Surface-emitting laser

Abstract

The present technology provides a surface-emitting laser with which it is possible to reduce voltage drop at a tunnel junction.　The present technology provides a surface-emitting laser comprising: first and second multilayer mirrors (102, 112) stacked upon one another; a plurality of active layers stacked upon one another between the first and second multilayer mirrors (102, 112); and a tunnel junction (107) disposed between first and second active layers (104, 110) adjacent to each other in a stacking direction among the plurality of active layers. The tunnel junction (107) includes an n-type semiconductor layer (107b) and a p-type semiconductor layer (107a) stacked upon one another. The p-type semiconductor layer (107a) includes first and second p-type semiconductor regions (107a1, 107a2) stacked upon one another.

Description

[Technical Field]

[0001] The technology disclosed herein (hereinafter also referred to as "this technology") relates to a surface-emitting laser. [Background technology]

[0002] Conventionally, surface-emitting lasers are known in which multiple active layers are stacked on top of each other between a first and a second multilayer reflecting mirror. Some of these surface-emitting lasers have tunnel junctions between two adjacent active layers in the stacking direction (see, for example, Patent Document 1). [Prior art documents] [Patent Documents]

[0003] [Patent Document 1] Japanese Patent Publication No. 2006-351798 [Overview of the project] [Problems that the invention aims to solve]

[0004] However, conventional surface-emitting lasers had room for improvement in reducing voltage drops at tunnel junctions.

[0005] Therefore, the primary objective of this technology is to provide a surface-emitting laser that can reduce voltage drop at tunnel junctions. [Means for solving the problem]

[0006] This technology uses first and second multilayer reflecting mirrors, A plurality of active layers stacked on top of each other between the first and second multilayer reflecting mirrors, A tunnel junction is disposed between the first and second active layers, which are adjacent to each other in the stacking direction, among the plurality of active layers. Equipped with, The aforementioned tunnel junction is, It includes an n-type semiconductor layer and a p-type semiconductor layer stacked on top of each other, The p-type semiconductor layer includes first and second p-type semiconductor regions stacked on each other, and provides a surface-emitting laser. The first p-type semiconductor region may be disposed between the n-type semiconductor layer and the second p-type semiconductor region. The first p-type semiconductor region may be in contact with the n-type semiconductor layer. The second p-type semiconductor region may be in contact with the first p-type semiconductor region. The carrier concentrations of the first p-type semiconductor region and the second p-type semiconductor region may be different from each other. The band gaps of the first p-type semiconductor region and the second p-type semiconductor region may be different from each other. The carrier concentration of the second p-type semiconductor region may be higher than the carrier concentration of the first p-type semiconductor region. The band gap of the first p-type semiconductor region may be smaller than the band gap of the second p-type semiconductor region. The surface-emitting laser may further include a composition gradient layer disposed between the first active layer and the tunnel junction and / or between the second active layer and the tunnel junction. The surface-emitting laser may further include a spacer layer disposed between the active layer having the composition gradient layer disposed therebetween and the tunnel junction among the first and second active layers. The plurality of active layers are at least three active layers including the first and second active layers, and the tunnel junction is disposed between each pair of adjacent two active layers among the plurality of active layers, and a composition gradient layer may be disposed between at least one of the plurality of tunnel junctions and at least one of the adjacent two active layers sandwiching the one tunnel junction. The first p-type semiconductor region may be made of a GaAs compound semiconductor, an AlGaAs-based compound semiconductor, or an InGaAs-based compound semiconductor. The second p-type semiconductor region may be made of a GaAs compound semiconductor, an AlGaInAs-based compound semiconductor, or an AlGaAs-based compound semiconductor. The Al compositions of the first p-type semiconductor region and the second p-type semiconductor region may be different from each other. The Al composition of the second p-type semiconductor region may be larger than the Al composition of the first p-type semiconductor region. The first p-type semiconductor region and / or the second p-type semiconductor region may be doped with at least one of C, Zn, Mg, and Be.

Brief Description of the Drawings

[0007] [Figure 1] It is a cross-sectional view showing the configuration of a surface-emitting laser according to the first embodiment of the present technology. [Figure 2] It is a flowchart for explaining a method of manufacturing a surface-emitting laser according to the first embodiment of the present technology. [Figure 3] It is a flowchart for explaining the first step (laminated body generation process 1) in FIG. 2. [Figure 4] It is a first lamination process diagram of the laminated body generation process 1. [Figure 5] It is a second lamination process diagram of the laminated body generation process 1. [Figure 6] It is a third lamination process diagram of the laminated body generation process 1. [Figure 7] It is a fourth lamination process diagram of the laminated body generation process 1. [Figure 8] It is a fifth lamination process diagram of the laminated body generation process 1. [[ID=�5]] [Figure 9] It is a sixth lamination process diagram of the laminated body generation process 1. [Figure 10] It is a seventh lamination process diagram of the laminated body generation process 1. [Figure 11] It is an eighth lamination process diagram of the laminated body generation process 1. [Figure 12] It is a ninth lamination process diagram of the laminated body generation process 1. [Figure 13] It is a second step diagram in FIG. 2. [Figure 14] It is a third step diagram in FIG, 2. [Figure 15] It is a fourth step diagram in FIG. 2. [Figure 16]This is the fifth step diagram in Figure 2. [Figure 17] This is the sixth step diagram in Figure 2. [Figure 18] This is the seventh step diagram in Figure 2. [Figure 19] This is a cross-sectional view showing the configuration of a surface-emitting laser according to a modified example 1 of the first embodiment of this technology. [Figure 20] This is a cross-sectional view showing the configuration of a surface-emitting laser according to a modified example 2 of the first embodiment of this technology. [Figure 21] This is a cross-sectional view showing the configuration of a surface-emitting laser according to a modified example 3 of the first embodiment of this technology. [Figure 22] This is a cross-sectional view showing the configuration of a surface-emitting laser according to a modified example 4 of the first embodiment of this technology. [Figure 23] This is a cross-sectional view showing the configuration of a surface-emitting laser according to a modified example 5 of the first embodiment of this technology. [Figure 24] This is a cross-sectional view showing the configuration of a surface-emitting laser according to a modified example 6 of the first embodiment of this technology. [Figure 25] This is a cross-sectional view showing the configuration of a surface-emitting laser according to a modified example 7 of the first embodiment of this technology. [Figure 26] This is a cross-sectional view showing the configuration of a surface-emitting laser according to a modified example 8 of the first embodiment of this technology. [Figure 27] This is a cross-sectional view showing the configuration of a surface-emitting laser according to the second embodiment of this technology. [Figure 28] This is a flowchart illustrating the manufacturing method of a surface-emitting laser according to the second embodiment of this technology. [Figure 29] This is a flowchart illustrating the first step (Laminate Formation Process 2) shown in Figure 28. [Figure 30] This is a diagram of the fourth layering process of the laminate formation process 2. [Figure 31] This is a diagram of the fifth layering process in the laminate formation process 2. [Figure 32] This is a diagram of the sixth layering process of the laminate formation process 2. [Figure 33] This is a diagram of the 7th layering process of the laminate formation process 2. [Figure 34]This is a diagram of the 8th layering process of the laminate formation process 2. [Figure 35] Figure 28 is the second process diagram. [Figure 36] This is the third process diagram in Figure 28. [Figure 37] This is the fourth process diagram in Figure 28. [Figure 38] This is the fifth step diagram in Figure 28. [Figure 39] This is the sixth process diagram in Figure 28. [Figure 40] This is the seventh step diagram in Figure 28. [Figure 41] This is a cross-sectional view showing the configuration of a surface-emitting laser according to a modified example 1 of the second embodiment of this technology. [Figure 42] This is a cross-sectional view showing the configuration of a surface-emitting laser according to a modified example 2 of the second embodiment of this technology. [Figure 43] This is a cross-sectional view showing the configuration of a surface-emitting laser according to a modified example 3 of the second embodiment of this technology. [Figure 44] This is a cross-sectional view showing the configuration of a surface-emitting laser according to a modified example 4 of the second embodiment of this technology. [Figure 45] This is a cross-sectional view showing the configuration of a surface-emitting laser according to a modified example 5 of the second embodiment of this technology. [Figure 46] This is a cross-sectional view showing the configuration of a surface-emitting laser according to a modified example 6 of the second embodiment of this technology. [Figure 47] This is a cross-sectional view showing the configuration of a surface-emitting laser according to a modified example 7 of the second embodiment of this technology. [Figure 48] This is a cross-sectional view showing the configuration of a surface-emitting laser according to a modified example 8 of the second embodiment of this technology. [Figure 49] This is a cross-sectional view showing the configuration of a surface-emitting laser according to a modified example 9 of the second embodiment of this technology. [Figure 50] This is a cross-sectional view showing the configuration of a surface-emitting laser according to a modified example 10 of the second embodiment of this technology. [Figure 51] This is a cross-sectional view showing the configuration of a surface-emitting laser according to a modified example 11 of the second embodiment of this technology. [Figure 52]This is a cross-sectional view showing the configuration of a surface-emitting laser according to a modified example 12 of the second embodiment of this technology. [Figure 53] This is a cross-sectional view showing the configuration of a surface-emitting laser according to a modified example 13 of the second embodiment of this technology. [Figure 54] This is a cross-sectional view showing the configuration of a surface-emitting laser according to a modified example 14 of the second embodiment of this technology. [Figure 55] This is a plan view showing an example configuration of a surface-emitting laser to which this technology can be applied. [Figure 56] Figure 56A is a cross-sectional view taken along line XX in Figure 55. Figure 56B is a cross-sectional view taken along line YY in Figure 55. [Figure 57] This figure shows examples of the application of each embodiment of this technology and its modifications to a distance measuring device using a surface-emitting laser. [Figure 58] This block diagram shows an example of a schematic configuration of a vehicle control system. [Figure 59] This is an explanatory diagram showing an example of the installation location of a distance measuring device. [Modes for carrying out the invention]

[0008] Preferred embodiments of the present technology will be described in detail below with reference to the attached drawings. In this specification and the drawings, components having substantially the same functional configuration are denoted by the same reference numerals, and redundant explanations will be omitted. The embodiments described below represent typical embodiments of the present technology and should not be interpreted as narrowing the scope of the present technology. Even if this specification describes that the surface-emitting laser according to the present technology has multiple effects, it is sufficient for the surface-emitting laser according to the present technology to have at least one effect. The effects described in this specification are merely examples and are not limiting, and other effects may also be present.

[0009] Furthermore, the explanation will be given in the following order. 1. Surface-emitting laser according to the first embodiment of this technology (1) Configuration of a surface-emitting laser (2) Operation of surface-emitting laser (3) Method for manufacturing a surface-emitting laser (4) Effects of surface-emitting lasers 2. Surface-emitting lasers according to modified examples 1 to 8 of the first embodiment of this technology 3. Surface-emitting laser according to the second embodiment of this technology (1) Configuration of a surface-emitting laser (2) Operation of surface-emitting laser (3) Method for manufacturing a surface-emitting laser (4) Effects of surface-emitting lasers 4. Surface-emitting lasers according to modified examples 1 to 14 of the second embodiment of this technology 5. Example configuration of a surface-emitting laser to which this technology can be applied 6. Variations of this technology 7. Examples of applications in electronic devices 8. Example of applying a surface-emitting laser to a distance measuring device 9. Example of mounting a distance measuring device on a mobile device

[0010] 1. Surface-emitting laser according to the first embodiment of this technology (1) Configuration of a surface-emitting laser Figure 1 is a cross-sectional view showing the configuration of a surface-emitting laser 100 according to the first embodiment of this technology. For convenience, in the following description, the upper part of the cross-sectional view in Figure 1 and other images will be referred to as "up" and the lower part as "down".

[0011] As an example, the surface-emitting laser 100 includes first and second multilayer reflectors 102, 112, a plurality (e.g., two) of active layers 104, 110, and a tunnel junction 107, as shown in Figure 1.

[0012] Each component of the surface-emitting laser 100 is formed on a substrate 101 (semiconductor substrate), for example.

