Light-emitting device and method for manufacturing same

Abstract

[Problem] To provide a light-emitting device capable of suitably performing optical confinement, and a method for manufacturing the same. [Solution] A light-emitting device according to the present disclosure comprises: a substrate; an active layer provided on the substrate; and a step-forming layer that is provided on the active layer and forms a step. The step has, in a cross section perpendicular to the surface of the substrate, a first side on the substrate side and a second side on the opposite side to the substrate. The length of the second side is shorter than the length of the first side. The angle between the first side and a first straight line connecting an end of the first side and an end of the second side is 30 degrees or less.

Description

Light emitting device and method for manufacturing the same

[0001] The present disclosure relates to a light emitting device and a method for manufacturing the same.

[0002] Surface-emitting lasers, such as vertical cavity surface-emitting lasers (VCSELs), are known as one type of semiconductor laser. Generally, in a light-emitting device using a surface-emitting laser, a plurality of light-emitting elements are formed in a two-dimensional array on the front or back surface of a substrate.

[0003] JP-A-2004-289033 JP-A-5-75207

[0004] Light confinement within a VCSEL type light emitting device is achieved by, for example, an oxide confinement structure or a step structure.

[0005] The oxidation confinement structure can confine current in the light-emitting element as well as confine light within the light-emitting element. However, the oxidation confinement structure has problems in that the layer to be oxidized must be exposed by etching, and this etching can damage the light-emitting element.

[0006] On the other hand, the stepped structure can be realized, for example, by a rectangular cross-sectional structure having a rectangular cross section or a curved cross-sectional structure having a curved upper surface. In a rectangular stepped structure, the thickness of the step is set to a predetermined thickness depending on, for example, the wavelength of light or the refractive index of the material. However, the rectangular stepped structure has the problem of deteriorating the characteristics of the light-emitting device, such as an increase in threshold gain due to increased optical loss. In addition, a curved cross-sectional structure achieves optical confinement through the lens effect by shaping the upper surface, for example, in the shape of a convex lens. However, the curved cross-sectional structure has problems such as difficulty in controlling the curved shape of the upper surface, an increase in the cavity length resulting in increased absorption loss, and a narrow transverse mode width (spot size) resulting in reduced internal quantum efficiency.

[0007] Therefore, the present disclosure provides a light emitting device capable of suitably confining light, and a method for manufacturing the same.

[0008] A light-emitting device according to a first aspect of the present disclosure includes a substrate, an active layer disposed on the substrate, and a step-forming layer disposed on the active layer to form a step. The step has, in a cross section perpendicular to the surface of the substrate, a first side on the substrate side and a second side on the opposite side of the substrate, the length of the second side being shorter than the length of the first side, and an angle between the first side and a first line connecting an end of the first side and an end of the second side being 30 degrees or less. This allows for optimal light confinement using the step structure. For example, by making the side surface of the step slope gently, it is possible to suppress light loss, easily control the shape of the top surface, and increase the spot size.

[0009] In addition, in the first side surface, the angle between the first side and the first straight line may be 20 degrees or less. This makes it possible to more suitably perform light confinement by utilizing a step structure, for example.

[0010] In addition, in the first side surface, the angle between the first side and the first straight line may be 10 degrees or less. This makes it possible to more suitably perform light confinement by utilizing a step structure, for example.

[0011] In addition, in the first aspect, the spot size of the light emitted from the light emitting device may be 40% or more of the length of the first side, thereby making it possible to obtain, for example, light with a large spot size.

[0012] Furthermore, the light emitting device of this first aspect may further include a first reflector provided below the active layer on the substrate, and / or a second reflector provided above the active layer on the substrate.

[0013] In addition, in this first aspect, the second reflecting mirror may include a first portion provided below the step and a second portion provided above the step, which makes it possible, for example, to make the second reflecting mirror (first portion) below the step thinner or to increase the reflectance of the entire second reflecting mirror by the second reflecting mirror (second portion) above the step.

[0014] In addition, in the first aspect, the step may further have a third side between the first side and the second side in a cross section perpendicular to the surface of the substrate, and the third side may have a shape with curvature. This makes it possible to easily form the step by utilizing ball-up of a resist layer, for example.

[0015] In addition, in the first side surface, the step may further have a third side between the first side and the second side in a cross section perpendicular to the surface of the substrate, and the third side may have a linear shape, thereby making it possible to form a step having, for example, a simple cross-sectional shape.

[0016] In addition, in this first aspect, the step may have a circular, elliptical, or polygonal shape in a plan view.

[0017] The light emitting device according to the first aspect may further include an underlying layer provided between the active layer and the step forming layer, the underlying layer forming the step.

[0018] In this first aspect, the material of the base forming layer may be the same as the material of the step forming layer, which makes it possible to easily form the step and its base using the same material, for example.

[0019] In the first aspect, the material of the base forming layer may be different from the material of the step forming layer, thereby increasing the degree of freedom in selecting the material of the step, for example.

[0020] In this first aspect, the step-forming layer may include a first layer made of a first material and a second layer made of a second material different from the first material and provided on the first layer, thereby making it possible to form a step having suitable properties by combining a plurality of materials, for example.

[0021] The light emitting device according to the first aspect may further include an oxide confinement layer for current confinement between the substrate and the step, thereby enabling, for example, light confinement to be achieved by the step structure and current confinement to be achieved by the oxide confinement structure.

[0022] The light emitting device of the first aspect may further include a structure for current confinement between the substrate and the step, other than an oxide confinement layer, thereby enabling, for example, light confinement to be achieved by the step structure, and current confinement to be achieved by a structure other than the oxide confinement structure (for example, a high-resistance region formed by ion implantation).

[0023] In addition, in this first aspect, the substrate, the active layer, and the step-forming layer may constitute a plurality of light-emitting elements.

[0024] A light-emitting device according to a second aspect of the present disclosure includes a substrate, an active layer disposed on the substrate, and a step-forming layer disposed on the active layer to form a step. The step, in a cross section perpendicular to the surface of the substrate, has a first side on the substrate side, an upper end portion on the opposite side of the substrate, and a fourth side between the first side and the upper end. The fourth side has a curved or linear shape, and the angle between the first side and a second line connecting the end of the first side and the upper end is 30 degrees or less. This allows for optimal light confinement using the step structure. For example, by making the slope of the step slope gentler, it is possible to reduce light loss, easily control the shape of the slope of the step slope, and increase the spot size.

[0025] In the second aspect, the spot size of the light emitted from the light emitting device may be 40% or more of the length of the first side, thereby making it possible to obtain, for example, light with a large spot size.

[0026] A method for manufacturing a light-emitting device according to a third aspect of the present disclosure includes forming an active layer on a substrate, forming a step-forming layer on the active layer, and forming a step in the step-forming layer, wherein the step is formed to have a first side on the substrate side and a second side on the opposite side of the substrate in a cross section perpendicular to the surface of the substrate, the length of the second side being shorter than the length of the first side, and the angle between the first side and a first line connecting an end of the first side and an end of the second side being set to 30 degrees or less. This enables optimal light confinement using the step structure. For example, by making the side surface of the step slope gently, it is possible to suppress light loss, easily control the shape of the top surface, and increase the spot size.

[0027] In this third aspect, the step in the step-forming layer may be formed by forming a step in a resist layer on the step-forming layer, balling up the step in the resist layer by reflow, etching the step-forming layer using the step in the balled-up resist layer as a mask, and finishing the etching of the step-forming layer before the step in the balled-up resist layer disappears. This makes it possible to easily form the step by utilizing the ball-up of the resist layer, for example.

[0028] 1 is a cross-sectional view showing the structure of a light emitting device of the first embodiment. FIG. 2 is a plan view showing the structure of a light emitting device of the first embodiment. FIG. 3 is an enlarged cross-sectional view showing the structure of a light emitting device of a modified example of the first embodiment. FIG. 4 is a cross-sectional view showing the structure of a light emitting device of a first comparative example of the first embodiment. FIG. 5 is a cross-sectional view showing the structure of a light emitting device of a second comparative example of the first embodiment. FIG. 6 is a graph for explaining the structure of a light emitting device of the first embodiment. FIG. 7 is a cross-sectional view (1 / 5) showing a method for manufacturing a light emitting device of the first embodiment. FIG. 8 is a cross-sectional view (2 / 5) showing a method for manufacturing a light emitting device of the first embodiment. FIG. 9 is a cross-sectional view (3 / 5) showing a method for manufacturing a light emitting device of the first embodiment. FIG. 10 is a cross-sectional view (4 / 5) showing a method for manufacturing a light emitting device of the first embodiment. FIG. 11 is a cross-sectional view (5 / 5) showing a method for manufacturing a light emitting device of the first embodiment. FIG. 12 is a cross-sectional view showing the structure of a light emitting device of the second embodiment. FIG. 13 is a cross-sectional view showing the method for manufacturing a light emitting device of the second embodiment. FIG. 14 is a cross-sectional view showing the structure of a light emitting device of the third embodiment. FIG. 15 is a cross-sectional view showing the structure of a light emitting device of a modified example of the third embodiment. FIG. 16 is a plan view showing three examples of the structure of a light emitting device of the fourth embodiment. FIG. 17 is a cross-sectional view showing the structure of a light emitting device of the fifth embodiment. FIG. 18 is a cross-sectional view showing the structure of a light emitting device of the sixth embodiment. 10. A cross-sectional view showing a manufacturing method of a light emitting device of a sixth embodiment. A cross-sectional view showing the structure of a light emitting device of a seventh embodiment. A cross-sectional view showing the structure of a light emitting device of an eighth embodiment. A cross-sectional view showing the structure of a light emitting device of a ninth embodiment. A cross-sectional view showing two examples of the structure of a light emitting device of a tenth embodiment. A cross-sectional view showing the structure of a light emitting device of an eleventh embodiment. A cross-sectional view showing a manufacturing method of a light emitting device of an eleventh embodiment. A cross-sectional view showing the structure of a light emitting device of a twelfth embodiment. A cross-sectional view showing the structure of a light emitting device of a thirteenth embodiment. A cross-sectional view showing the structure of a light emitting device of a fourteenth embodiment. A cross-sectional view showing the structure of a light emitting device of a modified example of the fourteenth embodiment. A block diagram showing an example of the configuration of a distance measuring device of a fifteenth embodiment. A diagram for explaining the STL system of the fifteenth embodiment. A block diagram showing the configuration of a vehicle of a sixteenth embodiment. A plan view showing the sensing area of ​​a vehicle of a sixteenth embodiment.

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

[0030] 1 and 2 are a cross-sectional view and a plan view, respectively, showing the structure of a light emitting device according to a first embodiment. The light emitting device according to this embodiment is, for example, a surface-emitting VCSEL light emitting device.

[0031] The light emitting device of this embodiment includes a substrate 1, a lower mirror 2, a lower cladding layer 3, an active layer 4, an upper cladding layer 5, an upper mirror 6, an undercoat forming layer 7, a step forming layer 8, an ion implantation region 11, an upper electrode 12, and a lower electrode 13. The lower mirror 2 is an example of a first reflecting mirror of the present disclosure, and the upper mirror 6 is an example of a second reflecting mirror of the present disclosure. The upper mirror 6 includes a mirror 6a and a mirror 6b. The mirror 6a is an example of a first portion of the second reflecting mirror of the present disclosure, and the mirror 6b is an example of a second portion of the second reflecting mirror of the present disclosure.

[0032] 1 and 2 show X, Y, and Z axes that are perpendicular to each other. The X and Y directions correspond to the lateral (horizontal) direction, and the Z direction corresponds to the longitudinal (vertical) direction. The +Z direction corresponds to the upward direction, and the −Z direction corresponds to the downward direction. The −Z direction may or may not strictly coincide with the direction of gravity.

[0033] The structure of the light emitting device of this embodiment will be described in further detail below with reference to Fig. 1. In this description, Fig. 2 will also be referred to as appropriate.

[0034] [Substrate 1] The substrate 1 is, for example, a semiconductor substrate, specifically a compound semiconductor substrate such as a GaAs (gallium arsenide) substrate. Fig. 1 shows a surface (upper surface) Sa of the substrate 1 and a back surface (lower surface) Sb of the substrate 1. In Fig. 1, the surface Sa and back surface Sb of the substrate 1 are parallel to the X direction and the Y direction, and perpendicular to the Z direction.

