WO2023238655A1

WO2023238655A1 - Semiconductor light emitting element

Info

Publication number: WO2023238655A1
Application number: PCT/JP2023/019160
Authority: WO
Inventors: 茂生林; 真治吉田; 靖利川口; 貴大岡口
Original assignee: ヌヴォトンテクノロジージャパン株式会社
Priority date: 2022-06-07
Filing date: 2023-05-23
Publication date: 2023-12-14

Abstract

A semiconductor light emitting element (1) according to the present invention comprises: a substrate (10); a first cladding layer (30) of a first conductivity type, the first cladding layer (30) being arranged above the substrate (10); an active layer (40) which is arranged above the first cladding layer (30); a second cladding layer (50) of a second conductivity type, which is different from the first conductivity type, the second cladding layer (50) being arranged above the active layer (40); and a light guide layer (60) which is arranged between the first cladding layer (30) and the second cladding layer (50). The peak photon energy of the photoluminescence of the active layer (40) is higher than the peak photon energy of the laser light emitted from the semiconductor light emitting element (1), into which an electric current has been injected, by 0.050 eV or more.

Description

semiconductor light emitting device

The present disclosure relates to a semiconductor light emitting device.

Semiconductor light-emitting devices such as semiconductor laser devices that emit light from an active layer are conventionally known (see Patent Document 1, etc.). The semiconductor light emitting device described in Patent Document 1 includes an active layer having a quantum well structure including a well layer made of InGaN. The semiconductor laser device described in Patent Document 1 oscillates in the vicinity of the peak wavelength of the photoluminescence (PL) spectrum of the active layer (that is, in the wavelength range where high optical gain can be obtained).

JP2009-252861A

However, when the laser oscillation wavelength is near the peak wavelength of the PL spectrum, the laser light generated by the semiconductor light emitting element is absorbed by the active layer. Therefore, the light output efficiency of the semiconductor light emitting device decreases. Furthermore, as the temperature of the active layer increases due to the energy of the absorbed laser light, thermal saturation in which the optical output is saturated and COD (catastrophic optical damage) may occur.

A known countermeasure against COD caused by absorption of laser light near the cavity end face of a semiconductor light emitting device is to reduce the absorption of laser light by increasing the bandgap energy of the active layer near the cavity end face. There is. This makes it possible to suppress COD near the cavity end face, but it is not possible to reduce absorption of laser light in areas other than the vicinity of the cavity end face. Therefore, the effect of suppressing thermal saturation by this measure is low.

The present disclosure aims to solve such problems, and to provide a semiconductor light emitting device that can reduce light absorption in the active layer.

In order to solve the above problems, one embodiment of a semiconductor light emitting device according to the present disclosure includes a substrate, a first cladding layer of a first conductivity type disposed above the substrate, and a first cladding layer disposed above the first cladding layer. a second cladding layer disposed above the active layer and having a second conductivity type different from the first conductivity type; and a second cladding layer disposed between the first cladding layer and the second cladding layer. and a light guide layer in which the peak photon energy of photoluminescence of the active layer is higher by 0.050 eV or more than the peak photon energy of laser light emitted from the semiconductor light emitting element into which current is injected.

In order to solve the above problems, another aspect of the semiconductor light emitting device according to the present disclosure includes a substrate, a first cladding layer of a first conductivity type disposed above the substrate, and a first cladding layer of the first conductivity type. an active layer disposed above; a second cladding layer of a second conductivity type different from the first conductivity type disposed above the active layer; and between the first cladding layer and the second cladding layer. in the photoluminescence spectrum of the active layer, the intensity of the photoluminescence at the peak photon energy of the laser light emitted from the semiconductor light emitting device into which current is injected is equal to the spectrum of the photoluminescence of the active layer; It is 40% or less of the peak intensity.

In order to solve the above problems, another aspect of the semiconductor light emitting device according to the present disclosure is a semiconductor light emitting device including an active layer, wherein the peak photon energy of photoluminescence of the active layer is It is 0.070 eV or more higher than the peak photon energy of spontaneous emission light emitted from the semiconductor light emitting device.

In order to solve the above problems, another aspect of the semiconductor light emitting device according to the present disclosure includes a substrate, a first cladding layer of a first conductivity type disposed above the substrate, and a first cladding layer of the first conductivity type. an active layer disposed above; a second cladding layer of a second conductivity type different from the first conductivity type disposed above the active layer; and between the first cladding layer and the second cladding layer. the active layer has a quantum well structure in which two or more barrier layers and one or more well layers are alternately laminated, and each of the two or more barrier layers and each of the one or more well layers is 0.140 eV or less, and the optical guide layer is a first cladding layer disposed between the first cladding layer and the active layer. Each of the first light guide layer and the second light guide layer has at least one of a light guide layer and a second light guide layer disposed between the active layer and the second cladding layer. has a band gap energy smaller than the two or more barrier layers and a band gap energy larger than the one or more well layers, and the first light guide layer and the first light guide layer among the two or more barrier layers. The difference in band gap energy between the barrier layer closest to the guide layer is less than 0.080 eV, and the second light guide layer and the barrier layer closest to the second light guide layer among the two or more barrier layers The difference in band gap energy between the two is less than 0.080 eV.

According to the present disclosure, it is possible to provide a semiconductor light emitting device that can reduce light absorption in the active layer.

FIG. 1 is a schematic top view showing the overall configuration of a semiconductor light emitting device according to an embodiment. 1 is a schematic cross-sectional view showing the overall configuration of a semiconductor light emitting device according to an embodiment. 3 is a graph showing an example of a PL spectrum of a semiconductor light emitting device according to an embodiment. It is a graph which shows an example of the PL spectrum of the element which removed the active layer from the semiconductor light emitting element based on embodiment. It is a graph showing an example of a PL spectrum of an active layer concerning an embodiment. FIG. 3 is a diagram showing the layer structure of each example of the semiconductor light emitting device according to the embodiment. 1 is a schematic cross-sectional view showing the structure of an active layer of a semiconductor light emitting device according to Example 1. FIG. 3 is a graph schematically showing a bandgap energy distribution in the stacking direction of the semiconductor light emitting device according to Example 1. FIG. 3 is a graph schematically showing the bandgap energy distribution in the stacking direction of the semiconductor light emitting device according to Example 2. FIG. 12 is a graph schematically showing a bandgap energy distribution in the stacking direction of a semiconductor light emitting device according to Example 4. It is a figure which shows the characteristic of each Example of embodiment. 12 is a graph showing the relationship between the injection current and the optical output of the semiconductor light emitting device according to Example 5. 7 is a graph showing the relationship between the light output of the semiconductor light emitting device according to Example 5 and the ratio of the light output to input power. It is a graph which shows the laser beam spectrum and PL spectrum of the semiconductor light emitting device of a comparative example. 3 is a graph showing a laser beam spectrum and a PL spectrum of a semiconductor light emitting device according to Example 1. FIG. 3 is a graph showing the relationship between the optical output at the output saturation starting point of the semiconductor light emitting device according to each example and the semiconductor light emitting device of the comparative example and the PL-laser light energy difference. 3 is a graph showing the relationship between the slope efficiency and the PL-laser light energy difference when the optical output of the semiconductor light emitting device according to each example and the semiconductor light emitting device of the comparative example is 0.5 W or more and 1.0 W or less. 2 is a graph showing a spontaneous emission spectrum and a PL spectrum of a semiconductor light emitting device according to a comparative example. 2 is a graph showing a spontaneous emission spectrum and a PL spectrum of a semiconductor light emitting device according to Example 1. 3 is a graph showing a spontaneous emission spectrum and a PL spectrum of a semiconductor light emitting device according to Example 2. 3 is a graph showing a spontaneous emission spectrum and a PL spectrum of a semiconductor light emitting device according to Example 5. 3 is a graph showing the relationship between the light output at the output saturation starting point of the semiconductor light emitting device according to each example and the semiconductor light emitting device of the comparative example and the PL-spontaneous emission light energy difference. 3 is a graph showing the relationship between the slope efficiency and the PL-laser light energy difference when the optical output of the semiconductor light emitting device according to each example and the semiconductor light emitting device of the comparative example is 0.5 W or more and 1.0 W or less.

