Surface-emitting laser, electronic device, and method of manufacturing surface-emitting laser

Abstract

To provide a surface emitting laser capable of suppressing a decrease in luminous efficiency.SOLUTION: The present technology provides a surface emitting laser 100 including: first and second multilayer film reflectors 102, 112; a plurality of active layers 104-1, 104-2 laminated together between the first and second multilayer film reflectors; a tunnel junction 108 disposed between two active layers adjacent to each other in a lamination direction among the plurality of active layers; and an oxide confinement layer 106 disposed between one active layer of the two adjacent active layers and the tunnel junction. According to the present technology, it is possible to provide a surface emitting laser capable of suppressing a decrease in luminous efficiency.SELECTED DRAWING: Figure 1

Description

[Technical Field]

[0001] The technology according to the present disclosure (hereinafter also referred to as "the technology") relates to a surface-emitting laser, an electronic device, and a method for manufacturing a surface-emitting laser. [Background technology]

[0002] Conventionally, surface-emitting lasers have been known in which an active layer is disposed between first and second multilayer reflectors. Among these surface-emitting lasers, there is one in which a tunnel junction, an active layer, and a current confinement layer are stacked in this order between the first and second multilayer reflectors (see, for example, Patent Document 1). [Prior art documents] [Patent documents]

[0003] [Patent Document 1] Japanese Patent Application Laid-Open No. 2006-351798 Summary of the Invention [Problem to be solved by the invention]

[0004] However, conventional surface-emitting lasers have room for improvement in terms of suppressing the decrease in light-emitting efficiency.

[0005] Therefore, a main object of the present technology is to provide a surface-emitting laser that can suppress a decrease in light emission efficiency. [Means for solving the problem]

[0006] This technology comprises first and second multilayer film reflectors, a plurality of active layers stacked one on top of the other between the first and second multilayer film reflectors; a tunnel junction disposed between two active layers adjacent to each other in a stacking direction among the plurality of active layers; an oxide constriction layer disposed between one of the two adjacent active layers and the tunnel junction; A surface-emitting laser is provided, comprising: The one active layer may be disposed at a position farther from the emission surface of the surface-emitting laser than the other active layer of the two adjacent active layers. The one active layer may be disposed closer to one of the first and second multilayer film reflectors that is farther from the emission surface than to the other of the first and second multilayer film reflectors that is closer to the emission surface. The one active layer may be disposed closer to the other of the first and second multilayer film reflectors that is closer to the emission surface than one of the first and second multilayer film reflectors that is farther from the emission surface. The one active layer may be disposed at a position closer to the emission surface of the surface-emitting laser than the other active layer of the two adjacent active layers. The one active layer may be disposed closer to one of the first and second multilayer film reflectors that is farther from the emission surface than to the other of the first and second multilayer film reflectors that is closer to the emission surface. The one active layer may be disposed closer to the other of the first and second multilayer film reflectors that is closer to the emission surface than one of the first and second multilayer film reflectors that is farther from the emission surface. The plurality of active layers may be at least three active layers, and the tunnel junction may be disposed between two adjacent active layers of each set of at least two sets of two adjacent active layers among the plurality of active layers, and the oxide constriction layer may be disposed between one active layer of at least one set of two adjacent active layers among the at least two sets of two adjacent active layers and the tunnel junction disposed between the two adjacent active layers. The at least three active layers may include first, second, and third active layers, which are stacked in this order, a first tunnel junction that is the tunnel junction may be disposed between the first and second active layers, a second tunnel junction that is the tunnel junction may be disposed between the second and third active layers, and the oxide constriction layer may be disposed between the first active layer and the first tunnel junction and / or between the second active layer and the second tunnel junction. The first active layer may be the active layer disposed at a position farthest from the emission surface of the surface-emitting laser among the plurality of active layers. A first oxide constriction layer, which is the oxide constriction layer, may be disposed between the first active layer and the first tunnel junction. A second oxide constriction layer, which is the oxide constriction layer, may be disposed between the second active layer and the second tunnel junction. The oxide constriction layer may not be disposed between the second active layer and the second tunnel junction. Another oxide constriction layer may be disposed inside one of the first and second multilayer film reflectors that is closer to the emission surface of the surface-emitting laser. The oxidized constriction layer and the additional oxidized constriction layer may both be formed by selectively oxidizing a layer made of an AlGaAs-based compound semiconductor. The oxidized constriction layer and the additional oxidized constriction layer may differ from each other in Al composition and / or optical thickness. The tunnel junction may have a layer structure in which a p-type semiconductor layer and an n-type semiconductor layer are stacked on top of each other, and the oxide constriction layer may be disposed on the p-type semiconductor layer side. When the oscillation wavelength of the surface-emitting laser is λ, the one active layer, the tunnel junction, and the oxide constriction layer may be arranged within an optical thickness of 3λ / 4. The present technology also provides an electronic device including the surface-emitting laser. The present technology includes a step of forming a stack by stacking a structure including a stacked structure in which a first active layer, a selectively oxidized layer, a tunnel junction, and a second active layer are stacked in this order on a first multilayer reflector, and then stacking at least a second multilayer reflector on the structure; forming a mesa by etching the stacked body until at least the side surface of the selectively oxidized layer is exposed; a step of selectively oxidizing the selectively oxidized layer from a side surface thereof to form an oxidized constriction layer; Also provided is a method for manufacturing a surface-emitting laser, including: [Brief explanation of the drawings]

[0007] [Figure 1] 1 is a cross-sectional view showing a configuration of a surface-emitting laser according to a first embodiment of the present technology. [Figure 2] 5 is a flowchart for explaining a method for manufacturing a surface-emitting laser according to the first embodiment of the present technology. [Figure 3] 3 is a flowchart for explaining the first step (laminate body generating process 1) of FIG. 2. [Figure 4] FIG. 4 is a first process diagram of FIG. 3. [Figure 5] 4 is a flowchart for explaining the second step (resonator substrate producing step 1) of FIG. 3. [Figure 6] FIG. 6 is a diagram showing the first lamination process of FIG. 5. [Figure 7] FIG. 6 is a diagram showing the second lamination process of FIG. 5. [Figure 8] FIG. 6 is a diagram showing the third lamination process of FIG. 5. [Figure 9] FIG. 6 is a diagram showing the fourth lamination process of FIG. 5. [Figure 10] FIG. 6 is a diagram showing the fifth lamination step of FIG. 5. [Figure 11] FIG. 4 is a diagram showing the third process of FIG. 3. [Figure 12] FIG. 3 is a second process diagram of FIG. 2. [Figure 13] FIG. 3 is a diagram showing the third process in FIG. 2. [Figure 14] FIG. 4 is a diagram showing the fourth step in FIG. 2. [Figure 15] FIG. 5 is a diagram showing the fifth step in FIG. 2. [Figure 16] FIG. 6 is a diagram showing the sixth step in FIG. 2. [Figure 17] FIG. 7 is a diagram showing the seventh step in FIG. 2. [Figure 18] 1 is a cross-sectional view showing a configuration of a surface-emitting laser according to a first modified example of the first embodiment of the present technology. [Figure 19] 10 is a cross-sectional view showing a configuration of a surface-emitting laser according to a second modification of the first embodiment of the present technology. FIG. [Figure 20] FIG. 10 is a cross-sectional view showing a configuration of a surface-emitting laser according to a third modification of the first embodiment of the present technology. [Figure 21] FIG. 10 is a cross-sectional view showing a configuration of a surface-emitting laser according to a fourth modified example of the first embodiment of the present technology. [Figure 22]FIG. 10 is a cross-sectional view showing a configuration of a surface-emitting laser according to a fifth modified example of the first embodiment of the present technology. [Figure 23] FIG. 4 is a cross-sectional view showing a configuration of a surface-emitting laser according to a second embodiment of the present technology. [Figure 24] 10 is a flowchart illustrating a method for manufacturing a surface-emitting laser according to a second embodiment of the present technology. [Figure 25] 25 is a flowchart for explaining the first step (laminate body generating process 2) of FIG. 24. [Figure 26] 26 is a flowchart for explaining the second step (resonator substrate generating step 2) in FIG. 25. [Figure 27] FIG. 27 is a diagram showing the third lamination process of FIG. 26. [Figure 28] FIG. 27 is a diagram showing the fourth lamination process of FIG. 26. [Figure 29] FIG. 27 is a diagram showing the fifth lamination process of FIG. 26. [Figure 30] FIG. 27 is a diagram showing the sixth lamination step of FIG. 26. [Figure 31] FIG. 27 is a diagram showing the seventh lamination step of FIG. 26. [Figure 32] FIG. 26 is a diagram showing the third step in FIG. 25. [Figure 33] FIG. 25 is a second process diagram of FIG. 24. [Figure 34] FIG. 25 is a diagram showing the third step in FIG. 24. [Figure 35] FIG. 25 is a diagram showing the fourth step in FIG. 24. [Figure 36] FIG. 25 is a diagram showing the fifth step in FIG. 24. [Figure 37] FIG. 25 is a diagram showing the sixth step in FIG. 24. [Figure 38] FIG. 25 is a diagram showing the seventh step in FIG. 24. [Figure 39] 10 is a cross-sectional view showing a configuration of a surface-emitting laser according to a first modified example of the second embodiment of the present technology. FIG. [Figure 40] FIG. 10 is a cross-sectional view showing a configuration of a surface-emitting laser according to a second modification of the second embodiment of the present technology. [Figure 41] FIG. 10 is a cross-sectional view showing a configuration of a surface-emitting laser according to a third modification of the second embodiment of the present technology. [Figure 42]FIG. 10 is a cross-sectional view showing a configuration of a surface-emitting laser according to a fourth modified example of the second embodiment of the present technology. [Figure 43] 1 is a plan view showing a configuration example of a surface-emitting laser to which the present technology can be applied. [Figure 44] Fig. 44A is a cross-sectional view taken along line XX in Fig. 43. Fig. 44B is a cross-sectional view taken along line YY in Fig. 43. [Figure 45] 1A to 1C are diagrams illustrating examples of application of surface-emitting lasers according to embodiments and modifications of the present technology to distance measurement devices. [Figure 46] 1 is a block diagram showing an example of a schematic configuration of a vehicle control system; [Figure 47] FIG. 2 is an explanatory diagram showing an example of an installation position of a distance measurement device. DETAILED DESCRIPTION OF THE INVENTION

[0008] Preferred embodiments of the present technology will be described in detail below with reference to the accompanying drawings. Note that in this specification and the drawings, components having substantially the same functional configurations are denoted by the same reference numerals, and redundant description will be omitted. The embodiments described below illustrate typical embodiments of the present technology, and the scope of the present technology should not be interpreted as being narrow. Even when it is stated in this specification that the surface-emitting laser, electronic device, and method for manufacturing a surface-emitting laser according to the present technology achieve multiple effects, it is sufficient that the surface-emitting laser, electronic device, and method for manufacturing a surface-emitting laser according to the present technology achieve at least one effect. The effects described in this specification are merely examples and are not limiting, and other effects may also be achieved.

[0009] The explanation will be given in the following order: 1. Surface-emitting laser according to the first embodiment of the present technology (1) Structure of surface-emitting laser (2) Operation of surface-emitting lasers (3) Manufacturing method of surface-emitting laser (4) Effects of the surface-emitting laser and its manufacturing method 2. Surface-emitting lasers according to first to fifth modifications of the first embodiment of the present technology 3. Surface-emitting laser according to the second embodiment of the present technology (1) Structure of surface-emitting laser (2) Operation of surface-emitting lasers (3) Manufacturing method of surface-emitting laser (4) Effect of surface-emitting lasers 4. Surface-emitting lasers according to first to fourth modifications of the second embodiment of the present technology 5. Example of a surface-emitting laser configuration to which this technology can be applied 6. Modifications of this technology 7. Application examples to electronic devices 8. Example of applying a surface-emitting laser to a distance measurement device 9. Example of distance measurement device mounted on a moving object

[0010] 1. Surface-emitting laser according to the first embodiment of the present technology (1) Structure of surface-emitting laser 1 is a cross-sectional view showing a configuration of a surface-emitting laser 100 according to a first embodiment of the present technology. For convenience, the following description will refer to the upper side of the cross-sectional view of FIG. 1 and the like as the top and the bottom side as the bottom.

