Light-emitting element

Abstract

[Problem] To provide a light-emitting element which does not adversely affect light-emitting characteristics while realizing a mesa-less structure. [Solution] In the present invention, an in-plane position of a semiconductor insulation region including an active layer is surrounded at a position separated by 0.5 μm or more outward from a light beam shape. Due to this configuration, a reactive current can be suppressed by narrowing the current to the shape and size as intended during ion implantation, and light absorption loss can be reduced. In addition, by covering the upper part of a step with a dielectric mirror, unintended positional deviation of the light beam can be prevented, and the reduction of the light absorption loss can be surely realized.

Description

Light-emitting element

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

[0002] In GaAs-based VCSEL (Vertical Cavity Surface Emitting Laser) structures, oxidation of the AlAs layer is often used as a means of confining the current / optical field. To oxidize the AlAs layer, it is necessary to etch a part of the stack of the light-emitting element into a mesa shape and expose the end face of the AlAs layer.

[0003] If the etching process for processing the mesa shape can be omitted, process damage to the light-emitting element can be suppressed, and the mesa-less structure can simplify the manufacturing process. Furthermore, there is no need to secure in-plane space for mesa etching, and the pitch between elements can be narrowed, which has the advantage of increasing the yield of elements obtained from a wafer.

[0004] To realize a mesare-less structure, it is necessary to constrict the current / optical field by a means other than oxidation of the AlAs layer. For example, Patent Document 1 discloses a technique in which a central conductive channel core is disposed above the active layer, and impurities are implanted from above to form an insulated blocking region around the central conductive channel core, thereby narrowing the range of current flowing in the active region.

[0005] Patent No. 6853349

[0006] However, with the technology disclosed in Patent Document 1, if the insulating region formed by ion implantation or the like does not reach the active layer, the carriers may spread in the in-plane direction before reaching the active layer or in the active layer, and the current confinement may not necessarily be in the shape and size intended by the ion implantation. In other words, the component of the injected carriers that does not contribute to light emission increases, causing a decrease in light emission efficiency. This problem will be referred to as the first problem below.

[0007] The first problem mentioned above can be solved by extending the insulating region formed by ion implantation or the like to the active layer. However, this would make it easier for optical absorption loss to occur. This is because the insulated active layer becomes an absorbing layer, and if a light beam is present nearby, it will act as a source of absorption loss and adversely affect the characteristics of the VCSEL. Hereinafter, this problem will be referred to as the second problem.

[0008] There is a trade-off between preventing the diffusion of carriers to achieve the desired current confinement and avoiding light absorption loss in the active layer. Patent Document 1 does not disclose a method for solving both the first and second problems described above.

[0009] Therefore, the present disclosure provides a light-emitting element that can solve both the first and second problems described above, without reducing the luminous efficiency and without adversely affecting the luminous characteristics.

[0010] In order to solve the above problems, according to the present disclosure, a light emitting device may include a first reflective layer and a second reflective layer spaced apart along the optical axis direction, an active layer having a current confinement region and disposed between the first reflective layer and the second reflective layer, a first contact layer and a second contact layer spaced apart along the optical axis direction and passing a current through the active layer, and a step portion disposed between the first contact layer and the first reflective layer.

[0011] The planar shape of the step portion is such that the light intensity of the near-field pattern profile of the emitted light is 1 / e ２ The shape may be similar to the light beam shape defined within the above range.

[0012] The active layer may have a semiconductor insulating region, and the in-plane position of the semiconductor insulating region may have an outer size that surrounds the light beam shape of the emitted light at a position 0.5 μm or more away from the light beam shape when viewed in a plan view.

[0013] The first reflective layer may be arranged to cover the side and top surfaces of the step portion and may be made of a dielectric material.

[0014] The step portion may have a semiconductor layer whose side and top surfaces are covered with the first reflective layer.

[0015] The semiconductor layer may comprise the same semiconductor material as the first contact layer.

[0016] The semiconductor layer may comprise a different semiconductor material than the first contact layer.

[0017] The step portion may have a first dielectric layer, and the first reflective layer may be composed of a second dielectric layer arranged to cover the side and top surfaces of the first dielectric layer and containing a dielectric material different from that of the first dielectric layer.

[0018] The first reflective layer that overlaps with the peripheral portion of the light beam propagating in the optical axis direction may reflect light of a different wavelength from that of the first reflective layer that overlaps with the central portion of the light beam.

[0019] The peripheral portion of the step portion may have a thickness in the optical axis direction that is different from that of the central portion.

[0020] The step portion may have a semiconductor layer whose thickness in the optical axis direction is different between the central portion and the peripheral portion, and the first reflective layer may have a dielectric layer covering a surface of the semiconductor layer.

[0021] The semiconductor device may comprise a first cladding layer disposed between the first contact layer and the active layer, and a second cladding layer disposed between the second contact layer and the active layer, wherein the first cladding layer may have an insulating region that does not allow current to flow from the first contact layer at a location that does not overlap with the step portion when viewed in a plane.

[0022] The light emitting device may further include a third reflective layer disposed between the first contact layer and the first cladding layer.

[0023] The semiconductor device may further include divided insulating regions that divide the first contact layer into a plurality of regions in a plane, and the width of the divided insulating regions in the plane direction may be narrower than the width of the insulating region in the plane direction.

[0024] A plurality of the first reflective layers corresponding to the plurality of first contact layers divided by the dividing insulating regions and one second reflective layer may be provided.

[0025] The optical fiber includes: a tunnel junction layer disposed between two adjacent active layers in the optical axis direction among the plurality of active layers disposed at a distance from each other in the optical axis direction; and a plurality of first cladding layers and a plurality of second cladding layers disposed on both sides of each of the plurality of active layers in the optical axis direction, with each of the plurality of first cladding layers sandwiched between them, wherein the plurality of first cladding layers contain p-type impurities, and the plurality of second cladding layers contain n-type impurities, each of the plurality of first cladding layers has the insulating region, and among the plurality of second cladding layers, the second cladding layers other than the second cladding layer closest to the second contact layer may have the insulating region.

[0026] The second reflective layer may be disposed between the second contact layer and the active layer.

[0027] The second contact layer may be disposed between the second reflective layer and the active layer.

[0028] The second contact layer may be disposed inside the second reflective layer.