Hereinafter, embodiments of the present disclosure will be described with reference to the drawings. Note that the embodiments described below each represent a specific example of the present disclosure. Therefore, the numerical values, shapes, materials, components, arrangement positions and connection forms of the components shown in the following embodiments are merely examples and do not limit the present disclosure.

Furthermore, each figure is a schematic diagram and is not necessarily strictly illustrated. Therefore, the scale etc. in each figure are not necessarily the same. In addition, in each figure, the same code|symbol is attached to the substantially the same structure, and the overlapping description is omitted or simplified.

Furthermore, in this specification, the terms "upper" and "lower" do not refer to the upper direction (vertically upward) or the lower direction (vertically downward) in absolute spatial recognition, but are based on the stacking order in the stacked structure. Used as a term defined by the relative positional relationship. Additionally, the terms "above" and "below" are used not only when two components are spaced apart and there is another component between them; This also applies when they are placed in contact with each other.

(Embodiment)
A semiconductor light emitting device according to an embodiment will be described.

[1. Basic configuration]
The basic configuration of the semiconductor light emitting device according to this embodiment will be explained using FIG. 1. 1 and 2 are a schematic top view and a cross-sectional view, respectively, showing the basic configuration of a semiconductor light emitting device 1 according to this embodiment. Note that each figure shows an X-axis, a Y-axis, and a Z-axis that are orthogonal to each other. The X, Y, and Z axes are a right-handed Cartesian coordinate system. The stacking direction of the semiconductor light emitting device 1 (that is, the thickness direction of each layer included in the semiconductor light emitting device 1) is parallel to the Z-axis direction, and the main propagation direction of light (laser light) is parallel to the Y-axis direction. be.

The semiconductor light emitting device 1 is a device that emits light by current injection. In this embodiment, the semiconductor light emitting device 1 is a semiconductor laser device that emits laser light with a peak wavelength of 400 nm or less (peak photon energy of 3.1 eV or less). As shown in FIG. 1, the semiconductor light emitting device 1 has two end faces 1F and 1R forming a resonator. The end surface 1F is a front end surface that emits laser light, and the end surface 1R is a rear end surface that has a higher reflectance than the end surface 1F. Further, the semiconductor light emitting device 1 has a waveguide formed between the end surface 1F and the end surface 1R.

The resonator length of the semiconductor light emitting device 1, that is, the distance between the end surfaces 1F and 1R in the laser beam propagation direction (the Y-axis direction in each figure, that is, the resonance direction) is not particularly limited, but in this embodiment , 1200 μm. The semiconductor light emitting device 1 may include a reflective film disposed at the end in the propagation direction of the laser beam. The reflective films are films for adjusting the reflectance of the end faces 1F and 1R, respectively. A dielectric multilayer film or the like can be used as the reflective film.

As shown in FIG. 2, the semiconductor light emitting device 1 includes a substrate 10, a first cladding layer 30 disposed above the substrate 10, an active layer 40 disposed above the first cladding layer 30, and an active layer 40 disposed above the first cladding layer 30. A second cladding layer 50 disposed above the layer 40 and a light guide layer 60 disposed between the first cladding layer 30 and the second cladding layer 50 are provided. In this embodiment, the semiconductor light emitting device 1 includes a base layer 21 disposed between the substrate 10 and the first cladding layer 30, and a crack prevention layer disposed between the base layer 21 and the first cladding layer 30. an electron blocking layer 70 disposed between the active layer 40 and the second cladding layer 50; an insulating layer 80 disposed above the second cladding layer 50; The semiconductor device further includes an upper electrode 91 and a lower electrode 92 arranged on the lower surface of the substrate 10 (that is, the main surface on the back side of the main surface on which each semiconductor layer is laminated).

The substrate 10 is a plate-like member that serves as a base for the semiconductor light emitting device 1. In this embodiment, the first conductivity type is N type.

The base layer 21 is a first conductivity type semiconductor layer disposed above the substrate 10. In this embodiment, base layer 21 is laminated on the main surface of substrate 10 .

The crack prevention layer 22 is a first conductivity type semiconductor layer disposed above the substrate 10. In this embodiment, crack prevention layer 22 is placed above base layer 21 .

The first cladding layer 30 is a first conductivity type semiconductor layer disposed above the substrate 10. The average refractive index of the first cladding layer 30 is lower than the average refractive index of the active layer 40. Here, the average refractive index of the first cladding layer 30 etc. is defined as the value obtained by integrating the refractive index in the thickness direction of the layer divided by the thickness of the layer. In this embodiment, first cladding layer 30 is placed above crack prevention layer 22 .

The active layer 40 is a light emitting layer disposed above the first cladding layer 30. In this embodiment, the peak photon energy of the PL of the active layer 40 is higher than the peak photon energy of the laser light emitted from the semiconductor light emitting device 1 into which current is injected by 0.050 eV or more.

Here, the direction in which the peak photon energy of PL of the active layer 40 is measured will be explained using FIGS. 3 to 5. FIG. 3 is a graph showing an example of the PL spectrum of the semiconductor light emitting device 1 according to this embodiment. FIG. 4 is a graph showing an example of the PL spectrum of the semiconductor light emitting device 1 according to the present embodiment from which the active layer 40 is removed. FIG. 5 is a graph showing an example of the PL spectrum of the active layer 40 according to this embodiment. The horizontal axis of each graph in FIGS. 3 to 5 indicates the photon energy corresponding to the PL wavelength, and the vertical axis indicates the normalized PL intensity.

In order to measure the PL spectrum of the active layer 40, first, the semiconductor light emitting device 1 is optically excited using a He--Cd laser with a wavelength of 325 nm, and the spectrum of PL emitted from the semiconductor light emitting device 1 is measured. For example, in a GaN-based semiconductor laser device, when the peak wavelength is 400 nm or less, GaN is often used as the substrate and InGaN is used as the crack prevention layer 22. In this case, the bandgap energy of the crack prevention layer 22 is lower than that of the base layer 21 and the first cladding layer 30, so the PL spectrum obtained by the above-mentioned measurement includes an active region as shown in FIG. Not only the PL of layer 40 but also the PL of anti-crack layer 22 is included. Therefore, by removing the upper part of the optical guide layer 60 including the active layer 40 from the semiconductor light emitting device 1, the spectrum of PL emitted from the part is optically excited using a He-Cd laser with a wavelength of 325 nm (see Fig. 4) Measure. By removing the PL component of the crack prevention layer 22 shown in FIG. 4 from the PL spectrum of the semiconductor light emitting device 1 as shown in FIG. 3, the PL spectrum of the active layer 40 as shown in FIG. 5 is obtained. be able to. At this time, the intensity of the spectrum shown in FIG. 4 is adjusted so that the peak of the PL spectrum of the crack prevention layer 22 does not remain in the spectrum after removal shown in FIG. Specifically, while the peak intensity at a position near 3.31 eV in FIG. 3 is 0.91, the intensity is adjusted so that the peak intensity in FIG. 4 is 0.84. As a result, in the spectrum of FIG. 5 obtained by subtracting the spectrum intensity of FIG. 4 from the spectrum intensity of FIG. 3, no peak is seen around 3.31 eV.

