WO2024101079A1

WO2024101079A1 - Light emitting element, light emitting element array and electronic device

Info

Publication number: WO2024101079A1
Application number: PCT/JP2023/037378
Authority: WO
Inventors: 秀輝渡邊; 康貴比嘉; 倫太郎幸田; 敬錫宋; 達也真藤; 修平山口
Original assignee: ソニーグループ株式会社
Priority date: 2022-11-10
Filing date: 2023-10-16
Publication date: 2024-05-16

Abstract

The present invention reduces the influence of temperature changes.　The present technology provides a light emitting element which is provided with at least two active layers that each have a quantum nanostructure, wherein the wavelengths of light produced by the at least two active layers are different from each other. The quantum nanostructure may comprise one structure that is selected from the group consisting of a quantum well structure, a quantum wire, and a quantum dot. The forms of the quantum nanostructures contained in the at least two active layers may be different from each other. The lengths in the optical axis direction of the quantum wells contained in the at least two active layers may be different from each other.

Description

Light-emitting element, light-emitting element array, and electronic device

The technology disclosed herein (hereinafter also referred to as "the technology") relates to a light-emitting device, a light-emitting device array, and a method for manufacturing a light-emitting device.

In recent years, in the field of light-emitting devices such as edge-emitting lasers, there has been a trend toward light-emitting devices in which multiple light-generating active layers are stacked via tunnel junctions or the like. Such light-emitting devices are called multi-junction type light-emitting devices.

For example, Patent Document 1 discloses a "laser element characterized by the inclusion of a tunnel junction."

JP 2006-190976 A

However, it is known that the intensity of the light generated by this active layer is affected by temperature changes around the active layer. In order to output stable light, it is preferable that the characteristics of the active layer are not affected by temperature changes.

The primary objective of this technology is to provide a light-emitting element, a light-emitting element array, and an electronic device that reduce the effects of temperature changes.

This technology is
at least two active layers including quantum nanostructures;
The light emitting device is provided in which the at least two active layers generate light having wavelengths different from each other.
The quantum nanostructure may include any one selected from the group consisting of a quantum well structure, a quantum wire, and a quantum dot.
The quantum nanostructures included in at least two of the active layers may have different shapes.
The quantum wells included in at least two of the active layers may have different lengths in the optical axis direction.
The quantum nanostructures contained in at least two of the active layers may have different compositions.
The shapes of the quantum dots contained in at least two of the active layers may be different from each other in a direction perpendicular to the optical axis direction.
The active layer has a structure in which the quantum nanostructure and a barrier layer are stacked on each other,
The barrier layers included in at least two of the active layers may have different shapes.
The active layer has a structure in which the quantum nanostructure and a barrier layer are stacked on each other,
The barrier layers included in at least two of the active layers may have different compositions.
The active layer has a structure in which the quantum nanostructure and a barrier layer are stacked on each other,
The barrier layers included in at least two of the active layers may be doped with impurities at different concentrations.
The active layer may have a structure in which the quantum nanostructure and a barrier layer are stacked on top of each other, and at least two of the active layers may have different doping profiles of impurities doped into the barrier layers.
a first compound semiconductor layer having a first conductivity type, a second compound semiconductor layer having a second conductivity type, and the active layer are laminated in this order;
The first compound semiconductor layer and the second compound semiconductor layer may be tunnel junctioned to each other.
a first compound semiconductor layer having a first conductivity type, a second compound semiconductor layer having a second conductivity type, and the active layer are laminated in this order;
The first compound semiconductor layer and the second compound semiconductor layer may be wafer-bonded to each other.
a first compound semiconductor layer having a first conductivity type, a second compound semiconductor layer having a second conductivity type, and the active layer are laminated in this order;
The first compound semiconductor layer and the second compound semiconductor layer may be tunnel-junctioned and wafer-bonded to each other.
The active layer may be configured such that the higher the light intensity the longer the photoluminescence wavelength.
The light emitting element may be an edge emitting laser.
The light emitting element may be a surface emitting laser.
In addition, the present technology provides a light-emitting element having a plurality of light-emitting elements arranged two-dimensionally in a plan view,
The present invention provides a light-emitting element array, in which the quantum nanostructures included in the active layers of at least two of the light-emitting elements have shapes different from each other.
In addition, the present technology provides a light-emitting element having a plurality of light-emitting elements arranged two-dimensionally in a plan view,
The present invention provides a light-emitting element array, in which the quantum nanostructures contained in the active layers of at least two of the light-emitting elements have compositions different from each other.
The present technology also provides an electronic device including the light-emitting element.

This technology can provide a light-emitting element, a light-emitting element array, and an electronic device that reduce the effects of temperature changes. Note that the effects described here are not necessarily limited to those described herein, and may be any of the effects described in this disclosure.

11 is a graph showing an example of a correlation between the temperature of a case in which a light-emitting element is mounted and the rate of change in characteristics of the light-emitting element. 1 is a cross-sectional view showing a configuration example of a light-emitting device 100 according to an embodiment of the present technology. 1 is an energy band diagram illustrating the principle of a light-emitting device 100 according to an embodiment of the present technology. 1 is an energy band diagram illustrating the principle of a light-emitting device 100 according to an embodiment of the present technology. 1 is an energy band diagram illustrating the principle of a light-emitting device 100 according to an embodiment of the present technology. 1 is a cross-sectional view showing a configuration example of a light-emitting device 100 according to an embodiment of the present technology. 4 is a flowchart showing an example of a method for manufacturing the light-emitting device 100 according to an embodiment of the present technology. 1 is a perspective view showing a configuration example of a light-emitting element array 200 according to an embodiment of the present technology. 1 is a block diagram showing a schematic configuration example of a distance measurement device (range-finding device) 1000 including a surface-emitting laser (light-emitting element) 100 according to an embodiment of the present technology. 1 is a block diagram showing a schematic configuration example of a vehicle control system that is an example of a mobile object control system to which the present technology can be applied. 1A to 1C are diagrams illustrating examples of installation positions of a distance measuring device 12031 according to an embodiment of the present technology.

Below, a preferred embodiment for implementing the present technology will be described with reference to the drawings. Note that the embodiment described below is an example of a representative embodiment of the present technology, and does not limit the scope of the present technology. In addition, the present technology can be combined with any of the following examples and their variations.

