Semiconductor light-emitting element

Abstract

A semiconductor light emitting element (1) is provided with a substrate (10), a first cladding layer (30) of a first conductivity type disposed above the substrate (10), an active layer (40) disposed above the first cladding layer (30), a second cladding layer (50) of a second conductivity type different from the first conductivity type disposed above the active layer (40), and a light guide layer (60) disposed 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 0.050 eV or more higher than the peak photon energy of the laser light emitted from the semiconductor light-emitting element (1) into which the current has been injected.

Description

Technical Field

[0001] The present disclosure relates to a semiconductor light emitting element. Background Art

[0002] Conventionally, semiconductor light-emitting elements such as semiconductor laser elements that emit light from an active layer are known (Patent Document 1, etc.). The semiconductor light-emitting element described in Patent Document 1 includes an active layer having a quantum well structure, wherein the quantum well structure includes a well layer composed of InGaN. The semiconductor laser element described in Patent Document 1 performs laser oscillation near the peak wavelength of the photoluminescence (PL) spectrum of the active layer (i.e., a wavelength region where high optical gain is obtained).

[0003] Prior art literature

[0004] Patent Literature

[0005] Patent Document 1: Japanese Patent Application Publication No. 2009-252861 Summary of the invention

[0006] Problems to be solved by the invention

[0007] 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 element decreases. Furthermore, the temperature of the active layer rises due to the energy of the absorbed laser light, and thermal saturation and COD (Catastrophic Optical Damage) of light output saturation may occur.

[0008] Regarding the COD caused by the absorption of laser light near the resonator end face of the semiconductor light-emitting element, there is also a known countermeasure for reducing the absorption of laser light by increasing the band gap energy of the active layer near the resonator end face. In this way, the COD near the resonator end face can be suppressed, but the absorption of laser light cannot be reduced outside the vicinity of the resonator end face. Therefore, the suppression effect of thermal saturation brought about by this countermeasure is low.

[0009] The present disclosure is to solve such a problem, and an object of the present disclosure is to provide a semiconductor light emitting element capable of reducing light absorption in an active layer.

[0010] Means used to solve problems

[0011] In order to solve the above-mentioned problems, a technical solution of a semiconductor light-emitting element disclosed in the present invention comprises: a substrate; a first cladding layer of a first conductivity type, arranged above the above-mentioned substrate; an active layer, arranged above the above-mentioned first cladding layer; a second cladding layer of a second conductivity type different from the above-mentioned first conductivity type, arranged above the above-mentioned active layer; and a light-guiding layer, arranged between the above-mentioned first cladding layer and the above-mentioned second cladding layer; the peak photon energy of the photoluminescence of the above-mentioned active layer is higher than the peak photon energy of the laser emitted from the above-mentioned semiconductor light-emitting element into which current is injected by more than 0.050eV.

[0012] In order to solve the above-mentioned problems, another technical solution of the semiconductor light-emitting element disclosed in the present invention comprises: a substrate; a first cladding layer of a first conductivity type, arranged above the above-mentioned substrate; an active layer, arranged above the above-mentioned first cladding layer; a second cladding layer of a second conductivity type different from the above-mentioned first conductivity type, arranged above the above-mentioned active layer; and a light-guiding layer, arranged between the above-mentioned first cladding layer and the above-mentioned second cladding layer; in the photoluminescence spectrum of the above-mentioned active layer, the intensity of the above-mentioned photoluminescence at the peak photon energy of the laser emitted from the above-mentioned semiconductor light-emitting element to which current is injected is less than 40% of the peak intensity of the above-mentioned spectrum.

[0013] In order to solve the above problems, another technical solution of the semiconductor light emitting element disclosed in the present invention is a semiconductor light emitting element having an active layer, wherein the peak photon energy of the photoluminescence of the active layer is 0.070 eV or more higher than the peak photon energy of the spontaneous emission light emitted from the semiconductor light emitting element to which current is injected.

[0014] In order to solve the above-mentioned problems, another technical solution of the semiconductor light-emitting element disclosed in the present invention comprises: a substrate; a first cladding layer of a first conductivity type, arranged above the above-mentioned substrate; an active layer, arranged above the above-mentioned first cladding layer; a second cladding layer of a second conductivity type different from the above-mentioned first conductivity type, arranged above the above-mentioned active layer; and a light-guiding layer, arranged between the above-mentioned first cladding layer and the above-mentioned second cladding layer; the above-mentioned 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 above-mentioned two or more barrier layers and each of the above-mentioned one or more well layers is less than 0.140 eV; the above-mentioned light-guiding layer The layer comprises at least one of a first light-guiding layer arranged between the first cladding layer and the active layer and a second light-guiding layer arranged between the active layer and the second cladding layer; the first light-guiding layer and the second light-guiding layer each have a smaller band gap energy than the two or more barrier layers, and a larger band gap energy than the one or more well layers; the difference in band gap energy between the first light-guiding layer and the barrier layer closest to the first light-guiding layer among the two or more barrier layers is less than 0.080 eV; the difference in band gap energy between the second light-guiding layer and the barrier layer closest to the second light-guiding layer among the two or more barrier layers is less than 0.080 eV.

[0015] Effects of the Invention

[0016] According to the present disclosure, it is possible to provide a semiconductor light emitting element capable of reducing light absorption in an active layer. BRIEF DESCRIPTION OF THE DRAWINGS

[0017] Figure 1 It is a schematic plan view showing the overall structure of a semiconductor light emitting element according to an embodiment.

[0018] Figure 2 It is a schematic cross-sectional view showing the overall structure of a semiconductor light emitting element according to an embodiment.

[0019] Figure 3 This is a graph showing an example of a PL spectrum of a semiconductor light emitting element according to an embodiment.

[0020] Figure 4 This is a drawing showing an example of a PL spectrum of a semiconductor light emitting element in which an active layer is removed from the semiconductor light emitting element according to the embodiment.

[0021] Figure 5 This is a graph showing an example of a PL spectrum of an active layer according to an embodiment.

[0022] Figure 6 The diagrams show the layer structures of the semiconductor light emitting elements of the embodiments.

[0023] Figure 7This is a schematic cross-sectional view showing the structure of an active layer of the semiconductor light emitting element of Example 1.

[0024] Figure 8 This is a drawing schematically showing the band gap energy distribution in the stacking direction of the semiconductor light emitting element of Example 1.

[0025] Fig. 9 This is a drawing schematically showing the band gap energy distribution in the stacking direction of the semiconductor light emitting element of Example 2.

[0026] Fig.10 This is a drawing schematically showing the band gap energy distribution in the stacking direction of the semiconductor light emitting element of Example 4.

[0027] Fig.11 It is a diagram showing the characteristics of each example of the implementation mode.

[0028] Fig. 12A This is a graph showing the relationship between the injection current and the light output of the semiconductor light emitting element of Example 5.

[0029] Fig. 12B This is a graph showing the relationship between the light output of the semiconductor light emitting element of Example 5 and the ratio of the light output to the input power.

[0030] Fig.13 It is a graph showing the laser spectrum and PL spectrum of the semiconductor light emitting element of the comparative example.

[0031] Fig.14 It is a drawing showing the laser spectrum and PL spectrum of the semiconductor light emitting element of Example 1.

[0032] Fig.15 It is a graph showing the relationship between the light output and the PL-laser energy difference at the output saturation starting point of the semiconductor light emitting element of each example and the semiconductor light emitting element of the comparative example.

[0033] Fig.16 It is a graph showing the relationship between the slope efficiency and the PL-laser energy difference when the optical output of the semiconductor light emitting element of each example and the semiconductor light emitting element of the comparative example is 0.5 W or more and 1.0 W or less.