When removing the active layer 40 from the semiconductor light emitting device 1, wet etching can be used, for example. Specifically, first, the upper electrode 91 and the lower electrode 92 are removed using an aqua regia-based etchant. Subsequently, the insulating layer 80 is removed using a hydrofluoric acid-based etchant. Subsequently, the active layer 40 and the semiconductor layer disposed above it are removed by reactive ion etching. For example, the first light guide layer 61 and the semiconductor layer disposed above it may be removed by reactive ion etching.

In this embodiment, the active layer 40 has a quantum well structure in which two or more barrier layers and one or more well layers are alternately stacked. The difference in band gap energy between each of the two or more barrier layers and each of the one or more well layers is 0.140 eV or less.

The second cladding layer 50 is a semiconductor layer of a second conductivity type different from the first conductivity type, which is disposed above the active layer 40. The average refractive index of the second cladding layer 50 is lower than the average refractive index of the active layer 40. In this embodiment, the second cladding layer 50 is arranged above the light guide layer 60 and the electron block layer 70. The second conductivity type is P type.

In this embodiment, a ridge 50R extending in the light propagation direction (that is, the Y-axis direction) is formed in the second cladding layer 50. In other words, two grooves 50T extending along the light propagation direction are formed on the upper surface of the second cladding layer 50, and a ridge 50R is formed between the two grooves 50T. A waveguide is formed along the ridge 50R. In addition, in FIG. 1, the upper surface of the ridge 50R and the outline of the groove 50T are shown by broken lines. The width of the ridge 50R (that is, the dimension of the upper surface of the ridge 50R in the X-axis direction) is, for example, 15 μm.

The light guide layer 60 is a semiconductor layer disposed between the first cladding layer 30 and the second cladding layer 50. The light guide layer 60 includes a first light guide layer 61 disposed between the first cladding layer 30 and the active layer 40 and a second light guide layer 61 disposed between the active layer 40 and the second cladding layer 50. It has at least one of the guide layers 62. Note that FIG. 2 shows an example in which the light guide layer 60 includes both a first light guide layer 61 and a second light guide layer 62. Each of the first light guide layer 61 and the second light guide layer 62 has a smaller band gap energy than the barrier layers 41 and 43 and a larger band gap energy than the well layer 42 .

The electron block layer 70 is a semiconductor layer disposed between the active layer 40 and the second cladding layer 50. The electron block layer 70 is a semiconductor layer having a larger bandgap energy than the second cladding layer 50. Thereby, the electron blocking layer 70 functions as a barrier for electrons traveling from the active layer 40 to the second cladding layer 50, thereby confining the electrons in the active layer 40. In the example shown in FIG. 2, the electron blocking layer 70 is disposed between the second light guide layer 62 and the second cladding layer 50.

The insulating layer 80 is an electrically insulating layer disposed above the second cladding layer 50. In this embodiment, the insulating layer 80 is arranged in a region of the upper surface of the second cladding layer 50 other than the upper surface of the ridge 50R.

The upper electrode 91 is a conductive layer placed above the second cladding layer 50. In this embodiment, upper electrode 91 is used as an electrode for injecting current into semiconductor light emitting device 1 through the opening in insulating layer 80 . The upper electrode 91 is arranged on at least a portion of the upper surface of the ridge 50R of the second cladding layer 50.

The lower electrode 92 is an electrode placed on the lower surface of the substrate 10 and is used as an electrode for injecting current into the semiconductor light emitting device 1.

[2. Example]
An example of the semiconductor light emitting device 1 according to this embodiment will be described using FIG. 6. FIG. 6 is a diagram showing the layer structure of each example of the semiconductor light emitting device 1 according to the present embodiment. FIG. 6 shows the composition and film thickness of each layer included in the semiconductor light emitting device 1 according to each example and the semiconductor light emitting device of the comparative example. FIG. 6 also shows the difference in band gap energy between the barrier layer and the well layer, and the band gap energy ( The difference in bandgap energy (Eg) between the top barrier layer (the barrier layer closest to the second light guide layer 62) and the second light guide layer 62 are also shown. Hereinafter, detailed configurations of a semiconductor light emitting device of a comparative example and a semiconductor light emitting device 1 according to each example will be described.

[2-1. Comparative example]
The semiconductor light emitting device of the comparative example shown in FIG. 6, like the semiconductor light emitting device 1 according to the present embodiment, includes a substrate, a base layer, a crack prevention layer, a first cladding layer, and a first optical guide layer. , an active layer, an electron blocking layer, a second optical guide layer, and a second cladding layer. Although not shown in FIG. 6, the semiconductor light emitting device of the comparative example also includes an insulating layer, an upper electrode, and a lower electrode, similarly to the semiconductor light emitting device 1 according to the present embodiment.

The substrate of the semiconductor light emitting device of the comparative example is an N-type GaN substrate doped with Si as an impurity. The base layer is an N-type Al _0.02 Ga _0.98 N layer with a thickness of 1000 nm. The crack prevention layer is an N-type In _0.03 Ga _0.97 N layer with a thickness of 150 nm. The first cladding layer is an N-type Al _0.065 Ga _0.935 N layer doped with Si at a concentration of 5×10 ¹⁷ cm ⁻³ and has a thickness of 540 nm. The first optical guide layer consists of an N-type Al _0.03 Ga _0.97 N layer doped with Si at a concentration of 5×10 ¹⁷ cm ⁻³ with a thickness of 127 nm, and a layer with a thickness of 180 nm disposed on the layer. undoped Al _0.02 Ga _0.98 N layer.

The active layer includes a well layer which is an undoped In _0.01 Ga _0.99 N layer with a thickness of 7.5 nm, and an undoped Al _0.05 Ga _0.95 N layer with a thickness of 12 nm placed below the well layer. and a barrier layer that is an undoped Al _0.05 Ga _0.95 N layer with a thickness of 12 nm disposed above the well layer. As shown in FIG. 6, in the active layer of the comparative example, unlike the active layer 40 according to the present embodiment, the difference in band gap energy between each barrier layer and the well layer is larger than 0.140 eV. The difference in band gap energy between each barrier layer and well layer of the active layer of the comparative example is 0.163 eV.

The second optical guide layer is a P-type Al _0.02 Ga _0.98 N layer with a thickness of 66 nm. The electron block layer is a P-type Al _0.36 Ga _0.64 N layer with a thickness of 5.5 nm. The second cladding layer is a P-type Al _0.065 Ga _0.935 N layer doped with Mg at a concentration of 8×10 ¹⁸ cm ⁻³ and has a thickness of 660 nm.

In the semiconductor light emitting device of the comparative example, the difference in band gap energy between the first light guide layer and the barrier layer closest to the first light guide layer among the barrier layers of the active layer is 0.080 eV, The difference in band gap energy between the light guide layer and the barrier layer closest to the second light guide layer among the barrier layers of the active layer is 0.053 eV.

[2-2. Example 1]
The semiconductor light emitting device 1 according to Example 1 includes a substrate 10, a base layer 21, a crack prevention layer 22, a first cladding layer 30, a first light guide layer 61, an active layer 40, and a second light guide. layer 62 , an electron block layer 70 , and a second cladding layer 50 . The second light guide layer 62 according to Example 1 is disposed between the active layer 40 and the electron blocking layer 70.

The substrate 10, base layer 21, crack prevention layer 22, first light guide layer 61, and second cladding layer 50 of the semiconductor light emitting device 1 according to Example 1 have the same configuration as the semiconductor light emitting device of the comparative example.

The first cladding layer 30 according to Example 1 is an N-type Al _0.065 Ga _0.935 N layer doped with Si at a concentration of 5×10 ¹⁷ cm ⁻³ and has a thickness of 800 nm.