In the following description of the embodiments, configurations may be described using terms that include "approximately", such as "approximately parallel" and "approximately perpendicular". For example, "approximately parallel" does not only mean completely parallel, but also means that it is substantially parallel, that is, it includes a state that is deviated from a completely parallel state by, for example, about a few percent. The same applies to other terms that include "approximately". In addition, each figure is a schematic diagram, and is not necessarily an accurate depiction. The scale of the drawings has been exaggerated to make the characteristics of the technology easier to understand. Therefore, it should be noted that the scale of the drawings and the scale of the actual device are not necessarily the same.

Unless otherwise specified, in the drawings, "top" means the upper direction or upper side in the drawing, "bottom" means the lower direction or lower side in the drawing, "left" means the left direction or left side in the drawing, and "right" means the right direction or right side in the drawing. In addition, in the drawings, the same or equivalent elements or members are given the same reference numerals, and duplicate explanations are omitted.

The explanation will be given in the following order.
1. First embodiment of the present technology (example 1 of light-emitting device)
2. Second embodiment of the present technology (example 2 of light-emitting device)
3. Third embodiment of the present technology (example 3 of light-emitting device)
4. Fourth embodiment of the present technology (light-emitting device example 4)
5. Fifth embodiment of the present technology (example 5 of light-emitting device)
6. Sixth embodiment of the present technology (example of light-emitting element array)
7. Seventh embodiment of the present technology (example 1 of electronic device)
8. Eighth embodiment of the present technology (electronic device example 2)

[1. First embodiment of the present technology (example 1 of light-emitting device)]
[(1) Overview]
Conventionally, light emitting devices such as edge emitting lasers (EELs) and vertical cavity surface emitting lasers (VCSELs) include an active layer that generates light. It is known that the intensity of the light generated by the active layer is affected by temperature changes around the active layer.

This will be explained with reference to Figure 1. Figure 1 is a graph showing an example of the correlation between the temperature of the case in which the light-emitting element is mounted and the rate of change in the characteristics of the light-emitting element when driven at a constant voltage. I indicates the value of the current flowing through the light-emitting element. L indicates the intensity of light generated by the light-emitting element. This graph shows the characteristics of a surface-emitting laser with a peak wavelength of the resonance spectrum of 940 nm and a gain peak wavelength of 925 nm for the active layer. In this example, due to self-heating caused by driving the surface-emitting laser and temperature changes in the case, when the case temperature is near 70 degrees, the wavelength of the resonance spectrum and the gain peak wavelength match. Therefore, as shown in Figure 1, when the case temperature is near 70 degrees, the intensity L of the generated light changes to 121%, becoming the highest.

On the other hand, when the case temperature was higher than 70 degrees and when the case temperature was lower than 70 degrees, the intensity L of the generated light was low. In order to output light stably, it is not desirable to be affected by temperature changes in this way.

The present technology provides a light-emitting device that has at least two active layers including a quantum nanostructure, and the wavelengths of light generated by the at least two active layers are different from each other.

An example of the configuration of a light-emitting device according to an embodiment of the present technology will be described with reference to FIG. 2. FIG. 2 is a cross-sectional view showing an example of the configuration of a light-emitting device 100 according to an embodiment of the present technology. The light-emitting device 100 according to an embodiment of the present technology can be, for example, an edge-emitting laser (EEL: Edge Emitting Laser) or a surface-emitting laser (VCSEL: Vertical Cavity Surface Emitting Laser).

As shown in FIG. 2, the light-emitting element 100 has at least two active layers that generate light. In this configuration example, the light-emitting element 100 has three active layers 30A, 30B, and 30C. To explain in more detail, the light-emitting element 100 has a second cladding layer 21 having a second conductivity type, an active layer 30A, a first compound semiconductor layer 10A having a first conductivity type, a second compound semiconductor layer 20A having a second conductivity type, an active layer 30B, a first compound semiconductor layer 10B having a first conductivity type, a second compound semiconductor layer 20B having a second conductivity type, an active layer 30C, and a first cladding layer 11 having a first conductivity type stacked in this order.

Although not shown in the figure, the first cladding layer 11 is laminated on a substrate. Examples of this substrate include a sapphire substrate, a GaAs substrate, a GaN substrate, a SiC substrate, an alumina substrate, a ZnS substrate, a ZnO substrate, an AlN substrate, a LiMgO substrate, a LiGaO2 substrate, a MgAl2O4 substrate, an InP substrate, a Si substrate, and substrates having a base layer or a buffer layer formed on the surface (main surface) of these substrates.

The first conductivity type may be n-type, and the second conductivity type may be p-type. Alternatively, the first conductivity type may be p-type, and the second conductivity type may be n-type. Examples of n-type impurities include silicon (Si), selenium (Se), and tellurium (Te). Examples of p-type impurities include zinc (Zn), magnesium (Mg), beryllium (Be), and carbon (C).

Each of the first compound semiconductor layer 10 (10A, 10B) and the second compound semiconductor layer 20 (20A, 20B) may be a layer having a single structure, a multilayer structure, or a superlattice structure. Furthermore, each of the first compound semiconductor layer 10 and the second compound semiconductor layer 20 may be a layer having a composition gradient layer or a concentration gradient layer.

The first compound semiconductor layer 10 and the second compound semiconductor layer 20 may be formed, for example, by metal-organic chemical vapor deposition (MOCVD, MOVPE), molecular beam epitaxy (MBE), hydride vapor phase epitaxy (HVPE), atomic layer deposition (ALD), migration enhanced epitaxy (MEE), plasma-assisted physical vapor deposition (PPD), etc., but are not limited to these.

When the MOCVD method is used, for example, trimethylgallium (( _CH3 ) _3Ga ) is used as the source gas for gallium. For example, trimethylaluminum (( _CH3 ) _3Al ) is used as the source gas for aluminum. For example, trimethylindium (( _CH3 ) _3In ) is used as the source gas for indium. For example, trimethylarsenic (( _CH3 ) _3As ) is used as the source gas for As. For example, monosilane ( _SiH4 ) is used as the source gas for silicon. For example, carbon tetrabromide ( _CBr4 ) or _{diethyltellurium} ( _C4H10Te ) is used as the source gas for carbon.