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

[0036] [Lower Cladding Layer 3 ] The lower cladding layer 3 is formed on the lower mirror 2 and is sandwiched between the lower mirror 2 and the active layer 4 .

[0037] [Active Layer 4] The active layer 4 is formed on the lower cladding layer 3. The active layer 4 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.

[0038] [Upper Cladding Layer 5 ] The upper cladding layer 5 is formed on the active layer 4 and is sandwiched between the active layer 4 and the upper mirror 6 .

[0039] [Upper Mirror 6] The upper mirror 6 includes a mirror 6a formed on the upper cladding layer 5 and a mirror 6b formed on the mirror 6a with an undercoating layer 7 and a step-forming layer 8 interposed therebetween. The mirror 6a is, for example, a DBR formed of a p-type semiconductor layer. The mirror 6a includes a plurality of low-refractive index layers and a plurality of high-refractive index layers alternately stacked on the upper cladding layer 5. The mirror 6b is, for example, a DBR formed of a dielectric layer. The mirror 6b includes a plurality of low-refractive index layers and a plurality of high-refractive index layers alternately stacked on the mirror 6a with the undercoating layer 7 and the step-forming layer 8 interposed therebetween. In this embodiment, the mirror 6b is in contact with the step-forming layer 8 and is also in contact with the undercoating layer 7 around the step-forming layer 8.

[0040] [Base Forming Layer 7, Step Forming Layer 8] The base forming layer 7 is formed on the mirror 6a, and the step forming layer 8 is formed on the base forming layer 7. The step forming layer 8 forms a step having a lower surface S1, an upper surface S2, and a side surface S3. The base forming layer 7 forms a base for this step. The base forming layer 7 and the step forming layer 8 are sandwiched between the mirrors 6a and 6b. As shown in FIG. 1, the step (step forming layer 8) of this embodiment has a convex shape that protrudes in the +Z direction relative to the base forming layer 7. Furthermore, the step (step forming layer 8) of this embodiment has a circular shape in plan view, as indicated by the dashed line in FIG. 2. However, the shape of the step in plan view may be other than circular, as described below. In FIG. 1, the upper surface S2 and the side surface S3 of the step forming layer 8 are covered by the mirror 6b. Note that the step forming layer 8 may have a concave shape recessed toward the base forming layer 7.

[0041] In this embodiment, the base forming layer 7 and the step forming layer 8 are formed of the same material. Specifically, the base forming layer 7 and the step forming layer 8 are formed by forming a step forming layer 9 (see FIG. 8B ) on the mirror 6 b to form the base forming layer 7 and the step forming layer 8, and then processing a portion of the step forming layer 9. In this embodiment, the upper portion of the step forming layer 9 becomes the step forming layer 8, and the lower portion of the step forming layer 9 becomes the base forming layer 7. Therefore, in this embodiment, the interface between the base forming layer 7 and the step forming layer 8 is not observed. Therefore, the lower surface S1 of the step in this embodiment is defined as a cross section passing through the contour line of the lower end of the side surface S3 of the step. The step forming layer 9 is, for example, a semiconductor layer such as a GaAs layer, and is used as a contact layer in contact with the upper electrode 12. In FIG. 1 , the upper electrode 12 is formed on the upper surface of the base forming layer 7. The contact layer is also called a current injection layer.

[0042] In the XZ cross section shown in Figure 1, the step of this embodiment has a side L1 on the substrate 1 side, a side L2 on the opposite side of the substrate 1, and two sides L3 between sides L1 and L2. Side L1 is located on the bottom surface S1, side L2 is located on the top surface S2, and side L3 is located on the side surface S3. Side L1 is an example of a first side in the present disclosure. Side L2 is an example of a second side in the present disclosure. Side L3 is an example of a third side in the present disclosure.

[0043] In FIG. 1, the step of this embodiment has a cross-sectional shape that is close to a trapezoid. Side L1 corresponds to the bottom base (long side) of the trapezoid, and side L2 corresponds to the top base (short side) of the trapezoid. Therefore, the length of side L2 is shorter than the length of side L1. In FIG. 1, both sides L1 and L2 have linear shapes that are parallel to the X direction. On the other hand, in FIG. 1, each side L3 has a shape with curvature, specifically, a shape that protrudes in a direction toward the outside of the step. However, sides L1 to L3 may have shapes different from those shown in FIG. 1. Further details of the shapes of sides L1 to L3 will be described later.

[0044] [Ion Implantation Regions 11] As indicated by dashed lines in Fig. 1 , the ion implantation regions 11 are formed in the lower cladding layer 3, the active layer 4, and the upper cladding layer 5. The ion implantation regions 11 are high-resistance regions formed by ion implantation in the lower cladding layer 3, the active layer 4, and the upper cladding layer 5. This ion implantation is performed using an element capable of increasing resistance, such as B (boron), H (hydrogen), or O (oxygen). Note that in this embodiment, high-resistance regions formed by ion implantation may also exist in the lower mirror 2 and the mirror 6a.

[0045] The ion implantation region 11 has a shape that surrounds the region R in a planar view. The region R has, for example, a circular shape in a planar view. However, the shape of the region R in a planar view may be other than a circle, and may be, for example, an ellipse or a polygon. The ion implantation region 11 of this embodiment is formed to form the ion implantation region 11 that surrounds the region R (light-emitting region) into which carriers are injected, thereby realizing a current confinement structure. The region R of this embodiment functions as a VCSEL-type light-emitting element. The light-emitting element of this embodiment has a non-mesa structure as described above.

[0046] The current confinement may be realized by a structure other than the ion implantation region 11. For example, the current confinement may be realized by a QWI or buried TJ (Tunnel Junction) that confines carriers by creating a band gap energy difference between the aperture portion and the outside thereof through Ga vacancy diffusion. Examples of current confinement structures using a structure other than the ion implantation region 11 will be described later.

[0047] [Upper Electrode 12] The upper electrode 12 is formed on the base forming layer 7 (contact layer). As shown in FIG. 2, the upper electrode 12 has a circular annular shape in plan view, and surrounds the mirror 6b and the step forming layer 8 in a circular shape. The upper electrode 12 is, for example, a metal electrode. The upper electrode 12 is used to inject carriers into the active layer 4. The upper electrode 12 of this embodiment is an anode electrode of the light-emitting element. Note that the shape of the upper electrode 12 in plan view does not have to be a circular annular shape, and may be, for example, a C-shape.

[0048] [Lower Electrode 13] The lower electrode 13 is formed on the rear surface Sb of the substrate 1. The lower electrode 13 is, for example, a metal electrode. The lower electrode 13 is used to inject carriers into the active layer 4. The lower electrode 13 in this embodiment is a cathode electrode of the light-emitting element.

[0049] FIG. 3 is an enlarged cross-sectional view showing the structure of the light emitting device of the first embodiment.

[0050] FIG. 3 shows an enlarged view of the base forming layer 7 and the step forming layer 8 described above. Similar to FIG. 1, FIG. 3 shows sides L1 to L3 in the XZ cross section of the step of this embodiment. FIG. 3 further shows a straight line L3' connecting the end (right end) of side L1 and the end (right end) of side L2 near the right side L3. Since each side L3 of this embodiment has a shape that protrudes toward the outside of the step, the right side L3 protrudes toward the outside of the step relative to the straight line L3'. The straight line L3' is an example of the first straight line of the present disclosure.

[0051] 3 further shows the angle θ between the side L1 and the straight line L3′. The angle θ roughly corresponds to the taper angle of the side surface S3 of the step. In this embodiment, the angle θ is 30 degrees or less (0°<θ≦30°). This allows the taper angle of the side surface S3 of the step to be gentle. The angle θ is preferably 20 degrees or less (0°<θ≦20°), and more preferably 10 degrees or less (0°<θ≦10°).

[0052] According to this embodiment, by forming a step using the step-forming layer 8, it is possible to achieve optical confinement by the step. Furthermore, according to this embodiment, by reducing the step angle θ, it is possible to suppress optical loss in the light-emitting device. This is because, when the step angle θ is large, the change in refractive index along the Z direction becomes steep at the position of the side surface S3 of the step, but by reducing the step angle θ, it is possible to gradually change the refractive index at the side surface S3 of the step. This makes it possible to improve the VCSEL characteristics of the light-emitting device. As such, according to this embodiment, it is possible to preferably achieve optical confinement by utilizing the step structure.

[0053] The above effects can also be obtained by increasing the distance between the active layer 4 and the step and modulating the refractive index, i.e., by setting the step height large. Therefore, according to this embodiment, even if the mirror 6a is placed between the active layer 4 and the step, it is possible to achieve optical confinement while maintaining a low threshold gain.

[0054] In this embodiment, the lower surface S1 and the upper surface S2 of the step are flat, and the side surface S3 of the step is curved. When the upper surface S2 of the step is shaped like a convex lens to achieve light confinement through the lens effect, a problem arises in that the spot size (spot diameter) of the light emitted from the light-emitting element becomes small. According to this embodiment, it is possible to achieve light confinement without using the lens effect, and it is possible to increase the spot size of the light emitted from the light-emitting element. In this embodiment, the spot size of the light emitted from the light-emitting element is, for example, 40% or more of the length of the side L1.

[0055] Furthermore, according to this embodiment, it is possible to easily form a step, for example, as shown in Figures 8 to 12 described below. The reason is that when forming a step having a side surface S3 with a small angle θ, it is easy to control the shape of the side surface S3 of the step. Therefore, according to this embodiment, it is possible to easily mass-produce light-emitting devices.

[0056] In this embodiment, the above relationship holds not only near the right side L3 but also near the left side L3. In this case, the line L3' is a line connecting the left end of the side L1 and the left end of the side L2, and the angle θ is the angle between the side L1 and this line L3'. In FIG. 3, the angle θ near the left side L3 is approximately equal to the angle θ near the right side L3. In other words, the shape of the XZ cross section of the step shown in FIG. 3 is approximately bilaterally symmetrical.

[0057] FIG. 4 is an enlarged cross-sectional view showing the structure of a light emitting device according to a modified example of the first embodiment.

[0058] In Fig. 3, each side L3 has a curved shape. On the other hand, in Fig. 4, each side L3 has a straight line shape. Therefore, the straight line L3' shown in Fig. 4 coincides with the right side L3. Therefore, the angle θ in this modification coincides with the angle between the side L1 and the side L3.

[0059] In this modification, the angle θ is also set to 30 degrees or less (0°<θ≦30°). Furthermore, the angle θ in this modification is also preferably set to 20 degrees or less (0°<θ≦20°), and more preferably set to 10 degrees or less (0°<θ≦10°). This makes it possible to obtain the same effects as in the first embodiment (FIG. 3) in this modification (FIG. 4).

[0060] The step shown in Fig. 3 has a circular lower surface S1 and upper surface S2, and the step shown in Fig. 4 also has a circular lower surface S1 and upper surface S2. However, the step shown in Fig. 3 has a shape obtained by cutting a spherical or nearly spherical three-dimensional figure at the lower surface S1 and upper surface S2, and the step shown in Fig. 4 has a shape obtained by cutting a conical three-dimensional figure at the upper surface S2. Each of Figs. 3 and 4 shows an XZ cross section passing through the circular center of the lower surface S1 and the circular center of the upper surface S2. The step shown in Fig. 3 may have another shape, and the step shown in Fig. 4 may also have another shape.

[0061] FIG. 5 is a cross-sectional view showing the structure of a light emitting device of a first comparative example of the first embodiment.

[0062] The light-emitting device of this comparative example has the same components as the light-emitting device of the first embodiment. However, the steps of this comparative example have a rectangular cross-sectional shape (rectangular step structure) as shown in Figure 5. In the rectangular step structure, the thickness of the steps is set to a predetermined thickness depending on, for example, the wavelength of light or the refractive index of the material. However, the rectangular step structure poses a problem in that the characteristics of the light-emitting element deteriorate, such as an increase in threshold gain due to increased optical loss.

[0063] On the other hand, the step in this embodiment has a cross-sectional shape that is close to a trapezoid (see FIG. 1). According to this embodiment, by reducing the angle θ of the step, it is possible to suppress light loss.

[0064] FIG. 6 is a cross-sectional view showing the structure of a light emitting device of a second comparative example of the first embodiment.