[0034] Fig.17 It is a graph showing the spontaneous emission spectrum and PL spectrum of the semiconductor light emitting element of the comparative example.

[0035] Fig.18 It is a graph showing the spontaneous emission spectrum and PL spectrum of the semiconductor light emitting element of Example 1.

[0036] Fig.19It is a drawing showing the spontaneous emission spectrum and PL spectrum of the semiconductor light emitting element of Example 2.

[0037] Fig. 20 It is a drawing showing the spontaneous emission spectrum and PL spectrum of the semiconductor light emitting element of Example 5.

[0038] Fig.21 It is a graph showing the relationship between the light output and the PL-spontaneous emission light energy difference at the output saturation starting point of the semiconductor light emitting element of each example and the semiconductor light emitting element of the comparative example.

[0039] Fig. 22 It is a graph showing the relationship between the slope efficiency and the PL-laser energy difference when the optical output of the semiconductor light emitting element of each example and the semiconductor light emitting element of the comparative example is 0.5 W or more and 1.0 W or less. DETAILED DESCRIPTION

[0040] Hereinafter, the embodiments of the present disclosure will be described with reference to the accompanying drawings. In addition, the embodiments described below all represent a specific example of the present disclosure. Therefore, the numerical values, shapes, materials, components, and the configuration positions and connection forms of the components shown in the following embodiments are taken as examples and are not intended to limit the present disclosure.

[0041] In addition, each figure is a schematic diagram and does not necessarily illustrate strictly. Therefore, the scales and the like in each figure are not necessarily the same. In addition, in each figure, the same reference numerals are given to substantially the same structure, and repeated descriptions are omitted or simplified.

[0042] In addition, in this specification, the terms "above" and "below" do not refer to above (vertically above) and below (vertically below) in absolute spatial identification, but are used as terms defined by relative positional relationships based on the stacking order in the stacking structure. In addition, the terms "above" and "below" are not only applicable to the case where two components are arranged at a distance from each other and there is another component between the two components, but also to the case where two components are arranged in a state of being in contact with each other.

[0043] (Implementation Method)

[0044] A semiconductor light emitting element according to an embodiment will be described.

[0045] [1. Basic structure]

[0046] use Figure 1 The basic structure of the semiconductor light emitting element of this embodiment is described. Figure 1 and Figure 21 and 2 are schematic top views and cross-sectional views showing the basic structure of the semiconductor light emitting element 1 of the present embodiment. In addition, mutually orthogonal X-axis, Y-axis and Z-axis are shown in each figure. The X-axis, Y-axis and Z-axis are right-handed orthogonal coordinate systems. The stacking direction of the semiconductor light emitting element 1 (i.e., the thickness direction of each layer of the semiconductor light emitting element 1) is parallel to the Z-axis direction, and the main propagation direction of light (laser) is parallel to the Y-axis direction.

[0047] The semiconductor light emitting element 1 is an element that emits light by current injection. In the present embodiment, the semiconductor light emitting element 1 is a semiconductor laser element that emits laser light with a peak wavelength of 400 nm or less (peak photon energy of 3.1 eV or less). Figure 1 As shown, the semiconductor light emitting element 1 has two end faces 1F and 1R forming a resonator. End face 1F is a front face from which laser light is emitted, and end face 1R is a rear face having a higher reflectivity than end face 1F. In addition, the semiconductor light emitting element 1 has a waveguide formed between end face 1F and end face 1R.

[0048] The resonator length of the semiconductor light emitting element 1, that is, the distance between the end faces 1F and 1R in the propagation direction of the laser (the Y-axis direction of each figure, that is, the resonance direction) is not particularly limited, and is 1200 μm in this embodiment. The semiconductor light emitting element 1 may also have a reflective film disposed at the end in the propagation direction of the laser. The reflective film is a film for adjusting the reflectivity of the end faces 1F and 1R, respectively. As the reflective film, a dielectric multilayer film or the like can be used.

[0049] like Figure 2 As shown, the semiconductor light emitting element 1 includes a substrate 10, a first cladding layer 30 disposed on the substrate 10, an active layer 40 disposed on the first cladding layer 30, a second cladding layer 50 disposed on the active layer 40, and a light guiding layer 60 disposed between the first cladding layer 30 and the second cladding layer 50. In the present embodiment, the semiconductor light emitting element 1 further includes a base layer 21 disposed between the substrate 10 and the first cladding layer 30, a crack prevention layer 22 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 on the second cladding layer 50, an upper electrode 91 disposed on the insulating layer 80, and a lower electrode 92 disposed on the lower surface of the substrate 10 (i.e., the main surface opposite to the main surface on which each semiconductor layer is stacked).

[0050] The substrate 10 is a plate-shaped member serving as a base of the semiconductor light emitting element 1. In the present embodiment, the first conductivity type is the N type.

[0051] The base layer 21 is a first conductivity type semiconductor layer disposed on the substrate 10. In the present embodiment, the base layer 21 is stacked on the main surface of the substrate 10.

[0052] The crack prevention layer 22 is a semiconductor layer of the first conductivity type disposed on the substrate 10. In the present embodiment, the crack prevention layer 22 is disposed on the base layer 21.

[0053] The first cladding layer 30 is a semiconductor layer of the first conductivity type 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 and the like is defined by a value obtained by dividing the value obtained by integrating the refractive index in the thickness direction of the layer by the thickness of the layer. In the present embodiment, the first cladding layer 30 is disposed above the crack prevention layer 22.

[0054] The active layer 40 is a light emitting layer disposed on the first cladding layer 30. In the present embodiment, the peak photon energy of PL of the active layer 40 is 0.050 eV or more higher than the peak photon energy of laser light emitted from the semiconductor light emitting element 1 into which current is injected.

[0055] Here, use Figure 3 to Figure 5 The measurement direction of the peak photon energy of PL of the active layer 40 is described. Figure 3 This is a graph showing an example of the PL spectrum of the semiconductor light emitting element 1 according to the present embodiment. Figure 4 This is a graph showing an example of a PL spectrum of the semiconductor light emitting element 1 according to the present embodiment in which the active layer 40 is removed. Figure 5 This is a graph showing an example of the PL spectrum of the active layer 40 according to the present embodiment. Figure 3 to Figure 5 The horizontal axis of each plot represents the photon energy corresponding to the wavelength of PL, and the vertical axis represents the standardized PL intensity.

[0056] In order to measure the PL spectrum of the active layer 40, first, the spectrum of the PL emitted from the semiconductor light emitting element 1 by optically exciting the semiconductor light emitting element 1 using a He-Cd laser with a wavelength of 325 nm is measured. For example, in GaN-based semiconductor laser elements, 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, since the band gap energy of the crack prevention layer 22 is lower than that of the base layer 21 and the first cladding layer 30, in the PL spectrum obtained by the above-mentioned measurement, Figure 3 As shown, it includes not only the PL of the active layer 40 but also the PL of the crack prevention layer 22. Therefore, the spectrum of PL emitted from the portion where the structure above the light guide layer 60 including the active layer 40 is removed from the semiconductor light emitting element 1 by optically exciting the portion using a He-Cd laser with a wavelength of 325 nm is measured ( Figure 4 ). By Figure 3 In the PL spectrum of the semiconductor light emitting element 1 shown in FIG. Figure 4The PL component of the crack prevention layer 22 shown is removed to obtain Figure 5 The PL spectrum of the active layer 40 is shown in FIG. Figure 4 The intensity of the spectrum shown is such that Figure 5 The spectrum after removal shown in FIG. 1 does not contain the peak of the PL spectrum of the crack prevention layer 22. Specifically, Figure 3 The peak intensity at the position near 3.31 eV is 0.91. In contrast, the intensity is adjusted so that Figure 4 The peak intensity of Figure 3 The spectral intensity is subtracted Figure 4 The spectral intensity obtained Figure 5 In the spectrum of , the peak around 3.31 eV is no longer seen.

