Light-emitting device

Abstract

[Problem] To provide a light-emitting device with which it is possible to stably generate high output from a light-emitting element. [Solution] A light-emitting device according to the present disclosure comprises: a substrate; a first DBR that is provided on the substrate; an active layer that is provided on the first DBR; a second DBR that is provided on the active layer; and a first semiconductor layer that is provided between the active layer and the second DBR and has a resistivity lower than the resistivity of the second DBR, or that is provided between the active layer and the first DBR and has a resistivity lower than the resistivity of the first DBR.

Description

Light-emitting device

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

[0002] As a type of semiconductor laser, surface-emitting lasers such as VCSELs (Vertical Cavity Surface Emitting Lasers) are known. Generally, in light-emitting devices that utilize surface-emitting lasers, multiple light-emitting elements are formed in a two-dimensional array on the surface or back surface of a substrate.

[0003] Japanese Patent Publication No. 2009-141119, International Patent Application Publication No. WO2022 / 209375, Japanese Patent Publication No. 2019-121757

[0004] There is a growing need for VCSELs capable of high peak power operation for LiDAR (Light Detection and Ranging) applications. For example, there has been a rapid increase in reports and new product announcements regarding a type of VCSEL called multi-junction VCSEL (MJ-VCSEL) in recent years. This is a VCSEL in which multiple active layers are stacked in series using multiple tunnel junction (TJ) layers, and is suitable for short-pulse, high-peak driving such as LiDAR driving, with the output efficiency (Slope Efficiency: SE) to the injected current improving as the number of stacks increases. However, MJ-VCSELs have a problem in that the oscillation transverse modes tend to be non-monophasic compared to conventional VCSELs without TJ layers. For example, it has been reported that donut-shaped near-field images can be observed even with MJ-VCSELs with an OA (Optical Aperture) diameter of less than 30 μm, which are commonly used.

[0005] On the other hand, to realize a high-power VCSEL array, it is effective to increase the VCSEL filling factor (FF) across the entire chip. The FF can be increased by increasing the OA diameter. However, when the OA diameter increases, the number of possible transverse modes in the VCSEL increases, making non-unimodal oscillations, as mentioned above, more likely to occur. In this case, depending on the driving conditions, the characteristics of the VCSEL, such as near-field and far-field images, may no longer meet the requirements for a light source for LiDAR.

[0006] Based on the above explanation, in order to realize a high peak power VCSEL array for LiDAR, it is effective to form an MJ-VCSEL with a large stack count, high SE, and large OA diameter. However, in this case, it may become impossible to obtain the near-field and far-field images desirable for a LiDAR light source. Within the scope of generally recognized design theories, it is difficult to realize an MJ-VCSEL with a large OA radius and good characteristics.

[0007] Therefore, this disclosure provides a light-emitting device capable of stably generating high output from a light-emitting element.

[0008] The light-emitting device of the first aspect of this disclosure comprises a substrate, a first DBR provided on the substrate, an active layer provided on the first DBR, a second DBR provided on the active layer, and a first semiconductor layer provided between the active layer and the second DBR and having a resistivity lower than the resistivity of the second DBR, or provided between the active layer and the first DBR and having a resistivity lower than the resistivity of the first DBR. This makes it possible to stably generate high power from the light-emitting element. For example, it becomes possible to make the distribution of current flowing in the second DBR or the first DBR and in the first semiconductor layer closer to a uniform distribution in the first semiconductor layer, and it becomes possible to improve the light emission profile of the light emitted from the light-emitting element.

[0009] Furthermore, in this first aspect, the thickness of the first semiconductor layer is represented by T [μm], and the OA diameter of the light-emitting element including the first DBR, the active layer, the second DBR, and the first semiconductor layer is D ＯＡ When expressed in [μm], T > 0.405√D ＯＡ -2.55 and T ≥ 1 μm may also be satisfied. This allows, for example, a predetermined OA diameter D ＯＡ For a light-emitting element having [a specific characteristic], it becomes possible to set the film thickness T so that suitable emitted light can be obtained.

[0010] Furthermore, in this first aspect, the first semiconductor layer may be an n-type semiconductor layer. This makes it possible, for example, to make the current distribution described above more uniform.

[0011] Furthermore, in this first aspect, the first semiconductor layer may be a compound semiconductor layer. This makes it possible, for example, to realize a first semiconductor layer having low resistivity using a compound semiconductor layer.

[0012] Furthermore, in this first aspect, the first semiconductor layer is a GaAs layer and / or Al ｘ Ga １－ｘ An As layer (where Ga represents gallium, As represents arsenic, Al represents aluminum, and x represents a real number satisfying 0 < x < 0.4) may be included. This allows, for example, a first semiconductor layer having low resistivity to be a GaAs layer or Al ｘ Ga １－ｘ This can be achieved through the As layer.

[0013] Furthermore, the light-emitting device on the first side may further include a second semiconductor layer provided between the active layer and the first semiconductor layer. This makes it possible, for example, to use the second semiconductor layer as a buffer layer.

[0014] Furthermore, in this first aspect, the second semiconductor layer may be a p-type semiconductor layer. This makes it possible to form a PIN structure including, for example, the second semiconductor layer.

[0015] Furthermore, the light-emitting device on the first side may further include a tunnel junction layer provided between the first semiconductor layer and the second semiconductor layer. This makes it possible, for example, to make the polarity of the emission side and the non-emission side of the light-emitting device the same.

[0016] Furthermore, in this first aspect, the tunnel junction layer may be in contact with the first semiconductor layer. This makes it possible, for example, to form the first semiconductor layer by epitaxial growth from the tunnel junction layer.

[0017] Furthermore, in this first aspect, the first semiconductor layer is provided between the second DBR and the active layer, has a resistivity lower than that of the second DBR, the first DBR is an n-type DBR, the second DBR is an n-type DBR, and the light-emitting device may be a surface emission type. This makes it possible, for example, to make the first semiconductor layer an n-type semiconductor layer.

[0018] Furthermore, in this first aspect, the first semiconductor layer is provided between the first DBR and the active layer, has a resistivity lower than that of the first DBR, the first DBR is an n-type DBR, the second DBR is a p-type DBR, and the light-emitting device may be a back-side emission type. This makes it possible, for example, to make the first semiconductor layer a p-type semiconductor layer.

[0019] Furthermore, this first side-emitting device may further include a first electrode provided on the second DBR so as to penetrate the second DBR and in contact with the first semiconductor layer. This makes it possible, for example, to make the second DBR an i-type DBR.

[0020] Furthermore, the first side-emitting device may also include, as the first semiconductor layer, a lower semiconductor layer provided between the active layer and the first DBR and having a resistivity lower than that of the first DBR, and an upper semiconductor layer provided between the active layer and the second DBR and having a resistivity lower than that of the second DBR. This makes it possible, for example, to bring the current distribution within the light-emitting element closer to a more uniform distribution.

[0021] Furthermore, in this first aspect, when the thinner and thicker of the film thicknesses of the lower semiconductor layer and the upper semiconductor layer are represented by Ta and Tb, respectively, the condition Tb × 1 / 4 < Ta < Tb × 3 / 4 may hold. This makes it possible to suppress mode hopping, for example.

[0022] Furthermore, the light-emitting device on the first side may further include a third DBR provided between the first DBR and the active layer, and a fourth DBR provided between the second DBR and the active layer. This makes it possible to realize, for example, a structure in which a plurality of first semiconductor layers are included within the light-emitting element.

[0023] Furthermore, in this first aspect, the third DBR or the fourth DBR includes a plurality of alternately stacked first refractive index layers and a plurality of second refractive index layers, and the number of the plurality of first refractive index layers and the number of the plurality of second refractive index layers may both be five or less. This makes it possible to minimize the influence of the first semiconductor layer on the oscillation wavelength, for example.

[0024] Furthermore, in this first aspect, the optical thickness of the first semiconductor layer may be an integer multiple of half the oscillation wavelength of the light-emitting element including the first DBR, the active layer, the second DBR, and the first semiconductor layer. This makes it possible to obtain suitable emitted light while suppressing interference with oscillation at the intended wavelength, for example.

[0025] Furthermore, in this first aspect, the second DBR may be a dielectric DBR. This makes it possible, for example, to form the second DBR without using a semiconductor.

[0026] Furthermore, this first side-emitting device may further include a step-forming layer provided below the second DBR to form a step. This makes it possible to achieve, for example, light confinement by the step.

[0027] A light-emitting device according to a second aspect of the present disclosure comprises a substrate, a first DBR provided on the substrate, an active layer provided on the first DBR, a second DBR provided on the active layer, and a first semiconductor layer provided between the active layer and the second DBR and having a higher thermal conductivity than the second DBR, or provided between the active layer and the first DBR and having a lower thermal conductivity than the first DBR. This makes it possible to stably generate high power from the light-emitting element. For example, it becomes possible to make the distribution of heat transferred between the second DBR or the first DBR and the first semiconductor layer closer to a uniform distribution within the first semiconductor layer, thereby improving the light emission profile of the light emitted from the light-emitting element.

[0028] This is a cross-sectional view showing the structure of the light-emitting device of the first embodiment. This is a cross-sectional view showing the structure of the light-emitting device of the first comparative example of the first embodiment. This is a cross-sectional view showing the structure of the light-emitting device of the second comparative example of the first embodiment. This is another cross-sectional view showing the structure of the light-emitting device of the first embodiment. This is a graph for explaining the operation of the light-emitting device of the first embodiment. This is another graph for explaining the operation of the light-emitting device of the first embodiment. This is a cross-sectional view showing the structure of the light-emitting device of the second embodiment. This is a cross-sectional view showing the structure of the light-emitting device of the third embodiment. This is a cross-sectional view showing the structure of the light-emitting device of the fourth embodiment. This is a plan view showing the structure of the light-emitting device of the fourth embodiment. This is a cross-sectional view showing the structure of the light-emitting device of the fifth embodiment. This is a cross-sectional view showing the structure of the light-emitting device of the sixth embodiment. This is a plan view showing the structure of the light-emitting device of the sixth embodiment. This is a block diagram showing an example of the configuration of the distance measuring device of the seventh embodiment. This is a diagram for explaining the STL method of the seventh embodiment. This is a block diagram showing the configuration of the vehicle of the eighth embodiment. This is a plan view showing the sensing area of ​​the vehicle of the eighth embodiment.

[0029] Hereinafter, embodiments of this disclosure will be described with reference to the drawings.

[0030] (First Embodiment) Figure 1 is a cross-sectional view showing the structure of the light-emitting device of the first embodiment.

[0031] The light-emitting device of this embodiment is, for example, a surface-emitting VCSEL light-emitting device. FIG. 1 shows one light-emitting element in the light-emitting device of this embodiment.

[0032] The light-emitting device of this embodiment includes, as components of the light-emitting element shown in FIG. 1, a substrate 1, a lower DBR (Distributed Bragg Reflector) 2, a stacked film 3, a low-resistance semiconductor layer 4, an upper DBR 5, a contact layer 6, an upper electrode 11, a passivation film 12, an anode electrode 13, and a cathode electrode 14. The stacked film 3 includes an active layer 3a, an oxide layer 3b, a non-oxide layer 3b', a buffer layer 3c, and a tunnel junction (TJ) layer 3d. The lower DBR 2 is an example of the first DBR of the present disclosure, and the upper DBR 5 is an example of the second DBR of the present disclosure. The low-resistance semiconductor layer 4 is an example of the first semiconductor layer of the present disclosure, and the buffer layer 3c is an example of the second semiconductor layer of the present disclosure.

[0033] FIG. 1 shows an X-axis, a Y-axis, and a Z-axis that are perpendicular to each other. The X direction and the Y direction correspond to the lateral direction (horizontal direction), and the Z direction corresponds to the longitudinal direction (vertical direction). Also, the +Z direction corresponds to the upward direction, and the -Z direction corresponds to the downward direction. The -Z direction may exactly coincide with the gravitational direction or may not exactly coincide with the gravitational direction.

[0034] [Substrate 1] The substrate 1 is, for example, a semiconductor substrate such as an n-type GaAs (gallium arsenide) substrate. In FIG. 1, the surface S1 of the substrate 1 is the upper surface of the substrate 1, and the back surface S2 of the substrate 1 is the lower surface of the substrate 1. In FIG. 1, further, the X direction and the Y direction are parallel to the surface S1 and the back surface S2 of the substrate 1, and the Z direction is perpendicular to the surface S1 and the back surface S2 of the substrate 1.

[0035] [Lower DBR 2] The lower DBR 2 is formed on the substrate 1. The lower DBR 2 is, for example, an n-type semiconductor layer (n-type DBR). The lower DBR 2 of this embodiment includes a plurality of low-refractive-index layers and a plurality of high-refractive-index layers alternately stacked on the substrate 1.