[0065] The light-emitting device of this comparative example has the same components as the light-emitting device of the first embodiment. However, as shown in FIG. 6, the step of this comparative example has a curved upper surface S4 (curved step structure). In the curved cross-sectional structure, the shape of the upper surface S4 is, for example, a convex lens shape, thereby achieving light confinement through the lens effect. However, with the curved cross-sectional structure, problems arise, such as difficulty in controlling the curved shape of the upper surface S4, an increase in the cavity length resulting in increased absorption loss, and a narrow transverse mode width (spot size) resulting in reduced internal quantum efficiency.

[0066] On the other hand, the step in this embodiment has a cross-sectional shape that is close to a trapezoid (see FIG. 1). According to this embodiment, it is possible to achieve light confinement without using the lens effect, and it is possible to increase the spot size of the light emitted from the light-emitting element. Furthermore, according to this embodiment, it is possible to easily form the step by reducing the angle θ of the step.

[0067] The light-emitting device of this comparative example has a mesa structure. Fig. 6 shows a mesa M including a lower mirror 2, a lower cladding layer 3, an active layer 4, an upper cladding layer 5, an upper mirror 6 (mirror 6b), a base forming layer 7, a step forming layer 8, an ion implantation region 11, and an upper electrode 12. The light-emitting device of this comparative example is a back-emission VCSEL light-emitting device, which emits light from the back surface (lower surface) Sb of the substrate 1. The lower electrode 13 of this comparative example is formed on the front surface (upper surface) Sa of the substrate 1 so as to surround the mesa M in a ring shape in a plan view.

[0068] FIG. 7 is a graph for explaining the structure of the light emitting device of the first embodiment.

[0069] The horizontal axis of Fig. 7 represents the angle θ (°) of the step of this embodiment. The vertical axis of Fig. 7 represents the threshold gain gth ( / cm) of the light-emitting element of this embodiment. Fig. 7 shows the calculation results of the relationship between the angle θ and the threshold gain gth.

[0070] 7, it can be seen that the threshold gain gth decreases when the angle θ is 30 degrees or less, and that the threshold gain gth decreases significantly when the angle θ is 10 degrees or less. Therefore, the angle θ in this embodiment is set to 30 degrees or less, preferably 20 degrees or less, and more preferably 10 degrees or less.

[0071] 8 to 12 are cross-sectional views showing a method for manufacturing the light emitting device of the first embodiment.

[0072] [Fig. 8A] First, a substrate 1 is prepared, and a lower mirror 2, a lower cladding layer 3, an active layer 4, and an upper cladding layer 5 are formed in this order on the substrate 1 (Fig. 8A). When forming the lower mirror 2, the lower cladding layer 3, the active layer 4, and the upper cladding layer 5, for example, the lower mirror 2, the lower cladding layer 3, the active layer 4, and the upper cladding layer 5 are epitaxially grown at a growth temperature of 605°C by MOCVD (Metal Organic Chemical Vapor Deposition).

[0073] The quantum well layers and barrier layers in the active layer 4 are formed to contain, for example, Al (aluminum), In (indium), Ga (gallium), and As (arsenic). The Al source gas is, for example, trimethylaluminum ((CH ３ ) ３ The In source gas is, for example, trimethylindium ((CH ３ ) ３ In). The Ga source gas is, for example, trimethylgallium ((CH ３ ) ３ The As source gas is, for example, trimethyl arsenic ((CH ３ ) ３ When MOCVD is performed in the step shown in FIG. 8A, the Si (silicon) source gas is, for example, monosilane (SiH ４ ) is used, and as the C (carbon) source gas, for example, carbon tetrabromide (CBr ４ ) is used, and the Al, In, Ga, and As source gases are, for example, the gases listed above.

[0074] Next, ion implantation regions 11 are formed in the lower cladding layer 3, the active layer 4, and the upper cladding layer 5 by ion implantation ( FIG. 8A ). The ion implantation is performed using an element capable of increasing resistance, such as B (boron), H (hydrogen), or O (oxygen). The deepest part of the ion implantation (the bottom end of the ion implantation region 11) may be located inside any of the upper cladding layer 5, the active layer 4, the lower cladding layer 3, and the lower mirror 2, and in FIG. 8A , it is located near the interface between the lower cladding layer 3 and the lower mirror 2.

[0075] [FIG. 8B] Next, a mirror 6a for forming the upper mirror 6 and a step forming layer 9 for forming the base forming layer 7 and the step forming layer 8 are formed in this order on the upper cladding layer 5 (FIG. 8B). When forming the mirror 6a and the step forming layer 9, for example, the mirror 6a and the step forming layer 9 are epitaxially grown by MOCVD at a growth temperature of 605° C.

[0076] [FIG. 9A] Next, a resist layer 10 is formed on the step-forming layer 9 using photoresist, and the resist layer 10 is patterned by photolithography and etching (FIG. 9A). As a result, a step of the resist layer 10 is formed on the step-forming layer 9. The step of the resist layer 10 is formed to have, for example, a circular shape in a plan view and a rectangular cross section. In this embodiment, the diameters of the lower and upper surfaces of the step of the resist layer 10 are set equal to the diameter (length of side L1) of the lower surface S1 of the step of the step-forming layer 8 shown in FIG.

[0077] [Figure 9B] Next, the step in the resist layer 10 is balled up by heat treatment (reflow) (Figure 9B). As a result, the shape of the step in the resist layer 10 changes to a shape with a flat lower surface and a curved upper surface. The step has a shape, for example, that of a spherical or nearly spherical three-dimensional figure cut at the position of the lower surface.

[0078] [FIGS. 10A and 10B] Next, using the steps of the resist layer 10 as a mask, a portion of the step-forming layer 9 is processed by dry etching (e.g., RIE (Reactive Ion Etching)) (FIG. 10A). This dry etching is completed before the steps of the resist layer 10 disappear and before the mirror 6a is exposed. As shown in FIG. 10A, the upper part of the step-forming layer 9 becomes the step-forming layer 8 including the steps, and the lower part of the step-forming layer 9 becomes the base-forming layer 7 including the base of the steps. FIG. 10A shows the resist layer 10 remaining after the dry etching. This resist layer 10 is removed after the dry etching (FIG. 10B). In FIG. 10B, the steps of the step-forming layer 8 have a lower surface S1 (side L1), an upper surface S2 (side L2), and a side surface S3 (side L3), similar to FIG. 1. In FIGS. 10A and 10B, since both the base forming layer 7 and the step forming layer 8 are obtained from the step forming layer 9, the boundary surface between the base forming layer 7 and the step forming layer 8 is shown by a broken line.

[0079] In this dry etching, the etching selectivity ratio between the resist layer 10 and the step-forming layer 9 is adjusted to approximately 1:1. Therefore, if dry etching is continued until the steps in the resist layer 10 disappear, the shape of the steps in the step-forming layer 8 will be approximately the same as the shape of the steps in the resist layer 10 before the start of dry etching. That is, the shape of the steps in the resist layer 10 is transferred directly to the step-forming layer 8. However, this dry etching is stopped before the steps in the resist layer 10 disappear. Therefore, the shape of the steps in the step-forming layer 8 will be approximately the same as the shape of part of the steps in the resist layer 10 before the start of dry etching. Specifically, the shape of the steps in the step-forming layer 8 will be such that the upper part of the steps in the resist layer 10 before the start of dry etching is cut off. Therefore, the steps in the step-forming layer 8 shown in FIG. 10B have a lower surface S1 (side L1), an upper surface S2 (side L2), and a side surface S3 (side L3), similar to FIG. 1. In FIG. 10B, the lower surface S1 and the upper surface S2 are circular flat surfaces, and the side surface S3 is a curved surface having the same shape as part of the upper surface of the step in the resist layer 10 before the start of dry etching.

[0080] According to this embodiment, by balling up the steps of the resist layer 10, the upper surfaces of the steps of the resist layer 10 can be made into curved inclined surfaces, and the taper angle of the upper surfaces of the steps of the resist layer 10 can be reduced. This makes it possible to reduce the angle θ of the steps of the step-forming layer 8, and to achieve conditions such as "θ≦30°," "θ≦20°," and "θ≦10°."

[0081] [FIG. 11A] Next, a mirror 6b for forming the upper mirror 6 is formed on the base forming layer 7 and the step forming layer 8 (FIG. 11A). The mirror 6b is formed by depositing a plurality of SiO ２ The mirror 6b is formed by alternately stacking a silicon oxide layer and a plurality of silicon (Si) layers. ２ Instead of alternating layers and multiple Si layers, multiple SiO ２ The mirror 6b may include alternating layers of SiO and multiple SiN (silicon nitride) layers. ２ a lower region including alternating layers and multiple SiN layers; and multiple SiO ２ The mirror 6b may have a hybrid configuration with an upper region comprising alternating layers and multiple Si layers. The mirror 6b may be formed by vacuum evaporation, sputtering or CVD, for example.

[0082] [Figure 11B] Next, the mirror 6b is processed by photolithography and dry etching (e.g., RIE) (Figure 11B). As a result, the mirror 6b is processed to have a circular shape in plan view, and the step forming layer 8 is exposed.

[0083] [FIG. 12A] Next, the upper electrode 12 is formed on the step-forming layer 8 (FIG. 12A). The upper electrode 12 is formed by, for example, a lift-off method. The upper electrode 12 is formed to include, for example, a Ti (titanium) layer, a Pt (platinum) layer, and an Au (gold) layer in that order. The metal layer included in the upper electrode 12 is formed by, for example, a vacuum deposition method or a sputtering method.

[0084] [FIG. 12B] Next, a lower electrode 13 is formed on the rear surface Sb of the substrate 1 (FIG. 12B). The lower electrode 13 is formed to include, for example, an AuGe (gold germanium) layer, a Ni (nickel) layer, and an Au (gold) layer in that order. When forming the lower electrode 13, the rear surface Sb of the substrate 1 may be a mirror or rough surface. Before forming the lower electrode 13, the substrate 1 may be thinned by grinding or CMP (Chemical Mechanical Polishing). The metal layer included in the lower electrode 13 is formed by, for example, vacuum deposition or sputtering. In this manner, the light-emitting device of this embodiment is manufactured.

[0085] As described above, the light emitting device of this embodiment has a step formed by the step-forming layer 8, and in a cross section perpendicular to the surface Sa of the substrate 1, this step has a side L1 on the substrate 1 side, a side L2 on the opposite side of the substrate 1, and a side L3 between the sides L1 and L2. Furthermore, in this embodiment, the angle θ between the side L1 and the straight line L3' is set to 30 degrees or less. Therefore, according to this embodiment, it is possible to preferably perform light confinement by utilizing the step structure.

[0086] Second Embodiment FIG. 13 is a cross-sectional view showing the structure of a light emitting device according to a second embodiment.

[0087] The light-emitting device of this embodiment (FIG. 13) includes the same components as the light-emitting device of the first embodiment (FIG. 1). However, in the steps of the step-forming layer 8 of this embodiment, each side L3 has a linear shape rather than a curved shape. In other words, the steps of the step-forming layer 8 of this embodiment have a shape similar to the steps of the step-forming layer 8 of the modified example of the first embodiment (FIG. 4). Therefore, the angle θ of this embodiment is the same as the angle between the side L1 and the side L3.

[0088] In this embodiment, the angle θ is also set to 30 degrees or less. Furthermore, the angle θ in this embodiment is also preferably set to 20 degrees or less, and more preferably set to 10 degrees or less. This makes it possible to obtain the same effects as in the first embodiment (FIG. 1) in this modified example (FIG. 13).

[0089] 14A and 14B are cross-sectional views showing a method for manufacturing a light emitting device according to the second embodiment. In this embodiment, the method for manufacturing a light emitting device according to the first embodiment is performed by replacing the steps shown in FIGS. 9A to 10B with the steps shown in FIGS. 14A to 14B.

[0090] 14A, a resist layer 10 is formed on the step-forming layer 9, and the resist layer 10 is patterned. As a result, a step of the resist layer 10 is formed on the step-forming layer 9. In this embodiment, the step of the resist layer 10 is formed to have, for example, a circular shape in a plan view and a trapezoidal cross section. In this embodiment, the diameter of the lower surface of the step of the resist layer 10 is set equal to the diameter (length of side L1) of the lower surface S1 of the step of the step-forming layer 8 shown in FIG. 13, and the taper angle of the side of the resist layer 10 is set equal to the above-mentioned angle θ. Note that in this embodiment, ball-up of the resist layer 10 is not performed.