Although not shown, the light emitting device 100 may include a first DBR layer and a second DBR layer. Each of the first DBR layer and the second DBR layer may be composed of, for example, a semiconductor multilayer film or a dielectric multilayer film. Examples of the dielectric material include oxides, nitrides (e.g., SiN _x , AlN x , AlGaN _x , GaN _x , BN _x , etc.) and fluorides of Si, Mg, Al, Hf, Nb, Zr, Sc, Ta, Ga, Zn, Y, B, _Ti , etc. Specifically, the dielectric material may be SiO _x , TiO _x , NbO _x , ZrO _x , TaO _x , ZnO _x , AlO _x , HfO _x , SiN _x , AlN _x , etc. The light reflecting layer can be formed by alternately stacking two or more types of dielectric films made of dielectric materials having different refractive indices among these dielectric materials. Each of the first DBR layer and the second DBR layer may be a multilayer film such as _SiOx / _SiNy , _SiOx / _TaOy , _SiOx / _NbOy , _SiOx / _ZrOy , or _SiOx / _AlNy .

The number of layers in each of the first DBR layer and the second DBR layer can be 2 or more, preferably 5 to 50. The length in the optical axis direction of each of the first DBR layer and the second DBR layer can be, for example, 0.6 μm to 5.0 μm. The optical reflectance of each of the first DBR layer and the second DBR layer is 95% or more, preferably 99% or more. In order to obtain the desired optical reflectance, the material, film thickness, number of layers, etc. constituting each dielectric film are appropriately selected. The thickness of each dielectric film is appropriately adjusted depending on the material used, etc.

The first DBR layer and the second DBR layer, which are made of a dielectric multilayer film, can each be formed based on a known method. For example, PVD methods such as vacuum deposition, sputtering, reactive sputtering, ECR plasma sputtering, magnetron sputtering, ion beam assisted deposition, ion plating, and laser ablation; various CVD methods; coating methods such as spraying, spin coating, and dipping; a method combining two or more of these methods; a method combining these methods with one or more of the following: full or partial pretreatment, irradiation with inert gas (Ar, He, Xe, etc.) or plasma, irradiation with oxygen gas, ozone gas, plasma, oxidation treatment (heat treatment), and exposure treatment.

As shown in Fig. 2, a first compound semiconductor layer 10 having a first conductivity type, a second compound semiconductor layer 20 having a second conductivity type, and an active layer 30 are laminated in this order. At this time, it is preferable that the first compound semiconductor layer 10 and the second compound semiconductor layer 20 are tunnel junctioned with each other. As a result, when a reverse bias voltage is applied to each of the first compound semiconductor layer 10 and the second compound semiconductor layer 20, a current flows due to the tunnel effect. In order to reduce the voltage drop at the interface between the first compound semiconductor layer 10 and the second compound semiconductor layer 20 and to flow a current with high efficiency, the concentration of the impurity doped into each of the first compound semiconductor layer 10 and the second compound semiconductor layer 20 is 1 x ¹⁰¹⁸ /cm3 ^or more, preferably 1 x ¹⁰¹⁹ / ^cm3 .

[(2) Active Layer]
In this case, it is preferable that the wavelengths of the light generated by at least two active layers are different from each other. In this configuration example, the three active layers 30A, 30B, and 30C may each generate a different wavelength of light. Alternatively, the wavelengths of the light generated by the two active layers 30A and 30B may be different from each other, and the wavelength of the light generated by the remaining active layer 30C may be approximately the same as the wavelength of the light generated by one of the other two active layers 30A and 30B. This can reduce the effects of temperature changes.

　Conventional multi-junction light-emitting elements are generally designed so that the wavelengths of light generated by each active layer are roughly the same. This creates the problem that temperature changes affect the characteristics of each active layer in the same way.

On the other hand, in the light-emitting device 100 according to an embodiment of the present technology, the wavelengths of light generated by at least two active layers are different from each other. Therefore, even if one active layer is affected by a change in temperature, the other active layer may not be affected as much. The active layers complement each other, and the light-emitting device 100 as a whole can reduce the effects of temperature changes. As a result, the light-emitting device 100 according to an embodiment of the present technology can maintain high light-emitting intensity and gain over a wide temperature range.

The wavelength λ of light and the energy E of light are related by the following equation (1). Note that h is Planck's constant, v is the frequency of light, and c is the speed of light.

E = hv = hc/λ ... (1)

Therefore, by making the band gap energies of at least two active layers different from each other, the wavelengths of light generated by these two active layers can be made different from each other. This band gap energy will be described with reference to FIG. 3. FIG. 3 is an energy band diagram explaining the principle of the light-emitting device 100 according to one embodiment of the present technology. As shown in FIG. 3, the active layers 30A, 30B, and 30C each have a different energy band shape. As a result, the active layers 30A, 30B, and 30C each generate a different wavelength of light.

Each of the active layers 30A, 30B, and 30C may include a quantum nanostructure. The quantum nanostructure may include any one selected from the group consisting of a quantum well structure, a quantum wire, and a quantum dot.

Each of the active layers 30A, 30B, and 30C may include a quantum well structure, such as a single quantum well structure (SQW structure) or a multiple quantum well structure (MQW structure). The active layer including the quantum well structure has a structure in which at least one quantum well layer and a barrier layer are stacked on top of each other. Combinations of compound semiconductors constituting the quantum well layer and the barrier layer include, for example, In _y Ga _(1-y) As and GaAs, In _y Ga _(1-y) As and In _z Ga _(1-z) As [where y>z], or In _y Ga _(1-y) As and AlGaAs.

When the active layer includes a quantum well structure, the active layer may be a multiple quantum well structure in which a quantum well layer made of InGaAs and having a length in the optical axis direction of 3.0 to 10.0 nm and a barrier layer made of AlGaAs and having a length in the optical axis direction of 4.0 to 15.0 nm are stacked on top of each other.

In this case, it is preferable that the shapes of the quantum nanostructures contained in at least two active layers are different from each other. In this configuration example, the shapes of the quantum nanostructures contained in each of the three active layers 30A, 30B, and 30C may be different. Alternatively, the shapes of the quantum nanostructures contained in the two active layers 30A and 30B may be different from each other, and the shape of the quantum nanostructure contained in the remaining active layer 30C may be approximately the same as the quantum nanostructure contained in one of the other two active layers 30A and 30B.

