). The current confinement region 42A includes, for example, Al ₂ O ₃ (aluminum oxide), and is obtained by oxidizing high concentration Al contained in the oxidized layer from the side surface in the manufacturing process. Therefore, the current confinement layer 42 has a function of confining current.

  The mesa portion M2 is formed at a position where its central axis intersects the center line in the width direction of the convex portion 10 or its vicinity region, and has a cylindrical shape with a diameter of about 40 μm, for example. The width L3 of the mesa portion M2 in the width direction of the convex portion 10A is narrower than the width L1 of the upper surface 10B because the semiconductor light emitting element 40 is formed on the upper surface 10B of the convex portion 10A.

(Semiconductor photodetecting element 50)
The semiconductor photodetecting element 50 is formed in contact with the semiconductor light emitting element 40 and has a stacked structure (second stacked structure) including the photodetecting layer 51 and the contact layer 52 on the upper DBR layer 46.

  The photodetection layer 51 has a columnar shape at the bottom, similar to the mesa portion M2. Further, the upper portion of the light detection layer 51 and the contact layer 52 have inclined surfaces 60A that form a predetermined inclination angle α with the upper surface 10B on both side surfaces. The inclined surface 60A is naturally formed, for example, by crystal growth of a semiconductor on the upper surface 10B of the convex portion 10A, and the inclination angle α is approximately 55 degrees. Therefore, the width in the width direction of the convex portion 10A of the light detection layer 51 and the contact layer 52 is narrower than the width L1 of the upper surface 10B.

  In addition, a region facing the light emitting region 48A in the upper surface of the contact layer 52 is, for example, a flat surface. This flat surface can be formed, for example, by stopping the crystal growth before the crystal growth on the upper surface 10B stops when the semiconductor is grown on the upper surface 10B of the convex portion 10A. Note that a ridge line formed when crystal growth on the upper surface 10B stops when the semiconductor is grown on the upper surface 10B of the convex portion 10A may be formed on the upper surface of the contact layer 52.

  The light detection layer 51 is for absorbing the light of the semiconductor light emitting element 40 and converting it into an electric signal (photocurrent) corresponding to the output level of the absorbed light, and is made of undoped GaAs, for example. The electrical signal generated in the light detection layer 51 is input as a light output monitor signal to a light output arithmetic circuit (not shown) connected to the common electrode 47 and the upper electrode 53, and light is emitted from the light output arithmetic circuit. This is used to measure the output level of the laser light emitted from the window 47A.

  The upper portion of the light detection layer 51 has a belt-like convex shape extending in a direction parallel to the extending direction of the convex portion 10A. The width L2 of the convex portion 10A in the width direction at the bottom of the light detection layer 51 is narrower than the width L3 of the mesa portion M2 of the semiconductor light emitting element 40 in the width direction of the convex portion 10A. It is preferable that the light emitting region 44A is equal to or narrower than the width L4 of the convex portion 10A in the width direction.

  In this semiconductor photodetecting element 50, the upper part of the upper DBR layer 46 also serves as one of the semiconductor layers having different conductivity types that sandwich the photodetecting layer 51.

In the semiconductor light emitting device 2 of the present embodiment, for example, the common electrode 46 is used as a common ground for the semiconductor light emitting element 40 and the semiconductor light detecting element 50, and a current for driving the semiconductor light emitting element 40 is supplied from the lower electrode 39. When a reverse bias is applied to the upper electrode 53, the current confined by the current confinement layer 42 is injected into the light emitting region 44A, which is the gain region of the active layer 44, and thereby light emission due to recombination of electrons and holes is generated. Arise. This light includes not only stimulated emission light but also spontaneous emission light. However, as a result of repeated stimulated emission in the device, laser oscillation occurs at a predetermined wavelength λ ₁ , and light A including wavelength λ ₁ is generated. While entering the light detection layer 51 through the light emission window 47A, the light transmitted through the light detection layer 51 is emitted to the outside from the opening of the upper electrode 53 (FIG. 20).

  Part of the light incident on the light detection layer 51 is absorbed by the light detection layer 51 and converted into an electric signal (photocurrent) corresponding to the output level of the absorbed light. After being output to an optical output arithmetic circuit (not shown) via a wire (not shown) electrically connected to the upper electrode 53, the optical output arithmetic circuit receives it as an optical output monitor signal. Thereby, the output level of the light incident on the light detection layer 51 is measured.