[0057] When removing the active layer 40 from the semiconductor light emitting element 1, wet etching can be used, for example. Specifically, first, an aqua regia-based etchant is used to remove the upper electrode 91 and the lower electrode 92. Next, an etchant of a hydrofluoric acid-based etchant is used to remove the insulating layer 80. Next, the active layer 40 and the semiconductor layer disposed thereon are removed by reactive ion etching. For example, the first light guide layer 61 and the semiconductor layer disposed thereon may also be removed by reactive ion etching.

[0058] 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.

[0059] The second cladding layer 50 is a semiconductor layer of a second conductivity type different from the first conductivity type and arranged 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 guiding layer 60 and the electron blocking layer 70. The second conductivity type is P type.

[0060] In this embodiment, a ridge 50R extending in the light propagation direction (i.e., the Y-axis direction) is formed in the second cladding 50. In other words, two grooves 50T extending along the light propagation direction are formed on the upper surface of the second cladding 50, and the ridge 50R is formed between the two grooves 50T. The waveguide is formed along the ridge 50R. Figure 1 , the upper surface of the ridge 50R and the outline of the groove 50T are indicated by dotted 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.

[0061] The optical waveguide layer 60 is a semiconductor layer disposed between the first cladding layer 30 and the second cladding layer 50. The optical waveguide layer 60 includes at least one of a first optical waveguide layer 61 disposed between the first cladding layer 30 and the active layer 40 and a second optical waveguide layer 62 disposed between the active layer 40 and the second cladding layer 50. Figure 2 , an example is shown in which the optical waveguide layer 60 includes both the first optical waveguide layer 61 and the second optical waveguide layer 62. The first optical waveguide layer 61 and the second optical waveguide layer 62 each have a smaller band gap energy than the barrier layers 41 and 43 and a larger band gap energy than the well layer 42.

[0062] The electron blocking layer 70 is a semiconductor layer disposed between the active layer 40 and the second cladding layer 50. The electron blocking layer 70 is a semiconductor layer having a larger band gap energy than the second cladding layer 50. Thus, the electron blocking layer 70 functions as a barrier for electrons from the active layer 40 toward the second cladding layer 50, thereby confining the electrons in the active layer 40. Figure 2 In the example shown, the electron blocking layer 70 is disposed between the second light guiding layer 62 and the second cladding layer 50 .

[0063] The insulating layer 80 is an electrically insulating layer disposed on the second cladding layer 50. In the present embodiment, the insulating layer 80 is disposed in a region of the upper surface of the second cladding layer 50 other than the upper surface of the ridge 50R.

[0064] The upper electrode 91 is a conductive layer disposed above the second cladding layer 50. In this embodiment, the upper electrode 91 is used as an electrode for injecting current into the semiconductor light emitting element 1 through the opening of the insulating layer 80. The upper electrode 91 is disposed on at least a portion of the upper surface of the ridge 50R of the second cladding layer 50.

[0065] The lower electrode 92 is an electrode disposed on the lower surface of the substrate 10 , and is used as an electrode for injecting current into the semiconductor light emitting element 1 .

[0066] [2. Example]

[0067] use Figure 6 An example of the semiconductor light emitting element 1 according to the present embodiment will be described. Figure 6 It is a diagram showing the layer structure of each example of the semiconductor light emitting element 1 according to the present embodiment. Figure 6 The composition and film thickness of each layer of the semiconductor light emitting element 1 of each embodiment and the semiconductor light emitting element of the comparative example are described in Figure 6The difference in band gap energy between the barrier layer and the well layer, the difference in band gap energy (Eg) between the bottom barrier layer (the barrier layer closest to the first light guide layer 61) and the first light guide layer, and the difference in band gap 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. The detailed structures of the semiconductor light emitting element of the comparative example and the semiconductor light emitting element 1 of each embodiment are described below.

[0068] [2-1. Comparative Example]

[0069] Figure 6 The semiconductor light emitting element of the comparative example shown in the figure has a substrate, a base layer, a crack prevention layer, a first cladding layer, a first light guiding layer, an active layer, an electron blocking layer, a second light guiding layer, and a second cladding layer, similarly to the semiconductor light emitting element 1 of the present embodiment. Figure 6 Although not shown, the semiconductor light emitting element of the comparative example also includes an insulating layer, an upper electrode, and a lower electrode, similarly to the semiconductor light emitting element 1 of the present embodiment.

[0070] The substrate of the semiconductor light emitting element of the comparative example is an N-type GaN substrate to which Si is added as an impurity. The base layer is an N-type Al 0.02 Ga 0.98 N layer. The crack prevention layer is an N-type In 0.03 Ga 0.97 N layer. The first cladding layer is 540nm thick and contains 5×10 17 cm -3 Si N-type Al 0.065 Ga 0.935 N layer. The first light guide layer has a film thickness of 127 nm and a concentration of 5×10 17 cm -3 Si N-type Al 0.03 Ga 0.97 N layer and a 180nm thick undoped Al 0.02 Ga 0.98 N layers.

[0071] The active layer has a thickness of 7.5 nm and is undoped In 0.01 Ga 0.99 The N layer is the well layer, and the undoped Al layer with a thickness of 12 nm is arranged below the well layer. 0.05 Ga 0.95 The N layer, i.e. the barrier layer, and the 12 nm thick undoped Al layer disposed above the well layer 0.05 Ga 0.95 The N layer is the barrier layer. Figure 6As shown, in the active layer of the comparative example, the difference in bandgap energy between each barrier layer and the well layer is larger than 0.140 eV, unlike the active layer 40 of the present embodiment. The difference in bandgap energy between each barrier layer and the well layer of the active layer of the comparative example is 0.163 eV.

[0072] The second light guide layer is a P-type Al 0.02 Ga 0.98 N layer. The electron blocking layer is a P-type Al layer with a thickness of 5.5 nm. 0.36 Ga 0.64 N layer. The second cladding layer is a 660nm thick layer with a concentration of 8×10 18 cm -3 P-type Al of Mg 0.065 Ga 0.935 N layers.

[0073] In the semiconductor light-emitting element of the comparative example, the difference in band gap energy between the first light guiding layer and the barrier layer closest to the first light guiding layer among the barrier layers of the active layer is 0.080 eV, and the difference in band gap energy between the second light guiding layer and the barrier layer closest to the second light guiding layer among the barrier layers of the active layer is 0.053 eV.

[0074] [2-2. Example 1]

[0075] The semiconductor light emitting element 1 of the first embodiment includes a substrate 10, a base layer 21, a crack prevention layer 22, a first cladding layer 30, a first light guiding layer 61, an active layer 40, a second light guiding layer 62, an electron blocking layer 70, and a second cladding layer 50. The second light guiding layer 62 of the first embodiment is disposed between the active layer 40 and the electron blocking layer 70.

[0076] The substrate 10 , the base layer 21 , the crack prevention layer 22 , the first light guide layer 61 , and the second cladding layer 50 of the semiconductor light emitting element 1 of Example 1 have the same structure as those of the semiconductor light emitting element of the comparative example.

[0077] The first cladding layer 30 of Example 1 is 800 nm thick and contains 5×10 17 cm -3 Si N-type Al 0.065 Ga 0.935 N layers.

