Light emitting device and method for manufacturing the same

Abstract

A light-emitting device according to one embodiment of the present disclosure is provided with: a semiconductor layered body in which a first light-reflecting layer comprising an arsenic-based semiconductor layer that includes carbon as an impurity, an active layer and a second light-reflecting layer are layered; a first buffer layer that is disposed on the first light-reflecting layer side of the semiconductor layered body, and that comprises a phosphorus-based semiconductor layer with one surface that faces the semiconductor layered body and another surface on the opposite side from the one surface; and a second buffer layer that is disposed at least between the first light-reflecting layer and the first buffer layer, and that includes zinc or magnesium as an impurity.

Description

[Technical field]

[0001] FIELD OF THE DISCLOSURE The present disclosure relates to light emitting devices and methods for making light emitting devices. [Background technology]

[0002] For example, Patent Document 1 discloses a surface-emitting laser in which a protective layer made of p-type InGaP doped with zinc (Zn) as an impurity is provided on a DBR doped with carbon (C) as an impurity, thereby stabilizing laser oscillation. [Prior art documents] [Patent documents]

[0003] [Patent Document 1] JP 2000-164982 A Summary of the Invention

[0004] Meanwhile, in light emitting devices, there is a demand for improved stability of device characteristics and improved manufacturing yield.

[0005] It is desirable to provide a light emitting device and a method for manufacturing the light emitting device that can improve the stability of device characteristics and manufacturing yield.

[0006] The light emitting device according to an embodiment of the present disclosure includes: A substrate and a second light reflecting layer from the substrate side. , the active layer and a first light-reflecting layer made of an arsenic-based semiconductor layer containing carbon as an impurity; a first buffer layer formed on the first light reflecting layer side of the semiconductor laminate and made of a phosphorus-based semiconductor layer having one surface facing the semiconductor laminate and another surface opposite to the first surface; and a second buffer layer formed at least between the first light reflecting layer and the first buffer layer and made of an arsenic-based semiconductor layer containing magnesium as an impurity; The semiconductor device includes a first contact layer provided on the other surface side of the first buffer layer and made of an arsenic-based semiconductor layer containing carbon as an impurity, and a second contact layer provided between the substrate and a second light reflecting layer, the second buffer layer being provided on both one surface and the other surface of the first buffer layer, and an opening serving as a light emitting surface is formed in the first contact layer and the second buffer layer provided on the other surface side of the first buffer layer. .

[0008] One embodiment of the present disclosure The issueThe method for manufacturing an optical device includes forming a second contact layer, a second light reflecting layer, an active layer, a first light reflecting layer made of an arsenic-based semiconductor layer containing carbon as an impurity, a second buffer layer made of an arsenic-based semiconductor layer containing zinc or magnesium as an impurity, and a second light reflecting layer on a substrate. 、 A first buffer layer made of a phosphorus-based semiconductor layer a first contact layer including a second buffer layer and an arsenic-based semiconductor layer containing carbon as an impurity; After forming these in this order by crystal growth, the first buffer layer is used as an etching stop layer. Etching the first contact layer and the second buffer layer , The bottom surface light exit surface The opening becomes Form.

[0009] In the light-emitting device according to an embodiment of the present disclosure, the manufacturing method of the first light-emitting device according to an embodiment, and the manufacturing method of the second light-emitting device according to an embodiment, a second buffer layer made of an arsenic-based semiconductor layer containing zinc or magnesium as an impurity is provided between a first light-reflecting layer made of an arsenic-based semiconductor layer containing carbon as an impurity and a first buffer layer made of a phosphorus-based semiconductor layer, which constitute a semiconductor laminate. This suppresses deterioration of the surface condition of the crystal growth surface due to contact between the carbon raw material contained as an impurity in the first light-reflecting layer and the phosphorus-based semiconductor. [Brief description of the drawings]

[0010] [Figure 1] 1 is a schematic cross-sectional view illustrating an example of a configuration of a semiconductor laser according to a first embodiment of the present disclosure. [Figure 2A] 2A to 2C are schematic cross-sectional views illustrating an example of a method for manufacturing the semiconductor laser shown in FIG. [Figure 2B] FIG. 2B is a schematic cross-sectional view showing a step subsequent to FIG. 2A. [Figure 2C] FIG. 2C is a schematic cross-sectional view showing a step subsequent to FIG. 2B. [Figure 2D] FIG. 2D is a schematic cross-sectional view showing a step subsequent to FIG. 2C. [Diagram 3] 11 is a schematic cross-sectional view illustrating an example of a configuration of a semiconductor laser according to a second embodiment of the present disclosure. [Figure 4A] 4A to 4C are schematic cross-sectional views illustrating an example of a method for manufacturing the semiconductor laser shown in FIG. [Figure 4B]FIG. 4B is a schematic cross-sectional view showing a step subsequent to FIG. 4A. [Figure 4C] FIG. 4C is a schematic cross-sectional view showing a step subsequent to FIG. 4B. [Figure 4D] FIG. 4D is a schematic cross-sectional view showing a step subsequent to FIG. 4C. [Diagram 5] 2 is a block diagram illustrating an example of a schematic configuration of a distance measuring device using an illumination device equipped with the semiconductor laser shown in FIG. 1 etc. DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