In particular, in this configuration example, each of the active layers 30A, 30B, and 30C includes a quantum well structure. Therefore, it is preferable that the lengths in the optical axis direction of the quantum well layers included in at least two active layers are different from each other. In this configuration example, the lengths in the optical axis direction of the quantum well layers 31A, 31B, and 31C included in each of the active layers 30A, 30B, and 30C are different from each other. The wavelength of light generated by the quantum well layer is determined by the quantum level formed in the quantum well layer. According to the Schrödinger equation, the quantum level formed in the quantum well layer is determined by the length in the optical axis direction of the quantum well layer. Therefore, the wavelengths of light generated by the active layers 30A, 30B, and 30C are different due to the different lengths in the optical axis direction of the quantum well layers.

The energy band diagram shown in FIG. 3 is an energy band diagram when the active layer includes a quantum well structure. As shown in FIG. 3, the length in the optical axis direction of the quantum well layer 31C included in the active layer 30C on the substrate side (left side of the diagram) is the shortest, and the length in the optical axis direction of the quantum well layer 31A included in the active layer 30A on the light emission side (right side of the diagram) is the longest. For example, the length in the optical axis direction of the quantum well layer can be adjusted so that the wavelength of light generated by the active layer 30C on the substrate side is 915 nm, the wavelength of light generated by the intermediate active layer 30B is 920 nm, and the wavelength of light generated by the active layer 30A on the light emission side is 925 nm.

Furthermore, each of the active layers 30A, 30B, and 30C has a structure in which quantum nanostructures and barrier layers are stacked on top of each other. In this configuration example, each of the active layers 30A, 30B, and 30C has a structure in which quantum well layers 31A, 31B, and 31C and barrier layers 32A, 32B, and 32C are stacked on top of each other. According to the Schrödinger equation, the quantum level formed in the quantum well layer is determined by the shape of the barrier layer. Therefore, by having the barrier layers of at least two active layers have different shapes, the wavelengths of light generated by each of the active layers 30A, 30B, and 30C may be different.

Traditionally, the band gap energy of a quantum well layer is affected by the surrounding temperature. As a result, the wavelength of the light generated by the active layer changes with temperature. Furthermore, it is known that the intensity of the light decreases due to the spread of the carrier distribution within the quantum well layer and the deviation of carriers from the quantum well layer.

According to this technology, each of the active layers 30A, 30B, and 30C has a different resonance spectrum peak wavelength and gain peak wavelength. Therefore, the emission band and gain band of the light-emitting device 100 as a whole are widened. As a result, the effects of temperature changes can be reduced.

In this configuration example, the quantum well layer 31C included in the active layer 30C on the substrate side has the shortest length in the optical axis direction, and the quantum well layer 31A included in the active layer 30A on the light emission side has the longest length in the optical axis direction, but this configuration is not limited to this. For example, the quantum well layer 31C included in the active layer 30C on the substrate side may have the longest length in the optical axis direction, and the quantum well layer 31A included in the active layer 30A on the light emission side may have the shortest length in the optical axis direction. Furthermore, for example, the quantum well layer 31B included in the intermediate active layer 30B may have the shortest length in the optical axis direction.

The length of each quantum well layer 31A, 31B, 31C in the optical axis direction is preferably designed so that the higher the optical intensity of the mode formed in the quantum well layer, the longer the photoluminescence wavelength. This also applies to the other embodiments described below.

The above describes an embodiment in which the active layer includes a quantum well structure. As described above, the quantum nanostructure includes any one selected from the group consisting of a quantum well structure, a quantum wire, and a quantum dot. Therefore, the active layer may include a quantum wire and/or a quantum dot. In other words, the shapes and/or sizes of the quantum wires included in at least two active layers may be different from each other, and the shapes and/or sizes of the quantum dots included in at least two active layers may be different from each other.

Furthermore, for example, active layer 30A may include a quantum well structure, active layer 30B may include quantum wires, and active layer 30C may include quantum dots.

When the active layers are configured to include quantum dots, the shapes of the quantum dots included in at least two active layers may differ from each other in a direction perpendicular to the optical axis direction. In other words, when the light-emitting device 100 is viewed in plan from the second cladding layer 21 side, the shapes of the quantum dots included in each of the active layers 30A, 30B, and 30C may differ from each other in two dimensions.

The above description of the light-emitting element according to the first embodiment of the present technology can be applied to other embodiments of the present technology, unless there is a particular technical contradiction.

[2. Second embodiment of the present technology (example 2 of light-emitting element)]
In the light-emitting device according to an embodiment of the present technology, the compositions of the quantum nanostructures contained in at least two active layers may be different from each other. This will be described with reference to FIG. 4. FIG. 4 is an energy band diagram illustrating the principle of the light-emitting device 100 according to an embodiment of the present technology. As shown in FIG. 4, the active layers 30A, 30B, and 30C have different energy band shapes. As a result, the wavelengths of light generated by the active layers 30A, 30B, and 30C are different.

In particular, in this configuration example, the active layer includes a quantum well structure. Therefore, it is preferable that the compositions of the quantum well layers included in at least two active layers are different from each other. In this configuration example, the compositions of the quantum well layers 31A, 31B, and 31C included in each active layer 30A, 30B, and 30C are different from each other. The wavelength of light generated by the quantum well layer is determined by the quantum level formed in the quantum well layer. Therefore, due to the different compositions of the quantum well layers, the wavelengths of light generated by each active layer 30A, 30B, and 30C are different.

In this configuration example, the quantum well layer contains InGaAs. The quantum well layer 31C contained in the active layer 30C on the substrate side (left side of the figure) has the lowest In composition, and the quantum well layer 31A contained in the active layer 30A on the light emission side (right side of the figure) has the highest In composition. For example, the composition of the quantum well layer can be adjusted so that the wavelength of light generated by the active layer 30C on the substrate side is 915 nm, the wavelength of light generated by the intermediate active layer 30B is 920 nm, and the wavelength of light generated by the active layer 30A on the light emission side is 925 nm.

The above describes an embodiment in which the active layer includes a quantum well structure. As described above, the quantum nanostructure includes any one selected from the group consisting of a quantum well structure, a quantum wire, and a quantum dot. Therefore, the active layer may include a quantum wire and/or a quantum dot. In other words, the quantum wires included in at least two active layers may have different compositions, and the quantum dots included in at least two active layers may have different compositions.

The above description of the light-emitting element according to the second embodiment of the present technology can be applied to other embodiments of the present technology, unless there is a particular technical contradiction.

[3. Third embodiment of the present technology (example 3 of light-emitting device)]
The active layer has a structure in which a quantum nanostructure and a barrier layer are stacked on top of each other. According to the Schrodinger equation, the quantum level formed in the active layer is determined by the composition of the barrier layer. Therefore, the wavelengths of light generated by each active layer may be different by having the barrier layers of different compositions included in at least two active layers.