[0091] Next, using the steps of the resist layer 10 as a mask, a portion of the step-forming layer 9 is processed by dry etching, and the resist layer 10 remaining after the dry etching is removed ( FIG. 14B ). As a result, as in the first embodiment, a portion of the shape of the steps of the resist layer 10 is transferred to the step-forming layer 8. Therefore, the steps of the step-forming layer 8 shown in FIG. 14B have a lower surface S1 (side L1), an upper surface S2 (side L2), and a side surface S3 (side L3), as in FIG. 13 .

[0092] According to this embodiment, similar to the first embodiment, it is possible to preferably confine light by utilizing the step structure.

[0093] Third Embodiment FIG. 15 is a cross-sectional view showing the structure of a light emitting device according to a third embodiment.

[0094] The light-emitting device of this embodiment (FIG. 15) has the same components as the light-emitting device of the first embodiment (FIG. 1). However, the step of the step-forming layer 8 of this embodiment has a planar lower surface S1 and a curved upper surface S4, and has a cross-sectional shape similar to a portion of an ellipse. The shape of the lower surface S1 is, for example, circular. Furthermore, in the XZ cross section shown in FIG. 15, the step of the step-forming layer 8 of this embodiment has a side L1 on the substrate 1 side, an upper end E on the opposite side of the substrate 1, and two sides L4 between the side L1 and the upper end E. The side L1 is located on the lower surface S1, and each side L4 is located on the upper surface S4. In FIG. 15, the side L1 has a linear shape, and each side L4 has a curved shape. Each side L4 is an example of a fourth side of the present disclosure.

[0095] FIG. 15 further shows a straight line L4' connecting the right end of side L1 and the upper end E near the right side L4. In this embodiment, too, the angle between side L1 and straight line L4' (hereinafter, this angle will also be referred to as "angle θ") is 30 degrees or less. Furthermore, in this embodiment, angle θ is preferably 20 degrees or less, and more preferably 10 degrees or less. This makes it possible to obtain the effects of the first embodiment (FIG. 1) in this embodiment (FIG. 15). Straight line L4' is an example of the second straight line of the present disclosure. In this embodiment, this property holds not only for the right side L4 but also for the left side L4.

[0096] The light emitting device of this embodiment can be manufactured by the method shown in Figures 8A to 12B, for example, in the same way as the light emitting device of the first embodiment. However, when manufacturing the light emitting device of this embodiment, dry etching is continued until the step in the resist layer 10 disappears in the step of Figure 10A.

[0097] The light emitting device of this embodiment is designed so that laser mode formation due to the light focusing effect of the lens does not occur due to the steps in the step forming layer 8. The light emitting device of this embodiment is also designed so that the spot size of the light emitted from the light emitting element is, for example, 40% or more of the length of the side L1. This also applies to modified examples of this embodiment described later.

[0098] FIG. 16 is a cross-sectional view showing the structure of a light emitting device according to a modification of the third embodiment.

[0099] The light-emitting device of this modified example (FIG. 16) has the same components as the light-emitting device of the third embodiment (FIG. 15). However, in the step of the step-forming layer 8 of this modified example, each side L4 has a linear shape rather than a curved shape. Therefore, the step of the step-forming layer 8 of this modified example has a triangular cross-sectional shape. Therefore, the angle θ of this modified example is the same as the angle between the side L1 and the side L4.

[0100] In this modification, the angle θ is also set to 30 degrees or less. Furthermore, the angle θ in this modification is also preferably set to 20 degrees or less, and more preferably set to 10 degrees or less. This makes it possible to obtain the same effects as in the third embodiment (FIG. 15) in this modification (FIG. 16).

[0101] The light emitting device of this modified example can be manufactured, similarly to the light emitting device of the second embodiment, by replacing the steps of Figures 9A to 10B in the manufacturing method of the light emitting device of the first embodiment with the steps of Figures 14A to 14B. However, when manufacturing the light emitting device of this embodiment, in the step of Figure 14A, the step of the resist layer 10 is formed so as to have a triangular vertical cross section, and in the step of Figure 14B, dry etching is continued until the step of the resist layer 10 disappears.

[0102] According to this embodiment, similar to the first and second embodiments, it is possible to preferably confine light by utilizing the step structure.

[0103] Fourth Embodiment FIG. 17 is a plan view showing three examples of the structure of a light emitting device according to a fourth embodiment.

[0104] 17A shows a first example of the planar shape of a step-forming layer 8 (step) provided on an undercoat forming layer 7. In this example, the step has an elliptical shape in a planar view. In FIG. 17A, the undercoat forming layer 7 and the step-forming layer 8 are shown with different hatching to distinguish them from each other (the same applies below).

[0105] 17B shows a second example of the planar shape of the step-forming layer 8 (step) provided on the base forming layer 7. In this example, the step has a quadrangular shape in plan view. In this case, the corners of the quadrangle may be rounded, as shown in FIG.

[0106] 17C shows a third example of the planar shape of the step-forming layer 8 (step) provided on the base forming layer 7. In this example, the step has a hexagonal shape in plan view. In this case, the corners of the hexagon may be rounded as shown in FIG. 17C . The planar shape of the step may also be a polygon other than a hexagon.

[0107] The light emitting device of this embodiment can be manufactured by the method shown in Figures 8A to 12B, for example, as in the light emitting device of the first embodiment. However, when manufacturing the light emitting device of this embodiment, the planar shape of the steps in the resist layer 10 is set to an ellipse, a rectangle, or a hexagon in the step of Figure 9A. Note that the planar shape of the steps in the step forming layer 8 may be a polygon other than a rectangle or a hexagon (for example, a triangle or a pentagon).

[0108] According to this embodiment, similar to the first to third embodiments, it is possible to preferably confine light by utilizing the step structure.

[0109] Fifth Embodiment FIG. 18 is a cross-sectional view showing the structure of a light emitting device according to a fifth embodiment.

[0110] The light-emitting device of this embodiment (FIG. 18) has the same components as the light-emitting device of the first embodiment (FIG. 1). However, as shown in FIG. 18, the light-emitting element of this embodiment has a mesa structure. FIG. 18 shows a mesa M including a lower mirror 2, a lower cladding layer 3, an active layer 4, an upper cladding layer 5, an upper mirror 6 (mirrors 6a and 6b), an undercoat forming layer 7, a step forming layer 8, an ion implantation region 11, an upper electrode 12, and the like. The light-emitting device of this embodiment is a back-emission VCSEL light-emitting device, and emits light from the back surface (lower surface) Sb of the substrate 1.

[0111] The light-emitting device of this embodiment further includes a contact layer 14 provided between the substrate 1 and the lower mirror 2. The lower electrode 13 of this embodiment is formed on the contact layer 14 so as to surround the mesa M in a ring shape in plan view, as shown in FIG.

[0112] The light emitting device of this embodiment can be manufactured by the method shown in FIGS. 8A to 12B, for example, in the same way as the light emitting device of the first embodiment. However, when manufacturing the light emitting device of this embodiment, the contact layer 14 is formed in the step of FIG. 8A, the mesa M is formed in the step of FIG. 12B, and the lower electrode 13 is formed on the contact layer 14 in the step of FIG. 12B. Furthermore, after the step of FIG. 12B, the back surface Sb of the substrate 1 is ground and mirror-finished. In this case, a thin film that does not absorb the oscillation wavelength may be formed as an AR (Anti-Reflection) coating film on the ground and mirror-finished back surface Sb of the substrate 1. The AR coating film may be, for example, SiO ２ The insulating layer may include a SiN layer and / or a SiN layer, and may be formed by a CVD method, a sputtering method, or a vacuum deposition method.

[0113] The lower mirror 2 of this embodiment is formed to include, for example, a plurality of AlGaAs layers and a plurality of GaAs layers alternately. The mirror 6a of this embodiment is formed to include, for example, a plurality of AlGaAs layers and a plurality of GaAs layers alternately. Furthermore, the mirror 6b of this embodiment is formed to include, for example, a plurality of SiO ２ The lower mirror 2, the mirror 6a, and the mirror 6b having such a structure are applicable to the embodiments other than the fifth embodiment.

[0114] According to this embodiment, similar to the first to fourth embodiments, it is possible to preferably confine light by utilizing the step structure.

[0115] Sixth Embodiment FIG. 19 is a cross-sectional view showing the structure of a light emitting device according to a sixth embodiment.

[0116] The light-emitting device of this embodiment (FIG. 19) has the same components as the light-emitting device of the first embodiment (FIG. 1). However, the mirror 6b of this embodiment is a DBR formed of a semiconductor layer instead of a dielectric layer. The upper electrode 12 of this embodiment is formed on the mirror 6b.

[0117] 20A to 20C are cross-sectional views showing a method for manufacturing the light emitting device of the sixth embodiment.

[0118] Fig. 20A shows a cross-sectional view corresponding to Fig. 10B. In this embodiment, the method for manufacturing the light emitting device of the first embodiment is performed by replacing the step of Fig. 11A with the step of Fig. 20B.

[0119] In the step of Fig. 20B, a mirror 6b for forming the upper mirror 6 is formed on the base forming layer 7 and the step forming layer 8. The mirror 6b in this embodiment is formed to include, for example, multiple AlGaAs layers and multiple GaAs layers alternately. The mirror 6b in this embodiment is formed, for example, by the MOCVD method. Note that, in this embodiment, the step of Fig. 11B is not performed. Thereafter, the upper electrode 12 in this embodiment is formed on the mirror 6b as described above.

[0120] According to this embodiment, similar to the first to fifth embodiments, it is possible to preferably confine light by utilizing the step structure.

[0121] Seventh Embodiment FIG. 21 is a cross-sectional view showing the structure of a light emitting device according to a seventh embodiment.

[0122] The light emitting device of this embodiment (FIG. 21) has the same components as the light emitting device of the first embodiment (FIG. 1). However, the upper mirror 6 of this embodiment includes mirror 6b but does not include mirror 6a. The mirror 6b of this embodiment is a DBR formed of a dielectric layer, but it may also be a DBR formed of a semiconductor layer.

[0123] The light emitting device of this embodiment can be manufactured by the method shown in Figures 8A to 12B, for example, in the same manner as the light emitting device of the first embodiment. However, when manufacturing the light emitting device of this embodiment, the process of forming the mirror 6a in the step of Figure 8B is omitted.

[0124] According to this embodiment, similar to the first to sixth embodiments, it is possible to preferably confine light by utilizing the step structure.

[0125] Eighth Embodiment FIG. 22 is a cross-sectional view showing the structure of a light emitting device according to an eighth embodiment.

[0126] The light-emitting device of this embodiment (FIG. 22) has the same components as the light-emitting device of the first embodiment (FIG. 1). However, the upper mirror 6 of this embodiment includes a mirror 6a but does not include a mirror 6b. The mirror 6a of this embodiment is, for example, a DBR formed of a semiconductor layer.

[0127] The light emitting device of this embodiment can be manufactured by the method shown in Figures 8A to 12B, for example, in the same manner as the light emitting device of the first embodiment. However, when manufacturing the light emitting device of this embodiment, the steps of forming and processing the mirror 6b shown in Figures 11A and 11B are omitted.

[0128] According to this embodiment, similar to the first to seventh embodiments, it is possible to preferably confine light by utilizing the step structure.

[0129] Ninth Embodiment FIG. 23 is a cross-sectional view showing the structure of a light emitting device according to a ninth embodiment.

[0130] The light-emitting device of this embodiment (FIG. 22) has the same components as the light-emitting device of the first embodiment (FIG. 1). However, the material of the step-forming layer 8 of this embodiment is different from the material of the base-forming layer 7. The base-forming layer 7 of this embodiment is, for example, a semiconductor layer such as a GaAs layer. The step-forming layer 8 of this embodiment is, for example, an insulating film, but may be a material other than an insulating film.

[0131] The step forming layer 8 of this embodiment is preferably made of a material that is transparent at the oscillation wavelength. When the light emitting element of this embodiment is a GaAs-based VCSEL light emitting element, the step forming layer 8 of this embodiment is made of, for example, SiO ２ layer or SiN layer.

[0132] The light emitting device of this embodiment can be manufactured by the method shown in Figures 8A to 12B, for example, in the same way as the light emitting device of the first embodiment. However, when manufacturing the light emitting device of this embodiment, in the step of Figure 8B, a base forming layer 7 and a step forming layer 8 are formed in this order instead of the step forming layer 9. Furthermore, if the step forming layer 8 is an insulating film, the step forming layer 8 is etched away from the location where the upper electrode 12 is to be formed when or after the step is formed.