[0013] The first and second multilayer reflectors 102 and 112 are stacked on a substrate 101, for example. Here, the second multilayer reflector 112 is positioned above the first multilayer reflector 102. Multiple (e.g., two) active layers 104 and 110 are stacked on top of each other between the first and second multilayer reflectors 102 and 112. The tunnel junction 107 is positioned between the first and second active layers 104 and 110 that are adjacent in the stacking direction (vertical direction). In the surface-emitting laser 100, as an example, a first multilayer reflector 102, a first active layer 104, a tunnel junction 107, a second active layer 110, and a second multilayer reflector 112 are stacked on the substrate 101 in this order from the substrate 101 side.

[0014] Here, the resonator is composed of the first and second active layers 104 and 110 and the tunnel junction 107. Furthermore, the resonator structure is composed of the first multilayer reflector 102, the resonator, and the second multilayer reflector 112.

[0015] On the substrate 101, a mesa M1 is formed, for example, including a part (upper part) of the first multilayer reflector 102, the first and second active layers 104 and 110, the tunnel junction 107, and the second multilayer reflector 112. The mesa M1 constitutes a resonator structure (excluding the other part (lower part) of the first multilayer reflector 102). The mesa M1 is, for example, approximately cylindrical in shape, but may also have other columnar shapes such as approximately elliptical or polygonal. The height direction of the mesa M1 is approximately the same as the stacking direction.

[0016] For example, the surface-emitting laser 100 emits light from the top of the mesa M1. In other words, the surface-emitting laser 100 is, for example, a surface-emitting type surface-emitting laser.

[0017] The surface-emitting laser 100 further has a first composition gradient layer 106 between the tunnel junction 107 and the first active layer 104, and a second composition gradient layer 108 between the tunnel junction 107 and the second active layer 110.

[0018] The surface-emitting laser 100 further includes a first active layer 104, which is an active layer among the first and second active layers 104 and 110, with a first composition gradient layer 106 disposed between it and the tunnel junction 107, and a first spacer layer 105 disposed between the first composition gradient layer 106.

[0019] The surface-emitting laser 100 further includes a second active layer 110, which is an active layer among the first and second active layers 104 and 110, with a second composition gradient layer 108 disposed between it and the tunnel junction 107, and a second spacer layer 109 disposed between the second composition gradient layer 108.

[0020] [substrate] The substrate 101 is, for example, a first-conductivity type (e.g., n-type) semiconductor substrate (e.g., a GaAs substrate). A cathode electrode 117, which is the n-side electrode, is provided on the back surface (bottom surface) of the substrate 101.

[0021] The cathode electrode 117 is made of AuGe / Ni / Au as an example.

[0022] [First multilayer reflector] The first multilayer reflecting mirror 102 is, for example, placed on the substrate 101. The first multilayer reflector 102 is, for example, a semiconductor multilayer reflector. Multilayer reflectors are also called distributed Bragg reflectors. Semiconductor multilayer reflectors, a type of multilayer reflector (distributed Bragg reflector), have low light absorption, high reflectivity, and conductivity. More specifically, the first multilayer mirror 102 is, for example, a semiconductor multilayer mirror of the first conductivity type (e.g., n-type), and has a structure in which multiple types (e.g., two types) of semiconductor layers with different refractive indices are alternately stacked with an optical thickness of 1 / 4 wavelength of the oscillation wavelength. Each refractive index layer of the first multilayer mirror 102 is made of an AlGaAs-based compound semiconductor of the first conductivity type (e.g., n-type).

[0023] [1st active layer] The first active layer 104 is, for example, a first cladding layer 103 made of an undoped AlGaAs-based compound semiconductor (for example, Al with a film thickness of 30 nm). 0.40 It is placed on the first multilayer reflecting mirror 102 via a GaAs layer. The first active layer 104 is, for example, an undoped InGaAs-based compound semiconductor (e.g., In 0.10 An active region consisting of GaAs and an undoped AlGaAs-based compound semiconductor (e.g., AlGaAs) 0.10 The material has a laminated structure in which guide and barrier regions made of GaAs are alternately stacked (where both ends in the stacking direction are guide regions and the middle is a barrier region). Here, the first active layer 104, as an example, has two guide regions, two barrier regions, and three active regions, with both ends in the stacking direction being guide regions. The thickness of each active region is, for example, 7 nm. The thickness of the guide regions at both ends in the stacking direction is, for example, 10 nm. The thickness of the barrier region in the middle of the stacking direction is, for example, 8 nm. The first active layer 104, having this stacked structure, is capable of performing laser oscillation with an oscillation wavelength of, for example, 900 nm.

[0024] [First composition gradient layer] The first composition gradient layer 106 is, for example, a first spacer layer 105 made of an undoped AlGaAs-based compound semiconductor (for example, Al with a thickness of 14 nm). 0.40 It is located on the first active layer 104 via a GaAs layer. The first composition gradient layer 106 is composed of a semiconductor layer of the second conductivity type (e.g., p-type) with a relatively high carrier concentration. As the first composition gradient layer 106, for example, C (carbon) is present in a relatively high concentration (e.g., 6 x 10⁻¹⁶). 17 cm -3 AlGaAs-based compound semiconductors doped with ) can be used. The first composition gradient layer 106 has an Al composition that decreases continuously (gradually) or stepwise (discontinuously) from the first active layer 104 side to the tunnel junction 107 side. The first composition gradient layer 106 has an Al composition that changes continuously or stepwise, for example, in the range of 0.05 to 0.40. The thickness of the first composition gradient layer 106 can be, for example, 10 nm. As an example where the Al composition of the first composition gradient layer 106 changes stepwise, from the first active layer 104 side to the tunnel junction 107 side, it may have an AlGaAs layer with a thickness of 3 nm, an AlGaAs layer with a thickness of 4 nm, and an AlGaAs layer with a thickness of 3 nm in this order. 0.35 GaAs layer, an Al 0.20 GaAs layer and an Al 0.05 GaAs layer.

[0025] [Tunnel Junction] The tunnel junction 107 is, for example, disposed on the first composition gradient layer 106. The tunnel junction 107 includes a p-type semiconductor layer 107a and an n-type semiconductor layer 107b stacked on each other. The p-type semiconductor layer 107a is, for example, disposed on the substrate 101 side (lower side) of the n-type semiconductor layer 107b.

[0026] (n-type semiconductor layer) The n-type semiconductor layer 107b is, for example, made of an n-type InGaAs-based compound semiconductor with a high carrier concentration. As the n-type semiconductor layer 107b, for example, an InGaAs layer with a thickness of 20 nm doped with Si (silicon) at a high concentration (e.g., 5x10 19 cm -3 ) can be used. The InGaAs-based compound semiconductor has a smaller bandgap than, for example, an AlGaAs-based compound semiconductor. 0.10 GaAs layer.

[0027] (p-type semiconductor layer) The p-type semiconductor layer 107a includes first and second p-type semiconductor regions 107a1 and 107a2 stacked on each other. The first p-type semiconductor region 107a1 is disposed between the n-type semiconductor layer 107b and the second p-type semiconductor region 107a2. Here, as an example, the second p-type semiconductor region 107a2 is disposed on the substrate 101 side (lower side) of the first p-type semiconductor region 107a1.

[0028] For example, the first p-type semiconductor region 107a1 is in contact with the n-type semiconductor layer 107b. For example, the second p-type semiconductor region 107a2 is in contact with the first p-type semiconductor region 107a1.

[0029] In order to reduce voltage drop in a tunnel junction (to achieve low resistance), it is desirable that the band gap of the region in the p-type semiconductor layer of the tunnel junction that is in contact with the n-type semiconductor layer (the region that forms a pn junction with the n-type semiconductor layer) be small. For example, it is preferable that the band gap of the first p-type semiconductor region 107a1 is smaller than the band gap of the second p-type semiconductor region 107a2. Furthermore, it is desirable that the region of the p-type semiconductor layer in the tunnel junction that is in contact with the n-type semiconductor layer has a high carrier concentration (doping concentration). However, it is difficult to increase carrier concentration while maintaining a small band gap. Therefore, when using a material with a small band gap in the region of the p-type semiconductor layer of a tunnel junction that is in contact with the n-type semiconductor layer, it is desirable to increase the carrier concentration in the other regions. Specifically, as in this technology, it is effective to construct the material from multiple p-type semiconductor regions stacked on top of each other. This is because it is possible to give each of the multiple p-type semiconductor regions different properties. More specifically, when a material with a small band gap is used in the first p-type semiconductor region 107a1, it is preferable to use a material with a high carrier concentration in the second p-type semiconductor region 107a2. For example, it is preferable that the carrier concentration in the second p-type semiconductor region 107a2 is higher than that in the first p-type semiconductor region 107a1. For example, it is preferable that the Al composition of the second p-type semiconductor region 107a2 is greater than that of the first p-type semiconductor region 107a1. This is because a larger Al composition allows for a higher carrier concentration.

[0030] Incidentally, when using an AlGaAs-based compound semiconductor or an InGaAs-based compound semiconductor containing GaAs in the p-type semiconductor layer, for example, a higher Al composition allows for higher doping, but conversely, it results in a larger band gap. Therefore, it is preferable to select the material to be used for each p-type semiconductor region while taking this trade-off relationship into consideration.

[0031] The first p-type semiconductor region 107a1 is, for example, a p-type GaAs compound semiconductor, AlGaAs-based compound semiconductor, or InGaAs-based compound semiconductor with a high carrier concentration. Preferably, the first p-type semiconductor region 107a1 is doped with at least one of C, Zn, Mg, and Be. For example, the first p-type semiconductor region 107a1 may have a high concentration of C (carbon) (e.g., 1 x 10⁻¹⁶). 20 cm -3 A GaAs layer, for example, 5 nm thick, doped in ) can be used. The GaAs layer has a smaller band gap than the AlGaAs layer.

[0032] The second p-type semiconductor region 107a2 is, for example, in contact with the first composition gradient layer 106. The second p-type semiconductor region 107a2 is, for example, a p-type GaAs compound semiconductor, AlGaInAs-based compound semiconductor, or AlGaAs-based compound semiconductor with a high carrier concentration. It is preferable that the second p-type semiconductor region 107a2 is doped with at least one of C, Zn, Mg, and Be. For example, the second p-type semiconductor region 107a2 may have a high concentration of C (e.g., 3 x 10⁻¹⁰). 20 cm -3 For example, Al doped with a thickness of 5 nm 0.05 A GaAs layer can be used.

[0033] [Second composition gradient layer] As an example, the second composition gradient layer 108 is located above the tunnel junction 107. The second composition gradient layer 108 is composed of a semiconductor layer of the first conductivity type (e.g., n-type) with a relatively high carrier concentration. -3Examples include AlGaAs-based compound semiconductors doped with ). The Al composition of the second composition gradient layer 108 decreases continuously (gradually) or stepwise (discontinuously) from the second active layer 110 side to the tunnel junction 107 side. The second composition gradient layer 108 has an Al composition that changes continuously or stepwise, for example, in the range of 0.05 to 0.40. The total film thickness of the second composition gradient layer 108 can be, for example, 10 nm. The second composition gradient layer 108 is an example of a stepwise change in Al composition, with a film thickness of 3 nm Al from the second active layer 110 side to the tunnel junction 107 side. 0.35 GaAs layer, Al thickness 4nm 0.20 GaAs layer and Al film thickness of 3 nm 0.05 The GaAs layers may be arranged in this order.

