Light-emitting device

Abstract

[Problem] To provide a highly reliable light-emitting device in which a photodiode provided in a vertical cavity can efficiently detect light of a predetermined wavelength. [Solution] This light-emitting device includes a substrate containing a Group III-V element or a Group IV element, a first reflecting portion provided on the substrate, a second reflecting portion provided above the first reflecting portion, a first semiconductor layer of a first conductivity type and a second semiconductor layer of a second conductivity type provided between the first reflecting portion and the second reflecting portion, an active layer provided between the first semiconductor layer and the second semiconductor layer and configured to generate light of a first wavelength by application of power to the first and second semiconductor layers, and a photodiode layer provided in the first reflecting portion, containing a Group IV element, and configured to photoelectrically convert the light of the first wavelength to generate charges.

Description

Light-emitting device

[0001] The present disclosure relates to a light-emitting device.

[0002] An SMI (Self-Mixing Interference)-VCSEL in which a photodiode is provided inside a vertical cavity surface emitting laser (VCSEL (Vertical Cavity Surface Emitting Laser)) has been developed.

[0003] Japanese National Publication No. 2021-528863, Japanese National Publication No. 2011-520280

[0004] In an SMI-VCSEL using a GaAs substrate, it has been difficult for the photodiode provided therein to satisfactorily detect light of a relatively long wavelength in the SWIR (Short-Wavelength InfraRed) band.

[0005] Accordingly, the present disclosure provides a highly reliable light-emitting device in which a photodiode provided in a vertical cavity can efficiently detect light of a predetermined wavelength.

[0006] A light-emitting device according to one aspect of the present disclosure includes: a substrate containing a group III-V element or a group IV element; a first reflecting portion provided on the substrate; a second reflecting portion provided above the first reflecting portion; a first semiconductor layer of a first conductivity type and a second semiconductor layer of a second conductivity type provided between the first reflecting portion and the second reflecting portion; an active layer provided between the first semiconductor layer and the second semiconductor layer, the active layer generating light of a first wavelength by applying power to the first and second semiconductor layers; and a photodiode layer provided in the first reflecting portion, the photodiode layer containing a group IV element and generating electric charge by photoelectrically converting the light of the first wavelength.

[0007] The first reflecting portion includes a first reflective layer containing a group III-V element layer of the first conductivity type and a second reflective layer containing a group III-V element layer of the second conductivity type, and the photodiode layer is provided between the first reflective layer and the second reflective layer.

[0008] The substrate is a substrate containing GaAs (gallium arsenide) or a substrate containing Ge (germanium).

[0009] The photodiode layer is a layer containing Ge.

[0010] The first and second semiconductor layers are semiconductor layers containing group III-V elements, and the second reflective portion is a laminate of multiple semiconductor layers containing group III-V elements.

[0011] The first and second semiconductor layers are semiconductor layers containing GaAs, and the second reflective portion is a laminate of multiple GaAs layers and multiple AlGaAs layers.

[0012] The first and second semiconductor layers are semiconductor layers containing InP.

[0013] The second reflective section is a laminate of multiple dielectric layers.

[0014] The substrate, the first reflector, and the photodiode layer contain GaAs or Ge, and there is a bonding surface between the first reflector and the first semiconductor layer.

[0015] The device further comprises a first electrode electrically connected to a first semiconductor layer, a second electrode electrically connected to a second semiconductor layer, and a third electrode electrically connected to a first reflective layer.

[0016] The second reflective section includes an uneven layer having an uneven shape on the light-emitting surface from which light from the active layer is emitted.

[0017] The device further comprises a constricted layer including a conductive region provided between the second reflective portion and the second semiconductor layer, and an insulating region provided around the conductive region.

[0018] The device further comprises a third semiconductor layer provided on the second semiconductor layer between the second reflective portion and the second semiconductor layer, having a higher impurity concentration of the second conductivity type than the second semiconductor layer, and a fourth semiconductor layer of the first conductivity type provided on the third semiconductor layer, forming a tunnel junction with the third semiconductor layer.

[0019] The device further comprises a fifth semiconductor layer provided on a fourth semiconductor layer, the fifth semiconductor layer including a conductive region sandwiched between a first reflective portion and a second reflective portion, and an impurity implant region provided around the conductive region.

[0020] Light from the active layer is emitted from the substrate side.

[0021] The photodiode layer is an avalanche photodiode.

[0022] The photodiode layer includes a photoelectric conversion layer that converts light of a first wavelength into electricity to generate an electric charge, and a multiplier layer that multiplies the charge using an avalanche mechanism.

[0023] The photodiode layer is provided between the photoelectric conversion layer and the multiplier layer, and further includes a transition layer that transfers the charge generated in the photoelectric conversion layer to the multiplier layer.

[0024] Figure 4 is a cross-sectional view showing an example of the configuration of a light-emitting device according to the first embodiment. Figure 5 is a cross-sectional view showing an example of a method for manufacturing a light-emitting device according to the first embodiment. Figure 6 is a cross-sectional view showing an example of a method for manufacturing a light-emitting device, following Figure 4. Figure 7 is a cross-sectional view showing an example of a method for manufacturing a light-emitting device, following Figure 8. Figure 8 is a cross-sectional view showing an example of the configuration of a light-emitting device according to the second embodiment. Figure 9 is a cross-sectional view showing an example of the configuration of a light-emitting device according to the third embodiment. Figure 10 is a cross-sectional view showing an example of the configuration of a light-emitting device, following Figure 4. Figure 11 is a cross-sectional view showing an example of a method for manufacturing a light-emitting device, following Figure 5. Figure 11 is a cross-sectional view showing an example of a method for manufacturing a light-emitting device, following Figure 6. Figure 11 is a cross-sectional view showing an example of a method for manufacturing a light-emitting device, following Figure 7. Figure 11 is a cross-sectional view showing an example of a method for manufacturing a light-emitting device, following Figure 8. Figure 11 is a cross-sectional view showing an example of the configuration of a light-emitting device according to the second embodiment. Figure 11 is a cross-sectional view showing an example of the configuration of a light-emitting device according to the third embodiment. Figure 11 is a cross-sectional view showing an example of the configuration of a light-emitting device according to the fourth embodiment. Figure 11 is a cross-sectional view showing an example of the configuration of a light-emitting device according to the fifth embodiment. Figure 11 is a cross-sectional view showing an example of the configuration of a light-emitting device according to the sixth embodiment. Figure 11 is a cross-sectional view showing an example of the configuration of a light-emitting device according to the seventh embodiment. Figure 11 is a cross-sectional view showing an example of the configuration of a light-emitting device according to the eighth embodiment. Figure 11 This is an explanatory diagram showing an example of the installation location of the external information detection unit and the imaging unit.

[0025] The following describes specific embodiments of this technology with reference to the drawings. The drawings are schematic or conceptual, and the proportions of each part may not necessarily be the same as those of actual objects. In the specification and drawings, elements similar to those described above are denoted by the same reference numerals with respect to previously shown drawings, and detailed explanations are omitted as appropriate.

