LIGHT-EMISSIVING ELEMENT OF THE NITRIDE SEMICONDUCTOR TYPE

Abstract

A light-emitting element of the nitride semiconductor type contains: a first n-type semiconductor layer; a first p-type semiconductor layer arranged above and in contact with the first n-type semiconductor layer; a first superlattice layer arranged above the first p-type semiconductor layer and containing a p-type impurity; an active layer arranged above the first superlattice layer; a second n-type semiconductor layer arranged above the active layer; a first electrode electrically connected to the first n-type semiconductor layer; and a second electrode electrically connected to the second n-type semiconductor layer.

Description

CROSS-REFERENCE TO RELATED APPLICATIONS

[0001] This application claims priority to Japanese Patent Application No. 2023-165225, filed on September 27, 2023, and Japanese Patent Application No. 2024-087669, filed on May 30, 2024, the disclosures of which are hereby incorporated by reference in their entirety. BACKGROUND

[0002] The present disclosure relates to a nitride semiconductor type light-emitting element.

[0003] Nitride semiconductor type light-emitting elements need to be improved in luminous efficiency as their use expands, and the light-emitting element disclosed in Patent Publication No. 2020-501345 is described as being driven at a low current. OVERVIEW

[0004] However, as the application of nitride semiconductor type light-emitting elements is expanded, it is required to further drive the nitride semiconductor type light-emitting element with a low current and reduce a forward voltage.

[0005] Accordingly, it is an object of certain embodiments of the present disclosure to provide a nitride semiconductor type light-emitting element capable of operating at a low current and reducing a forward voltage.

[0006] According to one embodiment, a nitride semiconductor type light-emitting element includes: a first n-type semiconductor layer; a first p-type semiconductor layer disposed above the first n-type semiconductor layer and in contact with the first n-type semiconductor layer; a first superlattice layer disposed above the first p-type semiconductor layer and containing a p-type impurity; an active layer disposed above the first superlattice layer; a second n-type semiconductor layer disposed above the active layer; a first electrode electrically connected to the first n-type semiconductor layer; and a second electrode electrically connected to the second n-type semiconductor layer.

[0007] With the nitride semiconductor type light-emitting element configured as described above according to the present disclosure, it is possible to provide a nitride semiconductor type light-emitting element capable of driving with a low current and reducing a forward voltage. SHORT DESCRIPTION OF DRAWINGS Fig. 1 is a sectional view of the nitride semiconductor type light-emitting element according to Embodiment 1; Fig. 2 is an enlarged sectional view showing the first superlattice layer 40 in Fig. 1 represents; Fig. 3 is a sectional view of the nitride semiconductor type light-emitting element of Embodiment 2; Fig. 4 is a sectional view of the nitride semiconductor type light-emitting element of Embodiment 3; Fig. 5 is an enlarged sectional view showing the second superlattice layer 90 in Fig. 4 represents; Fig. 6 is a sectional view of the nitride semiconductor type light-emitting element of Embodiment 4-1; and Fig. 7 is a sectional view of the nitride semiconductor type light-emitting element of Embodiment 4-2. DETAILED DESCRIPTION

[0008] Embodiments and examples for carrying out the present disclosure will be described below with reference to the drawings. The nitride semiconductor type light-emitting elements and the methods for manufacturing nitride semiconductor type light-emitting elements described below are intended to embody the technical ideas of the present invention, but the present invention is not limited to the described embodiments unless otherwise specified.

[0009] In the drawings, components having the same function may be designated by the same reference numerals. The present invention may be described by dividing it into embodiments or examples for a better understanding of the essential points, but partial replacement or combination of the configurations described in different embodiments or examples is possible. In the following embodiments and examples, descriptions of things common to those described in the preceding embodiments or examples will be omitted, and only differences from the preceding embodiments or examples will be described. In particular, the same operations and effects achieved by the same configuration need not be repeated for each embodiment or example.The sizes, positional relationships, and the like of the components shown in the drawings may be exaggerated for the sake of clarity of description.

[0010] As in Fig. 1 and the like, the nitride semiconductor type light-emitting elements of the embodiments according to the present disclosure include: a first n-type semiconductor layer 20; a first p-type semiconductor layer 30 disposed above the first n-type semiconductor layer 20 and in contact with the first n-type semiconductor layer 20; a first superlattice layer 40 disposed above the first p-type semiconductor layer 30 and containing a p-type impurity; a first active layer 50 disposed above the first superlattice layer 40; a second n-type semiconductor layer 60 disposed above the first active layer 50; a first electrode 11 electrically connected to the first n-type semiconductor layer 20; and a second electrode 12 electrically connected to the second n-type semiconductor layer 60.

[0011] The nitride semiconductor type light-emitting elements of the embodiment according to the present disclosure configured as described above include the first superlattice layer 40 containing the p-type impurity between the first p-type semiconductor layer 30 and the first active layer 50. With this structure, the forward voltage Vf can be lowered and the light emission intensity can be increased with respect to the applied voltage.

[0012] The nitride semiconductor in the present specification refers to any binary to quaternary semiconductor containing nitrogen (N) and at least one of aluminum (Al), gallium (Ga) or indium (In), and may include semiconductors of all compositions in which the composition ratios x and y are within the respective ranges of the chemical formula of In x Al y Ga 1-x-y N (0 ≤ x ≤ 1, 0 ≤ y ≤ 1, x + y ≤ 1) can be varied.

[0013] In the following description, nitride semiconductor type light-emitting elements according to certain embodiments of the present disclosure are described in detail. Embodiment 1

[0014] Fig. 1 is a sectional view of the nitride semiconductor type light-emitting element of Embodiment 1. Fig. Fig. 2 is a sectional view of the first superlattice layer 40 in the nitride semiconductor type light-emitting element of the Fig. 1.

[0015] As in Fig. 1, the semiconductor light-emitting element of Embodiment 1 includes, for example, a substrate 10 and a first light-emitting part 1 disposed above the substrate 10. The first light-emitting part 1 includes a first n-type semiconductor layer 20 disposed above the substrate 10, a first p-type semiconductor layer 30 disposed above the first n-type semiconductor layer 20, a first superlattice layer 40 disposed above the first p-type semiconductor layer 30 and containing a p-type impurity, a first active layer 50 disposed above the first superlattice layer 40, and a second n-type semiconductor layer 60 disposed above the first active layer 50. Each of the first n-type semiconductor layer 20, the first p-type semiconductor layer 30, the first superlattice layer 40, the first active layer 50, and the second n-type semiconductor layer is formed of a nitride semiconductor.

[0016] Furthermore, the nitride semiconductor type light-emitting element of Embodiment 1 includes a first electrode 11 electrically connected to the first n-type semiconductor layer 20, for example, through ohmic contact with the first n-type semiconductor layer 20, and a second electrode 12 electrically connected to the second n-type semiconductor layer 60, for example, through ohmic contact with the second n-type semiconductor layer 60.