  By the way, in the present embodiment, the width L2 of the convex portion 10A in the width direction of the light detection layer 51 is at least smaller than the width L3 of the mesa portion M2 in the width direction of the convex portion 10A. Thereby, most of the spontaneous emission light having a wide divergence angle included in the light A output from the semiconductor light emitting element 40 to the semiconductor light detecting element 50 side passes through a part other than the light detecting layer 51. On the other hand, the stimulated emission light included in the light output from the semiconductor light emitting device 40 to the semiconductor light detecting device 50 side has high directivity, and most of the light is incident on the light detecting layer 51 immediately above the light emitting region 44A. To do. As a result, the amount of spontaneous emission light incident on the light detection layer 51 can be made extremely small compared to the amount of stimulated emission light incident on the light detection layer 51. Accordingly, since the spontaneous emission light can be effectively prevented from entering the light detection layer 51, the detection level of the spontaneous emission light by the semiconductor light detection element 50 can be reduced, and as a result, the stimulated emission light can be reduced. The light detection accuracy can be further improved.

  When the width L2 of the convex portion 10A in the width direction of the light detection layer 51 is (almost) equal to the width L3 of the light emitting region 44A in the width direction of the convex portion 10A, the loss of stimulated emission light is minimized. Since the limit can be set, the output level of the electric signal can be increased and the S / N can be improved.

  In the present embodiment, the structure for removing spontaneously emitted light (photodetection layer 51) is formed on the semiconductor substrate 10 having the convex portions 10A by using a crystal growth method such as MOCVD. For example, as in Patent Document 1, the shape and size of the semiconductor layer are larger than those in the case where an oxide layer that prevents transmission of spontaneous emission light is formed by oxidizing a part of the semiconductor layer using an oxidation process that is not easily controlled. Can be formed with high accuracy. Thereby, the dispersion | variation in the characteristic for every semiconductor light-emitting device can be made very small.

  Further, in order to remove spontaneously emitted light, there is no need to use a process in which volume shrinkage such as oxidation of the semiconductor layer occurs as in Patent Document 1, for example. As a result, there is no possibility of peeling due to volume shrinkage in the semiconductor photodetecting element 50, so compared with the case where a layer for removing spontaneous emission light is formed using a process in which volume shrinkage such as oxidation of the semiconductor layer is performed. Yield and reliability are extremely high.

  Further, the lower DBR layer 41 to the contact layer 52 can be collectively formed by the epitaxial crystal growth method. As a result, the manufacturing process can be simplified and the time required for manufacturing can be shortened as compared with the case where the structure for removing spontaneously emitted light is formed using another method.

[Modification of Second Embodiment]
In the above embodiment, the main light of the semiconductor light emitting element 40 is output from the semiconductor light detecting element 50 side. For example, as shown in FIGS. 21 and 22, the opening of the upper electrode 53 is blocked. Alternatively, an opening as a light emission window 39A may be provided at least in a region facing the light emitting region 44A in the lower electrode 39, and main light of the semiconductor light emitting element 40 may be emitted to the outside from the opening. However, in this case, it is necessary that the light of the semiconductor light emitting element 40 passes through the upper DBR layer 47 and slightly leaks to the semiconductor photodetector element 50 side.

  While the present invention has been described with reference to the embodiment and its modifications, the present invention is not limited to the above-described embodiment and the like, and various modifications can be made.

  For example, in the above-described embodiments and the like, the case where the semiconductor material is composed of a GaAs compound semiconductor has been described. However, other material systems such as GaInP (red) material, AlGaAs (infrared), GaN, It is also possible to configure with a system (blue green system).

  Moreover, in the said 1st Embodiment and its modification, although the processed substrate which has 10 A of convex parts on one surface was used as the semiconductor substrate 10, you may use an unprocessed flat semiconductor substrate. However, in this case, when the light detection layer is formed in a wide range including the region facing the mesa portion M1, all or a part of the light detection layer other than the region facing the mesa portion M1, particularly the semiconductor substrate. It is necessary to inactivate the portion facing the edge of 10 and the vicinity thereof so as not to exhibit the light detection function.

  In the first embodiment, the semiconductor light emitting element 20 is integrally provided on the semiconductor light detecting element 30, but for example, as shown in FIG. 23, the semiconductor light emitting element 30 is formed on the semiconductor light detecting element 30. The semiconductor light detecting element 30 may be configured separately from the semiconductor light emitting element 20 without providing the semiconductor light emitting element 20.

