Nitride semiconductor light-emitting element

Abstract

A nitride semiconductor light-emitting element (100) that emits light and is provided with an N-type cladding layer (104), an N-side light guide layer (106), an active layer (107), an electron blocking layer (109), a P-type intermediate layer (110), a P-side light guide layer (111), and a P-type cladding layer (112), the average band gap energy of the electron blocking layer (109) being greater than the average band gap energy of the P-type cladding layer (112), and the average band gap energy of the P-type intermediate layer (110) being greater than the average band gap energy of the P-type cladding layer (112). The average band gap energy of the P-type intermediate layer (110) is larger than the average band gap energy of the P-side light guide layer (111) and smaller than the average band gap energy of the electron blocking layer (109), the average impurity concentration of the P-type intermediate layer (110) is lower than the average impurity concentration of the electron blocking layer (109) and higher than the average impurity concentration of the P-side light guide layer (111), and the peak wavelength of light is less than 400 nm.

Description

Technical Field

[0001] The present disclosure relates to a nitride-based semiconductor light-emitting device. Background Art

[0002] Conventionally, there are known nitride-based semiconductor light-emitting elements such as nitride-based semiconductor laser elements that emit light in the ultraviolet wavelength range (e.g., Patent Document 1, etc.). Since the energy of light in the ultraviolet range is greater than that of visible light, light absorption increases, especially in the optical guiding layer, etc., which has a relatively small band gap energy. For example, in the nitride-based semiconductor laser element described in Patent Document 1, the band gap energy is increased by increasing the Al composition ratio of each semiconductor layer such as the optical guiding layer and the cladding layer. This is intended to suppress light absorption in each semiconductor layer.

[0003] (Prior art literature)

[0004] (Patent Document)

[0005] Patent Document 1: Japanese Patent Application Laid-Open No. 2010-258363 Summary of the invention

[0006] Problems to be solved by the invention

[0007] However, when the Al composition ratio of each semiconductor layer is increased, the stress inside the semiconductor stack increases due to the lattice mismatch with the GaN substrate of the nitride-based semiconductor laser element. Therefore, the semiconductor stack is prone to damage, cracks, defects, etc. In addition, by increasing the Al composition ratio of each semiconductor layer, the proportion of impurities that play an acceptor or donor function among the impurities doped in each semiconductor layer decreases. Accordingly, since the resistance in each semiconductor layer increases, the operating voltage of the nitride-based semiconductor laser element increases.

[0008] The present disclosure aims to solve the above-mentioned problems and to reduce the Al composition ratio in each semiconductor layer and suppress light loss in a nitride-based semiconductor light-emitting element that emits light in the ultraviolet wavelength range.

[0009] Means for solving problems

[0010] In order to solve the above-mentioned problems, one method of the nitride-based semiconductor light-emitting element involved in the present disclosure is that the nitride-based semiconductor light-emitting element that emits light comprises a substrate; an N-type cladding layer disposed above the substrate and containing Al; an N-side light-guiding layer disposed above the N-type cladding layer and containing Al; an active layer disposed above the N-side light-guiding layer and including one or more well layers and a plurality of barrier layers containing Al; an electron blocking layer disposed above the active layer and containing Al; a P-type intermediate layer disposed above the electron blocking layer and containing Al; and a P-type intermediate layer disposed above the P-type intermediate layer. and a P-side light guiding layer containing Al; and a P-type cladding layer disposed above the P-side light guiding layer and containing Al, wherein in the nitride-based semiconductor light-emitting element, the average band gap energy of the electron blocking layer is greater than the average band gap energy of the P-type cladding layer, the average band gap energy of the P-type intermediate layer is greater than the average band gap energy of the P-side light guiding layer and is smaller than the average band gap energy of the electron blocking layer, the average impurity concentration of the P-type intermediate layer is lower than the average impurity concentration of the electron blocking layer and is higher than the average impurity concentration of the P-side light guiding layer, and the peak wavelength of the light is less than 400nm.

[0011] In order to solve the above-mentioned problems, another embodiment of the nitride-based semiconductor light-emitting element involved in the present disclosure is that the nitride-based semiconductor light-emitting element that emits light comprises: a substrate; an N-type cladding layer arranged above the substrate and containing Al; an N-type intermediate layer arranged above the N-type cladding layer and containing Al; an N-side light-guiding layer arranged above the N-type intermediate layer and containing Al; an active layer arranged above the N-side light-guiding layer and including one or more well layers and multiple barrier layers containing Al; a P-side light-guiding layer arranged above the active layer and containing Al; and a P-type cladding layer arranged above the P-side light-guiding layer and containing Al, in which the average band gap energy of the N-type intermediate layer is larger than the average band gap energy of the N-side light-guiding layer and smaller than the average band gap energy of the N-type cladding layer, the average impurity concentration of the N-type intermediate layer is lower than the average impurity concentration of the N-type cladding layer and higher than the average impurity concentration of the N-side light-guiding layer, and the peak wavelength of the light is less than 400nm.

[0012] Effects of the Invention

[0013] According to the present disclosure, in a nitride-based semiconductor light-emitting element that emits light in an ultraviolet wavelength range, it is possible to suppress light loss while reducing the Al composition ratio in each semiconductor layer. BRIEF DESCRIPTION OF THE DRAWINGS

[0014] Figure 1 This is a schematic plan view showing the overall structure of the nitride-based semiconductor light-emitting element according to Embodiment 1.

[0015] Figure 2 This is a schematic cross-sectional view showing the overall structure of the nitride-based semiconductor light-emitting element according to Embodiment 1.

[0016] Figure 3 This is a schematic line graph showing the distribution of the band gap energy and the impurity concentration of the nitride-based semiconductor light-emitting element according to Comparative Example 1 in the stacking direction.

[0017] Figure 4 This is a schematic line graph showing the distribution of the band gap energy and the impurity concentration in the stacking direction of the nitride-based semiconductor light-emitting element according to Embodiment 1.

[0018] Figure 5 is a line graph showing the attenuation coefficient spectrum in the AlGaN layer.

[0019] Figure 6 This is a schematic cross-sectional view showing the shape of the side surface of the ridge portion according to the first embodiment.

[0020] Figure 7 It is a line graph showing the relationship between the order of the transverse mode of the laser beam and the waveguide loss in the nitride-based semiconductor light-emitting element.

[0021] Figure 8 This is a schematic line graph showing the distribution of the band gap energy and impurity concentration in the stacking direction of the nitride-based semiconductor light-emitting element involved in Embodiment 2.

[0022] Fig. 9 This is a schematic cross-sectional view showing the overall structure of the nitride-based semiconductor light-emitting element according to Embodiment 3.

[0023] Fig.10 This is a schematic line graph showing the distribution of the band gap energy and impurity concentration in the stacking direction of the nitride-based semiconductor light-emitting element involved in Embodiment 4.

[0024] Fig.11 This is a schematic line graph showing the distribution of the band gap energy and impurity concentration in the stacking direction of the nitride-based semiconductor light-emitting element involved in Embodiment 5.

[0025] Fig.12 This is a schematic line graph showing the distribution of the band gap energy and impurity concentration in the stacking direction of the nitride-based semiconductor light-emitting element involved in Embodiment 6.

[0026] Fig.13 This is a schematic cross-sectional view showing the overall structure of a nitride-based semiconductor light-emitting element according to Embodiment 7.

[0027] Fig.14 This is a schematic line graph showing the distribution of the band gap energy and impurity concentration in the stacking direction of the nitride-based semiconductor light-emitting element involved in Embodiment 7.

[0028] Fig.15 This is a schematic line graph showing the distribution of the band gap energy and impurity concentration in the stacking direction of the nitride-based semiconductor light-emitting element involved in Embodiment 8.

[0029] Fig.16 This is a schematic line graph showing the distribution of the band gap energy and impurity concentration in the stacking direction of the nitride-based semiconductor light-emitting element involved in Embodiment 9.

[0030] Fig.17 This is a schematic line graph showing the distribution of the band gap energy and impurity concentration in the stacking direction of the nitride-based semiconductor light-emitting element involved in Embodiment 10.

[0031] Fig.18 This is a schematic cross-sectional view showing the overall structure of the nitride-based semiconductor light-emitting element involved in Embodiment 11.

[0032] Fig.19 This is a schematic line graph showing the distribution of the band gap energy and impurity concentration in the stacking direction of the nitride-based semiconductor light-emitting element involved in Embodiment 11.

[0033] Fig. 20 It is a line graph showing the relationship between the waveguide loss of Configuration Example 1 of the nitride-based semiconductor light-emitting element involved in Embodiment 11 and the Al composition ratio of the lower P-side light guiding layer.

[0034] Fig.21 It is a line graph showing the relationship between the operating current and the Al composition ratio of the lower P-side light guiding layer when the power consumption is 0.5 W in the configuration example 1 of the nitride-based semiconductor light-emitting element involved in the eleventh embodiment.

[0035] Fig. 22 It is a line graph showing the relationship between the operating voltage value when the power consumption is 0.5 W and the Al composition ratio of the lower P-side light guiding layer in the configuration example 1 of the nitride-based semiconductor light-emitting element involved in the eleventh embodiment.

[0036] Fig.23 It is a line graph showing the relationship between the optical confinement factor of Configuration Example 1 of the nitride-based semiconductor light-emitting element involved in Embodiment 11 and the Al composition ratio of the lower P-side light guiding layer.

[0037] Fig.24It is a line graph showing the relationship between the effective refractive index difference ΔN of Configuration Example 1 of the nitride-based semiconductor light-emitting element involved in Embodiment 11 and the Al composition ratio of the lower P-side light guiding layer.

[0038] Fig.25 It is a line graph showing the relationship between WPE and the Al composition ratio of the lower P-side light guiding layer when the power consumption is 0.5 W in Configuration Example 1 of the nitride-based semiconductor light-emitting element involved in Embodiment 11.

[0039] Fig.26 It is a diagram showing the structure and characteristics of Examples 1 to 4 of the nitride-based semiconductor light-emitting element involved in Embodiment 11.

[0040] Fig. 27 It is a line graph showing the relationship between the waveguide loss of Configuration Example 2 of the nitride-based semiconductor light-emitting element involved in Embodiment 11 and the In composition ratio of the lower P-side optical guiding layer.

[0041] Fig.28 It is a line graph showing the relationship between the operating current and the In composition ratio of the lower P-side light guiding layer when the power consumption is 0.5 W in the configuration example 2 of the nitride-based semiconductor light-emitting element involved in the embodiment 11.

[0042] Fig.29 It is a line graph showing the relationship between the operating voltage value when the power consumption is 0.5 W and the In composition ratio of the lower P-side light guiding layer in the configuration example 2 of the nitride-based semiconductor light-emitting element involved in the embodiment 11.

[0043] Fig.30 It is a line graph showing the relationship between the optical confinement factor of Configuration Example 2 of the nitride-based semiconductor light-emitting element involved in Embodiment 11 and the In composition ratio of the lower P-side light-guiding layer.

[0044] Fig.31 It is a line graph showing the relationship between the effective refractive index difference ΔN and the In composition ratio of the lower P-side light guiding layer in Configuration Example 2 of the nitride-based semiconductor light-emitting element involved in Embodiment 11.

[0045] Fig.32 It is a line graph showing the relationship between WPE and the In composition ratio of the lower P-side light guiding layer when the power consumption is 0.5 W in Configuration Example 2 of the nitride-based semiconductor light-emitting element involved in Embodiment 11.

[0046] Fig.33 It is a diagram showing the structure and characteristics of Examples 5 to 8 of the nitride-based semiconductor light-emitting element involved in Embodiment 11. DETAILED DESCRIPTION

[0047] The embodiments of the present disclosure are described below with reference to the accompanying drawings. In addition, the embodiments to be described below are all specific examples of the present disclosure. Therefore, the values, shapes, materials, components, and the configuration positions or connection methods of the components shown in the following embodiments are all examples, and their purpose is not to limit the present disclosure.

[0048] Furthermore, each figure is a schematic diagram, not a strict illustration. Therefore, the scales, etc. in each figure are not necessarily the same. In addition, in each figure, substantially the same structure is given the same symbol, and there are cases where repeated descriptions are omitted or simplified.

[0049] Furthermore, in this specification, expressions indicating the relationship between equivalent elements, expressions indicating the shapes of elements such as flat, parallel, vertical, plate-shaped, curved, etc., and numerical ranges do not express strict meanings but include substantially equivalent ranges, for example, differences of a few percent.

[0050] Furthermore, the expressions "above" and "below" in this specification do not refer to the vertically above and vertically below in absolute space, but are defined by relative positional relationships based on the stacking order in the stacking structure. Furthermore, the expressions "above" and "below" are applicable not only to the case where two components are arranged with a gap between them and there are other components between them, but also to the case where two components are arranged in a state of contact with each other.

[0051] (Implementation Method 1)

[0052] The nitride-based semiconductor light-emitting element according to Embodiment 1 will be described.

[0053] [1-1. Overall composition]

[0054] First, use Figure 1 , Figure 2 The overall structure of the nitride-based semiconductor light-emitting element according to this embodiment will be described. Figure 1 as well as Figure 2 Each of them is a schematic plan view and a cross-sectional view showing the overall structure of the nitride-based semiconductor light-emitting element 100 according to the present embodiment. Figure 2 Shows Figure 1 The cross section at the II-II line of FIG. In addition, each figure shows the X-axis, Y-axis, and Z-axis that are orthogonal to each other. The X-axis, Y-axis, and Z-axis are a right-handed orthogonal coordinate system. The stacking direction of the nitride-based semiconductor light-emitting element 100 is parallel to the Z-axis direction, and the main emission direction of the light (laser beam) is parallel to the Y-axis direction.