[0078] use Figure 7 The active layer 40 of the first embodiment will be described. Figure 7 FIG. 4 is a schematic cross-sectional view showing the structure of the active layer 40 of the semiconductor light emitting element 1 of Example 1. Figure 7 It is expressed in Figure 2 The cross section of the semiconductor light emitting element 1 at the same position. Figure 7As shown, the active layer 40 of Example 1 includes a barrier layer 41, a well layer 42 disposed on the barrier layer 41, and a barrier layer 43 disposed on the well layer 42. The barrier layer 41 is an undoped Al layer having a thickness of 12 nm. 0.04 Ga 0.96 N layer. The well layer 42 is an undoped In layer with a thickness of 17.5 nm. 0.01 Ga 0.99 N layer. The barrier layer 43 is undoped Al 0.03 Ga 0.97 N layers. In addition, Figure 6 As shown, the barrier layer 43 and the second light guide layer 62 have the same composition (Al 0.03 Ga 0.97 N), the total thickness of the barrier layer 43 and the second light guide layer 62 is 130 nm. That is, in the 130 nm thick undoped Al layer disposed above the well layer 42, 0.03 Ga 0.97 In the N layer, a portion closer to the well layer 42 functions as the barrier layer 43 , and a portion farther from the well layer 42 functions as the second light guiding layer 62 .

[0079] The electron blocking layer 70 is a P-type Al layer with a thickness of 1.6 nm. 0.36 Ga 0.64 N layers.

[0080] use Figure 8 The band gap energy distribution of the semiconductor light emitting element 1 of Example 1 is described. Figure 8 This is a drawing schematically showing the band gap energy distribution in the stacking direction of the semiconductor light emitting element 1 of Example 1.

[0081] like Figure 8 (and Figure 6 ) shows that, in the semiconductor light emitting element 1 of Example 1, the difference in band gap energy between each barrier layer of the active layer 40 and the well layer 42 is less than 0.140 eV.

[0082] In addition, if Figure 6 As shown, in the semiconductor light emitting element 1 of Example 1, the difference in band gap energy between the first optical waveguide layer 61 and the barrier layer 41 is 0.053 eV. In addition, the second optical waveguide layer 62 and the barrier layer 43 have no difference in band gap energy because they have the same composition.

[0083] [2-3. Example 2]

[0084] The semiconductor light emitting element 1 of Example 2 is as follows Figure 6 As shown, the semiconductor light emitting element 1 of Example 1 is different mainly in the positional relationship between the electron blocking layer 70 and the second light guiding layer 62 and the composition of the first light guiding layer 61 .

[0085] The substrate 10, base layer 21 and anti-crack layer 22 of the semiconductor light emitting element 1 of Example 2 respectively have the same structures as the substrate 10, base layer 21 and anti-crack layer 22 of the semiconductor light emitting element 1 of Example 1 (and the semiconductor light emitting element of the comparative example). The first cladding layer 30, well layer 42 and electron blocking layer 70 of the semiconductor light emitting element 1 of Example 2 respectively have the same structures as the first cladding layer 30, well layer 42 and electron blocking layer 70 of the semiconductor light emitting element 1 of Example 1.

[0086] The first light guide layer 61 of Example 2 has a film thickness of 127 nm and contains a 5×10 17 cm -3 Si N-type Al 0.03 Ga 0.97 N layer and a 90nm thick undoped Al 0.03 Ga 0.97 The barrier layer 41 is an undoped Al layer with a thickness of 10 nm. 0.04 Ga 0.96 The barrier layer 43 is an undoped Al layer with a thickness of 20 nm. 0.03 Ga 0.97 The second optical guide layer 62 is a P-type Al layer with a thickness of 130 nm and is disposed above the electron blocking layer 70. 0.03 Ga 0.97 N layer. In the second light guide layer 62, a concentration of 3×10 18 cm -3 The second cladding layer 50 is a P-type Al with a film thickness of 450nm. 0.065 Ga 0.935 N layers.

[0087] use Fig. 9 The band gap energy distribution of the semiconductor light emitting element 1 of Example 2 is described. Fig. 9 This is a drawing schematically showing the band gap energy distribution in the stacking direction of the semiconductor light emitting element 1 of Example 2.

[0088] like Fig. 9 (and Figure 6 ), in the semiconductor light emitting element 1 of Example 2, the difference in band gap energy between each barrier layer of the active layer 40 and the well layer 42 is less than 0.140 eV. In addition, in Example 2, the difference in band gap energy between the barrier layer 41 and the first light guiding layer 61 is smaller than that in Example 1.

[0089] In addition, if Figure 6 As shown, in the semiconductor light emitting element 1 of Example 2, the difference in band gap energy between the first optical guiding layer 61 and the barrier layer 41 is 0.027 eV. In addition, the second optical guiding layer 62 and the barrier layer 43 have no difference in band gap energy because they have the same composition.

[0090] [2-4. Example 3]

[0091] The semiconductor light emitting element 1 of Example 3 is as follows Figure 6 As shown, the main difference from the semiconductor light emitting element 1 of Example 2 is that the impurity (Mg) concentration of the second light guiding layer 62 is low.

[0092] The substrate 10, base layer 21 and crack prevention layer 22 of the semiconductor light emitting element 1 of Example 3 respectively have the same structures as the substrate 10, base layer 21 and crack prevention layer 22 of the semiconductor light emitting element 1 of Example 2 (and the semiconductor light emitting element of the comparative example). The first cladding layer 30, first light guiding layer 61, well layer 42, barrier layer 43, electron blocking layer 70 and second cladding layer 50 of the semiconductor light emitting element 1 of Example 3 respectively have the same structures as the first cladding layer 30, first light guiding layer 61, well layer 42, barrier layer 43, electron blocking layer 70 and second cladding layer 50 of the semiconductor light emitting element 1 of Example 2.

[0093] The barrier layer 41 of Example 3 is the same as the barrier layer 41 of Example 1, which is an undoped Al layer with a thickness of 12 nm. 0.04 Ga 0.96 The second light guide layer 62 is a P-type Al layer with a thickness of 130 nm, similar to the second light guide layer 62 of Example 2. 0.03 Ga 0.97 N layer, but the impurity concentration is lower than that of the second light guide layer 62 of Example 2. The Mg concentration of the second light guide layer 62 of Example 3 is 2×10 18 cm -3 .

[0094] The band gap energy distribution of the semiconductor light emitting element 1 of Example 3 is the same as the band gap energy distribution of the semiconductor light emitting element 1 of Example 2. Figure 6 As shown, in the semiconductor light emitting element 1 of the third embodiment, similarly to the second embodiment, the difference in band gap energy between each barrier layer of the active layer 40 and the well layer 42 is 0.140 eV or less.

[0095] [2-5. Example 4]

[0096] The semiconductor light emitting element 1 of Example 4 is as follows Figure 6 As shown, the main difference from the semiconductor light emitting element 1 of Example 2 is the composition of the barrier layer 43 .

[0097] The substrate 10 and the base layer 21 of the semiconductor light emitting element 1 of Example 4 respectively have the same structures as the substrate 10 and the base layer 21 of the semiconductor light emitting element 1 of Example 2 (and the semiconductor light emitting element of the comparative example). The first cladding layer 30, the first light guiding layer 61, the well layer 42, the electron blocking layer 70, the second light guiding layer 62 and the second cladding layer 50 of the semiconductor light emitting element 1 of Example 4 respectively have the same structures as the first cladding layer 30, the first light guiding layer 61, the well layer 42, the electron blocking layer 70, the second light guiding layer 62 and the second cladding layer 50 of the semiconductor light emitting element 1 of Example 2.