[0011] As an example, as shown in FIG. 1, the surface-emitting laser 100 includes first and second multilayer film reflectors 102 and 112, a plurality of (e.g., two) active layers (e.g., first and second active layers 104-1 and 104-2), a tunnel junction 108, and an oxide constriction layer 106.

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

[0013] As an example, the first and second multilayer reflectors 102 and 112 are stacked on top of each other on a substrate 101. Here, the second multilayer reflector 112 is disposed above the first multilayer reflector 102. The first and second active layers 104-1 and 104-2 are stacked between the first and second multilayer reflectors 102 and 112. The tunnel junction 108 is disposed between first and second active layers 104-1 and 104-2, which are two active layers adjacent to each other in the stacking direction (vertical direction) among the plurality of active layers. As an example, the oxidized constriction layer 106 is disposed between the tunnel junction 108 and the first active layer 104-1, which is one of the first and second active layers 104-1 and 104-2, which are two active layers adjacent to each other in the stacking direction.

[0014] In the surface-emitting laser 100, as an example, a first multilayer reflector 102, a first active layer 104-1, an oxide constriction layer 106, a tunnel junction 108, a second active layer 104-2, and a second multilayer reflector 112 are stacked on a substrate 101 in this order from the substrate 101 side (bottom side).

[0015] Here, a resonator R is configured including the first and second active layers 104-1 and 104-2, the tunnel junction 108, and the oxide constriction layer 106. That is, the surface-emitting laser 100 has a resonator structure in which the resonator R is disposed between the first and second multilayer film reflectors 102 and 112.

[0016] On the substrate 101, for example, a mesa M1 is formed, which includes a portion (upper portion) of the first multilayer reflector 102, first and second active layers 104-1 and 104-2, a tunnel junction 108, an oxide constriction layer 106, and a second multilayer reflector 112. The mesa M1 forms a resonator structure (excluding the other portion (lower portion) of the first multilayer reflector 102). The height direction of the mesa M1 approximately coincides with the stacking direction. The mesa M1 has, for example, a substantially cylindrical shape, but may have other shapes, such as a substantially elliptical cylinder shape, a substantially rectangular pillar shape, a substantially truncated pyramid shape, a substantially truncated circular cone shape, or a substantially truncated elliptical cone shape.

[0017] For example, the surface-emitting laser 100 emits light from an emission surface ES at the top of the mesa M1. That is, for example, the surface-emitting laser 100 is a surface-emitting surface-emitting laser.

[0018] The first active layer 104-1 is disposed at a position farther from the emission surface ES of the surface-emitting laser 100 than the other active layer 104-2 of the two adjacent active layers.

[0019] The first active layer 104-1 is disposed at a position closer to the first multilayer reflector 102, which is the other of the first and second multilayer reflectors 102, 112 that is closer to the output surface ES, than the second multilayer reflector 112, which is the other of the first and second multilayer reflectors 102, 112 that is closer to the output surface ES. The first active layer 104-1 is disposed, for example, in the lower half of the resonator R. More specifically, the first active layer 104-1 is disposed, for example, near the downstream end of the current path in the resonator R.

[0020] The second active layer 104-2 is disposed at a position closer to the second multilayer reflector 112 than to the first multilayer reflector 102. The second active layer 104-2 is disposed, for example, in the upper half of the resonator R. More specifically, the second active layer 104-2 is disposed, for example, near the upstream end of the current path in the resonator R.

[0021] The oxidized constricting layer 106 is disposed at a position closer to the first multilayer reflector 102 than to the second multilayer reflector 112. That is, the oxidized constricting layer 106 is disposed in the lower half of the resonator R, for example.

[0022] [substrate] The substrate 101 is, for example, a semiconductor substrate (for example, a GaAs substrate) of a first conductivity type (for example, n-type). A cathode electrode 117, which is an n-side electrode, is provided on the rear surface (lower surface) of the substrate 101.

[0023] The cathode electrode 117 may have a single layer structure or a multilayer structure. The cathode electrode 117 is made of, for example, AuGe / Ni / Au.

[0024] [First multilayer reflector] The first multilayer reflecting mirror 102 is disposed on a substrate 101, for example. The first multilayer reflector 102 is, for example, a semiconductor multilayer reflector. A multilayer reflector is also called a distributed Bragg reflector. A semiconductor multilayer reflector, which is a type of multilayer reflector (distributed Bragg reflector), has low light absorption, high reflectivity, and electrical conductivity. More specifically, the first multilayer reflector 102 is, for example, a semiconductor multilayer reflector of a 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 ¼ wavelength of the oscillation wavelength. Each refractive index layer of the first multilayer reflector 102 is made of an AlGaAs-based compound semiconductor of the first conductivity type (e.g., n-type).

[0025] [1st active layer] The first active layer 104-1 is disposed on the first multilayer reflector 102 via a first cladding layer 103 made of, for example, an undoped AlGaAs-based compound semiconductor. The "cladding layer" is also called a "spacer layer." The first active layer 104-1 is, for example, a non-doped InGaAs-based compound semiconductor (e.g., In 0.10 The active region is made of GaAs and the non-doped AlGaAs compound semiconductor (e.g., Al 0.1 The first active layer 104 has a layered structure in which guide and barrier regions made of GaAs (where the guide regions are at both ends in the stacking direction and the barrier region is in the middle in the stacking direction) are alternately stacked. Here, the first active layer 104 has, for example, two guide regions, two barrier regions, and three active 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 in the stacking direction is, for example, 8 nm. The surface-emitting laser 100 can perform laser oscillation with an oscillation wavelength in the 900 nm band, for example, because the first active layer 104-1 has this laminated structure.

[0026] [Oxidized constriction layer] The oxide constriction layer 106 is disposed on the first active layer 104-1 via a spacer layer 105 made of, for example, an undoped AlGaAs-based compound semiconductor. The spacer layer is also called a "cladding layer." The oxidized constriction layer 106 has, for example, a non-oxidized region 106a made of an AlGaAs-based compound semiconductor (e.g., AlGaAs, AlAs, etc.) and an oxidized region 106b surrounding the non-oxidized region 106a made of an oxide of the AlGaAs-based compound semiconductor (e.g., Al2O3). The base material of the oxidized constriction layer 106 (selectively oxidized layer 106S, described later) is preferably an AlGaAs film with an Al composition of 90% or more. If the oscillation wavelength of the surface-emitting laser 100 is λ, the first active layer 104-1, the tunnel junction 108, and the oxide constriction layer 106 are arranged within an optical thickness of 3λ / 4. The oxide confinement layer is also called a "current confinement layer."

[0027] [Tunnel Junction] The tunnel junction 108 is disposed on the oxidized constriction layer 106 via a spacer layer 107 made of, for example, a non-doped AlGaAs-based compound semiconductor. The tunnel junction 108 includes a p-type semiconductor layer 108a and an n-type semiconductor layer 108b stacked on top of each other. As an example, the p-type semiconductor layer 108a is disposed on the substrate 101 side (below) of the n-type semiconductor layer 108b. More specifically, as an example, the p-type semiconductor layer 108a is disposed between the oxidized constriction layer 106 and the n-type semiconductor layer 108b so as to be in contact with the n-type semiconductor layer 108b.

[0028] (p-type semiconductor layer) The p-type semiconductor layer 108a is made of, for example, a GaAs-based compound semiconductor, an AlGaAs-based compound semiconductor, an InGaAs-based compound semiconductor, or an AlGaInP-based compound semiconductor, which have a high carrier concentration. As a dopant material for the p-type semiconductor layer 108a, for example, C, Zn, Mg, etc. can be used. For example, the p-type semiconductor layer 108a may be made of a material containing a high concentration of C (carbon) (for example, 1×10 20 cm -3A 10 nm thick GaAs layer doped with ZnO can be used.

[0029] (n-type semiconductor layer) The n-type semiconductor layer 107b is made of, for example, a high-carrier-concentration n-type GaAs-based compound semiconductor, an AlGaAs-based compound semiconductor, an InGaAs-based compound semiconductor, or an AlGaInP-based compound semiconductor. The dopant material of the n-type semiconductor layer 108b may be Si, Te, Se, or the like. The n-type semiconductor layer 108b may be made of, for example, a high-concentration Si (silicon) (for example, 5×10 19 cm -3 A 20 nm thick GaAs layer doped with ZnO can be used.

[0030] [Second active layer] The second active layer 104-2 is disposed on the tunnel junction 108 via a spacer layer 109 made of, for example, an undoped AlGaAs-based compound semiconductor. The second active layer 104-2 has, for example, the same layer structure as the first active layer 104-1. That is, the second active layer 104-2 is, for example, a non-doped InGaAs-based compound semiconductor (e.g., In 0.10 The active region is made of GaAs and the non-doped AlGaAs compound semiconductor (e.g., Al 0.10 The second active layer 104-2 has a layered structure in which guide and barrier regions made of GaAs (where the guide regions are at both ends in the stacking direction and the barrier region is in the middle in the stacking direction) are alternately stacked. Here, the second active layer 104-2 has, for example, two guide regions, two barrier regions, and three active 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 in the stacking direction is, for example, 8 nm. The surface-emitting laser 100 can perform laser oscillation with an oscillation wavelength in the 900 nm band, for example, because the second active layer 104-2 has this stacked structure.

[0031] [Second multilayer reflector] The second multilayer reflector 112 is disposed on the second active layer 104-2 via a second cladding layer 111 made of, for example, an undoped AlGaAs-based compound semiconductor. The second multilayer reflector 112 is, for example, a semiconductor multilayer reflector. A multilayer reflector is also called a distributed Bragg reflector. A semiconductor multilayer reflector, which is a type of multilayer reflector (distributed Bragg reflector), has low light absorption, high reflectivity, and electrical conductivity. More specifically, the second multilayer reflector 112 is, for example, a semiconductor multilayer reflector of a second conductivity type (for example, p-type) and has a structure in which multiple types (for example, two types) of semiconductor layers with different refractive indices are alternately stacked with an optical thickness of ¼ wavelength of the oscillation wavelength. Each refractive index layer of the second multilayer reflector 112 is made of an AlGaAs-based compound semiconductor of the second conductivity type (for example, p-type). For example, the second multilayer reflector 112 is set to have a reflectance slightly lower than that of the first multilayer reflector 102.

[0032] Another oxidized constriction layer, an oxidized constriction layer 113, is disposed inside the second multilayer reflector 112. As an example, the second multilayer reflector 112 is the one of the first and second multilayer reflectors 102, 112 that is closer to the emission surface ES of the surface-emitting laser 100. As an example, the oxidized constriction layer 113 has a non-oxidized region 113a made of an AlGaAs-based compound semiconductor (e.g., AlGaAs, AlAs, etc.) of a second conductivity type (e.g., n-type) and an oxidized region 113b surrounding the non-oxidized region 113a made of an oxide of the AlGaAs-based compound semiconductor (e.g., Al2O3). As the base material of the oxidized constriction layer 113 (selectively oxidized layer 113S described below), an AlGaAs film with an Al composition of 90% or more is preferably used.

[0033] As described above, the oxidized constriction layers 106 and 113 are formed by selectively oxidizing a selectively oxidized layer made of an AlGaAs-based compound semiconductor, for example. The oxidized constriction layers 106 and 113 preferably have different Al compositions and / or optical thicknesses. This is because the oxidation states of the substrate (selectively oxidized layer) in the resonator R, including the oxidized constriction layer 106, and the second multilayer reflector 112, including the oxidized constriction layer 113, differ in the same oxidizing atmosphere. Therefore, to obtain the desired oxidized constriction diameter in each oxidized constriction layer, it is necessary to individually set the oxidation rates. The oxidized constriction diameters of the oxidized constriction layers 106 and 113 may be the same or different. The oxidation rate of the selectively oxidized layer tends to increase as the Al composition increases, and the oxidation rate also tends to increase as the optical thickness increases.

[0034] As an example, a contact layer 114 made of a GaAs layer of a second conductivity type (e.g., p-type) is disposed on the second multilayer reflector 112. Here, as an example, the contact layer 114 forms the top of the mesa M1, and the central part of the upper surface of the contact layer 114 (excluding the peripheral part) forms the emission surface ES.