[0034] [Second active layer] The second active layer 110 is, for example, a second spacer layer 108 made of an undoped AlGaAs-based compound semiconductor (for example, Al with a film thickness of 14 nm). 0.40 It is placed on the second composition gradient layer 108 via a GaAs film. The second active layer 110 has, for example, a layer structure similar to that of the first active layer 104. That is, the second active layer 110 has, for example, an undoped InGaAs-based compound semiconductor (e.g., In 0.10 An active region consisting of GaAs and an undoped AlGaAs-based compound semiconductor (e.g., AlGaAs) 0.10 The material has a laminated structure in which guide and barrier regions made of GaAs are alternately stacked (where both ends in the stacking direction are guide regions and the middle is a barrier region). In this case, the second active layer 110 has, for example, two guide regions, two barrier regions, and three active regions, with both ends in the stacking direction being guide regions. The film thickness of each active region is, for example, 7 nm. The film thickness of the guide regions at both ends in the stacking direction is, for example, 10 nm. The film thickness of the barrier region in the middle of the stacking direction is, for example, 8 nm. The second active layer 110, having this stacked structure, is capable of performing laser oscillation with an oscillation wavelength of, for example, 900 nm.

[0035] [Second multilayer reflector] The second multilayer reflecting mirror 112 is, for example, a second cladding layer 111 made of an undoped AlGaAs-based compound semiconductor (for example, Al with a film thickness of 30 nm). 0.40 It is located on the second active layer 110 via a GaAs layer. The second multilayer reflector 112 is, for example, a semiconductor multilayer reflector. Multilayer reflectors are also called distributed Bragg reflectors. Semiconductor multilayer reflectors, a type of multilayer reflector (distributed Bragg reflector), have low light absorption, high reflectivity, and conductivity. More specifically, the second multilayer mirror 112 is, for example, a second conductivity type (e.g., p-type) semiconductor multilayer mirror, and has a structure in which multiple types (e.g., two types) of semiconductor layers with different refractive indices are alternately stacked with an optical thickness of 1 / 4 wavelength of the oscillation wavelength. Each refractive index layer of the second multilayer mirror 112 is made of a second conductivity type (e.g., p-type) AlGaAs-based compound semiconductor.

[0036] A current-constricting layer 113 (oxidation-constricting layer) is arranged inside the second multilayer mirror 112. The current-constricting layer 113 has, for example, a non-oxidation region 113a made of a second conductivity type (e.g., n-type) AlGaAs-based compound semiconductor (e.g., AlGaAs, AlAs, etc.) and an oxidation region 113b surrounding it, made of an oxide of the AlGaAs-based compound semiconductor (e.g., Al2O3). It is preferable to use an AlGaAs film with an Al composition of 90% or more as the substrate for the current-constricting layer 113 (selectable oxidation layer 113S, described later).

[0037] A contact layer 114 made of a GaAs layer of the second conductivity type (e.g., p-type) is placed on the second multilayer reflecting mirror 112.

[0038] Mesa M1 is covered with an insulating film 115, with some exceptions. The insulating film 115 is made of a dielectric material such as SiO2, SiN, or SiON. A contact hole 115a is formed in the insulating film 115 on the top of the mesa M1 (for example, the upper surface of the contact layer 114), and an annular anode electrode 116, which is the p-side electrode, is provided within the contact hole 115a so as to be in contact with the top of the mesa M1. As an example, the anode electrode 116 is positioned within the contact hole 115a such that its center, when viewed from the stacking direction, substantially coincides with the center of the current constriction layer 113. The inner diameter side of the anode electrode 116 serves as the laser beam exit port. The anode electrode 116 is made of Ti / Pt / Au as an example.

[0039] (2) Operation of surface-emitting laser In the surface-emitting laser 100, when a voltage is applied between the anode electrode 116 and the cathode electrode 117 and a current flows into the anode electrode 116, this current is narrowed by the current-constricting layer 113 and injected into the second active layer 110, and simultaneously, due to the tunneling effect by the tunnel junction 107, a current with approximately the same value as the injected current is injected into the first active layer 104. As a result, the first and second active layers 104 and 110 emit light with approximately the same emission intensity, and when the light from these layers travels back and forth between the first and second multilayer reflectors 102 and 112, amplified by each active layer, and the oscillation conditions are met, the light is emitted as laser light from the top of the mesa M1.

[0040] (3) Method for manufacturing a surface-emitting laser The manufacturing method for the surface-emitting laser 100 will be described below with reference to the flowchart (steps S1 to S7) in Figure 2. Here, as an example, multiple surface-emitting laser arrays, in which multiple surface-emitting lasers 100 are arranged in two dimensions, are simultaneously generated on a single wafer, which is the substrate 101, using a semiconductor manufacturing method with semiconductor manufacturing equipment. Next, the series of integrated surface-emitting laser arrays are separated from each other to obtain multiple chip-shaped surface-emitting laser arrays (surface-emitting laser array chips). It should be noted that, using the manufacturing method described below, it is also possible to simultaneously generate multiple surface-emitting lasers 100 on a single wafer, which is the substrate 101, and separate the series of integrated surface-emitting lasers 100 from each other to obtain chip-shaped surface-emitting lasers (surface-emitting laser chips).

[0041] <Step S1> In step S1, the laminate formation process 1 is performed. In the laminate formation process 1, as an example, the materials for each layer constituting the surface-emitting laser 100 are sequentially stacked in a growth chamber using a chemical vapor deposition (CVD) method, such as a metal-organic vapor deposition (MOCVD) method, to produce a laminate L1 (see Figure 12).

[0042] The laminate formation process 1 (step S1 in Figure 2) will be explained with reference to the flowchart in Figure 3 and Figures 4 to 12.

[0043] In the first step S1-1, a first multilayer reflecting mirror 102 is laminated on the substrate 101 (see Figure 4). Furthermore, a first cladding layer 103 is laminated on the first multilayer reflecting mirror 102.

[0044] In the next step S1-2, the first active layer 104 is laminated on the first multilayer mirror 102 (see Figure 5). More specifically, the first active layer 104 is laminated on the first cladding layer 103. Furthermore, the first spacer layer 105 is laminated on the first active layer 104.

[0045] In the next step S1-3, the first composition gradient layer 106 is laminated on the first active layer 104 (see Figure 6). More specifically, the first composition gradient layer 106 is laminated on the first spacer layer 105.

[0046] In the next step S1-4, a second p-type semiconductor region 107a2 is stacked on the first composition gradient layer 106 (see Figure 7).

[0047] In the next step S1-5, the first p-type semiconductor region 107a1 is stacked on the second p-type semiconductor region 107a2 (see Figure 8). As a result, a p-type semiconductor layer 107a is formed.

[0048] In the next step S1-6, an n-type semiconductor layer 107b is stacked on the first p-type semiconductor region 107a1 (see Figure 9). As a result, a tunnel junction 107 is formed.

[0049] In the next step S1-7, a second composition gradient layer 108 is stacked on the n-type semiconductor layer 107b (see Figure 10). Furthermore, a second spacer layer 109 is stacked on the second composition gradient layer 108.

[0050] In the next step S1-8, the second active layer 110 is laminated on the second composition gradient layer 108 (see Figure 11). More specifically, the second active layer 110 is laminated on the second spacer layer 109. Furthermore, the second cladding layer 111 is laminated on the second active layer 110.

[0051] In the next step S1-9, a second multilayer reflector 112 is laminated on the second active layer 110 (see Figure 12). More specifically, a second multilayer reflector 112 containing a selectable oxide layer 113S, which becomes a current-constricting layer 113, is laminated on the second cladding layer 111. Furthermore, a contact layer 114 is laminated on the second multilayer reflector 112. As a result, a laminate L1 is formed.

[0052] <Step S2> In step S2, the laminate L1 is etched to form the mesa M1 (see Figure 13). Specifically, a resist pattern is formed on the laminate L1 removed from the growth chamber by photolithography. Then, using this resist pattern as a mask, the laminate L1 is etched, for example, by RIE etching (reactive ion etching) until at least the side surface of the selected oxide layer 113S is exposed (for example, until the side surface of the first cladding layer 103 is completely exposed), thereby forming a mesa M1. The etching is carried out until the etching bottom surface is located inside the first multilayer reflecting mirror 102. After that, the resist pattern is removed.

[0053] <Step S3> In step S3, the area surrounding the selected oxidation layer 113S (see Figure 13) is oxidized to generate the current-constricting layer 113 (see Figure 14). Specifically, the mesa M1 is exposed to a water vapor atmosphere, and the selectively oxidized layer 113S is oxidized from the side (selective oxidation) to form a current-constricted layer 113 in which the non-oxidized region 113a is surrounded by the oxidized region 113b.

[0054] <Step S4> In step S4, an insulating film 115 is formed (see Figure 15). Specifically, the insulating film 115 is deposited over almost the entire area of ​​the laminate on which the mesa M1 is formed.

[0055] <Step S5> In step S5, a contact hole 115a is formed (see Figure 16). Specifically, a resist pattern is formed by photolithography on the insulating film 115 other than the insulating film 115 formed on the top of the mesa M1. Next, using this resist pattern as a mask, the insulating film 115 formed on the top of the mesa M1 is removed by etching using, for example, a hydrofluoric acid-based etchant. After that, the resist pattern is removed. As a result, a contact hole 115a is formed and the contact layer 114 is exposed.

[0056] <Step S6> In step S6, the anode electrode 116 is formed (see Figure 17). Specifically, for example, by EB deposition, a Ti / Pt / Au film is deposited on the contact layer 114 through the contact hole 115a, and the anode electrode 116 is formed in the contact hole 115a by lifting off the resist and the Ti / Pt / Au on the resist.

[0057] <Step S7> In step S7, the cathode electrode 117 is formed (see Figure 18). Specifically, after polishing the back surface (bottom surface) of the substrate 101, a film such as an AuGe / Ni / Au film is deposited on the back surface.

[0058] (4) Effects of surface-emitting lasers The surface-emitting laser 100 according to the first embodiment of this technology comprises first and second multilayer reflectors 102, 112 stacked on top of each other, a plurality of active layers 104, 110 stacked on top of each other between the first and second multilayer reflectors 102, 112, and a tunnel junction 107 disposed between the first and second active layers 104, 110 that are adjacent in the stacking direction. The tunnel junction 107 includes a stacked n-type semiconductor layer 107b and a p-type semiconductor layer 107a, and the p-type semiconductor layer 107a includes a stacked first and second p-type semiconductor regions 107a1, 107a2. In this case, the first and second p-type semiconductor regions 107a1 and 107a2 can be composed of different materials, and each can be given different properties. For example, a p-type semiconductor with a small band gap can be used in the region closer to the n-type semiconductor layer 107b, while a p-type semiconductor with a high carrier concentration can be used in the region further away from the n-type semiconductor layer 107b. As a result, in the p-type semiconductor layer 107a of the tunnel junction 107, it is possible to reduce the voltage drop (lower resistance) in the region near the pn junction, which is the interface between the p-type semiconductor layer 107a and the n-type semiconductor layer 107b, and also to reduce the voltage drop (lower resistance) in regions other than near the pn junction. As a result, the surface-emitting laser 100 of the first embodiment can provide a surface-emitting laser 100 that can reduce the voltage drop at the tunnel junction 107. This makes it possible to realize a surface-emitting laser 100 with excellent emission characteristics.

[0059] The first p-type semiconductor region 107a1 is located between the n-type semiconductor layer 107b and the second p-type semiconductor region 107a2. In this case, for example, by using a material with a small band gap for the first p-type semiconductor region 107a1, it is possible to reduce the resistance in the region near the pn junction of the p-type semiconductor layer 107a.

[0060] The first p-type semiconductor region 107a1 is in contact with the n-type semiconductor layer 107b. In this case, for example, by using a material with a small band gap for the first p-type semiconductor region 107a1, the resistance at the pn junction can be reduced, and the resistance at the tunnel junction 107 can be further reduced.

[0061] The second p-type semiconductor region 107a2 is in contact with the first p-type semiconductor region 107a1. In this case, for example, by using a material with a high carrier concentration in the first p-type semiconductor region 107a1, it is possible to reduce the resistance in regions of the p-type semiconductor layer 107a other than near the pn junction.

[0062] The first p-type semiconductor region 107a1 is in contact with the n-type semiconductor layer 107b, and the second p-type semiconductor region 107a2 is in contact with the first p-type semiconductor region 107a1. In this case, for example, by using a material with a small band gap in the first p-type semiconductor region 107a1 and a material with a high carrier concentration in the first p-type semiconductor region 107a1, it is possible to reduce the resistance throughout the entire p-type semiconductor layer 107a, thereby achieving a significantly lower resistance at the tunnel junction 107.