[0098] The crack prevention layer 22 of Example 4 is an N-type In 0.04 Ga 0.96 N layer. The first light guide layer 61 has a film thickness of 127 nm and contains 5×10 17 cm -3 Si N-type Al 0.03 Ga 0.97 N layer and an 80nm thick undoped Al 0.03 Ga 0.97 The barrier layer 41 is an undoped Al layer with a thickness of 14 nm. 0.04 Ga 0.96 The barrier layer 43 is an undoped Al layer with a thickness of 10 nm. 0.04 Ga 0.96 N layers.

[0099] use Fig.10 The band gap energy distribution of the semiconductor light emitting element 1 of Example 4 is described. Fig.10 It is a drawing schematically showing the band gap energy distribution in the stacking direction of the semiconductor light emitting element 1 of Example 4.

[0100] like Fig.10 (and Figure 6 ), in the semiconductor light emitting element 1 of Example 4, as in Example 2, the difference in band gap energy between each barrier layer of the active layer 40 and the well layer 42 is less than 0.140 eV. In addition, in the semiconductor light emitting element 1 of Example 4, the band gap energy of the barrier layer 43 is greater than the band gap energy of the barrier layer 43 of Example 2.

[0101] In addition, if Figure 6 As shown, in the semiconductor light emitting element 1 of Example 4, the difference in band gap energy between the first optical guiding layer 61 and the barrier layer 41 is 0.027 eV. In addition, the difference in band gap energy between the second optical guiding layer 62 and the barrier layer 43 is also 0.027 eV.

[0102] [2-6. Example 5]

[0103] The semiconductor light emitting element 1 of Example 5 is as follows Figure 6 As shown, the main difference from the semiconductor light emitting element 1 of the first embodiment is that the well layer 42 is an AlInGaN layer.

[0104] The substrate 10, base layer 21, crack prevention layer 22 and second cladding layer 50 of the semiconductor light emitting element 1 of Example 5 respectively have the same structures as the substrate 10, base layer 21, crack prevention layer 22 and second cladding layer 50 of the semiconductor light emitting element 1 of Example 1 (and the semiconductor light emitting element of the comparative example). The first cladding layer 30, barrier layer 41 and electron blocking layer 70 of the semiconductor light emitting element 1 of Example 5 respectively have the same structures as the first cladding layer 30, barrier layer 41 and electron blocking layer 70 of the semiconductor light emitting element 1 of Example 1.

[0105] The first light guide layer 61 of Example 5 is similar to the first light guide layer 61 of Example 2, and has a film thickness of 127 nm and contains 5×10 17 cm -3 Si N-type Al 0.03 Ga 0.97 N layer and a 90nm thick P-type Al 0.03 Ga 0.97 N layer. The well layer 42 is an undoped Al layer with a thickness of 17.5 nm. 0.02 In 0.035 Ga 0.945 N layer. The barrier layer 43 is undoped Al 0.03 Ga 0.97 N layers. Figure 6 As shown, the barrier layer 43 and the second light guide layer 62 have the same composition (Al 0.03 Ga 0.97 N), the total thickness of the barrier layer 43 and the second light guide layer 62 is 70 nm. That is, the undoped Al layer with a thickness of 70 nm disposed above the well layer 42 0.03 Ga 0.97 In the N layer, a portion closer to the well layer 42 functions as the barrier layer 43 , and a portion farther from the well layer 42 functions as the second light guiding layer 62 .

[0106] The band gap energy distribution of the semiconductor light emitting element 1 of Example 5 is the same as the band gap energy distribution of the semiconductor light emitting element 1 of Example 1. Figure 6 As shown, in the semiconductor light emitting element 1 of Example 5, similarly 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.

[0107] [3. Characteristics and effects]

[0108] While comparing the above comparative examples with the embodiments, Figure 6 and Fig.11 The characteristics and effects of the semiconductor light emitting element 1 of this embodiment will be described. Fig.11 FIG. 1 is a diagram showing the characteristics of each example of the present embodiment. Fig.11 , the characteristics obtained by experiments of the semiconductor light emitting element 1 of each embodiment are shown together with the characteristics obtained by experiments of the semiconductor light emitting element of the comparative example. Fig.11 In the description, properties that were not measured at the time of filing the present application are described as “not measured”. Fig.11 The laser oscillation characteristics of each semiconductor light emitting element shown here represent the characteristics of a case where a continuous (CW) oscillation operation is performed at room temperature with a light output of 0.3 W.

[0109] Fig.11 The peak photon energy (peak position) and half-width (full width at half maximum) of the spontaneous emission light shown are values ​​obtained by measuring the emission spectrum of each semiconductor light emitting element injected with a current less than the oscillation threshold using a spectrum analyzer. Fig.11 The peak photon energy (peak position) and half-width (full width at half maximum) of the laser light shown are values ​​obtained by measuring the emission spectrum of each semiconductor light-emitting element injected with a current larger than the oscillation threshold using a spectrum analyzer.

[0110] Fig.11 The PL-laser energy difference shown is Fig.11 The difference between the peak photon energy of the PL spectrum measured by the above method and the peak photon energy of the laser is shown.

[0111] Fig.11 The PL-spontaneous emission energy difference shown is the difference between the peak photon energy of the PL spectrum measured by the above method and Fig.11 The difference in peak photon energy of the spontaneous emission is shown.

[0112] Fig.11 The PL intensity ratio at the laser peak position shown is a ratio of the PL intensity at the peak photon energy of the laser light emitted from the semiconductor light emitting element to which current is injected, to the peak PL intensity.

[0113] Fig.11 The PL intensity ratio at an energy side 0.050 eV lower than the PL peak position shown is a ratio of the PL intensity at a photon energy 0.050 eV lower than the peak photon energy in the PL spectrum to the peak PL intensity.

[0114] for Fig.11The slope efficiency and output saturation starting point shown are used as an example. Fig. 12A and Fig. 12B The characteristics of the semiconductor light emitting element 1 of the fifth embodiment shown will be described. Fig. 12A 1 is a graph showing the relationship between the injection current and the light output of the semiconductor light emitting element 1 of Example 5, wherein the I-L curve is represented by a solid line and the slope efficiency curve (the slope of the I-L curve) is represented by a dotted line. Fig. 12B 1 is a graph showing the relationship between the light output of the semiconductor light emitting element 1 of Example 5 and the ratio of the light output to the input power (ie, the wall plug efficiency WPE (wall plug efficiency)).

[0115] Slope efficiency is the increase in light output per unit increase in current and is related to Fig. 12A The slope of the I-L curve shown corresponds to the value. Fig.11 The slope efficiency for each light output range is shown in .

[0116] The output saturation starting point is equivalent to the inflection point where the slope of the I-L curve begins to decrease, such as Fig. 12A As shown in FIG. 1 , the light output at the output saturation starting point is 2.1 W (2100 mW). In addition, the output saturation starting point can also be Fig. 12B As shown, it is defined as the point where the ratio of light output to input power to the semiconductor light emitting element is maximum.

[0117] First, the relationship between the peak photon energy of the laser and the PL peak photon energy of the semiconductor light emitting element 1 of the present embodiment is compared with that of the comparative example. Fig.13 and Fig.14 Provide explanation. Fig.13 and Fig.14 Graphs showing the laser spectrum and PL spectrum of the semiconductor light emitting element of the comparative example and the semiconductor light emitting element 1 of Example 1, respectively. Fig.13 and Fig.14 In the figure, the laser spectrum is represented by a solid line, and the PL spectrum is represented by a dotted line.