[0035] The mesa M1 is covered with an insulating film 115 except for the central portion of the upper surface of the contact layer 114. The insulating film 115 is made of a dielectric material such as SiO2, SiN, or SiON. That is, a contact hole 115a is formed in the insulating film 115 on the top of the mesa M1 (e.g., the contact layer 114), and a ring-shaped anode electrode 116, which is a p-side electrode, is provided in the contact hole 115a so as to be in contact with the top of the mesa M1 (e.g., the contact layer 114). As an example, the anode electrode 116 is disposed in the contact hole 115a so that its center, as viewed from the stacking direction, substantially coincides with the center of the oxidized constriction layer 113. The inside of the anode electrode 116 serves as an emission port for laser light. The anode electrode 116 may have a single layer structure or a multilayer structure. The anode electrode 116 is made of, for example, Ti / Pt / Au.

[0036] (2) Operation of surface-emitting lasers 1, when a voltage is applied between the anode electrode 116 and the cathode electrode 117 and a current flows from the anode electrode 116 into the resonator structure including the mesa M1, the current is constricted by the oxide constriction layer 113 and injected into the second active layer 104-2, and a current having substantially the same value as the injected current is constricted by the oxide constriction layer 106 and injected into the first active layer 104-1 due to the tunnel effect of the tunnel junction 108. As a result, the first and second active layers 104-1, 104-2 emit light with substantially the same emission intensity, and the light travels back and forth between the first and second multilayer film reflectors 102, 112 while being amplified in each active layer, and when the oscillation conditions are satisfied, the light is emitted as laser light from the top of the mesa M1.

[0037] (3) Manufacturing method of surface-emitting laser A manufacturing method for the surface-emitting laser 100 will be described below with reference to the flowchart (steps S1 to S7) in FIG. 2. FIG. 2 shows a procedure that can be used to manufacture not only the surface-emitting laser 100 but also derivatives of the surface-emitting laser 100. Here, as an example, a semiconductor manufacturing method using semiconductor manufacturing equipment is used to simultaneously produce a plurality of surface-emitting laser arrays, each of which has a plurality of surface-emitting lasers 100 arranged two-dimensionally, on a single wafer, which is the base material of the substrate 101. Next, the plurality of surface-emitting laser arrays are separated by dicing to obtain a plurality of chip-shaped surface-emitting laser arrays (surface-emitting laser array chips). Note that the manufacturing method described below can also be used to simultaneously produce a plurality of surface-emitting lasers 100 on a single wafer, which is the base material of the substrate 101, and then separate the plurality of surface-emitting lasers 100 by dicing to obtain chip-shaped surface-emitting lasers (surface-emitting laser chips). The following series of steps is executed by a CPU of the semiconductor manufacturing equipment.

[0038] <Step S1: Laminated Body Generation Process 1> In the first step S1, a stacked body generation process 1 is performed. In the stacked body generation process 1, as an example, the layers constituting the surface-emitting laser 100 are sequentially stacked in a growth chamber by chemical vapor deposition (CVD), such as metalorganic chemical vapor deposition (MOCVD), to generate a stacked body L1 (see FIG. 11 ). Specifically, as described in detail below, for example, a structure including a stacked structure in which a first active layer 104-1, a selectively oxidized layer 106S, a tunnel junction 108, and a second active layer 104-2 are stacked in this order is stacked on the first multilayer reflector 102, and a second multilayer reflector 112 including a selectively oxidized layer 113S therein is stacked on the structure to generate the stacked body L1.

[0039] The laminate generation process 1 (step S1 in FIG. 2) will be described below with reference to the flowchart in FIG.

[0040] (Step S1-1) In step S1-1, the first multilayer film reflector 102 is laminated on the substrate 101 (see FIG. 4).

[0041] (Step S1-2: Resonator substrate production process 1) Step S1-2 performs a resonator substrate production process 1. The resonator substrate production process 1 is a process for producing a resonator substrate that will become the resonator R on the first multilayer film reflector 102, as will be described in detail below. The resonator substrate producing step 1 will be described below with reference to the flowchart of FIG. 5 and FIGS. 6 to 10 (first to fifth lamination process diagrams).

[0042] In step S1-2-1, a first active layer 104-1 is laminated on the first multilayer reflector 102 (see FIG. 6). More specifically, the first active layer 104-1 is laminated on the first multilayer reflector 102 with the first cladding layer 103 interposed therebetween.

[0043] In step S1-2-2, n is set to 1.

[0044] In step S1-2-3, a selected oxidation layer 106S-n is laminated on the n-th active layer 104-n (see FIG. 7). More specifically, the selected oxidation layer 106S-n is laminated on the first active layer 104-1 via a spacer layer 105. Here, the first selected oxidation layer 106S-1 is the selected oxidation layer 106S shown in FIG. 7.

[0045] In step S1-2-4, an n-th tunnel junction 108-n is laminated on the n-th selected oxidation layer 106S-n (see FIG. 8). More specifically, a p-type semiconductor layer 108a and an n-type semiconductor layer 108b that constitute the n-th tunnel junction 108-n are laminated in this order on the n-th selected oxidation layer 106S via a spacer layer 107.

[0046] In step S1-2-5, an (n + 1)-th active layer 104-(n + 1) is laminated on the n-th tunnel junction 108-n (see FIG. 9). More specifically, the (n + 1)-th active layer 104-(n + 1) is laminated on the n-th tunnel junction 108-n via a spacer layer 109.

[0047] In step S1-2-6, it is determined whether n < N. If the determination here is affirmative, the process proceeds to step S1-2-7, and if it is negative, the process proceeds to step S1-2-8. Here, N means the number of oxidized constriction layers in the resonator. In the case of the surface-emitting laser 100, since the number of oxidized constriction layers in the resonator is one and N = 1, when n = 1, the determination in step S1-2-6 is negative and the process proceeds to step S1-2-8.

[0048] In step S1-2-7, n is incremented. When step S1-2-7 is executed, the process returns to step S1-2-3, and a series of processes from S1-2-3 to S1-2-5 are executed again. Thereby, a resonator substrate for manufacturing a derivative system of the surface-emitting laser 100 can be generated by laminating a selected oxidation layer, a tunnel junction, and an active layer in this order on the second active layer 104-2.

[0049] In step S1-2-8, a second cladding layer 111 is laminated on the (n+1)th active layer 104-(n+1) (see FIG. 10), thereby producing a resonator substrate that will become a resonator.

[0050] (Step S1-3) In step S1-3, a second multilayer reflector 112 is laminated on the resonator substrate (see FIG. 11). More specifically, the second multilayer reflector 112, which includes a selectively oxidized layer 113S therein, and the contact layer 114 are laminated in this order on the second cladding layer 111 of the resonator substrate. As a result, a laminate (e.g., laminate L1) is produced. When step S1-3 is executed, laminate production process 1 is completed.

[0051] <Step S2> In step S2, the stack (for example, the stack L1) is etched to form a mesa (for example, the mesa M1) (see FIG. 12). Specifically, for example, a resist pattern is formed by photolithography on the laminate L1 removed from the growth chamber. Next, using this resist pattern as a mask, the laminate L1 is etched by, for example, RIE (reactive ion etching) until at least the side surface of the selectively oxidized layer 106S is exposed, thereby forming the mesa M1. As an example, the etching here is performed until the side surface of the first cladding layer 103 is completely exposed (for example, until the etched bottom surface is located within the first multilayer film reflector 102). Thereafter, the resist pattern is removed.

[0052] <Step S3> In step S3, the peripheral portions of the selectively oxidized layers 106S, 113S (see FIG. 12) are oxidized to form oxidized constriction layers 106, 113 (see FIG. 13). Specifically, for example, the mesa M1 is exposed to a water vapor atmosphere, and the selectively oxidized layers 106S and 113S are oxidized (selectively oxidized) from the side, forming an oxidized constriction layer 106 in which the non-oxidized region 106a is surrounded by the oxidized region 106b, and forming an oxidized constriction layer 113 in which the oxidized region 113a is surrounded by the oxidized region 113b.

[0053] <Step S4> In step S4, the insulating film 115 is formed (see FIG. 14). Specifically, for example, the insulating film 115 is formed over substantially the entire area of the stacked body in which the mesa M1 is formed.

[0054] <Step S5> In step S5, a contact hole 115a is formed (see FIG. 15). Specifically, for example, 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. Thereafter, the resist pattern is removed. As a result, the contact hole 115a is formed, and the contact layer 114 is exposed.

[0055] <Step S6> In step S6, the anode electrode 116 is formed (see FIG. 16). Specifically, for example, a Ti / Pt / Au film is formed on the contact layer 114 through the contact hole 115a by, for example, EB evaporation, and the resist and the Ti / Pt / Au film on the resist are lifted off to form the ring-shaped anode electrode 116 in the contact hole 115a.

[0056] <Step S7> In step S7, the cathode electrode 117 is formed (see FIG. 17). Specifically, after polishing the rear surface (lower surface) of the substrate 101, for example, an AuGe / Ni / Au film is formed on the rear surface. When step S7 is performed, the flow in FIG. 2 ends.

[0057] (4) Effects of the surface-emitting laser and its manufacturing method The surface-emitting laser 100 according to the first embodiment of the present technology is a surface-emitting laser including first and second multilayer reflectors 102, 112, a plurality of active layers (e.g., first and second active layers 104-1, 104-2) stacked between the first and second multilayer reflectors 102, 112, a tunnel junction 108 arranged between the first and second active layers 104-1, 104-2, which are two active layers adjacent to each other in the stacking direction among the plurality of active layers, and an oxide constriction layer 106 arranged between the tunnel junction 108 and the first active layer 104-1, which is one of the two adjacent active layers. In this case, for example, a current injected into the second active layer 104-2 and passing through the tunnel junction 108 is confined by the oxide constriction layer 106 and then injected into the first active layer 104-1. This allows the current to be efficiently injected into the first active layer 104-1, and prevents a decrease in the light-emitting efficiency of the first active layer 104-1. As a result, the surface-emitting laser 100 of the first embodiment can provide a surface-emitting laser that can suppress a decrease in light-emitting efficiency.

[0058] Furthermore, in the surface-emitting laser 100, when the light generated in each of the first and second active layers 104-1 and 104-2 travels back and forth between the first and second multilayer film reflectors 102 and 112, the light confinement effect is increased by the oxidized confinement layer 106, so that the control range of the emission angle of the laser light (emitted light) can also be expanded.

[0059] The first active layer 104-1, which is one of the active layers (the active layer sandwiching the oxide constriction layer 106 with the tunnel junction 108), is disposed at a position farther from the emission surface ES of the surface-emitting laser 100 than the second active layer 104-2, which is the other active layer of the two adjacent active layers. This allows the oxide constriction layer 106 to be disposed at a position farther from the emission surface ES (at least farther from the emission surface ES than the tunnel junction 108), thereby achieving a current constriction effect at that position. That is, it is possible to constrict the current injected into the first active layer 104-1, which is disposed at a position farther from the emission surface ES (at least farther from the emission surface ES than the oxide constriction layer 106) in the resonator R provided between the first and second multilayer film reflectors 102, 112, and this improves the efficiency of current injection into the first active layer 104-1. If the oxide constriction layer 106 were not provided in the resonator, the current supplied to the resonator from the emission surface ES would spread within the resonator and be injected into the second active layer 104-2 and the first active layer 104-1, in that order. In this case, the first active layer 104-1 is located closer to the downstream end of the current path within the resonator than the second active layer 104-2, resulting in a more spread-out current being injected. In other words, the first active layer 104-1 is in a less favorable position in terms of current injection efficiency than the second active layer 104-2. Therefore, being able to constrict the current injected into the first active layer 104-1 is very significant.