[0063] Here, ideally, a high carrier concentration is desirable in the first p-type semiconductor region 107a1, but it is difficult to obtain a high carrier concentration in a material that maintains a small band gap. Therefore, it is preferable that the carrier concentration in the second p-type semiconductor region 107a2 is higher than the carrier concentration in the first p-type semiconductor region 107a1.

[0064] It is preferable that the band gap of the first p-type semiconductor region 107a1 is smaller than the band gap of the second p-type semiconductor region 107a2.

[0065] The surface-emitting laser 100 further comprises a first composition gradient layer 106 disposed between the first active layer 104 and the tunnel junction 107. This makes it possible to reduce the resistance between the first active layer 104 and the tunnel junction 107.

[0066] The surface-emitting laser 100 further comprises a second composition gradient layer 108 disposed between the second active layer 110 and the tunnel junction 107. This allows for a gradual change in the Al composition in the region between the second active layer 110 and the tunnel junction 107, thereby reducing the resistance in that region.

[0067] The surface-emitting laser 100 further comprises a first active layer 104, which has a first composition gradient layer 106 positioned between it and the tunnel junction 107, and a first spacer layer 105 positioned between the first composition gradient layer 106 and the first active layer 104, 110. This allows the position of each active layer and the tunnel junction 107 to be controlled in accordance with the light field intensity inside the resonator.

[0068] The surface-emitting laser 100 further comprises a second active layer 110, which has a second composition gradient layer 108 positioned between it and the tunnel junction 107, and a second spacer layer 109 positioned between the second composition gradient layer 108 and the first and second active layers 104 and 110. This allows the position of each active layer and the tunnel junction 107 to be controlled in accordance with the optical field intensity inside the resonator.

[0069] The first p-type semiconductor region 107a1 is preferably made of a GaAs compound semiconductor, an AlGaAs-based compound semiconductor, or an InGaAs-based compound semiconductor.

[0070] The second p-type semiconductor region 107a2 is preferably made of a GaAs compound semiconductor, an AlGaInAs-based compound semiconductor, or an AlGaAs-based compound semiconductor.

[0071] The Al composition of the second p-type semiconductor region 107a2 is preferably greater than the Al composition of the first p-type semiconductor region 107a1.

[0072] The first p-type semiconductor region 107a1 and / or the second p-type semiconductor region 107a2 are preferably doped with at least one of C, Zn, Mg, and Be.

[0073] 2. Surface-emitting lasers according to modified examples 1 to 8 of the first embodiment of this technology The following describes surface-emitting lasers according to modifications 1 to 8 of the first embodiment of this technology.

[0074] (Variation 1) The surface-emitting laser 100-1 of the modified example 1 has the same configuration as the surface-emitting laser 100 of the first embodiment, except that the first composition gradient layer 106 is not provided, as shown in Figure 19. In the surface-emitting laser 100-1, since the first composition gradient layer 106 is not provided, it is inferior to the surface-emitting laser 100 in terms of reducing resistance between the first active layer 104 and the tunnel junction 107. However, it is effective in that the layer structure can be simplified and the number of lamination steps in the laminate production process can be reduced by one.

[0075] (Modification 2) The surface-emitting laser 100-2 of the modified example 2 has the same configuration as the surface-emitting laser 100 of the first embodiment, except that the second composition gradient layer 108 is not provided, as shown in Figure 20. In the surface-emitting laser 100-2, since the second compositionally graded layer 108 is not provided, although it is inferior in terms of reducing the resistance between the second active layer 110 and the tunnel junction 107 compared to the surface-emitting laser 100, it is effective in that the layer structure can be made simpler and the number of stacking steps in the laminate formation process can be reduced by one.

[0076] (Modified Example 3) The surface-emitting laser 100-3 of Modified Example 3 has the same configuration as the surface-emitting laser 100 of the first embodiment, except that the first and second compositionally graded layers 106 and 108 are not provided, as shown in FIG. 21. In the surface-emitting laser 100-3, since the first and second compositionally graded layers 106 and 108 are not provided, although it is inferior in terms of reducing the resistance between the first active layer 104 and the tunnel junction 107 and reducing the resistance between the second active layer 110 and the tunnel junction 107 compared to the surface-emitting laser 100, it is effective in that the layer structure can be made even simpler and the number of stacking steps in the laminate formation process can be reduced by two.

[0077] (Modified Example 4) The surface-emitting laser 100-9 of Modified Example 4 has the same configuration as the surface-emitting laser 100 of the first embodiment, except that the p-type semiconductor layer 107a has a third p-type semiconductor region 107a3 between the first and second p-type semiconductor regions 107a1 and 107a2, as shown in FIG. 22. The third p-type semiconductor region 107a3 may be formed of a material similar to the material of the first p-type semiconductor region 107a1 (e.g., a GaAs-based compound semiconductor) (e.g., a GaAs-based compound semiconductor or an AlGaAs-based compound semiconductor) to have characteristics similar to those of the first semiconductor region 107a1 (e.g., characteristics of a small bandgap). The third p-type semiconductor region 107a3 X may be formed of a material similar to the material of the second p-type semiconductor region 107a2 (e.g., Al Y GaAs) (e.g., Al The third p-type semiconductor region 107a3 is composed of the material of the first p-type semiconductor region 107a1 (e.g., GaAs) and the material of the second p-type semiconductor region 107a2 (e.g., Al X Materials having properties intermediate with GaAs (e.g., Al Y The material may be constructed from GaAs (Y≠X) to provide intermediate characteristics between the first and second p-type semiconductor regions 107a1 and 107a2. Furthermore, two or more p-type semiconductor regions may be provided between the first and second p-type semiconductor regions 107a1 and 107a2. Each of these two or more p-type semiconductor regions can be given the same characteristics as the third p-type semiconductor region 107a3 described above. For example, the p-type semiconductor region closer to the first p-type semiconductor region 107a1 may be given similar characteristics by the first p-type semiconductor region 107a1, and the p-type semiconductor region closer to the second p-type semiconductor region 107a2 may be given similar characteristics by the second p-type semiconductor region 107a2.

[0078] (Variation 5) As shown in Figure 23, the surface-emitting laser 100-10 of Modification 5 has a configuration in which the conductivity types (first and second conductivity types, for example, p-type and n-type) of the layers constituting the surface-emitting laser 100 of the first embodiment are swapped. In this case, the n-type semiconductor layer 107b is placed on the substrate 101 side (lower side) of the p-type semiconductor layer 107a in the tunnel junction 107. The surface-emitting laser 100-10 also produces the same effects as the surface-emitting laser 100 of the first embodiment.

[0079] (Experimental variation 6) The surface-emitting laser 100-11 of Modification 6 has the same configuration as the surface-emitting laser 100-10 of Modification 5, except that the first composition gradient layer 106 is not provided, as shown in Figure 24.

[0080] (Example 7) The surface-emitting laser 100-12 of Modification 7 has the same configuration as the surface-emitting laser 100-10 of Modification 5, except that the second composition gradient layer 108 is not provided, as shown in Figure 25.

[0081] (Variation 8) The surface-emitting laser 100-13 of Modification 8 has the same configuration as the surface-emitting laser 100-10 of Modification 5, except that the first and second composition gradient layers 106 and 108 are not provided, as shown in Figure 26.

[0082] 3. Surface-emitting laser according to the second embodiment of this technology The surface-emitting laser 200 according to the second embodiment of this technology will be described below. (1) Configuration of a surface-emitting laser The surface-emitting laser 200 according to the second embodiment has the same configuration as the surface-emitting laser 100 of the first embodiment, except that the p-type semiconductor layer 107a of the tunnel junction 107 is composed of a single region (it does not have a stacked structure), as shown in Figure 27. In the surface-emitting laser 200, the p-type semiconductor layer 107a is, for example, a high carrier concentration (e.g., 1 x 10⁻¹⁶). 20 cm -3 ~3x10 20 cm -3 It consists of a p-type compound semiconductor (e.g., GaAs-based compound semiconductor, AlGaAs-based compound semiconductor, InGaAs-based compound semiconductor, etc.). The p-type semiconductor layer 107a is preferably doped with at least one of C, Zn, Mg, and Be. For the p-type semiconductor layer 107a, for example, C is doped at a high concentration (e.g., 1 x 10⁻¹⁶). 20 cm -3 A 10nm thick GaAs layer doped in ) can be used. In the surface-emitting laser 200, the n-type semiconductor layer 107b consists of a high-carrier-concentration n-type compound semiconductor (e.g., InGaAs-based compound semiconductor, GaAs-based compound semiconductor, etc.). Preferably, the n-type semiconductor layer 107b is doped with at least one of Si, Te, and Se. As the n-type semiconductor layer 107b, for example, Si is doped with a high concentration (e.g., 5x10⁻¹⁶). 19 cm -3 A 20nm thick GaAs layer doped in ) can be used.

[0083] (2) Operation of surface-emitting laser The surface-emitting laser 200 operates in the same manner as the surface-emitting laser 100.

[0084] (3) Method for manufacturing a surface-emitting laser The manufacturing method for the surface-emitting laser 100 will be described below with reference to the flowchart (steps S11 to S17) in Figure 28. Here, as an example, multiple surface-emitting laser arrays, in which multiple surface-emitting lasers 200 are arranged in two dimensions, are simultaneously generated on a single wafer, which is the substrate 101, using a semiconductor manufacturing method with semiconductor manufacturing equipment. Next, the series of integrated surface-emitting laser arrays are separated from each other to obtain multiple chip-shaped surface-emitting laser arrays (surface-emitting laser array chips). It should be noted that, using the manufacturing method described below, it is also possible to simultaneously generate multiple surface-emitting lasers 200 on a single wafer, which is the substrate 101, and separate the series of integrated surface-emitting lasers 200 from each other to obtain chip-shaped surface-emitting lasers (surface-emitting laser chips).

[0085] <Step S11> In step S11, the laminate formation process 2 is performed. In the laminate formation process 2, as an example, the materials for each layer constituting the surface-emitting laser 200 are sequentially stacked in a growth chamber using a chemical vapor deposition (CVD) method, such as a metal-organic vapor deposition (MOCVD) method, to produce a laminate L2 (see Figure 34).

[0086] The laminate formation process 2 (step S11 in Figure 33) will be explained with reference to the flowchart in Figure 29, Figures 4 to 6, and Figures 30 to 34.

[0087] In the first step S11-1, a first multilayer reflecting mirror 102 is laminated on the substrate 101 (see Figure 4). Furthermore, a first cladding layer 103 is laminated on the first multilayer reflecting mirror 102.

[0088] In the next step, S11-2, the first active layer 104 is laminated on the first multilayer mirror 102 (see Figure 5). More specifically, the first active layer 104 is laminated on the first cladding layer 103. Furthermore, the first spacer layer 105 is laminated on the first active layer 104.

[0089] In the next step, S11-3, the first composition gradient layer 106 is laminated on the first active layer 104 (see Figure 6). More specifically, the first composition gradient layer 106 is laminated on the first spacer layer 105.

[0090] In the next step, S11-4, a p-type semiconductor layer 107a is stacked on the first composition gradient layer 106 (see Figure 30).

[0091] In the next step, S11-5, an n-type semiconductor layer 107b is stacked on top of the p-type semiconductor layer 107a (see Figure 31). As a result, a tunnel junction 107 is formed.

[0092] In the next step, S11-6, a second composition gradient layer 108 is stacked on the n-type semiconductor layer 107b (see Figure 32). Furthermore, a second spacer layer 109 is stacked on the second composition gradient layer 108.

[0093] In the next step, S11-7, the second active layer 110 is laminated on the second composition gradient layer 108 (see Figure 33). More specifically, the second active layer 110 is laminated on the second spacer layer 109. Furthermore, the second cladding layer 111 is laminated on the second active layer 110.