[0026] (First Embodiment) Figure 1 is a cross-sectional view showing an example of the configuration of a light-emitting device 1 according to the first embodiment. The light-emitting device 1 comprises a substrate 10, a first reflector 20, a photodiode layer 120, a first semiconductor layer 30, an active layer 40, a second semiconductor layer 50, constriction layers 60, 80, a second reflector 90, a first electrode 100, a second electrode 110, a third electrode 115, and an insulating film 105.

[0027] The light-emitting device 1 is a semiconductor light-emitting device such as an SMI-VCSEL incorporating a photodiode. The light-emitting device 1 emits light by applying power between the first electrode 100 and the second electrode 110, thereby injecting electrons and holes from the first and second semiconductor layers 30 and 50 into the active layer 40, and recombining the electrons and holes in the active layer 40. The light is reflected and resonates between the first reflector 20 and the second reflector 90, and is emitted as laser light from the second reflector 90 side. At this time, the photodiode layer 120 is biased between the first electrode 100 and the third electrode 115, and converts the light from the active layer 40 into photoelectric energy, generating an electric charge. The charge generated in the photodiode layer 120 is detected externally via the first electrode 100 or the third electrode 115.

[0028] The substrate 10 is a semiconductor substrate containing group III-V elements or group IV elements. For example, the substrate 10 is a substrate containing n-type GaAs or a substrate containing n-type Ge.

[0029] The first reflector 20 is a so-called DBR (Distributed Bragg Reflector) and is constructed by alternately stacking multiple materials with different refractive indices. For example, the first reflector 20 has a stacked structure of multiple epitaxially grown semiconductor materials. The first reflector 20 includes an n-type first reflective layer 20a and a p-type second reflective layer 20b. The first reflective layer 20a contains a material that is lattice-matched with the material of the substrate 10. The first reflective layer 20a is a semiconductor layer containing n-type Group III-V elements. The second reflective layer 20b is a semiconductor layer containing p-type Group III-V elements. For example, the first reflective layer 20a is a laminate in which multiple n-type GaAs layers and multiple AlGaAs layers are alternately stacked one layer each. The second reflective layer 20b also contains a material that is lattice-matched with the material of the substrate 10. For example, the second reflective layer 20b is a laminate in which multiple p-type GaAs layers and multiple AlGaAs layers are alternately stacked one layer at a time.

[0030] The photodiode layer 120 is provided within the first reflector 20. The photodiode layer 120 is provided between the n-type first reflector 20a and the p-type second reflector 20b. The photodiode layer 120 is a semiconductor layer containing group IV elements and is made of a material that is lattice-matched with the materials of the substrate 10 and the first reflector 20. The photodiode layer 120 absorbs light from the active layer 40 and performs photoelectric conversion. The photodiode layer 120 is, for example, a layer containing Ge (germanium). The photodiode layer 120 may also be a GeSi mixed crystal containing some Si in Ge. In this case, the distortion and light absorption coefficient of the photodiode layer 120 can be controlled by adjusting the Ge and Si content in the material of the photodiode layer 120.

[0031] The first semiconductor layer 30 is located between the first reflector 20 and the second reflector 90 and is a cladding layer provided on the first reflector 20. The first semiconductor layer 30 is a semiconductor layer containing group III-V elements, for example, a semiconductor layer containing n-type GaAs.

[0032] The active layer 40 is provided between the first semiconductor layer 30 and the second semiconductor layer 50. The active layer 40 emits light when power is applied to the first and second semiconductor layers 30 and 50, causing electrons from the first semiconductor layer 30 and holes from the second semiconductor layer 50 to recombine inside the active layer 40. The active layer 40 generates light of a first wavelength. The active layer 40 consists of a multiple quantum well (MQW) layer, such as a laminated film of GaInAs and GaAsP, or a laminated film of (Al)GaInAs and (AlIn)GaAs(P). The elements in parentheses are arbitrary and may or may not be included. The wavelength of the multiple quantum well layer of the AlGaInAs and AlGaInAs laminated film can be arbitrarily controlled by the material composition and film thickness. It is preferable to introduce mutually opposing strains into the multiple quantum well layer and the barrier layer. In this case, for example, the magnitude of the strain can be around 1%, and the number of quantum wells can be 4 to 8.

[0033] The second semiconductor layer 50 is located between the first reflector 20 and the second reflector 90 and is a cladding layer provided on the active layer 40. The second semiconductor layer 50 is a semiconductor layer containing group III-V elements and is a semiconductor layer containing p-type GaAs that is inversely conductive to the first semiconductor layer 30. Therefore, by applying a negative voltage to the first electrode 100 and a positive voltage to the second electrode 110, electrons are supplied from the first semiconductor layer 30 to the active layer 40, and holes are supplied from the second semiconductor layer 50 to the active layer 40.

[0034] The constriction layers 60 and 80 are provided on the second semiconductor layer 50. The constriction layers 60 and 80 are located between the second reflector 90 and the second semiconductor layer 50. Of the constriction layers 60 and 80, the conductive region 60 is provided directly below the light emission region (in the -Z direction) and is composed of a conductive material such as AlAs. The insulating region 80 is provided in a layer at the same height level as the conductive region 60 in the Z direction and is provided around the conductive region 60. The insulating region 80 narrows the planar region of the conductive region 60 in order to concentrate the current flow in the conductive region 60 and constrict the current. The insulating region 80 is formed, for example, by oxidizing the material of the conductive region 60 from both sides (in the X or Y direction). No current flows through the insulating region 80. The insulating region 80 is composed of an insulating material such as AlOx. The insulating region 80 may be a void. In this case, the insulating material such as AlOx in the insulating region 80 is etched away. The constricted layers 60 and 80 allow current to flow through the conductive region 60 without allowing current to flow through the insulating region 80. Furthermore, the constricted layers 60 and 80 concentrate light into the conductive region 60 due to the refractive index difference with the second semiconductor layer 50 or the second reflector 90. Thus, the constricted layers 60 and 80 have the functions of current constriction and light constriction. The conductive region 60 overlaps with the grating GR of the second reflector 90 when viewed from its stacking direction (Z direction). The stacking direction (Z direction) is also the direction in which current flows through the conductive region 60, and the direction in which light resonates between the first reflector 20 and the second reflector 90.

[0035] The second reflector 90 is located above the constricted layers 60 and 80 (in the Z direction). The second reflector 90 is a DBR and is constructed by alternately stacking multiple materials with different refractive indices, one layer at a time. For example, the second reflector 90 has a stacked structure of multiple semiconductor materials (for example, a stacked structure of p-type GaAs and AlGaAs). That is, both the first and second reflectors 20 and 90 are semiconductor DBRs composed of semiconductor materials. In this embodiment, the laser light L generated in the resonator between the first reflector 20 and the second reflector 90 is emitted from the upper surface of the second reflector 90, as indicated by the arrow in Figure 1.