[0055] The nitride-based semiconductor light emitting device 100 is Figure 2 As shown, a semiconductor stack 100S including a nitride-based semiconductor layer is provided, and light is emitted from an end face 100F (see FIG. 1 ) in a direction perpendicular to the stacking direction (i.e., the Z-axis direction) of the semiconductor stack 100S. Figure 1 ) is emitted. In the present embodiment, the nitride-based semiconductor light-emitting element 100 is a semiconductor laser element having two end faces 100F and 100R forming a resonator. End face 100F is a front face that emits a laser beam, and end face 100R is a rear face having a higher reflectivity than end face 100F. Furthermore, the nitride-based semiconductor light-emitting element 100 has a waveguide formed between end face 100F and end face 100R. Although there is no particular limitation on the reflectivity of end faces 100F and 100R, in the present embodiment, they are 16% and 95%, respectively. The resonator length (i.e., the distance between end face 100F and end face 100R) of the nitride-based semiconductor light-emitting element 100 involved in the present embodiment is about 800μm. The peak wavelength of the light emitted by the nitride-based semiconductor light-emitting element 100 is less than 400nm. For example, the nitride-based semiconductor light-emitting element 100 emits ultraviolet light having a peak wavelength in the 375nm band. In addition, the nitride-based semiconductor light-emitting element 100 can also emit ultraviolet light having a peak wavelength in a wavelength band other than 375 nm.

[0056] like Figure 2 As shown, the nitride-based semiconductor light-emitting element 100 includes a substrate 101, a semiconductor stack 100S, a current blocking layer 120, a P-side electrode 131, a close contact layer 132, a pad electrode 133, and an N-side electrode 140. The semiconductor stack 100S includes a base layer 102, a buffer layer 103, an N-type cladding layer 104, an N-side optical guiding layer 106, an active layer 107, an electron blocking layer 109, a P-type intermediate layer 110, a P-side optical guiding layer 111, a P-type cladding layer 112, and a contact layer 113. An element separation groove 10T is formed on the side surface (end surface in the X-axis direction) of the semiconductor stack 100S. The element separation groove 10T is a groove for singulating the nitride-based semiconductor light-emitting element 100.

[0057] The substrate 101 is a plate-shaped member formed of a nitride-based semiconductor that serves as a base for the nitride-based semiconductor light-emitting element 100. The substrate 101 has primary surfaces 101a and 101b. In this embodiment, the substrate 101 is disposed below the N-type cladding layer 104 and is composed of N-type GaN. More specifically, the substrate 101 is doped with an average concentration of 1.4×10 18 cm -3 The thickness of SiGaN substrate is 85μm.

[0058] The base layer 102 is an N-type nitride semiconductor layer disposed on the substrate 101. The average Al composition ratio of the base layer 102 may be smaller than that of the N-type cladding layer 104. In the present embodiment, the base layer 102 is a layer doped with an average concentration of 1.0×10 18 cm -3 The Si film thickness is 1000nm N-type Al 0.02 Ga 0.98 N layers.

[0059] In the present disclosure, the average concentration of impurities in each layer (i.e., average impurity concentration) refers to the value of the impurity concentration obtained by integrating the magnitude of the impurity concentration at a certain position of the layer in the stacking direction from the position of the interface on the side close to the substrate 101 to the position of the interface on the side far from the substrate 101 in the stacking direction of the layer, and dividing it by the film thickness of the layer (the distance between the interface on the side close to the substrate 101 and the interface on the side far from the substrate 101). Impurities refer to impurities doped in order to obtain N-type conductivity in an N-type semiconductor layer and impurities doped in order to obtain P-type conductivity in a P-type semiconductor layer.

[0060] The average Al composition ratio of a certain layer refers to the value of the Al composition ratio obtained by integrating the Al composition ratio at a certain position of the layer in the stacking direction from the position of the interface on the side closer to the substrate 101 in the stacking direction of the layer to the position of the interface on the side farther from the substrate 101, and dividing it by the film thickness of the layer.

[0061] The buffer layer 103 is an N-type nitride semiconductor layer disposed between the substrate 101 and the N-type cladding layer 104. In the present embodiment, the buffer layer 103 is disposed on the base layer 102. In the present embodiment, the buffer layer 103 has: 18 cm -3 The Si layer is an N-type GaN layer with a thickness of 10 nm, and the average concentration of 1.0×10 18 cm -3 The Si film thickness is 150nm N-type In 0.04 Ga 0.96 The N layer and the layer disposed above the layer are doped with an average concentration of 1.0×10 18 cm -3 The film thickness of Si is 10nm for the N-type GaN layer.

[0062] The N-type cladding layer 104 is an N-type nitride semiconductor layer containing Al disposed on the substrate 101. In the present embodiment, the N-type cladding layer 104 is disposed on the buffer layer 103. The N-type cladding layer 104 has a smaller average refractive index and a larger average band gap energy than the active layer 107. Furthermore, the N-type cladding layer 104 has a smaller average refractive index and a larger average band gap energy than the N-side optical guiding layer 106. The average Al composition ratio of the N-type cladding layer 104 is greater than the average Al composition ratio of the N-side optical guiding layer 106. The average Al composition ratio of the N-type cladding layer 104 can be less than 10%. In the present embodiment, the N-type cladding layer 104 is doped with an average concentration of 1.0×10 18 cm -3 The Si film thickness is 900nm N-type Al 0.065 Ga 0.935 N layers.

[0063] Here, in the present disclosure, the average band gap energy of a certain layer refers to the value of the band gap energy obtained by integrating the size of the band gap energy at a certain position of the layer in the stacking direction from the position of the interface on the side close to the substrate 101 in the stacking direction of the layer to the position of the interface on the side far from the substrate 101, and dividing it by the film thickness of the layer.

[0064] Furthermore, the average refractive index of a certain layer refers to the refractive index value obtained by integrating the magnitude of the refractive index at a certain position in the stacking direction of the layer in the stacking direction from the position of the interface on the side close to the substrate 101 in the stacking direction of the layer to the position of the interface on the side far from the substrate 101, and dividing it by the film thickness of the layer.

[0065] The N-side light guiding layer 106 is a nitride semiconductor layer that is disposed above the N-type cladding layer 104 and contains Al. The N-side light guiding layer 106 has a larger average refractive index and a smaller average band gap energy than the N-type cladding layer 104. The average Al composition ratio of the N-side light guiding layer 106 can be less than 10%. In this embodiment, the N-side light guiding layer 106 has an average doping concentration of 1.0×10 18 cm -3 The Si film thickness is 127nm N-type Al 0.03 Ga 0.97 N layer, and an undoped Al layer with a thickness of 80 nm disposed above the layer 0.03 Ga 0.97 In the present disclosure, an undoped layer refers to a layer having an impurity concentration less than 1.0×10 18 cm -3 semiconductor layer.

[0066] The active layer 107 is a nitride-based semiconductor layer that is disposed above the N-side light-guiding layer 106 and includes a well layer 107b, and barrier layers 107a and 107c containing Al. The well layer 107b is disposed between the barrier layer 107a and the barrier layer 107c. In this embodiment, the active layer 107 emits ultraviolet light. In addition, the structure of the active layer 107 is not limited thereto. For example, the active layer 107 may have a multi-quantum well structure. Specifically, the active layer 107 may have more than three barrier layers and more than two well layers. That is, the active layer 107 includes more than one well layer and a plurality of barrier layers.

[0067] The barrier layers 107a and 107c are nitride-based semiconductor layers that are disposed above the N-side optical guiding layer 106 and function as barriers of the quantum well structure. The barrier layer 107c is disposed above the barrier layer 107a. In this embodiment, the average band gap energy of each of the barrier layers 107a and 107c is greater than the average band gap energy of the well layer 107b. In this embodiment, the barrier layer 107a is an undoped Al film with a thickness of 14 nm. 0.04 Ga 0.96 The barrier layer 107c is an undoped Al layer with a thickness of 12 nm. 0.04 Ga 0.96 N layers.

[0068] The well layer 107b is a nitride-based semiconductor layer that is disposed above the barrier layer 107a and functions as a well of a quantum well structure. In this embodiment, the well layer 107b is an undoped In layer with a film thickness of 17.5 nm. 0.01 Ga 0.99 N layers.

[0069] The electron blocking layer 109 is a P-type nitride semiconductor layer containing Al and arranged above the active layer 107. The average band gap energy of the electron blocking layer 109 is larger than the average band gap energy of the barrier layer 107c. Thus, the leakage of electrons from the active layer 107 to the P-type cladding layer 112 can be suppressed. In the present embodiment, the average band gap energy of the electron blocking layer 109 is larger than the average band gap energy of each of the P-type intermediate layer 110 and the P-type cladding layer 112. The average impurity concentration of the electron blocking layer 109 is higher than the average impurity concentration of each of the P-type intermediate layer 110 and the P-side optical guiding layer 111. In the present embodiment, the electron blocking layer 109 is doped with an average concentration of 1.5×10 19 cm -3 The film thickness of Mg is 1.6nm P-type Al 0.36 Ga 0.64 N layers.

[0070] The P-type intermediate layer 110 is a P-type nitride semiconductor layer that is disposed above the electron blocking layer 109 and contains Al. The average impurity concentration of the P-type intermediate layer 110 is lower than the average impurity concentration of the electron blocking layer 109, and higher than the average impurity concentration of the P-side light guiding layer 111. The average Al composition ratio of the P-type intermediate layer 110 is less than 10%. In addition, the film thickness of the P-type intermediate layer 110 may be greater than the film thickness of the electron blocking layer 109. In this embodiment, the P-type intermediate layer 110 is doped with an average concentration of 1.0×10 19 cm -3 The film thickness of Mg is 20nm P-type Al 0.065 Ga 0.935 N layers.

[0071] The P-side optical guiding layer 111 is a nitride-based semiconductor layer that is disposed above the electron blocking layer 109 and contains Al. In the present embodiment, the P-side optical guiding layer 111 is disposed above the P-type intermediate layer 110. The P-side optical guiding layer 111 has a larger average refractive index and a smaller average band gap energy than the P-type cladding layer 112. In the present embodiment, the average band gap energy of the P-side optical guiding layer 111 is smaller than the average band gap energy of the P-type intermediate layer 110 and the P-type cladding layer 112. The average Al composition ratio of the P-side optical guiding layer 111 is less than 10%. In the present embodiment, the P-side optical guiding layer 111 is doped with an average concentration of 2.0×10 18 cm -3 The film thickness of Mg is 110nm P-type Al 0.03 Ga 0.97 N layers.

[0072] The P-type cladding layer 112 is a P-type nitride semiconductor layer containing Al arranged above the P-side light guiding layer 111. Compared with the active layer 107, the P-type cladding layer 112 is a layer with a small average refractive index and a high average band gap energy. The average band gap energy of the P-type cladding layer 112 is smaller than the average band gap energy of the electron blocking layer 109. The average Al composition ratio of the P-type cladding layer 112 can be less than 10%. The impurity concentration in the end of the P-type cladding layer 112 on the side close to the active layer 107 is lower than the impurity concentration in the end on the side far from the active layer 107. Accordingly, since the impurity concentration in the high light intensity region of the P-type cladding layer 112 can be reduced, the free carrier loss of light due to impurities can be reduced. In the present embodiment, the P-type cladding layer 112 has: an average concentration of 2.0×10 18 cm -3 The film thickness of Mg is 170nm P-type Al 0.065 Ga 0.935 N layer, and the layer doped with an average concentration of 1.0×10 19 cm -3The film thickness of Mg is 300nm and the P-type Al 0.065 Ga 0.935 N layers.

[0073] The contact layer 113 is a P-type nitride semiconductor layer disposed above the P-type cladding layer 112 and in ohmic contact with the P-side electrode 131. In this embodiment, the contact layer 113 has a doping concentration of 2.0×10 19 cm -3 A P-type GaN layer with a thickness of 50 nm and a P-type GaN layer with an average doping concentration of 2.0×10 20 cm -3 The film thickness of the Mg P-type GaN layer is 10 nm.

[0074] A ridge 11R is formed on the contact layer 113 and the P-type cladding layer 112. In this embodiment, a ridge 11R is formed on the contact layer 113, the P-type cladding layer 112, and the P-side optical guide layer 111. In addition, two grooves 11T are formed on the contact layer 113, the P-type cladding layer 112, and the P-side optical guide layer 111, which are arranged along the ridge 11R and extend in the Y-axis direction. In this embodiment, the ridge width W is about 15 μm. And as Figure 2 As shown in FIG. 1 , the distance between the lower end of the ridge 11R (i.e., the bottom of the groove 11T) and the electron blocking layer 109 is set to dc. In this embodiment, the distance dc is 35 nm. That is, the lower portion with a thickness of 15 nm of the P-type intermediate layer 110 with a film thickness of 20 nm and the P-side optical guiding layer 111 with a film thickness of 110 nm is located between the lower end of the ridge 11R and the electron blocking layer 109, and the upper portion with a film thickness of 95 nm of the P-side optical guiding layer 111 is located on the ridge 11R.

[0075] The current blocking layer 120 is an insulating layer that is arranged above the P-type cladding layer 112 and has light-transmitting properties to the light from the active layer 107. The current blocking layer 120 is arranged in a region of the upper surface of the semiconductor stack 100S except for the upper surface of the ridge 11R. In addition, the current blocking layer 120 may also be arranged in a region of a portion of the upper surface of the ridge 11R. For example, the current blocking layer 120 may also be arranged in an edge region of the upper surface of the ridge 11R. In the present embodiment, the current blocking layer 120 is a SiO2 layer having a film thickness of 300 nm.

[0076] The P-side electrode 131 is a conductive layer disposed above the contact layer 113. In the present embodiment, the P-side electrode 131 is in contact with the contact layer 113. The P-side electrode 131 is, for example, a single-layer film or a multi-layer film formed of at least one of Cr, Ti, Ni, Pd, Pt, Ag, and Au. Furthermore, by using Ag having a low refractive index for light in the wavelength range of 375 nm in at least a portion of the P-side electrode 131, it is possible to reduce the leakage of light transmitted in the waveguide to the P-side electrode 131, thereby reducing the waveguide loss occurring in the P-side electrode 131. The refractive index of Ag in the wavelength range of 325 nm to 1500 nm is less than 0.5, and the refractive index in the wavelength range of 360 nm to 950 nm is less than 0.2. In this case, since the P-side electrode 131 contains Ag, the light loss in the P-side electrode 131 can be reduced in the large wavelength range of 325 nm to 950 nm. In this case, even if the thickness of the P-type cladding layer 112 is less than 400 nm, the conduction of light transmitted in the waveguide to the P-side electrode 131 can be reduced, thereby reducing the series resistance of the nitride-based semiconductor light-emitting element 100 and suppressing the increase of waveguide loss. In this way, the operating voltage and the operating current can be reduced. In this embodiment, the P-side electrode 131 has a Pd layer with a thickness of 40 nm and a Pt layer with a thickness of 100 nm disposed on the Pd layer.