This will be explained with reference to FIG. 5. FIG. 5 is an energy band diagram illustrating the principle of the light-emitting device 100 according to one embodiment of the present technology. As shown in FIG. 5, the active layers 30A, 30B, and 30C have different energy band shapes. As a result, the active layers 30A, 30B, and 30C generate different wavelengths of light.

In particular, in this configuration example, each of the active layers 30A, 30B, and 30C includes a quantum well structure. Therefore, it is preferable that the compositions of the barrier layers included in at least two active layers are different from each other. In this configuration example, the compositions of the barrier layers 32A, 32B, and 302 included in each of the active layers 30A, 30B, and 30C are different from each other. The wavelength of light generated by the quantum well layer is determined by the quantum level formed in the quantum well layer. Therefore, because the compositions of the barrier layers 32A, 32B, and 32C are different, the wavelength of light generated by each of the active layers 30A, 30B, and 30C is different.

In this configuration example, the quantum well layer contains InGaAs, and the barrier layer contains AlGaAs. The Al composition of the barrier layer 32C contained in the active layer 30C on the substrate side (left side of the figure) is the highest, and the Al composition of the barrier layer 32A contained in the active layer 30A on the light emission side (right side of the figure) is the lowest. For example, the compositions of the barrier layers 32A, 32B, and 32C can be adjusted so that the wavelength of light generated by the active layer 30C on the substrate side is 915 nm, the wavelength of light generated by the intermediate active layer 30B is 920 nm, and the wavelength of light generated by the active layer 30A on the light emission side is 925 nm.

Each of the active layers 30A, 30B, and 30C may include a strained quantum well. The lattice constants of the quantum well layer and the barrier layer may be made different by making the composition of the barrier layer different. This reduces the band gap energy of the quantum well layer in which compressive strain occurs. Also, the band gap energy of the quantum well layer in which tensile strain occurs increases.

The above describes an embodiment in which the active layer includes a quantum well structure. As described above, the quantum nanostructure includes any one selected from the group consisting of a quantum well structure, a quantum wire, and a quantum dot. Therefore, the active layer may be configured to include a quantum wire and/or a quantum dot.

The above description of the light-emitting element according to the third embodiment of the present technology can be applied to other embodiments of the present technology, unless there is a particular technical contradiction.

[4. Fourth embodiment of the present technology (light-emitting device example 4)]
The active layer has a structure in which a quantum nanostructure and a barrier layer are stacked on top of each other. According to the Schrodinger equation, the quantum level formed in the active layer is determined by the band shape when an electric field is applied to the semiconductor. Therefore, the wavelengths of light generated by each active layer may be different by doping the barrier layers of at least two active layers with different concentrations of impurities.

This will be explained again with reference to FIG. 5. As shown in FIG. 5, the active layers 30A, 30B, and 30C have different energy band shapes. This results in the wavelengths of light generated by the active layers 30A, 30B, and 30C being different.

In particular, in this configuration example, the active layer includes a quantum well structure. Therefore, it is preferable that the concentrations of impurities doped into the barrier layers included in at least two active layers are different from each other. In this configuration example, the concentrations of impurities doped into the barrier layers 32A, 32B, and 32C included in each active layer 30A, 30B, and 30C are different from each other. The wavelength of light generated by the quantum well layer is determined by the quantum level formed in the quantum well layer. Therefore, the wavelength of light generated by each active layer 30A, 30B, and 30C is different due to the different concentrations of impurities doped into each barrier layer 32A, 32B, and 32C.

In this configuration example, the quantum well layer contains InGaAs, and the barrier layer contains AlGaAs. The barrier layer 32C included in the active layer 30C on the substrate side (left side of the figure) has the highest impurity concentration, and the barrier layer 32A included in the active layer 30A on the light emission side (right side of the figure) has the lowest impurity concentration. The impurity may be, for example, an ion such as As or P. For example, the impurity concentration doped into each of the barrier layers 32A, 32B, and 32C can be adjusted so that the active layer 30C on the substrate side generates light with a wavelength of 915 nm, the intermediate active layer 30B generates light with a wavelength of 920 nm, and the active layer 30A on the light emission side generates light with a wavelength of 925 nm.

Furthermore, the doping profiles of the impurities doped into the barrier layers included in at least two active layers may be different from each other. The doping profile is the distribution of the impurity concentration from the surface to the depth direction. Even if the concentrations of the impurities doped into each of the barrier layers 32A, 32B, and 32C are the same, by making the doping profiles of the impurities different, it is possible to make the wavelengths of the light generated by each of the active layers 30A, 30B, and 30C different.

The above description of the light-emitting element according to the fourth embodiment of the present technology can be applied to other embodiments of the present technology, unless there is a particular technical contradiction.

[5. Fifth embodiment of the present technology (light-emitting device example 5)]
In the first to fourth embodiments, the first compound semiconductor layer 10 and the second compound semiconductor layer 20 are mutually tunnel-junctioned. When a reverse bias voltage is applied to each of the first compound semiconductor layer 10 and the second compound semiconductor layer 20, the impurity doping concentration of each of the first compound semiconductor layer 10 and the second compound semiconductor layer 20 is 1×10 18 /cm 3 or more, preferably 1× ^{10 19} ^/ cm ³ , in order to reduce the voltage drop at the interface between the first compound semiconductor layer 10 and the second compound semiconductor layer ²⁰ and to allow a current to flow with high efficiency.

On the other hand, as another method for reducing the voltage drop at the interface between the first compound semiconductor layer 10 and the second compound semiconductor layer 20, the first compound semiconductor layer 10 and the second compound semiconductor layer 20 may be wafer-bonded to each other. The wafer bonding may be, for example, plasma activated bonding or surface activated bonding.

This will be explained with reference to FIG. 6. FIG. 6 is a cross-sectional view showing an example configuration of a light-emitting device 100 according to an embodiment of the present technology. This example configuration is generally the same as the example configuration shown in FIG. 2, but differs from the example configuration shown in FIG. 2 in that a bonding layer 40 is laminated between the first compound semiconductor layer 10 and the second compound semiconductor layer 20.