[0036] The surface of the second reflector 90 has a textured layer (grating) GR with an uneven shape. The textured surface of the second reflector 90 is provided on the light emission surface from which the laser light L from the active layer 40 is emitted. For example, when the area of ​​the conductive region 60 or the second reflector 90 as viewed from the Z direction (the area of ​​the aperture OA (Optical Aperture) from which the laser light L is emitted) is relatively large (for example, when the OA diameter is 4 μm or more), the polarization characteristics of the laser light L can be controlled by providing the textured layer GR on the second reflector 90. This makes it possible to increase the output power of the laser light L. However, when the OA diameter is about 4 μm or less, the textured layer GR does not need to be provided. The material of the textured layer GR may also be the uppermost layer of the second reflector 90, or a transparent conductive layer (for example, TiO) provided on the second reflector 90. ２ ) is also acceptable. The pitch of the uneven surface varies depending on the material and wavelength, but for example, it can be about 200 nm to 700 nm. The ratio of the length of the concave part to the length of the convex part of the uneven surface (Duty) can be about 0.3 to 0.7. The height of the convex part of the uneven surface (step difference in the uneven surface) varies depending on the material and wavelength, but generally it can be about 100 nm to 300 nm.

[0037] The first electrode 100 is provided on the first semiconductor layer 30 and is electrically connected to the first semiconductor layer 30. The first electrode 100 is made of a conductive metal such as Ti, Pt, Au, a multilayer film of AuGe and Ni and Au, or a multilayer film of PdGe, Ni and Au. The first electrode 100 is electrically insulated from components other than the first semiconductor layer 30. The first electrode 100 functions as a common cathode for the laser diode and photodiode layer 120, which include the active layer 40.

[0038] The second electrode 110 is provided on the upper surface of the second reflecting mirror 90, and is electrically connected to the second reflecting mirror 90. Further, the second electrode 110 is electrically connected to the second semiconductor layer 50 via the conductive region 60. The second electrode 110 is also made of a conductive metal, for example, Ti, Pt, Au, a laminated film of AuGe, Ni and Au, or a laminated film of PdGe, Ni and Au. The second electrode 110 may be made of the same material as the first electrode 100. The second electrode 110 is provided around the light exit surface of the second reflecting mirror 90. The second electrode 110 functions as an anode of a laser diode including the active layer 40.

[0039] The first and second electrodes 100 and 110 do not overlap with the light exit surface of the second reflecting mirror 90 and the conductive region 60 when viewed from the Z direction. Therefore, the first and second electrodes 100 and 110 do not block the laser light emitted from the second reflecting mirror 90.

[0040] The third electrode 115 is in contact with a part of the first reflective layer 20a, and is electrically connected to the first reflective layer 20a. The third electrode 115 is also made of a conductive metal, for example, Ti, Pt, Au, a laminated film of AuGe, Ni and Au, or a laminated film of PdGe, Ni and Au. The third electrode 115 may be made of the same material as the first and second electrodes 100 and 110. The third electrode 115 functions as an electrode of the photodiode layer 120. Note that the third electrode 115 may be formed on the substrate.

[0041] The insulating film 105 is provided on side surfaces of the first and second reflecting mirrors 20 and 90, the first and second semiconductor layers 30 and 50, the active layer 40, the photodiode layer 120, and the constriction layers 60 and 80. The insulating film 105 suppresses unintended short circuits between these elements and protects these elements. Further, the insulating film 105 electrically insulates the electrodes 100, 110 and 115 from each other.

[0042] According to the present embodiment, the substrate 10 is a GaAs substrate, and the first reflective layer 20a formed thereon includes GaAs. Further, the photodiode layer 120 formed on the first reflective layer 20a is a Ge layer.

[0043] FIG. 2 is a graph showing the relationship between the lattice constant and the band gap of each material. The horizontal axis represents the lattice constant. The vertical axis represents the band gap and the wavelength of absorbed light.

[0044] For example, compared to GaAs, Ge has substantially the same lattice constant. The ratio of the lattice constant of Ge to that of GaAs (strain, degree of lattice mismatch) is about 0.5% or less. In addition, the wavelength of light absorbed by Ge reaches about 2 μm, and Ge can sufficiently absorb long-wavelength light in the SWIR band (about 1 μm to about 1.6 μm) and perform photoelectric conversion thereon. Note that GaAs has an absorption wavelength of less than 1 μm, and cannot sufficiently absorb long-wavelength light in the SWIR band.

[0045] On the other hand, although materials containing In (indium) (InP, InAs, InSb, etc.) have absorption light in the SWIR band, their lattice constants are considerably different from that of GaAs, and the strain (degree of lattice mismatch) relative to GaAs is considerably larger than 0.5%. This also applies to InGaAs containing In. Therefore, when a material containing In (e.g., InGaAs, etc.) is used for the photodiode layer 120, the photodiode layer 120 is strained relative to the substrate 10 and the first reflective layer 20a, resulting in loss of reliability of the device itself.

[0046] FIG. 3 is a graph showing the relationship between the wavelength of absorbed light and the absorption coefficient for Si, InGaAs, and Ge. The horizontal axis represents the wavelength of absorbed light. The vertical axis represents the light absorption coefficient.

[0047] For Si, the absorption coefficient is relatively high for light with a wavelength of 1 μm or less, but the absorption coefficient is relatively low for light with a wavelength longer than 1 μm. In contrast, for InGaAs and Ge, the absorption coefficient is relatively high not only for light with a wavelength of 1 μm or less, but also for light with a wavelength longer than 1 μm. Ge has a favorable absorption coefficient for light with a wavelength up to 1.6 μm.

[0048] For example, SMI-VCSELs have been put into practical use for laser light in the 850 nm band. However, it is expected that the development of SMI-VCSELs will progress to emit laser light with longer wavelengths exceeding 1 μm in the future. Therefore, it is preferable to use InGaAs or Ge as the material for the photodiode layer 120 rather than Si. However, for example, if InGaAs capable of absorbing light with longer wavelengths exceeding 1 μm is formed as the photodiode layer 120 on a GaAs substrate, as described above, a large distortion occurs due to the difference in lattice constants, reducing reliability. In other words, InGaAs that absorbs light with longer wavelengths exceeding 1 μm well cannot be formed on a GaAs substrate while maintaining reliability.

[0049] In contrast, the light-emitting device 1 according to this embodiment uses Ge in the photodiode layer 120, so it is lattice-matched with respect to the substrate 10 and the first reflective layer 20a, and hardly any distortion occurs. Furthermore, Ge can sufficiently absorb long-wavelength light such as the SWIR band that exceeds the 1 μm band. Therefore, the photodiode layer 120 constructed using Ge has few crystal defects, can sufficiently absorb long-wavelength light such as the SWIR band that exceeds the 1 μm band and perform photoelectric conversion, and can improve the reliability of the light-emitting device 1. As a result, the light-emitting device 1 according to this embodiment can emit and absorb long-wavelength light such as the SWIR band that exceeds the 1 μm band (for example, about 1 μm to 1.6 μm) while maintaining reliability. In addition, since the photodiode layer 120 has little distortion, its film thickness can be flexibly changed.

[0050] Furthermore, GaAs and Ge substrates have higher thermal conductivity and superior heat dissipation compared to substrates containing In. Therefore, the light-emitting device 1 according to this embodiment can efficiently dissipate the heat generated internally.

[0051] Next, a method for manufacturing the light-emitting device 1 according to the first embodiment will be described.

[0052] Figures 4 to 9 are cross-sectional views showing an example of a method for manufacturing the light-emitting device 1 according to the first embodiment.