[0077] The thickness of the P-type cladding layer 112 can be greater than the total thickness of the optical guiding layer on the P side (the thickness of the P-side optical guiding layer 111 in this embodiment) and the total thickness of the optical guiding layer on the N side (the thickness of the N-side optical guiding layer 106 in this embodiment). Accordingly, since the thickness of the P-type cladding layer 112 can be made thick enough to confine light below the P-side electrode 131, waveguide loss can be suppressed. Furthermore, in the case where the P-side electrode 131 contains Ag, for example, the thickness of the P-type cladding layer 112 can also be greater than 200 nm and less than 400 nm. Accordingly, it is possible to suppress waveguide loss and reduce the operating voltage and operating current.

[0078] Furthermore, a layer having a large Al composition ratio such as the P-type cladding layer 112 also deforms greatly relative to the substrate 101 composed of N-type GaN. By reducing the film thickness of the P-type cladding layer 112, the total Al content in the P-type cladding layer 112 can be reduced, thereby reducing the deformation of the P-type cladding layer 112 relative to the substrate 101. Therefore, damage to the nitride-based semiconductor light-emitting element 100 caused by the deformation of the P-type cladding layer 112 can be suppressed.

[0079] Here, in order to stably confine the light propagating in the waveguide within the ridge portion 11R, it is necessary to form an effective refractive index difference (ΔN) such that the effective refractive index of the inner region of the ridge portion 11R is greater than the effective refractive index of the outer region as described later (see Figure 2 ). Specifically, it is necessary to form SiO2 having a lower refractive index than the P-type cladding layer 112 on the sidewall of the ridge 11R to reduce the effective refractive index of the outer region of the ridge 11R. In this case, if the film thickness of the P-type cladding layer 112 is too thin, the area where SiO2 is formed in the thickness direction of the sidewall of the ridge 11R becomes smaller, resulting in a smaller effect of reducing the effective refractive index of the outer region of the ridge 11R. Therefore, the film thickness of the P-type cladding layer 112 needs to be greater than 0.15μm.

[0080] The adhesion layer 132 is a metal layer disposed between the current blocking layer 120 and the pad electrode 133. The adhesion layer 132 has a function of improving the adhesion of the pad electrode 133. In addition, the adhesion layer 132 can be disposed on the P-side electrode 131. In this embodiment, the adhesion layer 132 includes a Ti layer with a thickness of 10 nm disposed on the current blocking layer 120 and a Pt layer with a thickness of 100 nm disposed on the Ti layer.

[0081] The pad electrode 133 is a pad-shaped electrode disposed above the P-side electrode 131. In the present embodiment, the pad electrode 133 is disposed above the P-side electrode 131 and the adhesion layer 132. In the present embodiment, the pad electrode 133 is an Au layer having a film thickness of 2.0 μm.

[0082] The N-side electrode 140 is a conductive layer disposed below the substrate 101 (i.e., the main surface 101b on the opposite side of the main surface 101a of the substrate 101 on which the N-type cladding layer 104 and the like are disposed). The N-side electrode 140 is, for example, a single-layer film or a multi-layer film formed of at least one of Cr, Ti, Ni, Pd, Pt, and Au. In this embodiment, the N-side electrode 140 includes a Ti layer with a thickness of 10 nm, a Pt layer with a thickness of 50 nm, and an Au film with a thickness of 300 nm, which are sequentially stacked from the substrate 101 side.

[0083] [1-2. Effect]

[0084] The effects of the nitride-based semiconductor light-emitting device 100 according to the present embodiment are compared with those of the nitride-based semiconductor light-emitting device according to Comparative Example 1. Figures 3 to 5 Provide explanation. Figure 3 as well as Figure 4 Schematic line graphs showing the distribution of the band gap energy and impurity concentration in the stacking direction of the nitride-based semiconductor light-emitting device according to Comparative Example 1 and the present embodiment, respectively. Figure 3 as well as Figure 4 The intensity distribution of light transmitted through the nitride-based semiconductor light-emitting element 100 is also shown. Figure 5 is a line graph showing the attenuation coefficient spectrum in the AlGaN layer. Figure 5 In the case of undoped Al 0.03 Ga 0.97 The N layer is doped with an average concentration of 1.0×10 19 cm -3 MgAl 0.03 Ga 0.97 The attenuation coefficient spectra of the N layer are represented by solid and dashed lines, respectively.

[0085] The nitride-based semiconductor light-emitting device according to Comparative Example 1 is different from the nitride-based semiconductor light-emitting device 100 according to the present embodiment in that it does not include the P-type intermediate layer 110 , but is otherwise identical to the nitride-based semiconductor light-emitting device 100 according to the present embodiment.

[0086] Each nitride-based semiconductor light-emitting element according to Comparative Example 1 and the present embodiment has an electron blocking layer 109 with a large band gap energy. In order to reduce the resistance in the electron blocking layer 109, a high concentration of impurities (Mg) are doped in the electron blocking layer 109. Accordingly, in the manufacturing process of each nitride-based semiconductor light-emitting element, the layers stacked after the stacking process of the electron blocking layer 109 are doped with impurities remaining in the box used for stacking. Figure 3 As shown, in the nitride-based semiconductor light-emitting element of Comparative Example 1, the P-side light guiding layer 111 stacked on the electron blocking layer 109 is doped with a high concentration of impurities that is higher than the design value of the impurity concentration of the P-side light guiding layer 111. In particular, the impurity concentration increases in the region near the electron blocking layer 109 in the P-side light guiding layer 111.

[0087] like Figure 5 As shown in FIG. 1 , in an AlGaN layer such as the P-side optical guiding layer 111, due to the influence of the impurity energy level, the light absorption end (the end of the light absorption wavelength band on the long wavelength side) is shifted to a low energy (i.e., shifted to the long wavelength side). And the amount of low energy shift increases as the impurity concentration increases. Therefore, in an AlGaN layer such as the P-side optical guiding layer 111, which has a relatively small average Al composition ratio, the influence of light absorption (i.e., light loss) caused by an increase in impurity concentration becomes significant.

[0088] In contrast, in the nitride-based semiconductor light-emitting element 100 according to the present embodiment, a P-type intermediate layer 110 having an average band gap energy smaller than that of the electron blocking layer 109 and larger than that of the P-side light guiding layer 111 is provided on the electron blocking layer 109. The average impurity concentration of the P-type intermediate layer 110 is lower than that of the electron blocking layer 109 and higher than that of the P-side light guiding layer 111.

[0089] Thus, the nitride-based semiconductor light-emitting element 100 according to the present embodiment has a P-type intermediate layer 110 having an average band gap energy greater than that of the P-side light-guiding layer 111 in the region where the impurity concentration of the electron blocking layer 109 increases. Therefore, compared with the nitride-based semiconductor light-emitting element according to Comparative Example 1, the light absorption end of the region can be shifted to the high energy side (short wavelength side). Therefore, in the nitride-based semiconductor light-emitting element 100 according to the present embodiment, light absorption in the region can be suppressed compared with the nitride-based semiconductor light-emitting element according to Comparative Example 1. Therefore, the nitride-based semiconductor light-emitting element 100 according to the present embodiment can reduce the Al component ratio of each layer such as the P-side light-guiding layer 111 and the P-type cladding layer 112, and can suppress light loss.

[0090] Furthermore, in the nitride-based semiconductor light-emitting device 100 , the average band gap energy of the P-type intermediate layer 110 may be greater than or equal to the average band gap energy of the P-type cladding layer 112 .

[0091] According to this, since the light absorption edge in the P-type intermediate layer 110 can be further shifted to the higher energy side, the light loss in the P-type intermediate layer 110 can be further suppressed.

[0092] Furthermore, in the nitride-based semiconductor light-emitting element 100 , the thickness of the P-type intermediate layer 110 may be greater than 10 nm.

[0093] The influence of residual impurities is reduced in the upper region at a certain distance or more from the electron blocking layer 109. For example, in the upper region at a distance of 10 nm or more from the electron blocking layer 109, the impurity concentration can be reduced by 20% or more relative to the impurity concentration in the interface above the electron blocking layer 109. Therefore, by making the film thickness of the P-type intermediate layer 110 more than 10 nm, it is possible to suppress light loss due to residual impurities.

[0094] Furthermore, in the upper region 20 nm or more from the electron blocking layer 109 , the impurity concentration can be reduced to less than half of the impurity concentration in the interface above the electron blocking layer 109 .

[0095] Therefore, since the film thickness of the P-type intermediate layer 110 is greater than or equal to 20 nm, light loss due to the remaining impurities can be sufficiently suppressed.

[0096] Furthermore, in the nitride-based semiconductor light-emitting device 100, the P-type intermediate layer 110 is AlGaN. In other words, the composition of the P-type intermediate layer 110 is Al x Ga 1-x N(0<x<1). The average Al composition ratio of the P-type intermediate layer 110 may be greater than 3%.

[0097] Thus, by using an AlGaN layer having an average Al composition ratio of 3% or more as the P-type intermediate layer 110 , the average band gap energy can be increased to a level that can sufficiently suppress the absorption of light in the ultraviolet wavelength range.

[0098] Furthermore, in the nitride-based semiconductor light-emitting element 100, the average Al composition ratio of each of the N-type cladding layer 104, the N-side light guiding layer 706, the P-type intermediate layer 110, the P-side light guiding layer 111, and the P-type cladding layer 112 is less than 10%.

[0099] According to this, the stress of the entire nitride-based semiconductor light-emitting element 100 and the internal stress caused by lattice mismatch can be reduced. Accordingly, in the manufacturing process of the nitride-based semiconductor light-emitting element 100, the damage and cracking of the wafer on which the semiconductor stack 100S is formed are reduced. In addition, the defects generated inside the nitride-based semiconductor light-emitting element 100 are reduced. Therefore, the yield rate of the nitride-based semiconductor light-emitting element 100 can be improved.

[0100] Furthermore, the nitride-based semiconductor light-emitting element 100 may include a ridge portion 11R extending in the light propagation direction (that is, in a direction parallel to the Y-axis direction in each figure).

[0101] This allows the current supplied to the nitride-based semiconductor light-emitting element 100 to be confined within the ridge portion 11R, and also allows an optical waveguide to be formed along the ridge portion 11R.

[0102] Furthermore, in the nitride-based semiconductor light-emitting device 100, the side surface of the ridge portion 11R may be inclined relative to the main surface 101a of the substrate 101. The effect of the configuration of the ridge portion 11R will be described in detail below. Figure 6 as well as Figure 7 to explain. Figure 6 1 is a schematic cross-sectional view showing the shape of the side surface 11Rs of the ridge portion 11R according to the present embodiment. Figure 6 The outline of the ridge 11R is shown. Figure 7 This is a line graph showing the relationship between the order of the transverse mode of the laser beam and the waveguide loss in a nitride-based semiconductor light-emitting element. Figure 7 , the simulation results of waveguide loss in a nitride-based semiconductor light-emitting device having a waveguide structure substantially equivalent to that of the nitride-based semiconductor light-emitting device 100 according to the present embodiment are shown. Figure 7 FIG. 1 shows the waveguide losses when the inclination angle θr of the side surface 11Rs of the ridge portion 11R is set to 50 degrees, 60 degrees, 70 degrees, 80 degrees, and 90 degrees. In addition, since there is no substantial difference in the waveguide losses when the inclination angle θr is 80 degrees and 90 degrees, Figure 7The waveguide losses at 80 degrees to 90 degrees are combined to express this.

[0103] like Figure 6 As shown, the inclination angle θr of the side surface 11Rs of the ridge portion 11R (the end surface of the ridge portion 11R in the X-axis direction) relative to the main surface 101a of the substrate 101 is defined. Figure 6 The XY plane shown is a plane parallel to the main surface 101 a of the substrate 101 .

[0104] like Figure 7 As shown, overall, there is a tendency that the waveguide loss increases with the increase of the mode order, and in the low-order mode (such as the zero-order mode), the waveguide loss is not affected by the tilt angle θr and is the same value. The tendency related to the tilt angle θr will be shown below. When the tilt angle θr is greater than 80 degrees, the waveguide loss does not change much relative to the mode order. When the tilt angle θr is less than 80 degrees, the waveguide loss of the high-order mode light (for example, the 12th-order mode light) increases compared to the case where the tilt angle θr is greater than 80 degrees. In particular, when the tilt angle θr is 70 degrees, the waveguide loss of the 12th-order mode light becomes the largest compared to other tilt angles. In addition, when the tilt angle θr is 50 degrees, the loss of intermediate-order mode light such as the 4th-order mode light and the 7th-order mode light increases, showing a waveguide loss greater than that of other angles. As in the nitride-based semiconductor light-emitting device 100 according to the present embodiment, when the average Al composition ratio of the N-type cladding layer 104 is small (e.g., less than 10%) and the film thickness is relatively small, a substrate mode in which light propagates in the substrate 101 is likely to occur. Therefore, in the nitride-based semiconductor light-emitting device 100 according to the present embodiment, the above-mentioned waveguide loss becomes significant.

[0105] Here, high-order mode light such as the 12th-order mode light causes a nonlinear bending portion (so-called bending) to occur in the line graph showing the current-light output (IL) characteristics of the nitride-based semiconductor light-emitting element 100 .

[0106] like Figure 7As shown, for example, by making the inclination angle θr greater than 60 degrees and less than 80 degrees, the waveguide loss of the high-order mode light can be increased and the waveguide loss of the intermediate-order mode light can be suppressed. That is, by reducing the abundance of the high-order mode light while suppressing the waveguide loss of the low-order mode light and the intermediate-order mode light, the occurrence of the bend in the current-light output characteristic can be suppressed. Furthermore, by reducing the abundance of the high-order mode light, the occurrence of the substrate mode can be suppressed, and the anti-waveguide mode light leaking from the side 11Rs of the ridge 11R to the outside of the ridge 11R can be suppressed. Furthermore, by reducing the abundance of the high-order mode light, the horizontal diffusion angle (the diffusion angle in the XY plane) of the output light of the nitride-based semiconductor light-emitting element 100 can be reduced.

