Light emitting element and distance measuring system

Abstract

[Problem] To simplify an element structure and improve power efficiency and light output characteristics. [Solution] This light emitting element includes: a laminated semiconductor layer which has an active layer for performing surface emission; and a first reflection layer which reflects light emitted at the active layer and propagating in a light emission direction of the laminated semiconductor layer. The laminated semiconductor layer includes: a second reflection layer that reflects light emitted at the active layer and propagating in a direction opposite to the light emission direction of the laminated semiconductor layer, and resonates, between the first reflection layer and the second reflection layer, the light emitted at the active layer; a first cladding layer disposed between the active layer and the first reflection layer; a contact layer which is disposed inside the first cladding layer and allows a current to flow to the active layer; and a second cladding layer disposed between the active layer and the second reflection layer.

Description

Light emitting element and distance measuring system

[0001] The present disclosure relates to a light emitting device and a ranging system.

[0002] A surface-emitting semiconductor laser having a current confinement structure fabricated by partially increasing the resistance through ion implantation has been disclosed (see Patent Document 1). In Patent Document 1, the location of the contact layer is optimized to suppress light absorption in the contact layer, while achieving high optical output with a low threshold current.

[0003] Japanese Patent Application Laid-Open No. 2003-347671

[0004] In Patent Document 1, the contact layer is positioned so as to be offset from the antinode of the standing wave of light inside the surface-emitting semiconductor laser element. However, since the contact layer in Patent Document 1 is provided inside a semiconductor DBR (Distributed Bragg Reflector), the current from the contact layer must pass through the band discontinuity structure of the semiconductor DBR, resulting in large power loss due to resistance in the semiconductor DBR layer. Furthermore, since the semiconductor DBR between the contact layer and the active layer is a current path, impurities must be implanted, which causes light absorption in the semiconductor DBR.

[0005] Therefore, the present disclosure provides a light emitting element and a distance measuring system that have a simple element structure and excellent power efficiency and optical output characteristics.

[0006] In order to solve the above problems, the present disclosure provides a light-emitting element comprising: a laminated semiconductor layer having an active layer that performs surface emission; and a first reflective layer that reflects light emitted in the active layer and propagating in the light emission direction of the laminated semiconductor layer, wherein the laminated semiconductor layer has: a second reflective layer that reflects light emitted in the active layer and propagating in the opposite direction to the light emission direction of the laminated semiconductor layer, and causes the light emitted in the active layer to resonate between the first reflective layer and the laminated semiconductor layer; a first cladding layer disposed between the active layer and the first reflective layer; a contact layer disposed inside the first cladding layer and that passes a current to the active layer; and a second cladding layer disposed between the active layer and the second reflective layer.

[0007] The first cladding layer may include a third cladding layer disposed closer to the first reflecting layer than the contact layer, and a fourth cladding layer disposed closer to the active layer than the contact layer.

[0008] The first reflective layer and the second reflective layer may constitute at least a part of a resonator that resonates light generated in the active layer, and the contact layer may be disposed at a node of a standing wave of light resonated in the resonator.

[0009] The resonator may resonate light of a predetermined wavelength λ and generate a node of the standing wave at a position xλ / 2+λ / 4 (x is an integer greater than or equal to 0) from the first reflective layer, and the contact layer may be positioned at the position of at least one of the multiple nodes of the standing wave.

[0010] The contact layer may have a higher impurity concentration than the first cladding layer.

[0011] The contact layer may include a material having a smaller bandgap than the first cladding layer.

[0012] The first cladding layer may include InP, and the contact layer may include at least one of InGaAs, InGaAsP, and AlGaInAs.

[0013] The contact layer and the first cladding layer may include InP.

[0014] The active layer, the first cladding layer, and the contact layer may have a current confinement structure formed by ion implantation, and the contact layer may be made of a compound semiconductor material that does not cause high resistance due to ion implantation.

[0015] The third cladding layer may be an undoped layer.

[0016] A light control member for controlling light generated in the active layer may be provided at the interface between the first cladding layer and the first reflecting layer.

[0017] The light control member may include at least one of a diffraction grating, a diffractive lens, a sub-wavelength grating, an equivalent lens, a metasurface, or a trench.

[0018] The laminated semiconductor layer may include a plurality of the active layers, and a plurality of tunnel junction layers that inject current into the plurality of active layers.

[0019] The second reflective layer may include InP and AlGaInAs.

[0020] The second reflective layer may include GaAs and AlGaAs.

[0021] The active layer may have a quantum well structure or a quantum dot structure.

[0022] The semiconductor device may further include an electrode for passing a current through the active layer, the electrode including AuGe, and the first cladding layer and the contact layer including a diffusion region of the AuGe.

[0023] The laminated semiconductor layer may have a plurality of light-emitting regions each arranged along the light emission surface and each having the active layer, the first reflective layer, the second reflective layer, the first cladding layer, the contact layer, and the second cladding layer.

[0024] The present disclosure also provides a ranging system comprising: a light-emitting element; and a ranging unit that measures a distance to an object to be measured based on light emitted from the light-emitting element and light reflected from the object to be measured, wherein the light-emitting element comprises: a laminated semiconductor layer having an active layer that performs surface emission; and a first reflective layer that reflects light emitted in the active layer and propagating in the light emission direction of the laminated semiconductor layer, and the laminated semiconductor layer comprises: a second reflective layer that reflects light emitted in the active layer and propagating in the opposite direction to the light emission direction of the laminated semiconductor layer, and resonates the light emitted in the active layer between the first reflective layer and the laminated semiconductor layer, a first cladding layer arranged between the active layer and the first reflective layer, a contact layer arranged inside the first cladding layer and that passes a current through the active layer, and a second cladding layer arranged between the active layer and the second reflective layer.

[0025] The light emitting element may include a light receiving element that receives the reflected light, and a support substrate that supports the light emitting element and the light receiving element.

[0026] FIG. 1 is a cross-sectional view showing a first configuration example of the light-emitting element according to the first embodiment of the present disclosure. FIG. 2 is a cross-sectional view showing a second configuration example of the light-emitting element according to the first embodiment of the present disclosure. FIG. 3 is a plan view of the light-emitting element according to the first embodiment of the present disclosure. FIG. 4 is a view showing a stacking and epitaxial growth process of the light-emitting element according to the first embodiment of the present disclosure. FIG. 5 is a view showing a process of forming a resist mask for ion implantation of the light-emitting element according to the first embodiment of the present disclosure. FIG. 6 is a view showing an ion implantation process of the light-emitting element according to the first embodiment of the present disclosure. FIG. 7 is a view showing a process of removing the resist mask for ion implantation of the light-emitting element according to the first embodiment of the present disclosure. FIG. 8 is a view showing a process of forming a hard mask for dry etching of the epitaxial growth layer of the light-emitting element according to the first embodiment of the present disclosure. FIG. 9 is a view showing a process of etching the hard mask of the light-emitting element according to the first embodiment of the present disclosure. FIG. 10 is a view showing a process of removing the resist mask for etching the hard mask of the light-emitting element according to the first embodiment of the present disclosure. FIG. 11 is a view showing a process of dry etching the epitaxial growth layer of the light-emitting element according to the first embodiment of the present disclosure. FIG. 1 is a diagram illustrating a wet etching process for a cladding layer of a light-emitting element according to a first embodiment of the present disclosure; FIG. 2 is a diagram illustrating a process for removing a resist mask for an upper contact of a light-emitting element according to a first embodiment of the present disclosure; FIG. 3 is a diagram illustrating a process for forming a protective film of a light-emitting element according to a first embodiment of the present disclosure; FIG. 4 is a diagram illustrating a process for forming a resist mask for dry etching of a protective film of a light-emitting element according to a first embodiment of the present disclosure; FIG. 5 is a diagram illustrating a process for dry etching of a protective film of a light-emitting element according to a first embodiment of the present disclosure; FIG. 6 is a diagram illustrating a process for removing a resist mask for dry etching of a protective film of a light-emitting element according to a first embodiment of the present disclosure; FIG. 7 is a diagram illustrating a process for forming a resist mask for electrode vapor deposition of a light-emitting element according to a first embodiment of the present disclosure; FIG. 8 is a diagram illustrating an electrode vapor deposition process of a light-emitting element according to a first embodiment of the present disclosure; FIG. 9 is a diagram illustrating a lift-off process of a light-emitting element according to a first embodiment of the present disclosure.FIG. 1 is a diagram illustrating a step of forming an upper reflective layer of a light-emitting element according to a first embodiment of the present disclosure. FIG. 2 is a cross-sectional view illustrating a light-emitting element according to a first comparative example. FIG. 3 is a cross-sectional view illustrating a light-emitting element according to a second comparative example. FIG. 4 is a cross-sectional view illustrating a light-emitting element according to a third comparative example. FIG. 5 is a cross-sectional view illustrating a light-emitting element according to a fourth comparative example. FIG. 6 is a cross-sectional view illustrating a light-emitting element according to a second embodiment of the present disclosure. FIG. 7 is a cross-sectional view illustrating a light-emitting element according to a fourth embodiment of the present disclosure. FIG. 8 is a side view illustrating a first configuration example of a light control member. FIG. 9 is a top view illustrating a second configuration example of a light control member. FIG. 10 is a top view illustrating a second configuration example of a light control member. FIG. 11 is a cross-sectional view illustrating a light-emitting element according to a fifth embodiment of the present disclosure. FIG. 12 is a cross-sectional view illustrating a light-emitting element according to a sixth embodiment of the present disclosure. FIG. 13 is a cross-sectional view illustrating a light-emitting element according to a seventh embodiment of the present disclosure. FIG. 14 is a cross-sectional view illustrating a light-emitting element according to an eighth embodiment of the present disclosure. FIG. 15 is a plan view illustrating a light-emitting element according to a ninth embodiment of the present disclosure. FIG. 16 is a cross-sectional view illustrating a light-emitting element according to the ninth embodiment of the present disclosure. FIG. 2 is an explanatory diagram showing an example of the installation positions of an outside-vehicle information detection unit and an imaging unit.