[0017] In the nitride semiconductor type light-emitting element of Embodiment 1 configured as described above, the first n-type semiconductor layer 20 and the first p-type semiconductor layer 30 are in contact with each other, and the current introduced from the first electrode 11 is introduced into the first active layer 50 via the first n-type semiconductor layer 20 and the first p-type semiconductor layer 30, and the first light-emitting part 1 emits light. That is, in the nitride semiconductor type light-emitting element of Embodiment 1, the first electrode 11 disposed on the first n-type semiconductor layer 20 is a positive electrode, and the second electrode 12 is a negative electrode.

[0018] In the nitride semiconductor type light-emitting element of Embodiment 1 according to the present disclosure, the first superlattice layer 40 containing the p-type impurity is arranged between the first p-type semiconductor layer 30 containing the p-type impurity and the first active layer 50 such that the forward voltage Vf is lowered and the light emission intensity is increased with respect to the applied voltage.

[0019] That is, the invention of the nitride semiconductor type light-emitting element according to Embodiment 1 of the present disclosure was made based on the knowledge clearly obtained by the present inventor that, in a light-emitting element configured such that a current injected from the positive electrode electrically connected to the first n-type semiconductor layer 20 is injected into the first active layer 50 via the first n-type semiconductor layer 20 and the first p-type semiconductor layer 30, disposing the first superlattice layer 40 containing the p-type impurity between the first p-type semiconductor layer 30 containing the p-type impurity and having p-type conductivity and the first active layer 50 makes it possible to increase the efficiency of supplying holes to the first active layer 50, lower the forward voltage Vf, and increase the light emission intensity with respect to the applied voltage.

[0020] Hereinafter, specific examples and preferred configurations of the first superlattice layer 40 will be described based on the findings obtained by the present inventor. <Erste Übergitterschicht>

[0021] Fig. 2 is an enlarged sectional view illustrating the first superlattice layer 40 in the nitride semiconductor type light-emitting element of Embodiment 1.

[0022] As in Fig. As shown in Figure 2, the first superlattice layer 40 includes a first layer 41 and a second layer 42. The first layer 41 and the second layer 42 are alternately stacked. The lattice constant of the second layers 42 differs from the lattice constant of the first layers 41. With the first superlattice layer 40 disposed between the first p-type semiconductor layer 30 and the first active layer 50, it is possible to reduce the distortion of the crystals of the first active layer 50 due to the difference in lattice constant between the first p-type semiconductor layer 30 and the first active layer 50. Reducing the distortion of the crystals of the first active layer 50 allows the internal quantum efficiency of the first active layer 50 to be increased. As a result, the light output can be improved.

[0023] The compositions of the first layer 41 and the second layer 42 are preferably adjusted considering, for example, the composition or band gap of the first active layer 50, and are preferably adjusted considering the composition or band gap of a well layer in a case where the first active layer 50 has a quantum well structure. For example, when the well layer is composed of an InGaN layer, it is preferable that the first layer 41 and the second layer 42 be layers having a lower In composition ratio than that of the well layer.

[0024] In the first layer 41 and the second layer 42, the lattice constant of the first layer 41 is different from the lattice constant of the second layer 42, for example, due to a difference in the In composition ratio. At least one of the first layer 41 or the second layer 42 is a layer doped with a p-type impurity. When at least one of the first layer 41 or the second layer 42 is doped with the p-type impurity, the forward voltage Vf can be lowered as described above. The p-type impurity concentration of at least one of the first layer 41 and the second layer 42 is preferably 1 × 10 18 cm -3 or more and 3 × 10 19 cm -3or less. Furthermore, the p-type impurity concentration doped in at least one of the first layer 41 and the second layer 42 is preferably lower than the p-type impurity concentration of the first p-type semiconductor layer 30.

[0025] For example, the In composition ratio of the first layer 41 may be greater than the In composition ratio of the second layer 42.

[0026] In this case, making the p-type impurity concentration of the first layer 41 higher than the p-type impurity concentration of the second layer 42 facilitates the reduction of the forward voltage Vf. It is believed that this is because allowing a dense distribution of In in the vicinity of the upper surface of the first layer 41 can facilitate a reduction in the surface roughness of the upper surface of the first layer 41, and thus the crystallinity of the first superlattice layer 40 is less likely to be deteriorated even though the first layer 41 is doped with the p-type impurity.

[0027] When the In composition ratio of the first layer 41 is larger than the In composition ratio of the second layer 42 and the p-type impurity concentration of the first layer 41 is larger than the p-type impurity concentration of the second layer 42, the p-type impurity concentration of the first layer 41 is preferably 1 × 10 18 cm -3 or more and 3 × 10 19 cm -3 or less. By setting the p-type impurity concentration of the first layer 41 within such a range, deterioration in the crystallinity of the first superlattice layer 40 can be reduced while increasing the efficiency of providing holes to the first active layer 50. In this case, the second layer 42 is preferably an undoped layer.

[0028] When the In composition ratio of the first layer 41 is greater than the In composition ratio of the second layer 42 and the p-type impurity concentration of the first layer 41 is greater than the p-type impurity concentration of the second layer 42, the thickness of the first layer 41 is preferably less than the thickness of the second layer 42. Reducing the thickness of the first layer 41, which has a relatively high p-type impurity concentration, makes it possible to prevent deterioration of the crystallinity of the first superlattice layer 40.

[0029] In particular, when the first n-type semiconductor layer 20 and the first p-type semiconductor layer 30 are connected by a tunnel junction, as described later, the impurity concentration in the junction region between the first n-type semiconductor layer 20 and the first p-type semiconductor layer 30 increases. However, with the first superlattice layer 40, diffusion of impurities into the first active layer 50 can be reduced, so that deterioration of the luminous efficiency due to the diffusion of the impurities into the first active layer 50 can be effectively reduced.

[0030] In the nitride semiconductor type light-emitting element of Embodiment 1 including the first superlattice layer 40 configured as described above, disposing the first superlattice layer 40 containing the p-type impurity between the first p-type semiconductor layer 30 containing the p-type impurity and having a p-type conductivity and the first active layer 50 enables a reduction in the forward voltage Vf and an increase in the light emission intensity with respect to the applied voltage.

[0031] Next, each component of the nitride semiconductor type light-emitting element of Embodiment 1 will be described in detail. Substrat

[0032] The material of the substrate 10 is, for example, sapphire, Si, SiC, GaN or the like.

[0033] The substrate 10 may be a growth substrate for growing a nitride semiconductor layer. A buffer layer may be disposed between the substrate 10 and the first n-type semiconductor layer 20. The substrate 10 may be removed after a semiconductor layer, such as the first n-type semiconductor layer 20, has grown. First n-type semiconductor layer 20

[0034] The first n-type semiconductor layer 20 may be composed, for example, of a nitride semiconductor layer containing an n-type impurity such as silicon (Si) or germanium (Ge). For example, when the first active layer 50 is composed of a nitride semiconductor layer containing In, the nitride semiconductor constituting the first n-type semiconductor layer 20 is, for example, an n-type GaN layer and may contain In, Al, or the like. Furthermore, when the first active layer 50 is composed of a nitride semiconductor containing Al, the nitride semiconductor constituting the first n-type semiconductor layer 20 is, for example, an n-type AlGaN layer and may further contain In.