[0011] Hereinafter, an embodiment of the present disclosure will be described in detail with reference to the drawings. The following description is a specific example of the present disclosure, and the present disclosure is not limited to the following embodiment. Furthermore, the present disclosure is not limited to the arrangement, dimensions, dimensional ratios, etc. of each component shown in each drawing. The order of description is as follows. 1. First embodiment (an example of a back-emitting semiconductor laser having a second buffer layer made of an arsenic-based semiconductor doped with Zn or Mg between a first reflective layer made of a C-doped arsenic-based semiconductor and a first buffer layer made of a phosphorus-based semiconductor layer) 1-1. Structure of semiconductor laser 1-2. Manufacturing method of semiconductor laser 1-3. Actions and Effects 2. Second embodiment (an example of a surface-emitting semiconductor laser having a second buffer layer made of an arsenic-based semiconductor doped with Zn or Mg between a first reflective layer made of a C-doped arsenic-based semiconductor and a first buffer layer made of a phosphorus-based semiconductor layer) 3. Application example (example of distance measuring device)

[0012] <1. First embodiment> 1 is a schematic diagram showing an example of a cross-sectional configuration of a light-emitting device (semiconductor laser 1) according to a first embodiment of the present disclosure. The semiconductor laser 1 is, for example, a back-emitting vertical cavity surface-emitting laser (VCSEL), and for example, a plurality of VCSELs are integrated in an array as a plurality of light-emitting regions.

[0013] (1-1. Structure of Semiconductor Laser) The semiconductor laser 1 has, for example, a plurality of semiconductor laminates 10 on a first surface (surface (surface 11S1)) of a substrate 11. The semiconductor laminate 10 has, for example, a columnar shape (mesa shape), and for example, a first light reflecting layer 14, an active layer 15, and a second light reflecting layer 16 are laminated in this order. A current constriction layer 17 forming a current injection region 17A is provided between the first light reflecting layer 14 and the active layer 15. This semiconductor laminate 10 corresponds to a specific example of a "semiconductor laminate" of the present disclosure. Between the semiconductor laminate 10 and the substrate 11, a first contact layer 12 and a buffer layer 13 are laminated in this order from the substrate side, and the buffer layer 13 has a multilayer structure in which, for example, a first layer 13A, a second layer 13B, and a third layer 13C are laminated in this order from the first contact layer 12 side, and forms a mesa shape together with the semiconductor laminate 10. The first contact layer 12 extends on the substrate 11 as a common layer for the plurality of semiconductor laminates 10. A first electrode 21 is provided on the first contact layer 12 as a common electrode for each semiconductor laminate 10. A second contact layer 18 and a second electrode 22 are formed in this order on the upper surface (surface 10S1) of each semiconductor laminate 10. Furthermore, the upper surface (surface 12S1) of the first contact layer 12 excluding the first electrode 21 and the second electrode 22, the upper surface of the second contact layer 18, the side surfaces of the second contact layer 18, the semiconductor laminate 10, and the buffer layer 13 are covered with an insulating film 23, and the second surface (rear surface (surface 11S2)) of the substrate 11 is covered with an insulating film 24.

[0014] The configuration and materials of each part of the semiconductor laser 1 will be described in detail below.

[0015] The substrate 11 is a support substrate on which a plurality of semiconductor laminates 10 are integrated. In the case of the back-emitting semiconductor laser 1 as in the present embodiment, it is preferable to use a semi-insulating substrate that does not contain impurities and is made of, for example, a GaAs-based semiconductor as the substrate 11. In addition, the substrate 11 may be any substrate that has a low carrier concentration and reduces absorption of laser light, and may be, for example, a substrate having a p-type or n-type carrier concentration of 5×10 17 cm -3 Substrates having the following carrier concentrations can be used:

[0016] The first contact layer 12 is made of, for example, a GaAs-based semiconductor. The first contact layer 12 serves to electrically connect the first electrode 21 and the first light reflecting layer 14 of each semiconductor laminate 10. The first contact layer 12 is made of p-type GaAs and contains, for example, carbon (C) as an impurity. The first contact layer 12 corresponds to a specific example of a "first contact layer" in the present disclosure.

[0017] As described above, the buffer layer 13 has a multilayer structure in which the first layer 13A, the second layer 13B, and the third layer 13C are stacked in this order from the first contact layer 12 side. The first layer 13A is, for example, an arsenic-based semiconductor layer containing zinc (Zn) or magnesium (Mg) as an impurity. The second layer 13B is, for example, a phosphorus-based semiconductor layer containing zinc (Zn) or magnesium (Mg) as an impurity. The third layer 13C is, like the first layer 13A, for example, an arsenic-based semiconductor layer containing zinc (Zn) or magnesium (Mg) as an impurity.