[0029] 6A . A cross-sectional view of a light-emitting element according to a first embodiment of the present disclosure. FIG. 1 is a diagram showing the relationship between a current flowing in an active layer and light emission output. Cross-sectional views illustrating manufacturing steps of a light-emitting element according to the first embodiment. Cross-sectional views following FIG. 3A . Cross-sectional views following FIG. 3B . Cross-sectional views following FIG. 3C . Cross-sectional views following FIG. 3D . Cross-sectional views following FIG. 3E . Cross-sectional views following FIG. 3F . Cross-sectional views following FIG. 3G . Cross-sectional views of a light-emitting element according to a second embodiment of the present disclosure. Cross-sectional views of a light-emitting element according to a third embodiment of the present disclosure. Cross-sectional views illustrating a step of removing a semiconductor layer and an etching stop layer other than a step portion. Cross-sectional views following FIG. 6A . Cross-sectional views following FIG. 6B . Cross-sectional views of a light-emitting element according to a fourth embodiment of the present disclosure. Cross-sectional views illustrating a step of forming a step portion. Cross-sectional views following FIG. 8A . Cross-sectional views following FIG. 8B . Cross-sectional views following FIG. 8C . Cross-sectional views of a step portion of a light-emitting element according to a fifth embodiment of the present disclosure. Cross-sectional views illustrating a manufacturing step of a step portion of a light-emitting element according to the fifth embodiment. Cross-sectional views following FIG. 10A . Cross-sectional views following FIG. 10B . 10C. Cross-sectional view of a step portion of a light-emitting element according to a sixth embodiment of the present disclosure. Cross-sectional views of processes showing a manufacturing process of a step portion of a light-emitting element according to the sixth embodiment. Cross-sectional views of processes following FIG. 12A. Cross-sectional views of processes following FIG. 12B. Cross-sectional views of processes following FIG. 12C. Cross-sectional views of a light-emitting element according to a seventh embodiment of the present disclosure. Cross-sectional views of a light-emitting element according to a seventh embodiment of the present disclosure. Cross-sectional views of processes showing a manufacturing process of a light-emitting element according to the seventh embodiment. Cross-sectional views of processes following FIG. 14A. Cross-sectional views of processes following FIG. 14B. Cross-sectional views of processes following FIG. 14C. Cross-sectional views of processes following FIG. 14D. Cross-sectional views of processes following FIG. 14E. Cross-sectional views of processes following FIG. 14F. Cross-sectional views of processes following FIG. 14G. Cross-sectional views of processes following FIG. 14H. Cross-sectional views of a light-emitting element according to an eighth embodiment of the present disclosure. Cross-sectional views of a light-emitting element according to a ninth embodiment of the present disclosure. Block diagram showing a configuration example of a ranging system. Explanatory diagram of an STL system. Explanatory diagram of the ranging principle of the STL system. Block diagram showing an example of the general configuration of a vehicle control system. Explanatory diagram showing an example of the installation positions of an outside vehicle information detection unit and an imaging unit.

[0030] Hereinafter, embodiments of the light-emitting device will be described with reference to the drawings. The following description will focus on the main components of the light-emitting device, but the light-emitting device may include components or functions that are not shown or described. The following description does not exclude components or functions that are not shown or described.

[0031] 1 is a cross-sectional view of a light-emitting element 1 according to a first embodiment of the present disclosure. While Fig. 1 shows the cross-sectional structure of one light-emitting element 1, it is also possible to realize a surface-emitting element 1 having a VCSEL (Vertical Cavity Surface Emitting Laser) structure in which a plurality of light-emitting elements 1 having the same cross-sectional structure as Fig. 1 are arranged on a surface.

[0032] 1 , the light-emitting element 1 according to the first embodiment includes a first reflective layer 2, a second reflective layer 3, an active layer 4, a first contact layer 5, a second contact layer 6, and a step portion 7. Hereinafter, the first reflective layer 2 may be referred to as the upper mirror layer 2, the second reflective layer 3 as the lower mirror layer 3, the first contact layer 5 as the upper contact layer 5, and the second contact layer 6 as the lower contact layer 6.

[0033] The upper mirror layer 2 and the lower mirror layer 3 are spaced apart along the optical axis. The upper mirror layer 2 is, for example, a dielectric multilayer film made of a dielectric material. The lower mirror layer 3 is, for example, a semiconductor multilayer film made of a p-type semiconductor material.

[0034] The active layer 4 is disposed between the upper mirror layer 2 and the lower mirror layer 3. The active layer 4 has a current confinement region. A current flows through the current confinement region of the active layer 4, and this current causes light to be emitted in the current confinement region. As shown in FIG. 1 , the light intensity of the optical field 4a in the current confinement region is greatest in the center of the current confinement region and decreases toward the periphery of the current confinement region. The light emitted in the active layer 4 propagates in at least a portion of the current confinement region. In this specification, the range through which the light emitted in the active layer 4 propagates is referred to as the light beam range.

[0035] A semiconductor insulating region is provided around the current confinement region of the active layer 4. The in-plane position of the semiconductor insulating region has an outer size that surrounds the light beam shape at a position 0.5 μm or more away from the light beam shape when viewed in plan.

[0036] The upper contact layer 5 and the lower contact layer 6 are arranged at a distance from each other along the optical axis direction. The upper contact layer 5 is connected to an upper metal layer 8. The lower contact layer 6 is connected to a lower metal layer 9. By applying a voltage between the upper metal layer 8 and the lower metal layer 9, a current can be passed from the lower contact layer 6 to the upper contact layer 5 through the current confinement region of the active layer 4. This current causes the active layer 4 to emit light. The upper metal layer 8 is, for example, an N-electrode, and the lower metal layer 9 is, for example, a P-electrode.

[0037] A convex step portion 7 is provided on the upper contact layer 5. The side and top surfaces of the step portion 7 are covered with the upper mirror layer 2. More specifically, the step portion 7 is disposed between the upper contact layer 5 and the upper mirror layer 2.

[0038] The step portion 7 according to the first embodiment has a semiconductor layer 10 whose side and top surfaces are covered by the upper mirror layer 2. That is, the dielectric multilayer film constituting the upper mirror layer 2 covers the top and side surfaces of the semiconductor layer 10 in the step portion 7. The semiconductor layer 10 constituting the step portion 7 is formed by etching away a part of the upper contact layer 5. The size of the semiconductor layer 10 constituting the step portion 7 in the plane direction defines the light propagation range (optical field).

[0039] The planar shape of the step portion 7 is such that the light intensity of the near-field pattern profile of the emitted light is 1 / e ２ The shape is similar to the beam shape defined within the above range.

[0040] 1 , the light-emitting device 1 according to the first embodiment also includes a first cladding layer 11, a second cladding layer 12, a GaAs substrate 13, and an anti-reflection layer 16. Hereinafter, the first cladding layer 11 may be referred to as the upper cladding layer 11, and the second cladding layer 12 may be referred to as the lower cladding layer 12.

[0041] The upper cladding layer 11 is disposed between the upper contact layer 5 and the active layer 4. The lower cladding layer 12 is disposed between the lower contact layer 6 and the active layer 4.

[0042] As will be described later, a patterned resist film is disposed on a part of the upper contact layer 5, and then impurity ions are implanted from above the upper contact layer 5. The patterned resist film has an area larger than the step portion 7.

[0043] As a result, impurity ions are implanted into the upper contact layer 5, the upper cladding layer 11, and the active layer 4 at locations that do not overlap with the resist film in plan view, forming insulating regions 15. Some of the impurity ions are also implanted into the lower cladding layer 12, but it is not necessary to form a complete insulating region 15 in the lower cladding layer 12. This is because current confinement can be achieved as long as the active layer is insulated.

[0044] A lower contact layer 6 is stacked on a GaAs substrate 13. A lower mirror layer 3 is disposed on the lower contact layer 6. A lower cladding layer 12 is disposed on the lower mirror layer 3. An active layer 4 is disposed on the lower cladding layer 12. An upper cladding layer 11 is disposed on the active layer 4. An upper contact layer 5 is disposed on the upper cladding layer 11. A step portion 7 is disposed on the upper contact layer 5. An upper mirror layer 2 is disposed on the step portion 7. An upper metal layer 8 is disposed on the upper mirror layer 2. An antireflection layer 16 is disposed below the GaAs substrate 13. The antireflection layer 16 is, for example, a dielectric material such as SiN.

[0045] Light emitted from the active layer 4 resonates between the upper mirror layer 2 and the lower mirror layer 3, and when the light intensity exceeds a predetermined threshold, it passes through the antireflection layer 16 and is emitted.

[0046] Figure 2 shows the relationship between the current flowing through the active layer 4 and the light emission output. Figure 2 shows three curves w1 to w3 that indicate the above-mentioned relationship when an insulating region (semiconductor insulating region) 15 is provided at three different distances outside the optical field 4a in the current confinement region of the active layer 4. Curve w1 represents the case where the distance is 0 μm, curve w2 represents the case where the distance is 0.5 μm, and curve w3 represents the case where the distance is 1.0 μm. As shown in the figure, sufficient light emission output can be obtained if the distance is 0.5 μm or more.