[0027] Hereinafter, embodiments of a light-emitting element and a distance measurement system will be described with reference to the drawings. The following description will focus on the main components of the light-emitting element and distance measurement system, but the light-emitting element and distance measurement system may include components and functions that are not shown or described. The following description does not exclude components and functions that are not shown or described.

[0028] 1A is a cross-sectional view showing a first configuration example of a light-emitting element according to a first embodiment of the present disclosure. The light-emitting element 1 of Fig. 1A is used, for example, as a light source for a distance measurement system. Fig. 1A shows an example in which the light-emitting element 1 is a VCSEL (Vertical Cavity Surface Emitting Laser).

[0029] The light-emitting element 1 has a substrate 2, a protective film 3, an electrode (lower electrode) 4, an electrode (upper electrode) 5, a laminated semiconductor layer 10, and a reflective layer (first reflective layer) 17. The laminated semiconductor layer 10 is disposed on the substrate 2 and processed into a mesa shape. The reflective layer 17 is laminated on the laminated semiconductor layer 10. The laminated semiconductor layer 10 is formed by laminating, in this order from the substrate 2 side, a reflective layer (second reflective layer) 11, a cladding layer (fifth cladding layer) 12, an active layer 13, a cladding layer (second cladding layer) 14, a tunnel junction layer 15, and a cladding layer (first cladding layer) 16. The light-emitting element 1 emits laser light from an end face (light-emitting surface A1) of the reflective layer 17 opposite the substrate 2.

[0030] The substrate 2 is, for example, an InP substrate, and has a thickness sufficient to maintain mechanical strength when the light emitting element 1 is bonded to other members.

[0031] The reflective layer 11 is used as a DBR that reflects light of wavelength λ that propagates in the opposite direction to the emission direction of the laser light, out of the light generated in the active layer 13. The reflective layer 11 is made of InP / AlGaInAs or the like.

[0032] The reflective layer 11 and the reflective layer 17 constitute a resonator 6 that resonates the light emitted by the active layer 13 .

[0033] The cladding layer 12 is used to confine charges in the active layer 13. The cladding layer 12 is, for example, an n-type cladding layer, and is made of n-InP or the like.

[0034] The active layer 13 emits and amplifies spontaneously emitted light. The active layer 13 has a quantum well (QW) structure in which quantum well layers with small bandgaps and barrier layers with large bandgaps are alternately stacked. The structure of the active layer 13 is not limited to the quantum well structure, and may have a quantum dot (QDs) structure or the like. The active layer 13 is made of, for example, AlGaInAs or the like.

[0035] The cladding layer 14 is used to confine charges in the active layer 13. The cladding layer 14 is, for example, a p-type cladding layer, and is made of p-InP or the like.

[0036] The tunnel junction layer 15 has a current confinement structure due to a tunnel junction. The tunnel junction layer 15 is made of, for example, a p-type semiconductor material with a high impurity concentration and an n-type semiconductor material with a high impurity concentration (specifically, n ＋ -InP / p ＋ The tunnel junction layer 15 uniformly injects charges into the entire active layer 13 through the tunnel junction.

[0037] The cladding layer 16 is used to confine charges in the active layer 13 and the tunnel junction layer 15. The cladding layer 16 according to the present disclosure also includes a contact layer. More specifically, the cladding layer 16 is configured by stacking a cladding layer (third cladding) 21, a contact layer 22, and a cladding layer (fourth cladding layer) 23 in this order from the substrate 2 side.

[0038] The cladding layer 21 is disposed between the active layer 13 and the contact layer 22. The cladding layer 23 is disposed between the reflective layer 17 and the contact layer 22. The cladding layers 21 and 23 are made of, for example, n-InP.

[0039] The cladding layers 21 and 23 are used to adjust the optical distance between the reflective layer 17 and the contact layer 22. The cladding layers 21 and 23 position the contact layer 22 at the position of a node of the standing wave of light resonated in the resonator 6. In this specification, the space in which the standing wave of light resonated in the resonator 6 exists is also referred to as the optical field, the position of the node of the standing wave is also referred to as the minimum region of the optical field, and the position of the antinode of the standing wave is also referred to as the maximum region of the optical field.

[0040] The contact layer 22 is a layer formed by implanting impurities at a higher concentration than the cladding layers 21 and 23, and has a lower electrical resistance than the cladding layers 21 and 23. The contact layer 22 is made of a material with a lower bandgap than the cladding layers 21 and 23, for example, n ＋ The contact layer 22 is made of InGaAs, etc. The contact layer 22 is connected to the electrode 5 and forms a current path 7 for supplying a current from the electrode 5 to the active layer 13 .

[0041] Similar to the reflective layer 11, the reflective layer 17 is used as a DBR that reflects light of wavelength λ. The reflective layer 17 reflects light emitted from the active layer 13 that propagates in the emission direction of the laser light and passes through the tunnel junction layer 15. The reflective layer 17 is, for example, a dielectric DBR, and is made of TiO / SiO or the like.

[0042] The protective film 3 covers the laminated semiconductor layer 10 and insulates and protects the laminated semiconductor layer 10. The protective film 3 is made of, for example, SiN.

[0043] The electrode 4 is also called a cathode electrode, and the electrode 5 is also called an anode electrode. The electrodes 4 and 5 are made of a metal (for example, Au, Pt, or Ti).

[0044] When a voltage is applied between the electrodes 4 and 5, a current flows between the electrodes 4 and 5. As a result, the tunnel junction layer 15 injects charges into the active layer 13. As a result, spontaneous emission of light occurs from the active layer 13.

[0045] Spontaneous emission light generated in the active layer 13 travels in the stacking direction of the light-emitting element 1 and is reflected by the reflective layers 11 and 17. Because the reflective layers 11 and 17 are configured to reflect light having an oscillation wavelength λ, the component of the spontaneous emission light having the oscillation wavelength λ generates a standing wave (also called resonance) in the resonator 6 and is amplified by the active layer 13. When the charge injected into the active layer 13 exceeds a predetermined threshold, the light forming the standing wave undergoes laser oscillation and passes through the reflective layer 17, and laser light is emitted from the light-emitting surface A1.

[0046] 1A has a current path 7 that supplies current from the electrode 5 to the active layer 13. The current path 7 is made of a contact layer 22 with low electrical resistance, and therefore the electrical characteristics of the light-emitting element 1 can be improved.