[0107] Furthermore, the inclination angle θr may be not less than 60 degrees and not more than 75 degrees. This can further reduce the abundance of high-order mode light.

[0108] The ridge portion 11R having such an inclination angle θr can be realized by the following method.

[0109] In general, nitride semiconductors can be etched by chlorine radicals and ions. Specifically, a chlorine-containing gas is plasmatized and irradiated to a nitride semiconductor by an ISM (Inductively Super Magnetron: with a magnetic field) method or an ICP (Inductively Coupled Plasma: inductively coupled plasma) method. In the etching by the chlorine ions contained in the plasma, the anisotropy is high. Therefore, etching with high verticality can be achieved by etching by chlorine ions. However, in the etching by chlorine radicals, the isotropy is high. In the above method, by changing the pressure or the applied voltage, the abundance of chlorine ions and chlorine radicals or the kinetic energy of chlorine ions can be controlled. Accordingly, the balance between anisotropic etching and isotropic etching can be controlled to obtain the desired tilt angle θr.

[0110] Here, the nitride-based semiconductor light-emitting element 100 involved in this embodiment has the following additional effect. If a P-type intermediate layer 110 having a refractive index smaller than that of the P-side light-guiding layer 111 is arranged between the electron blocking layer 109 and the P-side light-guiding layer 111, a light-confining function is also provided at a position closer to the active layer 107 than the P-type cladding layer 112, and the center of the light distribution is shifted toward the N side (i.e., toward the N-type cladding layer 104) compared to the case where there is no P-type intermediate layer 110, and the effective refractive index difference ΔN is reduced. This shift of the light distribution toward the N side will substantially reduce the gain, resulting in an increase in the threshold current. In addition, as the effective refractive index difference ΔN decreases, the higher-order modes in the waveguide become unstable, which causes bending.

[0111] Therefore, when one wants to reduce the influence of the P-type intermediate layer 110 on the light distribution, when the Al component ratio of the P-type cladding layer 112 is large, the film thickness of the P-type intermediate layer 110 can be made thinner, and when the Al component ratio of the P-type cladding layer 112 is small, the film thickness of the P-type intermediate layer 110 can be made thicker. As shown in the present embodiment, when the Al component ratio of the P-side light guiding layer 111 is 0.03 (i.e., 3%) and the Al component ratio of the P-type cladding layer 112 is 0.065 (i.e., 6.5%), when the Al component ratio of the P-type intermediate layer 110 is greater than 0.050 and less than 0.080 (i.e., greater than 5.0% and less than 8.0%), the film thickness of the P-type intermediate layer 110 can be greater than 5nm and less than 20nm, and when the Al component ratio of the P-type intermediate layer 110 is greater than 0.030 and less than 0.050 (i.e., greater than 3.0% and less than 5.0%), the film thickness of the P-type intermediate layer 110 can be greater than 20nm and less than 40nm.

[0112] In particular, when the Al composition ratio of the P-type intermediate layer 110 is higher than the Al composition ratio of the P-type cladding layer 112 (that is, when the Al composition ratio of the P-type intermediate layer 110 is greater than 0.065 and less than 0.080), the film thickness of the P-type intermediate layer 110 can be greater than 5nm and less than 10nm.

[0113] (Implementation Method 2)

[0114] The nitride-based semiconductor light-emitting element according to Embodiment 2 is described. The nitride-based semiconductor light-emitting element according to this embodiment differs from the nitride-based semiconductor light-emitting element 100 according to Embodiment 1 in the structure of the P-type intermediate layer, and the other structures are the same. The following describes the nitride-based semiconductor light-emitting element according to this embodiment, focusing on the differences from the nitride-based semiconductor light-emitting element 100 according to Embodiment 1. Figure 8 to explain.

[0115] Figure 8 2 is a schematic line graph showing the distribution of the band gap energy and impurity concentration of the nitride-based semiconductor light-emitting element according to this embodiment in the stacking direction. Figure 8 As shown, the nitride-based semiconductor light-emitting element according to this embodiment includes a P-type intermediate layer 210 .

[0116] The difference between the P-type intermediate layer 210 and the P-type intermediate layer 110 according to the first embodiment is that the average band gap energy is smaller than the average band gap energy of the P-type cladding layer 112. In this embodiment, the P-type intermediate layer 210 is doped with an average concentration of 1.0×10 19 cm -3 The film thickness of Mg is 20nm P-type Al 0.05 Ga 0.95N layers.

[0117] The nitride-based semiconductor light-emitting device according to the present embodiment having the above-described structure can also achieve the same effects as those of the nitride-based semiconductor light-emitting device 100 according to the first embodiment.

[0118] Furthermore, in the nitride-based semiconductor light-emitting device according to the present embodiment, the average band gap energy of the P-type intermediate layer 210 is smaller than the average band gap energy of the P-type cladding layer 112 .

[0119] Thus, the average refractive index of the P-type intermediate layer 210 can be made larger than the average refractive index of the P-type cladding layer 112. Therefore, in the present embodiment, the P-type intermediate layer 210 also functions as a light guiding layer. Thus, the light loss in the nitride-based semiconductor light-emitting element can be reduced without reducing the function of confining light in the active layer 107.

[0120] Furthermore, as shown in this embodiment, by increasing the average refractive index of the P-type intermediate layer 210, it is possible to suppress the reduction in the light confinement function in the active layer 107 that is caused by the increase in the film thickness of the P-type intermediate layer 210. Therefore, even in the case where the region with a high impurity concentration is large, by increasing the film thickness of the P-type intermediate layer 210, it is possible to reduce light loss while suppressing the reduction in the light confinement function.

[0121] (Implementation 3)

[0122] The nitride-based semiconductor light-emitting element according to Embodiment 3 is described. The nitride-based semiconductor light-emitting element according to this embodiment differs from the nitride-based semiconductor light-emitting element 100 according to Embodiment 1 in the relative position of the lower end of the ridge portion and the P-type intermediate layer 110, and the other structures are the same. The nitride-based semiconductor light-emitting element according to this embodiment is described below, focusing on the differences from the nitride-based semiconductor light-emitting element 100 according to Embodiment 1. Fig. 9 to explain.

[0123] Fig. 9 It is a schematic cross-sectional view showing the overall structure of a nitride-based semiconductor light-emitting element 300 according to the present embodiment. Fig. 9 Shows that Figure 2 It is a cross section of the nitride-based semiconductor light-emitting element 300 at the same position.

[0124] like Fig. 9As shown, the nitride-based semiconductor light-emitting element 300 involved in this embodiment is the same as the nitride-based semiconductor light-emitting element 100 involved in Embodiment 1, and includes a substrate 101, a semiconductor stack 100S, a current blocking layer 120, a P-side electrode 131, a close-fitting layer 132, a pad electrode 133, and an N-side electrode 140.

[0125] In the present embodiment, a ridge 21R is formed in the contact layer 113, the P-type cladding layer 112, the P-side light guiding layer 111, and the P-type intermediate layer 110. In addition, two grooves 21T are formed in the contact layer 113, the P-type cladding layer 112, the P-side light guiding layer 111, and the P-type intermediate layer 110, which are arranged along the ridge 21R and extend in the Y-axis direction. As described above, in the nitride-based semiconductor light-emitting element 300 involved in the present embodiment, the lower end of the ridge 21R is located in the P-type intermediate layer 110. In other words, at least a portion of the P-type intermediate layer 110 is arranged on the ridge 21R. In the present embodiment, the distance dc between the lower end of the ridge 21R and the electron blocking layer 109 is greater than 0 and less than 20 nm.

[0126] Even in the nitride-based semiconductor light-emitting device 300 according to the present embodiment having the above-described structure, the same effects as those of the nitride-based semiconductor light-emitting device 100 according to the first embodiment can be achieved.

[0127] In this embodiment, at least a portion of the P-type intermediate layer 110 is disposed on the ridge 21R. Accordingly, the P-side optical guide layer 111 located above the P-type intermediate layer 110 is disposed within the ridge 21R. For this reason, the refractive index of the current blocking layer 120 located on the ridge 21R and the side of the ridge 21R is smaller than that of the ridge 21R, so that the light confinement function in the lateral direction (the X-axis direction of each figure) can be improved. Therefore, stable multi-mode oscillation can be achieved in the nitride-based semiconductor light-emitting element 300.

[0128] In addition, in the present embodiment, a surface energy level based on dangling bonds (non-shared electrons) is formed on the surface of the P-type intermediate layer 110 corresponding to the bottom and side surfaces of the groove 21T formed by etching. Accordingly, the band gap of the region in the P-type intermediate layer 110 that is in contact with the bottom and side surfaces of the groove 21T becomes smaller. In addition, by doping Mg in the P-type intermediate layer 110, the absorption range in the absorption coefficient spectrum is shifted to a long wavelength. In response to the absorption loss caused by these reasons, as shown in the present embodiment, by adopting a P-type intermediate layer 110 having an Al composition ratio greater than the Al composition ratio of the P-side optical guiding layer 111, it is possible to have a P-type intermediate layer 110 having an average band gap energy greater than that of the P-side optical guiding layer 111. Therefore, even when the lower end of the ridge 21R is arranged in the P-type intermediate layer 110, the absorption loss in the region in contact with the groove 21T in the P-type intermediate layer 110 can be suppressed.

[0129] (Implementation 4)

[0130] The nitride-based semiconductor light-emitting element according to Embodiment 4 is described. The nitride-based semiconductor light-emitting element according to this embodiment differs from the nitride-based semiconductor light-emitting element 100 according to Embodiment 1 in the structure of the P-type intermediate layer, and the other structures are the same. The following describes the nitride-based semiconductor light-emitting element according to this embodiment, focusing on the differences from the nitride-based semiconductor light-emitting element 100 according to Embodiment 1. Fig.10 to explain.

[0131] Fig.10 2 is a schematic line graph showing the distribution of the band gap energy and impurity concentration of the nitride-based semiconductor light-emitting element according to this embodiment in the stacking direction. Fig.10 As shown, the nitride-based semiconductor light-emitting element according to this embodiment includes a P-type intermediate layer 410 .

[0132] The P-type intermediate layer 410 includes a first P-type intermediate layer 410a and a second P-type intermediate layer 410b disposed above the first P-type intermediate layer 410a and having an average bandgap energy smaller than that of the first P-type intermediate layer 410a. The first P-type intermediate layer 410a has a higher average Al composition ratio than the second P-type intermediate layer 410b.

[0133] In the present embodiment, the average band gap energy of the first P-type intermediate layer 410a is greater than the average band gap energy of the P-type cladding layer 112, and the average band gap energy of the P-type intermediate layer 410 is smaller than the average band gap energy of the P-type cladding layer 112. In addition, the average impurity concentration (average Mg concentration) of the first P-type intermediate layer 410a is greater than the average impurity concentration of the second P-type intermediate layer 410b.

[0134] In this embodiment, the first P-type intermediate layer 410a is doped with an average concentration of 1.3×10 19 cm -3 The film thickness of Mg is 5nm P-type Al 0.08 Ga 0.92 N layer, the second P-type intermediate layer 410b is doped with an average concentration of 9.0×10 18 cm -3 The film thickness of Mg is 15nm P-type Al 0.05 Ga 0.95 N layers.

[0135] The nitride-based semiconductor light-emitting device according to the present embodiment having the above-described structure can also achieve the same effects as those of the nitride-based semiconductor light-emitting device 100 according to the first embodiment.

[0136] In the present embodiment, the P-type intermediate layer 410 includes a first P-type intermediate layer 410 a and a second P-type intermediate layer 410 b disposed above the first P-type intermediate layer 410 a and having an average band gap energy smaller than that of the first P-type intermediate layer 410 a .

[0137] Here, in the P-type intermediate layer 410, due to the influence of the above-mentioned residual impurities, the impurity concentration tends to increase as it approaches the electron blocking layer 109. In an AlGaN layer such as the P-type intermediate layer 410, the higher the impurity concentration, the greater the light absorption. In this embodiment, by providing a first P-type intermediate layer 410a with a large average band gap energy in a region with a high impurity concentration close to the electron blocking layer 109, the light loss in the P-type intermediate layer 410 can be further suppressed.

[0138] Furthermore, in this embodiment, the average bandgap energy of the first P-type intermediate layer 410 a may be greater than the average bandgap energy of the P-type cladding layer 112 , and the average bandgap energy of the P-type intermediate layer 410 may be smaller than the average bandgap energy of the P-type cladding layer 112 .

[0139] In this way, in the P-type intermediate layer 410, by increasing the average band gap energy of the first P-type intermediate layer 410a, especially near the electron blocking layer 109, where the impurity concentration is likely to increase, the light loss in the first P-type intermediate layer 410a can be suppressed. In addition, by making the average band gap energy of the entire P-type intermediate layer 410 smaller than the average band gap energy of the P-type cladding layer 112, a part of the P-type intermediate layer 410 can function as a light guiding layer in the same manner as in Embodiment 2. In addition, by reducing the band gap energy of the P-type intermediate layer 410, the average Al composition ratio of the entire P-type intermediate layer 410 can be reduced. Accordingly, since the proportion of impurities that act as acceptors among the impurities doped in the P-type intermediate layer 410 can be increased, the resistance in the P-type intermediate layer 410 can be suppressed.

[0140] In addition, in the present embodiment, although the P-type intermediate layer 410 has two layers, the first P-type intermediate layer 410a and the second P-type intermediate layer 410b, the P-type intermediate layer 410 may also have three or more layers. For example, the P-type intermediate layer 410 may also have a third P-type intermediate layer disposed above the second P-type intermediate layer 410b and having an average band gap energy smaller than that of the second P-type intermediate layer 410b.

[0141] (Implementation method 5)

[0142] The nitride-based semiconductor light-emitting element according to Embodiment 5 is described. The nitride-based semiconductor light-emitting element according to this embodiment differs from the nitride-based semiconductor light-emitting element 100 according to Embodiment 1 in the structure of the P-type intermediate layer, and the other structures are the same. The following describes the nitride-based semiconductor light-emitting element according to this embodiment, focusing on the differences from the nitride-based semiconductor light-emitting element 100 according to Embodiment 1. Fig.11 to explain.