[0053] On the substrate 10 shown in Figure 4, multiple n-type GaAs films and multiple n-type AlGaAs films are alternately epitaxially grown one layer at a time to form a first reflective layer 20a. The substrate 10 is a group III-V substrate, for example, an n-type GaAs substrate or an n-type Ge substrate.

[0054] Next, the material for the photodiode layer 120 is deposited on the first reflective layer 20a. For example, a Group IV element, such as Ge, is epitaxially grown on the first reflective layer 20a as the material for the photodiode layer 120. The lattice constant of Group IV element Ge is approximately the same as that of Group III-V element GaAs. Therefore, the photodiode layer 120 can be epitaxially grown on the substrate 10 in a state of low strain (lattice-matched state). The Group IV element Ge is lattice-matched to the n-type GaAs substrate or n-type Ge substrate of the Group III-V substrate, and a photodiode layer 120 with low strain can be constructed. In addition, a few percent of Al or In may be added to the interface between the first reflective layer 20a and the photodiode layer 120.

[0055] Next, multiple p-type GaAs films and multiple p-type AlGaAs films are epitaxially grown alternately, one layer at a time, on the photodiode layer 120 to form the second reflective layer 20b.

[0056] Next, the materials for the first semiconductor layer 30, the active layer 40, the second semiconductor layer 50, and the conductive region 60 are epitaxially grown in this order. The material for the first semiconductor layer 30 is, for example, n-type GaAs. The material for the active layer 40 is, for example, a stack of AlGaInAs / AlGaInAs, or a stack of GaInAsP / GaInAsP. The material for the second semiconductor layer 50 is, for example, p-type GaAs. The material for the conductive region 60 is, for example, AlAs.

[0057] Next, multiple p-type GaAs films and multiple p-type AlGaAs films are epitaxially grown one layer at a time alternately on the conductive region 60 to form the second reflecting mirror 90. This results in the structure shown in Figure 4.

[0058] Next, using lithography and etching techniques, a textured layer GR is formed on the laser light emission region of the surface of the second reflector 90, as shown in Figure 5. The textured layer GR may also be the uppermost layer of the second reflector 90, and may be a transparent conductive layer (for example, TiO) provided on the second reflector 90. ２ ) is also acceptable. The pitch of the uneven surface varies depending on the material and wavelength, but for example, it can be about 200 nm to 700 nm. The ratio (Duty) of the length of the concave part to the length of the convex part of the uneven surface is about 0.3 to 0.7. The height of the convex part of the uneven surface (step difference in the uneven surface) varies depending on the material and wavelength, but is generally about 100 nm to 300 nm. By providing an uneven layer on the second reflector 90, the polarization characteristics of the laser light can be controlled. This makes it possible to increase the output power of the laser light.

[0059] Next, using lithography and etching techniques, the second reflector 90, the conductive region 60, the second semiconductor layer 50, and the active layer 40 are processed into a first mesa structure as shown in Figure 6. At this time, the upper surface of the first semiconductor layer 30, on which the first electrode 100 is to be formed, is exposed.

[0060] Next, as shown in Figure 7, the conductive region 60 is oxidized from both sides. As a result, the conductive region 60 remains directly below the grating GR (in the -Z direction), and an insulating region 80 containing aluminum oxide (AlOx) is formed around the conductive region 60 in a second mesa structure that is wider than the first mesa structure. At this time, the conductive region 60 can have the functions of current constriction and light constriction.

[0061] Next, using lithography and etching techniques, the first semiconductor layer 30, the second reflective layer 20b, the photodiode layer 120, and the upper part of the first reflective layer 20a are processed as shown in Figure 8. At this time, the upper surface of the lower layer of the first reflective layer 20a, where the third electrode 115 is to be formed, is exposed.

[0062] Next, the insulating film 105 material (e.g., silicon oxide) is deposited on the structure shown in Figure 8. Then, using lithography and etching techniques, the insulating film 105 material in the formation areas of the grating GR and the first to third electrodes 100, 110, and 115 is removed, as shown in Figure 9.

[0063] Next, conductive materials (e.g., AuGe, Ti, Pt, Ni, or Au) for the first to third electrodes 100, 110, and 115 are deposited on the structure shown in Figure 9.

[0064] Next, the conductive materials for the first to third electrodes 100, 110, and 115 are processed using lithography and etching techniques. As a result, as shown in Figure 1, the first electrode 100 is formed on the first semiconductor layer 30, the second electrode 110 is formed around the grating GR of the second reflector 90, and the third electrode 115 is formed on the intermediate layer of the first reflector layer 20a. This completes the light-emitting device 1 according to the first embodiment.

[0065] In this embodiment, the light-emitting device 1 uses Ge in the photodiode layer 120, so it is lattice-matched with respect to the substrate 10 and the first reflective layer 20a, and hardly any distortion occurs. Furthermore, Ge can sufficiently absorb long-wavelength light such as the SWIR band, which exceeds the 1 μm band. As a result, the light-emitting device 1 in this embodiment can emit and absorb long-wavelength light such as the SWIR band while maintaining reliability.

[0066] (Second Embodiment) Figure 10 is a cross-sectional view showing an example of the configuration of the light-emitting device 1 according to the second embodiment. The second embodiment is an example in which the first embodiment is applied to a back-illuminated SMI-VCSEL. In this case, the second electrode 110 and the insulating film 105 cover the +Z side surface of the second reflector 90, and the laser light L does not emit from the second reflector 90. The laser light L is emitted from the substrate 10 side as shown by the arrow in Figure 10. In this case, an undoped low-carrier concentration substrate (semi-insulating (SI) substrate) may be used for the substrate 10.

[0067] The other components of the second embodiment may be the same as those of the first embodiment. Therefore, the second embodiment can obtain the same effects as the first embodiment.

[0068] (Third Embodiment) Figure 11 is a cross-sectional view showing an example of the configuration of the light-emitting device 1 according to the third embodiment. In the third embodiment, the current to the active layer 40 is narrowed using a buried tunnel junction (BTJ) with a high impurity concentration. The BTJ is constructed by stacking third and fourth semiconductor layers 61 and 71. Hereinafter, the third and fourth semiconductor layers 61 and 71 will also be referred to as BTJ 61 and 71.

[0069] The third semiconductor layer 61 is provided on the second semiconductor layer 50. The third semiconductor layer 61 is located between the second reflector 90 and the second semiconductor layer 50. The third semiconductor layer 61 is made of a p-type semiconductor, for example, p-type (Al)GaAs. The p-type impurity concentration of the third semiconductor layer 61 is higher than that of the second semiconductor layer 50.

[0070] The fourth semiconductor layer 71 is provided on the third semiconductor layer 61. The fourth semiconductor layer 71 is also located between the second reflector 90 and the second semiconductor layer 50. The fourth semiconductor layer 71 is made of an n-type semiconductor, for example, n-type (Al)GaAs. The n-type impurity concentration of the fourth semiconductor layer 71 is higher than that of the fifth semiconductor layer 81.

[0071] When viewed from the stacking direction (Z direction), BTJs 61 and 71 overlap with the grating GR of the second reflector 90. The stacking direction (Z direction) is also the direction in which current flows through BTJs 61 and 71, and the direction in which light resonates between the first reflector 20 and the second reflector 90.