The active layer 40 according to Example 1 will be explained using FIG. 7. FIG. 7 is a schematic cross-sectional view showing the structure of the active layer 40 of the semiconductor light emitting device 1 according to Example 1. FIG. 7 shows a cross section of the semiconductor light emitting device 1 at the same position as in FIG. As shown in FIG. 7, the active layer 40 according to Example 1 includes a barrier layer 41, a well layer 42 disposed above the barrier layer 41, and a barrier layer 43 disposed above the well layer 42. has. The barrier layer 41 is an undoped Al _0.04 Ga _0.96 N layer with a thickness of 12 nm. The well layer 42 is an undoped In _0.01 Ga _0.99 N layer with a thickness of 17.5 nm. The barrier layer 43 is an undoped Al _0.03 Ga _0.97 N layer. Note that, as shown in FIG. 6, the barrier layer 43 and the second light guide layer 62 have the same composition (Al _0.03 Ga _0.97 N), and the barrier layer 43 and the second light guide layer 62 have the same composition (Al 0.03 Ga 0.97 N). The total film thickness with 62 is 130 nm. That is, of the undoped Al _0.03 Ga _0.97 N layer with a thickness of 130 nm disposed above the well layer 42 , a portion close to the well layer 42 functions as a barrier layer 43 , and a portion far from the well layer 42 functions as a barrier layer 43 . functions as the second light guide layer 62.

The electron block layer 70 is a P-type Al _0.36 Ga _0.64 N layer with a thickness of 1.6 nm.

The bandgap energy distribution of the semiconductor light emitting device 1 according to Example 1 will be explained using FIG. 8. FIG. 8 is a graph schematically showing the bandgap energy distribution in the stacking direction of the semiconductor light emitting device 1 according to Example 1.

As shown in FIG. 8 (and FIG. 6), in the semiconductor light emitting device 1 according to Example 1, the difference in band gap energy between each barrier layer of the active layer 40 and the well layer 42 is 0.140 eV or less. be.

Further, as shown in FIG. 6, in the semiconductor light emitting device 1 according to Example 1, the difference in band gap energy between the first optical guide layer 61 and the barrier layer 41 is 0.053 eV. Further, since the second optical guide layer 62 and the barrier layer 43 have the same composition, there is no difference in band gap energy.

[2-3. Example 2]
As shown in FIG. 6, the semiconductor light emitting device 1 according to Example 2 is mainly designed with respect to the positional relationship between the electron block layer 70 and the second light guide layer 62 and the composition of the first light guide layer 61. This is different from the semiconductor light emitting device 1 according to Example 1.

The substrate 10, base layer 21, and crack prevention layer 22 of the semiconductor light emitting device 1 according to Example 2 are the same as the substrate 10, base layer 21, and crack prevention layer 22 of the semiconductor light emitting device 1 according to Example 1 (and the semiconductor light emitting device of the comparative example), respectively. 21 and the crack prevention layer 22. The first cladding layer 30, the well layer 42, and the electron block layer 70 of the semiconductor light emitting device 1 according to Example 2 are the same as the first cladding layer 30, the well layer 42, and the electron block layer 70 of the semiconductor light emitting device 1 according to Example 1, respectively. It has the same configuration as the electronic block layer 70.

The first optical guide layer 61 according to Example 2 includes an N-type Al _0.03 Ga _0.97 N layer doped with Si at a concentration of 5×10 ¹⁷ cm ⁻³ and a thickness of 127 nm, and a layer on the layer. An undoped Al _0.03 Ga _0.97 N layer with a thickness of 90 nm is arranged. The barrier layer 41 is an undoped Al _0.04 Ga _0.96 N layer with a thickness of 10 nm. The barrier layer 43 is an undoped Al _0.03 Ga _0.97 N layer with a thickness of 20 nm. The second optical guide layer 62 is a 130 nm thick P-type Al _0.03 Ga _0.97 N layer disposed above the electron block layer 70 . The second light guide layer 62 is doped with Mg at a concentration of 3×10 ¹⁸ cm ⁻³ . The second cladding layer 50 is a P-type Al _0.065 Ga _0.935 N layer with a thickness of 450 nm.

The bandgap energy distribution of the semiconductor light emitting device 1 according to Example 2 will be explained using FIG. 9. FIG. 9 is a graph schematically showing the band gap energy distribution in the stacking direction of the semiconductor light emitting device 1 according to Example 2.

As shown in FIG. 9 (and FIG. 6), in the semiconductor light emitting device 1 according to Example 2, the difference in band gap energy between each barrier layer of the active layer 40 and the well layer 42 is 0.140 eV or less. be. Furthermore, in Example 2, the difference in band gap energy between the barrier layer 41 and the first optical guide layer 61 is smaller than in Example 1.

Further, as shown in FIG. 6, in the semiconductor light emitting device 1 according to Example 2, the difference in band gap energy between the first optical guide layer 61 and the barrier layer 41 is 0.027 eV. Further, since the second optical guide layer 62 and the barrier layer 43 have the same composition, there is no difference in band gap energy.

[2-4. Example 3]
As shown in FIG. 6, the semiconductor light emitting device 1 according to Example 3 differs from the semiconductor light emitting device 1 according to Example 2 mainly in that the second optical guide layer 62 has a low impurity (Mg) concentration. do.

The substrate 10, base layer 21, and crack prevention layer 22 of the semiconductor light emitting device 1 according to Example 3 are the same as the substrate 10, base layer 21, and crack prevention layer 22 of the semiconductor light emitting device 1 according to Example 2 (and the semiconductor light emitting device of the comparative example), respectively. 21 and the crack prevention layer 22. The first cladding layer 30, first optical guide layer 61, well layer 42, barrier layer 43, electron block layer 70, and second cladding layer 50 of the semiconductor light emitting device 1 according to Example 3 are the same as those of Example 2. It has the same configuration as the first cladding layer 30, first optical guide layer 61, well layer 42, barrier layer 43, electron block layer 70, and second cladding layer 50 of the semiconductor light emitting device 1.

The barrier layer 41 according to Example 3 is, like the barrier layer 41 according to Example 1, an undoped Al _0.04 Ga _0.96 N layer with a thickness of 12 nm. The second light guide layer 62 is a P-type Al _0.03 Ga _0.97 N layer with a film thickness of 130 nm like the second light guide layer 62 according to Example 2, but the impurity concentration is different from that of Example 2. It is lower than the second light guide layer 62. The Mg concentration of the second light guide layer 62 according to Example 3 is 2×10 ¹⁸ cm ⁻³ .

The band gap energy distribution of the semiconductor light emitting device 1 according to Example 3 is similar to the band gap energy distribution of the semiconductor light emitting device 1 according to Example 2. As shown in FIG. 6, in the semiconductor light emitting device 1 according to the third embodiment, as in the second embodiment, the difference in band gap energy between each barrier layer of the active layer 40 and the well layer 42 is 0. It is 140 eV or less.

[2-5. Example 4]
As shown in FIG. 6, the semiconductor light emitting device 1 according to Example 4 differs from the semiconductor light emitting device 1 according to Example 2 mainly in the composition of the barrier layer 43.

The substrate 10 and base layer 21 of the semiconductor light emitting device 1 according to Example 4 have the same configuration as the substrate 10 and base layer 21 of the semiconductor light emitting device 1 according to Example 2 (and the semiconductor light emitting device of the comparative example), respectively. has. The first cladding layer 30, the first optical guide layer 61, the well layer 42, the electron block layer 70, the second optical guide layer 62, and the second cladding layer 50 of the semiconductor light emitting device 1 according to Example 4 were It has the same configuration as the first cladding layer 30, first optical guide layer 61, well layer 42, electron block layer 70, second optical guide layer 62, and second cladding layer 50 of the semiconductor light emitting device 1 according to Example 2.