[0060] The first active layer 104-1, which is one of the active layers (the active layer sandwiching the oxide constriction layer 106 with the tunnel junction 108), is disposed at a position (for example, in the lower half of the resonator R) closer to the first multilayer reflector 102, which is the other of the first and second multilayer reflectors 102, 112, that is farther from the exit surface ES than the second multilayer reflector 112, which is the other of the first and second multilayer reflectors 102, 112 that is closer to the exit surface ES. This allows the oxide constriction layer 106 to effectively constrict the current injected into the first active layer 104-1, which is disposed in the lower half of the resonator R, for example. The first active layer 104-1, which is one of the active layers (the active layer sandwiching the oxide constriction layer 106 with the tunnel junction 108), may be disposed at a position (e.g., in the upper half of the resonator R) closer to the second multilayer reflector 112, which is closer to the output surface ES, than the first multilayer reflector 102, which is one of the first and second multilayer reflectors 102, 112, which is farther from the output surface ES. In this case, the oxide constriction layer 106, the tunnel junction 108, and the second active layer 104-2 may also be disposed at a position (e.g., in the upper half of the resonator R) closer to the second multilayer reflector 112 than the first multilayer reflector 102.

[0061] An oxide constriction layer 113 (another oxide constriction layer) is disposed inside one of the first and second multilayer film reflectors 102, 112 that is closer to the emission surface ES of the surface-emitting laser 100. This makes it possible to effectively constrict the current injected into the second active layer 104-2, which is disposed at a position closer to the emission surface ES (for example, in the upper half of the resonator R (more specifically, for example, near the upstream end of the current path in the resonator R)) of the first and second active layers 104-1, 104-2.

[0062] Preferably, the oxidized confinement layers 106 and 113 are both formed by selectively oxidizing a layer made of an AlGaAs-based compound semiconductor.

[0063] The oxidized constriction layers 106 and 113 have different Al compositions and / or optical thicknesses, which allows the oxidized constriction diameters of the oxidized constriction layers 106 and 113 to be set to desired sizes when selective oxidation treatment is performed in the same oxidizing atmosphere (for example, the same water vapor atmosphere).

[0064] The tunnel junction 108 has a layer structure in which a p-type semiconductor layer 108a and an n-type semiconductor layer 108b are stacked on top of each other, and the oxidized constriction layer 106 is disposed on the p-type semiconductor layer 108a side, which allows the oxidized constriction layer 106 to be disposed at a position closer to the first multilayer film reflector 102, which is an n-type multilayer film reflector (at a position farther from the emission surface ES).

[0065] If the oscillation wavelength of the surface-emitting laser 100 is λ, the first active layer 104-1, the tunnel junction 108, and the oxide constriction layer 106 are arranged within an optical thickness of 3λ / 4. In this case, for example, in the resonator, the first active layer 104-1 can be arranged at or near an antinode of a standing wave of wavelength λ, and the tunnel junction 108 and the oxide constriction layer 106 can be arranged at or near a node of the standing wave. This makes it possible to minimize attenuation of the standing wave, and ultimately to suppress a decrease in the output power of the surface-emitting laser 100.

[0066] The method for manufacturing the surface-emitting laser 100 includes the steps of: stacking a structure including a stacked structure in which a first active layer 104-1, a selectively oxidized layer 106S, a tunnel junction 108, and a second active layer 104-2 are stacked in this order on a first multilayer reflector 102; stacking at least a second multilayer reflector 112 on the structure to generate a stack L1; etching the stack L1 until at least the side surface of the selectively oxidized layer 106S is exposed to form a mesa M1; and selectively oxidizing the selectively oxidized layer 106S from the side surface to form an oxidized constriction layer 106. This makes it possible to manufacture a refractive index guided surface emitting laser 100 that can suppress a decrease in light emission efficiency.

[0067] 2. Surface-emitting lasers according to first to fifth modifications of the first embodiment of the present technology Surface-emitting lasers according to first to fifth modifications of the first embodiment of the present technology will be described below.

[0068] (Variation 1)

[0069] As shown in FIG. 18, the surface-emitting laser 100-1 of the first modification has a configuration similar to that of the surface-emitting laser 100 of the first embodiment (see FIG. 1), except that an oxidized constriction layer 106 (referred to as the second oxidized constriction layer 106-2) is provided between the second active layer 104-2 and the tunnel junction 108, another oxidized constriction layer 106 (referred to as the first oxidized constriction layer 106-1) is provided between the first multilayer film reflector 102 and the first active layer 104-1 instead of the oxidized constriction layer 113, and the conductivity types are reversed. In the surface-emitting laser 100-4, the conductivity type of the first multilayer reflector 102 is p-type, the conductivity type of the second multilayer reflector 112 is n-type, the anode electrode 116 is disposed on the back side of the substrate 101, the cathode electrode 117 is disposed on the top of the mesa, and in the tunnel junction 108, the n-type semiconductor layer 108b is disposed on the substrate 101 side of the p-type semiconductor layer 108a. In the surface-emitting laser 100-1, the second active layer 104-2, which is an active layer sandwiching the second oxide constriction layer 106-2 with the tunnel junction 108, is disposed at a position closer to the emission surface ES of the surface-emitting laser 100 than the first active layer 104-1. This allows the second oxide constriction layer 106-2 to be disposed at a position closer to the emission surface ES (at least closer to the emission surface ES than the tunnel junction 108), thereby achieving a current constriction effect at that position. That is, a current constriction effect can be achieved at a position closer to the emission surface ES (at least closer to the emission surface ES than the oxide constriction layer 106, for example, in the upper half of the cavity) in the cavity provided between the first and second multilayer film reflectors 102, 112, thereby improving the efficiency of current injection into the second active layer 104-2.

[0070] In the surface-emitting laser 100-1, the second active layer 104-2, which is an active layer sandwiching the second oxide constriction layer 106-2 with the tunnel junction 108, is positioned closer to the second multilayer reflector 112, which is the other multilayer reflector closer to the emission surface ES, than to the first multilayer reflector 102, which is one of the first and second multilayer reflectors 102, 112 and farther from the emission surface ES. In the surface-emitting laser 100-1, a current flowing in from the anode electrode 116 passes through the substrate 101 and the first multilayer reflector 102, is confined by the first oxide constriction layer 106-1, and is then injected into the first active layer 104-2. The current passing through the first active layer 104-1 passes through the tunnel junction 108, is confined by the oxide constriction layer 106-2, and is then injected into the second active layer 104-2. This allows current to be efficiently injected into each active layer. The second active layer 104-2, which is an active layer sandwiching the oxide constriction layer 106-2 with the tunnel junction 108, may be disposed at a position (for example, in the lower half of the resonator) closer to the first multilayer reflector 102, which is the other of the first and second multilayer reflectors 102, 112, that is farther from the output surface ES than the second multilayer reflector 112, which is the other of the first and second multilayer reflectors 102, 112 that is closer to the output surface ES. In this case, the oxide constriction layer 106, the tunnel junction 108, and the first active layer 104-1 may also be disposed at a position (for example, in the lower half of the resonator) closer to the first multilayer reflector 102 than the second multilayer reflector 112. The surface-emitting laser 100-1 of the first modification can be manufactured by a manufacturing method similar to that of the surface-emitting laser 100 of the first embodiment (see FIG. 1), except that another oxidized constriction layer 106 is formed in place of the oxidized constriction layer 113 in the stack generation process and the stacking order is partially different.

[0071] (Variation 2) As shown in FIG. 19, the surface-emitting laser 100-3 of the second modification has a configuration similar to that of the surface-emitting laser 100 of the first embodiment (see FIG. 1), except that it has multiple (e.g., two) stacked structures between the first and second multilayer film reflectors 102, 112, in which an active layer, an oxide constriction layer, and a tunnel junction are stacked in this order from the first multilayer film reflector 102 side. More specifically, the surface-emitting laser 100-3 has a first stacked structure in which a first active layer 104-1, a first oxide constriction layer 106-1, and a first tunnel junction 108-1 are stacked in this order from the first multilayer reflector 102 side. Furthermore, the surface-emitting laser 100-3 has a second stacked structure on the first stacked structure in which a second active layer 104-2, a second oxide constriction layer 106-2, and a second tunnel junction 108-2 are stacked in this order from the first multilayer reflector 102 side. The first and second tunnel junctions 108-1 and 108-2 have substantially the same configuration and function as the tunnel junction 108. Furthermore, the surface-emitting laser 100-3 has a third active layer 104-3 on the second stacked structure.

[0072] That is, in the surface-emitting laser 100-3, the multiple active layers are three active layers (first to third active layers 104-1 to 104-3), and a first tunnel junction 108-1 is arranged between the first pair of adjacent active layers, the first and second active layers 104-1 and 104-2, of at least two pairs of adjacent active layers (first and second active layers 104-1 and 104-2, second and third active layers 104-2 and 104-3) among the multiple (e.g., three) active layers, and a second tunnel junction 108-2 is arranged between the second pair of adjacent active layers, the second and third active layers 104-2 and 104-3. Furthermore, a first oxide constriction layer 106-1 is disposed between a first active layer 104-1, which is one of the first and second active layers 104-1 and 104-2, which are two adjacent active layers in a first set, and a first tunnel junction 108-1 disposed between the two adjacent active layers. Furthermore, a second oxide constriction layer 106-2 is disposed between a second active layer 104-2, which is one of the second and third active layers 104-2 and 104-3, which are two adjacent active layers in a second set, and a second tunnel junction 108-2 disposed between the two adjacent active layers.

[0073] The surface-emitting laser 100-3 includes first, second, and third active layers 104-1 to 104-3, which are stacked in this order, with a first tunnel junction 108-1 disposed between the first and second active layers 104-1 and 104-2 and a second tunnel junction 108-2 disposed between the second and third active layers 104-2 and 104-3. Furthermore, a first oxide constriction layer 106-1 is disposed between the first active layer 104-1 and the first tunnel junction 108-1, and a second oxide constriction layer 106-2 is disposed between the second active layer 104-2 and the second tunnel junction 108-2.

[0074] In the surface-emitting laser 100-3, the first active layer 104-1 is the active layer that is arranged at the farthest position from the emission surface ES of the surface-emitting laser 100-3 (for example, near the downstream end of the current path in the resonator) among the three active layers 104-1 to 104-3.

[0075] According to the surface-emitting laser 100-3, even in the case of a multi-active layer structure with three active layers, current can be efficiently injected into each active layer, and a decrease in the light-emitting efficiency of the active layers can be suppressed. The surface-emitting laser 100-3 is a derivative of the surface-emitting laser 100, and can be manufactured by the procedure of the flowchart in FIG. 5 (however, N=2 in step S1-2-6).

[0076] (Variation 3) As shown in FIG. 20, the surface-emitting laser 100-4 of the third modification has a configuration similar to that of the surface-emitting laser 100-3 of the second modification (see FIG. 19), except that it has multiple (e.g., two) stacked structures between the first and second multilayer reflectors 102, 112, in which a tunnel junction, an oxide constriction layer, and an active layer are stacked in this order from the first multilayer reflector 102 side, that another oxide constriction layer 106 is provided between the first multilayer reflector 102 and the first active layer 104-1 instead of the oxide constriction layer 113, and that the conductivity types are opposite. That is, the surface-emitting laser 100-4 has a configuration similar to that of the surface-emitting laser 100-3 turned upside down. In the surface-emitting laser 100-4, the conductivity type of the first multilayer film reflector 102 is p-type, the conductivity type of the second multilayer film reflector 112 is n-type, the anode electrode 116 is disposed on the back surface side of the substrate 101, the cathode electrode 117 is disposed on the top of the mesa, and at each tunnel junction, the n-type semiconductor layer 108b (the gray layer in FIG. 20) is disposed on the substrate 101 side of the p-type semiconductor layer 108a. More specifically, the surface-emitting laser 100-4 has a first stacked structure in which a first tunnel junction 108-1, a first oxide constriction layer 106-1, and a second active layer 104-2 are stacked in this order from the first multilayer reflector 102 side. Furthermore, the surface-emitting laser 100-4 has a second stacked structure on the first stacked structure in which a second tunnel junction 108-2, a second oxide constriction layer 106-2, and a third active layer 104-3 are stacked in this order from the first multilayer reflector 102 side. Furthermore, the surface-emitting laser 100-4 has a first active layer 104-1 below the first stacked structure. According to the surface-emitting laser 100-4, even in the case of a multi-active layer structure with three active layers, current can be efficiently injected into each active layer, and a decrease in the light-emitting efficiency of the active layers can be suppressed. The surface-emitting laser 100-4 can be manufactured by a manufacturing method similar to that of the surface-emitting laser 100-3 of variant example 2 (see Figure 19), except that in the stack generation process, an oxidized constriction layer 106 is formed instead of the oxidized constriction layer 113 and the stacking order is different.