[0118] like Fig.13 As shown, in the semiconductor light emitting element of the comparative example, the peak photon energy of the PL is 0.049 eV higher than the peak photon energy of the laser. In contrast, in the semiconductor light emitting element 1 of Example 1, the peak photon energy of the PL is 0.112 eV higher than the peak photon energy of the laser. Thus, in the semiconductor light emitting element 1 of Example 1, the PL-laser energy difference is greater than that of the semiconductor light emitting element of the comparative example. As a result, in the semiconductor light emitting element 1 of Example 1, the intensity of the PL at the peak photon energy of the laser becomes smaller than that of the semiconductor light emitting element of the comparative example. Fig.11 and Fig.13 As shown in FIG. 1 , in the semiconductor light emitting element of the comparative example, the PL intensity ratio at the laser peak position is 0.84, whereas in the semiconductor light emitting element 1 of the embodiment 1, Fig.11 and Fig.14 As shown in FIG. 1 , the intensity of PL corresponds to the magnitude of light absorption. Therefore, in the semiconductor light emitting element 1 of Example 1, the absorption of laser light in the active layer 40 can be reduced compared with the semiconductor light emitting element of the comparative example. Fig.11 As shown, in the semiconductor light emitting element 1 of Example 1, the output saturation starting point light output, the output saturation starting point current density and the slope efficiency can be improved compared with the semiconductor light emitting element of the comparative example.

[0119] like Fig.11 As shown, the semiconductor light emitting elements 1 of Examples 2 to 5 can also obtain the same characteristics as the semiconductor light emitting element 1 of Example 1. Fig.15 and Fig.16 The relationship between the output saturation starting point and slope efficiency of the semiconductor light emitting element 1 of each example and the semiconductor light emitting element of the comparative example and the PL-laser energy difference is described. Fig.15 It is a graph showing the relationship between the light output and the PL-laser energy difference at the output saturation starting point of the semiconductor light emitting element 1 of each example and the semiconductor light emitting element of the comparative example. Fig.16 This is a graph showing the relationship between the slope efficiency and the PL-laser energy difference when the light output of the semiconductor light emitting element 1 of each example and the semiconductor light emitting element of the comparative example is 0.5 W or more and 1.0 W or less. Fig.15 and Fig.16 In the figure, the black circle marks represent the data of each embodiment, and the black square marks represent the data of the comparative example. Here, regarding the light output range of 0.5W or more and 1.0W or less, the comparative example includes a high output region where the slope efficiency decreases, while in the present embodiment, the output does not reach saturation, and becomes a region where the slope efficiency is stable.

[0120] like Fig.15 and Fig.16 As shown, in the semiconductor light emitting element of the comparative example, the PL-laser energy difference is less than 0.050 eV, whereas in the semiconductor light emitting element 1 of each embodiment, the PL-laser energy difference is greater than 0.050 eV. More specifically, in the semiconductor light emitting element 1 of each embodiment, the peak photon energy of the PL of the active layer 40 is greater than the peak photon energy of the laser by 0.050 eV or more. As a result, as described above, the absorption of the laser in the active layer 40 can be reduced, so Fig.15 and Fig.16As shown, the light output and slope efficiency at the start point of output saturation can be improved. Specifically, the light output at the start point of output saturation can be made above 0.7W, and the slope efficiency can be made above 0.7W / A. In other words, at least in the range of light output being above 0.5W and below 0.7W, the light output increases linearly with respect to the injected current. In addition, in this case, the current density at the start point of output saturation is 60kA / mm 2 above.

[0121] The semiconductor light emitting element 1 having the above-described characteristics can achieve high output. In each example, it was confirmed through experiments that continuous oscillation can be performed for at least 100 hours at a light output of 1 W at room temperature.

[0122] In addition, it was confirmed that there is a tendency that the larger the PL-laser energy difference is, the higher the output characteristics such as the output saturation starting point and the slope efficiency are.

[0123] In addition, in the semiconductor light emitting element 1 of 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 by more than 0.103 eV. Thus, the slope efficiency at the starting point of output saturation can be further improved. Specifically, the slope efficiency can be made to be more than 0.75 W / A. In addition, the peak photon energy of the PL of the active layer 40 may be higher than the peak photon energy of the laser by more than 0.111 V. Thus, the light output and slope efficiency at the starting point of output saturation can be further improved. Specifically, the light output at the starting point of output saturation can be made to be more than 1.4 W, and the slope efficiency can be made to be more than 1.1 W / A. As a result, the semiconductor light emitting element 1 can achieve further high output. In these cases, the current density at the starting point of output saturation can also be 78 kA / mm 2 above.

[0124] In the semiconductor light emitting device 1 of 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 may be 0.250 eV or less. This ensures that gain can be obtained in the active layer 40 of the semiconductor light emitting device 1 .

[0125] In addition, in the semiconductor light emitting element 1 of the present embodiment, it is also possible to Fig.11As shown, in the PL spectrum of the active layer 40, the intensity of the PL at the peak photon energy of the laser is less than 40% of the peak intensity of the PL spectrum. As a result, the absorption of the laser in the active layer 40 can be reduced, so the light output at the start point of output saturation can be increased. In addition, when the PL-laser energy difference is 0.050eV, in the example with the widest half-width in the PL spectrum of the active layer 40 of this embodiment, the intensity of the PL at the peak photon energy of the laser is about 40% of the peak intensity of the PL spectrum.

[0126] Furthermore, in the semiconductor light emitting element 1 of the present embodiment, it is also possible that Fig.11 As shown, in the PL spectrum of the active layer 40, the PL intensity at the peak photon energy of the laser is less than 8% of the peak intensity of the PL spectrum. This can further reduce the absorption of the laser in the active layer 40, so that the light output at the output saturation start point can be further improved.

[0127] In addition, in the semiconductor light emitting element 1 of the present embodiment, when the peak photon energy of the laser is 3.1 eV or more as in the examples, the effect of the semiconductor light emitting element 1 of the present embodiment is more significant. That is, when the peak photon energy is large, the energy of each photon is large, so the influence of heat generation due to light absorption is large. In particular, when the peak photon energy of the laser is 3.1 eV or more, the effect of reducing light absorption of the semiconductor light emitting element 1 of the present embodiment becomes significant. Therefore, it is also possible to suppress light damage to the semiconductor light emitting element 1 accompanied by light absorption.

[0128] Next, use Figure 17 to Figure 22 The relationship between the spontaneous emission light and the PL spectrum of the semiconductor light emitting element 1 according to the present embodiment will be described. Fig.17 , Fig.18 , Fig.19 and Fig. 20 The graphs show the spontaneous emission spectra and PL spectra of the semiconductor light emitting elements of the comparative example, example 1, example 2, and example 5, respectively. Figures 17 to 20 In the figure, the spontaneous emission spectrum is represented by a solid line, and the PL spectrum is represented by a dotted line. Fig.21 It is a graph showing the relationship between the light output and the PL-spontaneous emission light energy difference at the output saturation starting point of the semiconductor light emitting element 1 of each example and the semiconductor light emitting element of the comparative example. Fig. 22 This is a graph showing the relationship between the slope efficiency and the PL-spontaneous emission light energy difference when the light output of the semiconductor light emitting element 1 of each example and the semiconductor light emitting element of the comparative example is 0.5 W or more and 1.0 W or less. Fig.21 and Fig. 22In the figure, black circles represent data of examples, and black squares represent data of comparative examples.