[0047] Fig. 2 is a plan view of the light-emitting device according to the first embodiment of the present disclosure. Fig. 1A is a cross-sectional view taken along line AA' in Fig. 2. Fig. 2 illustrates a substrate 2, a protective film 3, an electrode (BMT: Bottom Metal) 4, an electrode (TMT: Top Metal) 5, and a reflective layer (DBR) 17. As shown in Fig. 2, the electrode 5 is arranged in an annular shape so as to surround the reflective layer 17.

[0048] 1B is a cross-sectional view showing a second configuration example of the light-emitting element according to the first embodiment of the present disclosure. The light-emitting element 1a shown in FIG. 1B differs from the light-emitting element 1 of FIG. 1A in that it has a current confinement structure formed by ion implantation. Specifically, after a mask is applied to the laminated semiconductor layer 10 in the light-emitting element 1a, predetermined impurity ions (e.g., He) are implanted from the top surface to form an ion-implanted region (first region) 31. The predetermined ions may be composed of at least one of H, B, and O.

[0049] Ions are not implanted into the masked region of the laminated semiconductor layer 10. This region is used to emit laser light, and is therefore referred to as a light emitting region (second region) 32 in this specification.

[0050] The ion implantation region 31 has a higher resistance than the light emitting region 32. Furthermore, the tunnel junction layer 15 in the ion implantation region 31 loses the tunnel effect. As a result, current confinement can be achieved, confining the current supplied to the electrodes 4 and 5 to the light emitting region 32.

[0051] In current confinement by ion implantation, the resistance of the side surface of the light-emitting element increases, which in turn increases the resistance of the region that serves as the current path from the upper electrode. This increases the voltage required to inject charges into the active layer, which leads to a deterioration in the electrical characteristics of the light-emitting element.

[0052] In contrast, the light-emitting element 1a in FIG. 1B has a contact layer 22 with a high impurity concentration. The contact layer 22 is configured so that the carrier concentration exceeds the crystal defects that occur during ion implantation. This allows the contact layer 22 to maintain low resistance even after ion implantation. The light-emitting element 1a can utilize the contact layer 22 as the current path 7 from the electrode 5 to the light-emitting region 32, thereby improving the electrical characteristics.

[0053] On the other hand, when a contact layer with a high impurity concentration is disposed in the resonator, the contact layer absorbs the resonant light (free carrier absorption), which increases optical loss and reduces the laser output of the light-emitting element. The light-emitting elements 1 and 1a according to the present disclosure are characterized by being able to solve this problem.

[0054] Here, the resonant light in the resonator 6 has one of the antinodes of the standing wave at the boundary surface between the reflecting layer 17 and the cladding layer 23. The antinodes of the standing wave are located at intervals of λ / 2 (λ is the wavelength of the resonant light) from the boundary surface between the reflecting layer 17 and the cladding layer 23. In addition, the nodes of the standing wave are located at positions shifted by λ / 4 from the antinodes of the standing wave.

[0055] The contact layer 22 according to the present disclosure is disposed at the node of the standing wave, for example, at an optical distance of λ / 4 from the interface between the reflective layer 17 and the cladding layer 23.

[0056] The resonator 6 has at least one node of the standing wave at a position xλ / 2+λ / 4 (x is an integer equal to or greater than 0) from the reflective layer 17. The contact layer 22 is not limited to the above example, and may be disposed so as to include at least one node of the standing wave.

[0057] In the light-emitting elements 1 and 1a according to the present disclosure, the contact layer 22 is positioned at a position including a node of the standing wave, thereby minimizing the absorption of resonant light by the contact layer 22 and suppressing optical loss in the resonator 6.

[0058] 3A to 3U are diagrams illustrating the manufacturing process of the light-emitting device 1a according to the first embodiment of the present disclosure. Fig. 3A is a diagram illustrating the lamination and epitaxial growth process. First, a reflective layer 11 is formed on a substrate 2 by epitaxial growth. Furthermore, a cladding layer 12, an active layer 13, a cladding layer 14, a tunnel junction layer 15, a cladding layer 21, a contact layer 22, and a cladding layer 23 are formed on the substrate 2 and the reflective layer 11 in this order by epitaxial growth, thereby forming a laminated semiconductor layer 10.

[0059] FIG. 3B is a diagram showing a step of forming a resist mask for ion implantation. In FIG. 3B, a resist mask 41 is formed on a portion of the surface of the cladding layer 23. FIG. 3C is a diagram showing an ion implantation step. Ions 42 are implanted into the laminated semiconductor layer 10 from above in FIG. 3C. An ion implantation region 31 is formed in the region where the ions 42 are implanted. Furthermore, a light-emitting region 32 is formed in the region where the implantation of the ions 42 is blocked by the resist mask 41. FIG. 3D is a diagram showing a step of removing the resist mask 41. A current confinement structure can be formed in the laminated semiconductor layer 10 by the steps shown in FIGS. 3B to 3D.

[0060] 3E is a diagram showing a step of forming a hard mask for dry etching of the epitaxial growth layer. In FIG. 3E, a hard mask 43 is formed on the surface of the cladding layer 23. The hard mask 43 is made of, for example, SiO ２ FIG. 3F illustrates a resist mask formation step for etching the hard mask 43. In FIG. 3F, a resist mask 44 is formed on the hard mask 43. FIG. 3G illustrates an etching step for the hard mask 43. In FIG. 3G, the hard mask 43 is dry-etched using, for example, a fluorine (F)-based gas. Note that, in FIG. 3G, the hard mask 43 may also be wet-etched using buffered hydrofluoric acid (BHF). This removes the portions of the hard mask 43 that are not covered by the resist mask 44. FIG. 3H illustrates a resist mask 44 removal step. FIG. 3I illustrates a dry etching step for the epitaxial growth layer. In FIG. 3I, the laminated semiconductor layer 10 is dry-etched using, for example, a chlorine (Cl)-based plasma. In FIG. 3I, the cladding layer 23, the contact layer 22, the cladding layer 21, the tunnel junction layer 15, the cladding layer 14, and the active layer 13 are etched, and a portion of the cladding layer 12 is also etched. 3J is a diagram showing a step of removing the hard mask 43. The laminated semiconductor layer 10 can be dry-etched by the steps shown in FIGS.

[0061] FIG. 3K illustrates a resist mask formation step for the upper contact. In FIG. 3K, a resist mask 45 is formed in the center of the cladding layer 23, and a resist mask 46 is formed to cover the side surfaces from the cladding layer 12 to the cladding layer 23 and the surface of the cladding layer 12. That is, the laminated semiconductor layer 10 is covered with the resist masks 45 and 46 except for the outer periphery of the cladding layer 23. FIG. 3L illustrates a wet etching step for the cladding layer 23. In FIG. 3L, the outer periphery of the cladding layer 23 is wet-etched using a mixture of, for example, hydrochloric acid, phosphoric acid, and acetic acid. FIG. 3M illustrates a removal step for the resist masks 45 and 46. Through the steps illustrated in FIGS. 3K to 3M, the contact layer 22 is exposed on the surface of the laminated semiconductor layer 10, and an upper contact A2 that connects to the electrode 5 is formed.

[0062] FIG. 3N is a diagram showing a process for forming the protective film 3. In FIG. 3N, the protective film 3 is formed so as to cover the surface of the laminated semiconductor layer 10 by, for example, a CVD (Chemical Vapor Deposition) film formation method. FIG. 3O is a diagram showing a process for forming a resist mask for dry etching of the protective film 3. In FIG. 3O, a resist mask 47 is formed so as to cover the protective film 3 except for openings in the protective film 3 where the electrodes 4 and 5 are to be disposed. FIG. 3P is a diagram showing a process for dry etching the protective film 3. In FIG. 3P, the protective film 3 is dry-etched using, for example, a fluorine-based gas. FIG. 3Q is a diagram showing a process for removing the resist mask 47. The protective film 3 is formed through the processes shown in FIGS. 3N to 3Q.