[0077] (Variation 4) As shown in FIG. 21, the surface-emitting laser 100-5 of the fourth modification has a configuration similar to that of the surface-emitting laser 100 of the first embodiment (see FIG. 1), except that it has multiple (e.g., three) stacked structures between the first and second multilayer film reflectors 102, 112, in which an active layer, an oxide constriction layer, and a tunnel junction are stacked in this order from the first multilayer film reflector 102 side. More specifically, the surface-emitting laser 100-5 has a first stacked structure in which a first active layer 104-1, a first oxide constriction layer 106-1, and a first tunnel junction 108-1 are stacked in this order from the first multilayer reflector 102 side. Furthermore, the surface-emitting laser 100-5 has a second stacked structure on the first stacked structure in which a second active layer 104-2, a second oxide constriction layer 106-2, and a second tunnel junction 108-2 are stacked in this order from the first multilayer reflector 102 side. Furthermore, the surface-emitting laser 100-5 has a third stacked structure on the second stacked structure in which a third active layer 104-3, a third oxide constriction layer 106-3, and a third tunnel junction 108-3 are stacked in this order from the first multilayer reflector 102 side. The third tunnel junction 108-3 has substantially the same configuration and function as the tunnel junction 108. Furthermore, the surface-emitting laser 100-5 has a fourth active layer 104-4 on the third stacked structure. According to the surface-emitting laser 100-5, even in the case of a multi-active layer having four active layers, it is possible to efficiently inject current into each active layer, thereby suppressing a decrease in the light-emitting efficiency of the active layers. Note that, according to a surface-emitting laser (a derivative of the surface-emitting laser 100) having four or more of the above-mentioned stacked structures and the oxide constriction layer 113, it is possible to efficiently inject current into each active layer, thereby suppressing a decrease in the light-emitting efficiency of the active layers, even in the case of a multi-active layer having five or more active layers. The surface-emitting laser 100-5 is a derivative of the surface-emitting laser 100, and can be manufactured by the procedure of the flowchart in Fig. 5 (however, N=3 in step S1-2-6). Note that a surface-emitting laser having four or more of the above-described stacked structures can be manufactured by a similar manufacturing method (however, N≧4 in step S1-2-6 in Fig. 5).

[0078] (Variation 5) 22, the surface-emitting laser 100-6 of the fifth modification has a configuration similar to that of the surface-emitting laser 100-5 of the fourth modification (see FIG. 21), except that it has a plurality of (e.g., three) stacked structures, each having a tunnel junction, an oxide constriction layer, and an active layer stacked in this order from the first multilayer reflector 102 side, between the first and second multilayer reflectors 102, 112, that another oxide constriction layer 106 is provided between the first multilayer reflector 102 and the first active layer 104-1 instead of the oxide constriction layer 113, and that the conductivity types are opposite. That is, the surface-emitting laser 100-6 has a configuration similar to that of the surface-emitting laser 100-5 turned upside down. In the surface-emitting laser 100-6, the conductivity type of the first multilayer reflector 102 is p-type, the conductivity type of the second multilayer reflector 112 is n-type, the anode electrode 116 is disposed on the back side of the substrate 101, the cathode electrode 117 is disposed on the top of the mesa, and at each tunnel junction, the n-type semiconductor layer 108b (gray layer in Figure 22) is disposed on the substrate 101 side of the p-type semiconductor layer 108a. More specifically, the surface-emitting laser 100-6 has a first stacked structure in which a first tunnel junction 108-1, a first oxide constriction layer 106-1, and a second active layer 104-2 are stacked in this order from the first multilayer reflector 102 side. Furthermore, the surface-emitting laser 100-6 has a second stacked structure on the first stacked structure in which a second tunnel junction 108-2, a second oxide constriction layer 106-2, and a third active layer 104-3 are stacked in this order from the first multilayer reflector 102 side. Furthermore, the surface-emitting laser 100-6 has a third stacked structure on the second stacked structure in which a third tunnel junction 108-3, a third oxide constriction layer 106-3, and a fourth active layer 104-4 are stacked in this order from the first multilayer reflector 102 side. Furthermore, the surface-emitting laser 100-6 has a first active layer 104-1 below the first stacked structure. According to the surface-emitting laser 100-6, even in the case of a multi-active layer having four active layers, it is possible to efficiently inject current into each active layer and suppress a decrease in the light-emitting efficiency of the active layers. Note that, according to a surface-emitting laser having four or more of the above-mentioned stacked structures and the oxide constriction layer 113, it is possible to efficiently inject current into each active layer and suppress a decrease in the light-emitting efficiency of the active layers even in the case of a multi-active layer having five or more active layers. The surface-emitting laser 100-6 can be manufactured by the same manufacturing method as the surface-emitting laser 100-4 (see FIG. 20) of Modification 3, except that in the stack generation process, another oxidized constriction layer 106 is formed instead of the oxidized constriction layer 113 and the number of stacking steps increases. Note that a surface-emitting laser having four or more of the above stack structures can be manufactured by the same manufacturing method.

[0079] 3. Surface-emitting laser according to the second embodiment of the present technology Hereinafter, a surface-emitting laser 200 according to a second embodiment of the present technology will be described. (1) Structure of surface-emitting laser 23, the surface-emitting laser 200 according to the second embodiment has the same configuration as the surface-emitting laser 100 according to the first embodiment (see FIG. 1), except that a second tunnel junction 108-2 and a third active layer 104-3 are stacked in this order on the second active layer 104-2. That is, the surface-emitting laser 200 has one pair of a tunnel junction and an active layer on the second active layer 104-2. From another perspective, the surface-emitting laser 200 differs from the surface-emitting laser 100-3 of Modification 2 (see FIG. 19) in that no oxide constriction layer is disposed between the second active layer 104-2 and the second tunnel junction 108-2.

[0080] (2) Operation of surface-emitting lasers In the surface-emitting laser 200 shown in FIG. 23, when a voltage is applied between the anode electrode 116 and the cathode electrode 117 and a current flows from the anode electrode 116 into the resonator structure including the mesa M2, the current is constricted by the oxidized constriction layer 113 and injected into the third active layer 104-3, a current having approximately the same value as the injected current is injected into the second active layer 104-2 due to the tunneling effect of the second tunnel junction 108-2, and a current having approximately the same value as the injected current is constricted by the oxidized constriction layer 106 and injected into the first active layer 104-1 due to the tunneling effect of the first tunnel junction 108-1. As a result, the first to third active layers 104-1, 104-2, and 104-3 emit light with approximately the same emission intensity, and the light travels back and forth between the first and second multilayer film reflectors 102 and 112 while being amplified in each active layer, and when the oscillation conditions are satisfied, it is emitted as laser light from the top of the mesa M2.

[0081] (3) Manufacturing method of surface-emitting laser A manufacturing method of the surface-emitting laser 200 will be described below with reference to the flowchart (steps S11 to S17) in FIG. 24. FIG. 24 shows a procedure that can manufacture not only the surface-emitting laser 200 but also surface-emitting lasers derived from the surface-emitting laser 200. Here, as an example, a semiconductor manufacturing method using semiconductor manufacturing equipment is used to simultaneously produce a plurality of surface-emitting laser arrays, each of which has a plurality of surface-emitting lasers 200 arranged two-dimensionally, on a single wafer, which is the base material of the substrate 101. Next, the plurality of surface-emitting laser arrays are separated by dicing to obtain a plurality of chip-shaped surface-emitting laser arrays (surface-emitting laser array chips). Note that the manufacturing method described below can also simultaneously produce a plurality of surface-emitting lasers 200 on a single wafer, which is the base material of the substrate 101, and then separate the plurality of surface-emitting lasers 200 by dicing to obtain chip-shaped surface-emitting lasers (surface-emitting laser chips). The following series of steps is executed by a CPU of the semiconductor manufacturing equipment.

[0082] <Step S11: Laminated Body Generation Process 2> In the first step S11, a stacked body generating process 2 is performed. In the stacked body generating process 2, as an example, the layers constituting the surface-emitting laser 200 are sequentially stacked in a growth chamber by chemical vapor deposition (CVD), such as metal-organic chemical vapor deposition (MOCVD), to generate a stacked body L2 (see FIG. 32). Specifically, when manufacturing the surface-emitting laser 200, as described in detail below, a structure including a stacked structure in which an active layer 104-1, a selectively oxidized layer 106S, a first tunnel junction 108-1, a second active layer 104-2, a second tunnel junction 108-2, and a third active layer 104-3 are stacked in this order from the first multilayer reflector 102 side is stacked on the first multilayer reflector 102, and a second multilayer reflector 112 including a selectively oxidized layer 113S therein is stacked on the structure to generate the stacked body L2 (see FIG. 32).

[0083] The laminate generation process 2 (step S11 in FIG. 24) will be described below with reference to the flowchart in FIG.

[0084] (Step S11-1) In step S11-1, the first multilayer film reflector 102 is laminated on the substrate 101 (see FIG. 4).

[0085] (Step S11-2: Resonator substrate production process 2) In step S11-2, a resonator substrate production process 2 is carried out. As will be described in detail below, the resonator substrate production process 2 is a process of producing a resonator substrate that becomes a resonator by stacking each layer that constitutes a resonator on the first multilayer film reflector 102. The resonator substrate producing step 2 will be described below with reference to the flowchart of FIG. 26, and FIGS. 6, 7, and 27 to 31 (first to seventh lamination process diagrams).

[0086] In the first step S11-2-1, a first active layer 104-1 is laminated on the first multilayer reflector 102 (see FIG. 6). More specifically, the first active layer 104-1 is laminated on the first multilayer reflector 102 with a first cladding layer 103 interposed therebetween.

[0087] In the next step S11-2-2, set 1 to n.

[0088] In the next step S11-2-3, stack the n-th selectively oxidized layer 106S-n on the n-th active layer 104-n (see Fig. 7). More specifically, stack the n-th selectively oxidized layer 106S-n on the first active layer 104-1 via the spacer layer 105. Here, the first selectively oxidized layer 106S-1 is the selectively oxidized layer 106S.

[0089] In the next step S11-2-4, stack the n-th tunnel junction 108-n on the n-th selectively oxidized layer 106S-n (see Fig. 27). Here, more specifically, stack the p-type semiconductor layer 108a and the n-type semiconductor layer 108b constituting the n-th tunnel junction 108-n in this order on the n-th selectively oxidized layer 106S via the spacer layer 107.

[0090] In the next step S11-2-5, stack the (n + 1)-th active layer 104-(n + 1) on the n-th tunnel junction 108-n (see Fig. 28). More specifically, stack the (n + 1)-th active layer 104-(n + 1) on the n-th tunnel junction 108-n via the spacer layer 109.

[0091] In the next step S11-2-6, determine whether n < N. If the determination here is affirmative, proceed to step S11-2-7; if negative, proceed to step S11-2-8. Here, N means the number of oxidized constriction layers in the resonator. In the case of the surface-emitting laser 200, since the number of oxidized constriction layers in the resonator is one, N = 1. When n = 1, the determination in step S11-2-6 is negative, and the process proceeds to step S11-2-8.

[0092] In step S11-2-7, n is incremented. When step S11-2-7 is executed, the process returns to step S11-2-3, and a series of processes from S11-2-3 to S11-2-5 are executed again. Thereby, a resonator substrate for manufacturing a derivative system of the surface-emitting laser 200 can be generated by further laminating a selected oxidation layer, a tunnel junction, and an active layer in this order on the second active layer 104-2.

[0093] In step S11-2-8, 1 is set to m.

[0094] In the next step S11-2-9, the (n + m)-th tunnel junction 108-(n + m) is laminated on the (n + m)-th active layer 104-(n + m) (see Fig. 29). More specifically, the (n + m)-th tunnel junction 108-(n + m) is laminated on the (n + m)-th active layer 104-(n + m) via a spacer layer 109.