The bonding layer 40 preferably has a low band gap energy and is highly doped with impurities. The bonding layer 40 may contain, for example, InGaAs. With this, when a forward bias voltage is applied to the first cladding layer 11 and the second cladding layer 21, a current can be passed with high efficiency due to the tunnel effect. As a result, the voltage drop at the interface between the first compound semiconductor layer 10 and the second compound semiconductor layer 20 can be reduced.

An example of a method for manufacturing the light-emitting device 100 of the present embodiment will be described with reference to Fig. 7. Fig. 7 is a flowchart showing an example of a method for manufacturing the light-emitting device 100 according to an embodiment of the present technology.

First, in step S1, a first cladding layer 11 having a first conductivity type, an active layer 30B, and a second compound semiconductor layer 20 having a second conductivity type are laminated on a first substrate (not shown in FIG. 6) in this order from the first substrate side.

Next, in step S2, a second cladding layer 21 having a second conductivity type, an active layer 30A, and a first compound semiconductor layer 10 having a first conductivity type are laminated in this order from the second substrate side on a second substrate (not shown in FIG. 6) different from the above substrate.

Next, in step S3, the surfaces of the second compound semiconductor layer 20 stacked on the first substrate and the first compound semiconductor layer 10 stacked on the second substrate are activated. Specifically, for example, natural oxide films and contaminations present on the surfaces are physically removed by an ion beam in a high vacuum state.

Next, in step S4, the surface of the second compound semiconductor layer 20 laminated on the first substrate and the surface of the first compound semiconductor layer 10 laminated on the second substrate are brought into contact and pressed together with a predetermined pressure. This forms a bonding layer 40, and the wafers are bonded.

Finally, in step S5, the second substrate is removed.

As shown in FIG. 6, in this configuration example, the light-emitting device 100 has two active layers 30, but by repeating the above process, it may have three or more active layers 30.

In addition, in the first to fourth embodiments, the first compound semiconductor layer 10 and the second compound semiconductor layer 20 are tunnel-junctioned to each other. The tunnel-junctioned first compound semiconductor layer 10 and second compound semiconductor layer 20 may be wafer-bonded to each other using the above-mentioned process. In other words, the first compound semiconductor layer 10 and the second compound semiconductor layer 20 may be tunnel-junctioned and wafer-bonded to each other.

The above description of the light-emitting element according to the fifth embodiment of the present technology can be applied to other embodiments of the present technology, unless there is a particular technical contradiction.

[6. Sixth embodiment of the present technology (example of light-emitting element array)]
The present technology provides a light-emitting element array in which a plurality of light-emitting elements 100 according to any one of the first to fifth embodiments are arranged two-dimensionally in a plan view, and the shapes of the quantum nanostructures included in the active layers of at least two of the light-emitting elements are different from each other. This will be described with reference to Fig. 8. Fig. 8 is a perspective view showing a configuration example of a light-emitting element array 200 according to an embodiment of the present technology.

As shown in FIG. 8, a plurality of light-emitting elements 100 according to any one of the first to fifth embodiments are arranged two-dimensionally in a planar view. In this case, it is preferable that the shapes of the quantum nanostructures contained in the active layers of at least two of the light-emitting elements 100 are different from each other. In addition, the compositions of the quantum nanostructures contained in the active layers of at least two of the light-emitting elements 100 may be different from each other.

When the light-emitting elements 100 are arranged two-dimensionally as in this figure, the center of the light-emitting element array 200 tends to be hotter, and the ends of the light-emitting element array 200 tend to be colder. Such non-uniformity in temperature and current can lead to failure of the light-emitting elements 100. To ensure non-uniformity in temperature and current, it is preferable that the wavelengths of light generated by each active layer are different in two-dimensional directions in a plan view. In other words, the wavelengths of light generated by at least two active layers arranged in the optical axis direction may be different from each other, or the wavelengths of light generated by at least two active layers arranged in the in-plane direction may be different from each other.

The above description of the light-emitting element array according to the sixth embodiment of the present technology can be applied to other embodiments of the present technology, unless there is a particular technical contradiction.

[7. Seventh embodiment of the present technology (example 1 of electronic device)]
An electronic device according to an embodiment of the present technology is an electronic device including the light-emitting element 100 according to any one of the first to eighth embodiments of the present technology. Since the electronic device includes the light-emitting element 100, it is possible to reduce the influence of temperature changes.

One example of electronic equipment is a distance measuring device. Fig. 9 is a block diagram showing a schematic configuration example of a distance measuring device (distance measuring device) 1000 including a surface emitting laser (light emitting element) 100 according to an embodiment of the present technology. The distance measuring device 1000 measures the distance to a subject S using a TOF (Time Of Flight) method. The distance measuring device 1000 includes the light emitting element 100 as a light source. The distance measuring device 1000 includes, for example, the light emitting element 100, a light receiving device 125, lenses 117, 130, a signal processing unit 140, a control unit 150, a display unit 160, and a memory unit 170.

The light-emitting element 100 is driven by a laser driver (driver). The laser driver has an anode terminal and a cathode terminal that are connected to the anode electrode and cathode electrode of the light-emitting element 100 via wiring or conductive bumps, respectively. The laser driver is configured to include circuit elements such as capacitors and transistors.

The light receiving device 125 detects the light reflected by the subject S. The lens 117 is a collimating lens that converts the light emitted from the light emitting element 100 into parallel light. The lens 130 is a focusing lens that collects the light reflected by the subject S and guides it to the light receiving device 125.

The signal processing unit 140 is a circuit for generating a signal corresponding to the difference between the signal input from the light receiving device 125 and the reference signal input from the control unit 150. The control unit 150 is configured to include, for example, a Time to Digital Converter (TDC). The reference signal may be a signal input from the control unit 150, or may be an output signal of a detection unit that directly detects the output of the light emitting element 100. The control unit 150 is, for example, a processor that controls the light emitting element 100, the light receiving device 125, the signal processing unit 140, the display unit 160, and the storage unit 170. The control unit 150 is a circuit that measures the distance to the specimen S based on the signal generated by the signal processing unit 140. The control unit 150 generates a video signal for displaying information about the distance to the specimen S and outputs it to the display unit 160. The display unit 160 displays information about the distance to the specimen S based on the video signal input from the control unit 150. The control unit 150 stores the information about the distance to the specimen S in the storage unit 170.

The above description of the electronic device according to the seventh embodiment of the present technology can be applied to other embodiments of the present technology, unless there is a particular technical contradiction.

[8. Eighth embodiment of the present technology (example 2 of electronic device)]
FIG. 10 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 present technology can be applied.