[0143] Fig.11 2 is a schematic line graph showing the distribution of the band gap energy and impurity concentration of the nitride-based semiconductor light-emitting element according to this embodiment in the stacking direction. Fig.11 As shown, the nitride-based semiconductor light-emitting element according to this embodiment includes a P-type intermediate layer 510 .

[0144] The P-type intermediate layer 510 has a P-type inclined region in which the Al composition ratio decreases as it moves away from the electron blocking layer 109. In this embodiment, the entire P-type intermediate layer 510 is a P-type inclined region. The average band gap energy of the P-type intermediate layer 510 is smaller than the average band gap energy of the P-type cladding layer 112.

[0145] Furthermore, the P-type intermediate layer 510 has an impurity concentration gradient region in which the impurity concentration decreases as the distance from the electron blocking layer 109 increases. In the present embodiment, the entire P-type intermediate layer 510 is an impurity concentration gradient region.

[0146] In this embodiment, the P-type intermediate layer 510 is doped with an average concentration of 1.0×10 19 cm -3 The composition of the P-type intermediate layer 510 at the interface with the electron blocking layer 109 is Al 0.08 Ga 0.92 The composition of the interface between the N,P type intermediate layer 510 and the P side optical guide layer 111 is Al 0.05 Ga 0.95N. The Al composition ratio of the P-type intermediate layer 510 decreases continuously as it moves away from the electron blocking layer 109. Also, the impurity concentration of the P-type intermediate layer 510 increases from 1.5×10 19 cm -3 to 2.0×10 18 cm -3 Continuously lower.

[0147] The nitride-based semiconductor light-emitting device according to the present embodiment having the above-described structure can also achieve the same effects as those of the nitride-based semiconductor light-emitting device 100 according to the first embodiment.

[0148] Furthermore, in the present embodiment, the P-type intermediate layer 510 has a P-type inclined region in which the Al composition ratio decreases as the distance from the electron blocking layer 109 increases.

[0149] Here, in the P-type intermediate layer 510, due to the influence of the above-mentioned residual impurities, the impurity concentration tends to decrease as it moves away from the electron blocking layer 109. Moreover, in an AlGaN layer such as the P-type intermediate layer 510, the higher the impurity concentration, the greater the light absorption. In this embodiment, by having a P-type inclined region in which the Al composition ratio decreases as it moves away from the electron blocking layer 109, the band gap energy can be reduced as it moves away from the electron blocking layer 109. Accordingly, it is possible to suppress light loss in the P-type intermediate layer 510 and reduce the Al composition ratio.

[0150] Furthermore, in the present embodiment, the average band gap energy of the P-type intermediate layer 510 may be smaller than the average band gap energy of the P-type cladding layer 112 .

[0151] According to this, a part of the P-type intermediate layer 510 can function as a light guiding layer as in Embodiment 2. Furthermore, by reducing the band gap energy of the P-type intermediate layer 510, the average Al composition ratio of the entire P-type intermediate layer 510 can be reduced. Therefore, since the proportion of impurities that function as acceptors among the impurities doped in the P-type intermediate layer 510 can be increased, the resistance in the P-type intermediate layer 510 can be suppressed.

[0152] (Implementation 6)

[0153] The nitride-based semiconductor light-emitting element according to Embodiment 6 is described. The nitride-based semiconductor light-emitting element according to this embodiment differs from the nitride-based semiconductor light-emitting element 100 according to Embodiment 1 in the structure of the P-type intermediate layer, and the other structures are the same. The following describes the nitride-based semiconductor light-emitting element according to this embodiment, focusing on the differences from the nitride-based semiconductor light-emitting element 100 according to Embodiment 1. Fig.12 to explain.

[0154] Fig.12 2 is a schematic line graph showing the distribution of the band gap energy and impurity concentration of the nitride-based semiconductor light-emitting element according to this embodiment in the stacking direction. Fig.12 As shown, the nitride-based semiconductor light-emitting element according to this embodiment includes a P-type intermediate layer 610 .

[0155] The P-type intermediate layer 610 has a first P-type intermediate layer 610a having an average band gap energy smaller than that of the P-type cladding layer 112, and a second P-type intermediate layer 610b having an average band gap energy larger than that of the first P-type intermediate layer 610a, which is arranged above the first P-type intermediate layer 610a. In the present embodiment, the average band gap energy of the second P-type intermediate layer 610b is smaller than that of the P-type cladding layer 112. The average Al composition ratio of the first P-type intermediate layer 610a is smaller than the average Al composition ratio of the second P-type intermediate layer 610b.

[0156] Furthermore, the average impurity concentration (average Mg concentration) of the first P-type intermediate layer 610 a is lower than the average impurity concentration of the second P-type intermediate layer 610 b .

[0157] In this embodiment, the first P-type intermediate layer 610a is doped with an average concentration of 5.0×10 18 cm -3 The film thickness of Mg is 10nm P-type Al 0.04 Ga 0.96 N layer, the second P-type intermediate layer 610b is doped with an average concentration of 1.0×10 19 cm -3 The film thickness of Mg is 15nm P-type Al 0.05 Ga 0.95 N layers.

[0158] Even in the nitride-based semiconductor light-emitting element involved in the present embodiment having the above-mentioned structure, since the Mg concentration in the area of ​​the P-type intermediate layer 610 close to the active layer 107, i.e., the area with strong light, is low, the effect of suppressing light loss is greater than that of the nitride-based semiconductor light-emitting element 100 involved in embodiment 1.

[0159] And in this embodiment, the P-type intermediate layer 610 has a first P-type intermediate layer 610a having an average band gap energy smaller than that of the P-type cladding layer 112, and a second P-type intermediate layer 610b arranged above the first P-type intermediate layer 610a having an average band gap energy larger than that of the first P-type intermediate layer 610a.

[0160] As described above, due to the influence of residual impurities, the impurity concentration in the layer stacked on the electron blocking layer 109 is likely to increase. This effect is likely to occur when the film thickness is about 80nm or more and 100nm or less. By configuring the P-type intermediate layer 610 in most of the region where the impurity concentration is likely to increase, light loss can be suppressed. However, when the refractive index of the P-type intermediate layer 610 is large and the film thickness of the P-type intermediate layer 610 is large, the reduction in the light confinement function of the active layer 107 becomes significant.

[0161] In the present embodiment, the average band gap energy of the first P-type intermediate layer 610a is made smaller than the average band gap energy of the P-type cladding layer 112, so that the average refractive index of the first P-type intermediate layer 610a is larger than the average refractive index of the P-type cladding layer 112. Accordingly, the first P-type intermediate layer 610a that functions as a light guiding layer is arranged in a region of the P-type intermediate layer 610 close to the active layer 107. Therefore, it is possible to suppress the reduction of the light confinement function of the active layer 107 in the nitride-based semiconductor light-emitting element involved in the present embodiment.

[0162] Furthermore, the average impurity concentration in the first P-type intermediate layer 610a may be lower than the average impurity concentration in the second P-type intermediate layer 610b. Accordingly, since the light absorption end caused by the impurities in the first P-type intermediate layer 610a can be suppressed from shifting toward the long wavelength side, the light loss in the first P-type intermediate layer 610a can be suppressed.

[0163] Furthermore, the thickness of the first P-type intermediate layer 610 a may be less than 15 nm, thereby suppressing light loss in the first P-type intermediate layer 610 a.

[0164] In addition, in the present embodiment, although the P-type intermediate layer 610 has two layers, the first P-type intermediate layer 610a and the second P-type intermediate layer 610b, the P-type intermediate layer 610 may also have more than three layers. For example, the P-type intermediate layer 610 may also have a third P-type intermediate layer disposed above the second P-type intermediate layer 610b and having an average band gap energy smaller than that of the second P-type intermediate layer 610b.

[0165] (Implementation 7)

[0166] The nitride-based semiconductor light-emitting element according to Embodiment 7 is described. The nitride-based semiconductor light-emitting element according to this embodiment differs from the nitride-based semiconductor light-emitting element 100 according to Embodiment 1 in that it has an N-type intermediate layer, and the other structures are the same. The following describes the nitride-based semiconductor light-emitting element according to this embodiment, focusing on the differences from the nitride-based semiconductor light-emitting element 100 according to Embodiment 1. Fig.13 as well as Fig.14 to explain.

[0167] Fig.13 It is a schematic cross-sectional view showing the overall structure of a nitride-based semiconductor light-emitting element 700 according to the present embodiment. Fig.13 It is shown in Figure 2 It is a cross section of the nitride-based semiconductor light-emitting element 700 at the same position. Fig.14 It is a schematic line graph showing the distribution of the band gap energy and the impurity concentration in the stacking direction of the nitride-based semiconductor light-emitting element 700 according to the present embodiment.

[0168] like Fig.13 As shown, the nitride-based semiconductor light-emitting element 700 according to the present embodiment includes a substrate 101 , a semiconductor stack 700S, a current blocking layer 120 , a P-side electrode 131 , an adhesion layer 132 , a pad electrode 133 , and an N-side electrode 140 .

[0169] The semiconductor stack 700S has a base layer 102, a buffer layer 103, an N-type cladding layer 104, an N-type intermediate layer 705, an N-side light guiding layer 706, an active layer 107, an electron blocking layer 109, a P-type intermediate layer 110, a P-side light guiding layer 111, a P-type cladding layer 112, and a contact layer 113.

[0170] The N-type intermediate layer 705 is a nitride semiconductor layer containing Al disposed above the N-type cladding layer 104. The average band gap energy of the N-type intermediate layer 705 is larger than the average band gap energy of the N-side optical guiding layer 706 and smaller than the average band gap energy of the N-type cladding layer 104. The average Al composition ratio of the N-type intermediate layer 705 can be less than 10%. The average impurity concentration of the N-type intermediate layer 705 is lower than the average impurity concentration of the N-type cladding layer 104 and higher than the average impurity concentration of the N-side optical guiding layer 706. In this embodiment, the N-type intermediate layer 705 is doped with an average concentration of 1.0×10 18 cm -3 The Si film thickness is 20nm N-type Al 0.05 Ga 0.95 N layers.

[0171] The N-side light guiding layer 706 is a nitride-based semiconductor layer containing Al disposed above the N-type intermediate layer 705. The N-side light guiding layer 706 has a larger average refractive index and a smaller average band gap energy than the N-type cladding layer 104 and the N-type intermediate layer 705. In this embodiment, the N-side light guiding layer 706 is an undoped Al layer with a film thickness of 187 nm. 0.03 Ga 0.97 N layer: The thickness of the N-type intermediate layer 705 is greater than 20 nm.

[0172] The effects of the nitride-based semiconductor light-emitting element 700 according to this embodiment will be described below.

[0173] Even when the N-side optical guiding layer 706 as an undoped AlGaN layer is directly stacked on the AlGaN layer doped with Si as an N-type impurity, that is, the N-type cladding layer 104, although the influence of the P-type impurity residue is small, there is still an influence caused by the impurity residue. For this reason, the impurity concentration in the N-side optical guiding layer 706, especially in the area near the N-type cladding layer 104, will be higher than the designed value. Moreover, even in the N-type AlGaN layer, as in the P-type AlGaN layer, the light absorption end will shift to the long wavelength side according to the impurity concentration. Therefore, the light loss in the N-side optical guiding layer 706 will increase.

[0174] The nitride-based semiconductor light-emitting device 700 according to the present embodiment includes an N-type intermediate layer 705 having an average band gap energy greater than that of the N-side light-guiding layer 706 in a region where the impurity concentration on the N-type cladding layer 104 is likely to increase, thereby being able to suppress light absorption in the same manner as the P-type intermediate layer 110. In this way, the nitride-based semiconductor light-emitting device 700 according to the present embodiment can reduce the Al composition ratio of each layer such as the N-side light-guiding layer 706 and the N-type cladding layer 104, while suppressing light loss.

[0175] Furthermore, in the nitride-based semiconductor light-emitting element 700, the thickness of the N-type intermediate layer 705 may be greater than 20 nm.

[0176] The influence of the residual impurities is reduced in the region above 20 nm or more from the N-type cladding layer 104. For example, in the region above 20 nm or more from the N-type cladding layer 104, the impurity concentration can be reduced to less than half of the impurity concentration in the interface above the N-type cladding layer 104. Therefore, by making the film thickness of the N-type intermediate layer 705 greater than 20 nm, the light loss caused by the residual impurities can be fully suppressed.

[0177] Furthermore, in the nitride-based semiconductor light-emitting device 700, the N-type intermediate layer 705 is AlGaN. In other words, the composition of the N-type intermediate layer 705 is Al y Ga 1-y N(0<y<1) The average Al composition ratio of the N-type intermediate layer 705 may be greater than 3%.

[0178] In this way, by using an AlGaN layer having an average Al composition ratio of 3% or more as the N-type intermediate layer 705 , the average band gap energy can be increased to a level that can sufficiently suppress the absorption of light in the ultraviolet wavelength range.

[0179] Furthermore, in the nitride-based semiconductor light-emitting element 700, the average Al composition ratio of each of the N-type cladding layer 104, the N-side light guiding layer 706, the N-type intermediate layer 705, the P-side light guiding layer 111, and the P-type cladding layer 112 is less than 10%.

[0180] According to this, the stress in the entire nitride-based semiconductor light-emitting element 700 and the internal stress caused by lattice mismatch can be reduced. Accordingly, in the manufacturing process of the nitride-based semiconductor light-emitting element 700, the breakage and cracking of the wafer on which the semiconductor stack 700S is formed are reduced. In addition, the defects generated inside the nitride-based semiconductor light-emitting element 700 are also reduced. Therefore, the yield rate of the nitride-based semiconductor light-emitting element 700 can be improved.

[0181] (Implementation 8)

[0182] The nitride-based semiconductor light-emitting element according to Embodiment 8 is described. The nitride-based semiconductor light-emitting element according to this embodiment differs from the nitride-based semiconductor light-emitting element 700 according to Embodiment 7 in the structure of the N-type intermediate layer, and the other structures are the same. The following describes the nitride-based semiconductor light-emitting element according to this embodiment, focusing on the differences from the nitride-based semiconductor light-emitting element 700 according to Embodiment 7. Fig.15 to explain.