[0036] [Stacked film 3] The stacked film 3 is formed on the lower DBR 2 and is included in the mesa M of the light-emitting element. The mesa M has, for example, a circular shape in plan view. The diameter of the mesa M in plan view is, for example, 70 μm. The mesa M may have a quadrangular (e.g., square or rectangular), triangular, hexagonal, or other polygonal shape in plan view.

[0037] The stacked film 3 includes an active layer 3a, an oxidation layer 3b, a buffer layer 3c, and a TJ layer 3d that are sequentially stacked on the lower DBR 2. The active layer 3a has a quantum well structure and specifically includes a plurality of quantum well layers and a plurality of barrier layers that are alternately stacked so as to have compressive strain. The oxidation layer 3b is formed, for example, by steam-oxidizing an AlAs (aluminum arsenide) layer. The buffer layer 3c is, for example, a p-type semiconductor layer. The TJ layer 3d includes, for example, a highly doped p-type semiconductor layer and a highly doped n-type semiconductor layer that are sequentially stacked on the buffer layer 3c.

[0038] The stacked film 3 further includes a non-oxidation layer 3b' formed on the active layer 3a. The non-oxidation layer 3b' is surrounded annularly by the oxidation layer 3b in plan view. Conversely, the oxidation layer 3b is formed around the non-oxidation layer 3b' and surrounds the non-oxidation layer 3b' annularly in plan view. In the present embodiment, the shape of the non-oxidation layer 3b' is generally circular in plan view, and the shape of the oxidation layer 3b is generally annular in plan view.

[0039] The oxidation layer 3b and the non-oxidation layer 3b' are formed, for example, by forming an AlAs layer on the active layer 3a and steam-oxidizing a part of this AlAs layer. In this case, the oxidized part of the AlAs layer becomes the oxidation layer 3b, and the non-oxidized part of the AlAs layer becomes the non-oxidation layer 3b'. The oxidation layer 3b and the non-oxidation layer 3b' may be a sufficiently oxidized part and a sufficiently non-oxidized part of the AlAs layer. The oxidation layer 3b and the non-oxidation layer 3b' of the present embodiment are formed by steam-oxidizing the AlAs layer from the side surface (end face of the AlAs layer) of the mesa M after the formation of the mesa M.

[0040] Figure 1 shows the emission diameter D of the light-emitting element of the present embodiment. The emission diameter D generally corresponds to the diameter of the laser light generated from the light-emitting element of the present embodiment. The emission diameter D of the present embodiment is determined based on the diameter (OA diameter) of the non-oxidized layer 3b'. In the present embodiment, the diameter of the non-oxidized layer 3b' is set large, and as a result, the emission diameter D is large. When the planar shape of the non-oxidized layer 3b' is other than circular, the emission diameter D is determined based on, for example, the length of the longest or shortest line among the dividing lines (lines parallel to the XY plane) passing through the centroid of the planar shape of the non-oxidized layer 3b'. The emission diameter D and the OA diameter are, for example, 50 μm or more.

[0041] The difference between the radius of the inner side surface and the radius of the outer side surface of the oxidized layer 3b is referred to as the oxidation length of the oxidized layer 3b. The diameter of the outer peripheral side surface of the oxidized layer 3b corresponds to the diameter of the mesa M. On the other hand, the diameter of the inner peripheral side surface of the oxidized layer 3b corresponds to the diameter of the non-oxidized layer 3b.

[0042] [Low-resistance semiconductor layer 4] The low-resistance semiconductor layer 4 is formed on the laminated film 3 and is included in the mesa M of the light-emitting element. The low-resistance semiconductor layer 4 is, for example, an n-type semiconductor layer. The low-resistance semiconductor layer 4 of the present embodiment is a binary or ternary compound semiconductor layer. The binary compound semiconductor layer is, for example, a GaAs layer. The ternary compound semiconductor layer is, for example, an Al ｘ Ga １－ｘ As layer (Ga represents gallium, As represents arsenic, Al represents aluminum, and x represents a real number satisfying 0 < x < 0.4). The low-resistance semiconductor layer 4 may include both a binary compound semiconductor layer and a ternary compound semiconductor layer, or may include an N-element (N is an integer of 4 or more) compound semiconductor layer. The low-resistance semiconductor layer 4 of the present embodiment is in contact with the TJ layer 3d and is formed by epitaxial growth from the TJ layer 3d. The film thickness of the low-resistance semiconductor layer 4 is, for example, 1 μm or more.

[0043] In this embodiment, the low-resistance semiconductor layer 4 is provided between the active layer 3a and the upper DBR 5, and has a lower resistivity than the upper DBR 5. As a result, the current flowing from the upper electrode 11 to the laminated film 3 through the upper DBR 5 and the low-resistance semiconductor layer 4 is more easily diffused laterally within the low-resistance semiconductor layer 4 than within the upper DBR 5. This makes it possible to bring the distribution of current flowing within the upper DBR 5 and the low-resistance semiconductor layer 4 closer to a uniform distribution within the low-resistance semiconductor layer 4, thereby improving the light emission profile of the light emitted from the light-emitting element. Further details of these effects will be described later.

[0044] If the low-resistance semiconductor layer 4 is formed from two or more materials, the resistivity of the low-resistance semiconductor layer 4 described above shall be the average resistivity of the low-resistance semiconductor layer 4. For example, if the electrical resistance, area, and film thickness of the low-resistance semiconductor layer 4 are expressed by R, S, and d, respectively, the average resistivity of the low-resistance semiconductor layer 4 is given by RS / d. Similarly, if the upper DBR 5 is formed from two or more materials, the resistivity of the upper DBR 5 described above shall be the average resistivity of the upper DBR 5.

[0045] [Upper DBR5] The upper DBR5 is formed on the low-resistance semiconductor layer 4 and is included in the mesa M of the light-emitting element. The upper DBR5 is, for example, an n-type semiconductor layer (n-type DBR). In this embodiment, the upper DBR5 includes a plurality of low-refractive-index layers and a plurality of high-refractive-index layers alternately stacked on the low-resistance semiconductor layer 4.

[0046] [Contact Layer 6] The contact layer 6 is formed on the upper DBR 5 and is included in the mesa M of the light-emitting element. In Figure 1, the contact layer 6 is the underlying layer of the upper electrode 11. The contact layer 6 is an n-type semiconductor layer, such as an n-type polysilicon layer. In this case, the contact layer 6 is also called an n-type current injection layer.

[0047] [Upper electrode 11] The upper electrode 11 is formed on the contact layer 6. In this embodiment, the upper electrode 11 has an annular shape in plan view. In this embodiment, the diameter of the inner side surface of the upper electrode 11 is set to be larger than the diameter of the non-oxidized layer 3b' (OA diameter), and the diameter of the outer side surface of the upper electrode 11 is set to be smaller than the diameter of the contact layer 6. The upper electrode 11 is, for example, an n-type semiconductor layer.

[0048] [Passivation film 12] The passivation film 12 is formed on the lower DBR 2, the multilayer film 3, the low-resistance semiconductor layer 4, the upper DBR 5, the contact layer 6, and the side and upper surfaces of the upper electrode 11. However, the passivation film 12 has an opening on the upper surface of the upper electrode 11. The passivation film 12 is an insulating film such as a SiN (silicon nitride) film.

[0049] [Anode Electrode 13] The anode electrode 13 is formed on the passivation film 12 and is also formed on the upper electrode 11 through an opening in the passivation film 12. In this way, the anode electrode 13 is electrically connected to the light-emitting element of this embodiment. The anode electrode 13 is, for example, a metal electrode formed by a plating method.

[0050] The anode electrode 13 has an opening above the multilayer film 3, the low-resistance semiconductor layer 4, the upper DBR 5, and the contact layer 6. In this embodiment, the opening of the anode electrode 13 has a circular shape in plan view. In this embodiment, the diameter of the opening of the anode electrode 13 is set to be larger than the diameter (OA diameter) of the non-oxidized layer 3b'.

[0051] [Cathode electrode 14] The cathode electrode 14 is formed on the back surface S2 of the substrate 1. Thus, the cathode electrode 14 is electrically connected to the light-emitting element of this embodiment. The cathode electrode 14 is, for example, a metal electrode formed by a plating method.

[0052] Furthermore, the light-emitting device of this embodiment may include a plurality of laminated films 3 stacked in the Z direction between the lower DBR 2 and the low-resistance semiconductor layer 4. This makes it possible to realize MJ-VCSEL.

[0053] Furthermore, the light-emitting device of this embodiment may include a plurality of light-emitting elements arranged in a one-dimensional array or a two-dimensional array. In this case, each of these light-emitting elements may have the structure shown in Figure 1.

[0054] Figure 2 is a cross-sectional view showing the structure of the light-emitting device of the first comparative example of the first embodiment.

[0055] The light-emitting device of this comparative example (Figure 2) has the same structure as the light-emitting device of the first embodiment (Figure 1). However, the light-emitting device of this comparative example does not have a TJ layer 3d or a low-resistance semiconductor layer 4. Also, the upper DBR 5, contact layer 6, and upper electrode 11 of this comparative example are p-type semiconductor layers.

[0056] Figure 2 shows two current paths P1 and P2 flowing from the upper electrode 11 through the upper DBR 5 to the laminated film 3. The current flowing through path P1 is directed from the upper electrode 11 towards the outer periphery of the laminated film 3. The current flowing through path P2 is directed from the upper electrode 11 towards the central part of the laminated film 3.

[0057] As the OA diameter of the mesa M increases, the difference between the resistance of path P1 and path P2 increases, resulting in a larger difference between the current flowing through path P1 and the current flowing through path P2. In Figure 2, the thick arrow representing path P1 indicates a large current flowing through path P1, and the thin arrow representing path P2 indicates a small current flowing through path P2. In this comparative example, the distribution of current flowing within the upper DBR 5 becomes non-uniform, and the intensity of light emitted from the light-emitting element differs significantly between the central and peripheral parts of the mesa M. As a result, higher-order mode oscillation and donut-shaped near-field image problems may occur.

[0058] Figure 3 is a cross-sectional view showing the structure of a light-emitting device of a second comparative example of the first embodiment.

[0059] The light-emitting device of this comparative example (Figure 3) has the same structure as the light-emitting device of the first embodiment (Figure 1). However, the light-emitting device of this comparative example does not have a TJ layer 3d. Also, the low-resistance semiconductor layer 4, upper DBR 5, contact layer 6, and upper electrode 11 of this comparative example are p-type semiconductor layers.

[0060] In this comparative example, the low-resistance semiconductor layer 4 is provided between the active layer 3a and the upper DBR 5, and has a lower resistivity than the upper DBR 5. As a result, the current flowing from the upper electrode 11 to the laminated film 3 via the upper DBR 5 and the low-resistance semiconductor layer 4 is more easily diffused laterally within the low-resistance semiconductor layer 4 than within the upper DBR 5. This is because the current path becomes shorter within the upper DBR 5 and longer within the low-resistance semiconductor layer 4, thus reducing the resistance of the current path. For example, the slope of path P2 with respect to the Z direction is smaller within the upper DBR 5 and larger within the low-resistance semiconductor layer 4. As a result, the difference between the current flowing through path P1 and the current flowing through path P2 becomes smaller. This makes it possible to bring the distribution of current flowing within the upper DBR 5 and the low-resistance semiconductor layer 4 closer to a uniform distribution within the low-resistance semiconductor layer 4, thereby improving the light emission profile of the light emitted from the light-emitting element.

[0061] Figure 4 is another cross-sectional view showing the structure of the light-emitting device of the first embodiment.

[0062] As described above, the laminated film 3 of this embodiment includes a TJ layer 3d, etc. Furthermore, the low-resistance semiconductor layer 4, upper DBR 5, contact layer 6, and upper electrode 11 of this embodiment are n-type semiconductor layers.

[0063] According to the second comparative example, by providing a low-resistance semiconductor layer 4 between the active layer 3a and the upper DBR 5, it is possible to improve the light emission profile of the light emitted from the light-emitting element. However, since the low-resistance semiconductor layer 4 in the second comparative example is a p-type semiconductor layer, it is difficult to sufficiently lower the resistance of the low-resistance semiconductor layer 4.