[0035] The first n-type semiconductor layer 20 may include one or more n-type nitride semiconductor layers, and for example, the first n-type semiconductor layer 20 preferably includes a nitride semiconductor layer containing Si as an n-type impurity at a relatively high concentration of 8 × 10 19 cm -3 or more and 8 × 10 20 cm -3 or less doped than a layer connected to the first p-type semiconductor layer 30 by a tunnel junction. The layer connected to the first p-type semiconductor layer 30 by a tunnel junction is made of n-type GaN doped with Si at a concentration of 8 × 10 19 cm -3 or more and 8 × 10 20 cm -3or less, which is a relatively high concentration, and has a thickness of, for example, 1 nm or more and 10 nm or less. The first n-type semiconductor layer 20 preferably includes a nitride semiconductor layer containing an n-type impurity in addition to the layer connected by a tunnel junction. The n-type impurity concentration of the nitride semiconductor layer containing a different n-type impurity than the layer connected by a tunnel junction is preferably, for example, 1 × 10 18 cm -3 or more and 1 × 10 19 cm -3 or less, and for example. The first n-type semiconductor layer 20 may be composed of an n-type GaN layer containing Si as an n-type impurity in an amount of 1 × 10 18 cm -3 or more and 1 × 10 19 cm -3or less. The first n-type semiconductor layer 20 may partially contain an undoped semiconductor layer. As used herein, the undoped semiconductor layer refers to a layer to which no n-type impurity or p-type impurity is intentionally added. The total thickness of the first n-type semiconductor layer 20 is, for example, 5 µm or more and 15 µm or less. <Erste p-Typ-Halbleiterschicht 30>

[0036] The first p-type semiconductor layer 30 may, for example, consist of a nitride semiconductor layer containing a p-type impurity such as magnesium (Mg) or zinc (Zn).

[0037] For example, when the first active layer 50 is made of a nitride semiconductor layer containing In, the nitride semiconductor forming the first p-type semiconductor layer 30 is, for example, a p-type GaN layer and may contain In, Al, or the like. Furthermore, when the first active layer 50 is made of a nitride semiconductor containing Al, the nitride semiconductor forming the first p-type semiconductor layer 30 may be, for example, a p-type AlGaN layer and may further contain In.

[0038] The first p-type semiconductor layer 30 may include one or more p-type nitride semiconductor layers. For example, the first p-type semiconductor layer 30 preferably includes a nitride semiconductor layer containing Mg as a p-type impurity at a concentration of 8 × 10 19 cm -3 or more and 8 × 10 20 cm -3or less, which is a relatively high concentration, than a layer connected by a tunnel junction to a layer included as the uppermost layer of the first n-type semiconductor layer 20. The layer connected by a tunnel junction in the first p-type semiconductor layer is made of p-type GaN doped with Mg at a concentration of 8 × 10 19 cm -3 or more and 8 × 10 20 cm -3or less, which is a relatively high concentration, and has a thickness of, for example, 1 nm or more and 30 nm or less. The first p-type semiconductor layer 30 preferably includes a nitride semiconductor layer containing a p-type impurity in addition to the layer connected by a tunnel junction, and the p-type impurity concentration of the nitride semiconductor layer containing a different p-type impurity than the layer connected by a tunnel junction is preferably, for example, 1 × 10 18 cm -3 or more and 1 × 10 19 cm -3 or less, and for example, the first p-type semiconductor layer 30 may be composed of a p-type GaN layer containing Mg as a p-type impurity in an amount of 1 × 10 18 cm -3 or more and 1 × 10 19 cm -3or less. The first p-type semiconductor layer 30 may partially contain an undoped semiconductor layer. The total thickness of the first p-type semiconductor layer 30 may be, for example, 0.04 µm or more and 0.2 µm or less. First active layer 50

[0039] The first active layer 50 is, for example, a nitride semiconductor layer that emits light having a peak emission wavelength of 200 nm or more and 760 nm or less. The first active layer 50 may, for example, have a multiple quantum well structure including a plurality of well layers and a plurality of barrier layers, or a single quantum well structure including a well layer and barrier layers disposed above both sides thereof. When the first active layer 50 has a single or multiple quantum well structure, the well layer is, for example, GaN, InGaN, or AlGaN, and the barrier layer is, for example, AlGaN or GaN. Second n-type semiconductor layer 60

[0040] The second n-type semiconductor layer 60 includes, for example, a nitride semiconductor layer containing an n-type impurity such as silicon (Si). The second n-type semiconductor layer 60 may include one or more n-type nitride semiconductor layers or may partially include an undoped semiconductor layer. For example, when the first active layer 50 is made of a nitride semiconductor layer containing In, the nitride semiconductor forming the second n-type semiconductor layer 60 is, for example, an n-type GaN layer and may include In, Al, or the like. For example, when the first active layer 50 is made of a nitride semiconductor containing Al, the nitride semiconductor forming the second n-type semiconductor layer 60 is, for example, an n-type AlGaN layer and may further include In.

[0041] The thickness of the second n-type semiconductor layer 60 may be, for example, 0.1 µm or more and 15 µm or less, preferably 0.1 µm or more and 5 µm or less, more preferably 0.1 µm or more and 3 µm or less, and particularly preferably 0.1 µm or more and 1 µm or less. When Si is included as the n-type impurity, the impurity concentration of the second n-type semiconductor layer 60 may be, for example, 1 × 10 18 cm -3 or more and 1 × 10 19 cm -3 or less. <Erste und zweite Elektroden>

[0042] The first electrode 11 and the second electrode 12 are electrodes electrically connected to the first n-type semiconductor layer 20 and the second n-type semiconductor layer 60, i.e., the n-type semiconductor layers, and may be made of, for example, a metal such as Au, Pt, Pd, Rh, Ni, W, Mo, Cr, Ti, Al, or Cu, or an alloy containing these metals. The first electrode 11 and the second electrode 12 may have a single layer structure or a stacked structure in which a plurality of layers are stacked. The first electrode 11 and the second electrode 12 may have, for example, a stacked structure in which a Ti layer, an Al-Si-Cu alloy layer, a Ti layer, a Pt layer, an Au layer, and a Ti layer are stacked in this order. Embodiment 2

[0043] Fig. 3 is a sectional view of the nitride semiconductor type light-emitting element of Embodiment 2.