[0072] The fifth semiconductor layer 81 is provided on the second semiconductor layer 50 and the BTJs 61 and 71. The fifth semiconductor layer 81 covers the BTJs 61 and 71. The fifth semiconductor layer 81 is made of an n-type semiconductor, for example, n-type GaAs. The n-type impurity concentration of the fifth semiconductor layer 81 is lower than that of the fourth semiconductor layer 71. Therefore, current does not easily flow at the junction between the fifth semiconductor layer 81 and the second semiconductor layer 50.

[0073] The current between electrodes 100 and 110 flows concentrated and narrowed in BTJs 61 and 71. This allows BTJs 61 and 71 to promote light emission in the active layer 40 directly beneath them. Furthermore, the top and side surfaces of BTJs 61 and 71 are covered with a fifth semiconductor layer 81. At the contact surface between the side surfaces of BTJs 61 and 71 and the fifth semiconductor layer 81, the difference in refractive index between these materials causes light to be narrowed in BTJs 61 and 71. In other words, BTJs 61 and 71 have the functions of current narrowing and light narrowing.

[0074] The other configurations of the third embodiment may be the same as those of the first embodiment. Therefore, the third embodiment can obtain the same effects as the first embodiment.

[0075] (Fourth Embodiment) Figure 12 is a cross-sectional view showing an example of the configuration of the light-emitting device 1 according to the fourth embodiment. The fourth embodiment is an example in which the third embodiment is applied to a back-illuminated SMI-VCSEL. In this case, the second electrode 110 and the insulating film 105 cover the +Z side surface of the second reflector 90, and the laser light L does not emit from the second reflector 90. The laser light L is emitted from the substrate 10 side as shown by the arrow in Figure 12. In this case, an undoped low-carrier concentration substrate (semi-insulating substrate) may be used for the substrate 10.

[0076] The other components of the fourth embodiment may be the same as those of the third embodiment. Therefore, the fourth embodiment can obtain the same effects as the third embodiment.

[0077] (Fifth Embodiment) Figure 13 is a cross-sectional view showing an example of the configuration of the light-emitting device 1 according to the fifth embodiment. In the fifth embodiment, the current to the active layer 40 is narrowed using a tunnel junction (TJ) and implant region 85 with a high impurity concentration. The TJ is constructed by stacking third and fourth semiconductor layers 61 and 71. The third and fourth semiconductor layers 61 and 71 constitute a tunnel junction, but are not embedded in the semiconductor layer or the like. Therefore, hereafter, the third and fourth semiconductor layers 61 and 71 will also be referred to as TJ 61 and 71.

[0078] The fifth embodiment includes TJs 61 and 71 provided between the second reflector 90 and the second semiconductor layer 50, and an implant region 85 provided around the TJs 61 and 71.

[0079] The third and fourth semiconductor layers 61 and 71 have the same configuration as those in the third embodiment, but are not embedded in the fifth semiconductor layer 81. However, an implant region 85 is provided around the TJs 61 and 71.

[0080] The implant region 85 is formed by implanting impurities such as H, He, O, and B in the lower part of the second reflector 90 and in the upper parts of the third and fourth semiconductor layers 61 and 71 and the second semiconductor layer 50, in areas that do not allow current or light to pass through. The implant region 85 is in a non-conductive or high-resistance state due to the introduction of crystal defects by the implantation of impurities.

[0081] According to the fifth embodiment, the current is constricted by the implant region 85. The current between electrodes 100 and 110 flows to and is constricted in TJs 61 and 71. As a result, TJs 61 and 71 can promote luminescence in the active layer 40 directly beneath them.

[0082] The other components of the fifth embodiment may be the same as those of the first embodiment. Therefore, the fifth embodiment can obtain the same effects as the first embodiment.

[0083] (Sixth Embodiment) Figure 14 is a cross-sectional view showing an example of the configuration of the light-emitting device 1 according to the sixth embodiment. The sixth embodiment is an example in which the fifth embodiment is applied to a back-illuminated SMI-VCSEL. In this case, the second electrode 110 and the insulating film 105 cover the +Z side surface of the second reflector 90, and the laser light L does not emit from the second reflector 90. The laser light L is emitted from the substrate 10 side as shown by the arrow in Figure 14. In this case, an undoped low-carrier concentration substrate (semi-insulating substrate) may be used for the substrate 10.

[0084] The other components of the sixth embodiment may be the same as those of the fifth embodiment. Therefore, the sixth embodiment can obtain the same effects as the fifth embodiment.

[0085] (Seventh Embodiment) Figure 15 is a cross-sectional view showing an example of the configuration of the light-emitting device 1 according to the seventh embodiment. In the seventh embodiment, InP-based materials are used for the first semiconductor layer 30, the active layer 40, the second semiconductor layer 50, the BTJs 61 and 71, and the fifth semiconductor layer 81. The substrate 10 and the first reflector 20 are made of GaAs-based materials, as in the first embodiment. The light-emitting device 1 of the seventh embodiment is constructed by bonding an InP-based structure to a GaAs-based structure.

[0086] For example, the substrate 10 and the first reflector 20 are formed in the same manner as in the first embodiment. Separately from the substrate 10 and the first reflector 20, a first semiconductor layer 30, an active layer 40, a second semiconductor layer 50, BTJs 61 and 71, a fifth semiconductor layer 81, and a second reflector 90 are formed on the InP substrate. Then, the structure formed on the InP substrate is bonded onto the substrate 10 and the first reflector 20. In this case, the bonding surface is located at Fb in Figure 15.

[0087] For example, n-type InP is used for the first semiconductor layer 30. The material of the active layer 40 may be the same as in the first embodiment. For example, p-type InP is used for the second semiconductor layer 50, and for example, p-type AlGaInAs is used for the third semiconductor layer 61. For example, n-type InP or n-type AlGaInAs is used for the fourth semiconductor layer 71. For example, n-type InP is used for the fifth semiconductor layer 81. For example, n-type InP is used for the second reflector 90. ２ and TiO ２ It has a laminated structure. In this case, the first reflector 20 is a semiconductor DBR made of a semiconductor material, and the second reflector 90 is a dielectric DBR made of a dielectric material.

[0088] Furthermore, according to the seventh embodiment, since a DBR layer having a laminated structure of GaAs and AlGaAs that can achieve a large refractive index difference can be used in the first reflector 20, a reflector with high reflectivity and a wide stopband can be used in the first reflector 20.

[0089] The other configurations of the seventh embodiment may be the same as those of the first embodiment. Therefore, the seventh embodiment can obtain the same effects as the first embodiment. Furthermore, according to the seventh embodiment, since the substrate 10 side uses a GaAs-based material, superior heat dissipation is ensured.

[0090] (Eighth Embodiment) Figure 16 is a cross-sectional view showing an example of the configuration of the light-emitting device 1 according to the eighth embodiment. The eighth embodiment is an example in which the seventh embodiment is applied to a back-illuminated SMI-VCSEL. In this case, the second electrode 110 and the insulating film 105 cover the +Z side surface of the second reflector 90, and the laser light L does not emit from the second reflector 90. The laser light L is emitted from the substrate 10 side as shown by the arrow in Figure 16. In this case, an undoped low-carrier concentration substrate (semi-insulating substrate) may be used for the substrate 10.