[0018] The arsenic-based semiconductor layer is a layer containing a compound semiconductor containing at least arsenic (As), and examples thereof include a GaAs layer, an AlGaAs layer, and an AlAs layer. The first layer 13A and the third layer 13C correspond to a specific example of the "second buffer layer" of the present disclosure, and can be formed as a single-layer film or a laminated film composed of any one or two or more of the above semiconductor layers. The film thickness in the stacking direction of the first layer 13A and the third layer 13C (hereinafter simply referred to as thickness) is, for example, 5 nm or more and 100 nm or less.

[0019] The phosphorus-based semiconductor layer is a layer containing a compound semiconductor containing at least phosphorus (P), and examples thereof include a GaInP layer, an AlGaInP layer, and an AlInP layer. The second layer 13B corresponds to a specific example of the "first buffer layer" of the present disclosure, and can be formed as a single-layer film or a laminated film composed of any one or two or more of the above semiconductor layers. The thickness of the second layer 13B is, for example, 50 nm or more and 300 nm or less.

[0020] The first light reflection layer 14 is disposed between the buffer layer 13 and the current constriction layer 17, and faces the second light reflection layer 16 with the active layer 15 and the current constriction layer 17 therebetween. The first light reflection layer 14 is configured to resonate the light generated in the active layer 15 with the second light reflection layer 16. The first light reflection layer 14 corresponds to a specific example of the "first light reflection layer" of the present disclosure.

[0021] The first light reflection layer 14 is a DBR (Distributed Bragg Reflector) layer in which a low refractive index layer (not shown) and a high refractive index layer (not shown) are alternately laminated. The low refractive index layer is, for example, a p-type Al x1 Ga 1-x1 As (0 < x1 ≤ 1), and the high refractive index layer is, for example, a p-type Al x2 Ga 1-x2 As (0 ≤ x2 < x1). λ is the oscillation wavelength of the laser light emitted from each light emitting region, and n is the refractive index. The first light reflection layer 14 contains, for example, carbon (C) as an impurity.

[0022] The active layer 15 is provided between the first light reflection layer 14 and the second light reflection layer 16. The active layer 15 is composed of, for example, a semiconductor material of aluminum gallium arsenide (AlGaAs) system. In the active layer 15, holes and electrons injected from the first electrode 21 and the second electrode 22 undergo radiative recombination to generate induced emission light. The region of the active layer 15 facing the current injection region 17A becomes the light emission region. In the active layer 15, for example, undoped Al x3 Ga 1-x3 As (0 < x3 ≤ 0.45) can be used. The active layer 15 may have, for example, a multiple quantum well (MQW) structure of GaAs and AlGaAs. Alternatively, the active layer 15 may be configured by a multiple quantum well structure of indium gallium arsenide (InGaAs) and AlGaAs. The active layer 15 corresponds to a specific example of the "active layer" of the present disclosure.

[0023] The second light reflection layer 16 is a DBR layer disposed between the active layer 15 and the second contact layer 18. The second light reflection layer 16 faces the first light reflection layer 14 with the active layer 15 and the current confinement layer 17 therebetween. The second light reflection layer 16 corresponds to a specific example of the "second light reflection layer" of the present disclosure.

[0024] The second light reflection layer 16 has a stacked structure in which low refractive index layers and high refractive index layers are alternately stacked. The low refractive index layer is, for example, an n-type Al with an optical film thickness of λ / 4n x4 Ga 1-x4 As (0 < x4 ≤ 1). The high refractive index layer is, for example, an n-type Al with an optical film thickness of λ / 4n x5 Ga 1-x5 As (0 ≤ x5 < x4). The second light reflection layer 16 contains, for example, silicon (Si) as an impurity.

[0025] The current confinement layer 17 is provided between the first light reflecting layer 14 and the active layer 15, and is formed, for example, in an annular shape with a predetermined width from the outer periphery side to the inside of the mesa-shaped semiconductor laminate 10. In other words, the current confinement layer 17 is provided between the first light reflecting layer 14 and the active layer 15, and has an opening of a predetermined width in its central portion, which opening serves as a current injection region 17A. The current confinement layer 17 is made of, for example, p-type AlGaAs. Specifically, the current confinement layer 17 is made of Al 0.85 Ga 0.15 It consists of As-AlAs, which is oxidized to aluminum oxide (AlO x In the semiconductor laser 1, the current injected from the first electrode 21 to the active layer 15 is confined by providing the current confinement layer 17, and the current injection efficiency is improved.

[0026] The second contact layer 18 is made of, for example, a GaAs-based semiconductor having electrical conductivity. The second contact layer 18 is made of, for example, n-type GaAs and contains, for example, silicon (Si) as an impurity. The second contact layer 18 corresponds to a specific example of a "second contact layer" in the present disclosure.

[0027] The first electrode 21 is provided on the first contact layer 12, and is formed of, for example, a multilayer film of titanium (Ti) / platinum (Pt) / gold (Au).

[0028] The second electrode 22 is provided above the semiconductor laminate 10, specifically, on the second contact layer 18, and is formed of, for example, a gold-germanium (Au--Ge) / nickel (Ni) / gold (Au) multilayer film.