[0063] Figure 3R is a diagram showing a resist mask formation step for electrode vapor deposition. In Figure 3R, a resist mask 48 is formed on the protective film 3 except for the portions where the electrodes will be vapor-deposited. Figure 3S is a diagram showing an electrode vapor deposition step. In Figure 3S, electrodes 4 and 5 are formed. Figure 3T is a diagram showing a lift-off step. In the lift-off step of Figure 3T, the resist mask 48 and unnecessary portions of the electrodes 4 and 5 are both removed. The electrodes 4 and 5 can be formed by the steps shown in Figures 3R to 3T.

[0064] Fig. 3U is a diagram showing a process for forming the reflective layer 17. In Fig. 3U, the reflective layer 17 is formed as a film. The light emitting device 1a in Fig. 1B can be fabricated by the processes shown in Figs. 3A to 3U.

[0065] FIG. 4 is a cross-sectional view showing a light-emitting device 100 according to a first comparative example. The light-emitting device 100 differs from the light-emitting device 1a of FIG. 1B in that it includes a buried tunnel junction (BTJ) layer 101 buried in the cladding layer 16. The light-emitting device 100 also includes a contact layer 102 disposed to surround the reflective layer 17. As shown by the current path 103 in FIG. 4, the current supplied from the electrode 5 passes only through the region where the buried tunnel junction layer 101 is disposed. As described above, the light-emitting device 100 can achieve current confinement similar to the light-emitting device 1a. The light-emitting device 100 is also referred to as a BTJ-VCSEL structure.

[0066] 4 , however, has problems of increased processing difficulty and manufacturing costs. To embed the buried tunnel junction layer 101 in the cladding layer 16, an epitaxial regrowth process is required, for example, to form the tunnel junction layer and the cladding layer 16 by epitaxial growth, etch the side surfaces of the tunnel junction layer and the cladding layer 16, and then epitaxially grow the cladding layer 16 again to cover the tunnel junction layer. The light emitting device 100 is disadvantageous for mass production because the manufacturing process includes the costly epitaxial regrowth process.

[0067] 3A to 3U, the light-emitting device 1a according to the present disclosure does not require epitaxial regrowth of the cladding layer 16. In other words, current confinement can be achieved at lower cost and through a simpler process than the light-emitting device 100.

[0068] 5 is a cross-sectional view showing a light-emitting device 100a according to a second comparative example. Like the light-emitting device 1a of FIG. 1B, the light-emitting device 100a achieves current confinement by ion implantation. That is, the light-emitting device 100a can be manufactured at a lower cost than the light-emitting device 100. However, the light-emitting device 100a differs from the light-emitting device 1a of FIG. 1B in that it does not have a contact layer 22 in the cladding layer 16.

[0069] The light emitting device 100a has a current path 103 that supplies current from the electrode 5 to the active layer 13 via the contact layer 102. The current path 103 passes through the surface of the highly resistive cladding layer 16 into which ions are implanted. This requires a high voltage to supply current to the active layer 13, which deteriorates the electrical characteristics of the light emitting device 100a.

[0070] Furthermore, it is technically difficult to avoid increasing the resistance of the surface of the cladding layer 16 and achieve current confinement. The density of crystal defects caused by ion implantation is proportional to the current resistance value of each layer. To achieve current confinement, the density of crystal defects must be equal to or greater than a predetermined threshold. On the other hand, to use the cladding layer 16 and the like as the current path 103, the density of crystal defects must be equal to or less than a predetermined threshold.

[0071] In order to achieve both current confinement in the light emitting device 100a and a low-resistance current path 103, it is necessary to achieve a crystal defect density below a predetermined threshold in the surface portion of the cladding layer 16 (i.e., the portion that becomes the current path 103), and to achieve a crystal defect density above a predetermined threshold in the interior of the cladding layer 16, the cladding layer 14, etc. This is technically difficult.

[0072] 1B can utilize the contact layer 22 in the cladding layer 16 as the current path 7. This allows the light emitting device 1a to achieve both improved electrical characteristics and current confinement.

[0073] The light-emitting element 1a can emit laser light at a lower supply voltage than the light-emitting element 100a. Furthermore, as the emission intensity of the laser light increases, the difference in supply voltage between the light-emitting element 1a and the light-emitting element 100a increases, resulting in a greater improvement in electrical characteristics.

[0074] 6 is a cross-sectional view showing a light emitting device 100b according to a third comparative example. The light emitting device 100b differs from the light emitting device 1a in FIG.

[0075] The contact layer 111 is n-type, similar to the contact layer 22 in FIG. ＋ The light emitting element 100b shown in FIG. 6 is made of InGaAs or the like. InGaAs has the characteristic of being able to maintain low resistance even after ion implantation. The contact layer 111 allows the light emitting element 100b shown in FIG. 6 to achieve both a low-resistance current path 7 and current confinement by ion implantation.

[0076] On the other hand, InGaAs has the problem of absorbing resonant light. Therefore, it is necessary to suppress the absorption of resonant light by, for example, placing the contact layer 111 in a location where the optical field of the resonator 6 is small. However, because the contact layer 111 in Figure 6 is not placed at a node of the standing wave, the absorption of resonant light cannot be suppressed, resulting in large optical loss.

[0077] 6, the contact layer 111 is disposed at the boundary surface with the reflective layer 17 and includes an antinode of the standing wave, which increases the amount of resonant light absorbed by the contact layer 111, resulting in an increase in optical loss in the resonator 6.

[0078] In contrast, in the light emitting device 1a according to the present disclosure, the position of the contact layer 22 is adjusted so as to include a node of the standing wave, thereby making it possible to suppress the optical loss of the resonator 6.

[0079] Fig. 7 is a cross-sectional view showing a light-emitting element 100c according to a fourth comparative example. The light-emitting element 100c differs from the light-emitting element 1a shown in Fig. 1B in that the contact layer 121 is disposed inside the reflective layer 122 on the light-emitting surface A1 side. The contact layer 121 shown in Fig. 7 is disposed at a position shifted from the antinode of the standing wave, thereby reducing the amount of absorption of resonant light.

[0080] The light emitting device 100 c has a current path 123 that supplies current from the electrode 5 to the active layer 13 via the contact layer 121 .

[0081] However, since the current path 123 passes through the inside of the reflective layer 122, which has a band discontinuity structure, the electrical resistance increases, making low-voltage operation difficult. Furthermore, in order to pass a current, it is necessary to implant impurities into the reflective layer 124 below the contact layer 121 in the reflective layer 122. This causes optical absorption of the resonant light in the reflective layer 124, resulting in increased optical loss in the resonator 6.

[0082] In contrast, in the light-emitting device 1a according to the present disclosure, the contact layer 22 is disposed in the cladding layer 16, and current flows from the contact layer 22 to the active layer 13 through the non-ion-implanted region, so that the current path 7 does not pass through the reflective layer 17, and electrical characteristics can be improved compared to the light-emitting device 100c shown in Fig. 7. Furthermore, optical loss in the reflective layer 17 can be suppressed compared to the reflective layer 122.

[0083] As described above, in the light-emitting devices 1 and 1a according to the first embodiment of the present disclosure, the contact layer 22 having a high impurity concentration is disposed in the cladding layer 16. Because the contact layer 22 is made of InGaAs, it can maintain low resistance even after ion implantation, unlike the cladding layers 21 and 23 made of InP. The current path 7 in the light-emitting device 1a according to the first embodiment passes through the contact layer 22 and can reach the active layer 13 without passing through a high-resistance region. This allows the current confinement structure created by ion implantation to be driven at a low voltage, thereby improving power efficiency.

[0084] Furthermore, since the light emitting device 1a achieves current confinement by ion implantation, the manufacturing process can be simplified compared to current confinement using a buried tunnel junction layer, and manufacturing costs can be reduced.

[0085] Furthermore, the position of the contact layer 22 of the light emitting elements 1 and 1a is adjusted so that it is located at a position that includes a node of the standing wave in the resonator 6. This makes it possible to suppress optical loss of the resonant light.

[0086] That is, the light emitting device 1a according to the first embodiment of the present disclosure can reduce manufacturing costs, and can simultaneously achieve stable bulb confinement and improved electrical characteristics.