[0183] Fig.15 2 is a schematic line graph showing the distribution of the band gap energy and impurity concentration of the nitride-based semiconductor light-emitting element according to this embodiment in the stacking direction. Fig.15 As shown, the nitride-based semiconductor light-emitting element according to this embodiment includes an N-type intermediate layer 805 .

[0184] The N-type intermediate layer 805 includes a first N-type intermediate layer 805a and a second N-type intermediate layer 805b disposed above the first N-type intermediate layer 805a and having an average bandgap energy smaller than that of the first N-type intermediate layer 805a. The first N-type intermediate layer 805a has a higher average Al composition ratio than the second N-type intermediate layer 805b.

[0185] In this embodiment, the average impurity concentration (average Si concentration) of the first N-type intermediate layer 805 a is higher than the average impurity concentration of the second N-type intermediate layer 805 b .

[0186] In this embodiment, the first N-type intermediate layer 805a is doped with an average concentration of 1.0×10 18 cm -3 The Si film thickness is 10nm N-type Al 0.06 Ga 0.94N layer, the second N-type intermediate layer 805b is doped with an average concentration of 8.0×10 17 cm -3 The Si film thickness is 10nm N-type Al 0.05 Ga 0.95 N layers.

[0187] Even in the nitride-based semiconductor light-emitting element according to this embodiment having the above-described structure, the same effects as those of the nitride-based semiconductor light-emitting element 700 according to Embodiment 7 can be achieved.

[0188] In this embodiment, the N-type intermediate layer 805 includes a first N-type intermediate layer 805 a and a second N-type intermediate layer 805 b disposed above the first N-type intermediate layer 805 a and having an average band gap energy smaller than that of the first N-type intermediate layer 805 a .

[0189] Here, in the N-type intermediate layer 805, due to the influence of the above-mentioned residual impurities, the impurity concentration tends to increase as it approaches the N-type cladding layer 104. In an AlGaN layer such as the N-type intermediate layer 805, the higher the impurity concentration, the greater the light absorption. In this embodiment, by providing a first N-type intermediate layer 805a with a large average band gap energy in a region with a high impurity concentration near the N-type cladding layer 104, the light loss in the N-type intermediate layer 805 can be further suppressed.

[0190] In addition, in the present embodiment, although the N-type intermediate layer 805 includes two layers, the first N-type intermediate layer 805a and the second N-type intermediate layer 805b, the N-type intermediate layer 805 may also include three or more layers. For example, the N-type intermediate layer 805 may further include a third N-type intermediate layer disposed above the second N-type intermediate layer 805b and having an average band gap energy smaller than that of the second N-type intermediate layer 805b.

[0191] (Implementation method 9)

[0192] The nitride-based semiconductor light-emitting element according to Embodiment 9 is described. The nitride-based semiconductor light-emitting element according to this embodiment differs from the nitride-based semiconductor light-emitting element 700 according to Embodiment 7 in the structure of the N-type intermediate layer, and the other structures are the same. The following describes the nitride-based semiconductor light-emitting element according to this embodiment, focusing on the differences from the nitride-based semiconductor light-emitting element 700 according to Embodiment 7. Fig.16 to explain.

[0193] Fig.16 2 is a schematic line graph showing the distribution of the band gap energy and impurity concentration of the nitride-based semiconductor light-emitting element according to this embodiment in the stacking direction. Fig.16As shown, the nitride-based semiconductor light-emitting element according to this embodiment includes an N-type intermediate layer 905 .

[0194] The N-type intermediate layer 905 has an N-type inclined region in which the Al composition ratio decreases as it moves away from the N-type cladding layer 104. In this embodiment, the entire N-type intermediate layer 905 is an N-type inclined region. The average bandgap energy of the N-type intermediate layer 905 is smaller than that of the N-type cladding layer 104.

[0195] Furthermore, the N-type intermediate layer 905 has an impurity concentration gradient region in which the impurity concentration decreases as the distance from the N-type cladding layer 104 increases. In the present embodiment, the entire N-type intermediate layer 905 is an impurity concentration gradient region.

[0196] In this embodiment, the N-type intermediate layer 905 is doped with an average concentration of 8.0×10 17 cm -3 The composition of the interface between the N-type intermediate layer 905 and the N-type cladding layer 104 is Al 0.065 Ga 0.935 The composition at the interface between the N-type intermediate layer 905 and the N-side optical guide layer 706 is Al 0.05 Ga 0.95 N. The Al composition ratio of the N-type intermediate layer 905 decreases continuously as it is away from the N-type cladding layer 104. Also, the impurity concentration of the N-type intermediate layer 905 decreases continuously as it is away from the N-type cladding layer 104.

[0197] Even in the nitride-based semiconductor light-emitting element according to this embodiment having the above-described structure, the same effects as those of the nitride-based semiconductor light-emitting element 700 according to Embodiment 7 can be achieved.

[0198] Furthermore, in the present embodiment, the N-type intermediate layer 905 has an N-type inclined region in which the Al composition ratio decreases as the distance from the N-type cladding layer 104 increases.

[0199] Here, in the N-type intermediate layer 905, due to the influence of the above-mentioned residual impurities, the impurity concentration tends to decrease as it moves away from the N-type cladding layer 104. In addition, in an AlGaN layer such as the N-type intermediate layer 905, the higher the impurity concentration, the greater the light absorption. In this embodiment, by having an N-type inclined region in which the Al composition ratio decreases as it moves away from the N-type cladding layer 104, the band gap energy can be reduced as it moves away from the N-type cladding layer 104. Accordingly, it is possible to suppress light loss in the N-type intermediate layer 905 and reduce the Al composition ratio.

[0200] (Implementation 10)

[0201] The nitride-based semiconductor light-emitting element according to Embodiment 10 is described. The nitride-based semiconductor light-emitting element according to this embodiment differs from the nitride-based semiconductor light-emitting element 700 according to Embodiment 7 in the structure of the N-type intermediate layer, and the other structures are the same. The following describes the nitride-based semiconductor light-emitting element according to this embodiment, focusing on the differences from the nitride-based semiconductor light-emitting element 700 according to Embodiment 7. Fig.17 to explain.

[0202] Fig.17 2 is a schematic line graph showing the distribution of the band gap energy and impurity concentration of the nitride-based semiconductor light-emitting element according to this embodiment in the stacking direction. Fig.17 As shown, the nitride-based semiconductor light-emitting element according to this embodiment includes an N-type intermediate layer 1005 .

[0203] The N-type intermediate layer 1005 includes a first N-type intermediate layer 1005a having an average band gap energy smaller than that of the N-type cladding layer 104, and a second N-type intermediate layer 1005b having an average band gap energy larger than that of the first N-type intermediate layer 1005a and arranged above the first N-type intermediate layer 1005a. In the present embodiment, the average band gap energy of the second N-type intermediate layer 1005b is smaller than that of the N-type cladding layer 104. The average Al composition ratio of the first N-type intermediate layer 1005a is smaller than that of the second N-type intermediate layer 1005b.

[0204] Furthermore, the average impurity concentration (average Si concentration) of the first N-type intermediate layer 1005 a is lower than the average impurity concentration of the second N-type intermediate layer 1005 b .

[0205] In this embodiment, the first N-type intermediate layer 1005a is doped with an average concentration of 8.0×10 17 cm -3 The Si film thickness is 10nm N-type Al 0.05 Ga 0.95 N layer, the second N-type intermediate layer 1005b is doped with an average concentration of 1.0×10 18 cm -3 The Si film thickness is 10nm N-type Al 0.06 Ga 0.94 N layers.

[0206] Even in the nitride-based semiconductor light-emitting element according to this embodiment having the above-described structure, the same effects as those of the nitride-based semiconductor light-emitting element 700 according to Embodiment 7 can be achieved.

[0207] In this embodiment, the N-type intermediate layer 1005 includes a first N-type intermediate layer 1005a having an average bandgap energy smaller than that of the N-type cladding layer 104, and a second N-type intermediate layer 1005b having an average bandgap energy larger than that of the first N-type intermediate layer 1005a and disposed above the first N-type intermediate layer 1005a.

[0208] As described above, due to the influence of residual impurities, the impurity concentration in the layer stacked on the N-type cladding layer 104 is likely to increase. This influence is likely to occur in a range of film thickness of about 20 nm or more. By configuring the N-type intermediate layer 1005 in most of the region where the impurity concentration is likely to increase, light loss can be suppressed. However, when the refractive index of the N-type intermediate layer 1005 is large and the film thickness of the N-type intermediate layer 1005 is large, the reduction in the light confinement function of the active layer 107 becomes significant.

[0209] In this embodiment, the average band gap energy of the first N-type intermediate layer 1005a is made smaller than the average band gap energy of the N-type cladding layer 104, so that the average refractive index of the first N-type intermediate layer 1005a is made larger than the average refractive index of the N-type cladding layer 104. Accordingly, the first N-type intermediate layer 1005a that functions as a light guiding layer is arranged in the N-type intermediate layer 1005. Therefore, in the nitride-based semiconductor light-emitting element according to this embodiment, it is possible to suppress the reduction of the light confinement function of the active layer 107.

[0210] Furthermore, the average impurity concentration in the first N-type intermediate layer 1005a may be lower than the average impurity concentration in the second N-type intermediate layer 1005b. Accordingly, since the light absorption end caused by the impurities in the first N-type intermediate layer 1005a can be suppressed from shifting to the long wavelength side, the light loss in the first N-type intermediate layer 1005a can be suppressed.

[0211] Furthermore, the thickness of the first N-type intermediate layer 1005a can be less than 15 nm, thereby suppressing light loss in the first N-type intermediate layer 1005a.

[0212] In addition, in the present embodiment, although the N-type intermediate layer 1005 includes two layers, the first N-type intermediate layer 1005a and the second N-type intermediate layer 1005b, the N-type intermediate layer 1005 may also include three or more layers. For example, the N-type intermediate layer 1005 may also include a third N-type intermediate layer disposed above the second N-type intermediate layer 1005b and having an average band gap energy smaller than that of the second N-type intermediate layer 1005b.

[0213] (Implementation 11)

[0214] The nitride-based semiconductor light-emitting element according to Embodiment 11 is described. The nitride-based semiconductor light-emitting element according to this embodiment differs from the nitride-based semiconductor light-emitting element 100 according to Embodiment 1 mainly in the layer structure between the active layer and the electron blocking layer. The nitride-based semiconductor light-emitting element according to this embodiment is described below, centering on the differences from the nitride-based semiconductor light-emitting element 100 according to Embodiment 1.

[0215] [11-1. Overall composition]

[0216] use Fig.18 as well as Fig.19 The overall structure of the nitride-based semiconductor light-emitting element according to this embodiment will be described. Fig.18 This is a schematic cross-sectional view showing the overall structure of a nitride-based semiconductor light-emitting element 1100 according to this embodiment. Fig.18 Shown with Figure 2 It is a cross section of the nitride-based semiconductor light-emitting element 1100 at the same position. Fig.19 It is a schematic line graph showing the distribution of the band gap energy and the impurity concentration in the stacking direction of the nitride-based semiconductor light-emitting element 1100 involved in this embodiment.

[0217] like Fig.18 As shown, the nitride-based semiconductor light-emitting element 1100 according to the present embodiment includes a substrate 101 , a semiconductor stack 1100S, a current blocking layer 120 , a P-side electrode 131 , an adhesion layer 132 , a pad electrode 133 , and an N-side electrode 140 .

[0218] The semiconductor stack 1100S has a base layer 102, a buffer layer 103, an N-type cladding layer 1104, an N-side light guiding layer 106, an active layer 1107, a lower P-side light guiding layer 1111a, a lower P-side intermediate layer 1110a, an electron blocking layer 109, a P-type intermediate layer 1110, a P-side light guiding layer 111, a P-type cladding layer 112, and a contact layer 113.

[0219] The N-type cladding layer 1104 is an N-type nitride semiconductor layer containing Al and arranged on the substrate 101. In this embodiment, the N-type cladding layer 1104 is doped with an average concentration of 1.0×10 18 cm -3 The Si film thickness is 1500nm N-type Al 0.065 Ga 0.935 N layers.

[0220] The active layer 1107 is a nitride-based semiconductor layer including a well layer 107b and barrier layers 107a and 1107c containing Al, and is disposed above the N-side optical guiding layer 106. The well layer 107b is disposed between the barrier layer 107a and the barrier layer 1107c.

[0221] The barrier layer 1107c is a nitride-based semiconductor layer that is disposed above the N-side optical guiding layer 106 and functions as a barrier of the quantum well structure. The barrier layer 1107c is disposed above the barrier layer 107a. In this embodiment, the average band gap energy of the barrier layer 1107c is greater than the average band gap energy of the well layer 107b. In this embodiment, the barrier layer 1107c is an undoped Al layer with a thickness of 10 nm. 0.04 Ga 0.96 N layers.

[0222] The lower P-side optical guiding layer 1111a is a nitride-based semiconductor layer containing Al arranged between the active layer 1107 and the electron blocking layer 109. In the present embodiment, the lower P-side optical guiding layer 1111a is arranged below the lower P-side intermediate layer 1110a. The lower P-side optical guiding layer 1111a has a larger average refractive index and a smaller average band gap energy than the P-type cladding layer 112. Furthermore, the average band gap energy of the lower P-side optical guiding layer 1111a is smaller than the average band gap energy of the P-type intermediate layer 1110 and the average band gap energy of the barrier layer 1107c, which is the topmost (i.e., the closest to the electron blocking layer 109) among the multiple barrier layers arranged in the active layer 1107. Accordingly, electrical conduction of holes (electron holes) from the P-type cladding layer 112 across the electron blocking layer 109 to the active layer 1107 becomes easy. Therefore, the operating voltage of the nitride-based semiconductor light-emitting element 1100 can be reduced.

[0223] In this embodiment, the average band gap energy of the lower P-side optical guiding layer 1111a is smaller than the average band gap energy of the lower P-side intermediate layer 1110a. As the lower P-side optical guiding layer 1111a, for example, an AlGaN layer or an AlGaInN layer can be used. The detailed configuration example of the lower P-side optical guiding layer 1111a will be described later.