[0029] The insulating film 23 is formed, for example, continuously on the upper surface of the second contact layer 18, the side surfaces of the second contact layer 18, the semiconductor laminate 10 and the buffer layer 13, and the upper surface (surface 12S1) of the first contact layer 12. The insulating film 23 is made of, for example, silicon nitride (SiN) or silicon oxide (SiO 2) or other single layer or multilayer films. An opening 23H (see, for example, FIG. 2D ) is provided on the upper surface of each second contact layer 18 of the insulating film 23 and at a predetermined position of the first contact layer 12, and a first electrode 21 or a second electrode 22 is embedded in each opening 23H.

[0030] The insulating film 24 is formed, for example, on the entire back surface (surface 11S2) of the substrate 11. The insulating film 24 is formed, for example, on silicon nitride (SiN) or silicon oxide (SiO 2 ) or other single layer or laminated film.

[0031] The semiconductor laser 1 of this embodiment is a semiconductor laser having a so-called common anode structure in which a plurality of semiconductor laminates 10 provided on a substrate 11 and a first electrode 21 are electrically connected to each other by a first contact layer 12 made of, for example, p-type GaAs.

[0032] In the semiconductor laser 1, when a predetermined voltage is applied to the first electrode 21 and the second electrode 22, a voltage is applied from the first electrode 21 to the semiconductor laminate 10 from the second electrode 22. As a result, electrons are injected from the first electrode 21 and holes are injected from the second electrode 22 into the active layer 15, and light is generated by recombination of the electrons and holes. The light is resonated and amplified between the first light reflecting layer 14 and the second light reflecting layer 16, and laser light L is emitted from the back surface (surface 11S2) of the substrate 11.

[0033] (1-2. Manufacturing method of semiconductor laser) Next, a method for manufacturing the semiconductor laser 1 will be described with reference to FIGS. 2A to 2D.

[0034] First, as shown in Fig. 2A, the compound semiconductor layers constituting the first contact layer 12, buffer layer 13, first optical reflection layer 14, active layer 15, second optical reflection layer 16 and second contact layer 18 are formed in this order on a substrate 11 by epitaxial crystal growth method such as metal organic chemical vapor deposition (MOCVD) method to fabricate an epitaxial wafer. In this case, the raw materials for arsenic-based semiconductors including GaAs-based semiconductors are methyl-based organometallic compounds such as trimethylaluminum (TMAl), trimethylgallium (TMGa) and trimethylindium (TMIn) and arsine (AsH 3 ) gas is used, and the source of the donor impurity is, for example, disilane (Si 2 H 6 ) is used, and the acceptor impurity source is, for example, carbon tetrabromide (CBr 4 The raw materials for phosphorus-based semiconductors (e.g., AlGaInP) are methyl-based organometallic compounds such as trimethylaluminum (TMAl), trimethylgallium (TMGa), and trimethylindium (TMIn), and phosphine (PH 3 ) gas is used, and the source of the donor impurity is, for example, disilane (Si 2 H 6 ) is used, and the acceptor impurity raw material is, for example, dimethyl zinc (DMZn) or cyclopentadienyl magnesium (Cp 2 Mg) is used.

[0035] Next, as shown in FIG. 2B, a resist film (not shown) of a predetermined pattern is formed on the second contact layer 18, and then the second contact layer 18, the second light reflecting layer 16, the active layer 15, and the first light reflecting layer 14 are etched using the resist film as a mask to form a columnar mesa structure (semiconductor laminate 10). At this time, it is preferable to use RIE (Reactive Ion Etching) using, for example, Cl-based gas. In the etching of the second contact layer 18, the second light reflecting layer 16, the active layer 15, and the first light reflecting layer 14, the second layer 13B of the buffer layer 13 functions as an etching stop layer. This makes the etching depth within the wafer surface constant. Then, a high-temperature treatment is performed in a water vapor atmosphere to oxidize, for example, an AlGaAs layer having a high aluminum (Al) composition that has been previously stacked during epitaxial growth, to form an oxide layer (current confinement layer 17) that confines the current.

[0036] Next, as shown in FIG. 2C, the second layer 13B and the first layer 13A of the buffer layer 13 are removed by etching to expose the first contact layer 12.

[0037] 2D, an insulating film 23 is formed on the upper surface of the second contact layer 18 so as to extend continuously from the upper surface of the second contact layer 18 to the upper surface of the first contact layer 12, and an insulating film 24 is formed on the rear surface (surface 11S2) of the substrate 11, and then a first electrode 21 and a second electrode 22 are formed on the first contact layer 12 and the second contact layer 18, respectively. The insulating films 23 and 24 are formed, for example, by a chemical vapor deposition (CVD) method or an atomic layer deposition (ALD) method. The insulating film 23 is formed so as to cover the entire upper surface (surface 12S1) of the first contact layer 12 exposed by etching from the upper surface of the second contact layer 18, and then a resist film (not shown) of a predetermined pattern is patterned on the insulating film 23, and etching such as RIE is performed to form an opening 23H at a predetermined position. Thereafter, the first electrode 21 and the second electrode 22 are patterned on the upper surface of the first contact layer 12 and the upper surface of the second contact layer 18, respectively, by using, for example, a lift-off method using a resist pattern. Through the above steps, the semiconductor laser 1 shown in FIG. 1 is completed.