[0044] As in Fig. As shown in Figure 3, the nitride semiconductor type light-emitting element of Embodiment 2 includes a second light-emitting part 2 on the first light-emitting part 1 of the nitride semiconductor type light-emitting element of Embodiment 1. The second light-emitting part 2 includes a second n-type semiconductor layer 60 shared with the first light-emitting part, a second active layer 70 disposed above the second n-type semiconductor layer 60, and a second p-type semiconductor layer 80 disposed above the second active layer 70. The nitride semiconductor type light-emitting element of Embodiment 2 includes a third electrode 13 electrically connected to the second p-type semiconductor layer 80. In the present example, the third electrode 13 may include a pad electrode 13a and an electrode layer 13b arranged in contact with the second p-type semiconductor layer 80.In the nitride semiconductor light-emitting element of Embodiment 2, the second electrode 12 is disposed above a portion of the second n-type semiconductor layer 60 exposed, for example, by removing a corresponding portion of the second active layer 70 and a corresponding portion of the second p-type semiconductor layer 80. The first electrode 11 is disposed above the first n-type semiconductor layer 20 in the same manner as in the nitride semiconductor light-emitting element of Embodiment 1.

[0045] In the nitride semiconductor type light-emitting element of Embodiment 2 configured as described above, the first electrode 11 functions as a positive electrode of the first light-emitting part 1. The third electrode 13 functions as a positive electrode of the second light-emitting part 2. The second electrode 12 functions as a negative electrode of the first light-emitting part 1 and the second light-emitting part 2.

[0046] In the nitride semiconductor type light-emitting element of Embodiment 2, the first light-emitting part 1 can be caused to emit light by applying a voltage between the first electrode 11 and the second electrode 12. In addition, the second light-emitting part 2 can be caused to emit light by applying a voltage between the third electrode 13 and the second electrode 12. As described above, the first light-emitting part 1 and the second light-emitting part 2 can be caused to emit light independently of each other.

[0047] Even if the first light-emitting part 1 and the second light-emitting part 2 are caused to emit light simultaneously, the light emission intensities of the first light-emitting part 1 and the second light-emitting part 2 can be individually controlled by adjusting the voltage applied between the first electrode 11 and the second electrode 12 and the voltage applied between the third electrode 13 and the second electrode 12.

[0048] Moreover, in the nitride semiconductor type light-emitting element of Embodiment 2, the first light-emitting part 1 has the same configuration as the nitride semiconductor type light-emitting element of Embodiment 1, such that the forward voltage Vf can be lowered to increase the light emission intensity with respect to the applied voltage.

[0049] In the nitride semiconductor type light-emitting element of Embodiment 2 configured as described above, the first light-emitting part 1 and the second light-emitting part 2 may have the same peak emission wavelength or different peak emission wavelengths. In other words, the peak emission wavelength of the first active layer 50 and the peak emission wavelength of the second active layer 70 may be the same or different. In the nitride semiconductor type light-emitting element of Embodiment 2, the second active layer 70 is located above the first active layer 50. With this structure, when the peak emission wavelength of the first active layer 50 is different from the peak emission wavelength of the second active layer 70, the color mixing performance can be improved.When the composition of the first active layer 50 differs from the composition of the second active layer 70, the peak emission wavelength of the first active layer 50 is different from the peak emission wavelength of the second active layer 70. For example, when the In composition ratio of the first active layer 50 differs from the In composition ratio of the second active layer 70, the peak emission wavelength of the first active layer 50 is different from the peak emission wavelength of the second active layer 70.

[0050] For example, in a nitride semiconductor type light-emitting element, luminous efficiency varies depending on the peak emission wavelength. As described above, in the nitride semiconductor type light-emitting element of Embodiment 2, even if the first light-emitting part 1 and the second light-emitting part 2 are simultaneously caused to emit light, the light emission intensities of the first light-emitting part 1 and the second light-emitting part 2 can be individually controlled by adjusting the voltage applied between the first electrode 11 and the second electrode 12 and the voltage applied between the third electrode 13 and the second electrode 12.Accordingly, in the nitride semiconductor type light-emitting element of Embodiment 2, even if the peak emission wavelength of the first active layer 50 is different from the peak emission wavelength of the second active layer 70, an appropriate emission color can be easily obtained by adjusting the voltage applied between the first electrode 11 and the second electrode 12 and the voltage applied between the third electrode 13 and the second electrode 12.

[0051] Hereinafter, each component of the nitride semiconductor type light-emitting element of Embodiment 2 will be described in detail. A description of the common components of Embodiment 1 will be omitted. Second active layer 70

[0052] The second active layer 70 is, for example, a nitride semiconductor layer that emits light having a peak emission wavelength of 200 nm or more and 760 nm or less. The second active layer 70 may, for example, have a multiple quantum well structure including a plurality of well layers and a plurality of barrier layers, or a single quantum well structure including a well layer and barrier layers disposed above both sides thereof. When the second active layer 70 has a single or multiple quantum well structure, the well layer is, for example, GaN, InGaN, or AlGaN, and the barrier layer is, for example, AlGaN or GaN. Second p-type semiconductor layer 80

[0053] The second p-type semiconductor layer 80 may be composed, for example, of a nitride semiconductor layer containing a p-type impurity such as Mg or Zn. For example, when the second active layer 70 is composed of a nitride semiconductor layer containing In, the nitride semiconductor constituting the second p-type semiconductor layer 80 is, for example, a p-type GaN layer and may contain In, Al, or the like. Further, for example, when the second active layer 70 is composed of a nitride semiconductor containing Al, the nitride semiconductor constituting the second p-type semiconductor layer 80 is, for example, a p-type AlGaN layer and may further contain In.

[0054] The second p-type semiconductor layer 80 may contain one or more p-type nitride semiconductor layers. The second p-type semiconductor layer 80 may partially contain an undoped semiconductor layer. The total thickness of the second p-type semiconductor layer 80 may be, for example, 0.04 µm or more and 0.2 µm or less. <Dritte Elektrode 13>

[0055] The third electrode 13 includes, for example, a pad electrode 13a and an electrode layer 13b arranged in contact with the second p-type semiconductor layer 80. For the electrode layer 13b, for example, a light-transmitting metal oxide such as ITO, ZnO, IZO, or In2O3, or a light-reflecting member such as silver can be used. When a light-transmitting member is used as the electrode layer 13b, light can be emitted from the second p-type semiconductor layer 80 side. The pad electrode 13a can be made of, for example, a metal such as Au, Pt, Pd, Rh, Ni, W, Mo, Cr, Ti, Al, or Cu, or an alloy containing these metals. Embodiment 3

[0056] Fig. 4 is a sectional view of the nitride semiconductor type light-emitting element of Embodiment 3.

[0057] As in Fig. 4, the nitride semiconductor type light-emitting element of Embodiment 3 is configured similarly to the nitride semiconductor type light-emitting element of Embodiment 2, except that it includes the second superlattice layer 90 provided between the second n-type semiconductor layer 60 and the second active layer 70 in the nitride semiconductor type light-emitting element of Embodiment 2.

[0058] That is, in the nitride semiconductor type light-emitting element of Embodiment 3, the second light-emitting part 2 includes the second superlattice layer 90.

[0059] Fig. Fig. 5 is an enlarged sectional view showing the second superlattice layer 90 of Fig. 4 represents.