[0224] The lower P-side intermediate layer 1110a is a nitride-based semiconductor layer containing Al disposed between the lower P-side optical guiding layer 1111a and the electron blocking layer 109. The average band gap energy of the lower P-side intermediate layer 1110a is larger than the average band gap energy of the lower P-side optical guiding layer 1111a and smaller than the average band gap energy of the electron blocking layer 109. The lower P-side intermediate layer 1110a can be doped with an average concentration of 2.0×10 18 cm -3The following P-type impurities are contained (the lower P-side intermediate layer 1110a may also be undoped). Furthermore, the average concentration of the P-type impurities in the lower P-side intermediate layer 1110a may also be lower than the average concentration of the P-type impurities in the P-type intermediate layer 1110. Thus, by making the average concentration of the P-type impurities in the lower P-side intermediate layer 1110a between 2.0×10 18 cm -3 In this embodiment, the lower P-side intermediate layer 1110a is 3 nm thick Al 0.04 Ga 0.96 The N layer can achieve both reduction of free carrier loss and suppression of voltage increase by making the N layer thinner and undoped.

[0225] The P-type intermediate layer 1110 is a P-type nitride semiconductor layer containing Al and arranged above the electron blocking layer 109. In this embodiment, the P-type intermediate layer 1110 is doped with an average concentration of 1.0×10 19 cm -3 The film thickness of Mg is 56nm P-type Al 0.05 Ga 0.95 N layer. In this embodiment, the lower end of the ridge 21R is located in the P-type intermediate layer 1110, and the distance dc between the lower end of the ridge 21R and the electron blocking layer 109 is 55nm. In addition, the lower end of the ridge 21R may also be located in the P-side optical guide layer 111 above the P-type intermediate layer 1110. For example, the distance dc between the lower end of the ridge 21R and the electron blocking layer 109 may be 58nm.

[0226] [11-2. Operation characteristics of configuration example 1]

[0227] The operating characteristics of the configuration example 1 of the nitride-based semiconductor light-emitting device 1100 according to the present embodiment are described. In the configuration example 1 of the nitride-based semiconductor light-emitting device 1100 according to the present embodiment, the lower P-side light-guiding layer 1111a is an AlGaN layer. Figure 20 to Figure 25 The operating characteristics of Configuration Example 1 of the nitride-based semiconductor light-emitting element 1100 will be described. Fig. 20 It is a line graph showing the relationship between the waveguide loss of Configuration Example 1 of the nitride-based semiconductor light-emitting element 1100 involved in the present embodiment and the Al composition ratio of the lower P-side optical guiding layer 1111a. Fig.21 It is a line graph showing the relationship between the operating current when the power consumption is 0.5 W and the Al composition ratio of the lower P-side light guiding layer 1111 a in the configuration example 1 of the nitride-based semiconductor light-emitting element 1100 involved in the present embodiment. Fig. 22It is a line graph showing the relationship between the operating voltage value when the power consumption is 0.5 W and the Al composition ratio of the lower P-side optical guiding layer 1111a in the configuration example 1 of the nitride-based semiconductor light-emitting element 1100 involved in this embodiment. Fig.23 It is a line graph showing the relationship between the optical confinement factor of Configuration Example 1 of the nitride-based semiconductor light-emitting element 1100 involved in this embodiment and the Al composition ratio of the lower P-side optical guiding layer 1111a. Fig.24 It is a line graph showing the relationship between the effective refractive index difference ΔN and the Al composition ratio of the lower P-side light guiding layer 1111 a in the configuration example 1 of the nitride-based semiconductor light-emitting element 1100 according to the present embodiment. Fig.25 This is a line graph showing the relationship between the WPE (Wall-Plug Efficiency) and the Al composition ratio of the lower P-side light guiding layer 1111a when the power consumption is 0.5 W in the configuration example 1 of the nitride-based semiconductor light emitting element 1100 according to the present embodiment. Figure 20 to Figure 25 Graph 3 shows the relationship when the film thickness T1 of the lower P-side light guiding layer 1111a is 9 nm, 20 nm, 40 nm, and 60 nm.

[0228] from Figure 21 to Figure 25 It can be seen that as the Al composition ratio of the lower P-side optical guiding layer 1111a as the AlGaN layer decreases, the operating voltage and the operating current decrease, and the optical confinement factor, the effective refractive index difference ΔN, and the WPE increase. Figure 21 to Figure 25 The Al composition ratio of the lower P-side light guiding layer 1111a can be set to 4% or less.

[0229] from Figure 21 to Figure 23 as well as Fig.25 It can be seen that as the film thickness T1 of the lower P-side optical guide layer 1111a increases, the operating voltage and operating current decrease, and the optical confinement factor and WPE increase. Figure 21 to Figure 23 as well as Fig.25 The film thickness T1 of the lower P-side light guide layer 1111a can be set to be greater than 9 nm. Fig.24 It can be seen that when the Al component ratio of the lower P-side optical guide layer 1111a is greater than 1%, the effective refractive index difference ΔN decreases with the increase of the film thickness T1, and the effective refractive index difference ΔN decreases with the increase of the Al component ratio of the lower P-side optical guide layer 1111a. Fig.24 , in order to obtain approximately 10×10 -3 With an effective refractive index difference ΔN of the above, the film thickness T1 of the lower P-side light guiding layer 1111a can be set to be less than 60 nm.

[0230] If you refer to Fig. 20, the waveguide loss is almost independent of the Al composition ratio of the lower P-side optical guiding layer 1111a. Therefore, in order to reduce the occurrence of light absorption loss in the lower P-side optical guiding layer 1111a, the Al composition ratio of the lower P-side optical guiding layer 1111a can be made greater than 0. Accordingly, since the band gap energy of the lower P-side optical guiding layer 1111a can be made larger than the band gap energy of GaN, the light absorption loss of the lower P-side optical guiding layer 1111a can be reduced. Furthermore, in order to further reduce the light absorption loss of the lower P-side optical guiding layer 1111a, the Al composition ratio of the lower P-side optical guiding layer 1111a can be made greater than 1%.

[0231] From the viewpoint of increasing the refractive index and improving the electrical conductivity of the lower P-side optical guiding layer 1111a, the band gap energy of the lower P-side optical guiding layer 1111a may be lower than the band gap energy of the adjacent barrier layer 1107c. 0.04 Ga 0.96 For the N layer, if the band gap energy of the lower P-side optical guiding layer 1111a is to be lower than the band gap energy of the barrier layer 1107c, the Al composition ratio of the lower P-side optical guiding layer 1111a can be lower than 4%.

[0232] The Al composition ratio of the lower P-side light guiding layer 1111a may also be lower than the Al composition ratio of the P-side light guiding layer 111. For example, in the present embodiment, since the Al composition ratio of the P-side light guiding layer 111 is 3%, the Al composition ratio of the lower P-side light guiding layer 1111a may be lower than 3%. Accordingly, since the refractive index of the lower P-side light guiding layer 1111a can be made higher than the refractive index of the P-side light guiding layer 111, the operating voltage and the operating current can be reduced, and the optical confinement factor, the effective refractive index difference ΔN, and the WPE can be increased.

[0233] The lower P-side optical guiding layer 1111a may be an undoped AlGaN layer, thereby suppressing light absorption due to the increase in impurity concentration described above.

[0234] use Fig.26 An example of configuration example 1 of the nitride-based semiconductor light-emitting element 1100 according to the present embodiment will be described. Fig.26 The structures and characteristics of Examples 1 to 4 of the nitride-based semiconductor light-emitting element 1100 according to this embodiment are shown. Fig.26 The structure and characteristics of the nitride-based semiconductor light-emitting element involved in Comparative Example 2 are also shown. The nitride-based semiconductor light-emitting element involved in Comparative Example 2 is different from the nitride-based semiconductor light-emitting element 1100 involved in this embodiment in that it does not have a lower P-side light-guiding layer 1111a, and the other parts are the same.

[0235] like Fig.26 As shown, in Example 1, the Al component ratio of the lower P-side light guiding layer 1111a is 1.0%, and the film thickness T1 is 9.0nm, in Example 2, the Al component ratio of the lower P-side light guiding layer 1111a is 2.0%, and the film thickness T1 is 20.0nm, in Example 3, the Al component ratio of the lower P-side light guiding layer 1111a is 3.0%, and the film thickness T1 is 40.0nm, and in Example 4, the Al component ratio of the lower P-side light guiding layer 1111a is 1.0%, and the film thickness T1 is 60.0nm.

[0236] like Fig.26 As shown, in Examples 1 to 4, compared with Comparative Example 2 which does not have the lower P-side optical guide layer 1111a, the operating voltage and operating current are reduced and the optical confinement factor and WPE are increased. In addition, in Examples 1 to 4, 10×10 -3 In this way, in Examples 1 to 4, by providing the lower P-side light guiding layer 1111a, it is possible to achieve 10×10 -3 The above effective refractive index difference ΔN can reduce the operating voltage and the operating current, and can also increase the optical confinement factor and WPE.

[0237] [11-3. Operation characteristics of configuration example 2]

[0238] The operating characteristics of the second configuration example of the nitride-based semiconductor light-emitting device 1100 according to the present embodiment will be described. In the second configuration example of the nitride-based semiconductor light-emitting device 1100 according to the present embodiment, the lower P-side light-guiding layer 1111a is an AlGaInN layer. Figures 27 to 32 The operating characteristics of Configuration Example 2 of the nitride-based semiconductor light-emitting element 1100 are described. Fig. 27 It is a line graph showing the relationship between the waveguide loss of Configuration Example 2 of the nitride-based semiconductor light-emitting element 1100 involved in the present embodiment and the In composition ratio of the lower P-side optical guiding layer 1111a. Fig.28 It is a line graph showing the relationship between the operating current and the In composition ratio of the lower P-side optical guiding layer 1111a when the power consumption is 0.5 W in the configuration example 2 of the nitride-based semiconductor light-emitting element 1100 involved in this embodiment. Fig.29 It is a line graph showing the relationship between the operating voltage value when the power consumption is 0.5 W and the In composition ratio of the lower P-side optical guiding layer 1111a in the configuration example 2 of the nitride-based semiconductor light-emitting element 1100 involved in this embodiment. Fig.30 It is a line graph showing the relationship between the optical confinement factor of Configuration Example 2 of the nitride-based semiconductor light-emitting element 1100 involved in this embodiment and the In composition ratio of the lower P-side optical guiding layer 1111a. Fig.31 It is a line graph showing the relationship between the effective refractive index difference ΔN and the In composition ratio of the lower P-side light guiding layer 1111 a in Configuration Example 2 of the nitride-based semiconductor light-emitting element 1100 according to the present embodiment. Fig.32 This is a line graph showing the relationship between the WPE and the In composition ratio of the lower P-side optical guide layer 1111a when the power consumption is 0.5 W in the configuration example 2 of the nitride-based semiconductor light-emitting element 1100 according to the present embodiment. Figures 27 to 32 2 shows the relationship when the film thickness T1 of the lower P-side light guiding layer 1111a is 9 nm, 20 nm, 40 nm, and 60 nm. In addition, the Al composition ratio of the lower P-side light guiding layer 1111a is 4.0% in all cases.

[0239] from Figure 28 to Figure 32 It can be seen that as the In composition ratio of the lower P-side optical guide layer 1111a as the AlGaInN layer increases, the operating voltage and operating current decrease, and the optical confinement factor, effective refractive index difference ΔN, and WPE increase. Figure 28 to Figure 32 The In composition ratio of the lower P-side light guiding layer 1111 a can be set to a value greater than 0%.

[0240] from Figures 28 to 30 as well as Fig.32 It can be seen that as the film thickness T1 of the lower P-side optical guide layer 1111a increases, the operating voltage and operating current decrease, and the optical confinement factor and WPE increase. Figures 28 to 30 as well as Fig.32 , the film thickness T1 of the lower P-side light guide layer 1111a can be set to be greater than 9nm. Fig.31 It can be seen that when the In component ratio of the lower P-side optical guide layer 1111a is greater than 1%, the effective refractive index difference ΔN decreases with the increase of the film thickness T1, and the effective refractive index difference ΔN increases with the increase of the In component ratio of the lower P-side optical guide layer 1111a. Fig.31 , in order to obtain approximately 10×10 -3 With an effective refractive index difference ΔN of the above, the film thickness T1 of the lower P-side light guiding layer 1111a can be set to be less than 60 nm.

[0241] If you refer to Fig. 27Since the waveguide loss is almost independent of the In composition ratio of the lower P-side optical guiding layer 1111a, in order to reduce the occurrence of light absorption loss in the lower P-side optical guiding layer 1111a, the composition of the lower P-side optical guiding layer 1111a can be set in such a way that the band gap energy of the lower P-side optical guiding layer 1111a is larger than the band gap energy of GaN. The Al composition ratio of the lower P-side optical guiding layer 1111a can be greater than 3% and less than 6%, and the In composition ratio can be greater than 0% and less than 2%. Within this range of the Al composition ratio and the In composition ratio of the lower P-side optical guiding layer 1111a, from the viewpoint of increasing the refractive index of the lower P-side optical guiding layer 1111a and improving the electrical conductivity, the Al composition ratio and the In composition ratio can be set in such a way that the band gap energy of the lower P-side optical guiding layer 1111a is less than the band gap energy of the adjacent barrier layer 1107c.

[0242] The band gap energy of the lower P-side optical guiding layer 1111a may be lower than the band gap energy of the P-side optical guiding layer 111. Accordingly, since the refractive index of the lower P-side optical guiding layer 1111a can be higher than the refractive index of the P-side optical guiding layer 111, the operating voltage and the operating current can be reduced and the optical confinement factor, the effective refractive index difference ΔN, and the WPE can be increased.

[0243] The lower P-side optical guiding layer 1111a may be an undoped AlGaInN layer, thereby suppressing light absorption due to the increase in impurity concentration described above.

[0244] By using an AlGaInN layer as the lower P-side light guiding layer 1111a, an AlGaInN layer as a deformation layer having compressibility with respect to the substrate 101 can be arranged below and near the ridge 21R. As a result, the shear stress in the lower end of the ridge 21R caused by the AlGaN layer as a deformation layer having tensile properties with respect to the substrate 101 can be reduced. In addition, the warping of the wafer as the base material used in manufacturing the nitride-based semiconductor light-emitting element 1100 can be suppressed, thereby suppressing the occurrence of wafer breakage in the process after the lamination of the lower P-side light guiding layer 1111a.