[0129] like Fig.17 , Fig.21 and Fig. 22 As shown, in the semiconductor light emitting element of the comparative example, the PL-spontaneous emission light energy difference is less than 0.070 eV. Figures 18 to 20 As shown, in the semiconductor light emitting elements 1 of Examples 1, 2, and 5, the PL-spontaneous emission light energy difference is 0.070 eV or more. More specifically, in the semiconductor light emitting elements 1 of each Example, the peak photon energy of the PL of the active layer 40 is 0.070 eV or more higher than the peak photon energy of the spontaneous emission light. As for the semiconductor light emitting elements 1 of Examples 3 and 4, Fig.11 As shown, it has the same characteristics as the semiconductor light emitting element 1 of Example 2.

[0130] It is known that the peak photon energy of the laser of the semiconductor light emitting element changes according to the conditions of the resonator, and in the gain region of the spontaneous emission light (the photon energy range in which gain is obtained), the peak photon energy of the spontaneous emission light may increase or decrease. In the semiconductor light emitting element 1 of each embodiment, the peak photon energy of the PL of the active layer 40 is higher than the peak photon energy of the spontaneous emission light by more than 0.070 eV. Therefore, in the semiconductor light emitting element 1 of the present embodiment, even if the oscillation wavelength deviates from the target wavelength depending on the conditions of the resonator, the difference in the peak photon energy between the PL and the laser can be ensured to be sufficiently large, so that the absorption of the laser in the active layer 40 can be reduced. Therefore, the light output at the start point of output saturation can be improved.

[0131] In addition, in the semiconductor light emitting element 1 of 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 spontaneous emission light by 0.090 eV or more. Thus, the light output and slope efficiency at the output saturation starting point can be further improved. As a result, the semiconductor light emitting element 1 can achieve further high output.

[0132] In the semiconductor light emitting element 1 of the present embodiment, the difference between the peak photon energy of PL and the peak photon energy of spontaneous emission light in the active layer 40 may be 0.250 eV or less. This ensures that gain can be obtained in the active layer 40 of the semiconductor light emitting element 1 .

[0133] Here, the structure of the semiconductor light emitting element 1 for obtaining the above-mentioned characteristics is described. Figure 6As shown, the difference in band gap energy between the barrier layers 41, 43 and the well layer 42 is less than 0.140 eV. Although the detailed mechanism is unknown, when the difference in band gap energy between each barrier layer and the well layer 42 is small as in the semiconductor light emitting element 1 of the present embodiment, a part of the carriers injected into the well layer 42 passes through each barrier layer and flows out to the first light guide layer 61 or the second light guide layer 62. It is speculated that the PL spectrum of the active layer 40 is shifted to the high energy side by the carriers flowing out to each light guide layer.

[0134] In addition, in this embodiment, if Figure 6 As shown, 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. In addition, the difference in band gap energy between the second light guide layer 62 and the barrier layer 43 closest to the second light guide layer 62 is less than 0.080 eV. In this way, by reducing the band gap energy between each light guide layer and the barrier layer closest to the light guide layer, carriers that have passed through the barrier and flowed out into the light guide layer can be returned to the well layer 42 again.

[0135] In addition, like the semiconductor light emitting element 1 of Examples 2 to 4, the semiconductor light emitting element 1 of this embodiment may also include an electron blocking layer disposed above the barrier layer 43 closest to the second cladding layer 50 and in contact with the barrier layer 43. The electrons injected into the well layer 42 of the semiconductor light emitting element 1 are easy to cross the barrier layer 43 because their effective mass is smaller than that of holes. Therefore, the number of carriers crossing the barrier layer 43 closer to the second cladding layer 50 as a P-type cladding is greater than the number of holes crossing the barrier layer 41 closer to the first cladding layer 30. Therefore, in the semiconductor light emitting element 1 of Examples 2 to 4, an electron blocking layer 70 disposed above the barrier layer 43 and in contact with the barrier layer 43 is included. As a result, a region having a band gap energy lower than that of the barrier layer 43 and the electron blocking layer 70 is not formed between the barrier layer 43 and the electron blocking layer 70. Therefore, the electrons that have crossed the barrier layer 43 easily return to the well layer 42. This can reduce the probability of recombination between electrons and holes in regions other than the well layer 42 , thereby improving the light emission efficiency (and slope efficiency, etc.) of the semiconductor light emitting element 1 .

[0136] In addition, when the barrier layer 43 and the second light guide layer 62 of the semiconductor light emitting element 1 of Examples 1 and 5 have the same composition, the adjacent barrier layer 43 and the second light guide layer 62 can also be regarded as one barrier layer. In this case, in the semiconductor light emitting element 1 of Examples 1 and 5, the electron blocking layer can be regarded as being in contact with the barrier layer obtained by merging the barrier layer 43 and the second light guide layer 62. Therefore, the semiconductor light emitting element 1 of Examples 1 and 5 can also obtain the same effect brought by the electron blocking layer 70 as the semiconductor light emitting element 1 of Examples 2 to 4.

[0137] In addition, it is also possible that the semiconductor light-emitting element 1 of the present embodiment has at least one of a first light guide layer 61 disposed between the first cladding layer 30 and the active layer 40 and a second light guide layer 62 disposed between the active layer 40 and the second cladding layer 50, and the thickness of the well layer 42 is 17.5 nm or more.

[0138] Due to the combined effect of the relatively thick well layer 42 and the presence of carriers in each light guide layer, the PL spectrum can be made 0.050 eV greater than the peak photon energy of the laser. In addition, in each of the embodiments, the active layer 40 has a single well layer 42, but it may also have a plurality of well layers. That is, the active layer 40 may also have a multiple quantum well structure. In this case, the total thickness of the plurality of well layers may be 17.5 nm.

[0139] In addition, it is also possible that, as in the semiconductor light-emitting element 1 of Embodiment 5, each barrier layer is composed of Al z Ga 1－z N (0 < z < 1), and the well layer 42 is composed of Al x In y Ga 1－x－y N (0 < x < 1, 0 < y < 1). Thus, the same PL-laser energy difference and PL-spontaneous emission light energy difference as in the case where the well layer 42 is composed of InGaN as in the semiconductor light-emitting elements 1 of Embodiments 1 to 4 can be obtained. Furthermore, in the semiconductor light-emitting element 1 of Embodiment 5, the light output and slope efficiency at the output saturation start point can be improved compared with the semiconductor light-emitting elements 1 of Embodiments 1 to 4.

[0140] In addition, in the case where the active layer 40 has a multiple quantum well structure, it is also possible that three or more barrier layers are composed of AlzGa1−zN (0 < z < 1), and two or more well layers are composed of AlxInyGa1−x−yN (0 < x < 1, 0 < y < 1). In this case, the same effects as in the case of the single quantum well structure (for example, Embodiment 5) can also be obtained.

[0141] (Modification examples, etc.)

[0142] As described above, the semiconductor light-emitting element of the present disclosure has been described based on each of the embodiments of the embodiment, but the present disclosure is not limited to each of the embodiments of the above-described embodiment.

[0143] For example, in the above-mentioned embodiments, the semiconductor light emitting element 1 is an example of a semiconductor laser element, but the semiconductor light emitting element 1 is not limited to a semiconductor laser element. For example, the semiconductor light emitting element of the present disclosure may include an active layer 40, and the peak photon energy of the PL of the active layer 40 is 0.070 eV or more higher than the peak photon energy of the spontaneous emission light emitted from the semiconductor light emitting element to which current is injected. The semiconductor light emitting element of the present disclosure may also be a superluminescent diode, for example.

[0144] The semiconductor light emitting element 1 of each of the above-mentioned embodiments includes one layer of the second light guiding layer 62 between the active layer 40 and the second cladding layer 50, but may also include two or more layers of the second light guiding layer 62. For example, the semiconductor light emitting element of the present disclosure may also include the second light guiding layer 62 disposed between the active layer 40 and the electron blocking layer 70, and the second light guiding layer 62 disposed between the electron blocking layer 70 and the second cladding layer 50. In this case, the structures of the second light guiding layers 62 may also be different from each other.