The crack prevention layer 22 according to Example 4 is an N-type In _0.04 Ga _0.96 N layer with a thickness of 150 nm. The first optical guide layer 61 consists of an N-type Al 0.03 Ga 0.97 N layer doped with Si at a concentration of 5×10 ¹⁷ cm ⁻³ and a thickness of 127 nm, and a layer of N-type Al _0.03 Ga _0.97 N layer disposed on the layer. It has an 80 nm undoped Al _0.03 Ga _0.97 N layer. The barrier layer 41 is an undoped Al _0.04 Ga _0.96 N layer with a thickness of 14 nm. The barrier layer 43 is an undoped Al _0.04 Ga _0.96 N layer with a thickness of 10 nm.

The bandgap energy distribution of the semiconductor light emitting device 1 according to Example 4 will be explained using FIG. 10. FIG. 10 is a graph schematically showing the band gap energy distribution in the stacking direction of the semiconductor light emitting device 1 according to Example 4.

As shown in FIG. 10 (and FIG. 6), in the semiconductor light emitting device 1 according to the fourth embodiment, as in the second embodiment, the band gap energy between each barrier layer of the active layer 40 and the well layer 42 is The difference is less than 0.140 eV. Furthermore, in the semiconductor light emitting device 1 according to the fourth embodiment, the bandgap energy of the barrier layer 43 is larger than the bandgap energy of the barrier layer 43 according to the second embodiment.

Further, as shown in FIG. 6, in the semiconductor light emitting device 1 according to Example 4, the difference in band gap energy between the first optical guide layer 61 and the barrier layer 41 is 0.027 eV. Further, the difference in band gap energy between the second optical guide layer 62 and the barrier layer 43 is also 0.027 eV.

[2-6. Example 5]
As shown in FIG. 6, the semiconductor light emitting device 1 according to Example 5 differs from the semiconductor light emitting device 1 according to Example 1 mainly in that the well layer 42 is an AlInGaN layer.

The substrate 10, base layer 21, crack prevention layer 22, and second cladding layer 50 of the semiconductor light emitting device 1 according to Example 5 are the semiconductor light emitting device 1 according to Example 1 (and the semiconductor light emitting device of the comparative example), respectively. It has the same structure as the substrate 10, base layer 21, crack prevention layer 22, and second cladding layer 50. The first cladding layer 30, the barrier layer 41, and the electron block layer 70 of the semiconductor light emitting device 1 according to Example 5 are the first cladding layer 30, the barrier layer 41, and the electron block layer 70 of the semiconductor light emitting device 1 according to Example 1, respectively. It has the same configuration as the electronic block layer 70.

The first optical guide layer 61 according to Example 5 is made of N-type Al 0 doped with Si at a concentration of 5×10 ¹⁷ cm ⁻³ and has a thickness of 127 nm, like the first optical guide layer 61 according to Example 2 _. It has _{a .03} Ga _0.97 N layer and a 90 nm thick P-type Al _0.03 Ga _0.97 N layer disposed on the layer. The well layer 42 is an undoped Al _0.02 In _0.035 Ga _0.945 N layer with a thickness of 17.5 nm. The barrier layer 43 is an undoped Al _0.03 Ga _0.97 N layer. As shown in FIG. 6, the barrier layer 43 and the second light guide layer 62 have the same composition (Al _0.03 Ga _0.97 N); The total film thickness is 70 nm. That is, of the undoped Al _0.03 Ga _0.97 N layer with a thickness of 70 nm disposed above the well layer 42 , a portion close to the well layer 42 functions as a barrier layer 43 , and a portion far from the well layer 42 functions as a barrier layer 43 . functions as the second light guide layer 62.

The band gap energy distribution of the semiconductor light emitting device 1 according to Example 5 is similar to the band gap energy distribution of the semiconductor light emitting device 1 according to Example 1. As shown in FIG. 6, in the semiconductor light emitting device 1 according to the fifth embodiment, as in the first embodiment, the difference in band gap energy between each barrier layer of the active layer 40 and the well layer 42 is 0. It is 140 eV or less.

[3. Characteristics and effects]
The characteristics and effects of the semiconductor light emitting device 1 according to this embodiment will be described using FIGS. 6 and 11 while comparing the above-mentioned comparative example and each example. FIG. 11 is a diagram showing the characteristics of each example of this embodiment. FIG. 11 shows the characteristics obtained through experiments of the semiconductor light emitting device 1 according to each example, as well as the characteristics obtained through experiments of the semiconductor light emitting device of the comparative example. Note that in FIG. 11, characteristics that have not been measured at the time of filing of the present disclosure are described as "unmeasured." Further, the characteristics of each semiconductor light emitting device shown in FIG. 11 during laser oscillation are those when the device is operated in continuous (CW) oscillation with an optical output of 0.3 W at room temperature.

The peak photon energy (peak position) and half-width (full width at half-maximum) of the spontaneous emission shown in FIG. This is the obtained value. The peak photon energy (peak position) and half-width (full width at half maximum) of the laser beam shown in FIG. 11 are obtained by measuring the emission spectrum of each semiconductor light-emitting element into which a current larger than the oscillation threshold is injected using a spectrum analyzer. is the value given.

The PL-laser light energy difference shown in FIG. 11 is the difference between the peak photon energy of the PL spectrum measured by the above-described method shown in FIG. 11 and the peak photon energy of the laser light.

The PL-Spontaneous emission light energy difference shown in FIG. 11 is the difference between the peak photon energy of the PL spectrum measured by the method described above and the peak photon energy of the spontaneous emission light shown in FIG.

The PL intensity ratio at the laser beam peak position shown in FIG. 11 is the ratio of the PL intensity at the peak photon energy of the laser beam emitted from the semiconductor light emitting element into which current is injected to the peak PL intensity.

The PL intensity ratio at a position 0.050 eV lower energy than the PL peak position shown in FIG. 11 is the ratio of the PL intensity at a photon energy 0.050 eV lower energy than the peak photon energy of the PL spectrum to the peak PL intensity. It is.

The slope efficiency and output saturation start point shown in FIG. 11 will be explained using, as an example, the characteristics of the semiconductor light emitting device 1 of Example 5 shown in FIGS. 12A and 12B. FIG. 12A is a graph showing the relationship between the injection current and the optical output of the semiconductor light emitting device 1 according to Example 5, in which the IL curve is shown as a solid line, and the slope efficiency curve (the slope of the IL curve ) is indicated by a dashed line. FIG. 12B is a graph showing the relationship between the optical output of the semiconductor light emitting device 1 according to Example 5 and the ratio of the optical output to input power (that is, wall plug efficiency WPE).

The slope efficiency is an increment in optical output per increment in current, and is a value corresponding to the slope of the IL curve shown in FIG. 12A. FIG. 11 shows the slope efficiency for each optical output range.

The output saturation starting point is a point corresponding to the inflection point where the slope of the IL curve begins to decrease, and as shown in FIG. 12A, the optical output at the output saturation starting point is 2.1 W (2100 mW). be. Further, the output saturation starting point may be defined as the point at which the ratio of the optical output to the input power to the semiconductor light emitting element becomes maximum, as shown in FIG. 12B.

First, the relationship between the peak photon energy of the laser beam of the semiconductor light emitting device 1 according to the present embodiment and the PL peak photon energy will be explained using FIGS. 13 and 14 while comparing with a comparative example. 13 and 14 are graphs showing the laser light spectrum and PL spectrum of the semiconductor light emitting device of the comparative example and the semiconductor light emitting device 1 according to Example 1, respectively. In FIGS. 13 and 14, the laser light spectrum is shown by a solid line, and the PL spectrum is shown by a broken line, respectively.