[0094] In the next step S11-8, a second multilayer reflector 112 is laminated on the second active layer 110 (see Figure 34). More specifically, a second multilayer reflector 112 containing a selectable oxide layer 113S, which becomes a current-constricting layer 113, is laminated on the second cladding layer 111. Furthermore, a contact layer 114 is laminated on the second multilayer reflector 112. As a result, a laminate L2 is formed.

[0095] <Step S12> In step S12, the laminate L2 is etched to form the mesa M2 (see Figure 35). Specifically, a resist pattern is formed on the laminate L1 removed from the growth chamber by photolithography. Then, using this resist pattern as a mask, the laminate L1 is etched, for example, by RIE etching (reactive ion etching) until at least the side surface of the selected oxide layer 113S is exposed (for example, until the side surface of the first cladding layer 103 is completely exposed), thereby forming a mesa M1. The etching is carried out until the etching bottom surface is located inside the first multilayer reflecting mirror 102. After that, the resist pattern is removed.

[0096] <Step S13> In step S13, the area surrounding the selected oxidation layer 113S (see Figure 36) is oxidized to generate the current-constricting layer 113. Specifically, the mesa M2 is exposed to a water vapor atmosphere, and the selectively oxidized layer 113S is oxidized from the side (selective oxidation) to form a current-constricted layer 113 in which the non-oxidized region 113a is surrounded by the oxidized region 113b.

[0097] <Step S14> In step S14, an insulating film 115 is formed (see Figure 37). Specifically, the insulating film 115 is deposited over almost the entire area of ​​the laminate on which the mesa M2 is formed.

[0098] <Step S15> In step S15, a contact hole 115a is formed (see Figure 38). Specifically, a resist pattern is formed by photolithography on the insulating film 115 other than the insulating film 115 formed on the top of the mesa M2. Then, using this resist pattern as a mask, the insulating film 115 formed on the top of the mesa M2 is removed by etching using, for example, a hydrofluoric acid-based etchant. After that, the resist pattern is removed. As a result, a contact hole 115a is formed and the contact layer 114 is exposed.

[0099] <Step S16> In step S16, the anode electrode 116 is formed (see Figure 39). Specifically, for example, by EB deposition, a Ti / Pt / Au film is deposited on the contact layer 114 through the contact hole 115a, and the anode electrode 116 is formed in the contact hole 115a by lifting off the resist and the Ti / Pt / Au on the resist.

[0100] <Step S17> In step S17, the cathode electrode 117 is formed (see Figure 40). Specifically, after polishing the back surface (bottom surface) of the substrate 101, a film such as an AuGe / Ni / Au film is deposited on the back surface.

[0101] (4) Effects of surface-emitting lasers The surface-emitting laser 200 of the second embodiment comprises first and second multilayer mirrors 102, 112 stacked on top of each other, a plurality of active layers 104, 110 stacked on top of each other between the first and second multilayer mirrors 102, 112, a tunnel junction 107 disposed between adjacent first and second active layers 104, 110, a first composition gradient layer 106 disposed between the first active layer 104 and the tunnel junction 107, and a second composition gradient layer 108 disposed between the second active layer 110 and the tunnel junction 107. This makes it possible to reduce the voltage drop between the first active layer 104 and the tunnel junction 107, and between the second active layer 110 and the tunnel junction 107, thereby providing a surface-emitting laser with excellent emission characteristics.

[0102] The surface-emitting laser 200 further comprises a first active layer 104, which has a first composition gradient layer 106 positioned between it and the tunnel junction 107, and a first spacer layer 105 positioned between the first composition gradient layer 106 and the first active layer 104, 110. This allows the position of each active layer and the tunnel junction 107 to be controlled in accordance with the light field intensity inside the resonator.

[0103] The surface-emitting laser 200 further comprises a second active layer 110, which has a second composition gradient layer 108 positioned between it and the tunnel junction 107, and a second spacer layer 109 positioned between the second composition gradient layer 108 and the first and second active layers 104 and 110. This allows the position of each active layer and the tunnel junction 107 to be controlled in accordance with the light field intensity inside the resonator.

[0104] In addition, the surface-emitting laser 200 may also have a stacked structure in which the p-type semiconductor layer 107a of the tunnel junction 107 includes a first p-type semiconductor region 107a1 and a second p-type semiconductor region 107a2, similar to the surface-emitting laser 100 of the first embodiment. In this case, the first p-type semiconductor region 107a1 may be placed between the n-type semiconductor layer 107b and the second p-type semiconductor region 107a2. In this case, for example, by using a material with a small band gap for the first p-type semiconductor region 107a1, it is possible to reduce the resistance in the region near the pn junction of the p-type semiconductor layer 107a. In this case, the first p-type semiconductor region 107a1 may be in contact with the n-type semiconductor layer 107b. In this case, for example, by using a material with a small band gap for the first p-type semiconductor region 107a1, the resistance at the pn junction can be reduced, and the resistance at the tunnel junction 107 can be further reduced. In this case, the second p-type semiconductor region 107a2 may be in contact with the first p-type semiconductor region 107a1. In this case, for example, by using a material with a high carrier concentration in the first p-type semiconductor region 107a1, it is possible to reduce the resistance in regions other than the vicinity of the pn junction of the p-type semiconductor layer 107a. In this case, the first p-type semiconductor region 107a1 may be in contact with the n-type semiconductor layer 107b, and the second p-type semiconductor region 107a2 may be in contact with the first p-type semiconductor region 107a1. In this case, for example, by using a material with a small band gap for the first p-type semiconductor region 107a1 and a material with a high carrier concentration for the first p-type semiconductor region 107a1, it is possible to reduce the resistance throughout the entire p-type semiconductor layer 107a, thereby achieving a significantly lower resistance at the tunnel junction 107. Here, ideally, a high carrier concentration is desirable in the first p-type semiconductor region 107a1, but it is difficult to obtain a high carrier concentration in a material that maintains a small band gap. Therefore, it is preferable that the carrier concentration in the second p-type semiconductor region 107a2 is higher than that of the first p-type semiconductor region 107a1. In this case, it is preferable that the band gap of the first p-type semiconductor region 107a1 is smaller than the band gap of the second p-type semiconductor region 107a2. In this case, the first p-type semiconductor region 107a1 is preferably made of a GaAs compound semiconductor, an AlGaAs-based compound semiconductor, or an InGaAs-based compound semiconductor. In this case, the second p-type semiconductor region 107a2 is preferably made of a GaAs compound semiconductor, an AlGaInAs-based compound semiconductor, or an AlGaAs-based compound semiconductor. In this case, it is preferable that the Al composition of the second p-type semiconductor region 107a2 is greater than the Al composition of the first p-type semiconductor region 107a1. In this case, it is preferable that the first p-type semiconductor region 107a1 and / or the second p-type semiconductor region 107a2 are doped with at least one of C, Zn, Mg, and Be.

[0105] 4. Surface-emitting lasers according to modified examples 1 to 14 of the second embodiment of this technology The following describes surface-emitting lasers relating to modifications 1 to 14 of the second embodiment of this technology.

[0106] (Variation 1) The surface-emitting laser 200-1 of the modified example 1 has the same configuration as the surface-emitting laser 200 of the second embodiment, except that the first composition gradient layer 106 is not provided, as shown in Figure 41. In the surface-emitting laser 200-1, since the first composition gradient layer 106 is not provided, it is inferior to the surface-emitting laser 200 in terms of reducing resistance between the first active layer 104 and the tunnel junction 107. However, it is effective in that it simplifies the layer structure and reduces the number of lamination steps by one in the lamination process.

[0107] (Modification 2) The surface-emitting laser 200-2 of the modified example 2 has the same configuration as the surface-emitting laser 200 of the second embodiment, except that the second composition gradient layer 108 is not provided, as shown in Figure 42. In the surface-emitting laser 200-2, since the second composition gradient layer 108 is not provided, it is inferior to the surface-emitting laser 200 in terms of reducing resistance between the second active layer 110 and the tunnel junction 107. However, it is effective in that the layer structure can be simplified and the number of lamination steps in the laminate production process can be reduced by one.

[0108] (Variation 3) As shown in Figure 43, the surface-emitting laser 200-5 of the modified example 3 has a configuration in which the conductivity types (first and second conductivity types, for example, p-type and n-type) of the layers constituting the surface-emitting laser 200 of the second embodiment are swapped. In this case, the n-type semiconductor layer 107b is placed on the substrate 101 side of the p-type semiconductor layer 107a in the tunnel junction 107. The surface-emitting laser 200-5 produces the same effect as the surface-emitting laser 200.

[0109] (Modification 4) The surface-emitting laser 200-6 of Modified Example 4 has the same configuration as the surface-emitting laser 200-5 of Modified Example 3, except that the first composition gradient layer 106 is not provided, as shown in Figure 44.

[0110] (Variation 5) The surface-emitting laser 200-7 of Modified Example 5 has the same configuration as the surface-emitting laser 200-5 of Modified Example 3, except that the second composition gradient layer 108 is not provided, as shown in Figure 45.

[0111] (Experimental variation 6) As shown in Figure 46, the surface-emitting laser 200-8 of the modified example 6 comprises first to third active layers 104-1, 104-2, and 104-3 stacked on top of each other. Each active layer has the same configuration and function as the first active layer 104 described above. The surface-emitting laser 200-8 further comprises a first tunnel junction 107-1 located between adjacent first and second active layers 104-1 and 104-2 in the stacking direction, and a second tunnel junction 107-2 located between adjacent second and third active layers 104-2 and 104-3 in the stacking direction. Each tunnel junction has the same configuration and function as the tunnel junction 107 described above. The surface-emitting laser 200-8 further comprises a first composition gradient layer 106-1 disposed between the first active layer 104-1 and the first tunnel junction 107-1, a second composition gradient layer 106-2 disposed between the second active layer 104-2 and the first tunnel junction 107-1, a third composition gradient layer 106-3 disposed between the second active layer 104-2 and the second tunnel junction 107-2, and a fourth composition gradient layer 106-4 disposed between the third active layer 104-3 and the second tunnel junction 107-2. Each composition gradient layer has the same configuration and function as the first composition gradient layer 106 described above.

[0112] In the surface-emitting laser 200-8, the multiple active layers consist of at least three active layers, including the first to third active layers 104-1, 104-2, and 104-3. Of these at least three active layers, a first tunnel junction 107-1 is positioned between the first and second active layers 104-1 and 104-2, which are the first pair of adjacent active layers (the pair of the first and second active layers 104-1 and 104-2, and the pair of the second and third active layers 104-2 and 104-3), and a second tunnel junction 107-2 is positioned between the second and third active layers 104-2 and 104-3, which are the second pair of adjacent active layers. A first composition gradient layer 106-1 is positioned between a first tunnel junction 107-1, which is one of several (for example, two) tunnel junctions, and a first active layer 104-1, which is one of two adjacent active layers, the first and second active layers 104-1 and 104-2, that sandwich the first tunnel junction 107-1. A second composition gradient layer 106-2 is positioned between the first tunnel junction 107-1 and a second active layer 104-2, which is the other of two adjacent active layers, the first and second active layers 104-1 and 104-2, that sandwich the first tunnel junction 107-1. A third composition gradient layer 106-3 is positioned between a second tunnel junction 107-2, which is the other tunnel junction of a plurality of (for example, two) tunnel junctions, and a second active layer 104-2, which is one of two adjacent active layers, the second and third active layers 104-2 and 104-3, that sandwich the second tunnel junction 107-2. A fourth composition gradient layer 106-4 is positioned between the second tunnel junction 107-2 and a third active layer 104-3, which is the other of two adjacent active layers, the second and third active layers 104-2 and 104-3, that sandwich the second tunnel junction 107-2.

[0113] According to the surface-emitting laser 200-8 of Modification 6, when it has multiple active layers (three or more active layers) and tunnel junctions arranged between the active layers, a composition gradient layer is provided in the region between each active layer and the tunnel junction adjacent to the active layer. This reduces the voltage drop in the region and enables the realization of a surface-emitting laser with excellent emission characteristics.