[0047] Therefore, if the semiconductor insulating region 15 has an outer size that surrounds the light beam shape of the light field 4a at a position 0.5 μm or more outward from the light beam shape in a plan view, it is possible to suppress light absorption loss and also suppress reactive current, thereby obtaining sufficient light output. Note that in a surface-emitting light emitting element 1 with a VCSEL structure, the size of each light emitting element 1 must be as small as possible, so it is desirable that the semiconductor insulating region 15 have an outer size of within 10 μm that surrounds the light field 4a in the step portion 7.

[0048] In addition, if the upper mirror layer 2 that directly covers the step portion is made of a dielectric multilayer film, there is an advantage in that it can prevent misalignment of the light beam. If the upper mirror layer 2 that directly covers the step portion is made of a semiconductor, the position of the convex shape inherited on the surface of the upper mirror layer 2 will be formed at a position that is shifted in the in-plane direction from the position of the step portion due to the influence of crystalline anisotropy. In that case, the light beam position determined by the position of the convex shape will deviate from the original target, and the light beam will be closer to the semiconductor insulating region than expected, which may result in absorption loss.

[0049] 3A to 3H are cross-sectional views illustrating the manufacturing process of the light-emitting device 1 according to the first embodiment. First, as shown in FIG. 3A, a lower contact layer 6, a lower mirror layer 3, and a lower cladding layer 12 made of an AlGaAs-based semiconductor are formed by crystal growth on a GaAs substrate 13, for example, in wafer form. Next, an active layer 4 made of an InGaAs-based semiconductor with an oscillation wavelength of 920 nm to 960 nm is formed by crystal growth on the lower cladding layer 12. Next, an upper cladding layer 11 and an upper contact layer 5 made of an AlGaAs-based semiconductor are formed by crystal growth on the active layer 4. The layers on the lower side are p-type, and the layers on the upper side are n-type. The upper side can be called the cathode, and the lower side can be called the anode.

[0050] 3B , a resist film 21 is applied onto the upper contact layer 5 and patterned, and the resist film 21 is removed from areas other than where the step portion 7 will be located. In this state, impurity ions are implanted from above the upper contact layer 5, and the implanted locations of the impurity ions in the upper contact layer 5, upper cladding layer 11, and active layer 4 become insulating regions 15. The area of ​​the patterned resist film 21 is larger than the area of ​​the step portion 7 that will be formed in a process described below.

[0051] The patterned resist film 21 functions as a mask member during ion implantation. At this time, implantation energy is applied so that the impurity ions reach the active layer 4. As a result, a current confinement region is formed in the active layer 4.

[0052] 3C , the upper contact layer 5 is patterned using a resist film 21 processed to fit the outer size of the step portion 7 as a mask, leaving the upper contact layer 5 thick only directly below the resist film 21, and removing and thinning the rest of the upper contact layer 5. This forms a step portion 7 in part of the upper contact layer 5. This step portion 7 is a semiconductor layer 10 made of the same semiconductor material as the upper contact layer 5.

[0053] Next, as shown in Fig. 3D, after removing the resist film 21, a dielectric multilayer film (upper mirror layer) 2 is formed on the upper contact layer 5 and the step portion 7. Each dielectric layer constituting the dielectric multilayer film 2 is formed in a superlattice shape so that the optical film thickness is λ / 4 where λ is the target wavelength. The material of the dielectric multilayer film is, for example, SiO ２ / Si, etc. Then, a part of the dielectric multilayer film 2 is removed by etching, and the dielectric multilayer film (upper mirror layer) 2 is formed only on the top surface and side surfaces of the step portion 7 .

[0054] Next, as shown in FIG. 3E, a resist film 21 is formed on the surface other than the step portion 7, and an upper metal layer 8 is formed thereon by vacuum deposition or sputtering, and then the upper metal layer 8 is removed from the surface other than the step portion 7 by lift-off.

[0055] 3F , the lower cladding layer 12, the active layer 4, the upper cladding layer 11, and the upper contact layer 5 are each partially etched away to expose a portion of the lower contact layer 6. Specifically, a resist film is patterned so that the non-etched regions are masked, and then the lower cladding layer 12, the active layer 4, the upper cladding layer 11, and the upper contact layer 5 are partially etched away by, for example, RIE (Reactive Ion Etching) to expose a portion of the lower contact layer 6.

[0056] Next, as shown in FIG. 3G, a lower metal layer 9 is formed on a portion of the lower contact layer 6 by, for example, a lift-off method.

[0057] 3H, the back surface of the GaAs substrate 13 is thinned by CMP (Chemical Mechanical Polishing) or the like, and a dielectric film is formed on the back surface of the GaAs substrate 13. This dielectric film functions as an anti-reflection layer 16. The material of the dielectric film is, for example, SiN.

[0058] Next, the wafer is diced into individual pieces and packaged to obtain the surface light emitting device 1 having the VCSEL structure.

[0059] Second Embodiment Fig. 4 is a cross-sectional view of a light-emitting element 1a according to a second embodiment of the present disclosure. In Fig. 4, the same components as those in Fig. 1 are denoted by the same reference numerals, and the following description will focus on the differences.

[0060] The light-emitting element 1a of the second embodiment differs from the light-emitting element 1 of the first embodiment in that a new upper mirror layer (third reflective layer) 22 is disposed between the upper contact layer 5 and the upper cladding layer 11.

[0061] Hereinafter, the upper mirror layer 2 covering the side and top surfaces of the step portion 7 will be referred to as the first upper mirror layer 2, and the upper mirror layer 22 disposed between the upper contact layer 5 and the upper cladding layer 11 will be referred to as the second upper mirror layer 22.

[0062] The second upper mirror layer 22 is a semiconductor multilayer film, and is formed of, for example, an AlGaAs-based semiconductor material. Each layer constituting the second upper mirror layer 22 is formed in a superlattice shape so that the optical film thickness is λ / 4 where λ is the target wavelength. The combination of each layer of the second upper mirror layer 22 is, for example, Al ０．９ GaAs / GaAs, etc.

[0063] The manufacturing process of the light emitting device 1a according to the second embodiment is the same as that shown in FIG. 3 except that a step of forming a second upper mirror layer 22 on the upper cladding layer 11 is added.

[0064] By providing the second upper mirror layer 22, it is possible to reduce the scattering loss of light at the step portion 7 and the light absorption in the first upper mirror layer 2 made of a dielectric multilayer film.

[0065] Third Embodiment Fig. 5 is a cross-sectional view of a light-emitting element 1b according to a third embodiment of the present disclosure. In Fig. 5, the same components as those in Fig. 1 are denoted by the same reference numerals, and the following description will focus on the differences.

[0066] In the light emitting device 1 b according to the third embodiment, the material of the semiconductor layer 10 in the step portion 7 is a semiconductor material different from that of the upper contact layer 5 .

[0067] In the third embodiment, after the upper contact layer 5 is formed on the upper cladding layer 11, an etching stop layer 23 is formed on the upper contact layer 5, and then a semiconductor layer 10a made of a semiconductor material different from that of the upper contact layer 5 is formed thereon. Thereafter, the semiconductor layer 10a and the etching stop layer 23 are partially etched away to leave the etching stop layer 23 and the semiconductor layer 10a in the step portion 7.

[0068] 6A to 6C are cross-sectional views illustrating the process of removing the semiconductor layer 10a and the etching stop layer 23 from areas other than the step portion 7. As shown in FIG. 6A, the etching stop layer 23 is formed on the upper contact layer 5, and the semiconductor layer 10a is formed thereon. Next, as shown in FIG. 6B, the semiconductor layer 10a is etched away from areas other than the step portion 7 to expose the etching stop layer 23. Thereafter, as shown in FIG. 6C, the etching stop layer 23 is removed when a dielectric multilayer film is formed on the step portion 7. This allows the etching stop layer 23 and the semiconductor layer 10a to remain only in the step portion 7.