As shown in FIG. 13, in the semiconductor light emitting device of the comparative example, the peak photon energy of PL is 0.049 eV higher than the peak photon energy of laser light. On the other hand, in the semiconductor light emitting device 1 according to Example 1, the peak photon energy of PL is 0.112 eV higher than the peak photon energy of laser light. As described above, the semiconductor light emitting device 1 according to Example 1 has a larger PL-laser light energy difference than the semiconductor light emitting device of the comparative example. As a result, in the semiconductor light emitting device 1 according to Example 1, the intensity of PL at the peak photon energy of the laser beam is smaller than that of the semiconductor light emitting device of the comparative example. As shown in FIGS. 11 and 13, in the semiconductor light emitting device of the comparative example, the PL intensity ratio at the laser beam peak position was 0.84, whereas in the semiconductor light emitting device 1 according to Example 1, the PL intensity ratio was 0.84. , 0.02, as shown in FIGS. 11 and 14. Here, the intensity of PL is considered to correspond to the magnitude of light absorption. Therefore, in the semiconductor light emitting device 1 according to Example 1, absorption of laser light in the active layer 40 can be reduced more than in the semiconductor light emitting device of the comparative example. As a result, as shown in FIG. 11, the semiconductor light emitting device 1 according to Example 1 has higher output saturation starting point optical output, output saturation starting point current density, and slope efficiency than the semiconductor light emitting device of the comparative example. I can do it.

As shown in FIG. 11, the same characteristics as the semiconductor light emitting device 1 according to Example 1 can be obtained in each of the semiconductor light emitting devices 1 according to Examples 2 to 5. Here, the relationship between the output saturation start point and slope efficiency of the semiconductor light emitting device 1 according to each example and the semiconductor light emitting device of the comparative example, and the PL-laser light energy difference will be explained using FIGS. 15 and 16. explain. FIG. 15 is a graph showing the relationship between the optical output at the output saturation start point of the semiconductor light emitting device 1 according to each example and the semiconductor light emitting device of the comparative example and the PL-laser light energy difference. FIG. 16 shows the relationship between the slope efficiency and the PL-laser light energy difference when the optical output of the semiconductor light emitting device 1 according to each example and the semiconductor light emitting device of the comparative example is 0.5 W or more and 1.0 W or less. This is a graph showing. In FIGS. 15 and 16, black circles indicate data for each example, and black squares indicate data for a comparative example. Here, the range of optical output from 0.5 W to 1.0 W includes a high output region where the slope efficiency decreases in the comparative example, but in this embodiment, the output does not reach saturation and the slope This is an area where efficiency is stable.

As shown in FIGS. 15 and 16, in the semiconductor light emitting device of the comparative example, the PL-laser light energy difference is less than 0.050 eV, whereas in the semiconductor light emitting device 1 according to each example, the PL - The laser beam energy difference is 0.050 eV or more. More specifically, in the semiconductor light emitting device 1 of each example, the peak photon energy of the PL of the active layer 40 is higher than the peak photon energy of the laser beam by 0.050 eV or more. Thereby, as described above, absorption of laser light in the active layer 40 can be reduced, so as shown in FIGS. 15 and 16, the optical output and slope efficiency at the output saturation start point can be increased. Specifically, the optical output at the start point of output saturation can be set to 0.7 W or more, and the slope efficiency can be set to 0.7 W/A or more. In other words, the optical output increases linearly with respect to the injected current at least in a range where the optical output is 0.5 W or more and 0.7 W or less. Further, in this case, the current density at the output saturation starting point is 60 kA/mm ² or more.

In the semiconductor light emitting device 1 having the above characteristics, high output can be achieved. In each of the examples, it has been confirmed through experiments that continuous oscillation for at least 100 hours or more is possible with an optical output of 1 W at room temperature.

It was also confirmed that the larger the PL-laser light energy difference, the more the output characteristics such as the output saturation start point and slope efficiency tended to improve.

Further, in the semiconductor light emitting device 1 according to the present embodiment, the peak photon energy of the PL of the active layer 40 may be higher than the peak photon energy of the laser light by 0.103 eV or more. Thereby, the slope efficiency at the output saturation starting point can be further improved. Specifically, the slope efficiency can be set to 0.75 W/A or more. Further, the peak photon energy of the PL of the active layer 40 may be higher than the peak photon energy of the laser beam by 0.111 V or more. Thereby, the optical output and slope efficiency at the start point of output saturation can be further increased. Specifically, the optical output at the start point of output saturation can be 1.4 W or more, and the slope efficiency can be 1.1 W/A or more. Accordingly, even higher output of the semiconductor light emitting device 1 can be realized. In these cases, the current density at the start point of output saturation may be 78 kA/mm ² or more.

Furthermore, in the semiconductor light emitting device 1 according to the present embodiment, the difference between the peak photon energy of PL of the active layer 40 and the peak photon energy of the laser beam may be 0.250 eV or less. Thereby, gain can be reliably obtained in the active layer 40 of the semiconductor light emitting device 1.

Further, in the semiconductor light emitting device 1 according to the present embodiment, as shown in FIG. 11, in the PL spectrum of the active layer 40, the PL intensity at the peak photon energy of the laser beam is 40% of the peak intensity of the PL spectrum. It may be the following. Thereby, the absorption of laser light in the active layer 40 can be reduced, so that the optical output at the start point of output saturation can be increased. Note that when the PL-laser light energy difference is 0.050 eV, the PL intensity at the peak photon energy of the laser light is PL It was about 40% of the peak intensity of the spectrum.

Furthermore, in the semiconductor light emitting device 1 according to the present embodiment, as shown in FIG. 11, in the PL spectrum of the active layer 40, the PL intensity at the peak photon energy of the laser beam is 8% of the peak intensity of the PL spectrum. It may be the following. Thereby, the absorption of laser light in the active layer 40 can be further reduced, so that the optical output at the start point of output saturation can be further increased.

Further, in the semiconductor light emitting device 1 according to the present embodiment, when the peak photon energy of the laser light is 3.1 eV or more as in each example, the effect of the semiconductor light emitting device 1 according to the present embodiment is is more pronounced. That is, when the peak photon energy is large, the energy per photon is large, so the effect of heat generation due to light absorption is large. In particular, when the peak photon energy of the laser beam is 3.1 eV or more, the effect of reducing light absorption of the semiconductor light emitting device 1 according to this embodiment becomes remarkable. Therefore, it is also possible to suppress optical damage to the semiconductor light emitting device 1 due to light absorption.

Next, the relationship between the spontaneous emission light of the semiconductor light emitting device 1 according to this embodiment and the spectrum of PL will be explained using FIGS. 17 to 22. 17, FIG. 18, FIG. 19, and FIG. 20 are graphs showing spontaneous emission spectra and PL spectra of semiconductor light emitting devices according to Comparative Example, Example 1, Example 2, and Example 5, respectively. be. In FIGS. 17 to 20, the spontaneous emission spectrum is shown by a solid line, and the PL spectrum is shown by a broken line. FIG. 21 is a graph showing the relationship between the light output at the output saturation start point of the semiconductor light emitting device 1 according to each example and the semiconductor light emitting device of the comparative example and the PL-spontaneous emission light energy difference. FIG. 22 shows the relationship between the slope efficiency and the PL-Spontaneous emission light energy difference when the optical output of the semiconductor light emitting device 1 according to each example and the semiconductor light emitting device of the comparative example is 0.5 W or more and 1.0 W or less. This is a graph showing. In FIGS. 21 and 22, black circles indicate data of each example, and black squares indicate data of a comparative example.