[0245] The Al composition ratio of the lower P-side light guiding layer 1111a can be equal to the Al composition ratio of the adjacent barrier layer 1107c. In this case, when the barrier layer 1107c and the lower P-side light guiding layer 1111a are continuously formed, in the formation process of the lower P-side light guiding layer 1111a, only the In composition ratio can be changed relative to the formation process of the barrier layer 1107c. Therefore, since the controllability of the atomic composition in the formation process of the lower P-side light guiding layer 1111a can be improved, the distribution of the components of the lower P-side light guiding layer 1111a in the plane (distribution in the plane perpendicular to the stacking direction) can be uniformized. Accordingly, when a plurality of nitride-based semiconductor light emitting elements 1100 are formed on a wafer, for example, the characteristics of each nitride-based semiconductor light emitting element 1100 can be uniformized. Furthermore, the In composition ratio of the lower P-side light guiding layer 1111a can be changed according to the position in the stacking direction. For example, the In composition ratio in the region close to the active layer 1107 in the lower P-side light guiding layer 1111a may be greater than the In composition ratio in the region far from the active layer 1107. As a result, since the band gap energy in the region close to the active layer 1107 of the lower P-side light guiding layer 1111a can be reduced, the conductivity of holes in the region can be improved. Therefore, the operating voltage of the nitride-based semiconductor light emitting element 1100 can be further reduced.

[0246] use Fig.33 An example of configuration example 2 of the nitride-based semiconductor light-emitting element 1100 according to the present embodiment will be described. Fig.33 The structures and characteristics of Examples 5 to 8 of the nitride-based semiconductor light-emitting element 1100 according to the present embodiment are shown. Fig.33 The structure and characteristics of the nitride-based semiconductor light-emitting element according to Comparative Example 2 are also shown.

[0247] like Fig.33 As shown, in Examples 5 to 8, the Al composition ratio of the lower P-side light guide layer 1111a is 4.0%, and the In composition ratio is 1.3%. In Example 5, the film thickness T1 is 9.0 nm, in Example 6, the film thickness T1 is 20.0 nm, in Example 7, the film thickness T1 is 40.0 nm, and in Example 8, the film thickness T1 is 60.0 nm.

[0248] like Fig.33 As shown, in Examples 5 to 8, compared with Comparative Example 2 without the lower P-side optical guide layer 1111a, the operating voltage and operating current are reduced, and the optical confinement factor and WPE are increased. In addition, in Examples 5 to 8, 10×10 -3 Thus, in Examples 5 to 8, by providing the lower P-side light guiding layer 1111a, it is possible to achieve 10×10-3 The above effective refractive index difference ΔN can reduce the operating voltage and the operating current, and can also increase the optical confinement factor and WPE.

[0249] (Variation examples, etc.)

[0250] The nitride-based semiconductor light-emitting device according to the present disclosure has been described above based on the various embodiments, but the present disclosure is not limited to the above-described embodiments.

[0251] For example, in each of the above-mentioned embodiments, although an example in which the nitride-based semiconductor light-emitting element is a semiconductor laser element is shown, the nitride-based semiconductor light-emitting element is not limited to the semiconductor laser element. For example, the nitride-based semiconductor light-emitting element may also be a superluminescent diode. In this case, the reflectivity of the end face of the semiconductor stack possessed by the nitride-based semiconductor light-emitting element for the light emitted from the semiconductor stack may be less than 0.1%. Such a reflectivity can be achieved, for example, by forming an anti-reflection film composed of a multilayer dielectric film or the like on the end face. Alternatively, if the ridge that becomes the waveguide is an inclined stripe structure that is inclined at more than 5° from the normal direction of the front end face to intersect with the front end face, the waveguide light reflected at the front end face can be combined with the waveguide again, and the proportion of the component that becomes the waveguide light can be set to a small value of less than 0.1%.

[0252] Furthermore, in Embodiments 1 to 5, although the impurity concentration in the P-type intermediate layer decreases as it is farther away from the electron blocking layer 109 , the impurity concentration in at least a portion of the P-type intermediate layer may increase as it is farther away from the electron blocking layer 109 .

[0253] Furthermore, although each of the nitride-based semiconductor light-emitting elements according to Embodiments 7 to 9 includes a P-type intermediate layer, it is not necessary to include a P-type intermediate layer.

[0254] Furthermore, although the P-type cladding layer 112 has a uniform Al composition ratio, the configuration of the P-type cladding layer 112 is not limited thereto. For example, the P-type cladding layer 112 may have a superlattice structure in which a plurality of AlGaN layers and a plurality of GaN layers are alternately stacked.

[0255] In the above-mentioned first embodiment, the P-side electrode 131 is described as including Ag. However, even in other embodiments, the P-side electrode 131 may include Ag. Accordingly, in other embodiments, the same effect as that achieved by the P-side electrode 131 including Ag in the first embodiment can be achieved.

[0256] Furthermore, the present disclosure includes methods of implementing various modifications that can be conceived by those skilled in the art for the above-mentioned embodiments, and methods of realizing the above-mentioned embodiments by arbitrarily combining the constituent elements and functions in the above-mentioned embodiments without departing from the gist of the present disclosure.

[0257] For example, each of the configurations according to Embodiments 2 to 6 may be combined with each of the configurations according to Embodiments 7 to 9.

[0258] Furthermore, the P-type inclined region according to the fourth embodiment may be included in the P-type intermediate layer according to other embodiments.

[0259] Furthermore, the N-type inclined region according to the ninth embodiment may be included in the N-type intermediate layer according to the seventh or eighth embodiment.

[0260] Industrial Applicability

[0261] The nitride-based semiconductor light-emitting device disclosed in the present invention can be suitably used as a light source with high output and high efficiency, for example, in exposure equipment and processing equipment.

[0262] Description of Reference Numerals

[0263] 10T component separation groove

[0264] 11R, 21R spine

[0265] 11Rs side

[0266] 11T, 21T slot

[0267] 100, 300, 700, 1100 nitride semiconductor light emitting elements

[0268] 100F, 100R end face

[0269] 100S, 700S, 1100S semiconductor stacks

[0270] 101 substrate

[0271] 102 base layer

[0272] 103 buffer layer

[0273] 104, 1104N type coating

[0274] 106, 706N side light guide layer

[0275] 107, 1107 active layer

[0276] 107a, 107c, 1107c barrier layer

[0277] 107b well layer

[0278] 109 electron blocking layer

[0279] 110, 210, 410, 510, 610, 1110P type intermediate layer

[0280] 111P side light guide layer

[0281] 112P type coating

[0282] 113 contact layer

[0283] 120 current blocking layer

[0284] 131P side electrode

[0285] 132 close-fitting layer

[0286] 133 pad electrode

[0287] 140N side electrode

[0288] 410a, 610a first P-type intermediate layer

[0289] 410b, 610b second P-type intermediate layer

[0290] 705, 805, 905, 1005N type middle layer

[0291] 805a, 1005a first N-type intermediate layer

[0292] 805b, 1005b second N-type intermediate layer

[0293] 1110a P-side intermediate layer below

[0294] 1111a P-side light guide layer below

Claims

1. A nitride-based semiconductor light-emitting device, which is a nitride-based semiconductor light-emitting device that emits light. The nitride-based semiconductor light-emitting device comprises: substrate; An N-type cladding layer disposed above the substrate and containing Al; an N-side light guiding layer disposed above the N-type cladding layer and containing Al; an active layer disposed above the N-side optical guiding layer and including one or more well layers and a plurality of barrier layers containing Al; an electron blocking layer disposed above the active layer and containing Al; A P-type intermediate layer disposed above the electron blocking layer and containing Al; A P-side light guiding layer disposed above the P-type intermediate layer and containing Al; as well as A P-type cladding layer including Al and arranged above the P-side light guiding layer, In the nitride-based semiconductor light-emitting device, The average band gap energy of the electron blocking layer is greater than the average band gap energy of the P-type cladding layer, The average band gap energy of the P-type intermediate layer is larger than the average band gap energy of the P-side optical guiding layer and smaller than the average band gap energy of the electron blocking layer. The average impurity concentration of the P-type intermediate layer is lower than the average impurity concentration of the electron blocking layer and higher than the average impurity concentration of the P-side optical guiding layer. The peak wavelength of the light is less than 400 nm.

2. The nitride-based semiconductor light-emitting device according to claim 1, The average band gap energy of the P-type intermediate layer is smaller than the average band gap energy of the P-type cladding layer.

3. The nitride-based semiconductor light-emitting device according to claim 1 or 2, The thickness of the P-type intermediate layer is greater than 10 nm.

4. The nitride-based semiconductor light-emitting device according to claim 3, The thickness of the P-type intermediate layer is greater than 20 nm.

5. The nitride-based semiconductor light-emitting device according to any one of claims 1 to 4, The P-type intermediate layer is an AlGaN layer, The average Al composition ratio of the P-type intermediate layer is greater than 3%.

6. The nitride-based semiconductor light-emitting device according to any one of claims 1 to 5, The average Al composition ratio of each of the N-type cladding layer, the N-side light guiding layer, the P-type intermediate layer, the P-side light guiding layer, and the P-type cladding layer is less than 10%.

7. The nitride-based semiconductor light-emitting device according to any one of claims 1 to 6, The P-type intermediate layer has: a first P-type intermediate layer; and A second P-type intermediate layer is disposed above the first P-type intermediate layer and has an average band gap energy smaller than that of the first P-type intermediate layer.

8. The nitride-based semiconductor light-emitting device according to claim 7, The average band gap energy of the first P-type intermediate layer is greater than the average band gap energy of the P-type cladding layer, The average band gap energy of the P-type intermediate layer is smaller than the average band gap energy of the P-type cladding layer.

9. The nitride-based semiconductor light-emitting device according to any one of claims 1 to 6, The P-type intermediate layer has: A first P-type intermediate layer having an average band gap energy smaller than that of the P-type cladding layer; and A second P-type intermediate layer is disposed above the first P-type intermediate layer and has an average band gap energy greater than that of the first P-type intermediate layer.

10. The nitride-based semiconductor light-emitting device according to any one of claims 1 to 9, The P-type intermediate layer has a P-type inclined region in which the Al composition ratio decreases as it moves away from the electron blocking layer. The average band gap energy of the P-type intermediate layer is smaller than the average band gap energy of the P-type cladding layer.

11. The nitride-based semiconductor light-emitting device according to any one of claims 1 to 10, The nitride-based semiconductor light-emitting element has a ridge extending in the propagation direction of the light. At least a portion of the P-type intermediate layer is disposed on the ridge portion.

12. The nitride-based semiconductor light-emitting device according to any one of claims 1 to 10, The nitride-based semiconductor light-emitting element has a ridge extending in the propagation direction of the light. The inclination angle of the side surface of the ridge portion with respect to the main surface of the substrate is greater than or equal to 60 degrees and less than 80 degrees.

13. The nitride-based semiconductor light-emitting device according to any one of claims 1 to 12, The nitride-based semiconductor light-emitting element includes a lower P-side light-guiding layer disposed between the active layer and the electron blocking layer and containing Al. The average band gap energy of the lower P-side optical guiding layer is smaller than the average band gap energy of the P-type intermediate layer and the average band gap energy of the barrier layer arranged at the top among the plurality of barrier layers.

14. The nitride-based semiconductor light-emitting device according to claim 13, The nitride-based semiconductor light-emitting element includes a lower P-side intermediate layer disposed between the lower P-side light-guiding layer and the electron blocking layer and containing Al. The average band gap energy of the lower P-side intermediate layer is larger than the average band gap energy of the lower P-side optical guiding layer, and smaller than the average band gap energy of the electron blocking layer.

15. The nitride-based semiconductor light-emitting device according to claim 13 or 14, The lower P-side light guiding layer is an AlGaN layer.

16. The nitride-based semiconductor light-emitting device according to claim 13 or 14, The lower P-side light guiding layer is an AlGaInN layer.

17. A nitride-based semiconductor light-emitting device, the nitride-based semiconductor light-emitting device emitting light. The nitride-based semiconductor light-emitting device comprises: substrate; An N-type cladding layer disposed above the substrate and containing Al; An N-type intermediate layer disposed above the N-type cladding layer and containing Al; an N-side light guiding layer disposed above the N-type intermediate layer and containing Al; An active layer disposed above the N-side optical guiding layer and including one or more well layers and a plurality of barrier layers containing Al; a P-side light guiding layer disposed above the active layer and containing Al; and A P-type cladding layer including Al and arranged above the P-side light guiding layer, In the nitride-based semiconductor light-emitting device, The average band gap energy of the N-type intermediate layer is larger than the average band gap energy of the N-side optical guiding layer and smaller than the average band gap energy of the N-type cladding layer. The average impurity concentration of the N-type intermediate layer is lower than the average impurity concentration of the N-type cladding layer and higher than the average impurity concentration of the N-side optical guide layer. The peak wavelength of the light is less than 400 nm.

18. The nitride-based semiconductor light-emitting device according to claim 17, The thickness of the N-type intermediate layer is greater than 20 nm.

19. The nitride-based semiconductor light-emitting device according to claim 17 or 18, The N-type intermediate layer is an AlGaN layer, The average Al composition ratio of the N-type intermediate layer is greater than 3%.

20. The nitride-based semiconductor light-emitting device according to any one of claims 17 to 19, The average Al composition ratio of each of the N-type cladding layer, the N-side light guiding layer, the N-type intermediate layer, the P-side light guiding layer, and the P-type cladding layer is less than 10%.

21. The nitride-based semiconductor light-emitting device according to any one of claims 17 to 20, The N-type intermediate layer has: a first N-type intermediate layer; and A second N-type intermediate layer is disposed above the first N-type intermediate layer and has an average band gap energy smaller than that of the first N-type intermediate layer.

22. The nitride-based semiconductor light-emitting device according to any one of claims 17 to 21, The N-type intermediate layer has an N-type inclined region in which the Al composition ratio increases as the distance from the N-side optical guiding layer increases.

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