[0091] The other configurations of the eighth embodiment may be the same as those of the seventh embodiment. Therefore, the eighth embodiment can obtain the same effects as the seventh embodiment.

[0092] (Ninth Embodiment) Figure 17 is a cross-sectional view showing an example of the configuration of the light-emitting device 1 according to the ninth embodiment. In the ninth embodiment, the photodiode layer 120 is made up of an avalanche photodiode.

[0093] The photodiode layer 120 is provided between the first reflective layer 20a and the second reflective layer 20b. The photodiode layer 120 is constructed by stacking a photoelectric conversion layer 121, a transition layer 122, and an avalanche multiplication layer 123.

[0094] The photoelectric conversion layer 121 is provided between the first reflective layer 20a and the transition layer 122. It generates electric charge by photoelectrically converting light of the first wavelength generated in the active layer 40. The photoelectric conversion layer 121 is made of a material that is lattice-matched to the first reflective layer 20a, such as intrinsic Ge without impurities.

[0095] The transition layer 122 is provided between the photoelectric conversion layer 121 and the avalanche multiplication layer 123. The transition layer 122 transfers the charge (e.g., holes) generated in the photoelectric conversion layer 121 to the avalanche multiplication layer 123. The transition layer 122 is composed of, for example, intrinsic InGaAs without introduced impurities. The transition layer 122 may be a single layer structure. However, it is preferable to have a layered structure (e.g., a three-layer structure) in which the composition of the transition layer 122 is changed in steps to create a stepped band gap. This lowers the band barrier and makes it easier for charge to move.

[0096] The avalanche multiplication layer 123 is provided between the transition layer 122 and the second reflective layer 20b. The avalanche multiplication layer 123 avalanches the charge generated in the photoelectric conversion layer 121 and transitioned across the transition layer 122. The avalanche-multiplied current is measured externally as a photocurrent. The avalanche multiplication layer 123 is composed of a laminated film of an n-type multiplication semiconductor layer 123n and a p-type multiplication semiconductor layer 123p. The n-type multiplication semiconductor layer 123n and the p-type multiplication semiconductor layer 123p constitute a pn junction. A reference voltage (e.g., ground voltage) is applied to the first electrode 100 as a common cathode. A positive voltage is applied to the third electrode 115 as an anode. As a result, a reverse bias is applied to the pn junction of the n-type multiplication semiconductor layer 123n and the p-type multiplication semiconductor layer 123p. A depletion layer is formed at the pn junction where a reverse bias is applied. When charge enters this depletion layer, avalanche multiplication occurs and a photocurrent flows. As a result, even when the current from the photoelectric conversion layer 121 is small, the avalanche multiplication layer 123 can increase the current to a large amount through avalanche multiplication. The n-type multiplication semiconductor layer 123n is composed of, for example, n-type GaAs or n-type AlGaAs. The p-type multiplication semiconductor layer 123p is composed of, for example, p-type GaAs or p-type AlGaAs.

[0097] The photoelectric conversion layer 121, the transition layer 122, and the avalanche multiplication layer 123 are stacked in this order in the Z direction from the first reflective layer 20a to the second reflective layer 20b. As a result, the charge (holes) generated in the photoelectric conversion layer 121 can drift from the third electrode 115 (anode) side to the first electrode 100 (cathode) side and enter the avalanche multiplication layer 123.

[0098] Furthermore, the n-type multiplier semiconductor layer 123n and the p-type multiplier semiconductor layer 123p of the avalanche multiplier layer 123 are stacked in this order in the Z direction. As a result, the pn junction of the n-type multiplier semiconductor layer 123n and the p-type multiplier semiconductor layer 123p can be reverse-biased between the first electrode 100 (cathode) and the third electrode 115 (anode). Consequently, the photodiode layer 120 can multiply the charge photoelectrically converted in the photoelectric conversion layer 121 by avalanche multiplier in the avalanche multiplier layer 123 to a relatively large current. This increases the degree of freedom in the film thickness and position of the photodiode layer 120. That is, the film thickness of the photodiode layer 120 can be made thinner, or the photodiode layer 120 can be separated from the active layer 40. Therefore, a decrease in the output of the laser light can be suppressed.

[0099] According to the ninth embodiment, since the photoelectric conversion layer 121 is lattice-matched with the first reflective layer 20a, an In-based material that causes strain in the transition layer 122 even with SWIR band light may be used.

[0100] The other configurations of the ninth embodiment may be the same as those of the first embodiment. Therefore, the ninth embodiment can obtain the same effects as the first embodiment. The ninth embodiment may be combined with any of the second to eighth embodiments. In this way, the ninth embodiment can obtain the effects of any of the second to eighth embodiments.

[0101] The above embodiment is merely one example of the configuration of SMI-VCSEL, and other configurations are also possible.

[0102] (Examples of application to mobile devices) The technology disclosed herein (the technology) can be applied to various products. For example, the technology disclosed herein may be implemented as a device mounted on any type of mobile device such as automobiles, electric vehicles, hybrid electric vehicles, motorcycles, bicycles, personal mobility devices, airplanes, drones, ships, and robots.

[0103] Figure 18 is a block diagram showing a schematic configuration example of a vehicle control system, which is an example of a mobile control system to which the technology described herein may be applied.

[0104] The vehicle control system 12000 comprises a plurality of electronic control units connected via a communication network 12001. In the example shown in Figure 18, the vehicle control system 12000 includes a drive system control unit 12010, a body system control unit 12020, an external information detection unit 12030, an internal information detection unit 12040, and an integrated control unit 12050. The functional configuration of the integrated control unit 12050 is shown in the figure, which includes a microcomputer 12051, an audio / image output unit 12052, and an in-vehicle network interface 12053.

[0105] The drivetrain control unit 12010 controls the operation of devices related to the vehicle's drivetrain according to various programs. For example, the drivetrain control unit 12010 functions as a control device for a drivetrain generating device that generates driving force for the vehicle, such as an internal combustion engine or a drive motor; a drivetrain transmission mechanism that transmits driving force to the wheels; a steering mechanism that adjusts the steering angle of the vehicle; and a braking device that generates braking force for the vehicle.

[0106] The body system control unit 12020 controls the operation of various devices mounted on the vehicle body according to various programs. For example, the body system control unit 12020 functions as a control device for a keyless entry system, a smart key system, a power window system, or various lamps such as headlights, reverse lights, brake lights, turn signals, or fog lights. In this case, the body system control unit 12020 may receive radio waves transmitted from a portable device that replaces a key or signals from various switches. The body system control unit 12020 receives these radio waves or signals and controls the vehicle's door lock system, power window system, lamps, etc.

[0107] The external information detection unit 12030 detects information from outside the vehicle equipped with the vehicle control system 12000. For example, an imaging unit 12031 is connected to the external information detection unit 12030. The external information detection unit 12030 causes the imaging unit 12031 to capture images of the outside of the vehicle and receives the captured images. Based on the received images, the external information detection unit 12030 may perform object detection processing such as detecting people, cars, obstacles, signs, or characters on the road surface, or distance detection processing.

[0108] The imaging unit 12031 is a light 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.