[0038] (1-3. Actions and Effects) In the semiconductor laser 1 of this embodiment, a third layer 13C made of an arsenic-based semiconductor layer containing zinc (Zn) or magnesium (Mg) as an impurity is provided between a first light reflecting layer 14 made of an arsenic-based semiconductor layer containing carbon (C) as an impurity and a second layer 13B made of a phosphorus-based semiconductor layer constituting the buffer layer 13. This allows the acceptor impurity (e.g., carbon tetrabromide (CBr 4 )) and the phosphorus-based semiconductor constituting the second layer 13B, deterioration of the surface condition of the crystal growth surface due to contact therebetween. This will be described below.

[0039] As mentioned above, a surface-emitting laser has been developed in which a p-type InGaP layer doped with zinc (Zn) as an impurity is formed between the p-type DBR and an ohmic contact layer made of p-type GaAs, and this is used as an etching stop layer to stabilize laser oscillation.

[0040] In the above surface-emitting laser, both the p-type DBR and the ohmic contact layer made of p-type GaAs are doped with carbon (C) as an impurity. The MOCVD method is generally used for crystal growth of semiconductor lasers including surface-emitting lasers. When doping carbon (C) in the MOCVD method, carbon tetrabromide (CBr 4 ) and bromine chloride (BrCl 3 ) is used as a raw material. For example, carbon tetrabromide (CBr 4 When a phosphorus-based semiconductor (P-type DBR) is used, bromine (Br) is generated by thermal decomposition during crystal growth of, for example, a p-type DBR. A part of the generated bromine (Br) remains in the reactor due to the memory effect. The bromine (Br) remaining in the reactor easily reacts with the phosphorus-based semiconductor to be crystal-grown next, i.e., the InGaP layer, and may deteriorate the surface condition (e.g., flatness) of the InGaP layer and generate crystal defects and dust due to reactants on the surface of the InGaP layer, which may cause deterioration of device characteristics and a decrease in manufacturing yield.

[0041] In contrast, in the present embodiment, the third layer 13C made of an arsenic-based semiconductor layer containing zinc (Zn) or magnesium (Mg) as an impurity is provided between the first light reflecting layer 14 made of an arsenic-based semiconductor layer containing carbon (C) as an impurity and the second layer 13B made of a phosphorus-based semiconductor layer. 4 This suppresses the deterioration of the surface condition of the crystal growth surface due to contact between the C-doped material such as ZnO, ZnS, etc. and the second layer 13B made of a phosphorus-based semiconductor. Specifically, it is possible to prevent an etching reaction between the C-doped material and the phosphorus-based semiconductor layer, and to prevent the generation of defect pits on the crystal growth surface and the deterioration of surface morphology.

[0042] As described above, in the semiconductor laser 1 of this embodiment, the third layer 13C made of an arsenic-based semiconductor layer containing zinc (Zn) or magnesium (Mg) as an impurity is provided between the first light reflecting layer 14 made of an arsenic-based semiconductor layer containing carbon (C) as an impurity and the second layer 13B made of a phosphorus-based semiconductor layer, so that the deterioration of the surface condition of the crystal growth surface due to the contact between the C-doped material and the phosphorus-based semiconductor is suppressed, and an epitaxial layer with excellent flatness is formed on the phosphorus-based semiconductor layer (second layer 13B) and above it. Therefore, it is possible to improve the device characteristics and manufacturing yield of the surface-emitting laser.

[0043] In this embodiment, the first contact layer 12 is made of a GaAs-based semiconductor containing carbon (C) as an impurity, so that the first layer 13A made of an arsenic-based semiconductor layer containing zinc (Zn) or magnesium (Mg) as an impurity is provided between the first contact layer 12 and the second layer 13B made of a phosphorus-based semiconductor layer. This allows the carbon tetrabromide (CBr 4 This suppresses contact between the C-doped material, such as SiO 2 , and the second layer 13B made of a phosphorus-based semiconductor, making it possible to form the first contact layer 12 and the second layer 13B with excellent flatness.

[0044] A second embodiment and an application example of the present disclosure will be described below. In the following, the same components as those in the first embodiment are denoted by the same reference numerals, and the description thereof will be omitted as appropriate.

[0045] <2. Second embodiment> 3 is a schematic diagram showing an example of a cross-sectional configuration of a light-emitting device (semiconductor laser 2) according to a second embodiment of the present disclosure. The semiconductor laser 2 is, for example, a surface-emitting vertical cavity surface-emitting laser (VCSEL), and for example, a plurality of VCSELs are integrated in an array as a plurality of light-emitting regions.