[0064] Therefore, in this embodiment, the low-resistance semiconductor layer 4 provided between the active layer 3a and the upper DBR 5 is an n-type semiconductor layer. This makes it possible to sufficiently lower the resistance of the low-resistance semiconductor layer 4, and to bring the distribution of current flowing through the upper DBR 5 and the low-resistance semiconductor layer 4 closer to a more uniform distribution within the low-resistance semiconductor layer 4. The reason is that the resistivity of an n-type semiconductor layer is generally lower than that of a p-type semiconductor layer. According to this embodiment, by providing an n-type semiconductor layer as the low-resistance semiconductor layer 4 between the active layer 3a and the upper DBR 5, it is possible to further improve the light emission profile of the light emitted from the light-emitting element. In Figure 4, the arrow representing path P2 is thicker, which indicates that the current flowing through path P2 is large.

[0065] Furthermore, if the emission profile of the emitted light can be sufficiently improved by adopting the second comparative example instead of the first embodiment, the low-resistance semiconductor layer 4 may be a p-type semiconductor layer instead of an n-type semiconductor layer. In this case, the light-emitting device of the second comparative example corresponds to the light-emitting device of a modified version of the first embodiment.

[0066] Figure 5 is a graph illustrating the operation of the light-emitting device of the first embodiment.

[0067] The horizontal axis of Figure 5 shows the position of the mesa M from the central axis within the low-resistance semiconductor layer 4, and the vertical axis of Figure 5 shows the current density at that position. Figure 5 shows the relationship between position and current density for low-resistance semiconductor layer 4 (n-type semiconductor layer) thicknesses of 0.5 μm, 1.5 μm, 3.0 μm, and 5.0 μm. For reference, Figure 5 also shows the relationship between position and current density for the case where the low-resistance semiconductor layer 4 is a p-type semiconductor layer. Figure 5 shows the simulation results for the case where the OA diameter of the mesa M is 50 μm.

[0068] As shown in Figure 5, when the low-resistance semiconductor layer 4 is a p-type semiconductor layer, even if the thickness of the low-resistance semiconductor layer 4 is increased to 5.0 μm, the current density changes significantly depending on the position between 0 and 25 μm. On the other hand, when the low-resistance semiconductor layer 4 is an n-type semiconductor layer, even if the thickness of the low-resistance semiconductor layer 4 is reduced to 0.5 μm, the current density does not change much depending on the position between 0 and 25 μm. From this, it can be seen that by making the low-resistance semiconductor layer 4 an n-type semiconductor layer, the distribution of current flowing within the low-resistance semiconductor layer 4 can be made closer to a uniform distribution.

[0069] Figure 6 is another graph illustrating the operation of the light-emitting device of the first embodiment.

[0070] The horizontal axis of Figure 6 represents the OA diameter of the mesa M, and the vertical axis of Figure 6 represents the film thickness of the low-resistance semiconductor layer 4 when the ratio of the peak current value to the median current value within the low-resistance semiconductor layer 4 is 0.9. The peak current value is the current density value at the position where the current density is maximum within the low-resistance semiconductor layer 4. The median current value is the current density value at the position on the central axis of the mesa M within the low-resistance semiconductor layer 4. In Figure 6, the horizontal axis of the OA diameter is "D ＯＡ The values ​​are expressed in [μm], and the film thickness on the vertical axis is represented by "T [μm]". Figure 6 shows the simulation results for cases where the OA diameter has various values.

[0071] In Figure 6, curve C1 shows the relationship between the OA diameter and film thickness when the light-emitting device has a DBR between the active layer 3a and the low-resistance semiconductor layer 4, and curve C2 shows the relationship between the OA diameter and film thickness when the light-emitting device does not have a DBR between the active layer 3a and the low-resistance semiconductor layer 4. The light-emitting device of this embodiment does not have a DBR between the active layer 3a and the low-resistance semiconductor layer 4, and therefore has the characteristics of curve C2. On the other hand, the light-emitting device of the fourth embodiment, which will be described later, has a DBR between the active layer 3a and the low-resistance semiconductor layer 4, and therefore has the characteristics of curve C1. This DBR alternately includes K low-refractive-index layers and K high-refractive-index layers, where K is, for example, 3.

[0072] Curves C1 and C2 were obtained by fitting multiple plots obtained from simulations. Curve C1 is obtained at T = 0.405√D ＯＡIt is expressed by the equation -2.55. The curve C2 is given by T = 0.572√D ＯＡ It is expressed by the equation -2.65. Figure 6 shows the region R1 below curve C1, the region R2 between curve C1 and curve C2, and the region R3 above curve C2.

[0073] The light-emitting device of this embodiment preferably has characteristics on the upper side of curve C1, i.e., characteristics within region R2 or region R3. In other words, the light-emitting device of this embodiment has T > 0.405√D ＯＡ It is desirable that the design satisfy the equation -2.55. This makes it possible to bring the current distribution flowing through the low-resistance semiconductor layer 4 closer to a sufficiently uniform distribution. Also, the curve C1 in Figure 6 is given in the range of T ≥ 1 μm, and therefore, the light-emitting device of this embodiment has T > 0.405√D ＯＡ It is desirable that the design be such that equation -2.55 and the equation for T ≥ 1 μm hold true.

[0074] Furthermore, it is desirable that the light-emitting device of this embodiment has characteristics on the upper side of curve C2, i.e., characteristics within region R3. In other words, the light-emitting device of this embodiment has T > 0.572√D ＯＡ It is desirable that the design be such that equation -2.65 holds true. This makes it possible to bring the current distribution flowing through the low-resistance semiconductor layer 4 closer to a sufficiently uniform distribution, even without providing a DBR between the active layer 3a and the low-resistance semiconductor layer 4. However, the characteristics in region R3 may be adopted when a DBR is provided between the active layer 3a and the low-resistance semiconductor layer 4, and conversely, the characteristics in region R2 may be adopted when a DBR is not provided between the active layer 3a and the low-resistance semiconductor layer 4.

[0075] Note that T > 0.405√D ＯＡ The equation is -2.55, and T > 0.572√D ＯＡ The formula for -2.65 is OA diameter D ＯＡ The equation may hold not only for [μm] but also for the luminescence diameter D [μm]. That is, in this embodiment, the equations T > 0.405√D - 2.55 and T > 0.572√D - 2.65 may also hold.

[0076] As described above, the light-emitting device of this embodiment includes a low-resistance semiconductor layer 4 between the active layer 3a and the upper DBR 5. The low-resistance semiconductor layer 4 of this embodiment is an n-type semiconductor layer and has a resistivity lower than that of the upper DBR 5. Therefore, according to this embodiment, it is possible to stably generate high output from the light-emitting element. For example, it is possible to make the distribution of current flowing through the low-resistance semiconductor layer 4 closer to a uniform distribution, and it is possible to improve the light emission profile of the light emitted from the light-emitting element.

[0077] Furthermore, the low-resistance semiconductor layer 4 of this embodiment may have not only a resistivity lower than that of the upper DBR 5, but also a thermal conductivity higher than that of the upper DBR 5. This makes it possible to diffuse not only current laterally within the low-resistance semiconductor layer 4, but also heat laterally within the low-resistance semiconductor layer 4. As a result, it is possible to suppress not only the adverse effect of current characteristics on the light emission profile, but also the adverse effect of thermal characteristics on the light emission profile. In other words, the semiconductor layer 4 of this embodiment may be a high-heat-transfer semiconductor layer, not just a low-resistance semiconductor layer. Also, the semiconductor layer 4 of this embodiment may have only one of either a resistivity lower than that of the upper DBR 5 or a thermal conductivity higher than that of the upper DBR 5. Furthermore, if the semiconductor layer 4 is formed from two or more materials, or if the upper DBR 5 is formed from two or more materials, the thermal conductivity described above shall be the average thermal conductivity, similar to how the resistivity described above is defined as the average resistivity.

[0078] (Second Embodiment) Figure 7 is a cross-sectional view showing the structure of the light-emitting device of the second embodiment.

[0079] The light-emitting device of this embodiment is, for example, a back-side emission type VCSEL light-emitting device. Figure 7 shows one light-emitting element within the light-emitting device of this embodiment.

[0080] The light-emitting device of this embodiment (Figure 7) has the same structure as the light-emitting device of the first embodiment (Figure 1). However, the light-emitting device of this embodiment does not have a TJ layer 3d, and instead has a lower electrode 15 and an AR (Anti-Reflection) coating film 16. Also, the upper DBR 5, contact layer 6, and upper electrode 11 of this embodiment are p-type semiconductor layers. The differences between this embodiment and the first embodiment will be described in detail below.

[0081] [Substrate 1] The substrate 1 in this embodiment is, for example, an SI (Semi-Insulating) substrate. An example of this SI substrate is a semiconductor substrate such as an i-type GaAs substrate. In this embodiment, since the light emitted from the mesa M passes through the substrate 1, an SI substrate with low optical absorption is used.

[0082] [Low-resistance semiconductor layer 4] The low-resistance semiconductor layer 4 of this embodiment is provided between the lower DBR 2 and the laminated film 3 and is not included in the mesa M of the light-emitting element. The low-resistance semiconductor layer 4 of this embodiment is, for example, an n-type semiconductor layer, similar to the low-resistance semiconductor layer 4 of the first embodiment. The low-resistance semiconductor layer 4 of this embodiment is in contact with the lower DBR 2 and is formed by epitaxial growth from the lower DBR 2. The light-emitting device of this embodiment has an intracavity structure in which the lower DBR 2 is provided between the substrate 1 and the low-resistance semiconductor layer 4. The mesa M of this embodiment has, for example, a square shape of 100 μm × 100 μm in plan view.

[0083] In this embodiment, the low-resistivity semiconductor layer 4 is provided between the active layer 3a and the lower DBR 2, and has a lower resistivity than the lower DBR 2. As a result, the current flowing from the lower electrode 15 to the laminated film 3 is more easily diffused laterally within the low-resistivity semiconductor layer 4 than within the lower DBR 2. This makes it possible to bring the distribution of the current flowing within the low-resistivity semiconductor layer 4 closer to a uniform distribution, and to improve the light emission profile of the light emitted from the light-emitting element. The contents described with reference to Figures 5 and 6 are also applicable to the light-emitting device of this embodiment.

[0084] If the low-resistance semiconductor layer 4 is formed from two or more materials, the resistivity of the low-resistance semiconductor layer 4 described above shall be the average resistivity of the low-resistance semiconductor layer 4. For example, if the electrical resistance, area, and film thickness of the low-resistance semiconductor layer 4 are expressed by R, S, and d, respectively, the average resistivity of the low-resistance semiconductor layer 4 is given by RS / d. Similarly, if the lower DBR 2 is formed from two or more materials, the resistivity of the lower DBR 2 described above shall be the average resistivity of the lower DBR 2.

[0085] [Upper electrode 11] The upper electrode 11 in this embodiment has a non-ring shape (solid) rather than a ring shape (hollow) in plan view. The reason is that the light-emitting device in this embodiment is a back-side emission type rather than a front-side emission type.

[0086] [Passivation Film 12] As shown in Figure 7, the passivation film 12 of this embodiment is formed on the side and top surfaces of the low-resistance semiconductor layer 4, the laminated film 3, the upper DBR 5, the contact layer 6, the upper electrode 11, and the lower electrode 15. However, the passivation film 12 of this embodiment has an opening on the upper surface of the upper electrode 11 and an opening on the upper surface of the lower electrode 15.

[0087] [Anode Electrode 13] The anode electrode 13 of this embodiment is formed on the passivation film 12, similar to the anode electrode 13 of the first embodiment, and is formed on the upper electrode 11 via an opening in the passivation film 12. However, the anode electrode 13 of this embodiment does not have an opening above the contact layer 6.

[0088] [Lower electrode 15] The lower electrode 15 is formed on the low-resistance semiconductor layer 4 outside the mesa M of the light-emitting element. The lower electrode 15 is, for example, an n-type semiconductor layer.

[0089] [Cathode Electrode 14] The cathode electrode 14 in this embodiment is formed on the passivation film 12 outside the mesa M of the light-emitting element, and is also formed on the lower electrode 15 through an opening in the passivation film 12. As a result, the cathode electrode 14 is electrically connected to the light-emitting element of this embodiment. The cathode electrode 14 in this embodiment is, for example, a metal electrode formed by a plating method.

[0090] [AR coating film 16] The AR coating film 16 is formed on the back surface S2 of the substrate 1. The AR coating film 16 in this embodiment is made of a material that does not absorb light having a wavelength corresponding to the oscillation wavelength of the light-emitting element of this embodiment.

[0091] As described above, the light-emitting device of this embodiment includes a low-resistance semiconductor layer 4 between the active layer 3a and the lower DBR 2. The low-resistance semiconductor layer 4 of this embodiment is an n-type semiconductor layer and has a resistivity lower than that of the lower DBR 2. Therefore, according to this embodiment, it is possible to stably generate high output from the light-emitting element. For example, it is possible to make the distribution of current flowing through the low-resistance semiconductor layer 4 closer to a uniform distribution, and it is possible to improve the light emission profile of the light emitted from the light-emitting element.