[0069] As described above, in the third embodiment, the etching stop layer 23 and the semiconductor layer 10a are sequentially formed on the upper contact layer 5, so that the etching stop layer 23 can prevent excessive etching, making it easy to leave the semiconductor layer 10a only in the step portion 7. This allows the height of the step portion 7 to be formed with good controllability.

[0070] 7 is a cross-sectional view of a light-emitting device 1c according to a fourth embodiment of the present disclosure. In Fig. 7, the same components as those in Fig. 1 are denoted by the same reference numerals, and the following description will focus on the differences.

[0071] The light emitting element 1c according to the fourth embodiment differs from the light emitting element 1 according to the first embodiment in that the step portion 7 is formed of a dielectric layer.

[0072] More specifically, in the light-emitting device 1c according to the fourth embodiment, the step portion 7 is formed of a first dielectric multilayer film 24. An upper mirror layer 2 is disposed so as to cover the top and side surfaces of this first dielectric multilayer film 24. The upper mirror layer 2 is a second dielectric multilayer film 2 made of the same or a different material from the dielectric multilayer film of the step portion 7.

[0073] 8A to 8D are cross-sectional views showing the steps of forming the step portion 7. First, as shown in Fig. 8A, a first dielectric multilayer film 24 is formed on the upper contact layer 5. Next, as shown in Fig. 8B, a portion of the first dielectric multilayer film 24 is etched away, leaving the first dielectric multilayer film 24 only in the step portion 7.

[0074] 8C , the second dielectric multilayer film 2 is formed on the upper contact layer 5 and the first dielectric multilayer film 24. As a result, the top and side surfaces of the first dielectric multilayer film 24 are covered with the second dielectric multilayer film 2.

[0075] 8D, the second dielectric multilayer film 2 is etched away from the step portion 7 so that the first dielectric multilayer film 24 and the second dielectric multilayer film 2 remain only in the step portion 7. The manufacturing process is the same as that shown in FIG. 3 except for the step of forming the step portion 7.

[0076] In this way, by providing two types of dielectric multilayer films 2 and 24 on the step portion 7, the scattering loss of light can be further suppressed.

[0077] Fifth Embodiment A light-emitting device 1d according to a fifth embodiment differs from the light-emitting device 1c according to the first to fourth embodiments in that the upper mirror layer 2 has a distribution in the design reflection wavelength in the in-plane direction.

[0078] In an actual surface-emitting device 1 with a VCSEL structure, the gain peak wavelength may vary within the surface due to temperature distribution. For example, the peripheral portion of the light beam range is relatively hotter than the central portion, and therefore the wavelength tends to be longer. In this case, if the designed reflection wavelength in the peripheral portion of the light beam range is set to be the same as that in the central portion, the reflection loss in the peripheral portion will increase.

[0079] Therefore, in the fifth embodiment, the designed reflection wavelength in the peripheral portion of the upper mirror layer 2 is set to be longer than that in the central portion.

[0080] 9 is a cross-sectional view of a step portion 7 of a light-emitting element 1d according to a fifth embodiment of the present disclosure. In Fig. 9, the same components as those in Fig. 1 are denoted by the same reference numerals, and the following description will focus on the differences.

[0081] As shown in Fig. 9, the light-emitting element 1d according to the fifth embodiment has an upper mirror layer 2 having different reflection wavelengths in the central portion 7b and the peripheral portion 7c. The light-emitting element 1d is designed so that the first dielectric multilayer film 25 in the peripheral portion 7c reflects relatively longer wavelengths than the second dielectric multilayer film 2 disposed in the central portion 7b of the upper mirror layer 2 shown in Fig. 9. The second dielectric multilayer film 2 is left in the peripheral portion 7c as well, because it is physically difficult to selectively remove the second dielectric multilayer film 2 and leave the second dielectric multilayer film 2 only in the central portion 7b.

[0082] 10A to 10D are cross-sectional views showing the steps of fabricating the step portion 7 of the light-emitting element 1d according to the fifth embodiment. First, a portion of the upper contact layer 5 is etched away to form the step portion 7. Next, as shown in FIG. 10A, a first dielectric multilayer film 25 is formed on the upper contact layer 5 and the step portion 7. The thickness of each layer of the first dielectric multilayer film 25 is set to λ / 4 or more with respect to the target wavelength λ, taking into account the shift to longer wavelength due to temperature distribution. The material of the first dielectric multilayer film 25 is, for example, SiO ２ / Si, etc.

[0083] Next, as shown in FIG. 10B, the first dielectric multilayer film 25 other than the stepped portion 7 and the first dielectric multilayer film 25 at the central portion 7b of the stepped portion 7 are removed by etching.

[0084] 10C, the second dielectric multilayer film 2 is formed on the first dielectric multilayer film 25 and the upper contact layer 5. Next, as shown in FIG. 10D, the second dielectric multilayer film 2 is etched away except for the step portion 7.

[0085] As a result, the second dielectric multilayer film 2 is disposed in the central portion 7b of the step portion 7, and the first dielectric multilayer film 25 and the second dielectric multilayer film 2 are stacked in the peripheral portion 7c.

[0086] Sixth Embodiment Fig. 11 is a cross-sectional view of a step portion 7 of a light-emitting element 1e according to a sixth embodiment of the present disclosure. In Fig. 11, the same components as those in Fig. 1 are denoted by the same reference numerals, and the following description will focus on the differences.

[0087] The light-emitting element 1e according to the sixth embodiment differs from the light-emitting element 1 according to the first embodiment in that the height of the step portion 7 has an in-plane distribution. As shown in Fig. 11 , the peripheral portion 7c of the step portion 7 has a thickness in the optical axis direction that is different from that of the central portion 7b. The step portion 7 has a semiconductor layer 10 whose thickness in the optical axis direction is different between the central portion 7b and the peripheral portion 7c. The upper mirror layer 2 has a dielectric layer covering the upper surface of the semiconductor layer 10.

[0088] Higher-order modes are likely to occur in the peripheral portion 7c of the light beam range. To suppress higher-order modes, the peripheral portion 7c and the central portion 7b of the step portion 7 are made to have different heights, making it difficult to achieve phase matching with the upper mirror layer 2 in the peripheral portion 7c. This increases the reflection loss in the peripheral portion 7c of the step portion 7, thereby suppressing the effects of higher-order modes. As described above, the step portion 7 in the light-emitting device 1e according to the sixth embodiment has different thicknesses in the optical axis direction between the central portion 7b and the peripheral portion 7c, and the peripheral portion 7c of the step portion 7 is thicker in the optical axis direction than the central portion 7b. According to the sixth embodiment, the effects of unintended higher-order modes on the far field pattern can be reduced.

[0089] 12A to 12D are cross-sectional views showing the steps of fabricating the step portion 7 of the light-emitting element 1e according to the sixth embodiment. Fig. 12A shows the upper contact layer 5 formed by crystal growth on the upper cladding layer 11. As shown in Fig. 12B, a resist film 26 is used as a mask to etch away a portion of the upper contact layer 5, thereby forming the step portion 7.

[0090] 12C, another resist film 26 is used as a mask to etch away a portion of the upper contact layer 5 in the central portion 7b of the step portion 7. Next, as shown in Fig. 12D, the resist film 26 is removed. As a result, the thickness of the peripheral portion 7c of the semiconductor layer 10 in the step portion 7 becomes thicker than that of the central portion 7b.