[0060] The second superlattice layer 90 is described in detail below. Second superlattice layer 90

[0061] In the present embodiment, the second superlattice layer 90 includes a third layer 91 and a fourth layer 92 having a lattice constant different from that of the third layer 91. The second superlattice layer 90 is a layer in which the third layer 91 and the fourth layer 92 are alternately stacked. The third layer 91 and the fourth layer 92 differ, for example, in In composition ratio. With the second superlattice layer 90 disposed between the second n-type semiconductor layer 60 and the second active layer 70, the distortion of crystals of the second active layer 70 due to the difference between the lattice constant of the second n-type semiconductor layer 60 and the lattice constant of the second active layer 70 can be reduced. By reducing the distortion of the crystals of the second active layer 70, the internal quantum efficiency can be increased and the light output can be improved.Moreover, as described below, various effects can be obtained by appropriately selecting the impurity concentration, composition, thickness and the like of the third layer 91 and the fourth layer 92. Embodiment 3-1

[0062] In Embodiment 3-1, the third layer 91 and the fourth layer 92 are both undoped layers. Generally, in nitride semiconductors, as the number of layers having different compositions stacked on a growth substrate increases, the crystallinity on the upper layer side tends to deteriorate. Therefore, in the second superlattice layer 90 stacked on the first light-emitting part 1, where the third layer 91 and the fourth layer 92 are both undoped layers, deterioration of the crystallinity of the second superlattice layer 90 can be reduced. Embodiment 3-2

[0063] In Embodiment 3-2, at least one of the third layer 91 or the fourth layer 92 is a layer containing an n-type impurity. Examples of the n-type impurity include Si. The n-type impurity concentration of at least one of the third layer 91 or the fourth layer 92 is preferably 1 × 10 18 cm -3 or more and 1 × 10 19 cm -3 or less. With such a concentration, the efficiency of supplying electrons to the second active layer 70 can be improved, and the light output can be improved.

[0064] In Embodiment 3-2, the third layer 91 is preferably a layer containing an n-type impurity, and the third layer 91 is preferably a layer containing In, such as an InGaN layer. With such a structure, the deterioration of the crystallinity of the second superlattice layer 90 caused by the n-type impurity can be reduced, while the efficiency of supplying electrons to the second active layer 70 by the n-type impurity is improved.It is believed that the deterioration of the crystallinity of the second superlattice layer 90 due to the n-type impurity can be reduced because allowing a dense distribution of In in the vicinity of the upper surface of the third layer 91 allows the surface roughness of the upper surface of the third layer 91 to be reduced, and thus the crystallinity of the second superlattice layer 90 is less likely to deteriorate even though the n-type impurity is doped in the third layer 91.

[0065] In Embodiment 3-2, it is more preferable that the third layer 91 is a layer containing an n-type impurity and containing In, and that the fourth layer 92 is a layer having an n-type impurity concentration lower than that of the third layer 91 and an In composition ratio lower than that of the third layer 91. With this structure, the n-type impurity concentration of the second superlattice layer 90 can be increased, and the crystallinity of the second superlattice layer 90 is less likely to deteriorate. In this case, the fourth layer 92 may be a layer free of In.

[0066] The fourth layer 92 may be an undoped layer.

[0067] Further, in Embodiment 3-2, when the third layer 91 is a layer containing an n-type impurity and containing In, and the fourth layer 92 is a layer having an n-type impurity concentration lower than that of the third layer 91 and having an In composition ratio lower than that of the third layer 91, the thickness of the third layer 91 is preferably less than the thickness of the fourth layer 92. By reducing the thickness of the third layer 91 having a higher n-type impurity concentration than the fourth layer 92, deterioration of the crystallinity of the second superlattice layer 90 can be reduced. Embodiment 4

[0068] Each of Fig. 6 and Fig. 7 is a sectional view of a nitride semiconductor type light-emitting element of Embodiment 4.

[0069] Fig. 6 is a sectional view of the nitride semiconductor type light-emitting element of Embodiment 4-1, and Fig. Fig. 7 is a sectional view of the nitride semiconductor type light-emitting element of Embodiment 4-2. As shown in Fig. 6 and Fig. 7, in the nitride semiconductor type light-emitting element of Embodiment 4-1 and the nitride semiconductor type light-emitting element of Embodiment 4-2, the first n-type semiconductor layer 20 and the first p-type semiconductor layer 30 are similarly configured.

[0070] In particular, in the nitride semiconductor type light-emitting element of Embodiment 4-1 and the nitride semiconductor type light-emitting element of Embodiment 4-2, (a) the first n-type semiconductor layer 20 includes a third superlattice layer 22 and a first transition layer 21 disposed above the third superlattice layer 22 and in contact with the first p-type semiconductor layer 30, and (b) the first p-type semiconductor layer 30 includes a second junction layer 31 connected to the first junction layer 21 by a tunnel junction.

[0071] In addition, as in Fig. 6, the nitride semiconductor type light-emitting element of Embodiment 4-1 is configured similarly to the nitride semiconductor type light-emitting element of Embodiment 2, except for the first n-type semiconductor layer 20 and the first p-type semiconductor layer 30. As shown in Fig. 7, the nitride semiconductor type light-emitting element of Embodiment 4-2 is configured similarly to the nitride semiconductor type light-emitting element of Embodiment 3, except for the first n-type semiconductor layer 20 and the first p-type semiconductor layer 30.

[0072] The nitride semiconductor type light-emitting element of Embodiment 4 will be described in detail below.

[0073] In the following description, configurations common to the nitride semiconductor type light-emitting element of Embodiment 4-1 and the nitride semiconductor type light-emitting element of Embodiment 4-2 will be comprehensively explained, simply referring to “the nitride semiconductor type light-emitting element of Embodiment 4”.

[0074] As described above in Embodiment 1 and the like, it is preferable that the first n-type semiconductor layer 20 includes a layer connected to the first p-type semiconductor layer 30 by a tunnel junction, the first p-type semiconductor layer 30 includes a layer connected to the first n-type semiconductor layer 20 by a tunnel junction, and the first n-type semiconductor layer 20 and the first p-type semiconductor layer 30 are connected by a tunnel junction. In this configuration, when the first n-type semiconductor layer 20 and the first p-type semiconductor layer 30 are connected by a tunnel junction, it is preferable to reduce the forward voltage Vf.Accordingly, in the nitride semiconductor type light-emitting element of Embodiment 4, each of the first n-type semiconductor layer 20 and the first p-type semiconductor layer 30 includes a layer connected by a tunnel junction, and a superlattice layer is disposed above the side of the substrate 10 of the layer connected by a tunnel junction to the second p-type semiconductor layer in the first n-type semiconductor layer 20. .

[0075] That is, as explained above with reference to Fig. 6 and Fig. 7, in the nitride semiconductor type light-emitting element of Embodiment 4, (a) the first n-type semiconductor layer 20 includes the third superlattice layer 22 and the first junction layer 21 disposed above the third superlattice layer 22 and in contact with the first p-type semiconductor layer 30, and (b) the first p-type semiconductor layer 30 includes the second junction layer 31 connected to the first junction layer 21 through a tunnel junction.