[0133] According to this embodiment, similar to the first to eighth embodiments, it is possible to preferably confine light by utilizing the step structure.

[0134] Tenth Embodiment FIG. 24 is a cross-sectional view showing two examples of the structure of a light emitting device according to a tenth embodiment.

[0135] 24A shows a first example of the cross-sectional shape of a step-forming layer 8 (step) provided on an underlayer 7. In this example, the step-forming layer 8 includes a lower layer 8a formed on the underlayer 7 and an upper layer 8b formed on the lower layer 8a, as shown in FIG. 24A . The material of the upper layer 8b in this embodiment is different from the material of the lower layer 8a. The lower layer 8a and the upper layer 8b are examples of the first and second layers of the present disclosure, respectively. The material of the lower layer 8a and the material of the upper layer 8b are examples of the first and second materials of the present disclosure, respectively.

[0136] 24A, the material of the lower layer 8a is the same as the material of the underlayer 7. For example, the lower layer 8a is a semiconductor layer such as a GaAs layer, and the upper layer 8b is a SiO ２ The insulating film is an insulating layer such as a silicon nitride layer or a silicon nitride layer.

[0137] 24B shows a second example of the cross-sectional shape of the step-forming layer 8 (step) provided on the base forming layer 7. In this example, the step-forming layer 8 also includes a lower layer 8 a formed on the base forming layer 7 and an upper layer 8 b formed on the lower layer 8 a, as shown in FIG.

[0138] 24B, the material of the lower layer 8a is different from the material of the base forming layer 7. For example, the lower layer 8a is an insulating film such as a SiO layer, and the upper layer 8b is an insulating film such as a SiN layer. Note that the step forming layer 8 shown in FIG. 24B may further include a part of the base forming layer 7 due to over-etching when processing the step forming layer 8.

[0139] 8A to 12B, the light emitting device of this embodiment can be manufactured by the method shown in Fig. 8A to 12B, for example, in the same manner as the light emitting device of the first embodiment. However, when manufacturing the light emitting device of this embodiment, a lower layer 8a and an upper layer 8b are formed in this order as the step forming layer 8.

[0140] According to this embodiment, similar to the first to ninth embodiments, it is possible to preferably perform optical confinement by utilizing a step structure. The step-forming layer 8 of this embodiment may include three or more layers formed of different materials. Furthermore, N layers (N is an integer of 2 or more) in the step-forming layer 8 of this embodiment may be formed of K types of materials (K is an integer satisfying 1≦K<N). That is, the number of materials forming the step-forming layer 8 may be less than the number of layers forming the step-forming layer 8.

[0141] Eleventh Embodiment FIG. 25 is a cross-sectional view showing the structure of a light emitting device according to an eleventh embodiment.

[0142] The light emitting device of this embodiment (FIG. 25) has the same components as the light emitting device of the first embodiment (FIG. 1). However, the light emitting device of this embodiment has a mesa structure, as shown in FIG. 25. FIG. 25 shows a mesa M including a lower mirror 2, a lower cladding layer 3, an active layer 4, an upper cladding layer 5, an upper mirror 6 (mirrors 6a and 6b), a base forming layer 7, a step forming layer 8, an upper electrode 12, etc.

[0143] The light-emitting device of this embodiment includes an oxide constriction layer 15 instead of the ion-implanted region 11. The oxide constriction layer 15 is formed, for example, in the upper cladding layer 5, and has a shape that surrounds the region R in a plan view. The oxide constriction layer 15 is formed, for example, by oxidizing a part of the AlAs layer provided in the mesa M from the side surface of the mesa M by steam oxidation. According to this embodiment, it is possible to achieve current constriction by using the oxide constriction layer 15 instead of the ion-implanted region 11.

[0144] 26A to 26C are cross-sectional views showing a method for manufacturing the light emitting device of the eleventh embodiment.

[0145] The light emitting device of this embodiment can be manufactured by the method shown in Figures 8A to 12B, for example, as in the light emitting device of the first embodiment. When manufacturing the light emitting device of this embodiment, the mesa M is formed in the step of Figure 12B (see Figure 26A). Furthermore, a portion of the AlAs layer provided in the mesa M is oxidized from the side of the mesa M by steam oxidation to form an oxidized constriction layer 15 in the upper cladding layer 5 (Figure 26B).

[0146] According to this embodiment, it is possible to preferably perform optical confinement by utilizing the step structure, as in the first to tenth embodiments. Note that in this embodiment, the oxidized confinement layer 15 may affect the optical confinement.

[0147] Twelfth Embodiment FIG. 27 is a cross-sectional view showing the structure of a light emitting device according to a twelfth embodiment.

[0148] The light-emitting device of this embodiment (FIG. 27) has the same components as the light-emitting device of the first embodiment (FIG. 1). However, the light-emitting device of this embodiment has an intra-cavity structure, and specifically, the above-mentioned contact layer 14 is provided between a part (mirror 2a) of the lower mirror 2 and the remaining part (mirror 2b) of the lower mirror 2. The contact layer 14 may be provided between the lower mirror 2 and the lower cladding layer 3, or between the lower cladding layer 3 and the active layer 4.

[0149] The light-emitting device of this embodiment has a mesa structure, as shown in FIG. 27 . FIG. 27 shows a mesa M including a mirror 2 b, a lower cladding layer 3, an active layer 4, an upper cladding layer 5, a mirror 6 a, a mirror 6 b, an undercoat forming layer 7, a step forming layer 8, an ion implantation region 11, an upper electrode 12, and the like. The light-emitting device of this embodiment is a back-emission VCSEL light-emitting device, but it may also be a front-emission VCSEL light-emitting device. According to this embodiment, for example, by using a DBR formed of an i-type semiconductor layer as the mirror 2 a, it is possible to reduce the influence of absorption by the lower mirror 2. Furthermore, according to this embodiment, it is possible to reduce the increase in resistance in the lower mirror 2, thereby realizing a reduction in voltage.

[0150] The light emitting device of this embodiment can be manufactured by the method shown in FIGS. 8A to 12B, for example, in the same way as the light emitting device of the first embodiment. However, when manufacturing the light emitting device of this embodiment, in the step of FIG. 8A, a mirror 2a, a contact layer 14, a mirror 2b, a lower cladding layer 3, an active layer 4, and an upper cladding layer 5 are formed in this order on a substrate 1. Furthermore, in the step of FIG. 12B, a mesa M is formed, and in the step of FIG. 12B, a lower electrode 13 is formed on the contact layer 14. Furthermore, after the step of FIG. 12B, the rear surface Sb of the substrate 1 is ground and mirror-finished, and an AR coating film 16 (see FIG. 27) is formed on the ground and mirror-finished rear surface Sb of the substrate 1. The AR coating film 16 can be made of, for example, SiO ２ The insulating layer may include a SiN layer and / or a SiN layer, and may be formed by a CVD method, a sputtering method, or a vacuum deposition method.

[0151] According to this embodiment, similar to the first to eleventh embodiments, it is possible to preferably confine light by utilizing the step structure.

[0152] Thirteenth Embodiment FIG. 28 is a cross-sectional view showing the structure of a light emitting device according to a thirteenth embodiment.

[0153] The light-emitting device of this embodiment ( FIG. 28 ) has the same components as the light-emitting device of the first embodiment ( FIG. 1 ). However, the light-emitting device of this embodiment has a multi-junction structure. Specifically, the active layer 4 includes three partial active layers (a lower active layer 4 a, an intermediate active layer 4 b, and an upper active layer 4 c), a TJ (tunnel junction) layer 17 between the lower active layer 4 a and the intermediate active layer 4 b, and a TJ layer 18 between the intermediate active layer 4 b and the upper active layer 4 c. Note that the number of partial active layers in the active layer 4 and the number of TJ layers in the active layer 4 may be any number. According to this embodiment, current confinement can be achieved by the ion-implanted region 11.

[0154] In this embodiment, the region between the lower active layer 4a and the intermediate active layer 4b includes a p-type semiconductor layer, a TJ layer 17, and an n-type semiconductor layer, which are provided in this order on the lower active layer 4a, and the region between the intermediate active layer 4b and the upper active layer 4c includes a p-type semiconductor layer, a TJ layer 18, and an n-type semiconductor layer, which are provided in this order on the intermediate active layer 4b. Furthermore, the TJ layer 17 includes a highly doped p-type semiconductor layer and a highly doped n-type semiconductor layer, which are provided in this order on the former p-type semiconductor layer. Similarly, the TJ layer 18 includes a highly doped p-type semiconductor layer and a highly doped n-type semiconductor layer, which are provided in this order on the latter p-type semiconductor layer.

[0155] The light emitting device of this embodiment can be manufactured by the method shown in Figures 8A to 12B, for example, in the same manner as the light emitting device of the first embodiment. However, when manufacturing the light emitting device of this embodiment, the above-mentioned multi-junction structure is formed in the step of Figure 8A.

[0156] According to this embodiment, similar to the first to twelfth embodiments, it is possible to preferably confine light by utilizing the step structure.

[0157] Fourteenth Embodiment FIG. 29 is a cross-sectional view showing the structure of a light emitting device according to a fourteenth embodiment.

[0158] The light-emitting device of this embodiment includes a plurality of light-emitting elements P. These light-emitting elements P are arranged, for example, in a two-dimensional array in a planar view. Each light-emitting element P of this embodiment has a structure similar to that of the light-emitting element shown in FIG. 1 (first embodiment). In this embodiment, these light-emitting elements P share the same substrate 1, lower mirror 2, lower cladding layer 3, active layer 4, upper cladding layer 5, and mirror 6a. Similarly, these light-emitting elements P are formed by the same mirror 6b, base forming layer 7, and step forming layer 8, but the mirror 6b, base forming layer 7, and step forming layer 8 are separated for each individual light-emitting element P.

[0159] FIG. 30 is a cross-sectional view showing the structure of a light emitting device according to a modification of the fourteenth embodiment.

[0160] The light-emitting device of this modified example ( FIG. 30 ) has the same components as the light-emitting device of the fourteenth embodiment ( FIG. 29 ). However, the light-emitting device of this modified example further includes an ion-implanted region 19 provided between adjacent light-emitting elements P. In FIG. 30 , the ion-implanted region 19 is formed in the base formation layer 7, the mirror 6 a, and the upper cladding layer 5. The ion-implanted region 19 is formed, for example, by ion implantation into the base formation layer 7, the mirror 6 a, and the upper cladding layer 5. The ion-implanted region 19 of this modified example is provided to prevent current from flowing to the active layer 4 of another light-emitting element P when current is passed through the light-emitting element P to cause the other light-emitting element P to emit light.

[0161] According to this embodiment, similar to the first to thirteenth embodiments, it is possible to preferably confine light by utilizing the step structure.

[0162] In each of the first to fourteenth embodiments, the substrate 1 may be a material other than a GaAs substrate. For example, the substrate 1 may be a GaN substrate or an InP substrate. The structures of the first to fourteenth embodiments are applicable to any material having an oscillation wavelength band of 200 to 2000 nm. In addition, in each of the first to fourteenth embodiments, the step of the step-forming layer 8 has a convex shape, but may instead have a concave shape.

[0163] Fifteenth Embodiment (1) Configuration of Distance Measuring Device 101 Fig. 31 is a block diagram showing an example of the configuration of a distance measuring device 101 according to a fifteenth embodiment. The distance measuring device 101 according to this embodiment is mounted on, for example, an automobile.

[0164] As shown in the figure, the distance measuring device 101 includes an emitter 102, a driver 103, a power supply circuit 104, an emitter optical system 105, a receiver optical system 106, a receiver 107, a signal processor 108, a controller 109, and a temperature detector 110.

[0165] The light-emitting unit 102 emits light from a plurality of light sources. The light-emitting unit 102 in this example has light-emitting elements 102a that are VCSELs (Vertical Cavity Surface Emitting Lasers) as the light sources, and the light-emitting elements 102a are arranged in a predetermined pattern, such as a matrix. The light-emitting unit 102 is, for example, the light-emitting device according to any one of the first to fourteenth embodiments.

[0166] The driving unit 103 includes a power supply circuit for driving the light emitting unit 102 .

[0167] 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 the power supply voltage.