[0091] 11, a dielectric multilayer film that will become the upper mirror layer 2 is formed on the upper contact layer 5. The optical thickness of each dielectric layer that constitutes the dielectric multilayer film is set to λ / 4 where λ is the target wavelength. The material of the dielectric multilayer film is, for example, SiO ２ / Si, etc. A part of the dielectric multilayer film is removed by etching to leave the dielectric multilayer film only on the step portion 7. The subsequent steps are the same as those shown in FIG.

[0092] As can be seen from FIG. 12D, a recess is formed in the central portion 7b of the step portion 7, the cavity length differs between the central portion 7b and the peripheral portion 7c, and it becomes difficult to achieve phase matching in the peripheral portion 7c.

[0093] As described above, in the sixth embodiment, a recess is formed in the central portion 7 b of the step portion 7, and the upper mirror layer 2 is formed to a uniform thickness on the peripheral portion 7 c of the step portion 7 and on the central portion 7 b. Therefore, the resonator length differs between the central portion 7 b and the peripheral portion 7 c of the upper mirror layer 2, making it difficult to achieve phase matching with the upper mirror layer 2 in the peripheral portion 7 c of the step portion 7, and making it possible to suppress the influence of higher-order modes that are more frequently generated in the peripheral portion 7 c of the step portion 7.

[0094] Seventh Embodiment Fig. 13 is a cross-sectional view of a light-emitting element 1f according to a seventh embodiment of the present disclosure. In Fig. 13, components common to those in Fig. 1 are assigned the same reference numerals, and the following description will focus on the differences. The light-emitting elements 1f according to the seventh embodiment are arranged at regular intervals in a plane to form a surface-emitting element 1. A dividing insulating region 27 is arranged between two light-emitting elements 1 adjacent in the plane direction. The dividing insulating region 27 divides the upper contact layer 5 into multiple regions in the plane. The dividing insulating region 27 is formed, for example, by implanting impurity ions into the upper contact layer 5.

[0095] The width of the divided insulating region 27 is smaller than the width of the insulating region 15 provided in the upper contact layer 5, the upper cladding layer 11, and the active layer 4. By narrowing the width of the divided insulating region 27, a sufficient contact area between the upper metal layer 8 and the upper contact layer 5 can be secured, and the contact resistance between the upper metal layer 8 and the upper contact layer 5 can be reduced.

[0096] In this way, the upper contact layer 5 is divided into multiple pieces by the dividing insulating regions 27 provided at predetermined intervals in the plane. A plurality of light-emitting elements 1f divided by the dividing insulating regions 27 are arranged on the GaAs substrate 13. Each of the light-emitting elements 1f has a plurality of upper mirror layers 2 and one lower mirror layer 3 corresponding to the plurality of first contact layers 5 divided by the dividing insulating regions 27.

[0097] 14A to 14I are process diagrams showing the manufacturing process of the light-emitting device 1f according to the seventh embodiment. First, as shown in Fig. 14A, the lower contact layer 6, the lower mirror layer 3, the lower cladding layer 12, the active layer 4, and the upper cladding layer 11 are formed in this order on the GaAs substrate 13 by crystal growth.

[0098] 14B, a resist film 28 is applied to the upper cladding layer 11 and patterned, and then impurity ions are implanted using the resist film 28 as a mask. As a result, an insulating region 15 is formed in the upper cladding layer 11 and the active layer 4.

[0099] Next, as shown in FIG. 14C, the resist film 28 is removed and then the upper contact layer 5 is formed by crystal regrowth.

[0100] Next, as shown in FIG. 14D, a resist film 29 is applied onto the upper contact layer 5 and patterned, and then impurity ions are implanted using the resist film 29 as a mask.

[0101] 14E, after patterning the resist film 29, the upper contact layer 5 is partially removed by RIE to form the step portion 7. The subsequent steps shown in FIGS. 14F to 14J are the same as those shown in FIGS. 3D to 3H.

[0102] In this way, in the seventh embodiment, a divided insulating region 27 is provided in the upper contact layer 5 to fit between two adjacent light-emitting elements 1 in the plane, and the width of this divided insulating region 27 is made narrower than the width of the insulating region 15, so that the contact area between the upper contact layer 5 and the upper metal layer 8 does not need to be narrowed more than necessary, and contact resistance can be reduced.

[0103] Eighth Embodiment Fig. 15 is a cross-sectional view of a light-emitting device 1g according to an eighth embodiment of the present disclosure. In Fig. 15, the same components as those in Fig. 1 are denoted by the same reference numerals, and the following description will focus on the differences.

[0104] The light-emitting device 1g according to the eighth embodiment has a multi-junction structure having a plurality of active layers 4 sandwiching a tunnel junction layer 31. Although two active layers 4 are arranged in Fig. 15, three or more active layers 4 may be arranged.

[0105] Each active layer 4 is sandwiched between a p-type upper cladding layer 11 and an n-type lower cladding layer 12. When impurity ions are implanted from above the upper contact layer 5, an insulating region 15 is formed in all of the upper cladding layers 11, the tunnel junction layer 31, and the lower cladding layer 12 except for the lowest lower cladding layer 12. Current confinement is possible if the lowermost upper cladding layer 11 is insulated. This is because, if the p-type semiconductor is insulated, current diffusion is unlikely to occur even if the active layer and n-type semiconductor are not insulated. Therefore, there is no problem even if the insulating region 15 is not provided for the lowest lower cladding layer 12.

[0106] In this way, in the light emitting element 1 having a multi-junction structure, the current spreading can be suppressed by implanting impurity ions up to the lowermost upper cladding layer 11 .

[0107] Ninth Embodiment Fig. 16 is a cross-sectional view of a light-emitting device 1h according to a ninth embodiment of the present disclosure. In Fig. 16, the same components as those in Fig. 1 are denoted by the same reference numerals, and the following description will focus on the differences.

[0108] In the light-emitting device 1h according to the ninth embodiment, a lower contact layer 6 is provided inside the lower mirror layer 3 or between the lower mirror layer 3 and the active layer 4 (more specifically, between the lower mirror layer 3 and the lower cladding layer 12). Although an example in which the lower contact layer 6 is provided inside the lower mirror layer 3 is shown in Fig. 16, the lower contact layer 6 may also be provided between the lower mirror layer 3 and the lower cladding layer 12.

[0109] The closer the lower contact layer 6 is to the active layer 4, the lower the resistance of the current flowing through the active layer 4 can be, but on the other hand, the degree of light absorption in the lower contact layer 6 increases, resulting in a decrease in light emission efficiency.

[0110] Therefore, it is desirable to determine the location of the lower contact layer 6 taking into consideration the balance between the reduction in resistance and the reduction in light emission efficiency.

[0111] (Configuration of Distance Measuring System 40) FIG. 17 is a block diagram showing a configuration example of a distance measuring system 40 as an example of implementation of the light emitting element 1 according to this embodiment.

[0112] As shown in the figure, the distance measurement system 40 includes a light emitting unit 41, a driving unit 42, a power supply circuit 43, a light emitting side optical system 44, a light receiving side optical system 45, a light receiving unit 46, a signal processing unit 47, a control unit 48, and a temperature detection unit 49.

[0113] The light-emitting unit 41 emits light using a plurality of light sources. The light-emitting unit 41 and the light-emitting side optical system 44 correspond to the light-emitting element 1 described above. The light-emitting unit 41 can be configured using any of the light-emitting elements 1, 1a, 1b, and 1c according to the first to seventh embodiments (hereinafter, collectively referred to as the light-emitting element 1). The light-emitting unit 41 may also be, for example, a vertical external cavity surface-emitting laser (VECSEL) in which a plurality of light-emitting elements 1 are arranged in a one-dimensional or two-dimensional direction.