[0076] In particular, as in Fig. 6 and Fig.As shown in Figure 7, in the nitride semiconductor light-emitting element of Embodiment 4, the first n-type semiconductor layer 20 includes, in order from the substrate 10 side, an n-type contact layer 23, a third superlattice layer 22, and a first junction layer 21. In the present example, the first junction layer 21 is located as the uppermost layer on the first p-type semiconductor layer 30 side in the first n-type semiconductor layer 20. In the nitride semiconductor light-emitting element of Embodiment 4, the first p-type semiconductor layer 30 includes, in order from the substrate 10 side, a second junction layer 31 and a third p-type semiconductor layer 32.In the present example, the second junction layer 31 is a layer located on the first n-type semiconductor layer 20 side in the first p-type semiconductor layer 30 and connected to the first junction layer 21 by a tunnel junction.

[0077] In the nitride semiconductor type light-emitting element of Embodiment 4 configured as described above, the first n-type semiconductor layer 20 and the first p-type semiconductor layer 30 are connected to each other by a tunnel junction, and the first n-type semiconductor layer 20 further includes the third superlattice layer 22. As a result, carriers generated in the layer to be connected by a tunnel junction can effectively contribute to light emission, and the forward voltage Vf can thereby be reduced.

[0078] In particular, it is considered that the forward voltage Vf may be reduced for the following reasons.

[0079] Preferably, the first junction layer 21 and the second junction layer 31, which are layers to be connected by a tunnel junction, are set to have a higher impurity concentration than that of the other layers, as described later.

[0080] Therefore, by using the first junction layer 21 and the second junction layer 31, both of which have a higher impurity concentration than those of the other layers, more carriers are generated than in the other layers, and the forward voltage Vf can be reduced.

[0081] However, the additional carriers generated due to the use of the first junction layer 21 and the second junction layer 31, both of which have a higher impurity concentration than those of the other layers, cannot effectively contribute to the light emission, and instead, the forward voltage Vf may increase.

[0082] The present inventors have suspected that defects present in the first transition layer 21 and the second transition layer 31 may prevent the large number of generated carriers from effectively contributing to light emission.

[0083] In particular, the inventors considered that the generated carriers are trapped by the defects present in the first transition layer 21 and the second transition layer 31 and thus the carriers cannot be allowed to effectively contribute to the light emission.

[0084] Accordingly, when the third superlattice layer 22 was disposed in the first n-type semiconductor layer 20 to reduce the defects generated in the first junction layer 21 and the second junction layer 31, the forward voltage Vf could be lowered, and the invention relating to the nitride semiconductor type light-emitting element of Embodiment 4 was made.

[0085] Next, the configurations of the first n-type semiconductor layer 20 and the first p-type semiconductor layer 30 in the nitride semiconductor type light-emitting element of Embodiment 4 will be described in detail. First n-type semiconductor layer 20

[0086] In the nitride semiconductor type light-emitting element of Embodiment 4, the first n-type semiconductor layer 20 includes, in order from the substrate 10 side, the n-type contact layer 23, the third superlattice layer 22, and the first junction layer 21 as described above. n-type contact layer 23

[0087] The n-type contact layer 23 is a layer on which the first electrode 11 is formed and may be made of, for example, a nitride semiconductor layer containing an n-type impurity such as silicon (Si) or germanium (Ge). For example, when the first active layer 50 is made of a nitride semiconductor layer containing In, the nitride semiconductor forming the n-type contact layer 23 is, for example, an n-type GaN layer and may contain In, Al, or the like. For example, when the first active layer 50 is made of a nitride semiconductor containing Al, the nitride semiconductor forming the n-type contact layer 23 is, for example, an n-type AlGaN layer and may further contain In.

[0088] The n-type impurity concentration of the n-type contact layer 23 is preferably, for example, 1 × 10 18 cm -3 or more and 1 × 10 19 cm -3or less and can be formed, for example, from an n-type GaN layer containing Si as an n-type impurity in an amount of 1 × 10 18 cm -3 or more and 1 × 10 19 cm -3 or less. Third superlattice layer 22

[0089] The third superlattice layer 22 is a layer for reducing defects in the first junction layer 21 and the second junction layer 31, which are connected by a tunnel junction, and is arranged between the n-type contact layer 23 and the first junction layer 21.

[0090] The third superlattice layer 22 includes a fifth layer and a sixth layer. The fifth layer and the sixth layer are alternately stacked, and the lattice constant of the fifth layer differs from the lattice constant of the sixth layer. By disposing the third superlattice layer 22 between the n-type contact layer 23 and the first transition layer 21, lattice defects in the first transition layer 21 can be reduced compared to a case where the first transition layer 21 is arranged in contact with the n-type layer 23. The compositions of the fifth layer and the sixth layer can be adjusted, for example, by considering the compositions or band gaps of the n-type contact layer 23, the first transition layer 21, and the second transition layer 31.For example, if the n-type contact layer 23, the first transition layer 21, and the second transition layer 31 are each composed of a GaN layer, the fifth layer may be composed of a GaN layer, and the sixth layer may be composed of an InGaN layer. If the n-type contact layer 23, the first transition layer 21, and the second transition layer 31 are each composed of a GaN layer, both the fifth layer and the sixth layer may be constructed with an InGaN layer, and the In composition ratios of the fifth layer and the sixth layer may be different from each other.

[0091] The third superlattice layer 22 may contain an n-type impurity, and due to the fact that the third superlattice layer 22 contains an n-type impurity, it is possible to efficiently supply electrons from the n-type contact layer 23 to the first junction layer 21. When the third superlattice layer 22 contains an n-type impurity, either one or both of the fifth layer and the sixth layer may contain the n-type impurity. When the third superlattice layer 22 contains an n-type impurity, the n-type impurity concentration of the third superlattice layer 22 is preferably 1 × 10 19 cm -3or less. For example, in the nitride semiconductor element of Embodiment 4-2, the n-type impurity concentration of the third superlattice layer 22 is preferably lower than the n-type impurity concentration of the second superlattice layer. Here, the n-type impurity concentration of the third superlattice layer 22 refers to an average value of the n-type impurity concentration of the entire third superlattice layer 22.

[0092] The thickness of the third superlattice layer 22 is preferably thinner as long as a desired defect reduction effect can be obtained for the first junction layer 21 and the second junction layer 31, and for example, the thickness of the third superlattice layer 22 is preferably thinner than the thickness of the first superlattice layer 40. By reducing the thickness of the third superlattice layer 22, the carrier injection into the first p-type semiconductor layer 30 via the tunnel junction can be improved without being reduced.

[0093] That is, when the third superlattice layer 22 is arranged, there is a possibility that V-wells are formed from the superlattice layer, and even if V-wells are formed, it is possible to prevent a decrease in carrier injection into the first p-type semiconductor layer 30 due to the formation of the V-wells by thinning the third superlattice layer 22.