[0087] Second Embodiment Fig. 8 is a cross-sectional view showing a light-emitting device 1b according to a second embodiment of the present disclosure. The light-emitting device 1b differs from the light-emitting device 1a of Fig. 1B in that the contact layer 22a is made of the same material as the cladding layers 21 and 23. Like the contact layer 22 of Fig. 1B, the contact layer 22a is formed by implanting impurities at a higher concentration than the cladding layers 21 and 23, and therefore has a low current resistance. The contact layer 22a is made of, for example, n ＋ - Made of InP etc.

[0088] The contact layer 22a in FIG. 8 is the n ＋ - Absorption of resonant light can be suppressed more than with a contact layer 22 made of InGaAs or the like. Therefore, the light-emitting element 1b of FIG. 8 has superior optical characteristics to the light-emitting element 1a of FIG. 1B. On the other hand, the contact layer 22 of FIG. 1B has a lower electrical resistance than the contact layer 22a, and therefore has superior electrical characteristics. Therefore, it is desirable to design the material of the contact layer according to the characteristics required of the light-emitting element.

[0089] 9 is a cross-sectional view showing a light-emitting device 1c according to a third embodiment of the present disclosure. The light-emitting device 1c is characterized in that a part or all of the cladding layer 23 is formed of an undoped layer 23a that does not contain impurities.

[0090] By configuring the cladding layer 23 as an undoped layer 23a, light absorption can be suppressed, and the luminous efficiency of the light-emitting element 1c can be improved compared to the light-emitting element 1a in FIG. 1B. Because the cladding layer 23 is not used as the current path 7, the luminous efficiency can be improved without affecting the electrical characteristics of the light-emitting element 1c. Configuring the cladding layer 23 as an undoped layer 23a can be applied to both the first and second embodiments.

[0091] 10 is a cross-sectional view showing a light-emitting device 1d according to a fourth embodiment of the present disclosure. The light-emitting device 1d in FIG. 10 is characterized in that it has a light control member (optical pattern) 51 that controls resonant light at the interface between the cladding layer 23 and the reflective layer 17.

[0092] 11A and 11B are diagrams showing a first configuration example (light control member 51a) of the light control member 51. Fig. 11A is a side view of the light control member 51a. Fig. 11B is a top view of the light control member 51a. The light control member 51a shown in Figs. 11A and 11B is formed of a diffraction grating that performs TM (Transverse Magnetic field) / TE (Transverse Electric field) deflection control on the light emitting region 32.

[0093] 12A and 12B are diagrams showing a second configuration example (light control member 51b) of the light control member 51. Fig. 12A is a side view of the light control member 51b. Fig. 12B is a top view of the light control member 51b. The light control member 51b shown in Figs. 12A and 12B is formed of a diffractive lens that performs beam control such as focusing, refraction, diffraction, or scattering on the light-emitting region 32.

[0094] In addition to the above, the light control member 51 may be composed of a subwavelength grating, an equivalent lens, a metasurface having a microstructure, a concave-convex structure, a trench, or the like. The light-emitting element 1d can arbitrarily control the optical characteristics of resonant light by the light control member 51. The light control member 51 according to the fourth embodiment of the present disclosure can be applied to any of the first to third embodiments.

[0095] Fifth Embodiment Fig. 13 is a cross-sectional view showing a light-emitting element 1e according to a fifth embodiment of the present disclosure. The light-emitting element 1e of Fig. 13 is characterized by having a plurality of active layers 13 and tunnel junction layers 15. Specifically, the laminated semiconductor layer 10a of Fig. 13 is configured by stacking, from the substrate 2 side, a reflective layer 11, a cladding layer 12, an active layer 13a, a cladding layer 14a, a tunnel junction layer 15a, a cladding layer 21a, an active layer 13b, a cladding layer 14b, a tunnel junction layer 15b, a cladding layer 21b, a contact layer 22, and a cladding layer 23 in this order. The light-emitting element 1e is also referred to as a multi-junction structure.

[0096] 13 has two layers each of the active layer 13, the cladding layer 14, the tunnel junction layer 15, and the cladding layer 21. However, the light emitting element 1e may have a configuration having three or more layers each of these semiconductor layers.

[0097] The light-emitting element 1e has a plurality of active layers 13, which allows for increased laser output. Furthermore, the plurality of tunnel junction layers 15 (and cladding layers 14 and 21) allows for uniform supply of electric charges to the plurality of active layers 13. This allows the light-emitting element 1e to emit high-output laser light. The stacked structure according to the fifth embodiment of the present disclosure can be applied to any of the first to fourth embodiments.

[0098] Sixth Embodiment Fig. 14 is a cross-sectional view showing a light-emitting device 1f according to a sixth embodiment of the present disclosure. The light-emitting device 1a in Fig. 1B has a cladding layer 12 containing an InP-based material stacked on a substrate 2 and a reflective layer 11 containing an InP material. In contrast, the light-emitting device 1f in Fig. 14 differs in that a substrate 2a and a reflective layer 11a containing a GaAs-based material are bonded to a laminated semiconductor layer 10. The substrate 2a is, for example, a GaAs substrate. The reflective layer 11a is made of, for example, GaAs / AlGaAs.

[0099] The reflective layer 11a made of GaAs / AlGaAs or the like has higher heat dissipation properties than the reflective layer 11 in Fig. 1B made of InP / AlGaInAs or the like. The reflective layer 11a can suppress heat generation in the light-emitting element 1f in Fig. 14. The substrate 2a and the reflective layer 11a according to the sixth embodiment of the present disclosure can be applied to any of the first to fifth embodiments.

[0100] Seventh Embodiment Fig. 15 is a cross-sectional view showing a light-emitting device 1g according to a seventh embodiment of the present disclosure. The light-emitting device 1g of Fig. 15 is characterized in that the active layer 13c has a quantum dot structure. More specifically, quantum dots, which are multiple dot-shaped crystals with a small band gap, are arranged in the surface direction in the active layer 13c. Furthermore, a barrier with a large band gap is disposed between adjacent quantum dots. The active layer 13c is made of, for example, InAs.

[0101] The active layer 13c has a feature that the conductivity in the plane direction is low because the barriers arranged between the quantum dots restrict the flow of current injected into the quantum dots. This prevents current from flowing to the sidewalls of the active layer 13c (e.g., the protective film 3), and prevents a decrease in laser output. The quantum dot structure according to the seventh embodiment of the present disclosure can be applied to any of the first to sixth embodiments.

[0102] 16 is a cross-sectional view showing a light-emitting element 1 h according to an eighth embodiment of the present disclosure. The light-emitting element 1 h in FIG. 16 is characterized in that it has a diffusion region 61 formed by diffusing the material of the electrode 5 a in the cladding layer 23 b and the contact layer 22.

[0103] The electrode 5a is made of, for example, AuGe, etc. During ohmic alloying, the electrode 5a diffuses AuGe into the cladding layer 23b to form a diffusion region (AuGe diffusion region) 61 that reaches the contact layer 22. The electrode 5a is electrically connected to the contact layer 22 via the diffusion region 61.

[0104] The light-emitting element 1h can simplify the manufacturing process because it is not necessary to etch the cladding layer 23b to expose the contact layer 22. Specifically, the light-emitting element 1h can omit the steps of Figures 3K to 3M. The electrode 5a according to the eighth embodiment of the present disclosure can be applied to any of the first to seventh embodiments.

[0105] Ninth Embodiment Fig. 17 is a plan view of a light-emitting element 1i according to a ninth embodiment of the present disclosure. Fig. 18 is a cross-sectional view showing the light-emitting element 1i according to the ninth embodiment of the present disclosure. The light-emitting element 1i in Fig. 17 is characterized in that it has a plurality of light-emitting portions 71 arranged along the light emission surface.

[0106] Fig. 18 is a cross-sectional view taken along line BB' in Fig. 17. In the example of Fig. 18, the light-emitting element 1i has light-emitting portions 71a and 71b. Each of the light-emitting portions 71a and 71b has a light-emitting region 32, and also has a reflective layer 11, a cladding layer 12, an active layer 13, a cladding layer 14, a tunnel junction layer 15, a cladding layer 21, a contact layer 22, a cladding layer 23, and a reflective layer 17 within the light-emitting region 32.

[0107] 17, the light-emitting element 1i can be configured with a plurality of light-emitting portions 71. The plurality of light-emitting portions 71 according to the ninth embodiment of the present disclosure can be applied to any of the first to eighth embodiments.