[0114] The drive unit 42 is configured to have a power supply circuit 43 for driving the light emitting unit 41. The power supply circuit 43 generates a power supply voltage (a drive voltage Vd described later) for the drive unit 42 based on an input voltage (an input voltage Vin described later) from, for example, a battery (not shown) or the like provided in the distance measuring system 40. The drive unit 42 drives the light emitting unit 41 based on the power supply voltage.

[0115] Light emitted from the light-emitting unit 41 is irradiated onto a subject (object) S, which is the target of distance measurement, via a light-emitting side optical system 44. The light thus irradiated is reflected from the subject S and enters the light-receiving surface of a light-receiving unit 46 via a light-receiving side optical system 45.

[0116] The light receiving unit 46 has a light receiving element such as a CCD (Charge Coupled Device) sensor or a CMOS (Complementary Metal Oxide Semiconductor) sensor, receives reflected light from the subject S that enters via the light receiving side optical system 45 as described above, converts the light into an electrical signal, and outputs the electrical signal. The light receiving unit 46 and the light receiving side optical system 45 constitute a light receiving device.

[0117] The light receiving unit 46 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 47 at the subsequent stage.

[0118] Furthermore, the light receiving unit 46 in this example outputs a frame synchronization signal Fs to the driving unit 42. This enables the driving unit 42 to cause the light emitting element 1 in the light emitting unit 41 to emit light at a timing according to the frame period of the light receiving unit 46.

[0119] The signal processing unit 47 has a signal processor such as a DSP (Digital Signal Processor), etc. The signal processing unit 47 performs various signal processes on the digital signal input from the light receiving unit 46.

[0120] The control unit 48 has, 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 42 for controlling the light-emitting operation by the light-emitting unit 41, and controls the light-receiving operation by the light-receiving unit 46.

[0121] The control unit 48 functions as a distance measuring unit 28a. The distance measuring unit 28a measures the distance to the subject S based on a signal input via the signal processing unit 47 (i.e., a signal obtained by receiving reflected light from the subject S). The distance measuring unit 28a 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.

[0122] The specific distance measurement method used in the distance measurement system 40 will be described later.

[0123] The temperature detection unit 49 detects the temperature of the light emitting unit 41. The temperature detection unit 49 performs temperature detection using, for example, a diode.

[0124] In this example, information about the temperature detected by the temperature detection unit 49 is supplied to the drive unit 42, which enables the drive unit 42 to drive the light emitting unit 41 based on the temperature information.

[0125] (Range Measurement Method) The distance measurement method used in the distance measurement system 40 may be, for example, a STL (Structured Light) method or a ToF (Time of Flight) method.

[0126] 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.

[0127] Fig. 18A is an explanatory diagram of the STL method. In the STL method, pattern light Lp having a dot pattern such as that shown in Fig. 18A is irradiated onto a subject S. The pattern light Lp is divided into a plurality of blocks BL, and a different dot pattern is assigned to each block BL (dot patterns are arranged not to overlap between blocks BL).

[0128] FIG. 18B is an explanatory diagram of the distance measurement principle of the STL system.

[0129] 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 drawing schematically represents the angle of view of the light receiving unit 46.

[0130] In addition, "BLn" in the drawing 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 46.

[0131] 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.

[0132] The STL method is a method for determining the shape and depth of the subject S by utilizing the fact that the irradiated pattern is distorted by the object shape of the subject S. Specifically, it is a method for determining the shape and depth of the subject S from the way the pattern is distorted.

[0133] When the STL system is employed, for example, a global shutter type IR (Infrared) light receiving unit 46 is used as the light receiving unit 46. In the case of the STL system, the distance measuring unit 28a controls the drive unit 42 so that the light emitting unit 41 emits pattern light, detects distortion of the pattern in the image signal obtained via the signal processing unit 47, and calculates the distance based on the distortion of the pattern.

[0134] 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 41, reflected by the object, and reaching the light-receiving unit 46.

[0135] When the so-called direct ToF (dToF) method is adopted as the ToF method, a SPAD (Single Photon Avalanche Diode) is used as the light receiving unit 46, and the light emitting unit 41 is pulse-driven. In this case, the distance measuring unit 28a calculates the time difference between light emission and reception of light emitted from the light emitting unit 41 and received by the light receiving unit 46, based on a signal input via the signal processing unit 47, and calculates the distance to each part of the subject S based on the time difference and the speed of light.

[0136] When the so-called indirect ToF (iToF) method (phase difference method) is adopted as the ToF method, the light receiving unit 46 used is, for example, a light receiving unit 46 capable of receiving IR.

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

[0138] FIG. 19 is a block diagram showing a schematic configuration example of a vehicle control system, which is an example of a mobile object control system to which the technology according to the present disclosure can be applied.

[0139] The vehicle control system 12000 includes a plurality of electronic control units connected via a communication network 12001. In the example shown in Fig. 19, the vehicle control system 12000 includes a drive system control unit 12010, a body system control unit 12020, an outside-vehicle information detection unit 12030, an inside-vehicle information detection unit 12040, and an integrated control unit 12050. Also shown as functional components of the integrated control unit 12050 are a microcomputer 12051, an audio / video output unit 12052, and an in-vehicle network I / F (Interface) 12053.

[0140] The drivetrain control unit 12010 controls the operation of devices related to the drivetrain of the vehicle in accordance with various programs. For example, the drivetrain control unit 12010 functions as a control device for a drive force generating device for generating a drive force of the vehicle, such as an internal combustion engine or a drive motor, a drive force transmission mechanism for transmitting the drive force to the wheels, a steering mechanism for adjusting the steering angle of the vehicle, and a braking device for generating a braking force of the vehicle.

[0141] The body system control unit 12020 controls the operation of various devices equipped in the vehicle body according to various programs. For example, the body system control unit 12020 functions as a control device for a keyless entry system, a smart key system, a power window device, or various lamps such as headlamps, backup lamps, brake lamps, turn signals, and fog lamps. In this case, radio waves transmitted from a portable device that serves as a key or signals from various switches can be input to the body system control unit 12020. The body system control unit 12020 receives these radio waves or signals and controls the vehicle's door lock device, power window device, lamps, etc.

[0142] The outside-vehicle information detection unit 12030 detects information outside the vehicle equipped with the vehicle control system 12000. For example, an imaging unit 12031 is connected to the outside-vehicle information detection unit 12030. The outside-vehicle information detection unit 12030 causes the imaging unit 12031 to capture images outside the vehicle and receives the captured images. The outside-vehicle information detection unit 12030 may perform object detection processing or distance detection processing for people, cars, obstacles, signs, characters on the road surface, etc. based on the received images.

[0143] The imaging unit 12031 is an optical sensor that receives light and outputs an electrical signal corresponding to the amount of light received. The imaging unit 12031 can output the electrical signal as an image or as distance measurement information. The light received by the imaging unit 12031 may be visible light or invisible light such as infrared light.

[0144] The in-vehicle information detection unit 12040 detects information inside the vehicle. For example, a driver state detection unit 12041 that detects the state of the driver is connected to the in-vehicle information detection unit 12040. The driver state detection unit 12041 includes, for example, a camera that captures an image of the driver, and the in-vehicle information detection unit 12040 may calculate the degree of fatigue or concentration of the driver based on the detection information input from the driver state detection unit 12041, or may determine whether the driver is dozing off.