[0046] The semiconductor laser 2 has, for example, a plurality of semiconductor laminates 10, some of which have a columnar shape (mesa shape), on the first surface (surface (surface 11S1)) of the substrate 11. In the semiconductor laminate 10 of this embodiment, for example, a second optical reflection layer 16, an active layer 15, and a first optical reflection layer 14 are laminated in this order, and a current constriction layer 17 forming a current injection region 17A is provided between the first optical reflection layer 14 and the active layer 15. A second contact layer 18 is provided between the semiconductor laminate 10 and the substrate 11, and a buffer layer 13 and a first contact layer 12 are laminated in this order on the upper surface of each semiconductor laminate 10. In the buffer layer 13, for example, a third layer 13C, a second layer 13B, and a first layer 13A are laminated in this order from the semiconductor laminate 10 side. In this embodiment, a part of the second contact layer 18 and the second optical reflection layer 16 extends on the substrate 11 as a common layer for the plurality of semiconductor laminates 10. An opening H serving as a light emission surface is formed in the first layer 13A constituting the first contact layer 12 and the buffer layer 13 above the current injection region 17A, and a first electrode 21 is provided on the first contact layer 12 around the opening H. A second electrode 22 is provided on the back surface (surface 11S2) of the substrate 11 as a common electrode for the multiple semiconductor laminates 10. Furthermore, the side and bottom surfaces of the opening H, as well as side surfaces of the first contact layer 12, the buffer layer 13, the first light reflecting layer 14, the current constriction layer 17, the active layer 15, part of the second light reflecting layer 16, and the top surface (surface 16S1) of the second light reflecting layer 16 common to each semiconductor laminate 10 are covered with a first insulating film 23.

[0047] The semiconductor laser 2 can be manufactured, for example, as follows.

[0048] First, as shown in FIG. 4A, the compound semiconductor layers constituting the second contact layer 18, the second optical reflection layer 16, the active layer 15, the first optical reflection layer 14, the buffer layer 13 and the first contact layer 12 are formed in this order on the substrate 11 by an epitaxial crystal growth method such as the MOCVD method to produce an epitaxial wafer, which is then etched down to the second optical reflection layer 16 to form a columnar mesa structure (semiconductor stack 10).

[0049] Next, as shown in FIG. 4B, a high-temperature treatment is performed in a water vapor atmosphere to oxidize a layer having a high aluminum (Al) composition, e.g., an AlGaAs layer, which has been deposited in advance during epitaxial growth, to form an oxide layer (current confinement layer 17) that confines the current.

[0050] Next, as shown in FIG. 4C, the first contact layer 12 and the first layer 13A above the current injection region 17A are selectively removed, for example by wet etching, using the second layer 13B as an etching stop layer to form an opening H whose bottom surface serves as a light emission surface.

[0051] 4D, an insulating film 23 is formed on the side and bottom of the opening H and on the upper surface of the first contact layer 12 around the opening H to the upper surface (face 16S1) of the second light reflecting layer 16, and then a first electrode 21 and a second electrode 22 are formed on the upper surface of the first contact layer 12 and the rear surface (face 11S2) of the substrate 11, respectively. The insulating film 23 is formed by, for example, a CVD method or an ALD method so as to cover the entire side and bottom of the opening H and the upper surface of the first contact layer 12 around the opening H to the upper surface (face 16S1) of the second light reflecting layer 16, and then a resist film (not shown) of a predetermined pattern is patterned, and an opening is formed on the first contact layer 12 by etching such as RIE. Thereafter, the first electrode 21 is patterned on the first contact layer 12 by, for example, a lift-off method using a resist pattern. As a result of the above, the semiconductor laser 2 shown in FIG. 3 is completed.

[0052] As described above, in the semiconductor laser 2 of the present embodiment, the third layer 13C made of an arsenic-based semiconductor layer containing zinc (Zn) or magnesium (Mg) as an impurity is provided between the first light reflecting layer 14 made of an arsenic-based semiconductor layer containing carbon (C) as an impurity, and the second layer 13B made of a phosphorus-based semiconductor layer, in which the second contact layer 18, the second light reflecting layer 16, the active layer 15, the first light reflecting layer 14, the buffer layer 13, and the first contact layer 12 are stacked in this order from the substrate 11 side. In addition, the first layer 13A having the same configuration as the third layer 13C is provided between the second layer 13B made of a phosphorus-based semiconductor layer and the first contact layer 12 made of an arsenic-based semiconductor layer containing carbon (C) as an impurity. The surface-emitting semiconductor laser 2 having such a configuration can also achieve the same effects as those of the first embodiment. That is, it is possible to improve the device characteristics and manufacturing yield of the surface-emitting laser.

[0053] In the semiconductor laser 2 of this embodiment, since the laser light L is emitted from above the semiconductor laminate 10, the substrate 11 is not limited to the semi-insulating substrate mentioned in the first embodiment, and a general gallium arsenide (GaAs) substrate may be used. Alternatively, the substrate 11 may be made of indium phosphide (InP), gallium nitride (GaN), silicon (Si), silicon carbide (SiC), or the like, depending on the material system of the light-emitting device, a bonding process of heterogeneous substrates, or the like.

[0054] <3. Application Examples> This technology can be applied to various electronic devices that contain semiconductor lasers, such as light sources provided in mobile electronic devices such as smartphones, and light sources in various sensing devices that detect shapes, movements, etc.

[0055] 5 is a block diagram showing a schematic configuration of a distance measuring device (distance measuring device 200) using the illumination device 100 equipped with the above-mentioned semiconductor laser 1. The distance measuring device 200 measures distance by the ToF method. The distance measuring device 200 has, for example, the illumination device 100, a light receiving unit 210, a control unit 220, and a distance measuring unit 230.