[0109] The in-vehicle information detection unit 12040 detects information inside the vehicle. The in-vehicle information detection unit 12040 is connected to, for example, a driver status detection unit 12041 that detects the driver's state. The driver status detection unit 12041 includes, for example, a camera that captures images of the driver, and the in-vehicle information detection unit 12040 may calculate the driver's level of fatigue or concentration, or determine whether the driver is drowsy, based on the detection information input from the driver status detection unit 12041.

[0110] The microcomputer 12051 can calculate control target values ​​for the drive force generator, steering mechanism, or braking device based on information inside and outside the vehicle acquired by the external information detection unit 12030 or the internal information detection unit 12040, and output control commands to the drive system control unit 12010. For example, the microcomputer 12051 can perform cooperative control aimed at realizing ADAS (Advanced Driver Assistance System) functions, including collision avoidance or impact mitigation, following driving based on distance between vehicles, maintaining vehicle speed, vehicle collision warning, or vehicle lane departure warning.

[0111] Furthermore, the microcomputer 12051 can perform cooperative control for purposes such as autonomous driving, where the vehicle drives autonomously without driver intervention, by controlling the drive force generating device, steering mechanism, or braking device, etc., based on information about the vehicle's surroundings acquired by the external information detection unit 12030 or the internal information detection unit 12040.

[0112] Furthermore, the microcomputer 12051 can output control commands to the body system control unit 12020 based on external information acquired by the external information detection unit 12030. For example, the microcomputer 12051 can control the headlights according to the position of a preceding or oncoming vehicle detected by the external information detection unit 12030, and perform coordinated control aimed at reducing glare, such as switching from high beams to low beams.

[0113] The audio-image output unit 12052 transmits at least one of audio and image output signals to an output device capable of visually or audibly notifying information to the vehicle's occupants or to those outside the vehicle. In the example shown in Figure 18, the output devices include an audio speaker 12061, a display unit 12062, and an instrument panel 12063. The display unit 12062 may include, for example, at least one of an onboard display and a head-up display.

[0114] Figure 19 shows an example of the installation position of the imaging unit 12031.

[0115] In Figure 19, the imaging unit 12031 includes imaging units 12101, 12102, 12103, 12104, and 12105.

[0116] The imaging units 12101, 12102, 12103, 12104, and 12105 are installed, for example, on the front nose, side mirrors, rear bumper, back door, and the upper part of the windshield inside the vehicle 12100. The imaging unit 12101 installed on the front nose and the imaging unit 12105 installed on the upper part of the windshield inside the vehicle mainly acquire images of the front of the vehicle 12100. The imaging units 12102 and 12103 installed on the side mirrors mainly acquire images of the sides of the vehicle 12100. The imaging unit 12104 installed on the rear bumper or back door mainly acquires images of the rear of the vehicle 12100. The imaging unit 12105 installed on the upper part of the windshield inside the vehicle is mainly used for detecting preceding vehicles, pedestrians, obstacles, traffic lights, traffic signs, or lanes.

[0117] Figure 19 shows an example of the imaging range of imaging units 12101 to 12104. Imaging range 12111 indicates the imaging range of imaging unit 12101 located on the front nose, imaging ranges 12112 and 12113 indicate the imaging ranges of imaging units 12102 and 12103 located on the side mirrors, respectively, and imaging range 12114 indicates the imaging range of imaging unit 12104 located on the rear bumper or back door. For example, by superimposing the image data captured by imaging units 12101 to 12104, an overhead view image of the vehicle 12100 can be obtained.

[0118] At least one of the imaging units 12101 to 12104 may have a function for acquiring distance information. For example, at least one of the imaging units 12101 to 12104 may be a stereo camera consisting of multiple image sensors, or an image sensor having pixels for phase difference detection.

[0119] For example, the microcomputer 12051, based on distance information obtained from the imaging units 12101 to 12104, can determine the distance to each object within the imaging range 12111 to 12114 and the temporal change of this distance (relative speed to the vehicle 12100). In particular, it can extract the closest object on the vehicle 12100's path that is traveling in approximately the same direction as the vehicle 12100 at a predetermined speed (e.g., 0 km / h or more) as the preceding vehicle. Furthermore, the microcomputer 12051 can set a predetermined distance to be maintained before the preceding vehicle and perform automatic braking control (including follow-and-stop control) and automatic acceleration control (including follow-and-start control), etc. In this way, cooperative control aimed at autonomous driving, where the vehicle drives autonomously without driver intervention, can be performed.

[0120] For example, the microcomputer 12051 can use distance information obtained from imaging units 12101 to 12104 to classify and extract three-dimensional object data related to three-dimensional objects, such as motorcycles, passenger cars, large vehicles, pedestrians, utility poles, and other three-dimensional objects, and use this data for automatic obstacle avoidance. For example, the microcomputer 12051 identifies 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. If the collision risk is above a set value and there is a possibility of collision, the microcomputer 12051 can provide driving assistance to avoid collisions by outputting a warning to the driver via the audio speaker 12061 or the display unit 12062, or by performing forced deceleration or evasive steering via the drive system control unit 12010.

[0121] At least one of the imaging units 12101 to 12104 may be an infrared camera that detects infrared light. For example, the microcomputer 12051 can recognize pedestrians by determining whether or not pedestrians are present in the images captured by the imaging units 12101 to 12104. Such pedestrian recognition is performed, for example, by a procedure to extract feature points from the images captured by the imaging units 12101 to 12104 as infrared cameras, and a procedure to perform pattern matching on a series of feature points that indicate the contour of an object to determine whether or not it is a pedestrian. When the microcomputer 12051 determines that a pedestrian is present in the images captured by the imaging units 12101 to 12104 and recognizes a pedestrian, the audio-image output unit 12052 controls the display unit 12062 to superimpose a rectangular contour line for emphasis on the recognized pedestrian. The audio-image output unit 12052 may also control the display unit 12062 to display an icon indicating a pedestrian at a desired position.

[0122] The above describes an example of a vehicle control system to which the technology described herein may be applied. The technology described herein may be applied to, for example, the imaging unit 12031, among the configurations described above.

[0123] Furthermore, this technology can be configured as follows:

[0124] (1) A light-emitting device comprising: a substrate containing a group III-V element or a group IV element; a first reflector provided on the substrate; a second reflector provided above the first reflector; a first semiconductor layer of a first conductivity type and a second semiconductor layer of a second conductivity type provided between the first reflector and the second reflector; an active layer provided between the first semiconductor layer and the second semiconductor layer, which generates light of a first wavelength by applying power to the first and second semiconductor layers; and a photodiode layer provided within the first reflector, which contains a group IV element and generates an electric charge by photoelectric conversion of the light of the first wavelength.

[0125] (2) The light-emitting device according to (1), wherein the first reflective portion includes a first reflective layer containing a first conductivity type III-V element layer and a second reflective layer containing a second conductivity type III-V element layer, and the photodiode layer is provided between the first reflective layer and the second reflective layer.

[0126] (3) The light-emitting apparatus according to (1) or (2), wherein the substrate is a substrate containing GaAs (gallium arsenide) or a substrate containing Ge (germanium).