[0092] Furthermore, the low-resistance semiconductor layer 4 of this embodiment may have not only a resistivity lower than the resistivity of the lower DBR2, but also a thermal conductivity higher than the thermal conductivity of the lower DBR2. This makes it possible to diffuse not only current laterally within the low-resistance semiconductor layer 4, but also heat laterally within the low-resistance semiconductor layer 4. As a result, it is possible to suppress not only the adverse effect of current characteristics on the light emission profile, but also the adverse effect of thermal characteristics on the light emission profile. In other words, the semiconductor layer 4 of this embodiment may be a high-heat-transfer semiconductor layer, not just a low-resistance semiconductor layer. Also, the semiconductor layer 4 of this embodiment may have only one of either a resistivity lower than the resistivity of the lower DBR2 or a thermal conductivity higher than the thermal conductivity of the lower DBR2. Furthermore, if the semiconductor layer 4 is formed from two or more types of materials, or if the lower DBR2 is formed from two or more types of materials, the thermal conductivity described above shall be the average thermal conductivity, similar to how the resistivity described above is defined as the average resistivity.

[0093] (Third Embodiment) Figure 8 is a cross-sectional view showing the structure of the light-emitting device of the third embodiment.

[0094] The light-emitting device of this embodiment is, for example, a surface-emitting type VCSEL light-emitting device. Figure 8 shows one light-emitting element within the light-emitting device of this embodiment.

[0095] The light-emitting device of this embodiment (Figure 8) has the same structure as the light-emitting device of the first embodiment (Figure 1). However, the light-emitting device of this embodiment includes a phase adjustment layer 6' instead of a contact layer 6. Also, the upper DBR 5 and the phase adjustment layer 6' of this embodiment are i-type semiconductor layers. The differences between this embodiment and the first embodiment will be described in detail below.

[0096] [Upper Electrode 11] The upper electrode 11 of this embodiment includes a portion 11a formed on the upper surface of the phase adjustment layer 6' and a portion 11b formed in a through hole that penetrates the phase adjustment layer 6' and the upper DBR 5 in the Z direction. Therefore, the upper electrode 11 of this embodiment is formed on the phase adjustment layer 6' so as to penetrate the phase adjustment layer 6' and the upper DBR 5. The portion 11b is formed on the side surface of the phase adjustment layer 6' and the upper DBR 5 and on the upper surface of the low-resistance semiconductor layer 4, and is in contact with the low-resistance semiconductor layer 4. The upper electrode 11 of this embodiment is, for example, an n-type semiconductor layer. The upper electrode 11 is an example of the first electrode of this disclosure.

[0097] The through-hole has, for example, an annular shape in plan view. In this embodiment, the diameter of the inner side surface of the through-hole is set to be larger than the diameter of the non-oxidized layer 3b' (OA diameter), and the diameter of the outer side surface of the through-hole is set to be smaller than the diameter of the mesa M.

[0098] [Anode Electrode 13] The anode electrode 13 of this embodiment includes a portion 13a formed outside the through-hole and a portion 13b formed inside the through-hole. The portion 13b is formed on the side surface of the phase adjustment layer 6' and the upper DBR 5 and on the upper surface of the low-resistance semiconductor layer 4 via a portion 11b. The anode electrode 13 of this embodiment is, for example, a metal electrode formed by a plating method.

[0099] In this embodiment, since the upper electrode 11 is in contact with the low-resistivity semiconductor layer 4, the current flowing from the upper electrode 11 to the laminated film 3 can flow without passing through the upper DBR 5. This makes it possible to suppress the adverse effects of the high resistivity of the upper DBR 5 on the current and emitted light.

[0100] In this embodiment, the upper DBR5 is an i-type semiconductor layer, not an n-type semiconductor layer. The reason is that the current flowing from the upper electrode 11 to the laminated film 3 can flow without passing through the upper DBR5, so there is no need to lower the resistivity of the upper DBR5. Conversely, according to this embodiment, by making the upper DBR5 an i-type semiconductor layer, it is possible to reduce optical absorption in the upper DBR5.

[0101] The same applies to the phase adjustment layer 6'. According to this embodiment, by setting the refractive index of the phase adjustment layer 6' to a desired value, it becomes possible to adjust the phase of the light emitted from the light-emitting element.

[0102] According to this embodiment, similar to the first embodiment, it is possible to stably generate high output from a surface-emitting type light-emitting element.

[0103] (Fourth Embodiment) Figure 9 is a cross-sectional view showing the structure of the light-emitting device of the fourth embodiment.

[0104] The light-emitting device of this embodiment is, for example, a back-side emission type VCSEL light-emitting device. Figure 9 shows one light-emitting element within the light-emitting device of this embodiment.

[0105] The light-emitting device of this embodiment (Figure 9) has the same structure as the light-emitting device of the second embodiment (Figure 7). However, the light-emitting device of the second embodiment does not have a TJ layer 3d, whereas the light-emitting device of this embodiment does not have an oxide layer 3b, a non-oxidation layer 3b', and a contact layer 6. Furthermore, the light-emitting device of this embodiment includes a lower semiconductor layer 4-1 and an upper semiconductor layer 4-2 as the low-resistance semiconductor layer 4. Furthermore, the light-emitting device of this embodiment includes a lower DBR 7 which is different from the lower DBR 2, an upper DBR 8 which is different from the upper DBR 5, and a step-forming layer 9 which includes a plurality of parts 9a that are separated from each other. In this embodiment, the lower DBR 2, lower semiconductor layer 4-1, upper semiconductor layer 4-2, lower DBR 7, upper DBR 8, upper electrode 11, and lower electrode 15 are all n-type semiconductor layers, and the upper DBR 5 in this embodiment is a dielectric layer (dielectric DBR). Lower DBR7 is an example of the third DBR of this disclosure, and upper DBR8 is an example of the fourth DBR of this disclosure.

[0106] The differences between this embodiment and the second embodiment will be described in detail below. Figure 10 will also be referred to as appropriate in this description. Figure 10 is a plan view showing the structure of the light-emitting device of the fourth embodiment.

[0107] [Lower Semiconductor Layer 4-1] The lower semiconductor layer 4-1 is provided between the lower DBR2 and the lower DBR7 and is not included in the mesa M of the light-emitting element. Details of the lower semiconductor layer 4-1 in this embodiment are the same as those of the low-resistivity semiconductor layer 4 in the second embodiment. However, it is desirable that the lower semiconductor layer 4-1 in this embodiment has a resistivity lower than that of the lower DBR2 and a resistivity lower than that of the lower DBR7. This is because the lower DBR7 is provided between the lower semiconductor layer 4-1 and the laminated film 3. The above description regarding the resistivity, average resistivity, thermal conductivity, and average thermal conductivity of the lower DBR2 and the low-resistivity semiconductor layer 4 is also applicable to the lower DBR2, lower semiconductor layer 4-1, and lower DBR7 in this embodiment.

[0108] [Upper Semiconductor Layer 4-2] The upper semiconductor layer 4-2 is provided between the upper DBR 5 and the upper DBR 8 and is included in the mesa M of the light-emitting element. Details of the upper semiconductor layer 4-2 in this embodiment are the same as those of the low-resistivity semiconductor layer 4 in the first embodiment. However, it is desirable that the upper semiconductor layer 4-2 in this embodiment has a resistivity lower than that of the upper DBR 5 and a resistivity lower than that of the upper DBR 8. This is because the upper DBR 8 is provided between the upper semiconductor layer 4-2 and the laminated film 3. The above description regarding the resistivity, average resistivity, thermal conductivity, and average thermal conductivity of the upper DBR 5 and the low-resistivity semiconductor layer 4 is also applicable to the upper DBR 5, upper semiconductor layer 4-2, and upper DBR 8 in this embodiment. The upper semiconductor layer 4-2 in this embodiment is in contact with the upper DBR 8 and is formed by epitaxial growth from the upper DBR 8.

[0109] [Lower DBR7] The lower DBR7 is provided between the lower semiconductor layer 4-1 and the diffusion layer 3a. The lower DBR7 is, for example, an n-type semiconductor layer (n-type DBR). The lower DBR7 in this embodiment includes a plurality of low refractive index layers and a plurality of high refractive index layers stacked alternately in the Z direction. In this embodiment, the number of low refractive index layers and the number of high refractive index layers in the lower DBR7 are both 5 or less. In this embodiment, the number of the former and the number of the latter are the same, and the lower DBR7 includes low refractive index layers and high refractive index layers of Na pairs (Na is an integer from 2 to 5). The low refractive index layers and high refractive index layers in the lower DBR7 are examples of the first refractive index layer and second refractive index layer of this disclosure.

[0110] According to this embodiment, by providing a lower DBR7 with a small Na value between the active layer 3a and the lower semiconductor layer 4-1, it is possible to minimize the influence of the lower semiconductor layer 4-1 on the oscillation wavelength. Furthermore, it is desirable that the optical film thickness of the lower semiconductor layer 4-1 in this embodiment be an integer multiple of half the oscillation wavelength of the light-emitting element of this embodiment. This makes it possible to obtain suitable emitted light while suppressing interference with oscillation at the expected wavelength.

[0111] [Upper DBR8] The upper DBR8 is provided between the upper semiconductor layer 4-2 and the TJ layer 3d. The upper DBR8 is, for example, an n-type semiconductor layer (n-type DBR). The upper DBR8 in this embodiment includes a plurality of low refractive index layers and a plurality of high refractive index layers stacked alternately in the Z direction. In this embodiment, the number of low refractive index layers and the number of high refractive index layers in the upper DBR8 are both 5 or less. In this embodiment, the number of the former and the number of the latter are the same, and the upper DBR8 includes Nb pairs of low refractive index layers and high refractive index layers (Nb is an integer from 2 to 5). The low refractive index layers and high refractive index layers in the upper DBR8 are also examples of the first refractive index layer and second refractive index layer of this disclosure.

[0112] According to this embodiment, by providing an upper DBR 8 with a small Nb value between the active layer 3a and the upper semiconductor layer 4-2, it is possible to minimize the influence of the upper semiconductor layer 4-2 on the oscillation wavelength. Furthermore, it is desirable that the optical film thickness of the upper semiconductor layer 4-2 in this embodiment be an integer multiple of half the oscillation wavelength of the light-emitting element of this embodiment. This makes it possible to obtain suitable emitted light while suppressing interference with oscillation at the expected wavelength.

[0113] [Non-implanted region Q1 and implanted region Q2] The mesa M of this embodiment includes a non-implanted region Q1 provided in the central part of the mesa M and an implanted region Q2 provided near the side surface of the mesa M. The implanted region Q2 is a region in which predetermined impurity atoms are implanted, and the non-implanted region Q1 is a region in which the impurity atoms are not implanted. The implanted region Q2 is formed, for example, by implanting impurity atoms into a part of the mesa M from the side surface of the mesa M. Therefore, the implanted region Q2 is formed around the non-implanted region Q1 and surrounds the non-implanted region Q1 in a ring shape in a plan view. The non-implanted region Q1 and the implanted region Q2 of this embodiment are formed within the lower DBR 7, the laminated film 3, the upper DBR 8, and the upper semiconductor layer 4-2. The implanted region Q2 may be a region in which predetermined impurity atoms are sufficiently implanted, and the non-implanted region Q1 may be a region in which the impurity atoms are not sufficiently implanted.

[0114] In this embodiment, the non-impregnated region Q1 and the impregnated region Q2 are a low-resistance region and a high-resistance region, respectively. According to this embodiment, by forming the non-impregnated region Q1 and the impregnated region Q2 instead of the oxide layer 3b and the non-oxidized layer 3b', it is possible to realize a current-constricting structure.

[0115] [Step-forming layer 9] The step-forming layer 9 is formed on the upper semiconductor layer 4-2 and is covered by the upper DBR 5 below the upper DBR 5. The step-forming layer 9 includes a plurality of portions 9a that are separated from each other. These portions 9a protrude in the +Z direction from the upper surface of the upper semiconductor layer 4-2 and form a plurality of steps on the upper semiconductor layer 4-2. In this embodiment, these portions 9a are arranged in a two-dimensional array, for example, in a triangular grid as shown in Figure 10. Figure 10 shows the shapes of the upper semiconductor layer 4-2, the step-forming layer 9, and the upper DBR 5 in a plan view.

[0116] According to this embodiment, a light-confining structure can be realized by forming a step-forming layer 9 that includes a plurality of mutually separated portions 9a. The material of the step-forming layer 9 can be any material that can realize a light-confining structure.