As shown in FIGS. 17, 21, and 22, in the semiconductor light emitting device of the comparative example, the PL-Spontaneous emission light energy difference is less than 0.070 eV, whereas as shown in FIGS. Thus, in the semiconductor light emitting devices 1 according to Examples 1, 2, and 5, the PL-spontaneous emission energy difference is 0.070 eV or more. More specifically, in the semiconductor light emitting device 1 according to each example, the peak photon energy of PL of the active layer 40 is higher than the peak photon energy of spontaneous emission by 0.070 eV or more. The semiconductor light emitting devices 1 according to Examples 3 and 4 also have the same characteristics as the semiconductor light emitting device 1 according to Example 2, as shown in FIG.

The peak photon energy of the laser beam of a semiconductor light emitting device changes depending on the conditions of the resonator, and if it becomes larger than the peak photon energy of the spontaneous emission light within the gain region (photon energy range where gain can be obtained) of the spontaneous emission light. It is known that there may be cases where the In the semiconductor light emitting device 1 according to each example, the peak photon energy of PL of the active layer 40 is higher than the peak photon energy of spontaneous emission by 0.070 eV or more. For this reason, in the semiconductor light emitting device 1 according to the present embodiment, even if the oscillation wavelength deviates from the target wavelength depending on the conditions of the resonator, the difference in peak photon energy between the PL and the laser beam can be reduced. Since a sufficiently large amount can be ensured, absorption of laser light in the active layer 40 can be reduced. Therefore, the optical output at the start point of output saturation can be increased.

Furthermore, in the semiconductor light emitting device 1 according to the present embodiment, the peak photon energy of PL of the active layer 40 may be higher than the peak photon energy of spontaneous emission by 0.090 eV or more. Thereby, the optical output at the output saturation start point and the slope efficiency can be further increased. Accordingly, even higher output of the semiconductor light emitting device 1 can be realized.

Furthermore, in the semiconductor light emitting device 1 according to the present embodiment, the difference between the peak photon energy of PL of the active layer 40 and the peak photon energy of spontaneous emission light may be 0.250 eV or less. Thereby, gain can be reliably obtained in the active layer 40 of the semiconductor light emitting device 1.

Here, the configuration of the semiconductor light emitting device 1 that can obtain the characteristics described above will be explained. In this embodiment, as shown in FIG. 6, the difference in band gap energy between barrier layers 41 and 43 and well layer 42 is 0.140 eV or less. Although the detailed mechanism has not been elucidated, when the difference in band gap energy between each barrier layer and the well layer 42 is small as in the semiconductor light emitting device 1 according to the present embodiment, carriers injected into the well layer 42 A portion of the light passes through each barrier layer and flows into the first light guide layer 61 or the second light guide layer 62. It is estimated that the carriers flowing into each optical guide layer shift the PL spectrum of the active layer 40 to the higher energy side.

Further, in this embodiment, as shown in FIG. 6, the difference in band gap energy between the first light guide layer 61 and the barrier layer 41 closest to the first light guide layer 61 is less than 0.080 eV. be. Further, the difference in band gap energy between the second optical guide layer 62 and the barrier layer 43 closest to the second optical guide layer 62 is less than 0.080 eV. In this way, by reducing the bandgap energy between each light guide layer and the barrier layer closest to the light guide layer, the carriers that have flowed out into the light guide layer over the barrier can flow back into the well layer 42. It is possible to return.

Further, like the semiconductor light emitting device 1 according to Examples 2 to 4, the semiconductor light emitting device 1 according to the present embodiment is arranged above the barrier layer 43 closest to the second cladding layer 50, and the barrier layer It may further include an electronic block layer in contact with 43. Electrons injected into the well layer 42 of the semiconductor light emitting device 1 have a smaller effective mass than holes, so they easily exceed the barrier layer 43. Therefore, more carriers cross the barrier layer 43 close to the second cladding layer 50, which is a P-type cladding layer, than holes cross the barrier layer 41 close to the first cladding layer 30. Therefore, the semiconductor light emitting device 1 according to Examples 2 to 4 includes an electron block layer 70 disposed above the barrier layer 43 and in contact with the barrier layer 43. As a result, a region having a lower band gap energy than the barrier layer 43 and the electron block layer 70 is not formed between the barrier layer 43 and the electron block layer 70. Therefore, electrons that have passed through the barrier layer 43 easily return to the well layer 42. Thereby, the probability of recombination of electrons and holes in regions other than the well layer 42 can be reduced, so that the luminous efficiency (and slope efficiency, etc.) of the semiconductor light emitting device 1 can be increased.

Further, as in the barrier layer 43 and the second light guide layer 62 of the semiconductor light emitting device 1 according to Examples 1 and 5, the adjacent barrier layers 43 and the second light guide layer 62 have the same composition. If so, these may be regarded as one barrier layer. In this case, in the semiconductor light emitting device 1 according to Examples 1 and 5, it can be considered that the electron block layer is in contact with the barrier layer that is a combination of the barrier layer 43 and the second light guide layer 62. . Therefore, in the semiconductor light emitting devices 1 according to Examples 1 and 5, the same effects due to the electron blocking layer 70 as in the semiconductor light emitting devices 1 according to Examples 2 to 4 can be obtained.

Further, the semiconductor light emitting device 1 according to the present embodiment includes a first optical guide layer 61 disposed between the first cladding layer 30 and the active layer 40 and a first optical guide layer 61 disposed between the first cladding layer 30 and the active layer 40 and The well layer 42 may have at least one of the second light guide layers 62 disposed therebetween, and the thickness of the well layer 42 may be 17.5 nm or more.

The synergistic effect of the thick well layer 42 and the presence of carriers in each optical guide layer makes it possible to make the PL spectrum 0.050 eV larger than the peak photon energy of the laser beam. Although the active layer 40 has a single well layer 42 in each embodiment, it may have a plurality of well layers. That is, the active layer 40 may have a multiple quantum well structure. In this case, the total thickness of the plurality of well layers may be 17.5 nm.

Further, as in the semiconductor light emitting device 1 according to Example 5, each barrier layer is made of Al _z Ga _1-z N (0<z<1), and the well layer 42 is made of Al _x In _y Ga _{1-x -y} N (0<x<1, 0<y<1). Thereby, the same PL-laser light energy difference and PL-spontaneous emission light energy difference as in the case where the well layer 42 is made of InGaN as in the semiconductor light emitting device 1 according to Examples 1 to 4 can be obtained. Furthermore, in the semiconductor light emitting device 1 according to Example 5, the optical output at the start point of output saturation and the slope efficiency can be increased compared to the semiconductor light emitting devices 1 according to Examples 1 to 4.

Note that when the active layer 40 has a multiple quantum well structure, three or more barrier layers are made of AlzGa1-zN (0<z<1), and two or more well layers are made of AlxInyGa1-xyN (0 <x<1, 0<y<1). Also in this case, the same effect as in the case of a single quantum well structure (for example, Example 5) can be obtained.

(Variations, etc.)
The semiconductor light emitting device according to the present disclosure has been described above based on each example of the embodiment, but the present disclosure is not limited to each example of the above embodiment.

For example, in each of the above embodiments, an example was shown in which the semiconductor light emitting device 1 is a semiconductor laser device, but the semiconductor light emitting device 1 is not limited to a semiconductor laser device. For example, the semiconductor light emitting device according to the present disclosure includes an active layer 40, and the peak photon energy of PL of the active layer 40 is 0.070 eV higher than the peak photon energy of spontaneous emission light emitted from the semiconductor light emitting device into which current is injected. It may be higher than that. The semiconductor light emitting device according to the present disclosure may be, for example, a superluminescent diode.

The semiconductor light emitting device 1 according to each of the above embodiments includes one second light guide layer 62 between the active layer 40 and the second cladding layer 50, but may include two or more second light guide layers 62. Good too. For example, the semiconductor light emitting device according to the present disclosure includes a second optical guide layer 62 disposed between the active layer 40 and the electron block layer 70 and a second light guide layer disposed between the electron block layer 70 and the second cladding layer 50. A second light guide layer 62 may be provided. In this case, the configurations of each second light guide layer 62 may be different from each other.