[0114] (Example 7) The surface-emitting laser 200-9 of Modified Example 7 has the same configuration as the surface-emitting laser 200-8 of Modified Example 6, except that the first and third composition gradient layers 106-1 and 106-3 are not provided, as shown in Figure 47. While surface-emitting laser 200-7 offers a lower degree of improvement in emission characteristics compared to surface-emitting laser 200-8, it is effective in that it allows for a simpler layer configuration and reduces the number of lamination steps required to create the laminate during manufacturing by two.

[0115] (Variation 8) The surface-emitting laser 200-10 of Modified Example 8 has the same configuration as the surface-emitting laser 200-8 of Modified Example 6, except that the second and fourth composition gradient layers 106-2 and 106-4 are not provided, as shown in Figure 48. While the surface-emitting laser 200-10 offers a lower degree of improvement in emission characteristics compared to the surface-emitting laser 200-8, it is effective in that it allows for a simpler layer configuration and reduces the number of layering steps required to create the laminate during manufacturing by two.

[0116] (Extreme variation 9) The surface-emitting laser 200-11 of Modified Example 9 has the same configuration as the surface-emitting laser 200-8 of Modified Example 6, except that the second and third composition gradient layers 106-2 and 106-3 are not provided, as shown in Figure 49. While surface-emitting laser 200-11 offers a lower degree of improvement in emission characteristics compared to surface-emitting laser 200-8, it is effective in that it allows for a simpler layer configuration and reduces the number of lamination steps required to create the laminate during manufacturing by two.

[0117] (Variation 10) The surface-emitting laser 200-12 of Modified Example 10 has the same configuration as the surface-emitting laser 200-8 of Modified Example 6, except that the first and fourth composition gradient layers 106-1 and 106-4 are not provided, as shown in Figure 50. While the surface-emitting laser 200-12 offers a lower degree of improvement in emission characteristics compared to the surface-emitting laser 200-8, it is effective in that it allows for a simpler layer configuration and reduces the number of layering steps required to create the laminate during manufacturing by two.

[0118] (Variation 11) The surface-emitting laser 200-13 of Modified Example 11 has the same configuration as the surface-emitting laser 200-8 of Modified Example 6, except that the first to third composition gradient layers 106-1, 106-2, and 106-3 are not provided, as shown in Figure 51. While surface-emitting laser 200-13 shows less improvement in emission characteristics compared to surface-emitting laser 200-8, it is effective in that it allows for a further simplification of the layer structure and reduces the number of layering steps required to create the laminate during manufacturing by three.

[0119] (Example 12) The surface-emitting laser 200-14 of Modified Example 12 has the same configuration as the surface-emitting laser 200-8 of Modified Example 6, except that the first, second, and fourth composition gradient layers 106-1, 106-2, and 106-4 are not provided, as shown in Figure 52. While the surface-emitting laser 200-14 offers a lower degree of improvement in emission characteristics compared to the surface-emitting laser 200-8, it is effective in that it allows for a further simplification of the layer structure and reduces the number of layering steps required to create the laminate during manufacturing by three.

[0120] (Example 13) The surface-emitting laser 200-15 of Modified Example 13 has the same configuration as the surface-emitting laser 200-8 of Modified Example 6, except that the first, third, and fourth composition gradient layers 106-1, 106-3, and 106-4 are not provided, as shown in Figure 53. While the surface-emitting laser 200-15 offers a lower degree of improvement in emission characteristics compared to the surface-emitting laser 200-8, it is effective in that it allows for a further simplification of the layer structure and reduces the number of layering steps required to create the laminate during manufacturing by three.

[0121] (Variation 14) The surface-emitting laser 200-16 of Modified Example 14 has the same configuration as the surface-emitting laser 200-8 of Modified Example 6, except that the second, third, and fourth composition gradient layers 106-2, 106-3, and 106-4 are not provided, as shown in Figure 54. While surface-emitting laser 200-16 offers a lower degree of improvement in emission characteristics compared to surface-emitting laser 200-8, it is effective in that it allows for a further simplification of the layer structure and reduces the number of layering steps required to produce the laminate during manufacturing by three.

[0122] In the above modifications 6 to 14, we mainly described the case where there are three active layers and two tunnel junctions. However, even in the case where there are four or more active layers and three or more tunnel junctions, similar effects can be obtained by appropriately arranging composition gradient layers, as in the modifications 6 to 14.

[0123] 5. Example configuration of a surface-emitting laser to which this technology can be applied Figure 55 is a plan view showing a surface-emitting laser 2000, which is an example of a surface-emitting laser configuration to which this technology can be applied. Figure 56A is a cross-sectional view taken along line XX of Figure 55. Figure 56B is a cross-sectional view taken along line YY of Figure 55.

[0124] Each component of the surface-emitting laser 2000 is stacked on a substrate 2001. The substrate 2001 can be composed of semiconductors such as GaAs, InGaAs, InP, and InAsP.

[0125] The surface-emitting laser 2000 includes a protective region 2002 (the transmissive gray region in Figures 56A and 56B). As shown in Figure 55, the protective region 2002 is circular in plan view, but may be other shapes such as elliptical or polygonal, and is not limited to a specific shape. The protective region 2002 contains a material that provides electrical isolation, such as an ion-implanted region.

[0126] Furthermore, the surface-emitting laser 2000 includes a first electrode 2003 and a second electrode 2004, as shown in Figures 56A and 56B. As shown in Figure 55, the first electrode 2003 has a ring shape with discontinuous (intermittent) sections in a plan view, i.e., a split-ring shape, but is not limited to a specific shape. As shown in Figure 56A or Figure 56B, the second electrode 2004 is in contact with the substrate 2001. The first electrode 2003 and the second electrode 2004 are composed of conductive materials such as Ti, Pt, Au, AuGeNi, and PdGeAu. The first electrode 2003 and the second electrode 2004 may have a single-layer structure or a multilayer structure.

[0127] Furthermore, the surface-emitting laser 2000 includes trenches 2005 provided around the protective region 2002. Figure 55 shows an example structure in which six rectangular trenches 2005 are provided in plan view, but the number and shape of the trenches in plan view are not limited to any particular type. The trenches 2005 are openings for forming the oxidation constriction layer 2006 (including oxidation regions 2006a and non-oxidation regions 2006b). In the manufacturing process of the surface-emitting laser 2000, high-temperature water vapor is supplied through the trenches 2005 to form the oxidation regions 2006a of the oxidation constriction layer 2006. For example, the oxidation region 2006a is Al2O3 formed as a result of oxidation of the AlAs or AlGaAs layer. After the process of forming the oxidation constriction layer 2006, an arbitrary dielectric material may be embedded in the trenches 2005. Alternatively, a surface coating of a dielectric film may be applied.

[0128] Furthermore, the surface-emitting laser 2000 includes a dielectric aperture 2008 (contact hole) provided in the dielectric layer 2007 on the first electrode 2003. The dielectric layer 2007 may have a multilayer structure as shown in Figures 56A and 56B, or it may have a single-layer structure. The dielectric layer 2007 includes, as an example, silicon oxide or silicon nitride. As shown in Figure 55, the dielectric aperture 2008 is formed in the same shape as the first electrode 2003. However, the shape of the dielectric aperture 2008 is not limited to the shape of the first electrode 2003, and may be partially formed on the first electrode 2003. The dielectric aperture 2008 is filled with a conductive material (not shown), and this conductive material is in contact with the first electrode 2003.

[0129] Furthermore, as shown in Figures 56A and 56B, the surface-emitting laser 2000 includes an optical aperture 2009 inside the first electrode 2003. The surface-emitting laser 2000 emits light rays through the optical aperture 2009. In addition, the surface-emitting laser 2000 has an oxidized region 2006a of the oxidized constriction layer 2006 which functions as a current-light confinement region that confines current and light. The non-oxidized region 2006b of the oxidized constriction layer 2006 is located below the optical aperture 2009 and functions as a current-light passage region that allows current and light to pass through.

[0130] Furthermore, the surface-emitting laser 2000 includes a first multilayer reflector 2011 and a second multilayer reflector 2012. The multilayer reflector is, for example, a semiconductor multilayer reflector, also known as a distributed Bragg reflector.

[0131] Furthermore, the surface-emitting laser 2000 includes an active layer 2013. The active layer 2013 is positioned between the first multilayer reflector 2011 and the second multilayer reflector 2012, confining the injected carriers and defining the emission wavelength of the surface-emitting laser 2000.

[0132] In this example configuration, we have described the case where the surface-emitting laser 2000 is a front-emitting type surface-emitting laser, but the surface-emitting laser 2000 can also be configured as a back-emitting type surface-emitting laser.

[0133] As shown in Figures 55 and 56A, the effective diameter of the surface-emitting laser 2000 in this configuration is the diameter d of the virtual circle defined by the trench 2005.

[0134] The surface-emitting laser 2000 in this example configuration is manufactured, for example, by following the steps 1 to 8 below. (Step 1) A first multilayer reflector 2011, an active layer 2013, a selective oxide layer which will become an oxide constriction layer 2006, and a second multilayer reflector 2012 are epitaxially grown on the surface of the substrate 2001. (Step 2) For example, the first electrode 2003 is formed on the second multilayer reflector 2012 using the lift-off method. (Step 3) For example, trench 2005 is formed by photolithography. (Step 4) The side surface of the selected oxide layer is exposed, and the selected oxide layer is selectively oxidized from the side to form an oxidized constriction layer 2006. (Step 5) A protective region 2002 is formed by ion implantation or the like. (Step 6) The dielectric layer 2007 is formed by, for example, vapor deposition or sputtering. (Step 7) For example, a dielectric opening 2008 is formed in the dielectric layer 2007 by photolithography to expose the contact point of the first electrode 2003. (Step 8) After polishing the back surface of the substrate 2001 to create a thin film, the second electrode 2004 is formed on the back surface of the substrate 2001.

[0135] The number of layers, arrangement, thickness, arrangement order, symmetry, etc., of the layers constituting the surface-emitting laser 2000 described above are examples and can be changed as appropriate. In other words, the surface-emitting laser 2000 may include more layers, fewer layers, different layers, layers with different structures, or layers with different arrangements than those shown in Figures 55, 56A, and 56B.

[0136] This technology can be applied to the surface-emitting laser 2000 and its modified examples described above.

[0137] 6. Variations of this technology This technology is not limited to the embodiments and modifications described above, and various modifications are possible.

[0138] For example, the n-type semiconductor layer of the tunnel junction may be composed of multiple regions made of different materials stacked on top of each other.

[0139] For example, the n-type semiconductor layer of a tunnel junction can be made of a GaAs-based compound semiconductor, such as one with a high concentration of Si (1x10⁻¹⁰). 19 cm -3 A GaAs layer, for example, 20 nm thick, doped with ) may also be used.

[0140] For example, the guide / barrier region of the active layer is made of a GaAsP-based compound semiconductor (e.g., GaAsP 0.10 ) may be composed of these.

[0141] For example, in the p-type semiconductor layer of a tunnel junction, the first p-type semiconductor region may be composed of an InGaAs-based compound semiconductor, and the second p-type semiconductor region may be composed of a GaAs-based compound semiconductor.

[0142] Preferably, the carrier concentrations in the first p-type semiconductor region 107a1 and the second p-type semiconductor region 107a2 are different from each other. For example, the carrier concentration in the first p-type semiconductor region 107a1 may be higher than the carrier concentration in the second p-type semiconductor region 107a2.

[0143] Preferably, the band gaps of the first p-type semiconductor region 107a1 and the second p-type semiconductor region 107a2 are different from each other. For example, the band gap of the second p-type semiconductor region 107a2 may be smaller than the band gap of the first p-type semiconductor region 107a1.

[0144] Preferably, the first p-type semiconductor region 107a1 and the second p-type semiconductor region 107a2 have different carrier concentrations and band gaps.

[0145] The carrier concentrations in the first p-type semiconductor region 107a1 and the second p-type semiconductor region 107a2 may be the same.

[0146] The band gaps of the first p-type semiconductor region 107a1 and the second p-type semiconductor region 107a2 may be the same.