[0117] [Upper electrode 11 and anode electrode 13] The upper electrode 11 in this embodiment is formed on the upper semiconductor layer 4-2 and has an annular shape that surrounds the upper DBR 5 in a plan view. The anode electrode 13 in this embodiment is formed on the passivation film 12 and the upper DBR 5, and is formed on the upper electrode 11 through an opening in the passivation film 12.

[0118] [Lower electrode 15 and cathode electrode 14] The lower electrode 15 of this embodiment is formed on the low-resistance semiconductor layer 4 outside the mesa M and has an annular shape that surrounds the mesa M in a plan view. The cathode electrode 14 of this embodiment is formed on the passivation film 12 outside the mesa M and is formed on the lower electrode 15 through an opening in the passivation film 12.

[0119] According to this embodiment, similar to the second embodiment, it is possible to stably generate high output from a back-side emission type light-emitting element.

[0120] (Fifth Embodiment) Figure 11 is a cross-sectional view showing the structure of the light-emitting device of the fifth embodiment.

[0121] The light-emitting device of this embodiment is, for example, a surface-emitting type VCSEL light-emitting device. Figure 11 shows one light-emitting element within the light-emitting device of this embodiment.

[0122] The light-emitting device of this embodiment (Figure 11) has the same structure as the light-emitting device of the first embodiment (Figure 1). However, the light-emitting device of this embodiment, like the light-emitting device of the fourth embodiment, includes a lower semiconductor layer 4-1 and an upper semiconductor layer 4-2 as the low-resistance semiconductor layer 4. Also, the light-emitting device of this embodiment, like the light-emitting device of the fourth embodiment, includes a lower DBR 7 and an upper DBR 8. Furthermore, the light-emitting device of this embodiment includes a lower electrode 15, a cathode electrode 14, and an anode electrode 13 in the positions of the upper electrode 11, anode electrode 13, and cathode electrode 14 of the first embodiment. The lower DBR 2, lower semiconductor layer 4-1, upper semiconductor layer 4-2, upper DBR 5, contact layer 6, lower DBR 7, upper DBR 8, and lower electrode 15 of this embodiment are all n-type semiconductor layers. The differences between this embodiment and the first embodiment will be described in detail below.

[0123] [Lower Semiconductor Layer 4-1] The lower semiconductor layer 4-1 of this embodiment is provided between the lower DBR2 and the lower DBR7 and is not included in the mesa M of the light-emitting element. The details of the lower semiconductor layer 4-1 of this embodiment are the same as those of the lower semiconductor layer 4-1 of the fourth embodiment.

[0124] [Upper Semiconductor Layer 4-2] The upper semiconductor layer 4-2 of this embodiment is provided between the upper DBR 5 and the upper DBR 8 and is included in the mesa M of the light-emitting element. The details of the upper semiconductor layer 4-2 of this embodiment are the same as those of the upper semiconductor layer 4-2 of the fourth embodiment.

[0125] However, in this embodiment, the film thickness of the upper semiconductor layer 4-2 is different from the film thickness of the lower semiconductor layer 4-1. For example, in Figure 11, it is thicker than the film thickness of the lower semiconductor layer 4-1. Here, the thinner and thicker of the film thicknesses of the lower semiconductor layer 4-1 and the upper semiconductor layer 4-2 are represented by Ta and Tb, respectively (Ta < Tb). In Figure 11, the lower semiconductor layer 4-1 has a film thickness Ta, and the upper semiconductor layer 4-2 has a film thickness Tb. In this embodiment, the film thicknesses Ta and Tb are set such that the equation Tb × 1 / 4 < Ta < Tb × 3 / 4 holds true. That is, the film thickness Ta is greater than 1 / 4 of the film thickness Tb and less than 3 / 4 of the film thickness Tb.

[0126] According to this embodiment, by setting the film thicknesses Ta and Tb in this manner, mode hopping can be suppressed. Specifically, it becomes possible to increase the threshold gain of adjacent modes, making it possible to suppress oscillation of adjacent modes even when the adjacent mode interval is short. According to this embodiment, in a VCSEL that is based on the premise of single mode, it becomes possible to suppress the occurrence of undesirable multimodes.

[0127] [Laminated Film 3] The laminated film 3 of this embodiment includes a TJ layer 3d, a buffer layer 3c, an oxide layer 3b, and an active layer 3a, which are sequentially laminated on the lower DBR 7. Thus, the lamination order of the active layer 3a, oxide layer 3b, buffer layer 3c, and TJ layer 3d in this embodiment is the reverse of the lamination order of the active layer 3a, oxide layer 3b, buffer layer 3c, and TJ layer 3d in the first embodiment. The materials and shapes of the active layer 3a, oxide layer 3b, buffer layer 3c, and TJ layer 3d in this embodiment are the same as in the first embodiment.

[0128] [Lower DBR7] The lower DBR7 of this embodiment is provided between the lower semiconductor layer 4-1 and the TJ layer 3d. The details of the lower DBR7 of this embodiment are the same as those of the lower DBR7 of the fourth embodiment.

[0129] [Upper DBR8] The upper DBR8 of this embodiment is provided between the upper semiconductor layer 4-2 and the diffusion layer 3a. The details of the upper DBR8 of this embodiment are the same as those of the upper DBR8 of the fourth embodiment.

[0130] According to this embodiment, similar to the first embodiment, it is possible to stably generate high output from a surface-emitting light-emitting element. Furthermore, according to this embodiment, by adopting the above-described stacking order in the multilayer film 3, it is possible to realize an anode-common structure instead of a cathode-common structure.

[0131] (Sixth Embodiment) Figure 12 is a cross-sectional view showing the structure of the light-emitting device of the sixth embodiment.

[0132] The light-emitting device of this embodiment is, for example, a surface emission type VCSEL light-emitting device. Figure 12 shows three light-emitting elements (three mesa Ms) within the light-emitting device of this embodiment.

[0133] The light-emitting device of this embodiment comprises a plurality of light-emitting elements arranged in a two-dimensional array, as will be described later. Figure 12 shows three of these light-emitting elements. Each light-emitting element of this embodiment (Figure 12) has the same structure as the light-emitting element of the fifth embodiment (Figure 11). In Figure 12, the three light-emitting elements share the same substrate 1, lower DBR 2, lower semiconductor layer 4-1, passivation film 12, anode electrode 13, and cathode electrode 14.

[0134] Figure 13 is a plan view showing the structure of the light-emitting device according to the sixth embodiment.

[0135] Figure 13 shows 5 x 3 light-emitting elements (5 x 3 mesa Ms) within the light-emitting device of this embodiment. Figure 13 further shows three cathode electrodes 14 within the light-emitting device of this embodiment. In this embodiment, multiple light-emitting elements adjacent to each other in the X direction share the same cathode electrode 14. This makes it possible to drive these light-emitting elements simultaneously with the same cathode electrode 14. Regarding the anode electrode 13, all light-emitting elements within the light-emitting device of this embodiment share the same anode electrode 13.

[0136] According to this embodiment, similar to the first embodiment, it is possible to stably generate high output from a surface-emitting type light-emitting element. Furthermore, according to this embodiment, similar to the fifth embodiment, it is possible to realize an anode common structure instead of a cathode common structure.

[0137] (Seventh Embodiment) (1) Diagram 14 of the configuration of the distance measuring device 101 is a block diagram showing an example of the configuration of the distance measuring device 101 of the seventh embodiment. The distance measuring device 101 of this embodiment is mounted on, for example, an automobile.

[0138] As shown in the figure, the distance measuring device 101 includes a light-emitting unit 102, a drive unit 103, a power supply circuit 104, a light-emitting optical system 105, a light-receiving optical system 106, a light-receiving unit 107, a signal processing unit 108, a control unit 109, and a temperature detection unit 110.

[0139] The light-emitting unit 102 emits light from multiple light sources. In this example, the light-emitting unit 102 has light-emitting elements 102a, each of which is a VCSEL (Vertical Cavity Surface Emitting Laser), and these light-emitting elements 102a are arranged in a predetermined manner, such as a matrix. The light-emitting unit 102 is, for example, a light-emitting device according to any of the first to sixth embodiments.

[0140] The drive unit 103 is configured to have a power supply circuit for driving the light-emitting unit 102.

[0141] The power supply circuit 104 generates a power supply voltage for the drive unit 103 based on an input voltage from, for example, a battery (not shown) provided in the distance measuring device 101. The drive unit 103 drives the light-emitting unit 102 based on this power supply voltage.

[0142] Light emitted from the light-emitting unit 102 is irradiated onto the subject S, which is the object to be measured for distance measurement, via the light-emitting optical system 105. The reflected light from the subject S, thus irradiated, is then incident on the light-receiving surface of the light-receiving unit 107 via the light-receiving optical system 106.

[0143] The light-receiving unit 107 is, for example, a light-receiving element such as a CCD (Charge Coupled Device) sensor or a CMOS (Complementary Metal Oxide Semiconductor) sensor. As described above, it receives reflected light from the subject S incident via the light-receiving optical system 106, converts it into an electrical signal, and outputs it.

[0144] The light receiving unit 107 performs processes such as CDS (Correlated Double Sampling) and AGC (Automatic Gain Control) on the electrical signal obtained by photoelectric conversion of the received light, and further performs A / D (Analog / Digital) conversion. It then outputs the signal as digital data to the subsequent signal processing unit 108.

[0145] Furthermore, the light-receiving unit 107 in this example outputs a frame synchronization signal Fs to the drive unit 103. This enables the drive unit 103 to cause the light-emitting element 102a in the light-emitting unit 102 to emit light at a timing corresponding to the frame period of the light-receiving unit 107.

[0146] The signal processing unit 108 is configured as a signal processing processor, for example, by a DSP (Digital Signal Processor). The signal processing unit 108 performs various signal processing operations on the digital signal input from the light receiving unit 107.

[0147] The control unit 109 is configured to include, 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 103 for controlling the light emission operation by the light emission unit 102, and controls the light receiving operation by the light receiving unit 107.

[0148] The control unit 109 functions as a distance measuring unit 109a. The distance measuring unit 109a measures the distance to the subject S based on a signal input via the signal processing unit 108 (i.e., a signal obtained by receiving reflected light from the subject S). In this example, the distance measuring unit 109a measures the distance to each part of the subject S in order to identify the three-dimensional shape of the subject S.

[0149] The specific distance measurement method used in the distance measuring device 101 will be explained in more detail later.

[0150] The temperature detection unit 110 detects the temperature of the light-emitting unit 102. The temperature detection unit 110 can be configured to perform temperature detection using, for example, a diode.

[0151] In this example, the temperature information detected by the temperature detection unit 110 is supplied to the drive unit 103, which enables the drive unit 103 to drive the light-emitting unit 102 based on the temperature information.

[0152] (2) Regarding the distance measurement method, the distance measurement method used in the distance measuring device 101 can be, for example, the STL (Structured Light) method or the ToF (Time of Flight) method.

[0153] The STL method is a method of measuring distance based on an image of an object S illuminated with light having a predetermined light / dark pattern, such as a dot pattern or a grid pattern.

[0154] Figure 15 is a diagram illustrating the STL method of the seventh embodiment.

[0155] In the STL method, a patterned light Lp, such as the one shown in Figure 15A, is shone onto the subject S. The patterned light Lp is divided into multiple blocks BL, and each block BL is assigned a different dot pattern (the dot patterns do not overlap between blocks BL).

[0156] Figure 15B is an explanatory diagram of the distance measurement principle of the STL method.

[0157] In this example, the wall W and the box BX placed in front of it are considered the subject S, and pattern light Lp is irradiated onto the subject S. In the figure, "G" schematically represents the field of view of the light receiving unit 107.

[0158] Furthermore, in the figure, "BLn" refers to the light of a certain block BL in the pattern light Lp, and "dn" refers to the dot pattern of block BLn projected in the light-receiving image by the light-receiving unit 107.

[0159] Here, if box BX does not exist in front of wall W, the dot pattern of block BLn is projected at the position "dn'" in the diagram in the received image. In other words, the position in which the pattern of block BLn is projected in the received image differs depending on whether box BX is present or not, and specifically, pattern distortion occurs.

[0160] The STL method utilizes the fact that the irradiated pattern is distorted by the object's shape to determine the shape and depth of the subject S. Specifically, it determines the shape and depth of the subject S from the way the pattern is distorted.

[0161] When the STL method is adopted, the light receiving unit 107 is, for example, an IR (Infrared) light receiving unit using a global shutter method. In the case of the STL method, the distance measuring unit 109a controls the drive unit 103 so that the light emitting unit 102 emits pattern light, and also detects pattern distortion in the image signal obtained via the signal processing unit 108, and calculates the distance based on the pattern distortion.