Although the active layer 40 of the semiconductor light emitting device 1 according to each of the above embodiments has a single quantum well structure, it may have a multiple quantum well structure. That is, it may have a structure in which three or more barrier layers and two or more well layers are alternately stacked.

Furthermore, in the embodiments described above, the well layer 42 was made of InGaN or AlInGaN, but the configuration of the well layer 42 is not limited to this. The well layer 42 may be made of GaN, for example.

In addition, the embodiments and modifications described above may be modified in various ways that those skilled in the art may think of, and the components and functions of the embodiments and modifications described above may be arbitrarily modified without departing from the spirit of the present disclosure. The present disclosure also includes forms realized by combining.

The semiconductor light emitting device of the present disclosure can be used, for example, as a high output and highly efficient light source for laser processing.

1 Semiconductor

light emitting device

1F, 1R end surface 10 substrate 21 base layer 22 crack prevention layer 30 first cladding layer 40

active layer

41, 43 barrier layer 42 well layer 50 second cladding layer 50R ridge 50T groove 60 light guide layer 61 first light Guide layer 62 Second optical guide layer 70 Electronic block layer 80 Insulating layer 91 Upper electrode 92 Lower electrode

Claims

A semiconductor light emitting device,
A substrate and
a first cladding layer of a first conductivity type disposed above the substrate;
an active layer disposed above the first cladding layer;
a second cladding layer disposed above the active layer and having a second conductivity type different from the first conductivity type;
a light guide layer disposed between the first cladding layer and the second cladding layer,
The peak photon energy of photoluminescence of the active layer is higher than the peak photon energy of laser light emitted from the semiconductor light emitting element into which current is injected by 0.050 eV or more.
A semiconductor light emitting device,
A substrate and
a first cladding layer of a first conductivity type disposed above the substrate;
an active layer disposed above the first cladding layer;
a second cladding layer disposed above the active layer and having a second conductivity type different from the first conductivity type;
a light guide layer disposed between the first cladding layer and the second cladding layer,
In the photoluminescence spectrum of the active layer, the intensity of the photoluminescence at the peak photon energy of the laser light emitted from the semiconductor light-emitting element into which current is injected is 40% or less of the peak intensity of the spectrum.Semiconductor light-emitting element .
A semiconductor light emitting device comprising an active layer,
The peak photon energy of photoluminescence of the active layer is higher than the peak photon energy of spontaneous emission light emitted from the semiconductor light emitting device into which current is injected by 0.070 eV or more. A semiconductor light emitting device.
A substrate and
a first cladding layer of a first conductivity type disposed between the substrate and the active layer;
a second cladding layer disposed above the active layer and having a second conductivity type different from the first conductivity type;
The semiconductor light emitting device according to claim 3, further comprising a light guide layer disposed between the first cladding layer and the second cladding layer.
The semiconductor light emitting device according to any one of claims 1, 2, and 4, wherein the laser light emitted from the semiconductor light emitting device has a peak photon energy of 3.1 eV or more.
The semiconductor light emitting device according to any one of claims 1, 2, 4, and 5, wherein the light output of the semiconductor light emitting device at an output saturation starting point is 0.7 W or more.
The semiconductor light emitting device according to any one of claims 1, 2, 4, and 5, wherein the current density at the start point of output saturation of the semiconductor light emitting device is 60 kA/mm 2 or more.
The active layer has a quantum well structure in which two or more barrier layers and one or more well layers are alternately stacked,
The difference in band gap energy between each of the two or more barrier layers and each of the one or more well layers is 0.140 eV or less, according to any one of claims 1, 2, and 4 to 7. Semiconductor light emitting device.
The active layer has a quantum well structure in which two or more barrier layers and one or more well layers are alternately stacked,
The light guide layer includes a first light guide layer disposed between the first cladding layer and the active layer, and a second light guide disposed between the active layer and the second cladding layer. at least one of the layers;
Each of the first light guide layer and the second light guide layer has a band gap energy smaller than the two or more barrier layers and a band gap energy larger than the one or more well layers,
The difference in band gap energy between the first light guide layer and the barrier layer closest to the first light guide layer among the two or more barrier layers is less than 0.080 eV;
A difference in band gap energy between the second light guide layer and the barrier layer closest to the second light guide layer among the two or more barrier layers is less than 0.080 eV. 7. The semiconductor light emitting device according to any one of 7.
further comprising an electron blocking layer disposed above the barrier layer closest to the second cladding layer among the two or more barrier layers and in contact with the barrier layer,
The semiconductor light emitting device according to claim 9, wherein the light guide layer includes the first light guide layer.
The active layer has a quantum well structure in which two or more barrier layers and one or more well layers are alternately stacked,
The light guide layer includes a first light guide layer disposed between the first cladding layer and the active layer, and a second light guide disposed between the active layer and the second cladding layer. at least one of the layers;
8. The semiconductor light emitting device according to claim 1, wherein the total thickness of the one or more well layers is 17.5 nm or more.
The active layer has a quantum well structure in which two or more barrier layers and one or more well layers are alternately stacked,
The two or more barrier layers are made of Al z Ga 1-z N (0<z<1),
The one or more well layers are made of Al x In y Ga 1-xy N (0<x<1, 0<y<1) according to any one of claims 1, 2, and 4 to 7. semiconductor light emitting device.
A semiconductor light emitting device,
A substrate and
a first cladding layer of a first conductivity type disposed above the substrate;
an active layer disposed above the first cladding layer;
a second cladding layer disposed above the active layer and having a second conductivity type different from the first conductivity type;
a light guide layer disposed between the first cladding layer and the second cladding layer,
The active layer has a quantum well structure in which two or more barrier layers and one or more well layers are alternately stacked,
The difference in band gap energy between each of the two or more barrier layers and each of the one or more well layers is 0.140 eV or less,
The light guide layer includes a first light guide layer disposed between the first cladding layer and the active layer, and a second light guide disposed between the active layer and the second cladding layer. at least one of the layers;
Each of the first light guide layer and the second light guide layer has a band gap energy smaller than the two or more barrier layers and a band gap energy larger than the one or more well layers,
The difference in band gap energy between the first light guide layer and the barrier layer closest to the first light guide layer among the two or more barrier layers is less than 0.080 eV;
The difference in band gap energy between the second optical guide layer and the barrier layer closest to the second optical guide layer among the two or more barrier layers is less than 0.080 eV. A semiconductor light emitting device.
further comprising an electron blocking layer disposed above the barrier layer closest to the second cladding layer among the two or more barrier layers and in contact with the barrier layer,
The semiconductor light emitting device according to claim 13, wherein the light guide layer includes the first light guide layer.
The semiconductor light emitting device according to claim 13 or 14, wherein the total thickness of the one or more well layers is 17.5 nm or more.
The two or more barrier layers are made of Al z Ga 1-z N (0<z<1),
The semiconductor light emitting device according to any one of claims 13 to 15, wherein the one or more well layers are made of Al x In y Ga 1-xy N (0<x<1, 0<y<1). .
The semiconductor light emitting device according to any one of claims 13 to 16, wherein the peak photon energy of the laser light emitted from the semiconductor light emitting device is 3.1 eV or more.
The semiconductor light emitting device according to any one of claims 13 to 17, wherein the light output of the semiconductor light emitting device at the start point of output saturation is 0.7 W or more.
The semiconductor light emitting device according to any one of claims 13 to 18, wherein the current density at the start point of output saturation of the semiconductor light emitting device is 60 kA/mm 2 or more.