[0108] Tenth Embodiment Fig. 19 is a block diagram showing an example configuration of a distance measuring system 80 according to a tenth embodiment of the present disclosure. The distance measuring system 80 in Fig. 19 measures the distance to an arbitrary subject S by irradiating the subject S with light and receiving the reflected light. The distance measuring system 80 includes a light emitting device 81, a driving unit 82, a power supply circuit 83, a light emitting side optical system 84, a light receiving side optical system 85, a light receiving device 86, a signal processing unit 87, a control unit 88, and a temperature detection unit 89.

[0109] The light emitting device 81 emits light from a plurality of light sources. The light emitting device 81 has a light emitting element 1 (or 1a to 1i) according to the present disclosure as each light source. The light emitting device 81 is configured such that a plurality of light emitting elements (or light emitting sections 71) are arranged in a predetermined pattern, such as a matrix.

[0110] The driving unit 82 is configured to have a power supply circuit 83 for driving the light emitting device 81. The power supply circuit 83 generates a power supply voltage for the driving unit 82 based on an input voltage from, for example, a battery (not shown) or the like provided in the distance measuring system 80. The driving unit 82 drives the light emitting device 81 based on the power supply voltage.

[0111] Light emitted from the light-emitting device 81 is irradiated onto a subject (object) S, which is the distance measurement target, via a light-emitting side optical system 84. The light thus irradiated is reflected from the subject S and enters the light-receiving surface of a light-receiving device 86 via a light-receiving side optical system 85.

[0112] The light receiving device 86 is a light receiving element such as a CCD (Charge Coupled Device) sensor or a CMOS (Complementary Metal Oxide Semiconductor) sensor, and receives reflected light from the subject S that enters through the light receiving side optical system 85 as described above, converts it into an electrical signal, and outputs it.

[0113] The light receiving device 86 performs processes such as CDS (Correlated Double Sampling) and AGC (Automatic Gain Control) on the electrical signal obtained by photoelectrically converting the received light, and then performs A / D (Analog / Digital) conversion on the electrical signal, and outputs the resulting digital data to a signal processing unit 87 at a subsequent stage.

[0114] Furthermore, the light receiving device 86 of this example outputs a frame synchronization signal to the driving unit 82. This enables the driving unit 82 to cause the light emitting element of the light emitting device 81 to emit light at a timing according to the frame period of the light receiving device 86.

[0115] The signal processing unit 87 is configured as a signal processor, for example, a DSP (Digital Signal Processor), etc. The signal processing unit 87 performs various signal processes on the digital signal input from the light receiving device 86.

[0116] The control unit 88 is configured with, for example, a microcomputer having a CPU (Central Processing Unit), ROM (Read Only Memory), RAM (Random Access Memory), etc., or an information processing device such as a DSP, and controls the drive unit 82 for controlling the light-emitting operation of the light-emitting device 81, and controls the light-receiving operation of the light-receiving device 86.

[0117] The control unit 88 has a function as a distance measurement unit 88a. The distance measurement unit 88a measures the distance to the subject S based on a signal input via the signal processing unit 87 (i.e., a signal obtained by receiving reflected light from the subject S). The distance measurement unit 88a in this example measures the distance to each part of the subject S in order to be able to identify the three-dimensional shape of the subject S. Note that the specific distance measurement method in the distance measurement system 80 will be described again later.

[0118] The temperature detection unit 89 detects the temperature of the light-emitting device 81. The temperature detection unit 89 may be configured to detect temperature using, for example, a diode. In this example, information about the temperature detected by the temperature detection unit 89 is supplied to the drive unit 82, which enables the drive unit 82 to drive the light-emitting device 81 based on the temperature information.

[0119] The distance measurement method used in the distance measurement system 80 may be, for example, a STL (Structured Light) method or a ToF (Time of Flight) method.

[0120] The STL method is a method for measuring distance based on an image of a subject S illuminated with light having a predetermined light / dark pattern, such as a dot pattern or a grid pattern.

[0121] Fig. 20A is an explanatory diagram of the STL method. In the STL method, pattern light Lp having a dot pattern such as that shown in Fig. 20A is irradiated onto a subject S. The pattern light Lp is divided into a plurality of blocks BL, and a different dot pattern is assigned to each block BL (dot patterns are arranged not to overlap between blocks BL).

[0122] 20B is an explanatory diagram of the distance measurement principle of the STL method. In this example, a wall W and a box BX placed in front of it are considered as the subject S, and pattern light Lp is irradiated onto the subject S. "G" in the diagram schematically represents the angle of view of the light receiving device 86.

[0123] In addition, "BLn" in the figure denotes the light of a certain block BL in the pattern light Lp, and "dn" denotes the dot pattern of the block BLn projected on the light-receiving image by the light-receiving device 86.

[0124] Here, if there is no box BX in front of the wall W, the dot pattern of the block BLn is projected at the position "dn'" in the figure in the received light image. In other words, the position at which the pattern of the block BLn is projected in the received light image differs depending on whether the box BX is present or not, and specifically, the pattern is distorted.

[0125] The STL method utilizes the fact that the irradiated pattern is distorted by the object shape of the subject S to determine the shape and depth of the subject S. Specifically, this method determines the shape and depth of the subject S from the way the pattern is distorted.

[0126] When the STL system is employed, for example, a global shutter type IR (Infrared) light receiving unit is used as the light receiving device 86. In the case of the STL system, the distance measuring unit 88a controls the drive unit 82 so that the light emitting device 81 emits pattern light, detects distortion of the pattern in the image signal obtained via the signal processing unit 87, and calculates the distance based on the distortion of the pattern.

[0127] Next, the ToF method is a method for measuring the distance to an object by detecting the time of flight (time difference) of light emitted from the light-emitting device 81, reflected by the object, and reaching the light-receiving device 86.

[0128] When the so-called direct ToF (dTOF) method is adopted as the ToF method, a SPAD (Single Photon Avalanche Diode) is used as the light receiving device 86, and the light emitting device 81 is pulse-driven. In this case, the distance measuring unit 88a calculates the time difference between light emission and reception of light emitted from the light emitting device 81 and received by the light receiving device 86 based on a signal input via the signal processing unit 87, and calculates the distance to each part of the subject S based on the time difference and the speed of light.

[0129] When the so-called indirect ToF (iTOF) method (phase difference method) is adopted as the ToF method, a light receiving unit capable of receiving, for example, IR light is used as the light receiving device 86 .

[0130] By using the light emitting element 1 (or 1a to 1i) according to the present disclosure as the light emitting device 81, the cost of the distance measuring system 80 can be reduced and power consumption can be suppressed.

[0131] 21 is a cross-sectional view of a distance measuring system 80a according to an eleventh embodiment of the present disclosure. The distance measuring system 80a in FIG. 21 is characterized by having a ToF module configuration in which a light emitting element 1j and a light receiving element 90 are integrated on a substrate 2b.

[0132] The substrate 2b is, for example, a Si (silicon) substrate. The light receiving element 90 is generally disposed on a silicon substrate. For this reason, in this embodiment, by using a silicon substrate as the substrate (support substrate) 2b of the light emitting element 1j, it becomes possible to dispose the light emitting element 1j and the light receiving element 90 on the same silicon substrate. A light shielding member 91 is disposed at the boundary between the arrangement area of ​​the light emitting element 1j and the arrangement area of ​​the light receiving element 90 so that the light emitted from the light emitting element 1j is not directly received by the light receiving element 90. This allows the light emitting element 1j and the light receiving element 90 to be integrated into a single chip, thereby achieving miniaturization and cost reduction.

[0133] A light-receiving element 90 according to the eleventh embodiment can be used, for example, as the light-receiving device 86 in FIG. 19 . The light-receiving element 90 has a photoelectric conversion element (PD: photodiode) 92 and an electrode 93. The photoelectric conversion element 92 receives light and accumulates charge according to the amount of light, and is made of, for example, SiGe or the like, which has long-distance sensitivity. The electrode 93 is used, for example, as an electrode of a transistor that transfers the charge accumulated in the photoelectric conversion element 92.