[0145] The microcomputer 12051 can calculate control target values ​​for the driving force generating device, steering mechanism, or braking device based on the information inside and outside the vehicle acquired by the outside-vehicle information detection unit 12030 or the inside-vehicle information detection unit 12040, and output control commands to the drive system control unit 12010. For example, the microcomputer 12051 can perform cooperative control aimed at realizing the functions of an ADAS (Advanced Driver Assistance System), including vehicle collision avoidance or impact mitigation, following driving based on the distance between vehicles, maintaining vehicle speed, vehicle collision warning, vehicle lane departure warning, etc.

[0146] In addition, the microcomputer 12051 can perform cooperative control for the purpose of autonomous driving, which allows the vehicle to travel autonomously without relying on driver operation, by controlling the driving force generating device, steering mechanism, braking device, etc. based on information about the surroundings of the vehicle obtained by the outside vehicle information detection unit 12030 or the inside vehicle information detection unit 12040.

[0147] Furthermore, the microcomputer 12051 can output a control command to the body system control unit 12020 based on the information outside the vehicle acquired by the outside information detection unit 12030. For example, the microcomputer 12051 can control the headlamps according to the position of a preceding vehicle or an oncoming vehicle detected by the outside information detection unit 12030, and perform cooperative control aimed at preventing glare, such as switching from high beams to low beams.

[0148] The audio / video output unit 12052 transmits at least one of audio and video output signals to an output device capable of visually or audibly notifying the passengers of the vehicle or the outside of the vehicle of information. In the example of Fig. 19, the output devices are exemplified by an audio speaker 12061, a display unit 12062, and an instrument panel 12063. The display unit 12062 may include, for example, at least one of an on-board display and a head-up display.

[0149] FIG. 20 is a diagram showing an example of the installation position of the imaging unit 12031.

[0150] In FIG. 20, the imaging unit 12031 includes imaging units 12101, 12102, 12103, 12104, and 12105.

[0151] The imaging units 12101, 12102, 12103, 12104, and 12105 are provided, for example, at positions such as the front nose, side mirrors, rear bumper, back door, and the top of the windshield inside the vehicle cabin of the vehicle 12100. The imaging unit 12101 provided on the front nose and the imaging unit 12105 provided on the top of the windshield inside the vehicle cabin mainly acquire images of the front of the vehicle 12100. The imaging units 12102 and 12103 provided on the side mirrors mainly acquire images of the sides of the vehicle 12100. The imaging unit 12104 provided on the rear bumper or back door mainly acquires images of the rear of the vehicle 12100. The imaging unit 12105 provided on the top of the windshield inside the vehicle cabin is mainly used to detect preceding vehicles, pedestrians, obstacles, traffic lights, traffic signs, lanes, etc.

[0152] 20 shows an example of the imaging ranges of the imaging units 12101 to 12104. Imaging range 12111 indicates the imaging range of the imaging unit 12101 provided on the front nose, imaging ranges 12112 and 12113 indicate the imaging ranges of the imaging units 12102 and 12103 provided on the side mirrors, respectively, and imaging range 12114 indicates the imaging range of the imaging unit 12104 provided on the rear bumper or back door. For example, by overlaying the image data captured by the imaging units 12101 to 12104, an overhead image of the vehicle 12100 viewed from above can be obtained.

[0153] At least one of the image capturing units 12101 to 12104 may have a function of acquiring distance information. For example, at least one of the image capturing units 12101 to 12104 may be a stereo camera made up of multiple image capturing elements, or may be an image capturing element having pixels for phase difference detection.

[0154] For example, based on the distance information obtained from the imaging units 12101 to 12104, the microcomputer 12051 can calculate the distance to each three-dimensional object within the imaging ranges 12111 to 12114 and the change in this distance over time (relative speed with respect to the vehicle 12100), thereby extracting as a preceding vehicle, in particular, the three-dimensional object that is the closest three-dimensional object on the path of the vehicle 12100 and traveling in approximately the same direction as the vehicle 12100 at a predetermined speed (e.g., 0 km / h or higher). Furthermore, the microcomputer 12051 can set a vehicle-to-vehicle distance to be maintained in advance in front of the preceding vehicle, and perform automatic braking control (including follow-up stop control), automatic acceleration control (including follow-up start control), etc. In this way, cooperative control can be performed for the purpose of autonomous driving, which allows the vehicle to travel autonomously without relying on driver operation.

[0155] For example, the microcomputer 12051 classifies and extracts three-dimensional object data regarding three-dimensional objects into two-wheeled vehicles, ordinary vehicles, large vehicles, pedestrians, utility poles, and other three-dimensional objects based on distance information obtained from the imaging units 12101 to 12104, and can use the data for automatic obstacle avoidance. For example, the microcomputer 12051 distinguishes obstacles around the vehicle 12100 into obstacles that are visible to the driver of the vehicle 12100 and obstacles that are difficult to see. The microcomputer 12051 then determines a collision risk that indicates the risk of collision with each obstacle, and when the collision risk is equal to or greater than a set value and a collision is possible, the microcomputer 12051 can provide driving assistance for collision avoidance by outputting an alarm to the driver via the audio speaker 12061 or the display unit 12062, or by performing forced deceleration or avoidance steering via the drive system control unit 12010.

[0156] At least one of the image capturing units 12101 to 12104 may be an infrared camera that detects infrared rays. For example, the microcomputer 12051 can recognize a pedestrian by determining whether a pedestrian is present in the images captured by the image capturing units 12101 to 12104. Such pedestrian recognition is performed, for example, by extracting feature points from the images captured by the image capturing units 12101 to 12104 as infrared cameras and performing pattern matching on a series of feature points that indicate the outline of an object to determine whether the object is a pedestrian. When the microcomputer 12051 determines that a pedestrian is present in the images captured by the image capturing units 12101 to 12104 and recognizes the pedestrian, the audio / image output unit 12052 controls the display unit 12062 to superimpose a rectangular outline on the recognized pedestrian for emphasis. The audio / image output unit 12052 may also control the display unit 12062 to display an icon or the like indicating the pedestrian at a desired position.

[0157] The above describes an example of a vehicle control system to which the technology according to the present disclosure can be applied. The technology according to the present disclosure can be applied to the vehicle exterior information detection unit 12030 and the like among the above-described configurations. By applying any of the light-emitting elements 1, 1a, 1b, and 1c according to the first to seventh embodiments to the light-emitting elements of the vehicle exterior information detection unit 12030 and the like, it is possible to accurately measure the distance to an obstacle or the like located around the vehicle.