[0162] Next, the Time of Flight (ToF) method measures the distance to an object by detecting the time of flight (time difference) of light emitted from the light-emitting unit 102, reflected by the object, and reaching the light-receiving unit 107.

[0163] 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 unit 107, and the light emitting unit 102 is pulse-driven. In this case, the distance measuring unit 109a calculates the time difference from emission to reception of light emitted from the light emitting unit 102 and received by the light receiving unit 107 based on the signal input via the signal processing unit 108, and calculates the distance to each part of the subject S based on this time difference and the speed of light.

[0164] Furthermore, when adopting the so-called indirect ToF (iToF) method (phase difference method) as the ToF method, the light receiving unit 107 is, for example, a light receiving unit capable of receiving IR.

[0165] In addition, although the light-emitting devices of the first to sixth embodiments are used as light sources for the distance measuring device 101 in the seventh embodiment, they may be used in other ways. For example, the light-emitting devices of these embodiments may be used as light sources for optical equipment such as printers, or as illumination devices.

[0166] (Eighth Embodiment) Figure 16 is a block diagram showing the configuration of a vehicle 20 according to the eighth embodiment. Figure 16 shows an example of the configuration of a vehicle control system 20a, which is an example of a mobile device control system.

[0167] The vehicle control system 20a is installed in the vehicle 20 and performs processing related to vehicle driving assistance and autonomous driving.

[0168] The vehicle control system 20a includes a vehicle control ECU (Electronic Control Unit) 21, a communication unit 22, a map information storage unit 23, a location information acquisition unit 24, an external recognition sensor 25, an in-vehicle sensor 26, a vehicle sensor 27, a memory unit 31, a driving support / autonomous driving control unit 32, a DMS (Driver Monitoring System) 33, an HMI (Human Machine Interface) 34, and a vehicle control unit 35. The external recognition sensor 25 includes, for example, the distance measuring device 101 of the seventh embodiment.

[0169] The vehicle control ECU 21, communication unit 22, map information storage unit 23, location information acquisition unit 24, external recognition sensor 25, in-vehicle sensor 26, vehicle sensor 27, memory unit 31, driving support / autonomous driving control unit 32, driver monitoring system (DMS) 33, human-machine interface (HMI) 34, and vehicle control unit 35 are interconnected and can communicate with each other via a communication network 41. The communication network 41 is composed of an in-vehicle communication network or bus that conforms to digital bidirectional communication standards such as CAN (Controller Area Network), LIN (Local Interconnect Network), LAN (Local Area Network), FlexRay®, and Ethernet®. The communication network 41 may be used differently depending on the type of data being transmitted. For example, CAN may be applied to data related to vehicle control, and Ethernet may be applied to large-capacity data. In addition, the various components of the vehicle control system 20a may be directly connected using wireless communication methods intended for relatively short-range communication, such as Near Field Communication (NFC) or Bluetooth®, without going through the communication network 41.

[0170] In the following, when each part of the vehicle control system 20a communicates via the communication network 41, the description of the communication network 41 will be omitted. For example, when the vehicle control ECU 21 and the communication unit 22 communicate via the communication network 41, it will simply be described as the vehicle control ECU 21 and the communication unit 22 communicating.

[0171] [Vehicle Control ECU 21] The vehicle control ECU 21 is composed of various processors, such as a CPU (Central Processing Unit) and an MPU (Micro Processing Unit). The vehicle control ECU 21 controls the functions of the entire vehicle control system 20a or a part of it.

[0172] [Communication Unit 22] The communication unit 22 communicates with various devices inside and outside the vehicle, other vehicles, servers, base stations, etc., and sends and receives various types of data. At this time, the communication unit 22 can communicate using multiple communication methods.

[0173] A brief explanation will be given regarding the external communication capabilities of the communication unit 22. The communication unit 22 communicates with servers located on an external network (hereinafter referred to as "external servers") via a base station or access point using wireless communication methods such as 5G (fifth-generation mobile communication system), LTE (Long Term Evolution), and DSRC (Dedicated Short Range Communications). The external network with which the communication unit 22 communicates is, for example, the internet, a cloud network, or a network specific to a carrier. The communication method used by the communication unit 22 to the external network is not particularly limited, as long as it is a wireless communication method that enables digital two-way communication at a predetermined communication speed and over a predetermined distance.

[0174] Furthermore, for example, the communication unit 22 can communicate with terminals located near the vehicle using P2P (Peer To Peer) technology. Terminals located near the vehicle include, for example, terminals worn by mobile bodies moving at relatively low speeds such as pedestrians and cyclists, terminals installed in fixed locations such as stores, or MTC (Machine Type Communication) terminals. In addition, the communication unit 22 can also perform V2X communication. V2X communication refers to communication between the vehicle and other vehicles, such as vehicle-to-vehicle communication with other vehicles, vehicle-to-infrastructure communication with roadside devices, etc., vehicle-to-home communication with homes, and vehicle-to-pedestrian communication with terminals carried by pedestrians, etc.

[0175] The communication unit 22 can, for example, receive programs from an external source (over the air) to update the software that controls the operation of the vehicle control system 20a. The communication unit 22 can also receive map information, traffic information, information about the vehicle 20's surroundings, etc., from an external source. Furthermore, for example, the communication unit 22 can transmit information about the vehicle 20 and information about the vehicle 20's surroundings to an external source. Information about the vehicle 20 that the communication unit 22 transmits to an external source includes, for example, data indicating the status of the vehicle 20 and recognition results from the recognition unit 73. Furthermore, for example, the communication unit 22 can perform communications corresponding to vehicle emergency notification systems such as e-Call.

[0176] For example, the communication unit 22 receives electromagnetic waves transmitted by road traffic information communication systems (VICS (Vehicle Information and Communication System) (registered trademark)) such as radio beacons, optical beacons, and FM multiplex broadcasting.

[0177] A brief explanation will be given regarding the communication capabilities of the communication unit 22 with the vehicle interior. The communication unit 22 can communicate with various devices in the vehicle, for example, using wireless communication. The communication unit 22 can communicate wirelessly with devices in the vehicle using communication methods that enable digital bidirectional communication at a predetermined or higher communication speed via wireless communication, such as wireless LAN, Bluetooth, NFC, and WUSB (Wireless USB). Not limited to these, the communication unit 22 can also communicate with various devices in the vehicle using wired communication. For example, the communication unit 22 can communicate with various devices in the vehicle via wired communication through a cable connected to a connection terminal (not shown). The communication unit 22 can communicate with various devices in the vehicle using communication methods that enable digital bidirectional communication at a predetermined or higher communication speed via wired communication, such as USB (Universal Serial Bus), HDMI (High-Definition Multimedia Interface) (registered trademark), and MHL (Mobile High-definition Link).

[0178] Here, "devices inside the vehicle" refers to, for example, devices inside the vehicle that are not connected to the communication network 41. Examples of devices inside the vehicle include mobile devices and wearable devices carried by passengers such as the driver, and information devices that are brought into the vehicle and temporarily installed.

[0179] [Map Information Storage Unit 23] The map information storage unit 23 stores either or both maps acquired from external sources and maps created by the vehicle 20. For example, the map information storage unit 23 stores three-dimensional high-precision maps, global maps with lower precision than high-precision maps but covering a wide area, etc.

[0180] High-precision maps include, for example, dynamic maps, point cloud maps, and vector maps. A dynamic map is, for example, a map consisting of four layers: dynamic information, semi-dynamic information, semi-static information, and static information, and is provided to the vehicle 20 from an external server. A point cloud map is a map composed of point clouds (point cloud data). A vector map is, for example, a map that maps traffic information such as the location of lanes and traffic lights to a point cloud map and is adapted for ADAS (Advanced Driver Assistance System) and AD (Autonomous Driving).

[0181] Point cloud maps and vector maps may be provided from, for example, an external server, or they may be created in the vehicle 20 as maps for matching with a local map (described later) based on sensing results from cameras 51, radar 52, LiDAR 53, etc., and stored in the map information storage unit 23. In addition, if high-precision maps are provided from an external server, in order to reduce communication capacity, map data of, for example, several hundred square meters relating to the planned route that the vehicle 20 will travel is acquired from the external server.

[0182] [Location Information Acquisition Unit 24] The location information acquisition unit 24 receives GNSS (Global Navigation Satellite System) signals from GNSS satellites and acquires location information of the vehicle 20. The acquired location information is supplied to the driving support / automatic driving control unit 32. The location information acquisition unit 24 is not limited to using a method that uses GNSS signals; for example, it may acquire location information using beacons.

[0183] [External Recognition Sensor 25] The external recognition sensor 25 is equipped with various sensors used to recognize the external conditions of the vehicle 20, and supplies sensor data from each sensor to various parts of the vehicle control system 20a. The types and number of sensors equipped in the external recognition sensor 25 are arbitrary.

[0184] For example, the external recognition sensor 25 includes a camera 51, a radar 52, a LiDAR (Light Detection and Ranging, Laser Imaging Detection and Ranging) 53, and an ultrasonic sensor 54. However, the external recognition sensor 25 may also be configured to include one or more of the cameras 51, radar 52, LiDAR 53, and ultrasonic sensor 54. The number of cameras 51, radar 52, LiDAR 53, and ultrasonic sensor 54 is not particularly limited as long as it is a number that can be realistically installed on the vehicle 20. Furthermore, the types of sensors included in the external recognition sensor 25 are not limited to this example, and the external recognition sensor 25 may include other types of sensors. Examples of the sensing areas of each sensor included in the external recognition sensor 25 will be described later.

[0185] The shooting method of camera 51 is not particularly limited. For example, various types of cameras capable of distance measurement, such as ToF (Time Of Flight) cameras, stereo cameras, monocular cameras, and infrared cameras, can be applied to camera 51 as needed. However, camera 51 may also be used simply for acquiring images, regardless of distance measurement.

[0186] Furthermore, for example, the external recognition sensor 25 may include an environmental sensor for detecting the environment relative to the vehicle 20. The environmental sensor is a sensor for detecting the environment such as weather, climate, and brightness, and may include various sensors such as a raindrop sensor, fog sensor, sunshine sensor, snow sensor, and illuminance sensor.

[0187] Furthermore, for example, the external recognition sensor 25 includes a microphone used for detecting sounds around the vehicle 20 and the location of sound sources.

[0188] [In-vehicle sensors 26] The in-vehicle sensors 26 are equipped with various sensors for detecting information inside the vehicle and supply sensor data from each sensor to various parts of the vehicle control system 20a. The types and number of sensors equipped in the in-vehicle sensors 26 are not particularly limited as long as they are of a type and number that can be realistically installed in the vehicle 20.

[0189] For example, the in-vehicle sensor 26 may include one or more sensors from among a camera, radar, seat sensor, steering wheel sensor, microphone, and biosensor. The camera included in the in-vehicle sensor 26 may be a camera with various distance-measuring imaging methods, such as a ToF camera, stereo camera, monocular camera, or infrared camera. However, it is not limited to these, and the camera included in the in-vehicle sensor 26 may simply be for acquiring images, regardless of distance measurement. The biosensor included in the in-vehicle sensor 26 may be installed, for example, on the seat or steering wheel, to detect various biometric information of the driver or other passengers.

[0190] [Vehicle Sensor 27] The vehicle sensor 27 is equipped with various sensors for detecting the state of the vehicle 20 and supplies sensor data from each sensor to various parts of the vehicle control system 20a. The types and number of sensors equipped with the vehicle sensor 27 are not particularly limited as long as they are of a type and number that can be realistically installed on the vehicle 20.

[0191] For example, the vehicle sensor 27 includes a speed sensor, an acceleration sensor, an angular velocity sensor (gyro sensor), and an inertial measurement unit (IMU) that integrates them. For example, the vehicle sensor 27 includes a steering angle sensor for detecting the steering angle of the steering wheel, a yaw rate sensor, an accelerator sensor for detecting the amount of operation of the accelerator pedal, and a brake sensor for detecting the amount of operation of the brake pedal. For example, the vehicle sensor 27 includes a rotation sensor for detecting the rotation speed of the engine or motor, an air pressure sensor for detecting the air pressure of the tires, a slip ratio sensor for detecting the slip ratio of the tires, and a wheel speed sensor for detecting the rotation speed of the wheels. For example, the vehicle sensor 27 includes a battery sensor for detecting the remaining charge and temperature of the battery, and an impact sensor for detecting external impacts.