[0094] In particular, when the third superlattice layer 22 is arranged to be thick and V-shaped grooves are formed from the third superlattice layer 22, the influence of the V-shaped grooves formed in the third superlattice layer 22 increases, the flatness of the tunnel junction interface decreases, and it is difficult to efficiently obtain a tunneling effect. That is, to efficiently obtain the tunneling effect, a certain level or more of flatness is required at the tunnel junction interface. If the certain level or more of flatness at the tunnel junction interface is lost, the tunneling effect will deteriorate.Therefore, in order to effectively maintain the tunneling effect even when V-wells are formed from the third superlattice layer 22, it is necessary to suppress the influence of the V-wells so that a certain level or more of flatness can be secured at the tunnel junction interface, and for this purpose, it is preferable to reduce the thickness of the third superlattice layer 22.

[0095] For example, as described above, the thickness of the third superlattice layer 22 is preferably less than the thickness of the first superlattice layer 40. The thickness of the third superlattice layer 22 can be changed, for example, by adjusting the thickness of the fifth layer or the thickness of the sixth layer and by adjusting the number of pairs including the fifth layer and the sixth layer.

[0096] For example, a case will be described where the first superlattice layer 40 includes n pairs, each including the first layer 41 and the second layer 42, and the third superlattice layer 22 includes m pairs, each including the fifth layer and the sixth layer. Here, n and m are integers of 1 or more. For example, the thickness of the first layer 41 of the first superlattice layer 40 and the thickness of the fifth layer of the third superlattice layer 22 may be 1 nm or more and 3 nm or less. The thickness of the second layer 42 of the first superlattice layer 40 and the thickness of the sixth layer of the third superlattice layer 22 may be 0.5 nm or more and 1.5 nm or less. For example, the number n of pairs in the first superlattice layer 40 may be set to 16 or more and 60 or less, and the number m of pairs in the third superlattice layer 22 may be set to 3 or more and 15 or less.The thicknesses of the first superlattice layer 40 and the third superlattice layer 22 can be adjusted within the above-described ranges of thickness and number of pairs, and the thickness of the third superlattice layer 22 can be made smaller than the thickness of the first superlattice layer 40.

[0097] For example, the first layer 41 and the fifth layer are formed to have the same thickness, the second layer 42 and the sixth layer are formed to have the same thickness, and the number of pairs m in the third superlattice layer 22 is made smaller than the number of pairs n in the first superlattice layer 40. As a result, the thickness of the third superlattice layer 22 can be formed smaller than the thickness of the first superlattice layer 40.

[0098] For example, when the first layer 41 of the first superlattice layer 40 and the fifth layer of the third superlattice layer 22 are GaN layers, and the second layer 42 of the first superlattice layer 40 and the sixth layer of the third superlattice layer 22 are InGaN layers, the thicknesses of the first layer 41 and the fifth layer made of GaN layers are made larger than the thicknesses of the second layer 42 and the sixth layer. First transition layer 21

[0099] The first transition layer 21 is, for example, a nitride semiconductor layer containing an n-type impurity in a relatively high concentration of 8 × 10 19 cm -3 or more and 8 × 10 20 cm -3or less, and is a layer connected to the second junction layer 31 through a tunnel junction. The n-type impurity concentration of the first junction layer 21 is higher than the n-type impurity concentration of the n-type contact layer 23.

[0100] The thickness of the first transition layer 21 is, for example, 1 nm or more and 10 nm or less. The first transition layer 21 may contain In. Due to the fact that the first transition layer 21 contains In, the band gap of the first transition layer 21 can be reduced, and the tunneling effect can be easily obtained.

[0101] The first transition layer 21 may include two or more layers, for example, a GaN layer and an InGaN layer. For example, a GaN layer disposed above the n-type contact layer 23 side and having a thickness of 1 nm or more and 10 nm or less, and an InGaN layer having a thickness of, for example, 0.5 nm or more and 5 nm or less may be included. The In composition ratio of the InGaN layer is, for example, 1% or more and 6% or less. First p-type semiconductor layer 30

[0102] In the nitride semiconductor type light-emitting element of Embodiment 4, the first p-type semiconductor layer 30 includes, in order from the substrate 10 side, a second junction layer 31 and a third p-type semiconductor layer 32. Second transition layer 31

[0103] The second transition layer 31 is, for example, a nitride semiconductor layer coated with a p-type impurity in a relatively high concentration of 8 × 10 19 cm -3 or more and 8 × 10 20 cm -3 or less, and is a layer connected to the first junction layer 21 through a tunnel junction. The p-type impurity concentration of the second junction layer 31 is higher than the p-type impurity concentration of the third p-type semiconductor layer 32 described later.

[0104] The thickness of the second transition layer 31 may be, for example, 1 nm or more and 30 nm or less. The second transition layer 31 may include two or more layers, each containing a p-type impurity with a higher concentration than that of the third p-type semiconductor layer 32. The second transition layer 31 may, for example, be a p-type GaN layer impurified with Mg at a concentration of 8 × 1019 cm -3 or more and 8 × 10 20 cm -3 or less and having a thickness of 1 nm or more and 10 nm or less, and containing a p-type GaN layer doped with Mg at a concentration lower than that of the p-type GaN layer (but the concentration is within a concentration range of 8 × 10 19 cm -3 or more and 3 × 10 20 cm -3 or less) and a thickness of 10 nm or more and 20 nm or less. Third p-type semiconductor layer 32

[0105] The third p-type semiconductor layer 32 is a nitride semiconductor layer containing a p-type impurity and is disposed above the second junction layer 31. The p-type impurity concentration of the third p-type semiconductor layer 32 is preferably, for example, 1 × 10 18 cm -3 or more and 1 × 10 19 cm -3or less and can be formed, for example, from a p-type GaN layer containing Mg as a p-type impurity in an amount of 1 × 10 18 cm -3 or more and 1 × 10 19 cm -3 or less.

[0106] The nitride semiconductor type light-emitting elements according to the embodiments of the present disclosure include, for example, the following aspects. [Aspect 1]

[0107] Nitride semiconductor type light-emitting element comprising: a first n-type semiconductor layer; a first p-type semiconductor layer disposed above the first n-type semiconductor layer and in contact with the first n-type semiconductor layer; a first superlattice layer disposed above the first p-type semiconductor layer and containing a p-type impurity; an active layer disposed above the first superlattice layer; a second n-type semiconductor layer disposed above the active layer; a first electrode electrically connected to the first n-type semiconductor layer; and a second electrode electrically connected to the second n-type semiconductor layer. [Aspect 2]

[0108] The nitride semiconductor type light-emitting element according to aspect 1, wherein the first superlattice layer comprises a first layer and a second layer having a lattice constant different from that of the first layer, the first layer and the second layer being alternately stacked, and the first layer contains In and a p-type impurity. [Aspect 3]

[0109] The nitride semiconductor type light-emitting element according to aspect 2, wherein the second layer contains In and a p-type impurity; a p-type impurity concentration of the second layer is lower than a p-type impurity concentration of the first layer; and an in-composition ratio of the second layer is lower than an in-composition ratio of the first layer. [Aspect 4]

[0110] The nitride semiconductor type light-emitting element according to aspect 3, wherein the p-type impurity concentration of the first layer is lower than a p-type impurity concentration of the first p-type semiconductor layer. [Aspect 5]