[0147] The Al compositions of the first p-type semiconductor region 107a1 and the second p-type semiconductor region 107a2 are preferably different from each other. For example, the Al composition of the second p-type semiconductor region 107a2 may be smaller than the Al composition of the first p-type semiconductor region 107a1.

[0148] The Al composition of the first p-type semiconductor region 107a1 and the second p-type semiconductor region 107a2 may be the same.

[0149] In the surface-emitting laser according to this technology, the current-constricting layer 113 is not necessarily provided.

[0150] In the surface-emitting laser according to this technology, the contact layer 114 is not necessarily provided.

[0151] In each of the embodiments and modifications described above, both the first and second multilayer reflectors 102 and 112 are semiconductor multilayer reflectors, but are not limited to these. For example, the first multilayer mirror 102 may be a semiconductor multilayer mirror, and the second multilayer mirror 112 may be a dielectric multilayer mirror. A dielectric multilayer mirror is also a type of distributed Bragg mirror. For example, the first multilayer mirror 102 may be a dielectric multilayer mirror, and the second multilayer mirror 112 may be a semiconductor multilayer mirror. For example, both the first and second multilayer reflectors 102 and 112 may be dielectric multilayer reflectors. Semiconductor multilayer reflectors have low light absorption and are conductive. From this viewpoint, semiconductor multilayer reflectors are suitable for a second multilayer reflector 112 located on the output side (surface side) and on the current path from the anode electrode 116 to each active layer. On the other hand, dielectric multilayer reflectors have extremely low light absorption. From this viewpoint, dielectric multilayer reflectors are suitable for the second multilayer reflector 112 located on the exit side (surface side).

[0152] In the above embodiments and modifications, a surface-emitting laser that emits laser light from the top of a mesa was used as an example. However, this technology is also applicable to a back-emitting laser that emits laser light from the back surface of a substrate. In this case, it is preferable to use a substrate that is transparent to the oscillation wavelength, or to provide an opening in the substrate that serves as the emission port.

[0153] In the above embodiments and modifications, a surface-emitting laser 10 using an AlGaAs-based compound semiconductor was described as an example, but this technology can also be applied to surface-emitting lasers using, for example, a GaN-based compound semiconductor. Specifically, a GaN-based semiconductor multilayer mirror may be used for at least one of the first and second multilayer mirrors 102 and 112, or a GaN-based dielectric multilayer mirror may be used for at least one of the first and second multilayer mirrors 102 and 112. Examples of GaN-based compound semiconductors used in at least one of the first and second multilayer reflecting mirrors 102 and 112 include GaN / AlGaN.

[0154] Some of the configurations of the surface-emitting lasers in each of the above embodiments and their respective modifications may be combined within a range that is not inconsistent with each other.

[0155] In each of the embodiments and modifications described above, the material, conductivity type, dope concentration, thickness, width, etc., of each layer constituting the surface-emitting laser can be appropriately changed within the range in which it functions as a surface-emitting laser.

[0156] 7. Examples of applications in electronic devices The technology disclosed herein (the Technology) can be applied to various products (electronic devices). For example, the Technology disclosed herein may be implemented as a device mounted on any type of mobile vehicle, such as an automobile, electric vehicle, hybrid electric vehicle, motorcycle, bicycle, personal mobility device, airplane, drone, ship, or robot.

[0157] The surface-emitting laser related to this technology can be applied, for example, as a light source for devices that form or display images using laser light (e.g., laser printers, laser copiers, projectors, head-mounted displays, head-up displays, etc.).

[0158] 8. <Example of applying a surface-emitting laser to a distance measuring device> The following describes application examples of surface-emitting lasers according to each of the above embodiments and their respective modifications.

[0159] Figure 57 shows an example of the schematic configuration of a distance measuring device 1000 equipped with a surface-emitting laser 100, as an example of an electronic device relating to this technology. The distance measuring device 1000 measures the distance to a subject S using the TOF (Time Of Flight) method. The distance measuring device 1000 is equipped with a surface-emitting laser 100 as a light source. The distance measuring device 1000 includes, for example, a surface-emitting laser 100, a light receiving device 120, lenses 119 and 130, a signal processing unit 140, a control unit 150, a display unit 160, and a storage unit 170.

[0160] The light receiving device 120 detects the light reflected from the subject S. Lens 119 is a collimating lens that aligns the light emitted from the surface-emitting laser 100. Lens 130 is a focusing lens that collects the light reflected from the subject S and guides it to the light receiving device 120.

[0161] The signal processing unit 140 is a circuit for generating a signal corresponding to the difference between the signal input from the light receiving device 120 and the reference signal input from the control unit 150. The control unit 150 is configured to include, for example, a Time to Digital Converter (TDC). The reference signal is the control unit The signal may be input from 150, or it may be the output signal of a detection unit that directly detects the output of the surface-emitting laser 100. The control unit 150 is, for example, a processor that controls the surface-emitting laser 100, the light receiving device 120, the signal processing unit 140, the display unit 160, and the storage unit 170. The control unit 150 is a circuit that measures the distance to the subject S based on the signal generated by the signal processing unit 140. The control unit 150 generates a video signal for displaying information about the distance to the subject S and outputs it to the display unit 160. The display unit 160 displays information about the distance to the subject S based on the video signal input from the control unit 150. The control unit 150 stores the information about the distance to the subject S in the storage unit 170.

[0162] In this application example, instead of the surface-emitting laser 100, any of the surface-emitting lasers 100-1 to 100-13, 200, or 200-1 to 200-16 can also be applied to the distance measuring device 1000. 9. <Example of mounting a distance measuring device on a mobile device>

[0163] Figure 58 is a block diagram showing a schematic configuration example of a vehicle control system, which is an example of a mobile control system to which the technology described herein may be applied.

[0164] The vehicle control system 12000 comprises multiple electronic control units connected via a communication network 12001. In the example shown in Figure 58, the vehicle control system 12000 includes a drive system control unit 12010, a body system control unit 12020, an external information detection unit 12030, an internal information detection unit 12040, and an integrated control unit 12050. The functional configuration of the integrated control unit 12050 is shown in the figure, consisting of a microcomputer 12051, an audio / image output unit 12052, and an in-vehicle network interface 12053.

[0165] The drivetrain control unit 12010 controls the operation of devices related to the vehicle's drivetrain according to various programs. For example, the drivetrain control unit 12010 functions as a control device for a drivetrain generating device that generates driving force for the vehicle, such as an internal combustion engine or a drive motor; a drivetrain transmission mechanism that transmits driving force to the wheels; a steering mechanism that adjusts the steering angle of the vehicle; and a braking device that generates braking force for the vehicle.

[0166] The body system control unit 12020 controls the operation of various devices mounted on the vehicle body according to various programs. For example, the body system control unit 12020 functions as a control device for a keyless entry system, a smart key system, a power window system, or various lamps such as headlights, reverse lights, brake lights, turn signals, or fog lights. In this case, the body system control unit 12020 may receive radio waves transmitted from a portable device that replaces a key or signals from various switches. The body system control unit 12020 receives these radio waves or signals and controls the vehicle's door lock system, power window system, lamps, etc.

[0167] The external information detection unit 12030 detects information from outside the vehicle equipped with the vehicle control system 12000. For example, a distance measuring device 12031 is connected to the external information detection unit 12030. The distance measuring device 12031 includes the distance measuring device 1000 described above. The external information detection unit 12030 causes the distance measuring device 12031 to measure the distance to an object outside the vehicle (subject S) and acquires the distance data obtained thereby. Based on the acquired distance data, the external information detection unit 12030 may perform object detection processing for people, cars, obstacles, signs, etc.

[0168] The in-vehicle information detection unit 12040 detects information inside the vehicle. The in-vehicle information detection unit 12040 is connected to, for example, a driver status detection unit 12041 that detects the driver's state. The driver status detection unit 12041 includes, for example, a camera that images the driver, and the in-vehicle information detection unit 12040 may calculate the driver's level of fatigue or concentration, or determine whether the driver is drowsy, based on the detection information input from the driver status detection unit 12041.

[0169] The microcomputer 12051 can calculate control target values ​​for the drive force generator, steering mechanism, or braking system based on information from inside and outside the vehicle acquired by the external information detection unit 12030 or the internal information detection unit 12040, and output control commands to the drive system control unit 12010. For example, the microcomputer 12051 can perform cooperative control aimed at realizing ADAS (Advanced Driver Assistance System) functions, including collision avoidance or impact mitigation, following based on distance between vehicles, maintaining vehicle speed, vehicle collision warning, or vehicle lane departure warning.

[0170] Furthermore, the microcomputer 12051 can perform cooperative control for purposes such as autonomous driving, where the vehicle drives autonomously without driver intervention, by controlling the drive force generating device, steering mechanism, or braking device, etc., based on information about the vehicle's surroundings acquired by the external information detection unit 12030 or the internal information detection unit 12040.

[0171] Furthermore, the microcomputer 12051 can output control commands to the body system control unit 12020 based on external information acquired by the external information detection unit 12030. For example, the microcomputer 12051 can control the headlights according to the position of a preceding or oncoming vehicle detected by the external information detection unit 12030, and perform coordinated control aimed at reducing glare, such as switching from high beams to low beams.

[0172] The audio-image output unit 12052 transmits at least one of audio and image output signals to an output device capable of visually or audibly notifying information to the vehicle's occupants or to those outside the vehicle. In the example shown in Figure 58, the output devices include an audio speaker 12061, a display unit 12062, and an instrument panel 12063. The display unit 12062 may include, for example, at least one of an onboard display and a head-up display.

[0173] Figure 59 shows an example of the installation location of the distance measuring device 12031.

[0174] In Figure 59, vehicle 12100 has distance measuring devices 12101, 12102, 12103, 12104, and 12105 as distance measuring device 12031.

[0175] The distance measurement devices 12101, 12102, 12103, 12104, and 12105 are provided, for example, at positions such as the front nose, side mirrors, rear bumper, back door of the vehicle 12100, and the upper part of the front glass inside the vehicle cabin. The distance measurement device 12101 provided at the front nose and the distance measurement device 12105 provided at the upper part of the front glass inside the vehicle cabin mainly acquire data in front of the vehicle 12100. The distance measurement devices 12102 and 12103 provided at the side mirrors mainly acquire data on the sides of the vehicle 12100. The distance measurement device 12104 provided at the rear bumper or the back door mainly acquires data behind the vehicle 12100. The front data acquired by the distance measurement devices 12101 and 12105 is mainly used for detecting a preceding vehicle or pedestrians, obstacles, traffic lights, traffic signs, etc.

[0176] Note that FIG. 59 shows an example of the detection ranges of the distance measurement devices 12101 to 12104. The detection range 12111 indicates the detection range of the distance measurement device 12101 provided at the front nose, the detection ranges 12112 and 12113 respectively indicate the detection ranges of the distance measurement devices 12102 and 12103 provided at the side mirrors, and the detection range 12114 indicates the detection range of the distance measurement device 12104 provided at the rear bumper or the back door.

[0177] For example, based on the distance data obtained from the distance measurement devices 12101 to 12104, the microcomputer 12051 determines the distance to each solid object within the detection ranges 12111 to 12114 and the temporal change of this distance (relative speed with respect to the vehicle 12100), and can extract, as the preceding vehicle, the solid object that is the closest on the traveling path of the vehicle 12100 and travels in substantially the same direction as the vehicle 12100 at a predetermined speed (for example, 0 km / h or more). Furthermore, the microcomputer 12051 can set the inter-vehicle distance that should be secured in advance in front of the preceding vehicle and perform automatic brake control (including follow-up stop control) and automatic acceleration control (including follow-up start control), etc. Thus, cooperative control for the purpose of autonomous driving, etc., which runs autonomously without relying on the driver's operation, can be performed.