[0192] [Storage Unit 31] The storage unit 31 includes at least one of a non-volatile storage medium and a volatile storage medium, and stores data and programs. The storage unit 31 is used as, for example, an EEPROM (Electrically Erasable Programmable Read Only Memory) and a RAM (Random Access Memory), and as the storage medium, magnetic storage devices such as HDDs (Hard Disk Drives), semiconductor storage devices, optical storage devices, and magneto-optical storage devices can be applied. The storage unit 31 stores various programs and data used by each part of the vehicle control system 20a. For example, the storage unit 31 is equipped with an EDR (Event Data Recorder) and a DSSAD (Data Storage System for Automated Driving), and stores information about the vehicle 20 before and after an event such as an accident, and information acquired by the in-vehicle sensors 26.

[0193] [Driving Assistance / Automatic Driving Control Unit 32] The driving assistance / automatic driving control unit 32 controls the driving assistance and automatic driving of the vehicle 20. For example, the driving assistance / automatic driving control unit 32 includes an analysis unit 61, an action planning unit 62, and an operation control unit 63.

[0194] The analysis unit 61 performs analysis processing on the vehicle 20 and its surroundings. The analysis unit 61 includes a self-position estimation unit 71, a sensor fusion unit 72, and a recognition unit 73.

[0195] The self-position estimation unit 71 estimates the vehicle 20's position based on sensor data from the external recognition sensor 25 and a high-precision map stored in the map information storage unit 23. For example, the self-position estimation unit 71 generates a local map based on the sensor data from the external recognition sensor 25 and estimates the vehicle 20's position by matching the local map with the high-precision map. The position of the vehicle 20 is based on, for example, the center of the rear wheel relative to the axle.

[0196] Local maps are, for example, three-dimensional high-precision maps or occupancy grid maps created using technologies such as SLAM (Simultaneous Localization and Mapping). Three-dimensional high-precision maps are, for example, the point cloud maps mentioned above. Occupancy grid maps divide the three-dimensional or two-dimensional space around the vehicle 20 into grids of a predetermined size and show the occupancy status of objects on a grid-by-grid basis. The occupancy status of objects is indicated, for example, by the presence or absence of an object or the probability of its existence. Local maps are also used, for example, in the detection and recognition processing of the external conditions of the vehicle 20 by the recognition unit 73.

[0197] The self-position estimation unit 71 may estimate the vehicle 20's own position based on the position information acquired by the position information acquisition unit 24 and the sensor data from the vehicle sensor 27.

[0198] The sensor fusion unit 72 performs sensor fusion processing to obtain new information by combining multiple different types of sensor data (for example, image data supplied from the camera 51 and sensor data supplied from the radar 52). Methods for combining different types of sensor data include integration, fusion, and union.

[0199] The recognition unit 73 performs a detection process to detect the external conditions of the vehicle 20, and a recognition process to recognize the external conditions of the vehicle 20.

[0200] For example, the recognition unit 73 performs detection and recognition processing of the external conditions of the vehicle 20 based on information from the external recognition sensor 25, information from the self-position estimation unit 71, information from the sensor fusion unit 72, etc.

[0201] Specifically, for example, the recognition unit 73 performs detection and recognition processing of objects around the vehicle 20. Object detection processing includes, for example, detecting the presence, size, shape, position, and movement of objects. Object recognition processing includes, for example, recognizing attributes such as the type of object or identifying a specific object. However, detection processing and recognition processing are not necessarily clearly separated and may overlap.

[0202] For example, the recognition unit 73 detects objects around the vehicle 20 by performing clustering, which classifies the point cloud based on sensor data from the radar 52 or LiDAR 53 into clusters of points. This allows the presence, size, shape, and position of objects around the vehicle 20 to be detected.

[0203] For example, the recognition unit 73 detects the movement of objects around the vehicle 20 by performing tracking that follows the movement of clusters of points classified by clustering. This allows the speed and direction of travel (movement vector) of objects around the vehicle 20 to be detected.

[0204] For example, the recognition unit 73 detects or recognizes vehicles, people, bicycles, obstacles, structures, roads, traffic lights, traffic signs, road markings, etc., based on image data supplied from the camera 51. The recognition unit 73 may also recognize the types of objects around the vehicle 20 by performing recognition processing such as semantic segmentation.

[0205] For example, the recognition unit 73 can perform recognition processing of traffic rules around the vehicle 20 based on the map stored in the map information storage unit 23, the self-position estimation result by the self-position estimation unit 71, and the recognition result of objects around the vehicle 20 by the recognition unit 73. Through this processing, the recognition unit 73 can recognize the location and status of traffic lights, the content of traffic signs and road markings, the content of traffic regulations, and the lanes that can be driven on.

[0206] For example, the recognition unit 73 can perform recognition processing of the environment surrounding the vehicle 20. The surrounding environment that the recognition unit 73 is intended to recognize may include weather, temperature, humidity, brightness, and road surface conditions.

[0207] The action planning unit 62 creates an action plan for the vehicle 20. For example, the action planning unit 62 creates an action plan by performing route planning and route following processes.

[0208] Global path planning is the process of planning the general route from the start to the goal. This path planning also includes a process called local path planning, which involves generating a track that allows the vehicle 20 to move safely and smoothly in its vicinity, taking into account the vehicle's motion characteristics along the planned route.

[0209] Route following is the process of planning actions to safely and accurately travel along the route planned by the route planner within the planned time. The action planning unit 62 can, for example, calculate the target speed and target angular velocity of the vehicle 20 based on the results of this route following process.

[0210] The motion control unit 63 controls the operation of the vehicle 20 in order to realize the action plan created by the action planning unit 62.

[0211] For example, the motion control unit 63 controls the steering control unit 81, brake control unit 82, and drive control unit 83, which are included in the vehicle control unit 35 described later, to perform acceleration / deceleration control and direction control so that the vehicle 20 moves along the trajectory calculated by the trajectory plan. For example, the motion control unit 63 performs cooperative control for the purpose of realizing ADAS functions such as collision avoidance or impact mitigation, follow driving, vehicle speed maintenance, collision warning for the vehicle, and lane departure warning for the vehicle. For example, the motion control unit 63 performs cooperative control for the purpose of autonomous driving, such as driving autonomously without driver operation.

[0212] [DMS33] The DMS33 performs driver authentication processing and driver status recognition processing based on sensor data from the in-vehicle sensor 26 and input data input to the HMI34, which will be described later. Examples of driver status to be recognized include physical condition, alertness level, concentration level, fatigue level, gaze direction, intoxication level, driving operation, posture, etc.

[0213] Furthermore, the DMS 33 may perform authentication processing for passengers other than the driver and recognition processing for the status of said passengers. Also, for example, the DMS 33 may perform recognition processing of the conditions inside the vehicle based on sensor data from the in-vehicle sensor 26. Examples of conditions inside the vehicle to be recognized include temperature, humidity, brightness, and odor.

[0214] [HMI34] HMI34 handles the input of various data and instructions, and presents various data to the driver, etc.

[0215] A brief explanation of data input by HMI34 is provided. HMI34 is equipped with input devices for human data input. HMI34 generates input signals based on data and instructions input by the input devices and supplies them to various parts of the vehicle control system 20a. HMI34 is equipped with operators such as touch panels, buttons, switches, and levers as input devices. However, HMI34 may also be equipped with input devices that allow information to be input by methods other than manual operation, such as voice or gestures. Furthermore, HMI34 may use external connection devices such as remote control devices using infrared or radio waves, or mobile or wearable devices that correspond to the operation of the vehicle control system 20a, as input devices.

[0216] A brief overview of data presentation by HMI34 is provided below. HMI34 generates visual, auditory, and tactile information for the occupant or outside the vehicle. HMI34 also performs output control, managing the output, output content, output timing, and output method of each generated piece of information. As visual information, HMI34 generates and outputs information indicated by images and light, such as operation screens, vehicle status displays, warning displays, and monitor images showing the surroundings of the vehicle. HMI34 also generates and outputs auditory information, such as voice guidance, warning sounds, and warning messages. Furthermore, HMI34 generates and outputs tactile information, such as information provided to the occupant's sense of touch through force, vibration, and movement.

[0217] As output devices for visual information output by HMI34, for example, a display device that presents visual information by displaying images itself, or a projector device that presents visual information by projecting images, can be applied. In addition to display devices with ordinary displays, the display device may also be a device that displays visual information within the occupant's field of view, such as a head-up display, a transparent display, or a wearable device equipped with AR (Augmented Reality) functionality. Furthermore, HMI34 can also use display devices provided in the vehicle 20, such as a navigation system, instrument panel, CMS (Camera Monitoring System), electronic mirrors, and lamps, as output devices for visual information output.

[0218] Output devices that HMI34 uses to output auditory information include, for example, audio speakers, headphones, and earphones.

[0219] As an output device for HMI34 to output tactile information, for example, a haptic element using haptic technology can be applied. The haptic element is installed in parts of the vehicle 20 that are in contact with by the occupant, such as the steering wheel and the seat.

[0220] [Vehicle Control Unit 35] The vehicle control unit 35 controls various parts of the vehicle 20. The vehicle control unit 35 includes a steering control unit 81, a brake control unit 82, a drive control unit 83, a body system control unit 84, a light control unit 85, and a horn control unit 86.

[0221] The steering control unit 81 detects and controls the state of the steering system of the vehicle 20. The steering system includes, for example, a steering mechanism with a steering wheel, an electric power steering system, etc. The steering control unit 81 includes, for example, a steering ECU that controls the steering system, an actuator that drives the steering system, etc.

[0222] The brake control unit 82 detects and controls the state of the brake system of the vehicle 20. The brake system includes, for example, a brake mechanism including a brake pedal, an ABS (Antilock Brake System), a regenerative braking mechanism, etc. The brake control unit 82 includes, for example, a brake ECU that controls the brake system, an actuator that drives the brake system, etc.

[0223] The drive control unit 83 detects and controls the state of the vehicle 20's drive system. The drive system includes, for example, an accelerator pedal, a drive force generating device for generating driving force such as an internal combustion engine or drive motor, and a drive force transmission mechanism for transmitting driving force to the wheels. The drive control unit 83 also includes, for example, a drive ECU for controlling the drive system and an actuator for driving the drive system.

[0224] The body system control unit 84 detects and controls the state of the body system of the vehicle 20. The body system includes, for example, a keyless entry system, a smart key system, power window devices, power seats, an air conditioning system, airbags, seat belts, a shift lever, etc. The body system control unit 84 also includes, for example, a body system ECU that controls the body system, actuators that drive the body system, etc.

[0225] The light control unit 85 detects and controls the status of various lights on the vehicle 20. Examples of lights to be controlled include headlights, taillights, fog lights, turn signals, brake lights, projection lights, and bumper displays. The light control unit 85 includes a light ECU for controlling the lights and actuators for driving the lights.

[0226] The horn control unit 86 detects and controls the state of the vehicle's car horn. The horn control unit 86 includes, for example, a horn ECU for controlling the car horn, an actuator for driving the car horn, and so on.

[0227] Figure 17 is a plan view showing the sensing area of ​​the vehicle 20 according to the eighth embodiment. Figure 17 shows an example of the sensing area by the camera 51, radar 52, LiDAR 53, and ultrasonic sensor 54 of the external recognition sensor 25 in Figure 16. In Figure 17, the vehicle 20 is schematically shown as viewed from above, with the left end being the front end of the vehicle 20 and the right end being the rear end of the vehicle 20.

[0228] [Sensing Regions 1-1F, B] Sensing regions 1-1F and 1-1B show examples of sensing regions of the ultrasonic sensor 54. Sensing region 1-1F covers the area around the front end of the vehicle 20 by multiple ultrasonic sensors 54. Sensing region 1-1B covers the area around the rear end of the vehicle 20 by multiple ultrasonic sensors 54.

[0229] The sensing results in sensing area 1-1F and sensing area 1-1B are used, for example, to assist in parking the vehicle 20.

[0230] [Sensing Areas 1-2F, B, L, R] Sensing areas 1-2F to 1-2B show examples of sensing areas for short-range or medium-range radar 52. Sensing area 1-2F covers the area in front of the vehicle 20, further than sensing area 1-1F. Sensing area 1-2B covers the area behind the vehicle 20, further than sensing area 1-1B. Sensing area 1-2L covers the rear area of ​​the left side of the vehicle 20. Sensing area 1-2R covers the rear area of ​​the right side of the vehicle 20.

[0231] The sensing results in sensing regions 1-2F are used, for example, to detect vehicles or pedestrians in front of the vehicle 20. The sensing results in sensing region 1-2B are used, for example, to prevent collisions behind the vehicle 20. The sensing results in sensing regions 1-2L and 1-2R are used, for example, to detect objects in blind spots to the sides of the vehicle 20.