[0127] (4) The light-emitting device according to any one of (1) to (3), wherein the photodiode layer is a layer containing Ge.

[0128] (5) The light-emitting device according to any one of (1) to (4), wherein the first and second semiconductor layers are semiconductor layers containing group III-V elements, and the second reflector is a laminate of a plurality of semiconductor layers containing group III-V elements.

[0129] (6) The light-emitting apparatus according to (5), wherein the first and second semiconductor layers are semiconductor layers containing GaAs, and the second reflective portion is a laminate of a plurality of GaAs layers and a plurality of AlGaAs layers.

[0130] (7) The light-emitting apparatus according to any one of (1) to (4), wherein the first and second semiconductor layers are semiconductor layers containing InP.

[0131] (8) The light-emitting device according to (7), wherein the second reflecting portion is a laminate of a plurality of dielectric layers.

[0132] (9) The light-emitting apparatus according to (7) or (8), wherein the substrate, the first reflector and the photodiode layer include GaAs or Ge, and there is a bonding surface between the first reflector and the first semiconductor layer.

[0133] (10) The light-emitting device according to (2), further comprising: a first electrode electrically connected to the first semiconductor layer; a second electrode electrically connected to the second semiconductor layer; and a third electrode electrically connected to the first reflective layer.

[0134] (11) The light-emitting device according to any one of (1) to (10), wherein the second reflecting portion comprises an uneven layer having an uneven shape on the light-emitting surface from which light from the active layer is emitted.

[0135] (12) The light-emitting device according to any one of (1) to (11), further comprising a constricted layer including a conductive region provided between the second reflective portion and the second semiconductor layer and an insulating region provided around the conductive region.

[0136] (13) The light-emitting device according to any one of (1) to (11), further comprising: a third semiconductor layer provided on the second semiconductor layer between the second reflecting portion and the second semiconductor layer, having a higher concentration of impurities of the second conductivity type than the second semiconductor layer; and a fourth semiconductor layer of the first conductivity type provided on the third semiconductor layer, forming a tunnel junction with the third semiconductor layer.

[0137] (14) The light-emitting device according to (13), further comprising a fifth semiconductor layer provided on the fourth semiconductor layer, wherein the fifth semiconductor layer includes a conductive region sandwiched between the first reflector and the second reflector and an impurity implant region provided around the conductive region.

[0138] (15) The light-emitting device according to any one of (1) to (14), wherein the light from the active layer is emitted from the substrate side.

[0139] (16) The light-emitting device according to any one of (1) to (15), wherein the photodiode layer is an avalanche photodiode.

[0140] (17) The light-emitting device according to (16), wherein the photodiode layer includes a photoelectric conversion layer that converts light of the first wavelength into electricity to generate an electric charge, and a multiplier layer that multiplies the electric charge by avalanche.

[0141] (18) The light-emitting device according to (17), wherein the photodiode layer further includes a transition layer provided between the photoelectric conversion layer and the multiplier layer, which transfers the charge generated in the photoelectric conversion layer to the multiplier layer.

[0142] Furthermore, this disclosure is not limited to the embodiments described above, and various modifications are possible without departing from the gist of this disclosure. Also, the effects described herein are merely illustrative and not limiting, and other effects may exist.

[0143] 1. Light-emitting device 10. Substrate 20. First reflector 30. First semiconductor layer 40. Active layer 50. Second semiconductor layer 60, 80. Constriction layer 90. Second reflector 100. First electrode 105. Insulating film 110. Second electrode 115. Third electrode 120. Photodiode layer

Claims

1. A light-emitting device comprising: a substrate containing a group III-V element or a group IV element; a first reflecting portion provided on the substrate; a second reflecting portion provided above the first reflecting portion; a first semiconductor layer of a first conductivity type and a second semiconductor layer of a second conductivity type provided between the first reflecting portion and the second reflecting portion; an active layer provided between the first semiconductor layer and the second semiconductor layer, which generates light of a first wavelength by applying power to the first and second semiconductor layers; and a photodiode layer provided within the first reflecting portion, which contains a group IV element and generates an electric charge by photoelectric conversion of the light of the first wavelength.

2. The light-emitting device according to claim 1, wherein the first reflective portion includes a first reflective layer containing a first conductivity type III-V element layer and a second reflective layer containing a second conductivity type III-V element layer, and the photodiode layer is provided between the first reflective layer and the second reflective layer.

3. The light-emitting device according to claim 1, wherein the substrate is a substrate containing GaAs (gallium arsenide) or a substrate containing Ge (germanium).

4. The light-emitting device according to claim 1, wherein the photodiode layer is a layer containing Ge.

5. The light-emitting device according to claim 1, wherein the first and second semiconductor layers are semiconductor layers containing group III-V elements, and the second reflective portion is a laminate of a plurality of semiconductor layers containing group III-V elements.

6. The light-emitting apparatus according to claim 5, wherein the first and second semiconductor layers are semiconductor layers containing GaAs, and the second reflective portion is a laminate of a plurality of GaAs layers and a plurality of AlGaAs layers.

7. The light-emitting apparatus according to claim 1, wherein the first and second semiconductor layers are semiconductor layers containing InP.

8. The light-emitting device according to claim 7, wherein the second reflective portion is a laminate of a plurality of dielectric layers.

9. The light-emitting apparatus according to claim 7, wherein the substrate, the first reflector, and the photodiode layer contain GaAs or Ge, and there is a bonding surface between the first reflector and the first semiconductor layer.

10. The light-emitting device according to claim 2, further comprising: a first electrode electrically connected to the first semiconductor layer; a second electrode electrically connected to the second semiconductor layer; and a third electrode electrically connected to the first reflective layer.

11. The light-emitting device according to claim 1, wherein the second reflective portion comprises an uneven layer having an uneven shape on the light-emitting surface from which light from the active layer is emitted.

12. The light-emitting device according to claim 1, further comprising a constricted layer including a conductive region provided between the second reflective portion and the second semiconductor layer, and an insulating region provided around the conductive region.

13. The light-emitting device according to claim 1, further comprising: a third semiconductor layer provided on the second semiconductor layer between the second reflective portion and the second semiconductor layer, having a higher concentration of impurities of the second conductivity type than the second semiconductor layer; and a fourth semiconductor layer of the first conductivity type provided on the third semiconductor layer, forming a tunnel junction with the third semiconductor layer.

14. The light-emitting device according to claim 13, further comprising a fifth semiconductor layer provided on the fourth semiconductor layer, wherein the fifth semiconductor layer includes a conductive region sandwiched between the first reflector and the second reflector, and an impurity implant region provided around the conductive region.

15. The light-emitting device according to claim 1, wherein the light from the active layer is emitted from the substrate side.

16. The light-emitting device according to claim 1, wherein the photodiode layer is an avalanche photodiode.

17. The light-emitting device according to claim 16, wherein the photodiode layer includes a photoelectric conversion layer that converts light of the first wavelength into electricity to generate an electric charge, and a multiplier layer that multiplies the electric charge by avalanche.

18. The light-emitting device according to claim 17, wherein the photodiode layer further includes a transition layer provided between the photoelectric conversion layer and the multiplier layer, which transfers the charge generated in the photoelectric conversion layer to the multiplier layer.

Images