[0134] Furthermore, the distance measuring system 80a according to the eleventh embodiment may integrate any circuit such as a signal processing circuit in addition to the light emitting element 1j and the light receiving element 90. Furthermore, the distance measuring system 80a according to the eleventh embodiment can be applied to any of the light emitting elements 1 to 1i according to the first to tenth embodiments.

[0135] (Application Examples) The technology according to the present disclosure (the present technology) can be applied to various products. 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.

[0136] FIG. 22 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.

[0137] The vehicle control system 12000 includes a plurality of electronic control units connected via a communication network 12001. In the example shown in Fig. 22, the vehicle control system 12000 includes a drive system control unit 12010, a body system control unit 12020, an outside-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.

[0138] 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, and a braking device for generating a braking force of the vehicle.

[0139] 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 can 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.

[0140] The outside-vehicle information detection unit 12030 detects information outside the vehicle equipped with the vehicle control system 12000. For example, an imaging unit 12031 is connected to the outside-vehicle information detection unit 12030. The outside-vehicle information detection unit 12030 causes the imaging unit 12031 to capture images outside the vehicle and receives the captured images. The outside-vehicle information detection unit 12030 may perform object detection processing or distance detection processing for people, cars, obstacles, signs, characters on the road surface, etc. based on the received images.

[0141] The imaging unit 12031 is an optical sensor that receives light and outputs an electrical signal corresponding to the amount of light received. The imaging unit 12031 can output the electrical signal as an image or as distance measurement information. The light received by the imaging unit 12031 may be visible light or invisible light such as infrared light.

[0142] 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.

[0143] 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 drive system 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 vehicle collision avoidance or impact mitigation, following driving based on the inter-vehicle distance, vehicle speed maintenance driving, vehicle collision warning, vehicle lane departure warning, etc.

[0144] 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.

[0145] Furthermore, the microcomputer 12051 can output a control command to the body system control unit 12020 based on the information outside 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 aimed at preventing glare, such as switching from high beams to low beams.

[0146] 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 the passengers of the vehicle or the outside of the vehicle of information. In the example of Fig. 22, the output devices are exemplified by an audio speaker 12061, a display unit 12062, and an instrument panel 12063. The display unit 12062 may include, for example, at least one of an on-board display and a head-up display.

[0147] FIG. 23 is a diagram showing an example of the installation position of the imaging unit 12031.

[0148] In FIG. 23, a vehicle 12100 has imaging units 12101, 12102, 12103, 12104, and 12105 as the imaging unit 12031.

[0149] The imaging units 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 the vehicle 12100. The imaging unit 12101 provided on the front nose and the imaging unit 12105 provided on the top of the windshield inside the vehicle cabin mainly acquire images of the front of the vehicle 12100. The imaging units 12102 and 12103 provided on the side mirrors mainly acquire images of the sides of the vehicle 12100. The imaging unit 12104 provided on the rear bumper or back door mainly acquires images of the rear of the vehicle 12100. The forward images acquired by the imaging units 12101 and 12105 are mainly used to detect preceding vehicles, pedestrians, obstacles, traffic lights, traffic signs, lanes, etc.

[0150] 23 shows an example of the imaging ranges of the imaging units 12101 to 12104. Imaging range 12111 indicates the imaging range of the imaging unit 12101 provided on the front nose, imaging ranges 12112 and 12113 indicate the imaging ranges of the imaging units 12102 and 12103 provided on the side mirrors, respectively, and imaging range 12114 indicates the imaging range of the imaging unit 12104 provided on the rear bumper or back door. For example, by overlaying the image data captured by the imaging units 12101 to 12104, an overhead image of the vehicle 12100 viewed from above can be obtained.

[0151] At least one of the image capturing units 12101 to 12104 may have a function of acquiring distance information. For example, at least one of the image capturing units 12101 to 12104 may be a stereo camera made up of multiple image capturing elements, or may be an image capturing element having pixels for phase difference detection.

[0152] For example, based on the distance information obtained from the imaging units 12101 to 12104, the microcomputer 12051 can calculate the distance to each three-dimensional object within the imaging ranges 12111 to 12114 and the change in this distance over time (relative speed with respect to the vehicle 12100), thereby extracting as a preceding vehicle, in particular, 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 (e.g., 0 km / h or higher). 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 autonomous driving, which runs autonomously without relying on driver operation.

[0153] 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 information obtained from the imaging units 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 a collision risk that indicates the 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 drive system control unit 12010.

[0154] At least one of the image capturing units 12101 to 12104 may be an infrared camera that detects infrared rays. For example, the microcomputer 12051 can recognize a pedestrian by determining whether a pedestrian is present in the images captured by the image capturing units 12101 to 12104. Such pedestrian recognition is performed, for example, by extracting feature points from the images captured by the image capturing units 12101 to 12104 as infrared cameras and performing pattern matching on a series of feature points that indicate the outline of an object to determine whether the object is a pedestrian. When the microcomputer 12051 determines that a pedestrian is present in the images captured by the image capturing units 12101 to 12104 and recognizes the pedestrian, the audio / image output unit 12052 controls the display unit 12062 to superimpose a rectangular outline on the recognized pedestrian for emphasis. The audio / image output unit 12052 may also control the display unit 12062 to display an icon or the like indicating the pedestrian at a desired position.

[0155] The above describes an example of a vehicle control system to which the technology according to the present disclosure can be applied. The technology according to the present disclosure can be applied to, for example, the imaging unit 12031 among the above-described configurations. Specifically, the light-emitting element 1 according to the present disclosure may be provided together with the imaging unit 12031. By applying the technology according to the present disclosure to the imaging unit 12031, it is possible to reduce the manufacturing cost of the imaging unit 12031 of the vehicle 12100 and reduce the power consumption of the imaging unit 12031.

[0156] The present technology can be configured as follows: (1) A light-emitting device comprising: a laminated semiconductor layer having an active layer that performs surface emission; and a first reflective layer that reflects light emitted in the active layer and propagating in a light emission direction of the laminated semiconductor layer, wherein the laminated semiconductor layer has: a second reflective layer that reflects light emitted in the active layer and propagating in a direction opposite to the light emission direction of the laminated semiconductor layer and that resonates the light emitted in the active layer between the first reflective layer and the laminated semiconductor layer; a first cladding layer disposed between the active layer and the first reflective layer; a contact layer disposed inside the first cladding layer and that passes a current to the active layer; and a second cladding layer disposed between the active layer and the second reflective layer. (2) The light-emitting device according to (1), wherein the first cladding layer has: a third cladding layer disposed closer to the first reflective layer than the contact layer; and a fourth cladding layer disposed closer to the active layer than the contact layer. (3) The light-emitting device according to (2), wherein the first reflective layer and the second reflective layer constitute at least a part of a resonator that resonates light generated in the active layer, and the contact layer is disposed at a node of a standing wave of light resonated in the resonator. (4) The light-emitting device according to (3), wherein the resonator resonates light of a predetermined wavelength λ and generates a node of the standing wave at a position xλ / 2+λ / 4 (x is an integer equal to or greater than 0) from the first reflective layer, and the contact layer is disposed at a position of at least one of a plurality of nodes of the standing wave. (5) The light-emitting device according to any one of (2) to (4), wherein the contact layer has a higher impurity concentration than the first cladding layer. (6) The light-emitting device according to (5), wherein the contact layer includes a material having a smaller band gap than the first cladding layer. (7) The light-emitting device according to (6), wherein the first cladding layer contains InP, and the contact layer contains at least one material selected from the group consisting of InGaAs, InGaAsP, and AlGaInAs. (8) The light-emitting device according to (5), wherein the contact layer and the first cladding layer contain InP.(9) The light-emitting device according to any one of (2) to (8), wherein the active layer, the first cladding layer, and the contact layer have a current confinement structure formed by ion implantation, and the contact layer is made of a compound semiconductor material that does not cause high resistance due to ion implantation. (10) The light-emitting device according to any one of (2) to (9), wherein the third cladding layer is an undoped layer. (11) The light-emitting device according to any one of (1) to (10), wherein an optical control member that controls light generated in the active layer is provided at an interface between the first cladding layer and the first reflective layer. (12) The light-emitting device according to (11), wherein the optical control member includes at least one of a diffraction grating, a diffractive lens, a subwavelength grating, an equivalent lens, a metasurface, or a trench. (13) The light-emitting device according to any one of (1) to (12), wherein the laminated semiconductor layer includes a plurality of the active layers and a plurality of tunnel junction layers that inject current into the plurality of active layers. (14) The light-emitting device according to any one of (1) to (13), wherein the second reflective layer contains InP and AlGaInAs. (15) The light-emitting device according to any one of (1) to (13), wherein the second reflective layer contains GaAs and AlGaAs. (16) The light-emitting device according to any one of (1) to (15), wherein the active layer has a quantum well structure or a quantum dot structure. (17) The light-emitting device according to any one of (1) to (16), further comprising an electrode for passing a current through the active layer, wherein the electrode contains AuGe, and the first cladding layer and the contact layer include a diffusion region of the AuGe. (18) The light-emitting element according to any one of (1) to (17), wherein the laminated semiconductor layer has a plurality of light-emitting regions each arranged along a light-emitting surface and each having the active layer, the first reflective layer, the second reflective layer, the first cladding layer, the contact layer, and the second cladding layer.(19) A ranging system comprising: a light-emitting element; and a ranging unit that measures a distance to an object to be measured based on emitted light from the light-emitting element and reflected light of the emitted light reflected by the object to be measured, wherein the light-emitting element comprises: a laminated semiconductor layer having an active layer that performs surface emission; and a first reflective layer that reflects light emitted in the active layer and propagating in the light emission direction of the laminated semiconductor layer, and the laminated semiconductor layer comprises: a second reflective layer that reflects light emitted in the active layer and propagating in the opposite direction to the light emission direction of the laminated semiconductor layer and resonates the light emitted in the active layer between the first reflective layer and the laminated semiconductor layer, a first cladding layer arranged between the active layer and the first reflective layer, a contact layer arranged inside the first cladding layer and that passes a current to the active layer, and a second cladding layer arranged between the active layer and the second reflective layer. (20) The distance measuring system according to (19), comprising: a light receiving element that receives the reflected light; and a support substrate that supports the light emitting element and the light receiving element.