[0145] The active layer 40 of the semiconductor light emitting element 1 in each of the above-mentioned embodiments has a single quantum well structure, but may have a multiple quantum well structure, that is, a structure in which three or more barrier layers and two or more well layers are alternately stacked.

[0146] In the above embodiment, the well layer 42 is composed of InGaN or AlInGaN, but the structure of the well layer 42 is not limited thereto. The well layer 42 may be composed of GaN, for example.

[0147] In addition, the present disclosure also includes forms obtained by implementing various modifications that can be conceived by those skilled in the art to the above-mentioned embodiments and modifications, and forms achieved by arbitrarily combining the constituent elements and functions of the above-mentioned embodiments and modifications without departing from the gist of the present disclosure.

[0148] Industrial Applicability

[0149] The semiconductor light emitting element or the like disclosed in the present invention can be used as a light source for laser processing or the like as a high-output and high-efficiency light source, for example.

[0150] Description of Reference Numerals

[0151] 1Semiconductor light emitting element

[0152] 1F, 1R end face

[0153] 10 substrate

[0154] 21 Basal layer

[0155] 22 Anti-crack layer

[0156] 30 First cladding

[0157] 40 Active layer

[0158] 41, 43 Barrier layer

[0159] 42-well layer

[0160] 50 Second cladding

[0161] 50R Ridge

[0162] 50T slot

[0163] 60 light guide layer

[0164] 61 First light guide layer

[0165] 62 Second light guide layer

[0166] 70Electron blocking layer

[0167] 80 insulation layer

[0168] 91 Upper electrode

[0169] 92 Lower electrode

Claims

1. A semiconductor light emitting element, characterized in that: have: substrate; A first cladding layer of a first conductivity type is disposed above the substrate; An active layer, disposed above the first cladding layer; A second cladding layer of a second conductivity type different from the first conductivity type is disposed above the active layer; as well as A light guide layer, disposed between the first cladding layer and the second cladding layer; The peak photon energy of the photoluminescence of the active layer is higher by 0.050 eV or more than the peak photon energy of the laser light emitted from the semiconductor light emitting element to which current is injected.

2. A semiconductor light emitting element, characterized in that: have: substrate; A first cladding layer of a first conductivity type is disposed above the substrate; An active layer, disposed above the first cladding layer; A second cladding layer of a second conductivity type different from the first conductivity type is disposed above the active layer; as well as A light guide layer, disposed between the first cladding layer and the second cladding layer; In a spectrum of photoluminescence of the active layer, an intensity of the photoluminescence at a peak photon energy of laser light emitted from the semiconductor light emitting element to which current is injected is 40% or less of a peak intensity of the spectrum.

3. A semiconductor light emitting element comprising an active layer, characterized in that: The peak photon energy of the photoluminescence of the active layer is higher by 0.070 eV or more than the peak photon energy of the spontaneous emission light emitted from the semiconductor light emitting element to which current is injected.

4. The semiconductor light emitting element according to claim 3, wherein: Also available: substrate; A first cladding layer of a first conductivity type, disposed between the substrate and the active layer; A second cladding layer of a second conductivity type different from the first conductivity type is disposed above the active layer; as well as The light guiding layer is arranged between the first cladding layer and the second cladding layer.

5. The semiconductor light emitting element according to any one of claims 1, 2 and 4, characterized in that: The peak photon energy of the laser light emitted from the semiconductor light emitting element is 3.1 eV or more.

6. The semiconductor light emitting element according to any one of claims 1, 2, 4 and 5, characterized in that: The light output of the semiconductor light emitting element is 0.7 W or more at the output saturation starting point.

7. The semiconductor light emitting element according to any one of claims 1, 2, 4 and 5, characterized in that: The current density at the output saturation starting point of the semiconductor light emitting element is 60 kA / mm 2 above.

8. The semiconductor light emitting element according to any one of claims 1, 2, 4 to 7, characterized in that The active layer has a quantum well structure in which two or more barrier layers and one or more well layers are alternately stacked; A 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.

9. The semiconductor light emitting element according to any one of claims 1, 2, 4 to 7, characterized in that: 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 at least one of a first light guide layer disposed between the first cladding layer and the active layer and a second light guide layer disposed between the active layer and the second cladding layer; The first optical guide layer and the second optical guide layer each have a smaller band gap energy than the two or more barrier layers, and a larger band gap energy than the one or more well layers; The difference in band gap energy between the first light guiding layer and the barrier layer closest to the first light guiding layer among the two or more barrier layers is less than 0.080 eV; A difference in band gap energy between the second light guiding layer and a barrier layer closest to the second light guiding layer among the two or more barrier layers is less than 0.080 eV.

10. The semiconductor light emitting element according to claim 9, wherein: further comprising an electron blocking layer disposed above and in contact with a barrier layer closest to the second cladding layer among the two or more barrier layers; The light guide layer includes the first light guide layer.

11. The semiconductor light emitting element according to any one of claims 1, 2, 4 to 7, wherein: 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 at least one of a first light guide layer disposed between the first cladding layer and the active layer and a second light guide layer disposed between the active layer and the second cladding layer; The total thickness of the one or more well layers is 17.5 nm or more.

12. The semiconductor light emitting element according to any one of claims 1, 2, 4 to 7, characterized in that: 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 above two barrier layers are made of Al z Ga 1－z N constitutes, 0 <z<1; The above-mentioned one or more well layers are made of Al x In y Ga 1－x－y N constitutes, 0 <x<1,0<y<1。 13. A semiconductor light emitting element, characterized in that: have: substrate; A first cladding layer of a first conductivity type is disposed above the substrate; An active layer, disposed above the first cladding layer; A second cladding layer of a second conductivity type different from the first conductivity type is disposed above the active layer; as well as 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 at least one of a first light guide layer disposed between the first cladding layer and the active layer and a second light guide layer disposed between the active layer and the second cladding layer; The first optical guide layer and the second optical guide layer each have a smaller band gap energy than the two or more barrier layers, and a larger band gap energy than the one or more well layers; The difference in band gap energy between the first light guiding layer and the barrier layer closest to the first light guiding layer among the two or more barrier layers is less than 0.080 eV; A difference in band gap energy between the second light guiding layer and a barrier layer closest to the second light guiding layer among the two or more barrier layers is less than 0.080 eV.

14. The semiconductor light emitting element according to claim 13, wherein: further comprising an electron blocking layer disposed above and in contact with a barrier layer closest to the second cladding layer among the two or more barrier layers; The light guide layer includes the first light guide layer.

15. The semiconductor light emitting element according to claim 13 or 14, characterized in that: The total thickness of the one or more well layers is 17.5 nm or more.

16. The semiconductor light emitting element according to any one of claims 13 to 15, wherein: The above two barrier layers are made of Al z Ga 1－z N constitutes, 0 <z<1; The above-mentioned one or more well layers are made of Al x In y Ga 1－x－y N constitutes, 0 <x<1,0<y<1。 17. The semiconductor light emitting element according to any one of claims 13 to 16, wherein: The peak photon energy of the laser light emitted from the semiconductor light emitting element is 3.1 eV or more.

18. The semiconductor light emitting element according to any one of claims 13 to 17, wherein The light output of the semiconductor light emitting element is 0.7 W or more at the output saturation starting point.

19. The semiconductor light emitting element according to any one of claims 13 to 18, wherein The current density at the output saturation starting point of the semiconductor light emitting element is 60 kA / mm 2 above.

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