[0056] The lighting device 100 includes, for example, the semiconductor laser 1 shown in FIG. 1 as a light source. The lighting device 100 generates illumination light in synchronization with, for example, a rectangular wave light emission control signal CLKp. The light emission control signal CLKp is not limited to a rectangular wave as long as it is a periodic signal. For example, the light emission control signal CLKp may be a sine wave.

[0057] The light receiving unit 210 receives light reflected from the irradiation target 300, and detects the amount of light received within each period of the vertical synchronization signal VSYNC. For example, a periodic signal of 60 Hertz (Hz) is used as the vertical synchronization signal VSYNC. In addition, the light receiving unit 210 has a plurality of pixel circuits arranged in a two-dimensional lattice pattern. The light receiving unit 210 supplies image data (frames) corresponding to the amount of light received by these pixel circuits to the distance measuring unit 230. The frequency of the vertical synchronization signal VSYNC is not limited to 60 Hertz (Hz), and may be 30 Hertz (Hz) or 120 Hertz (Hz).

[0058] The control unit 220 controls the lighting device 100. The control unit 220 generates a light emission control signal CLKp and supplies it to the lighting device 100 and the light receiving unit 210. The frequency of the light emission control signal CLKp is, for example, 20 megahertz (MHz). Note that the frequency of the light emission control signal CLKp is not limited to 20 megahertz (MHz) and may be, for example, 5 megahertz (MHz).

[0059] The distance measuring unit 230 measures the distance to the irradiation object 300 based on the image data by the ToF method. This distance measuring unit 230 measures the distance for each pixel circuit and generates a depth map that indicates the distance to the object for each pixel by a gray scale value. This depth map is used, for example, in image processing that performs blurring processing according to the distance, autofocus (AF) processing that determines the focal point of the focus lens according to the distance, and the like.

[0060] Although the present technology has been described above with reference to the first and second embodiments and application examples, the present technology is not limited to the above-mentioned embodiments and can be modified in various ways. For example, the layer configuration of the semiconductor lasers 1 and 2 described in the first embodiment and the like is only an example, and other layers may be further included. In addition, the materials of each layer are also only an example, and are not limited to those described above.

[0061] For example, in the above-described first embodiment and the like, an example has been shown in which the first contact layer 12 contains carbon (C) as an impurity (dopant), but the dopant of the first contact layer 12 is not limited to carbon (C). For example, the first contact layer 12 may contain zinc (Zn) or the like as a dopant, similar to the buffer layer 13. In that case, the first layer 13A of the buffer layer 13 in contact with the first contact layer 12 may be omitted.

[0062] In the first embodiment, a back-emitting semiconductor laser (semiconductor laser 1) having an anode common structure in which the first contact layer 12, the buffer layer 13, the first light reflecting layer 14, the active layer 15, the second light reflecting layer 16, and the second contact layer 18 are stacked in this order on the substrate 11 is shown as an example, but the present invention is not limited thereto. For example, the semiconductor laser 1 may be configured as a back-emitting semiconductor laser having a so-called cathode common structure in which the second contact layer 18, the second light reflecting layer 16, the active layer 15, the first light reflecting layer 14, the buffer layer 13, and the first contact layer 12 are stacked in this order from the substrate 11 side, like the semiconductor laser 2 in the second embodiment. Similarly, the front-emitting semiconductor laser (semiconductor laser 2) described in the second embodiment may also be configured to have the first contact layer 12, the buffer layer 13, the first light reflecting layer 14, the active layer 15, the second light reflecting layer 16, and the second contact layer 18 stacked in this order from the substrate 11 side.

[0063] It should be noted that the effects described in this specification are merely examples and are not limiting, and other effects may also be present.