1 is a top view of a semiconductor light emitting device according to a first embodiment of the present invention. It is a cross-sectional block diagram of the AA arrow direction of the semiconductor light-emitting device of FIG. FIG. 6 is a top view and a cross-sectional view for explaining a manufacturing process of the semiconductor light emitting device of FIG. 1. FIG. 4 is a top view and a cross-sectional view for explaining a process following FIG. 3. FIG. 5 is a top view and a cross-sectional view for explaining a process following FIG. 4. FIG. 6 is a top view and a cross-sectional view for explaining a process following FIG. 5. FIG. 7 is a top view for explaining a process following the process in FIG. 6. It is sectional drawing of the element of FIG. FIG. 8 is a top view for explaining a process following the process in FIG. 7. FIG. 10 is a cross-sectional view of the element of FIG. 9. FIG. 10 is a top view for explaining a process following the process in FIG. 9. It is sectional drawing of the element of FIG. It is sectional drawing for demonstrating an effect | action of the semiconductor light-emitting device of FIG. FIG. 6 is a top view and a cross-sectional view of a modified example of the semiconductor substrate of FIG. 1. FIG. 10 is a top view and a cross-sectional view of another modification of the semiconductor substrate of FIG. 1. FIG. 10 is a top view and a cross-sectional view of another modification of the semiconductor substrate of FIG. 1. FIG. 10 is a top view and a cross-sectional view of still another modification of the semiconductor substrate of FIG. 1. It is a top view of the semiconductor light-emitting device concerning the 2nd Embodiment of this invention. It is a cross-sectional block diagram of the AA arrow direction of the semiconductor light-emitting device of FIG. It is sectional drawing for demonstrating an effect | action of the semiconductor light-emitting device of FIG. FIG. 19 is a top view of a modification of the semiconductor light emitting device of FIG. 18. It is sectional drawing of the AA arrow direction of the semiconductor light-emitting device of FIG. It is sectional drawing of the semiconductor photodetection element single-piece | unit of FIG.

Explanation of symbols

  DESCRIPTION OF SYMBOLS 1,2 ... Semiconductor light-emitting device, 10 ... Substrate, 20, 40 ... Semiconductor light-emitting element, 21, 41 ... Lower DBR layer, 22, 43 ... Lower spacer layer, 23, 44 ... Active layer, 23A, 44A ... Light emitting region, 24, 45 ... upper spacer layer, 25, 42 ... current confinement layer, 25A, 42A ... current confinement region, 25B, 42B ... current injection region, 26, 46 ... upper DBR layer, 27, 52 ... contact layer, 28, 53 ... Upper electrode, 28A, 47A ... Light exit window, 29, 38, 49, 54 ... Electrode pad, 30, 50 ... Semiconductor light detection element, 31 ... First conductivity type semiconductor layer, 32, 51 ... Light detection layer, 33 , 35 ... second conductivity type semiconductor layer, 34 ... current blocking layer, 36 ... common electrode, 37, 48 ... insulating film, 39 ... lower electrode.

Claims (9)

A semiconductor light emitting element and a semiconductor photodetector element are provided on one surface side of the semiconductor substrate,
The semiconductor light emitting device includes a first multilayer film reflector, an active layer including a light emitting region, and a second multilayer film reflector in order from the semiconductor substrate side, and the light emitting region is disposed on the second multilayer film reflector side. A columnar first laminated structure including a light exit window that mainly emits emitted light,
The semiconductor photodetecting element is formed integrally with the first laminated structure on the light emitting window side of the first laminated structure or on the side opposite to the light emitting window, and the first conductive semiconductor layer, the light detecting layer And a second stacked structure including a second conductivity type semiconductor layer in order from the semiconductor substrate side,
The light detection layer has a width narrower than a width of the first stacked structure in the one direction in one direction in a stacked surface of the light detection layer. 2. The semiconductor light emitting device according to claim 1, wherein the light detection layer has a width equal to or narrower than a width of the light emitting region in the one direction in the one direction. The semiconductor substrate has a convex portion on the one surface side,
The semiconductor light emitting device according to claim 1, wherein the light detection layer is formed on the convex portion. 2. The semiconductor light emitting device according to claim 1, wherein the photodetection layer has a strip-like shape extending in a direction in a stacked plane of the photodetection layer and perpendicular to the one direction. apparatus. The convex portion is formed extending in a direction parallel to the extending direction of the light detection layer,
The semiconductor light emitting device according to claim 4, wherein the light detection layer is formed by crystal growth of a semiconductor on an upper surface of the convex portion. The semiconductor light emitting device according to claim 1, wherein the light detection layer has a polygonal shape, a circular shape, or an elliptical cross-sectional shape in the in-plane direction. The convex portion has a cross-sectional shape similar to the cross-sectional shape of the photodetecting layer in the in-plane direction in the in-plane direction,
The semiconductor light emitting device according to claim 6, wherein the photodetection layer is formed by crystal growth of a semiconductor on an upper surface of the convex portion. 2. The semiconductor light emitting device according to claim 1, wherein an upper surface of the convex portion has a width narrower than a width of the first stacked structure in the one direction in the one direction. Of the first multilayer reflector and the second multilayer reflector, the reflector on the second laminated structure side, and the first laminated structure of the first conductive semiconductor layer and the second conductive semiconductor layer. The semiconductor light emitting device according to claim 1, wherein the semiconductor layer on the side contains the same conductivity type impurities.

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