[0168] Light emitted from the light-emitting unit 102 is irradiated onto a subject S, which is the object of distance measurement, via a light-emitting side optical system 105. Then, the light thus irradiated is reflected from the subject S and enters the light-receiving surface of a light-receiving unit 107 via a light-receiving side optical system 106.

[0169] The light receiving unit 107 is a light receiving element such as a CCD (Charge Coupled Device) sensor or a CMOS (Complementary Metal Oxide Semiconductor) sensor, and receives reflected light from the subject S that enters through the light receiving side optical system 106 as described above, converts it into an electrical signal, and outputs it.

[0170] The light receiving unit 107 performs processes such as CDS (Correlated Double Sampling) and AGC (Automatic Gain Control) on the electrical signal obtained by photoelectrically converting the received light, and then performs A / D (Analog / Digital) conversion on the electrical signal, and outputs the resulting digital data to the signal processing unit 108 at the subsequent stage.

[0171] Furthermore, the light receiving unit 107 in this example outputs a frame synchronization signal Fs to the driving unit 103. This enables the driving unit 103 to cause the light emitting element 102a in the light emitting unit 102 to emit light at a timing according to the frame period of the light receiving unit 107.

[0172] The signal processing unit 108 is configured as a signal processor, for example, a DSP (Digital Signal Processor), etc. The signal processing unit 108 performs various signal processes on the digital signal input from the light receiving unit 107.

[0173] The control unit 109 is configured with, for example, a microcomputer having a CPU (Central Processing Unit), ROM (Read Only Memory), RAM (Random Access Memory), etc., or an information processing device such as a DSP, and controls the drive unit 103 to control the light emission operation by the light emitting unit 102, and controls the light receiving operation by the light receiving unit 107.

[0174] The control unit 109 has a function 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). The distance measuring unit 109a in this example measures the distance to each part of the subject S in order to be able to identify the three-dimensional shape of the subject S.

[0175] A specific distance measurement method used by the distance measuring device 101 will be described later.

[0176] The temperature detection unit 110 detects the temperature of the light emitting unit 102. The temperature detection unit 110 may be configured to detect temperature using, for example, a diode.

[0177] In this example, information about the temperature 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.

[0178] (2) Distance Measurement Method The distance measurement method used in the distance measuring device 101 may be, for example, a structured light (STL) method or a time of flight (ToF) method.

[0179] The STL method is a method for measuring distance based on an image of a subject S illuminated with light having a predetermined light / dark pattern, such as a dot pattern or a grid pattern.

[0180] FIG. 32 is a diagram for explaining the STL system of the fifteenth embodiment.

[0181] In the STL method, pattern light Lp having a dot pattern such as that shown in Fig. 32A is irradiated onto the subject S. The pattern light Lp is divided into a plurality of blocks BL, and a different dot pattern is assigned to each block BL (dot patterns are arranged not to overlap between blocks BL).

[0182] FIG. 32B is an explanatory diagram of the distance measurement principle of the STL system.

[0183] In this example, a wall W and a box BX placed in front of it are treated as the subject S, and pattern light Lp is irradiated onto the subject S. "G" in the figure schematically represents the angle of view of the light receiving unit 107.

[0184] In addition, in the drawing, "BLn" denotes the light of a certain block BL in the pattern light Lp, and "dn" denotes the dot pattern of the block BLn projected on the light-receiving image by the light-receiving unit 107.

[0185] Here, if there is no box BX in front of the wall W, the dot pattern of the block BLn is projected at the position "dn'" in the figure in the received light image. In other words, the position at which the pattern of the block BLn is projected in the received light image differs depending on whether the box BX is present or not, and specifically, the pattern is distorted.

[0186] The STL method utilizes the fact that the irradiated pattern is distorted by the object shape of the subject S to determine the shape and depth of the subject S. Specifically, this method determines the shape and depth of the subject S from the way the pattern is distorted.

[0187] When the STL system is adopted, for example, a global shutter type IR (Infrared) light receiving unit is used as the light receiving unit 107. In the case of the STL system, the distance measuring unit 109a controls the drive unit 103 so that the light emitting unit 102 emits pattern light, detects distortion of the pattern in the image signal obtained via the signal processing unit 108, and calculates the distance based on the distortion of the pattern.

[0188] Next, the ToF method is a method for measuring the distance to an object by detecting the time of flight (time difference) of light emitted from the light-emitting unit 102, reflected by the object, and reaching the light-receiving unit 107.

[0189] When a 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 between light emission and reception of light emitted from the light emitting unit 102 and received by the light receiving unit 107, based on a signal input via the signal processing unit 108, and calculates the distance to each part of the subject S based on the time difference and the speed of light.

[0190] When a so-called indirect ToF (iToF) method (phase difference method) is adopted as the ToF method, a light receiving unit capable of receiving, for example, IR light is used as the light receiving unit 107 .

[0191] Although the light emitting devices of the first to fourteenth embodiments are used as light sources for the distance measuring device 101 in the fifteenth embodiment, they may also be used in other ways. For example, the light emitting devices of these embodiments may be used as light sources for optical devices such as printers, or as lighting devices.

[0192] Sixteenth Embodiment Fig. 33 is a block diagram showing the configuration of a vehicle 20 according to a sixteenth embodiment. Fig. 33 shows an example of the configuration of a vehicle control system 20a, which is an example of a mobility device control system.

[0193] The vehicle control system 20 a is provided in the vehicle 20 and performs processing related to driving assistance and automatic driving of the vehicle 20 .

[0194] 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 position information acquisition unit 24, an external recognition sensor 25, an in-vehicle sensor 26, a vehicle sensor 27, a memory unit 31, a driving assistance / 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 fifteenth embodiment.

[0195] The vehicle control ECU 21, communication unit 22, map information storage unit 23, position information acquisition unit 24, external recognition sensor 25, in-vehicle sensor 26, vehicle sensor 27, memory unit 31, cruise assist / autonomous driving control unit 32, driver monitoring system (DMS) 33, human-machine interface (HMI) 34, and vehicle control unit 35 are interconnected via a communication network 41 for mutual communication. The communication network 41 is configured, for example, by an in-vehicle communication network or bus conforming to a digital bidirectional communication standard such as a Controller Area Network (CAN), a Local Interconnect Network (LIN), a Local Area Network (LAN), FlexRay (registered trademark), or Ethernet (registered trademark). Different communication networks 41 may be used depending on the type of data being transmitted. For example, a CAN may be used for data related to vehicle control, and an Ethernet may be used for large-volume data. In addition, each part of the vehicle control system 20a may be directly connected without going through the communication network 41, using wireless communication intended for communication over relatively short distances, such as near field communication (NFC) or Bluetooth (registered trademark).

[0196] In the following description, when each unit 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 that the vehicle control ECU 21 and the communication unit 22 communicate with each other.

[0197] [Vehicle Control ECU 21] The vehicle control ECU 21 is configured by various processors such as a CPU (Central Processing Unit), an MPU (Micro Processing Unit), etc. The vehicle control ECU 21 controls all or part of the functions of the vehicle control system 20a.

[0198] [Communication Unit 22] The communication unit 22 communicates with various devices inside and outside the vehicle, other vehicles, servers, base stations, etc., and transmits and receives various data. At this time, the communication unit 22 can communicate using multiple communication methods.

[0199] The following provides an overview of communication with the outside of the vehicle that can be performed by the communication unit 22. The communication unit 22 communicates with a server (hereinafter referred to as an external server) or the like on an external network via a base station or an access point using a wireless communication method such as 5G (fifth generation mobile communication system), LTE (Long Term Evolution), or 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 with the external network is not particularly limited as long as it is a wireless communication method that enables digital two-way communication at a communication speed equal to or higher than a predetermined distance.

[0200] Furthermore, for example, the communication unit 22 can communicate with a terminal located near the vehicle using P2P (Peer to Peer) technology. The terminal located near the vehicle can be, for example, a terminal worn by a mobile object moving at a relatively slow speed, such as a pedestrian or a bicycle, a terminal installed at a fixed location in a store, or an MTC (Machine Type Communication) terminal. Furthermore, the communication unit 22 can also perform V2X communication. V2X communication refers to communication between the vehicle and others, such as vehicle-to-vehicle communication with another vehicle, vehicle-to-infrastructure communication with a roadside unit, vehicle-to-home communication, and vehicle-to-pedestrian communication with a terminal carried by a pedestrian.

[0201] The communication unit 22 can receive, for example, a program for updating software that controls the operation of the vehicle control system 20a from the outside (over the air). The communication unit 22 can also receive map information, traffic information, information about the surroundings of the vehicle 20, and the like from the outside. For example, the communication unit 22 can also transmit information about the vehicle 20 and the surroundings of the vehicle 20 to the outside. Information about the vehicle 20 that the communication unit 22 transmits to the outside includes, for example, data indicating the status of the vehicle 20 and the recognition result by the recognition unit 73. Furthermore, for example, the communication unit 22 performs communication corresponding to a vehicle emergency notification system such as e-call.

[0202] For example, the communication unit 22 receives electromagnetic waves transmitted by a road traffic information and communication system (VICS (Vehicle Information and Communication System) (registered trademark)) such as a radio beacon, an optical beacon, or FM multiplex broadcasting.

[0203] The following provides an overview of communication with the vehicle interior that can be performed by the communication unit 22. The communication unit 22 can communicate with each device in the vehicle using, for example, wireless communication. The communication unit 22 can communicate with each device in the vehicle using a communication method that enables bidirectional digital communication at a predetermined communication speed or higher via wireless communication, such as wireless LAN, Bluetooth, NFC, or Wireless USB (WUSB). The communication unit 22 can also communicate with each device in the vehicle using wired communication. For example, the communication unit 22 can communicate with each device in the vehicle using wired communication via a cable connected to a connection terminal (not shown). The communication unit 22 can communicate with each device in the vehicle using a communication method that enables bidirectional digital communication at a predetermined communication speed or higher via wired communication, such as Universal Serial Bus (USB), High-Definition Multimedia Interface (HDMI) (registered trademark), or Mobile High-Definition Link (MHL).

[0204] Here, the in-vehicle device refers to, for example, a device in the vehicle that is not connected to the communication network 41. Possible in-vehicle devices include, for example, a mobile device or wearable device carried by a passenger such as a driver, and an information device brought into the vehicle and temporarily installed therein.

[0205] [Map Information Storage Unit 23] The map information storage unit 23 stores one or both of a map acquired from an external source and a map created by the vehicle 20. For example, the map information storage unit 23 stores a three-dimensional high-precision map, a global map that is less accurate than a high-precision map and covers a wide area, and the like.

[0206] Examples of high-precision maps include dynamic maps, point cloud maps, and vector maps. A dynamic map is a map consisting of four layers of dynamic information, quasi-dynamic information, quasi-static information, and static information, and is provided to the vehicle 20 from an external server or the like. A point cloud map is a map made up of a point cloud (point group data). A vector map is a map that corresponds traffic information such as the positions of lanes and traffic lights to the point cloud map and is adapted to an advanced driver assistance system (ADAS) or autonomous driving (AD).

[0207] The point cloud map and the vector map may be provided, for example, from an external server or the like, or may be created in the vehicle 20 based on sensing results from the camera 51, radar 52, LiDAR 53, etc. as a map for matching with a local map described later, and stored in the map information storage unit 23. Furthermore, when a high-precision map is provided from an external server or the like, map data of, for example, an area of ​​several hundred square meters relating to the planned route along which the vehicle 20 will travel is acquired from the external server or the like in order to reduce communication capacity.

[0208] [Location Information Acquisition Unit 24] The location information acquisition unit 24 receives GNSS (Global Navigation Satellite System) signals from satellites and acquires location information of the vehicle 20. The acquired location information is supplied to the driving assistance / autonomous driving control unit 32. Note that the location information acquisition unit 24 is not limited to a method using GNSS signals, and may acquire location information using a beacon, for example.

[0209] [External Recognition Sensor 25] The external recognition sensor 25 includes various sensors used to recognize the situation outside the vehicle 20, and supplies sensor data from each sensor to each part of the vehicle control system 20a. The type and number of sensors included in the external recognition sensor 25 are arbitrary.

[0210] 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. Without being limited to this, the external recognition sensor 25 may be configured to include one or more types of sensors selected from the camera 51, the radar 52, the LiDAR 53, and the ultrasonic sensor 54. The number of cameras 51, radars 52, LiDARs 53, and ultrasonic sensors 54 is not particularly limited as long as the number 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 sensing areas of each sensor included in the external recognition sensor 25 will be described later.