The vehicle control system 12000 includes a plurality of electronic control units connected via a communication network 12001. In the example shown in FIG. 10, 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.

The drive system control unit 12010 controls the operation of devices related to the drive system of the vehicle according to various programs. For example, the drive system control unit 12010 functions as a control device for a drive force generating device for generating the 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 for the vehicle.

The body system control unit 12020 controls the operation of various devices installed 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, tail lamps, brake lamps, turn signals, and fog lamps. In this case, radio waves or signals from various switches transmitted from a portable device that replaces a key can be input to the body system control unit 12020. The body system control unit 12020 accepts the input of these radio waves or signals and controls the vehicle's door lock device, power window device, lamps, etc.

The outside-vehicle information detection unit 12030 detects information outside the vehicle equipped with the vehicle control system 12000. For example, a distance measurement device 12031 is connected to the outside-vehicle information detection unit 12030. The distance measurement device 12031 includes the distance measurement device 1000 described above. The outside-vehicle information detection unit 12030 causes the distance measurement device 12031 to measure the distance to an object outside the vehicle (subject S), and acquires the distance data obtained thereby. The outside-vehicle information detection unit 12030 may perform object detection processing of people, cars, obstacles, signs, etc. based on the acquired distance data.

The in-vehicle information detection unit 12040 detects information inside the vehicle. To the in-vehicle information detection unit 12040, for example, a driver state detection unit 12041 that detects the state of the driver is connected. 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 driver's degree of fatigue or concentration based on the detection information input from the driver state detection unit 12041, or may determine whether the driver is dozing off.

The microcomputer 12051 can calculate control target values for the driving force generating device, steering mechanism, or braking device based on 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, or vehicle lane departure warning.

The microcomputer 12051 can also control the driving force generating device, steering mechanism, braking device, etc. based on information about the surroundings of the vehicle acquired by the outside vehicle information detection unit 12030 or the inside vehicle information detection unit 12040, thereby performing cooperative control aimed at automatic driving, which allows the vehicle to travel autonomously without relying on the driver's operation.

The microcomputer 12051 can also output control commands to the body system control unit 12020 based on information outside the vehicle acquired by the outside-vehicle 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-vehicle information detection unit 12030, and perform cooperative control aimed at preventing glare, such as switching high beams to low beams.

The audio/image output unit 12052 transmits at least one output signal of audio and image to an output device capable of visually or audibly notifying the occupants of the vehicle or the outside of the vehicle of information. In this example, an audio speaker 12061, a display unit 12062, and an instrument panel 12063 are exemplified as output devices. The display unit 12062 may include, for example, at least one of an on-board display and a head-up display.

FIG. 11 is a diagram showing an example of the installation position of a distance measurement device 12031 according to an embodiment of the present technology. In FIG. 11, a vehicle 12100 has distance measurement devices 12101, 12102, 12103, 12104, and 12105 as the distance measurement device 12031.

The distance measuring devices 12101, 12102, 12103, 12104, and 12105 are provided, for example, on the front nose, side mirrors, rear bumper, back door, and the top of the windshield inside the vehicle cabin of the vehicle 12100. The distance measuring device 12101 provided on the front nose and the distance measuring device 12105 provided on the top of the windshield inside the vehicle cabin mainly obtain data in front of the vehicle 12100. The distance measuring devices 12102 and 12103 provided on the side mirrors mainly obtain data on the sides of the vehicle 12100. The distance measuring device 12104 provided on the rear bumper or back door mainly obtains data on the rear of the vehicle 12100. The forward data obtained by the distance measuring devices 12101 and 12105 is mainly used to detect preceding vehicles, pedestrians, obstacles, traffic lights, traffic signs, etc.

Note that FIG. 11 shows an example of the detection ranges of distance measuring devices 12101 to 12104. Detection range 12111 indicates the detection range of distance measuring device 12101 provided on the front nose, detection ranges 12112 and 12113 indicate the detection ranges of distance measuring devices 12102 and 12103 provided on the side mirrors, respectively, and detection range 12114 indicates the detection range of distance measuring device 12104 provided on the rear bumper or back door.

For example, the microcomputer 12051 can determine the distance to each three-dimensional object within the detection ranges 12111 to 12114 and the change in this distance over time (relative speed with respect to the vehicle 12100) based on the distance data obtained from the distance measuring devices 12101 to 12104, and can extract as a preceding vehicle, in particular, the closest three-dimensional object on the path of the vehicle 12100 that is traveling in approximately the same direction as the vehicle 12100 at a predetermined speed (e.g., 0 km/h or faster). Furthermore, the microcomputer 12051 can set the inter-vehicle distance that should be maintained in advance in front of the preceding vehicle, and perform automatic braking control (including follow-up stop control) and automatic acceleration control (including follow-up start control). In this way, cooperative control can be performed for the purpose of automatic driving, which runs autonomously without relying on the driver's operation.

For example, the microcomputer 12051 classifies and extracts three-dimensional object data on three-dimensional objects, such as two-wheeled vehicles, ordinary vehicles, large vehicles, pedestrians, utility poles, and other three-dimensional objects, based on the distance data obtained from the distance measuring devices 12101 to 12104, and can use the data to automatically avoid obstacles. 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 the collision risk, which indicates the degree of risk of collision with each obstacle, and when the collision risk is equal to or exceeds a set value and there is a possibility of a collision, it 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 forcibly decelerating or steering to avoid a collision via the drive system control unit 12010.

The above description of the electronic device according to the eighth embodiment of the present technology can be applied to other embodiments of the present technology, unless there is a particular technical contradiction.

Note that the embodiments of this technology are not limited to the above-mentioned embodiments, and various modifications are possible without departing from the spirit of this technology. The specific values, shapes, materials (including compositions), etc. described in each embodiment are merely examples, and are not intended to be limiting.