[0095] In step S11-2-10, the (n + m + 1)-th active layer 104-(n + m + 1) is laminated on the (n + m)-th tunnel junction 108-(n + m) (see Fig. 30). More specifically, the (n + m + 1)-th active layer 104-(n + m + 1) is laminated on the (n + m)-th tunnel junction 108-(n + m) via a spacer layer 109.

[0096] In the next step S11-2-11, it is determined whether m < M. If the determination here is affirmative, the process proceeds to step S11-2-12; if negative, the process proceeds to step S11-2-13. Here, M means the number of pairs of tunnel junctions and active layers on the second active layer 104-2. In the surface-emitting laser 200, since the number of such pairs is one, M = 1. When m = 1, the determination in step S11-2-11 is negative, and the process proceeds to step S11-2-13.

[0097] In step S11-2-12, m is incremented. After step S11-2-12 is executed, the process returns to step S11-2-9, and the series of processes of S11-2-9 and S11-2-10 are executed again. This allows further pairs of tunnel junctions and active layers to be stacked on the second active layer 104-2, thereby generating a resonator substrate for manufacturing a derivative system of the surface-emitting laser 200.

[0098] In step S11-2-13, a second cladding layer 111 is laminated on the (n+m+1)th active layer 104-(n+m+1) (see FIG. 31). This produces a resonator substrate. When step S11-2-13 is performed, the flow of resonator substrate production process 2 shown in FIG. 26 ends. (Step S11-3) In step S11-3, the second multilayer reflector 112 is laminated on the resonator (see FIG. 32). More specifically, the second multilayer reflector 112 containing the selectively oxidized layer 113S therein and the contact layer 114 are laminated in this order on the cladding layer 111 of the resonator. As a result, a laminate (for example, laminate L2) is generated. When step S11-3 is executed, the flow of laminate generation process 2 shown in FIG. 25 is completed.

[0099] <Step S12> In step S12, the stack (for example, stack L2) is etched to form a mesa (for example, mesa M1) (see FIG. 33--). Specifically, for example, a resist pattern is formed by photolithography on the laminate L2 removed from the growth chamber. Next, using this resist pattern as a mask, the laminate L2 (see FIG. 32) is etched by, for example, RIE (reactive ion etching) until at least the side surface of the selectively oxidized layer 106S is exposed, thereby forming the mesa M2. As an example, the etching here is performed until the side surface of the first cladding layer 103 is completely exposed (for example, until the etched bottom surface is located within the first multilayer film reflector 102). Thereafter, the resist pattern is removed.

[0100] <Step S13> In step S13, for example, the peripheral portions of the selectively oxidized layers 106S, 113S (see FIG. 33) are oxidized to form oxidized constriction layers 106, 113 (see FIG. 34). Specifically, for example, the mesa M2 is exposed to a water vapor atmosphere, and the selectively oxidized layers 106S and 113S are oxidized (selectively oxidized) from the side, forming an oxidized constriction layer 106 in which the non-oxidized region 106a is surrounded by the oxidized region 106b, and forming an oxidized constriction layer 113 in which the oxidized region 113a is surrounded by the oxidized region 113b.

[0101] <Step S14> In step S14, the insulating film 115 is formed (see FIG. 35). Specifically, for example, the insulating film 115 is formed over substantially the entire area of the stacked body in which the mesa M2 is formed.

[0102] <Step S15> In step S15, a contact hole 115a is formed (see FIG. 36). Specifically, for example, 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. Next, 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. Thereafter, the resist pattern is removed. As a result, the contact hole 115a is formed, and the contact layer 114 is exposed.

[0103] <Step S16> In step S16, the anode electrode 116 is formed (see FIG. 37). Specifically, for example, a Ti / Pt / Au film is formed on the contact layer 114 through the contact hole 115a by, for example, EB evaporation, and the resist and the Ti / Pt / Au film on the resist are lifted off to form the ring-shaped anode electrode 116 in the contact hole 115a.

[0104] <Step S17> In step S17, the cathode electrode 117 is formed (see FIG. 38). Specifically, after the rear surface (lower surface) of the substrate 101 is polished, for example, an AuGe / Ni / Au film is formed on the rear surface. When step S17 is performed, the flow in FIG. 24 ends.

[0105] (4) Effect of surface-emitting lasers In the surface-emitting laser 200 of the second embodiment, even when the active layer has three multi-active layers and the cavity length is long, the oxide constriction layer 106 allows current to be efficiently injected into the first active layer 104-1, which is the active layer located near the downstream end of the current path in the cavity (for example, the active layer farthest from the emission surface ES).

[0106] 4. Surface-emitting lasers according to first to fourth modifications of the second embodiment of the present technology Surface-emitting lasers according to first to fourth modifications of the second embodiment of the present technology will be described below.

[0107] (Variation 1) As shown in FIG. 39, the surface-emitting laser 200-1 of the first modification has a configuration similar to that of the surface-emitting laser 200 of the second embodiment (FIG. 23), except that it has two pairs of tunnel junctions and active layers on the second active layer 104-2. The surface-emitting laser 200-1 has a configuration in which a third tunnel junction 108-3 and a fourth active layer 104-4 are stacked in this order on a third active layer 104-3 in the cavity of the surface-emitting laser 200. More specifically, in the surface-emitting laser 200-1, a third tunnel junction 108-3 is stacked on the third active layer 104-3 with a spacer layer 109 interposed therebetween, and a fourth active layer 104-4 is stacked on the third tunnel junction 108-3 with the spacer layer 109 interposed therebetween. In the surface-emitting laser 200-1 of the first modification, even when the active layer has four multi-active layers and the cavity length is long, the oxide constriction layer 106 allows current to be efficiently injected into the first active layer 104-1, which is the active layer located near the downstream end of the current path in the cavity (for example, the active layer farthest from the emission surface ES). The surface-emitting laser 200-1 is a derivative of the surface-emitting laser 200, and can be manufactured according to the procedure of the flowchart in FIG. 26 (where N=1 and M=2).

[0108] (Variation 2) As shown in FIG. 40, the surface-emitting laser 200-2 of the second modification has a configuration similar to that of the surface-emitting laser 200-1 of the first modification (see FIG. 39), except that a first oxide constriction layer 106-1 is provided between the first active layer 104-1 and the first tunnel junction 108-1, and a second oxide constriction layer 106-2 is provided between the second active layer 104-2 and the second tunnel junction 108-2. In the surface-emitting laser 200-2 of the second modification, even if the active layer has four multi-active layers and the cavity length is long, the first and second oxide constriction layers 106-1 and 106-2 enable current to be efficiently injected into the first active layer 104-1, which is the active layer located near the downstream end of the current path in the cavity (e.g., the active layer farthest from the emission surface ES), and the second oxide constriction layer 106-2 enables current to be efficiently injected into the second active layer 104-2. For example, in the surface-emitting laser 200-2 with a long cavity length, providing an oxide constriction layer near the middle part in the vertical direction (height direction) of the cavity is effective in suppressing current spreading near the middle part. The surface-emitting laser 200-2 is a derivative of the surface-emitting laser 200, and can be manufactured according to the procedure of the flowchart in FIG. 26 (where N=2 and M=1).

[0109] (Variation 3) As shown in FIG. 41, the surface-emitting laser 200-3 of the third modification has a configuration similar to that of the surface-emitting laser 200-1 of the first modification (see FIG. 39), except that a first oxide constriction layer 106-1 is provided between the first active layer 104-1 and the first tunnel junction 108-1, and a second oxide constriction layer 106-2 is provided between the second tunnel junction 108-1 and the third active layer 104-3. In the surface-emitting laser 200-3 of the third modification, even if the active layer has four multi-active layers and the cavity length is long, the first and second oxide constriction layers 106-1 and 106-2 enable current to be efficiently injected into the first active layer 104-1, which is the active layer located near the downstream end of the current path in the cavity (e.g., the active layer farthest from the emission surface ES), and the second oxide constriction layer 106-2 enables current to be efficiently injected into the second active layer 104-2. For example, in the surface-emitting laser 200-3 with a long cavity length, providing an oxide constriction layer near the middle part in the vertical direction (height direction) of the cavity is effective in suppressing current spreading near the middle part. The surface-emitting laser 200-3 requires the second oxide constriction layer 106-2, which increases the number of lamination steps, but can be manufactured by a manufacturing method similar to that for the surface-emitting laser 200-1 of Modification 1 (see FIG. 39).

[0110] (Variation 4) As shown in FIG. 42, the surface-emitting laser 200-4 of the fourth modification has a configuration similar to that of the surface-emitting laser 200 of the second embodiment (see FIG. 23), except that a first oxide constriction layer 106-1 is provided between the first active layer 104-1 and the first tunnel junction 108-1, and a second oxide constriction layer 106-2 is provided between the second tunnel junction 108-1 and the third active layer 104-3. In the surface-emitting laser 200-4 of the fourth variant, even when the active layer has three multi-active layers, the first and second oxide constriction layers 106-1 and 106-2 enable efficient injection of current into the first active layer 104-1, which is the active layer located near the downstream end of the current path in the resonator (e.g., the active layer farthest from the emission surface ES), and the second oxide constriction layer 106-2 enables efficient injection of current into the second active layer 104-2. The surface-emitting laser 200-4 requires the second oxide constriction layer 106-2, which increases the number of lamination steps, but can be manufactured by a manufacturing method similar to that for the surface-emitting laser 200 of the second embodiment.

[0111] 5. Example of a surface-emitting laser configuration to which this technology can be applied Fig. 43 is a plan view showing a surface-emitting laser 2000, which is a structural example of a surface-emitting laser to which the present technology can be applied. Fig. 44A is a cross-sectional view taken along line XX in Fig. 43. Fig. 44B is a cross-sectional view taken along line YY in Fig. 43.

[0112] Each component of the surface-emitting laser 2000 is laminated on a substrate 2001. The substrate 2001 can be configured to include a semiconductor such as GaAs, InGaAs, InP, or InAsP.

[0113] The surface-emitting laser 2000 includes a protection region 2002 (transparent gray region in FIGS. 44A and 44B). As shown in FIG. 43, the protection region 2002 has a circular shape in a plan view, but is not limited to a specific shape and may have another shape such as an ellipse or a polygon. The protection region 2002 includes a material that provides electrical isolation, and is, for example, an ion-implanted region.

[0114] Furthermore, as shown in FIGS. 44A and 44B, the surface-emitting laser 2000 includes a first electrode 2003 and a second electrode 2004. As shown in FIG. 43, the first electrode 2003 has a ring shape having discontinuous portions (intermittent portions) in a plan view, i.e., a split ring shape, but is not limited to a specific shape. As shown in FIG. 44A or 44B, the second electrode 2004 is in contact with the substrate 2001. The first electrode 2003 and the second electrode 2004 are composed of a conductive material such as Ti, Pt, Au, AuGeNi, or PdGeAu. The first electrode 2003 and the second electrode 2004 may have a single-layer structure or a multilayer structure.

[0115] The surface-emitting laser 2000 further includes trenches 2005 provided around the protection region 2002. FIG. 43 shows, as an example, a structure in which six rectangular trenches 2005 are provided in a plan view, but the number and shape of the trenches 2005 are not limited to a specific one. The trenches 2005 are openings for forming an oxidized constriction layer 2006 (including an oxidized region 2006 a and a non-oxidized region 2006 b). During the manufacturing process of the surface-emitting laser 2000, high-temperature water vapor is supplied through the trenches 2005 to form the oxidized region 2006 a of the oxidized constriction layer 2006. For example, the oxidized region 2006 a is Al 2 O 3 formed as a result of oxidation of an AlAs or AlGaAs layer. After the process of forming the oxidized constriction layer 2006, the trenches 2005 may be filled with any dielectric material. Alternatively, the surface may be coated with a dielectric film.

[0116] Furthermore, the surface-emitting laser 2000 includes a dielectric opening 2008 (contact hole) provided in a dielectric layer 2007 on the first electrode 2003. The dielectric layer 2007 may have a multilayer structure as shown in FIGS. 44A and 44B, or may have a single-layer structure. The dielectric layer 2007 includes, for example, silicon oxide or silicon nitride. As shown in FIG. 43, the dielectric opening 2008 is formed in the same shape as the first electrode 2003. However, the shape of the dielectric opening 2008 is not limited to the shape of the first electrode 2003, and the dielectric opening 2008 may be formed partially on the first electrode 2003. The dielectric opening 2008 is filled with a conductive material (not shown), and the conductive material comes into contact with the first electrode 2003.