[0158] The present technology can be configured as follows: (1) A light-emitting device comprising: a first reflective layer and a second reflective layer spaced apart along an optical axis direction; an active layer having a current confinement region disposed between the first reflective layer and the second reflective layer; a first contact layer and a second contact layer spaced apart along the optical axis direction and causing a current to flow through the active layer; and a step portion disposed between the first contact layer and the first reflective layer. (2) The planar shape of the step portion is such that the light intensity of a near-field pattern profile of emitted light is 1 / e ２(3) The light-emitting element according to (1), wherein the active layer has a semiconductor insulating region, and the in-plane position of the semiconductor insulating region has an outer size that surrounds the light beam shape of the emitted light at a position 0.5 μm or more away from the light beam shape when viewed in plan. (4) The light-emitting element according to any one of (1) to (3), wherein the first reflective layer is arranged to cover the side and top surfaces of the step portion and is made of a dielectric material. (5) The light-emitting element according to (4), wherein the step portion has a semiconductor layer whose side and top surfaces are covered by the first reflective layer. (6) The light-emitting element according to (5), wherein the semiconductor layer contains the same semiconductor material as the first contact layer. (7) The light-emitting element according to (5), wherein the semiconductor layer contains a semiconductor material different from that of the first contact layer. (8) The light-emitting device according to any one of (1) to (4), wherein the step portion has a first dielectric layer, and the first reflective layer is arranged so as to cover the side and top surfaces of the first dielectric layer and is composed of a second dielectric layer containing a dielectric material different from the first dielectric layer. (9) The light-emitting device according to any one of (1) to (8), wherein the first reflective layer overlapping with a peripheral portion of a light beam propagating in the optical axis direction reflects light of a different wavelength from the first reflective layer overlapping with a central portion of the light beam. (10) The light-emitting device according to any one of (1) to (8), wherein the peripheral portion of the step portion has a thickness in the optical axis direction different from that of the central portion. (11) The light-emitting device according to (10), wherein the step portion has a semiconductor layer whose thickness in the optical axis direction is different between the central portion and the peripheral portion, and the first reflective layer has a dielectric layer covering a surface of the semiconductor layer. (12) The light-emitting device according to any one of (1) to (11), comprising: a first cladding layer disposed between the first contact layer and the active layer; and a second cladding layer disposed between the second contact layer and the active layer, wherein the first cladding layer has an insulating region that does not allow current to flow from the first contact layer at a location that does not overlap with the step portion in a plan view. (13) The light-emitting device according to (12), comprising: a third reflective layer disposed between the first contact layer and the first cladding layer.(14) The light-emitting element according to (12) or (13), further comprising: dividing insulating regions that divide the first contact layer into a plurality of parts in a plane, the dividing insulating regions having a width in a plane direction that is narrower than the width in a plane direction of the insulating region. (15) The light-emitting element according to (14), further comprising: a plurality of the first reflective layers corresponding to the plurality of first contact layers divided by the dividing insulating regions; and one second reflective layer. (16) The light-emitting device according to any one of (12) to (15), comprising: a tunnel junction layer disposed between two of the active layers adjacent in the optical axis direction, among the plurality of active layers disposed apart from each other in the optical axis direction; and a plurality of the first cladding layers and a plurality of the second cladding layers disposed on both sides of each of the plurality of active layers in the optical axis direction, with each of the plurality of first cladding layers containing p-type impurities and a plurality of the second cladding layers containing n-type impurities, each of the plurality of first cladding layers having the insulating region, and one of the plurality of second cladding layers other than the second cladding layer closest to the second contact layer having the insulating region. (17) The light-emitting device according to any one of (1) to (16), wherein the second reflective layer is disposed between the second contact layer and the active layer. (18) The light-emitting device according to any one of (1) to (16), wherein the second contact layer is disposed between the second reflective layer and the active layer. (19) The light-emitting element according to (18), wherein the second contact layer is disposed inside the second reflective layer.

[0159] The aspects of the present disclosure are not limited to the individual embodiments described above, but include various modifications that may be conceived by those skilled in the art, and the effects of the present disclosure are not limited to the above-described contents. In other words, various additions, modifications, and partial deletions are possible within the scope of the conceptual idea and spirit of the present disclosure, which is derived from the contents defined in the claims and their equivalents.

[0160] 1, 1a, 1b, 1c, 1d, 1e, 1f, 1g, 1h light emitting element, 2 first reflective layer (upper mirror layer), 3 second reflective layer (lower mirror layer), 4 active layer, 4a optical field, 5 first contact layer (upper contact layer), 6 second contact layer (lower contact layer), 7 step portion, 7b center portion, 7c peripheral portion, 8 upper metal layer, 9 lower metal layer, 10, 10a semiconductor layer, 11 first cladding layer (upper cladding layer), 12 second cladding layer (lower cladding layer), 13 GaAs substrate, 15 insulating region, 16 anti-reflection layer, 21 resist film, 22 upper mirror layer (third reflective layer), 23 etching stop layer, 24 dielectric multilayer film (first dielectric multilayer film), 25 dielectric layer (first dielectric multilayer film), 26 resist film, 27 insulating region, 28 resist film, 29 resist film, 31 tunnel junction layer

Claims

1. A light-emitting device comprising: a first reflective layer and a second reflective layer spaced apart along the optical axis; an active layer having a current confinement region disposed between the first reflective layer and the second reflective layer; a first contact layer and a second contact layer spaced apart along the optical axis and configured to pass current through the active layer; and a step portion disposed between the first contact layer and the first reflective layer.

2. The planar shape of the step portion is such that the light intensity of the near-field pattern profile of the emitted light is 1 / e ２ The light-emitting element according to claim 1 , wherein the light-emitting element has a shape similar to the light beam shape defined within the above range.

3. The light-emitting element according to claim 1, wherein the active layer has a semiconductor insulating region, and the in-plane position of the semiconductor insulating region has an outer size that surrounds the light beam shape of the emitted light at a position 0.5 μm or more away from the light beam shape when viewed in a plane.

4. The light-emitting device according to claim 1, wherein the first reflective layer is arranged so as to cover the side and top surfaces of the step portion and is made of a dielectric material.

5. The light-emitting element according to claim 4, wherein the step portion has a semiconductor layer whose side and top surfaces are covered with the first reflective layer.

6. The light-emitting element according to claim 5, wherein the semiconductor layer contains the same semiconductor material as the first contact layer.

7. The light-emitting device according to claim 5, wherein the semiconductor layer comprises a semiconductor material different from that of the first contact layer.

8. The light-emitting element according to claim 1, wherein the step portion has a first dielectric layer, and the first reflective layer is arranged so as to cover the side and top surfaces of the first dielectric layer and is composed of a second dielectric layer containing a dielectric material different from that of the first dielectric layer.

9. The light-emitting element according to claim 1, wherein the first reflective layer overlapping the peripheral portion of the light beam propagating in the optical axis direction reflects light of a different wavelength than the first reflective layer overlapping the central portion of the light beam.

10. The light-emitting device according to claim 1, wherein the peripheral portion of the step portion has a thickness in the optical axis direction that is different from that of the central portion.

11. The light-emitting element according to claim 10, wherein the step portion has a semiconductor layer whose thickness in the optical axis direction differs between the central portion and the peripheral portion, and the first reflective layer has a dielectric layer covering the surface of the semiconductor layer.

12. A light-emitting element as described in claim 1, comprising: a first cladding layer disposed between the first contact layer and the active layer; and a second cladding layer disposed between the second contact layer and the active layer, wherein the first cladding layer has an insulating region that does not allow current to flow from the first contact layer in a location that does not overlap with the step portion when viewed in a plane.

13. The light-emitting device according to claim 12, further comprising a third reflective layer disposed between the first contact layer and the first cladding layer.

14. The light-emitting element according to claim 12, further comprising divided insulating regions that divide the first contact layer into a plurality of regions in a plane, the width of the divided insulating regions in the plane direction being narrower than the width of the insulating region in the plane direction.

15. The light-emitting element according to claim 14, wherein a plurality of the first reflective layers and one second reflective layer are provided corresponding to a plurality of the first contact layers divided by the dividing insulating regions.

16. A light-emitting device as described in claim 12, comprising: a tunnel junction layer disposed between two of the active layers adjacent in the optical axis direction, among the plurality of active layers disposed at a distance from each other in the optical axis direction; and a plurality of first cladding layers and a plurality of second cladding layers disposed on both sides of each of the plurality of active layers in the optical axis direction, with each of the plurality of first cladding layers containing p-type impurities and a plurality of second cladding layers containing n-type impurities, each of the plurality of first cladding layers having the insulating region; and of the plurality of second cladding layers, the second cladding layers other than the second cladding layer closest to the second contact layer have the insulating region.

17. The light-emitting device according to claim 1, wherein the second reflective layer is disposed between the second contact layer and the active layer.

18. The light-emitting device according to claim 1, wherein the second contact layer is disposed between the second reflective layer and the active layer.

19. The light-emitting device according to claim 18, wherein the second contact layer is disposed inside the second reflective layer.

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