[0157] The aspects of the present disclosure are not limited to the individual embodiments described above, but include various modifications that may be conceived by those skilled in the art, and the effects of the present disclosure are not limited to the above-described contents. In other words, various additions, modifications, and partial deletions are possible within the scope of the conceptual idea and spirit of the present disclosure, which is derived from the contents defined in the claims and their equivalents.

[0158] 1, 1a, 1b, 1c, 1d, 1e, 1f, 1g, 1h, 1i, 1j, 100, 100a, 100b, 100c Light emitting element, 2, 2a, 2b Substrate, 3 Protective film, 4, 5, 5a, 93 Electrode, 6 Resonator, 7, 103, 123 Current path, 10, 10a Laminated semiconductor layer, 11, 11a, 17, 122, 124 Reflective layer, 12, 14, 14a, 14b, 16, 21, 21a, 21b, 23, 23b Cladding layer, 13, 13a, 13b, 13c Active layer, 15, 15a, 15b Tunnel junction layer, 22, 22a, 102, 111, 121 Contact layer, 23a Undoped layer, 31 Ion implantation region, 32 Light-emitting region, 41, 44, 45, 46, 47, 48: resist mask, 42: ions, 43: hard mask, 51, 51a, 51b: light control member, 61: diffusion region, 71, 71a, 71b: light-emitting section, 80, 80a: distance measurement system, 81: light-emitting device, 82: drive section, 83: power supply circuit, 84: light-emitting side optical system, 85: light-receiving side optical system, 86: light-receiving device, 87: signal processing section, 88: control section, 88a: distance measurement section, 89: temperature detection section, 90: light-receiving element, 91: light-shielding member, 92: photoelectric conversion element, 101: buried tunnel junction layer

Claims

1. A light-emitting device comprising: a laminated semiconductor layer having an active layer that emits surface light; and a first reflective layer that reflects light emitted in the active layer and propagating in the light emission direction of the laminated semiconductor layer, wherein the laminated semiconductor layer has: a second reflective layer that reflects light emitted in the active layer and propagating in the opposite direction to the light emission direction of the laminated semiconductor layer, and causes the light emitted in the active layer to resonate between it and the first reflective layer; a first cladding layer disposed between the active layer and the first reflective layer; a contact layer disposed inside the first cladding layer and that passes current to the active layer; and a second cladding layer disposed between the active layer and the second reflective layer.

2. The light-emitting element according to claim 1, wherein the first cladding layer has a third cladding layer disposed closer to the first reflecting layer than the contact layer, and a fourth cladding layer disposed closer to the active layer than the contact layer.

3. The light-emitting device according to claim 2, wherein the first reflective layer and the second reflective layer constitute at least a part of a resonator that resonates light generated in the active layer, and the contact layer is disposed at a node of a standing wave of light resonated in the resonator.

4. The light-emitting element according to claim 3, wherein the resonator resonates light of a predetermined wavelength λ and generates a node of the standing wave at a position xλ / 2+λ / 4 (x is an integer equal to or greater than 0) from the first reflective layer, and the contact layer is disposed at the position of at least one of the multiple nodes of the standing wave.

5. The light-emitting device according to claim 2, wherein the contact layer has a higher impurity concentration than the first cladding layer.

6. The light-emitting device according to claim 5, wherein the contact layer contains a material having a smaller band gap than the first cladding layer.

7. The light-emitting device according to claim 6, wherein the first cladding layer includes InP, and the contact layer includes at least one material selected from the group consisting of InGaAs, InGaAsP, and AlGaInAs.

8. The light-emitting device according to claim 5, wherein the contact layer and the first cladding layer contain InP.

9. The light-emitting device according to claim 2, wherein the active layer, the first cladding layer, and the contact layer have a current confinement structure formed by ion implantation, and the contact layer is made of a compound semiconductor material that does not cause high resistance due to ion implantation.

10. The light-emitting device according to claim 2, wherein the third cladding layer is an undoped layer.

11. The light-emitting device according to claim 1, further comprising a light control member at the interface between said first cladding layer and said first reflecting layer, for controlling light generated in said active layer.

12. The light-emitting element according to claim 11, wherein the light control member includes at least one of a diffraction grating, a diffractive lens, a sub-wavelength grating, an equivalent lens, a metasurface, or a trench.

13. The light-emitting element according to claim 1, wherein the laminated semiconductor layer comprises: a plurality of the active layers; and a plurality of tunnel junction layers that inject current into the plurality of active layers.

14. The light-emitting device according to claim 1, wherein the second reflective layer includes InP and AlGaInAs.

15. The light-emitting device according to claim 1, wherein the second reflective layer includes GaAs and AlGaAs.

16. The light-emitting device according to claim 1, wherein the active layer has a quantum well structure or a quantum dot structure.

17. The light-emitting device according to claim 1, further comprising an electrode for passing a current through the active layer, the electrode including AuGe, and the first cladding layer and the contact layer including a diffusion region of the AuGe.

18. The light-emitting device according to claim 1, wherein the laminated semiconductor layer has a plurality of light-emitting regions each arranged along the light-emitting surface and each having the active layer, the first reflective layer, the second reflective layer, the first cladding layer, the contact layer, and the second cladding layer.

19. A ranging system comprising: a light-emitting element; and a ranging unit that measures the distance to an object to be measured based on light emitted from the light-emitting element and light reflected from the object to be measured, wherein the light-emitting element comprises: a laminated semiconductor layer having an active layer that performs surface emission; and a first reflective layer that reflects light emitted from the active layer and propagating in the light emission direction of the laminated semiconductor layer, and the laminated semiconductor layer comprises: a second reflective layer that reflects light emitted from the active layer and propagating in the opposite direction to the light emission direction of the laminated semiconductor layer, and resonates the light emitted from the active layer between it and the first reflective layer; a first cladding layer arranged between the active layer and the first reflective layer; a contact layer arranged inside the first cladding layer and that passes a current to the active layer; and a second cladding layer arranged between the active layer and the second reflective layer.

20. The distance measuring system according to claim 19, comprising: a light receiving element that receives the reflected light; and a support substrate that supports the light emitting element and the light receiving element.

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