[0211] The imaging method of the camera 51 is not particularly limited. For example, cameras of various imaging methods capable of distance measurement, such as a time-of-flight (ToF) camera, a stereo camera, a monocular camera, and an infrared camera, can be applied to the camera 51 as needed. However, the camera 51 may simply acquire an image without distance measurement.

[0212] Furthermore, for example, the external recognition sensor 25 may include an environmental sensor for detecting the environment of the vehicle 20. The environmental sensor is a sensor for detecting the environment such as weather, climate, brightness, etc., and may include various sensors such as a raindrop sensor, a fog sensor, a sunlight sensor, a snow sensor, and an illuminance sensor.

[0213] Furthermore, for example, the external recognition sensor 25 includes a microphone used to detect sounds around the vehicle 20 and the location of sound sources.

[0214] [In-vehicle sensor 26] The in-vehicle sensor 26 includes various sensors for detecting information inside the vehicle, and supplies sensor data from each sensor to each component of the vehicle control system 20 a. The types and number of the various sensors included in the in-vehicle sensor 26 are not particularly limited as long as they are of types and numbers that can be realistically installed in the vehicle 20.

[0215] For example, the interior sensor 26 may include one or more types of sensors selected from the group consisting of a camera, radar, a seating sensor, a steering wheel sensor, a microphone, and a biometric sensor. The camera included in the interior sensor 26 may be a camera using any of various imaging methods capable of measuring distances, such as a Time of Flight (ToF) camera, a stereo camera, a monocular camera, or an infrared camera. The camera included in the interior sensor 26 may also be a camera simply for acquiring captured images, regardless of distance measurement. The biometric sensor included in the interior sensor 26 may be provided, for example, on a seat, a steering wheel, or the like, and detect various types of biometric information of a passenger, such as a driver.

[0216] [Vehicle Sensor 27] The vehicle sensor 27 includes various sensors for detecting the state of the vehicle 20, and supplies sensor data from each sensor to each unit of the vehicle control system 20a. The types and number of the various sensors included in the vehicle sensor 27 are not particularly limited as long as they are of types and numbers that can be realistically installed on the vehicle 20.

[0217] 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 these sensors. For example, the vehicle sensor 27 includes a steering angle sensor that detects the steering angle of the steering wheel, a yaw rate sensor, an accelerator sensor that detects the amount of accelerator pedal operation, and a brake sensor that detects the amount of brake pedal operation. For example, the vehicle sensor 27 includes a rotation sensor that detects the number of rotations of the engine or motor, an air pressure sensor that detects tire air pressure, a slip ratio sensor that detects tire slip ratio, and a wheel speed sensor that detects the rotation speed of the wheels. For example, the vehicle sensor 27 includes a battery sensor that detects the remaining battery charge and temperature, and an impact sensor that detects external impacts.

[0218] [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, for example, as an electrically erasable programmable read-only memory (EEPROM) and a random access memory (RAM). Examples of storage media that can be used include magnetic storage devices such as hard disk drives (HDDs), semiconductor storage devices, optical storage devices, and magneto-optical storage devices. The storage unit 31 stores various programs and data used by each component of the vehicle control system 20a. For example, the storage unit 31 includes an event data recorder (EDR) and a data storage system for automated driving (DSSAD), and stores information about the vehicle 20 before and after an event such as an accident, as well as information acquired by the in-vehicle sensors 26.

[0219] [Driving assistance / automatic driving control unit 32] The driving assistance / automatic driving control unit 32 controls 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.

[0220] The analysis unit 61 performs an analysis process of the vehicle 20 and the surrounding situation. The analysis unit 61 includes a self-position estimation unit 71, a sensor fusion unit 72, and a recognition unit 73.

[0221] The self-position estimation unit 71 estimates the self-position of the vehicle 20 based on the sensor data from the external recognition sensor 25 and the 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 matches the local map with the high-precision map to estimate the self-position of the vehicle 20. The position of the vehicle 20 is based on, for example, the center of the rear wheel pair axle.

[0222] The local map is, for example, a three-dimensional high-precision map or an occupancy grid map created using a technology such as SLAM (Simultaneous Localization and Mapping). The three-dimensional high-precision map is, for example, the point cloud map described above. The occupancy grid map is a map in which the three-dimensional or two-dimensional space around the vehicle 20 is divided into grids of a predetermined size and the occupancy status of objects is indicated on a grid-by-grid basis. The occupancy status of objects is indicated, for example, by the presence or absence of an object and its probability of existence. The local map is also used, for example, in the detection process and recognition process of the situation outside the vehicle 20 by the recognition unit 73.

[0223] The self-position estimation unit 71 may estimate the self-position of the vehicle 20 based on the position information acquired by the position information acquisition unit 24 and the sensor data from the vehicle sensor 27 .

[0224] 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 association.

[0225] The recognition unit 73 executes a detection process for detecting the situation outside the vehicle 20 and a recognition process for recognizing the situation outside the vehicle 20 .

[0226] For example, the recognition unit 73 performs detection processing and recognition processing of the situation outside 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, and the like.

[0227] Specifically, for example, the recognition unit 73 performs detection processing and recognition processing of objects around the vehicle 20. The object detection processing is, for example, processing to detect the presence or absence, size, shape, position, movement, etc. of an object. The object recognition processing is, for example, processing to recognize attributes such as the type of object, or to identify a specific object. However, the detection processing and the recognition processing are not necessarily clearly separated, and may overlap.

[0228] For example, the recognition unit 73 detects objects around the vehicle 20 by performing clustering to classify a point cloud based on sensor data from the radar 52, the LiDAR 53, or the like into clusters of points. This allows the presence, size, shape, and position of objects around the vehicle 20 to be detected.

[0229] For example, the recognition unit 73 performs tracking to follow the movement of clusters of point clouds classified by clustering, thereby detecting the movement of objects around the vehicle 20. As a result, the speed and traveling direction (movement vector) of the objects around the vehicle 20 are detected.

[0230] 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.

[0231] 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 estimation result of the self-position by the self-position estimation unit 71, and the recognition result of the objects around the vehicle 20 by the recognition unit 73. Through this processing, the recognition unit 73 can recognize the positions and states of traffic lights, the contents of traffic signs and road markings, the contents of traffic regulations, and lanes that can be traveled, etc.

[0232] For example, the recognition unit 73 can perform a recognition process of the environment around the vehicle 20. The surrounding environment that the recognition unit 73 recognizes may include the weather, temperature, humidity, brightness, and road surface conditions.

[0233] The behavior planning unit 62 creates a behavior plan for the vehicle 20. For example, the behavior planning unit 62 creates the behavior plan by performing route planning and route tracking processing.

[0234] Global path planning is a process for planning a rough route from the start to the goal. This route planning also includes a process for generating a trajectory (local path planning) that takes into account the motion characteristics of the vehicle 20 on the planned route and enables safe and smooth travel in the vicinity of the vehicle 20.

[0235] Path following is a process of planning an operation for safely and accurately traveling along a route planned by a route plan within a planned time. The behavior planning unit 62 can, for example, calculate a target speed and a target angular velocity of the vehicle 20 based on the results of this path following process.

[0236] The operation control unit 63 controls the operation of the vehicle 20 in order to realize the action plan created by the action planning unit 62 .

[0237] For example, the operation control unit 63 controls the steering control unit 81, the brake control unit 82, and the drive control unit 83 included in the vehicle control unit 35 described later to perform acceleration / deceleration control and direction control so that the vehicle 20 travels along the trajectory calculated by the trajectory plan. For example, the operation control unit 63 performs cooperative control with the aim of realizing ADAS functions such as collision avoidance or impact mitigation, following driving, vehicle speed maintenance driving, collision warning for the host vehicle, and lane departure warning for the host vehicle. For example, the operation control unit 63 performs cooperative control with the aim of automatic driving, which drives autonomously without driver operation.

[0238] [DMS 33] The DMS 33 performs processes such as authenticating the driver and recognizing the driver's state based on sensor data from the in-vehicle sensors 26 and input data input to the HMI 34 (described later). Examples of the driver's state to be recognized include physical condition, alertness, concentration, fatigue, line of sight, level of intoxication, driving operation, and posture.

[0239] The DMS 33 may be configured to perform authentication processing for passengers other than the driver and recognition processing for the conditions of the passengers. Furthermore, for example, the DMS 33 may be configured to perform recognition processing for the conditions inside the vehicle based on sensor data from the in-vehicle sensor 26. Possible conditions inside the vehicle to be recognized include, for example, temperature, humidity, brightness, and odor.

[0240] [HMI 34] The HMI 34 receives input of various data and instructions, and presents various data to the driver and the like.

[0241] The following provides an overview of data input via the HMI 34. The HMI 34 includes input devices for a person to input data. The HMI 34 generates input signals based on data, instructions, and the like input via the input devices and supplies the signals to each component of the vehicle control system 20a. The HMI 34 includes input devices such as a touch panel, buttons, switches, and levers. The HMI 34 may also include input devices that allow information to be input by voice, gestures, or other means other than manual operation. Furthermore, the HMI 34 may use, as input devices, externally connected devices such as a remote control device using infrared or radio waves, or a mobile or wearable device compatible with the operation of the vehicle control system 20a.

[0242] The presentation of data by the HMI 34 will be briefly described. The HMI 34 generates visual information, auditory information, and tactile information for the occupant or the outside of the vehicle. The HMI 34 also performs output control, controlling the output, output content, output timing, output method, etc. of each piece of generated information. The HMI 34 generates and outputs, as visual information, information indicated by images or lights, such as an operation screen, a status display of the vehicle 20, a warning display, and a monitor image showing the situation around the vehicle 20. The HMI 34 also generates and outputs, as auditory information, information indicated by sounds, such as voice guidance, warning sounds, and warning messages. The HMI 34 also generates and outputs, as tactile information, information imparted to the occupant's sense of touch by, for example, force, vibration, movement, etc.

[0243] Examples of output devices that the HMI 34 uses to output visual information include a display device that displays an image on its own to present visual information and a projector device that projects an image to present visual information. The display device may be a device that displays visual information within the occupant's field of view, such as a head-up display, a transmissive display, or a wearable device with an augmented reality (AR) function, in addition to a display device having a normal display. The HMI 34 may also use display devices included in a navigation system, an instrument panel, a camera monitoring system (CMS), an electronic mirror, a lamp, or the like provided in the vehicle 20 as output devices that output visual information.

[0244] As an output device for the HMI 34 to output auditory information, for example, an audio speaker, a headphone, or an earphone can be applied.

[0245] For example, a haptic element using haptic technology can be applied as an output device for outputting tactile information from the HMI 34. The haptic element is provided on a part of the vehicle 20 that an occupant comes into contact with, such as a steering wheel or a seat.

[0246] [Vehicle Control Unit 35] The vehicle control unit 35 controls each unit 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.

[0247] 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 including a steering wheel, an electric power steering, 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.

[0248] 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 antilock brake system (ABS), a regenerative brake 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.

[0249] The drive control unit 83 detects and controls the state of the drive system of the vehicle 20. The drive system includes, for example, an accelerator pedal, a drive force generating device for generating drive force such as an internal combustion engine or a drive motor, and a drive force transmission mechanism for transmitting the drive force to the wheels. The drive control unit 83 includes, for example, a drive ECU for controlling the drive system, and an actuator for driving the drive system.

[0250] The body system control unit 84 detects and controls the states of the body system systems of the vehicle 20. The body system systems include, for example, a keyless entry system, a smart key system, a power window device, a power seat, an air conditioning system, an airbag, a seat belt, a shift lever, etc. The body system control unit 84 includes, for example, a body system ECU that controls the body system systems, an actuator that drives the body system systems, etc.

[0251] The light control unit 85 detects and controls the states of various lights of the vehicle 20. Examples of lights to be controlled include headlights, backlights, fog lights, turn signals, brake lights, projections, and bumper displays. The light control unit 85 includes a light ECU that controls the lights, an actuator that drives the lights, and the like.

[0252] The horn control unit 86 detects and controls the state of the car horn of the vehicle 20. The horn control unit 86 includes, for example, a horn ECU that controls the car horn, an actuator that drives the car horn, and the like.