[0064] The present technology can be configured as follows. According to the present technology configured as follows, a second buffer layer made of an arsenic-based semiconductor layer containing zinc or magnesium as an impurity is provided between a first light reflecting layer made of an arsenic-based semiconductor layer containing carbon as an impurity and a first buffer layer made of a phosphorus-based semiconductor layer, which constitute a semiconductor laminate. This suppresses deterioration of the surface condition of the crystal growth surface caused by contact between the carbon raw material contained as an impurity in the first light reflecting layer and the phosphorus-based semiconductor, making it possible to improve the stability of device characteristics and manufacturing yield. (1) A substrate; A second light reflecting layer from the substrate side , the active layer and a first light-reflecting layer made of an arsenic-based semiconductor layer containing carbon as an impurity; A stacked semiconductor laminate; a first buffer layer formed on the first light reflecting layer side of the semiconductor laminate and made of a phosphorus-based semiconductor layer having one surface facing the semiconductor laminate and another surface opposite to the one surface; a second buffer layer provided at least between the first light reflecting layer and the first buffer layer and made of an arsenic-based semiconductor layer containing magnesium as an impurity; a first contact layer provided on the other surface side of the first buffer layer and made of an arsenic-based semiconductor layer containing carbon as an impurity; a second contact layer provided between the substrate and the second light reflecting layer; the second buffer layer is provided on both the one surface and the other surface of the first buffer layer; An opening serving as a light emitting surface is formed in the first contact layer and the second buffer layer provided on the other surface side of the first buffer layer. Light emitting device. (2) The light-emitting device according to (1) above, wherein the arsenic-based semiconductor layer is a single layer or a multilayer film made of one or more layers selected from the group consisting of a GaAs layer, an AlGaAs layer, and an AlAs layer. (3) The light-emitting device according to (1) or (2), wherein the phosphorus-based semiconductor layer is a single layer or a multilayer film made of one or more layers selected from the group consisting of a GaInP layer, an AlGaInP layer, and an AlInP layer. (4 ) before The semiconductor laminate further includes a current confinement layer having a current injection region between the first light reflecting layer and the active layer. Any one of (1) to (3) aboveThe light emitting device according to claim 1 . (5) The semiconductor laminate further includes a first electrode and a second electrode that are provided so as to be able to apply a predetermined voltage to the semiconductor laminate. Any one of (1) to (4) above The light emitting device according to claim 1 . (6) The semiconductor stack emits laser light above the semiconductor stack. Any one of (1) to (5) above The light emitting device according to claim 1 . (7) A second contact layer, a second light reflecting layer, an active layer, a first light reflecting layer made of an arsenic-based semiconductor layer containing carbon as an impurity, and a second buffer layer made of an arsenic-based semiconductor layer containing zinc or magnesium as an impurity, are disposed on a substrate. 、 A first buffer layer made of a phosphorus-based semiconductor layer a first contact layer comprising the second buffer layer and an arsenic-based semiconductor layer containing carbon as an impurity; are formed in this order by crystal growth, The first buffer layer is used as an etching stop layer. Etching the first contact layer and the second buffer layer , The bottom surface light exit surface The opening becomes Form A method for manufacturing a light-emitting device. (8) forming the first buffer layer, the second buffer layer, the first light-reflecting layer, the active layer and the second light-reflecting layer successively by metal-organic chemical vapor deposition; (7) A method for producing the light-emitting device according to claim 1.

[0065] This application claims priority based on Japanese Patent Application No. 2020-025190, filed on February 18, 2020 in the Japan Patent Office, the entire contents of which are incorporated herein by reference.

[0066] Those skilled in the art will recognize that various modifications, combinations, subcombinations, and variations may occur to those skilled in the art depending on design requirements and other factors, and that such modifications are within the scope of the appended claims and their equivalents.

Claims

1. A substrate, a semiconductor laminate including a second light reflecting layer, an active layer, and a first light reflecting layer including an arsenic-based semiconductor layer containing carbon as an impurity, laminated in this order from the substrate side; a first buffer layer formed on the first light reflecting layer side of the semiconductor laminate and made of a phosphorus-based semiconductor layer having one surface facing the semiconductor laminate and another surface opposite to the one surface; a second buffer layer provided at least between the first light reflecting layer and the first buffer layer and made of an arsenic-based semiconductor layer containing magnesium as an impurity; a first contact layer provided on the other surface side of the first buffer layer and made of an arsenic-based semiconductor layer containing carbon as an impurity; a second contact layer provided between the substrate and the second light reflecting layer; the second buffer layer is provided on both the one surface and the other surface of the first buffer layer; An opening serving as a light emitting surface is formed in the first contact layer and the second buffer layer provided on the other surface side of the first buffer layer. Light emitting device.

2. 2. The light-emitting device according to claim 1, wherein the arsenic-based semiconductor layer is a single layer or a multilayer film made of one or more layers selected from the group consisting of a GaAs layer, an AlGaAs layer, and an AlAs layer.

3. 2. The light-emitting device according to claim 1, wherein the phosphorus-based semiconductor layer is a single layer or a multilayer film made of one or more layers selected from the group consisting of a GaInP layer, an AlGaInP layer, and an AlInP layer.

4. The light-emitting device according to claim 1 , wherein the semiconductor stack further comprises a current confinement layer having a current injection region between the first light reflecting layer and the active layer.

5. The light-emitting device according to claim 1 , further comprising a first electrode and a second electrode provided so as to be able to apply a predetermined voltage to the semiconductor laminate.

6. The light emitting device according to claim 1 , wherein the semiconductor stack emits laser light upward.

7. a second contact layer, a second light reflecting layer, an active layer, a first light reflecting layer made of an arsenic-based semiconductor layer containing carbon as an impurity, a second buffer layer made of an arsenic-based semiconductor layer containing zinc or magnesium as an impurity, a first buffer layer made of a phosphorus-based semiconductor layer, the second buffer layer, and a first contact layer made of an arsenic-based semiconductor layer containing carbon as an impurity are formed in this order on a substrate by crystal growth; The first contact layer and the second buffer layer are etched using the first buffer layer as an etching stop layer to form an opening whose bottom surface serves as a light emitting surface. A method for manufacturing a light-emitting device.

8. 8. The method for producing a light-emitting device according to claim 7, wherein the first buffer layer, the second buffer layer, the first light-reflecting layer, the active layer and the second light-reflecting layer are successively formed by metal-organic chemical vapor deposition.

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