[0117] 44A and 44B, the surface-emitting laser 2000 includes an optical aperture 2009 inside the first electrode 2003. The surface-emitting laser 2000 emits light through the optical aperture 2009. Furthermore, in the surface-emitting laser 2000, the oxidized region 2006a of the oxidized constriction layer 2006 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.

[0118] 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 called a distributed Bragg reflector.

[0119] The surface-emitting laser 2000 further includes an active layer 2013. The active layer 2013 is disposed between the first multilayer reflector 2011 and the second multilayer reflector 2012, and confines injected carriers to determine the emission wavelength of the surface-emitting laser 2000.

[0120] In this configuration example, the surface-emitting laser 2000 is a surface-emitting surface-emitting laser, but the surface-emitting laser 2000 can also be a bottom-emitting surface-emitting laser.

[0121] As shown in FIGS. 43 and 44A, the substantial diameter of the surface-emitting laser 2000 of this configuration example is the diameter d of an imaginary circle defined by the trench 2005.

[0122] The surface-emitting laser 2000 of this configuration example is manufactured, for example, by the following steps 1 to 8. (Step 1) On the surface of the substrate 2001, the first multilayer reflector 2011, the active layer 2013, a selectively oxidized layer that will become the oxidized constriction layer 2006, and the second multilayer reflector 2012 are epitaxially grown. (Step 2) The first electrode 2003 is formed on the second multilayer reflector 2012 by, for example, lift-off. (Step 3) A trench 2005 is formed by, for example, photolithography. (Step 4) The side surface of the selectively oxidized layer is exposed, and the selectively oxidized layer is selectively oxidized from the side surface to form an oxidized constriction layer 2006 . (Step 5) A protection region 2002 is formed by ion implantation or the like. (Step 6) A dielectric layer 2007 is formed by, for example, vapor deposition or sputtering. (Step 7) A dielectric opening 2008 is formed in the dielectric layer 2007 by, for example, photolithography, to expose the contact point of the first electrode 2003. (Step 8) After the rear surface of the substrate 2001 is polished to make it thinner, a second electrode 2004 is formed on the rear surface of the substrate 2001.

[0123] The number, arrangement, thickness, arrangement order, symmetry, and the like of the layers constituting the surface-emitting laser 2000 described above are merely examples and can be changed as appropriate. That is, 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 43, 44A, and 44B.

[0124] The present technology can be applied to the surface-emitting laser 2000 described above and its modified examples.

[0125] 6. Modifications of this technology The present technology is not limited to the above-described embodiments and modifications, and various modifications are possible.

[0126] For example, the n-type semiconductor layer of the tunnel junction is made of a GaAs-based compound semiconductor, for example, a semiconductor with a high concentration of Si (1x19cm -3 ) may be doped GaAs layer having a thickness of, for example, 20 nm.

[0127] 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 configured.

[0128] In the surface-emitting lasers of the above-described embodiments and modifications, the oxidized constriction layer 113 does not necessarily have to be provided.

[0129] In the surface-emitting lasers of the above-described embodiments and modifications, the contact layer 114 does not necessarily have to be provided.

[0130] In the surface-emitting lasers of the above-described embodiments and modifications, the spacer layers and cladding layers may be omitted as needed.

[0131] In the surface-emitting lasers of the above-described embodiments and modifications, the active layer may have a single-layer structure.

[0132] In the surface-emitting lasers of the above-described embodiments and modifications, the conductivity types (first and second conductivity types) may be interchanged.

[0133] In each of the above-described embodiments and modifications, both the first and second multilayer film reflectors 102 and 112 are semiconductor multilayer film reflectors, but the present invention is not limited to this. For example, the first multilayer reflector 102 may be a semiconductor multilayer reflector, and the second multilayer reflector 112 may be a dielectric multilayer reflector. A dielectric multilayer reflector is also a type of distributed Bragg reflector. For example, the first multilayer reflector 102 may be a dielectric multilayer reflector, and the second multilayer reflector 112 may be a semiconductor multilayer reflector. For example, both the first and second multilayer film reflectors 102 and 112 may be dielectric multilayer film reflectors. The semiconductor multilayer reflector has low light absorption and is electrically conductive, making it suitable for the second multilayer reflector 112 located on the emission side (front surface) and on the current path from the anode electrode 116 to each active layer. On the other hand, a dielectric multilayer reflector has extremely low light absorption, and from this point of view, a dielectric multilayer reflector is suitable for the second multilayer reflector 112 on the emission side (front surface side).

[0134] In the above-described embodiments and modified examples, a surface-emitting surface-emitting laser that emits laser light from the top of the mesa has been used as an example. However, the present technology can also be applied to a back-emitting surface-emitting laser that emits laser light from the back surface of the substrate (using the back surface of the substrate as the emission surface). 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 to serve as an emission port.

[0135] In the above-described embodiments and modifications, the surface-emitting laser 10 using an AlGaAs-based compound semiconductor has been described as an example, but the present technology can also be applied to a surface-emitting laser using, for example, a GaN-based compound semiconductor. Specifically, at least one of the first and second multilayer reflectors 102, 112 may be a GaN-based semiconductor multilayer reflector, or at least one of the first and second multilayer reflectors 102, 112 may be a GaN-based dielectric multilayer reflector. The GaN-based compound semiconductor used for at least one of the first and second multilayer reflectors 102 and 112 may be, for example, GaN / AlGaN.

[0136] Parts of the configurations of the surface-emitting lasers of the above-described embodiments and modifications may be combined within a range that does not contradict each other.

[0137] 7. Application examples to electronic devices The technology according to the present disclosure (the present technology) can be applied to various products (electronic devices). For example, the technology according to the present disclosure may be realized as a device mounted on any type of moving body, such as an automobile, an electric vehicle, a hybrid electric vehicle, a motorcycle, a bicycle, personal mobility, an airplane, a drone, a ship, or a robot.

[0138] The surface-emitting laser according to the present technology can also be used as a light source for devices that form or display images using laser light (for example, laser printers, laser copiers, projectors, head-mounted displays, head-up displays, etc.).

[0139] 8.<Example of applying a surface-emitting laser to a distance measurement device> Hereinafter, application examples of the surface-emitting lasers according to the above-described embodiments and modifications will be described.

[0140] 45 illustrates an example of a schematic configuration of a distance measurement device 1000 including a surface-emitting laser 100, as an example of an electronic device according to the present technology. The distance measurement device 1000 measures the distance to a subject S by a TOF (Time Of Flight) method. The distance measurement device 1000 includes the surface-emitting laser 100 as a light source. The distance measurement device 1000 includes, for example, the 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.

[0141] The light receiving device 120 detects the light reflected by the subject S. The lens 119 is a collimating lens that collimates the light emitted from the surface-emitting laser 100. The lens 130 is a condensing lens that collects the light reflected by the subject S and guides it to the light receiving device 120.

[0142] 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 may be a signal input from the control unit 150, or may be an 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 the 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.

[0143] In this application example, instead of the surface-emitting laser 100, any of the surface-emitting lasers 100-1 to 100-6, 200, and 200-1 to 200-4 can be applied to the distance measurement device 1000. 9.<Example of distance measurement device mounted on a moving object>

[0144] FIG. 46 is a block diagram showing a schematic configuration example of a vehicle control system, which is an example of a mobile object control system to which the technology according to the present disclosure can be applied.

[0145] The vehicle control system 12000 includes a plurality of electronic control units connected via a communication network 12001. In the example shown in Fig. 46, the vehicle control system 12000 includes a drive system control unit 12010, a body system control unit 12020, an outside-of-vehicle information detection unit 12030, an inside-vehicle information detection unit 12040, and an integrated control unit 12050. Also shown as functional components of the integrated control unit 12050 are a microcomputer 12051, an audio / video output unit 12052, and an in-vehicle network I / F (interface) 12053.

[0146] The drivetrain control unit 12010 controls the operation of devices related to the drivetrain of the vehicle in accordance with various programs. For example, the drivetrain control unit 12010 functions as a control device for a drive force generating device for generating a drive force of the vehicle, such as an internal combustion engine or a drive motor, a drive force transmission mechanism for transmitting the drive force to the wheels, a steering mechanism for adjusting the steering angle of the vehicle, a braking device for generating a braking force of the vehicle, etc.

[0147] The body system control unit 12020 controls the operation of various devices equipped in 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 device, or various lamps such as headlamps, backup lamps, brake lamps, turn signals, and fog lamps. In this case, radio waves transmitted from a portable device that serves as a key or signals from various switches may be input to the body system control unit 12020. The body system control unit 12020 receives these radio waves or signals and controls the vehicle's door lock device, power window device, lamps, etc.

[0148] The outside-vehicle information detection unit 12030 detects information outside the vehicle equipped with the vehicle control system 12000. For example, a distance measurement device 12031 is connected to the outside-vehicle information detection unit 12030. The distance measurement device 12031 includes the above-described distance measurement device 1000. The outside-vehicle information detection unit 12030 causes the distance measurement device 12031 to measure the distance to an object outside the vehicle (subject S), and acquires the distance data obtained thereby. The outside-vehicle information detection unit 12030 may perform object detection processing for people, cars, obstacles, signs, etc. based on the acquired distance data.

[0149] The in-vehicle information detection unit 12040 detects information inside the vehicle. For example, a driver state detection unit 12041 that detects the state of the driver is connected to the in-vehicle information detection unit 12040. The driver state detection unit 12041 includes, for example, a camera that captures an image of the driver, and the in-vehicle information detection unit 12040 may calculate the degree of fatigue or concentration of the driver based on the detection information input from the driver state detection unit 12041, or may determine whether the driver is dozing off.

[0150] The microcomputer 12051 can calculate control target values for the driving force generating device, steering mechanism, or braking device based on the information inside and outside the vehicle acquired by the outside-vehicle information detection unit 12030 or the inside-vehicle information detection unit 12040, and output control commands to the drivetrain control unit 12010. For example, the microcomputer 12051 can perform cooperative control aimed at realizing the functions of an ADAS (Advanced Driver Assistance System), including avoiding or mitigating collisions between vehicles, following based on the distance between vehicles, maintaining vehicle speed, warning of vehicle collisions, or warning of vehicle lane departure.

[0151] In addition, the microcomputer 12051 can perform cooperative control for the purpose of autonomous driving, which allows the vehicle to travel autonomously without relying on driver operation, by controlling the driving force generating device, steering mechanism, braking device, etc. based on information about the surroundings of the vehicle obtained by the outside vehicle information detection unit 12030 or the inside vehicle information detection unit 12040.

[0152] Furthermore, the microcomputer 12051 can output a control command to the body system control unit 12020 based on the information about the outside of the vehicle acquired by the outside information detection unit 12030. For example, the microcomputer 12051 can control the headlamps according to the position of a preceding vehicle or an oncoming vehicle detected by the outside information detection unit 12030, and perform cooperative control for the purpose of preventing glare, such as switching from high beams to low beams.

[0153] The audio / video output unit 12052 transmits at least one of audio and video output signals to an output device capable of visually or audibly notifying information to passengers in the vehicle or to the outside of the vehicle. In the example of Fig. 46, an audio speaker 12061, a display unit 12062, and an instrument panel 12063 are exemplified as output devices. The display unit 12062 may include, for example, at least one of an on-board display and a head-up display.

[0154] FIG. 47 is a diagram showing an example of the installation position of the distance measurement device 12031.

[0155] In FIG. 47, a vehicle 12100 has distance measurement devices 12101, 12102, 12103, 12104, and 12105 as a distance measurement device 12031.

[0156] Distance measuring devices 12101, 12102, 12103, 12104, and 12105 are provided, for example, at positions such as the front nose, side mirrors, rear bumper, back door, and the top of the windshield inside the vehicle cabin of vehicle 12100. Distance measuring device 12101 provided at the front nose and distance measuring device 12105 provided at the top of the windshield inside the vehicle cabin mainly acquire data ahead of vehicle 12100. Distance measuring devices 12102 and 12103 provided at the side mirrors mainly acquire data on the sides of vehicle 12100. Distance measuring device 12104 provided at the rear bumper or back door mainly acquires data behind vehicle 12100. The forward data acquired by distance measuring devices 12101 and 12105 is mainly used to detect preceding vehicles, pedestrians, obstacles, traffic lights, traffic signs, etc.