[0253] Fig. 34 is a plan view showing the sensing area of ​​the vehicle 20 of the sixteenth embodiment. Fig. 34 shows an example of the sensing area of ​​the camera 51, radar 52, LiDAR 53, ultrasonic sensor 54, etc. of the external recognition sensor 25 of Fig. 33. Note that Fig. 34 schematically shows the vehicle 20 as seen from above, with the left end side being the front end (front) side of the vehicle 20 and the right end side being the rear end (rear) side of the vehicle 20.

[0254] [Sensing Areas 1-1F, 1-1B] Sensing area 1-1F and sensing area 1-1B are examples of sensing areas of the ultrasonic sensors 54. Sensing area 1-1F covers the periphery of the front end of the vehicle 20 with multiple ultrasonic sensors 54. Sensing area 1-1B covers the periphery of the rear end of the vehicle 20 with multiple ultrasonic sensors 54.

[0255] The sensing results in the sensing area 1-1F and the sensing area 1-1B are used, for example, for parking assistance for the vehicle 20.

[0256] [Sensing Areas 1-2F, B, L, R] Sensing area 1-2F to sensing area 1-2B show examples of sensing areas of a short-range or medium-range radar 52. Sensing area 1-2F covers a position farther in front of the vehicle 20 than sensing area 1-1F. Sensing area 1-2B covers a position farther behind the vehicle 20 than sensing area 1-1B. Sensing area 1-2L covers the periphery behind the left side of the vehicle 20. Sensing area 1-2R covers the periphery behind the right side of the vehicle 20.

[0257] The sensing results in sensing area 1-2F are used, for example, to detect vehicles, pedestrians, and the like that are present in front of the vehicle 20. The sensing results in sensing area 1-2B are used, for example, for collision prevention functions behind the vehicle 20. The sensing results in sensing area 1-2L and sensing area 1-2R are used, for example, to detect objects in blind spots on the sides of the vehicle 20.

[0258] [Sensing Areas 1-3F, B, L, R] Sensing area 1-3F to sensing area 1-3B show examples of sensing areas sensed by camera 51. Sensing area 1-3F covers a position farther in front of vehicle 20 than sensing area 1-2F. Sensing area 1-3B covers a position farther in rear of vehicle 20 than sensing area 1-2B. Sensing area 1-3L covers the periphery of the left side of vehicle 20. Sensing area 1-3R covers the periphery of the right side of vehicle 20.

[0259] The sensing results in sensing area 1-3F can be used, for example, for recognizing traffic lights and traffic signs, lane departure prevention assistance systems, and automatic headlight control systems. The sensing results in sensing area 1-3B can be used, for example, for parking assistance and surround view systems. The sensing results in sensing area 1-3L and sensing area 1-3R can be used, for example, for surround view systems.

[0260] [Sensing area 1-4] Sensing area 1-4 shows an example of the sensing area of ​​the LiDAR 53. Sensing area 1-4 covers a position farther ahead of the vehicle 20 than sensing area 1-3F. On the other hand, sensing area 1-4 has a narrower range in the left-right direction than sensing area 1-3F.

[0261] The sensing results in the sensing areas 1-4 are used to detect objects such as surrounding vehicles, for example.

[0262] [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 ahead 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.

[0263] The sensing results in the sensing areas 1-5 are used for, for example, adaptive cruise control (ACC), emergency braking, collision avoidance, and the like.

[0264] The sensing areas of the cameras 51, radars 52, LiDARs 53, and ultrasonic sensors 54 included in the external recognition sensor 25 may have various configurations other than those shown in FIG. 34 . Specifically, the ultrasonic sensors 54 may also sense the sides of the vehicle 20, and the LiDAR 53 may sense the rear of the vehicle 20. The installation positions of the sensors are not limited to the above-described examples. The number of each sensor may be one or more.

[0265] Although the embodiments of the present disclosure have been described above, these embodiments may be implemented with various modifications within the scope of the gist of the present disclosure. For example, two or more embodiments may be implemented in combination.

[0266] The present disclosure may also be configured as follows.

[0267] (1) A light-emitting device comprising: a substrate; an active layer provided on the substrate; and a step-forming layer provided on the active layer and forming a step, wherein the step has, in a cross section perpendicular to a surface of the substrate, a first side on the substrate side and a second side on the opposite side of the substrate, the length of the second side being shorter than the length of the first side, and the angle between the first side and a first line connecting an end of the first side and an end of the second side being 30 degrees or less.

[0268] (2) The light emitting device according to (1), wherein the angle between the first side and the first straight line is 20 degrees or less.

[0269] (3) The light emitting device according to (1), wherein the angle between the first side and the first straight line is 10 degrees or less.

[0270] (4) The light emitting device according to (1), wherein the spot size of the light emitted from the light emitting device is 40% or more of the length of the first side.

[0271] (5) The light emitting device according to (1), further comprising: a first reflector provided below the active layer on the substrate; and / or a second reflector provided above the active layer on the substrate.

[0272] (6) The light emitting device according to (5), wherein the second reflecting mirror includes a first portion provided below the step and a second portion provided above the step.

[0273] (7) The light-emitting device according to (1), wherein the step further has a third side between the first side and the second side in a cross section perpendicular to the surface of the substrate, and the third side has a shape with curvature.

[0274] (8) The light-emitting device according to (1), wherein the step further has a third side between the first side and the second side in a cross section perpendicular to the surface of the substrate, and the third side has a linear shape.

[0275] (9) The light emitting device according to (1), wherein the step has a circular, elliptical, or polygonal shape in plan view.

[0276] (10) The light-emitting device according to (1), further comprising an undercoat forming layer provided between the active layer and the step forming layer to form an undercoat of the step.

[0277] (11) The light-emitting device according to (10), wherein the material of the base forming layer is the same as the material of the step forming layer.

[0278] (12) The light-emitting device according to (10), wherein the material of the base forming layer is different from the material of the step forming layer.

[0279] (13) The light-emitting device according to (1), wherein the step-forming layer includes a first layer formed of a first material and a second layer formed of a second material different from the first material and provided on the first layer.

[0280] (14) The light-emitting device according to (1), further comprising an oxide confinement layer for confining a current between the substrate and the step.

[0281] (15) The light emitting device according to (1), further comprising a structure for current confinement between the substrate and the step, other than an oxide confinement layer.

[0282] (16) The light emitting device according to (1), wherein the substrate, the active layer, and the step forming layer constitute a plurality of light emitting elements.

[0283] (17) A light-emitting device comprising: a substrate; an active layer provided on the substrate; and a step-forming layer provided on the active layer and forming a step, wherein the step has, in a cross section perpendicular to a surface of the substrate, a first side on the substrate side, an upper end portion on the opposite side of the substrate, and a fourth side between the first side and the upper end portion, the fourth side having a curved shape or a linear shape, and an angle between the first side and a second line connecting the end of the first side and the upper end portion is 30 degrees or less.

[0284] (18) The light emitting device according to (17), wherein the spot size of the light emitted from the light emitting device is 40% or more of the length of the first side.

[0285] (19) A method for manufacturing a light-emitting device, comprising: forming an active layer on a substrate; forming a step-forming layer on the active layer; and forming a step in the step-forming layer; wherein the step is formed to have a first side on the substrate side and a second side on the opposite side of the substrate in a cross section perpendicular to a surface of the substrate; the length of the second side is set to be shorter than the length of the first side; and the angle between the first side and a first line connecting an end of the first side and an end of the second side is set to be 30 degrees or less.

[0286] (20) The method for manufacturing a light-emitting device described in (19), wherein the step of the step-forming layer is formed by: forming a step of a resist layer on the step-forming layer; balling up the step of the resist layer by reflow; etching the step-forming layer using the step of the balled-up resist layer as a mask; and finishing the etching of the step-forming layer before the step of the balled-up resist layer disappears.

[0287] 1: Substrate, 2: Lower mirror, 2a: Mirror, 2b: Mirror, 3: Lower cladding layer, 4: Active layer, 4a: Lower active layer, 4b: Intermediate active layer, 4c: Upper active layer, 5: Upper cladding layer, 6: Upper mirror, 6a: Mirror, 6b: Mirror, 7: Base forming layer, 8: Step forming layer, 8a: Lower layer, 8b: Upper layer, 9: Step forming layer, 10: Resist layer, 11: Ion implantation region, 12: Upper electrode, 13: Lower electrode, 14: Contact layer, 15: Oxidized constriction layer, 16: AR coating film, 17: TJ layer, 18: TJ layer, 19: Ion implantation region, 20: Vehicle, 20a: Vehicle control system, 21: Vehicle control ECU, 22: Communication unit, 23: Map information storage unit, 24: Position information acquisition unit, 25: External recognition sensor, 26: In-vehicle sensor, 27: Vehicle sensor, 31: Memory unit, 32: Cruise assist / 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: Operation 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 side optical system, 106: Light receiving side optical system, 107: Light receiving unit, 108: Signal processing unit, 109: control unit, 109a: distance measurement unit, 110: temperature detection unit

Claims

1. A light emitting device comprising: a substrate; an active layer provided on the substrate; and a step forming layer provided on the active layer and forming a step, wherein the step has, in a cross section perpendicular to the surface of the substrate, a first side on the substrate side and a second side on the opposite side of the substrate, the length of the second side being shorter than the length of the first side, and the angle between the first side and a first line connecting an end of the first side and an end of the second side being 30 degrees or less.

2. The light emitting device according to claim 1, wherein the angle between the first side and the first straight line is 20 degrees or less.

3. The light emitting device according to claim 1, wherein the angle between the first side and the first straight line is 10 degrees or less.

4. The light emitting device according to claim 1, wherein the spot size of the light emitted from said light emitting device is 40% or more of the length of said first side.

5. The light emitting device according to claim 1, further comprising a first reflector provided below the active layer on the substrate, and / or a second reflector provided above the active layer on the substrate.

6. The light emitting device according to claim 5, wherein the second reflecting mirror includes a first portion provided below the step and a second portion provided above the step.

7. The light-emitting device according to claim 1, wherein the step further has a third side between the first side and the second side in a cross section perpendicular to the surface of the substrate, and the third side has a curved shape.

8. The light-emitting device according to claim 1, wherein the step further has a third side between the first side and the second side in a cross section perpendicular to the surface of the substrate, and the third side has a linear shape.

9. The light emitting device according to claim 1, wherein the step has a circular, elliptical, or polygonal shape in plan view.

10. The light emitting device according to claim 1, further comprising an undercoat forming layer provided between said active layer and said step forming layer, forming an undercoat of said step.

11. The light-emitting device according to claim 10, wherein the material of the base forming layer is the same as the material of the step forming layer.

12. The light-emitting device according to claim 10, wherein the material of the base forming layer is different from the material of the step forming layer.

13. The light-emitting device according to claim 1, wherein the step-forming layer includes a first layer formed of a first material and a second layer formed of a second material different from the first material and provided on the first layer.

14. The light emitting device according to claim 1, further comprising an oxide confinement layer for confining current between the substrate and the step.

15. The light emitting device according to claim 1, further comprising a structure for confining current between said substrate and said step, other than an oxide confinement layer.

16. The light emitting device according to claim 1, wherein the substrate, the active layer, and the step forming layer constitute a plurality of light emitting elements.

17. A light-emitting device comprising: a substrate; an active layer provided on the substrate; and a step-forming layer provided on the active layer and forming a step, wherein the step has, in a cross section perpendicular to the surface of the substrate, a first side on the substrate side, an upper end portion on the opposite side of the substrate, and a fourth side between the first side and the upper end portion, the fourth side having a curved shape or a linear shape, and the angle between the first side and a second line connecting the end of the first side and the upper end portion is 30 degrees or less.

18. The light emitting device according to claim 17, wherein the spot size of the light emitted from the light emitting device is 40% or more of the length of the first side.

19. A method for manufacturing a light-emitting device, comprising: forming an active layer on a substrate; forming a step-forming layer on the active layer; and forming a step in the step-forming layer, wherein the step is formed to have a first side on the substrate side and a second side on the opposite side of the substrate in a cross section perpendicular to the surface of the substrate, the length of the second side is set to be shorter than the length of the first side, and the angle between the first side and a first line connecting an end of the first side and an end of the second side is set to be 30 degrees or less.

20. A method for manufacturing a light-emitting device as described in claim 19, wherein the step in the step-forming layer is formed by: forming a step in a resist layer on the step-forming layer; balling up the step in the resist layer by reflow; etching the step-forming layer using the step in the balled-up resist layer as a mask; and finishing the etching of the step-forming layer before the step in the balled-up resist layer disappears.

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