[0178] For example, based on the distance data obtained from the distance measurement devices 12101 to 12104, the microcomputer 12051 classifies and extracts solid object data regarding solid objects into categories such as motorcycles, ordinary vehicles, large vehicles, pedestrians, utility poles, and other solid objects, and can use it for automatic avoidance of obstacles. For example, the microcomputer 12051 discriminates obstacles around the vehicle 12100 into obstacles visible to the driver of the vehicle 12100 and obstacles difficult to visually recognize. Then, the microcomputer 12051 determines a collision risk indicating the degree of risk of collision with each obstacle, and when the collision risk is at or above a set value and there is a possibility of collision, it outputs an alarm to the driver via the audio speaker 12061 or the display unit 12062, or performs forced deceleration or avoidance steering via the drive system control unit 12010, thereby providing driving assistance for collision avoidance.

[0179] As described above, an example of a movement control system to which the technology according to the present disclosure can be applied has been described. The technology according to the present disclosure can be applied to the distance measurement device 12031 among the configurations described above.

[0180] The specific numerical values, shapes, materials (including compositions), etc. described in this specification are merely examples and are not limited thereto.

[0181] Also, the present technology can also have the following configuration. (1) First and second multilayer film reflectors, a plurality of active layers laminated with each other between the first and second multilayer film reflectors, <000"914>a tunnel junction disposed between the first and second active layers adjacent to each other in the lamination direction among the plurality of active layers, and the tunnel junction includes an n-type semiconductor layer and a p-type semiconductor layer laminated with each other, the p-type semiconductor layer includes first and second p-type semiconductor regions laminated with each other, a surface-emitting laser. (2) The surface-emitting laser according to (1), wherein the first p-type semiconductor region is disposed between the n-type semiconductor layer and the second p-type semiconductor region. (3) The surface-emitting laser according to (1) or (2), wherein the first p-type semiconductor region is in contact with the n-type semiconductor layer. (4) The second p-type semiconductor region is in contact with the first p-type semiconductor region, and the surface-emitting laser is as described in any one of (1) to (3). (5) A surface-emitting laser according to any one of (1) to (4), wherein the carrier concentrations of the first p-type semiconductor region and the second p-type semiconductor region are different from each other. (6) The band gaps of the first p-type semiconductor region and the second p-type semiconductor region are different from each other, the surface-emitting laser according to any one of (1) to (5). (7) The surface-emitting laser according to any one of (1) to (6), wherein the carrier concentration in the second p-type semiconductor region is higher than the carrier concentration in the first p-type semiconductor region. (8) The surface-emitting laser according to any one of (1) to (7), wherein the band gap of the first p-type semiconductor region is smaller than the band gap of the second p-type semiconductor region. (9) A surface-emitting laser according to any one of (1) to (18), further comprising a composition gradient layer disposed between the first active layer and the tunnel junction and / or between the second active layer and the tunnel junction. (10) The surface-emitting laser according to (9), further comprising an active layer among the first and second active layers in which the composition gradient layer is disposed between the tunnel junction and an active layer, and a spacer layer disposed between the composition gradient layer. (11) The surface-emitting laser according to any one of (1) to (10), wherein the plurality of active layers are at least three active layers including the first and second active layers, the tunnel junctions are arranged between two adjacent active layers of each of the plurality of pairs of adjacent active layers, and a composition gradient layer is arranged between at least one of the plurality of tunnel junctions and at least one of the two adjacent active layers that sandwich the tunnel junction. (12) The surface-emitting laser according to any one of (1) to (11), wherein the first p-type semiconductor region is made of a GaAs compound semiconductor, an AlGaAs-based compound semiconductor, or an InGaAs-based compound semiconductor. (13) The surface-emitting laser according to any one of (1) to (12), wherein the second p-type semiconductor region is made of a GaAs compound semiconductor, an AlGaInAs-based compound semiconductor, or an AlGaAs-based compound semiconductor. (14) The surface-emitting laser according to any one of claims (1) to (13), wherein the Al composition of the first p-type semiconductor region and the second p-type semiconductor region are different from each other. (15) A surface-emitting laser according to any one of (1) to (14), wherein the Al composition of the second p-type semiconductor region is greater than the Al composition of the first p-type semiconductor region. (16) A surface-emitting laser according to any one of (1) to (15), wherein the first p-type semiconductor region and / or the second p-type semiconductor region are doped with at least one of C, Zn, Mg, and Be. (17) First and second multilayer reflecting mirrors, A plurality of active layers stacked on top of each other between the first and second multilayer reflecting mirrors, A tunnel junction is disposed between adjacent first and second active layers among the plurality of active layers, A composition gradient layer disposed between the first active layer and the tunnel junction and / or between the second active layer and the tunnel junction, A surface-emitting laser equipped with the following features. (18) The surface-emitting laser according to (17), further comprising an active layer among the first and second active layers in which the composition gradient layer is disposed between the tunnel junction and an active layer, and a spacer layer disposed between the composition gradient layer. (19) The surface-emitting laser according to (17) or (18), wherein the plurality of active layers are at least three active layers including the first and second active layers, the tunnel junctions are arranged between two adjacent active layers of each of the plurality of pairs of adjacent active layers, and a composition gradient layer is arranged between at least one of the plurality of tunnel junctions and at least one of the two adjacent active layers that sandwich the one tunnel junction. (20) The surface-emitting laser according to any one of (17) to (19), wherein the tunnel junction includes an n-type semiconductor layer and a p-type semiconductor layer stacked on top of each other, and the p-type semiconductor layer includes first and second p-type semiconductor regions stacked on top of each other. (21) The surface-emitting laser according to (20), wherein the first p-type semiconductor region is located between the n-type semiconductor layer and the second p-type semiconductor region. (22) The surface-emitting laser according to (20) or (21), wherein the first p-type semiconductor region is in contact with the n-type semiconductor layer. (23) The surface-emitting laser according to any one of (20) to (22), wherein the second p-type semiconductor region is in contact with the first p-type semiconductor region. (24) A surface-emitting laser according to any one of (20) to (23), wherein the carrier concentrations of the first p-type semiconductor region and the second p-type semiconductor region are different from each other. (25) A surface-emitting laser according to any one of (20) to (24), wherein the band gaps of the first p-type semiconductor region and the second p-type semiconductor region are different from each other. (26) The surface-emitting laser according to any one of (20) to (25), wherein the carrier concentration in the second p-type semiconductor region is higher than the carrier concentration in the first p-type semiconductor region. (27) A surface-emitting laser according to any one of (20) to (26), wherein the band gap of the first p-type semiconductor region is smaller than the band gap of the second p-type semiconductor region. (28) The surface-emitting laser according to any one of (20) to (27), wherein the first p-type semiconductor region is made of a GaAs compound semiconductor, an AlGaAs-based compound semiconductor, or an InGaAs-based compound semiconductor. (29) The surface-emitting laser according to any one of (20) to (28), wherein the second p-type semiconductor region is made of a GaAs compound semiconductor, an AlGaInAs-based compound semiconductor, or an AlGaAs-based compound semiconductor. (30) A surface-emitting laser according to any one of (20) to (29), wherein the Al composition of the first p-type semiconductor region and the second p-type semiconductor region are different from each other. (31) A surface-emitting laser according to any one of (20) to (30), wherein the Al composition of the second p-type semiconductor region is greater than the Al composition of the first p-type semiconductor region. (32) The surface-emitting laser according to any one of (20) to (31), wherein the first p-type semiconductor region and / or the second p-type semiconductor region are doped with at least one of C, Zn, Mg, and Be. (33) A surface-emitting laser array in which any one of the surface-emitting lasers described in (1) to (32) is arranged in two dimensions. (34) An electronic device equipped with a surface-emitting laser as described in (1) to (32). (35)(33) An electronic device comprising a surface-emitting laser array as described above. [Explanation of symbols]

[0182] 100, 100-1~100-13, 200, 200-1~200-16: Surface-emitting laser, 101: Substrate, 102: First multilayer reflector, 104, 104-1: First active layer, 105: First spacer layer (spacer layer), 106, 106-1: First composition gradient layer (composition gradient layer), 107: Tunnel junction, 107-1: First tunnel junction (tunnel junction), 107-2: Second tunnel junction (tunnel junction 107-3: Third tunnel junction (tunnel junction), 107-4: Fourth tunnel junction (tunnel junction), 107a: p-type semiconductor layer, 107a1: First p-type semiconductor region, 107a2: Second p-type semiconductor region, 107b: n-type semiconductor layer, 108, 108-2: Second composition gradient layer (composition gradient layer), 109: Second spacer layer (spacer layer), 110, 104-2: Second active layer, 112: Second multilayer reflector.

Claims

1. First and second multilayer reflecting mirrors, A plurality of active layers stacked on top of each other between the first and second multilayer reflecting mirrors, A tunnel junction is disposed between the first and second active layers, which are adjacent to each other in the stacking direction, among the plurality of active layers. Equipped with, The tunnel junction includes an n-type semiconductor layer and a p-type semiconductor layer stacked on top of each other. The p-type semiconductor layer includes first and second p-type semiconductor regions stacked on top of each other. The first p-type semiconductor region is arranged between the n-type semiconductor layer and the second p-type semiconductor region. The Al composition of the second p-type semiconductor region is greater than the Al composition of the first p-type semiconductor region. The n-type semiconductor layer is made of an InGaAs-based compound semiconductor or a GaAs-based compound semiconductor. The first p-type semiconductor region consists of a GaAs compound semiconductor, an AlGaAs-based compound semiconductor, or an InGaAs-based compound semiconductor. The present invention further comprises a composition gradient layer disposed between one of the first and second active layers, which is located on the surface side of the second p-type semiconductor region of the tunnel junction, and the tunnel junction. A surface-emitting laser in which the composition gradient layer gradually or stepwise decreases the Al composition from the one active layer side to the tunnel junction side so as to approach the Al composition of the second p-type semiconductor region.

2. The system further comprises the other active layer among the first and second active layers, located on the surface side of the tunnel junction on the n-type semiconductor layer side, and another composition gradient layer disposed between the tunnel junction, The surface-emitting laser according to claim 1, wherein the Al composition of the other composition gradient layer gradually or stepwise decreases from the other active layer side to the tunnel junction side so as to approach the Al composition of the n-type semiconductor layer.

3. The surface-emitting laser according to claim 1 or 2, wherein the first p-type semiconductor region is in contact with the n-type semiconductor layer.

4. The surface-emitting laser according to any one of claims 1 to 3, wherein the second p-type semiconductor region is in contact with the first p-type semiconductor region.

5. The surface-emitting laser according to any one of claims 1 to 4, wherein the carrier concentrations in the first p-type semiconductor region and the second p-type semiconductor region are different from each other.

6. The surface-emitting laser according to any one of claims 1 to 5, wherein the band gaps of the first p-type semiconductor region and the second p-type semiconductor region are different from each other.

7. The surface-emitting laser according to any one of claims 1 to 6, wherein the carrier concentration in the second p-type semiconductor region is higher than the carrier concentration in the first p-type semiconductor region.

8. The surface-emitting laser according to any one of claims 1 to 7, wherein the band gap of the first p-type semiconductor region is smaller than the band gap of the second p-type semiconductor region.

9. A surface-emitting laser according to any one of claims 1 to 8, further comprising an active layer having the composition gradient layer disposed between the first and second active layers and the tunnel junction, and a spacer layer disposed between the composition gradient layer.

10. The plurality of active layers are at least three active layers, including the first and second active layers. The tunnel junction is positioned between two adjacent active layers in each pair of adjacent active layers from among the multiple pairs of active layers. At least one of the multiple tunnel junctions, The surface-emitting laser according to any one of claims 1 to 9, wherein the composition gradient layer is disposed between at least one of the two adjacent active layers that straddle the one tunnel junction.

11. The surface-emitting laser according to any one of claims 1 to 10, wherein the second p-type semiconductor region is made of a GaAs compound semiconductor, an AlGaInAs-based compound semiconductor, or an AlGaAs-based compound semiconductor.

12. The surface-emitting laser according to any one of claims 1 to 11, wherein the first p-type semiconductor region and / or the second p-type semiconductor region are doped with at least one of C, Zn, Mg, and Be.

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