The present technology can also be configured as follows.
[1]
at least two active layers including quantum nanostructures;
A light-emitting device, wherein at least two of the active layers generate light having wavelengths different from each other.
[2]
The quantum nanostructure includes any one selected from the group consisting of a quantum well structure, a quantum wire, and a quantum dot.
The light-emitting element according to [1].
[3]
The shapes of the quantum nanostructures included in at least two of the active layers are different from each other.
The light-emitting element according to [1] or [2].
[4]
The lengths of the quantum wells included in at least two of the active layers in the optical axis direction are different from each other.
The light-emitting element according to [2].
[5]
The compositions of the quantum nanostructures contained in at least two of the active layers are different from each other;
The light-emitting element according to any one of [1] to [4].
[6]
The shapes of the quantum dots included in at least two of the active layers are different from each other in a direction perpendicular to the optical axis direction.
The light-emitting element according to any one of [2] to [5].
[7]
The active layer has a structure in which the quantum nanostructure and a barrier layer are stacked on each other,
The shapes of the barrier layers included in at least two of the active layers are different from each other.
The light-emitting element according to any one of [1] to [6].
[8]
The active layer has a structure in which the quantum nanostructure and a barrier layer are stacked on each other,
The barrier layers included in at least two of the active layers have different compositions.
The light-emitting element according to any one of [1] to [7].
[9]
The active layer has a structure in which the quantum nanostructure and a barrier layer are stacked on each other,
The barrier layers of at least two of the active layers are doped with impurities having different concentrations from each other.
The light-emitting element according to any one of [1] to [8].
[10]
The active layer has a structure in which the quantum nanostructure and a barrier layer are stacked on each other,
The barrier layers of at least two of the active layers have different doping profiles of impurities.
The light-emitting element according to any one of [1] to [9].
[11]
a first compound semiconductor layer having a first conductivity type, a second compound semiconductor layer having a second conductivity type, and the active layer are laminated in this order;
the first compound semiconductor layer and the second compound semiconductor layer are tunnel-junctioned with each other;
The light-emitting element according to any one of [1] to [10].
[12]
a first compound semiconductor layer having a first conductivity type, a second compound semiconductor layer having a second conductivity type, and the active layer are laminated in this order;
the first compound semiconductor layer and the second compound semiconductor layer are wafer-bonded to each other;
The light-emitting element according to any one of [1] to [11].
[13]
a first compound semiconductor layer having a first conductivity type, a second compound semiconductor layer having a second conductivity type, and the active layer are laminated in this order;
the first compound semiconductor layer and the second compound semiconductor layer are tunnel-junctioned and wafer-bonded to each other;
The light-emitting element according to any one of [1] to [12].
[14]
The active layer is configured such that the photoluminescence wavelength becomes longer as the light intensity increases.
The light-emitting element according to any one of [1] to [13].
[15]
It is an edge-emitting laser.
The light-emitting element according to any one of [1] to [14].
[16]
A surface emitting laser.
The light-emitting element according to any one of [1] to [15].
[17]
A plurality of light-emitting elements according to any one of [1] to [16] are arranged two-dimensionally in a plan view,
A light-emitting element array, wherein the shapes of the quantum nanostructures included in the active layers of at least two of the light-emitting elements are different from each other.
[18]
A plurality of light-emitting elements according to any one of [1] to [16] are arranged two-dimensionally in a plan view,
A light-emitting element array, wherein the quantum nanostructures contained in the active layers of at least two of the light-emitting elements have compositions different from each other.
[19]
An electronic device comprising the light-emitting element according to any one of [1] to [16].

Reference Signs List 100 Light emitting element 10 First compound semiconductor layer 11 First cladding layer 20 Second compound semiconductor layer 21 Second cladding layer 30 Active layer 31 Quantum well layer 32 Barrier layer 40 Bonding layer 200 Light emitting element array

Claims

at least two active layers including quantum nanostructures;
A light-emitting device, wherein at least two of the active layers generate light having wavelengths different from each other.
The quantum nanostructure includes any one selected from the group consisting of a quantum well structure, a quantum wire, and a quantum dot.
The light-emitting device according to claim 1 .
The shapes of the quantum nanostructures included in at least two of the active layers are different from each other.
The light-emitting device according to claim 1 .
The lengths of the quantum wells included in at least two of the active layers in the optical axis direction are different from each other.
The light-emitting device according to claim 2 .
The compositions of the quantum nanostructures contained in at least two of the active layers are different from each other;
The light-emitting device according to claim 1 .
The shapes of the quantum dots included in at least two of the active layers are different from each other in a direction perpendicular to the optical axis direction.
The light-emitting device according to claim 2 .
The active layer has a structure in which the quantum nanostructure and a barrier layer are stacked on each other,
The shapes of the barrier layers included in at least two of the active layers are different from each other.
The light-emitting device according to claim 1 .
The active layer has a structure in which the quantum nanostructure and a barrier layer are stacked on each other,
The barrier layers included in at least two of the active layers have different compositions.
The light-emitting device according to claim 1 .
The active layer has a structure in which the quantum nanostructure and a barrier layer are stacked on each other,
The barrier layers of at least two of the active layers are doped with impurities having different concentrations from each other.
The light-emitting device according to claim 1 .
The active layer has a structure in which the quantum nanostructure and a barrier layer are stacked on each other,
The barrier layers of at least two of the active layers have different doping profiles of impurities.
The light-emitting device according to claim 1 .
a first compound semiconductor layer having a first conductivity type, a second compound semiconductor layer having a second conductivity type, and the active layer are laminated in this order;
the first compound semiconductor layer and the second compound semiconductor layer are tunnel-junctioned with each other;
The light-emitting device according to claim 1 .
a first compound semiconductor layer having a first conductivity type, a second compound semiconductor layer having a second conductivity type, and the active layer are laminated in this order;
the first compound semiconductor layer and the second compound semiconductor layer are wafer-bonded to each other;
The light-emitting device according to claim 1 .
a first compound semiconductor layer having a first conductivity type, a second compound semiconductor layer having a second conductivity type, and the active layer are laminated in this order;
the first compound semiconductor layer and the second compound semiconductor layer are tunnel-junctioned and wafer-bonded to each other;
The light-emitting device according to claim 1 .
The active layer is configured such that the photoluminescence wavelength becomes longer as the light intensity increases.
The light-emitting device according to claim 1 .
It is an edge-emitting laser.
The light-emitting device according to claim 1 .
A surface emitting laser.
The light-emitting device according to claim 1 .
A plurality of light-emitting elements according to claim 1 are arranged two-dimensionally in a plan view,
A light-emitting element array, wherein the shapes of the quantum nanostructures included in the active layers of at least two of the light-emitting elements are different from each other.
A plurality of light-emitting elements according to claim 1 are arranged two-dimensionally in a plan view,
A light-emitting element array, wherein the quantum nanostructures contained in the active layers of at least two of the light-emitting elements have compositions different from each other.
An electronic device equipped with the light-emitting device according to claim 1.