[0157] 47 shows an example of the detection ranges of the distance measurement devices 12101 to 12104. Detection range 12111 indicates the detection range of the distance measurement device 12101 provided on the front nose, detection ranges 12112 and 12113 indicate the detection ranges of the distance measurement devices 12102 and 12103 provided on the side mirrors, respectively, and detection range 12114 indicates the detection range of the distance measurement device 12104 provided on the rear bumper or back door.

[0158] For example, the microcomputer 12051 can extract, as a preceding vehicle, the three-dimensional object that is the closest three-dimensional object on the path of the vehicle 12100 and traveling in approximately the same direction as the vehicle 12100 at a predetermined speed (for example, 0 km / h or higher) by calculating the distance to each three-dimensional object within the detection ranges 12111 to 12114 and the change in this distance over time (relative speed with respect to the vehicle 12100) based on the distance data obtained from the distance measuring devices 12101 to 12104. Furthermore, the microcomputer 12051 can set a vehicle-to-vehicle distance to be maintained in advance in front of the preceding vehicle, and perform automatic braking control (including follow-up stop control), automatic acceleration control (including follow-up start control), etc. In this way, cooperative control can be performed for the purpose of automatic driving, which travels autonomously without relying on driver operation.

[0159] For example, the microcomputer 12051 classifies and extracts three-dimensional object data regarding three-dimensional objects into two-wheeled vehicles, ordinary vehicles, large vehicles, pedestrians, utility poles, and other three-dimensional objects based on distance data obtained from the distance measuring devices 12101 to 12104, and can use the data for automatic obstacle avoidance. For example, the microcomputer 12051 distinguishes obstacles around the vehicle 12100 into obstacles that are visible to the driver of the vehicle 12100 and obstacles that are difficult to see. The microcomputer 12051 then determines the collision risk, which indicates the degree of risk of collision with each obstacle, and when the collision risk is equal to or greater than a set value and a collision is possible, the microcomputer 12051 can provide driving assistance for collision avoidance by outputting an alarm to the driver via the audio speaker 12061 or the display unit 12062, or by performing forced deceleration or avoidance steering via the drivetrain control unit 12010.

[0160] An example of a mobile object control system to which the technology according to the present disclosure can be applied has been described above. The technology according to the present disclosure can be applied to the distance measurement device 12031 in the above-described configuration.

[0161] The specific numerical values, shapes, materials (including compositions) and the like described in this specification are merely examples and are not intended to limit the invention.

[0162] The present technology can also be configured as follows. (1) first and second multilayer reflectors; a plurality of active layers stacked one on top of the other between the first and second multilayer film reflectors; a tunnel junction disposed between two active layers adjacent to each other in a stacking direction among the plurality of active layers; an oxide constriction layer disposed between one of the two adjacent active layers and the tunnel junction; A surface-emitting laser comprising: (2) The surface-emitting laser according to (1), wherein the one active layer is disposed at a position farther from the emission surface of the surface-emitting laser than the other active layer of the two adjacent active layers. (3) A surface-emitting laser according to (1) or (2), wherein the one active layer is positioned closer to one of the first and second multilayer film reflectors that is farther from the emission surface of the surface-emitting laser than the other of the first and second multilayer film reflectors that is closer to the emission surface of the surface-emitting laser. (4) A surface-emitting laser according to (1) or (2), wherein the one active layer is positioned closer to the other of the first and second multilayer film reflectors that is closer to the emission surface of the surface-emitting laser than one of the first and second multilayer film reflectors that is farther from the emission surface of the surface-emitting laser. (5) The surface-emitting laser according to (1), wherein the one active layer is disposed closer to the emission surface of the surface-emitting laser than the other active layer of the two adjacent active layers. (6) A surface-emitting laser according to (1) or (5), wherein the one active layer is positioned closer to one of the first and second multilayer film reflectors that is farther from the emission surface of the surface-emitting laser than the other of the first and second multilayer film reflectors that is closer to the emission surface of the surface-emitting laser. (7) A surface-emitting laser according to (1) or (5), wherein the one active layer is positioned closer to the other of the first and second multilayer film reflectors that is closer to the emission surface than the other of the first and second multilayer film reflectors that is farther from the emission surface. (8) the plurality of active layers is at least three active layers; the tunnel junction is disposed between two adjacent active layers of each set of at least two sets of two adjacent active layers among the plurality of active layers; The surface-emitting laser according to any one of (1) to (7), wherein the oxide constriction layer is disposed between one active layer of at least one pair of adjacent active layers among the at least two pairs of adjacent active layers and the tunnel junction disposed between the two adjacent active layers. (9) The surface-emitting laser according to (8), wherein the at least three active layers include first, second, and third active layers, the first, second, and third active layers being stacked in this order, a first tunnel junction being the tunnel junction being disposed between the first and second active layers, a second tunnel junction being the tunnel junction being disposed between the second and third active layers, and the oxide constriction layer being disposed between the first active layer and the first tunnel junction and / or between the second active layer and the second tunnel junction. (10) The surface-emitting laser according to (9), wherein the first active layer is the active layer disposed at a position farthest from the emission surface of the surface-emitting laser among the plurality of active layers. (11) The surface-emitting laser according to (9) or (10), wherein a first oxide constriction layer, which is the oxide constriction layer, is disposed between the first active layer and the first tunnel junction. (12) The surface-emitting laser according to any one of (9) to (11), wherein a second oxide constriction layer, which is the oxide constriction layer, is disposed between the second active layer and the second tunnel junction. (13) The surface-emitting laser according to any one of (9) to (11), wherein the oxide constriction layer is not disposed between the second active layer and the second tunnel junction. (14) A surface-emitting laser according to any one of (1) to (13), wherein another oxide constriction layer is disposed inside one of the first and second multilayer film reflectors that is closer to the emission surface of the surface-emitting laser. (15) The surface-emitting laser according to (14), wherein the oxidized constriction layer and the additional oxidized constriction layer are both formed by selectively oxidizing a layer made of an AlGaAs-based compound semiconductor. (16) The surface-emitting laser according to (14) or (15), wherein the oxidized constriction layer and the another oxidized constriction layer are different from each other in Al composition and / or optical thickness. (17) The surface-emitting laser according to any one of (1) to (16), wherein the tunnel junction has a layer structure in which a p-type semiconductor layer and an n-type semiconductor layer are stacked on top of each other, and the oxide constriction layer is disposed on the p-type semiconductor layer side. (18) A surface-emitting laser according to any one of (1) to (17), wherein the one active layer, the tunnel junction, and the oxide constriction layer are arranged within an optical thickness of 3λ / 4, where λ is the oscillation wavelength of the surface-emitting laser. (19) An electronic device comprising the surface-emitting laser according to any one of (1) to (18). (20) forming a laminate by stacking a structure including a stacked structure in which a first active layer, a selectively oxidized layer, a tunnel junction, and a second active layer are stacked in this order on a first multilayer reflector, and stacking a second multilayer reflector on the structure; forming a mesa by etching the stacked body until at least the side surface of the selectively oxidized layer is exposed; a step of selectively oxidizing the selectively oxidized layer from a side surface thereof to form an oxidized constriction layer; A method for manufacturing a surface-emitting laser, comprising: (21) A surface-emitting laser array including a plurality of surface-emitting lasers according to any one of (1) to (20). (22) An electronic device comprising the surface-emitting laser according to any one of (1) to (20). (23) An electronic device comprising the surface-emitting laser array according to (21). [Explanation of symbols]

[0163] 100, 100-1 to 100-6, 200, 200-1 to 200-4: surface-emitting laser, 101: substrate, 102: first multilayer reflector, 104-1: first active layer, 104-2: second active layer, 104-3: third active layer, 106: oxide constriction layer, 106-1: first oxide constriction layer, 106-2: second oxide constriction layer, 108: tunnel junction, 108-1: first tunnel junction, 108-2: second tunnel junction, 108a: p-type semiconductor layer, 108b: n-type semiconductor layer, 112: second multilayer reflector, 113: oxide constriction layer (another oxide constriction layer).

Claims

1. a first multilayer reflector, a first active layer, a first oxide constriction layer, a first tunnel junction layer, a second active layer, a second oxide constriction layer, and at least a part of a second multilayer reflector are stacked in this order; the second oxide constriction layer is disposed inside the second multilayer film reflector, the first oxide constriction layer is not provided in the multilayer reflector; The first oxide constriction layer and the second oxide constriction layer have different optical thicknesses.

2. 2. The surface-emitting laser according to claim 1, wherein the first oxidized constriction layer and the second oxidized constriction layer have different Al compositions.

3. 2. The surface-emitting laser according to claim 1, wherein no active layer is provided on the second oxide constriction layer on the side of the emission surface of the surface-emitting laser.

4. 2. The surface-emitting laser according to claim 1, further comprising a spacer layer provided between said first oxide constriction layer and said first tunnel junction layer.

5. 5. The surface-emitting laser according to claim 1, wherein each of the first multilayer reflector and the second multilayer reflector has a structure in which a plurality of types of semiconductor layers having different refractive indices are alternately stacked with an optical thickness of ¼ wavelength of the oscillation wavelength.

6. 5. The surface-emitting laser according to claim 1, wherein each of the first active layer and the second active layer has a structure in which an active region and a guide barrier region are alternately stacked.

7. 5. The surface-emitting laser according to claim 1, wherein each of the first oxidized constriction layer and the second oxidized constriction layer has a non-oxidized region and an oxidized region surrounding the non-oxidized region.

8. 5. The surface-emitting laser according to claim 1, wherein the first tunnel junction layer has a structure in which a p-type semiconductor layer and an n-type semiconductor layer are stacked.

9. 5. The surface-emitting laser according to claim 1, wherein the first oxidized constriction layer and the second oxidized constriction layer have different oxidized constriction diameters.

10. 5. The surface-emitting laser according to claim 1, wherein a third oxide constriction layer, a second tunnel junction layer, and a third active layer are further stacked in this order between the second active layer and the second multilayer film reflector.

11. a first multilayer reflector, a first active layer, a first oxide constriction layer, a first tunnel junction layer, a second active layer, a second oxide constriction layer, and at least a part of a second multilayer reflector are stacked in this order; the second oxide constriction layer is disposed inside the second multilayer film reflector, the first oxide constriction layer is not provided in the multilayer reflector; A distance measuring device comprising a surface-emitting laser, wherein the first oxide constriction layer and the second oxide constriction layer have different optical thicknesses.

12. The distance measuring device according to claim 11 , wherein the first oxidized constriction layer and the second oxidized constriction layer have different Al compositions.

13. 12. The distance measuring device according to claim 11, wherein no active layer is provided on the second oxide constriction layer on the side of the emission surface of the surface-emitting laser.

14. The distance measuring device according to claim 11 , further comprising a spacer layer provided between the first oxide constriction layer and the first tunnel junction layer.

15. A distance measuring device according to any one of claims 11 to 14, wherein each of the first multilayer reflector and the second multilayer reflector has a structure in which multiple types of semiconductor layers having different refractive indices are alternately stacked with an optical thickness of 1 / 4 wavelength of the oscillation wavelength.

16. 15. The distance measuring device according to claim 11, wherein each of the first active layer and the second active layer has a structure in which active regions and guide barrier regions are alternately stacked.

17. 15. The distance measuring device according to claim 11, wherein each of the first oxidized constriction layer and the second oxidized constriction layer has a non-oxidized region and an oxidized region surrounding the non-oxidized region.

18. 15. The distance measuring device according to claim 11, wherein the first tunnel junction layer has a structure in which a p-type semiconductor layer and an n-type semiconductor layer are stacked.

19. 15. The distance measuring device according to claim 11, wherein an oxidation constriction diameter of the first oxidation constriction layer and an oxidation constriction diameter of the second oxidation constriction layer are different from each other.

20. 15. The distance measuring device according to claim 11, wherein a third oxide constriction layer, a second tunnel junction layer, and a third active layer are further stacked in this order between the second active layer and the second multilayer reflector.

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