[0232] [Sensing areas 1-3F, B, L, R] Sensing areas 1-3F to 1-3B show examples of sensing areas by the camera 51. Sensing area 1-3F covers the area in front of the vehicle 20, further away than sensing area 1-2F. Sensing area 1-3B covers the area behind the vehicle 20, further away than sensing area 1-2B. Sensing area 1-3L covers the area around the left side of the vehicle 20. Sensing area 1-3R covers the area around the right side of the vehicle 20.

[0233] The sensing results in sensing regions 1-3F can be used, for example, for recognition of traffic lights and traffic signs, lane departure prevention support systems, and automatic headlight control systems. The sensing results in sensing regions 1-3B can be used, for example, for parking assistance and surround view systems. The sensing results in sensing regions 1-3L and 1-3R can be used, for example, for surround view systems.

[0234] [Sensing Region 1-4] Sensing region 1-4 shows an example of the sensing region of LiDAR 53. Sensing region 1-4 covers a position further in front of the vehicle 20 than sensing region 1-3F. On the other hand, the range of sensing region 1-4 is narrower in the left-right direction than sensing region 1-3F.

[0235] The sensing results in sensing regions 1-4 can be used, for example, to detect objects such as surrounding vehicles.

[0236] [Sensing Area 1-5] Sensing area 1-5 shows an example of the sensing area of ​​the long-range radar 52. Sensing area 1-5 covers a position further in front of the vehicle 20 than sensing area 1-4. On the other hand, sensing area 1-5 has a narrower range in the left-right direction than sensing area 1-4.

[0237] The sensing results in sensing areas 1-5 are used, for example, for ACC (Adaptive Cruise Control), emergency braking, collision avoidance, etc.

[0238] Furthermore, the sensing areas of the camera 51, radar 52, LiDAR 53, and ultrasonic sensor 54 included in the external recognition sensor 25 may take various configurations other than those shown in Figure 17. Specifically, the ultrasonic sensor 54 may be configured to sense the sides of the vehicle 20, or the LiDAR 53 may be configured to sense the rear of the vehicle 20. Also, the installation positions of each sensor are not limited to the examples described above. In addition, there may be one or more sensors.

[0239] While embodiments of this disclosure have been described above, these embodiments may be implemented with various modifications without departing from the gist of this disclosure. For example, two or more embodiments may be combined and implemented.

[0240] Furthermore, this disclosure may also take the following form.

[0241] (1) A light-emitting device comprising: a substrate; a first DBR provided on the substrate; an active layer provided on the first DBR; a second DBR provided on the active layer; and a first semiconductor layer provided between the active layer and the second DBR and having a resistivity lower than the resistivity of the second DBR, or provided between the active layer and the first DBR and having a resistivity lower than the resistivity of the first DBR.

[0242] (2) The thickness of the first semiconductor layer is expressed as T [μm], and the OA diameter of the light-emitting element including the first DBR, the active layer, the second DBR, and the first semiconductor layer is D ＯＡ When expressed in [μm], T > 0.405√D ＯＡ The light-emitting device described in (1), wherein -2.55 and T ≥ 1 μm are satisfied.

[0243] (3) The light-emitting apparatus according to (1), wherein the first semiconductor layer is an n-type semiconductor layer.

[0244] (4) The light-emitting apparatus according to (1), wherein the first semiconductor layer is a compound semiconductor layer.

[0245] (5) The first semiconductor layer is a GaAs layer and / or Al ｘ Ga １－ｘ The light-emitting device according to (1), which includes an As layer (where Ga represents gallium, As represents arsenic, Al represents aluminum, and x represents a real number satisfying 0 < x < 0.4).

[0246] (6) The light-emitting apparatus according to (1), further comprising a second semiconductor layer provided between the active layer and the first semiconductor layer.

[0247] (7) The light-emitting apparatus according to (6), wherein the second semiconductor layer is a p-type semiconductor layer.

[0248] (8) The light-emitting apparatus according to (6), further comprising a tunnel junction layer provided between the first semiconductor layer and the second semiconductor layer.

[0249] (9) The light-emitting apparatus according to (8), wherein the tunnel junction layer is in contact with the first semiconductor layer.

[0250] (10) The light-emitting apparatus according to (1), wherein the first semiconductor layer is provided between the second DBR and the active layer and has a resistivity lower than the resistivity of the second DBR, the first DBR is an n-type DBR, the second DBR is an n-type DBR, and the light-emitting apparatus is of the surface emission type.

[0251] (11) The light-emitting device according to (1), wherein the first semiconductor layer is provided between the first DBR and the active layer and has a resistivity lower than the resistivity of the first DBR, the first DBR is an n-type DBR, the second DBR is a p-type DBR, and the light-emitting device is of the back surface emission type.

[0252] (12) The light-emitting device according to (1), further comprising a first electrode provided on the second DBR so as to penetrate the second DBR and in contact with the first semiconductor layer.

[0253] (13) The light-emitting apparatus according to (1), comprising: a lower semiconductor layer provided between the active layer and the first DBR and having a resistivity lower than the resistivity of the first DBR; and an upper semiconductor layer provided between the active layer and the second DBR and having a resistivity lower than the resistivity of the second DBR.

[0254] (14) The light-emitting device according to (13), wherein when the thinner and thicker of the film thickness of the lower semiconductor layer and the upper semiconductor layer are represented by Ta and Tb, respectively, the condition Tb × 1 / 4 < Ta < Tb × 3 / 4 holds true.

[0255] (15) The light-emitting device according to (1), further comprising: a third DBR provided between the first DBR and the active layer; and a fourth DBR provided between the second DBR and the active layer.

[0256] (16) The light-emitting device according to (15), wherein the third DBR or the fourth DBR includes a plurality of alternately stacked first refractive index layers and a plurality of second refractive index layers, and the number of layers of the plurality of first refractive index layers and the number of layers of the plurality of second refractive index layers are both five or less.

[0257] (17) The light-emitting apparatus according to (1), wherein the optical thickness of the first semiconductor layer is an integer multiple of half the oscillation wavelength of the light-emitting element comprising the first DBR, the active layer, the second DBR, and the first semiconductor layer.

[0258] (18) The light-emitting apparatus according to (1), wherein the second DBR is a dielectric DBR.

[0259] (19) The light-emitting device according to (1), further comprising a step-forming layer provided below the second DBR and forming a step.

[0260] (20) A light-emitting device comprising: a substrate; a first DBR provided on the substrate; an active layer provided on the first DBR; a second DBR provided on the active layer; and a first semiconductor layer provided between the active layer and the second DBR and having a thermal conductivity higher than that of the second DBR, or provided between the active layer and the first DBR and having a thermal conductivity lower than that of the first DBR.

[0261] 1: Substrate, 2: Lower DBR, 3: Multilayer film, 3a: Active layer, 3b: Oxide layer, 3b': Non-oxidized layer, 3c: Buffer layer, 3d: Tunnel junction layer, 4: Low-resistance semiconductor layer, 4-1: Lower semiconductor layer, 4-2: Upper semiconductor layer, 5: Upper DBR, 6: Contact layer, 6': Phase adjustment layer, 7: Lower DBR, 8: Upper DBR, 9: Step formation layer, 9a: Part, 11: Upper electrode, 11a: Part, 11b: Part, 12: Passivation film, 13: Anode electrode, 13a: Part, 13b: Part, 14: Cathode electrode, 15: Lower electrode, 16: AR coating film, 20: Vehicle, 20a: Vehicle control system, 21: Vehicle control ECU, 22: Communication unit, 23: Map information storage unit, 24: Location information acquisition unit, 25: External recognition sensor, 26: In-vehicle sensor, 27: Vehicle sensor, 31: Memory unit, 32: Driving assistance / autonomous driving control unit, 33: DMS, 34: HMI, 35: Vehicle control unit, 41: Communication network, 51: Camera, 52: Radar, 53: LiDAR, 54: Ultrasonic sensor, 61: Analysis unit, 62: Action planning unit, 63: Motion control unit, 71: Self-position estimation unit, 72: Sensor fusion unit, 73: Recognition unit, 81: Steering control unit, 82: Brake control unit, 83: Drive control unit, 84: Body system control unit, 85: Light control unit, 86: Horn control unit, 101: Distance measuring device, 102: Light-emitting unit, 102a: Light-emitting element, 103: Drive unit, 104: Power supply circuit, 105: Light-emitting optical system, 106: Light-receiving optical system, 107: Light-receiving unit, 108: Signal processing unit, 109: Control unit, 109a: Distance measuring unit, 110: Temperature detection unit

Claims

circuit board and A first DBR provided on the substrate, The active layer provided on the first DBR, The second DBR provided on the active layer, A first semiconductor layer is provided between the active layer and the second DBR and has a resistivity lower than that of the second DBR, or is provided between the active layer and the first DBR and has a resistivity lower than that of the first DBR. A light-emitting device equipped with the following features. 　 The thickness of the first semiconductor layer is expressed as T [μm], and the OA diameter of the light-emitting element including the first DBR, the active layer, the second DBR, and the first semiconductor layer is D. ＯＡ When expressed in [μm], T > 0.405√D ＯＡ The light-emitting device according to claim 1, wherein -2.55 and T ≥ 1 μm are satisfied. 　 The light-emitting apparatus according to claim 1, wherein the first semiconductor layer is an n-type semiconductor layer. 　 The light-emitting apparatus according to claim 1, wherein the first semiconductor layer is a compound semiconductor layer. 　 The first semiconductor layer is a GaAs layer and / or Al ｘ Ga １－ｘ The light-emitting device according to claim 1, comprising an As layer (where Ga represents gallium, As represents arsenic, Al represents aluminum, and x represents a real number satisfying 0 < x < 0.4). 　 The light-emitting device according to claim 1, further comprising a second semiconductor layer provided between the active layer and the first semiconductor layer. 　 The light-emitting apparatus according to claim 6, wherein the second semiconductor layer is a p-type semiconductor layer. 　 The light-emitting apparatus according to claim 6, further comprising a tunnel junction layer provided between the first semiconductor layer and the second semiconductor layer. 　 The light-emitting apparatus according to claim 8, wherein the tunnel junction layer is in contact with the first semiconductor layer. 　 The first semiconductor layer is provided between the second DBR and the active layer and has a resistivity lower than the resistivity of the second DBR. The light-emitting device according to claim 1, wherein the first DBR is an n-type DBR, the second DBR is an n-type DBR, and the light-emitting device is of the surface emission type. 　 The first semiconductor layer is provided between the first DBR and the active layer and has a resistivity lower than the resistivity of the first DBR. The light-emitting device according to claim 1, wherein the first DBR is an n-type DBR, the second DBR is a p-type DBR, and the light-emitting device is of the back-side emission type. 　 The light-emitting device according to claim 1, further comprising a first electrode provided on the second DBR so as to penetrate the second DBR and in contact with the first semiconductor layer. 　 As the first semiconductor layer, A lower semiconductor layer is provided between the active layer and the first DBR, and has a resistivity lower than that of the first DBR. An upper semiconductor layer is provided between the active layer and the second DBR, and has a resistivity lower than that of the second DBR. The light-emitting device according to claim 1, comprising: 　 The light-emitting device according to claim 13, wherein when the thinner and thicker of the film thickness of the lower semiconductor layer and the upper semiconductor layer are represented by Ta and Tb, respectively, the condition Tb × 1 / 4 < Ta < Tb × 3 / 4 holds true. 　 A third DBR is provided between the first DBR and the active layer, A fourth DBR is provided between the second DBR and the active layer, The light-emitting device according to claim 1, further comprising: 　 The third DBR or the fourth DBR includes a plurality of alternately stacked first refractive index layers and a plurality of second refractive index layers, The light-emitting device according to claim 15, wherein the number of layers of the plurality of first refractive index layers and the number of layers of the plurality of second refractive index layers are both five or less. 　 The light-emitting apparatus according to claim 1, wherein the optical thickness of the first semiconductor layer is an integer multiple of half the oscillation wavelength of the light-emitting element comprising the first DBR, the active layer, the second DBR, and the first semiconductor layer. 　 The light-emitting apparatus according to claim 1, wherein the second DBR is a dielectric DBR. 　 The light-emitting device according to claim 1, further comprising a step-forming layer provided below the second DBR and forming a step. 　 circuit board and A first DBR provided on the substrate, The active layer provided on the first DBR, The second DBR provided on the active layer, A first semiconductor layer is provided between the active layer and the second DBR and has a thermal conductivity higher than that of the second DBR, or is provided between the active layer and the first DBR and has a thermal conductivity lower than that of the first DBR. A light-emitting device equipped with the following features.

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