[0111] The nitride semiconductor type light-emitting element according to any one of aspects 2 to 4, wherein the p-type impurity concentration of the first layer is 1 × 10 18 cm -3 or more and 3 × 10 19 cm -3 or less. [Aspect 6]

[0112] The nitride semiconductor type light-emitting element according to any one of aspects 2 to 5, wherein a thickness of the first layer is less than a thickness of the second layer. [Aspect 7]

[0113] A nitride semiconductor type light-emitting element according to any one of aspects 1 to 6, further comprising: a second active layer disposed above the second n-type semiconductor layer; a second p-type semiconductor layer disposed above the second active layer; and a third electrode electrically connected to the second p-type semiconductor layer. [Aspect 8]

[0114] The nitride semiconductor type light-emitting element according to aspect 7, further comprising a second superlattice layer disposed between the second n-type semiconductor layer and the second active layer. [Aspect 9]

[0115] The nitride semiconductor type light-emitting element according to aspect 8, wherein the second superlattice layer comprises a third layer and a fourth layer having a lattice constant different from that of the third layer, the third layer and the fourth layer being alternately stacked; and the third layer and the fourth layer are undoped layers. [Aspect 10]

[0116] The nitride semiconductor type light-emitting element according to aspect 8 or 9, wherein the second superlattice layer comprises a third layer and a fourth layer having a lattice constant different from that of the third layer, the third layer and the fourth layer being alternately stacked; and the third layer contains an n-type impurity. [Aspect 11]

[0117] The nitride semiconductor type light-emitting element according to any one of aspects 8 to 10, wherein the third layer contains In. [Aspect 12]

[0118] The nitride semiconductor type light-emitting element according to aspect 11, wherein an n-type impurity concentration of the fourth layer is lower than an n-type impurity concentration of the third layer; and an in-composition ratio of the fourth layer is lower than an in-composition ratio of the third layer. [Aspect 13]

[0119] The nitride semiconductor type light-emitting element according to any one of aspects 9 to 12, wherein a thickness of the third layer is less than a thickness of the fourth layer. [Aspect 14]

[0120] The nitride semiconductor type light-emitting element according to any one of aspects 1 to 4, wherein the first n-type semiconductor layer comprises a third superlattice layer and a first transition layer disposed above the third superlattice layer and in contact with the first p-type semiconductor layer; and the first p-type semiconductor layer comprises a second junction layer connected to the first junction layer by a tunnel junction. [Aspect 15]

[0121] The nitride semiconductor type light-emitting element according to aspect 14, wherein a thickness of the third superlattice layer is less than a thickness of the first superlattice layer. [Aspect 16]

[0122] The nitride semiconductor type light-emitting element according to aspect 14 or 15, wherein the third superlattice layer contains an n-type impurity. [Aspect 17]

[0123] A nitride semiconductor type light-emitting element according to any one of aspects 14 to 16, further comprising: a second superlattice layer disposed above the second n-type semiconductor layer and containing an n-type impurity; a second active layer disposed above the second superlattice layer; a second p-type semiconductor layer disposed above the second active layer; and a third electrode electrically connected to the second p-type semiconductor layer, wherein an n-type impurity concentration of the third superlattice layer is lower than an n-type impurity concentration of the second superlattice layer. QUOTES CONTAINED IN THE DESCRIPTION

[0000] This list of documents submitted by the applicant was generated automatically and is included solely for the convenience of the reader. This list is not part of the German patent or utility model application. The DPMA assumes no liability for any errors or omissions. Cited patent literature

[0000] JP 2023-165225

[0001] JP 2024-087669

[0001]

Claims

[1] Nitride semiconductor type light-emitting element comprising: a first n-type semiconductor layer; a first p-type semiconductor layer disposed above and in contact with the first n-type semiconductor layer; a first superlattice layer disposed above the first p-type semiconductor layer and containing a p-type impurity; an active layer disposed above the first superlattice layer; a second n-type semiconductor layer disposed above the active layer; a first electrode electrically connected to the first n-type semiconductor layer; and a second electrode electrically connected to the second n-type semiconductor layer. [2] The nitride semiconductor type light-emitting element according to claim 1, wherein the first superlattice layer comprises a first layer containing In and a p-type impurity and a second layer having a lattice constant different from that of the first layer, the first layer and the second layer being alternately stacked. [3] A nitride semiconductor type light-emitting element according to claim 2, wherein: the second layer contains In and a p-type impurity; a p-type impurity concentration of the second layer is lower than a p-type impurity concentration of the first layer; and an in-composition ratio of the second layer is lower than an in-composition ratio of the first layer. [4] The nitride semiconductor type light-emitting element according to claim 3, wherein the p-type impurity concentration of the first layer is lower than a p-type impurity concentration of the first p-type semiconductor layer. [5] The nitride semiconductor type light-emitting element according to claim 2, wherein the p-type impurity concentration of the first layer is 1 × 10 18 cm -3 or more and 3 × 10 19 cm -3 or less. [6] The nitride semiconductor type light-emitting element according to claim 2, wherein a thickness of the first layer is less than a thickness of the second layer. [7] A nitride semiconductor type light-emitting element according to claim 1, further comprising: a second active layer disposed above the second n-type semiconductor layer; a second p-type semiconductor layer disposed above the second active layer; and a third electrode electrically connected to the second p-type semiconductor layer. [8] The nitride semiconductor type light-emitting element according to claim 7, further comprising a second superlattice layer disposed between the second n-type semiconductor layer and the second active layer. [9] A nitride semiconductor type light-emitting element according to claim 8, wherein: the second superlattice layer comprises a third layer and a fourth layer having a lattice constant different from that of the third layer, the third layer and the fourth layer being alternately stacked; and the third layer and the fourth layer are undoped layers. [10] A nitride semiconductor type light-emitting element according to claim 8, wherein: the second superlattice layer comprises a third layer and a fourth layer having a lattice constant different from that of the third layer, the third layer and the fourth layer being alternately stacked; and the third layer contains an n-type impurity. [11] The nitride semiconductor type light-emitting element according to claim 10, wherein the third layer contains In. [12] A nitride semiconductor type light-emitting element according to claim 11, wherein: an n-type impurity concentration of the fourth layer is lower than an n-type impurity concentration of the third layer; and an in-composition ratio of the fourth layer is lower than an in-composition ratio of the third layer. [13] The nitride semiconductor type light-emitting element according to claim 10, wherein a thickness of the third layer is less than a thickness of the fourth layer. [14] A nitride semiconductor type light-emitting element according to claim 1, wherein: the first n-type semiconductor layer comprises a third superlattice layer and a first transition layer disposed above the third superlattice layer and in contact with the first p-type semiconductor layer; and the first p-type semiconductor layer comprises a second junction layer connected to the first junction layer by a tunnel junction. [15] The nitride semiconductor type light-emitting element according to claim 14, wherein a thickness of the third superlattice layer is smaller than a thickness of the first superlattice layer. [16] The nitride semiconductor type light-emitting element according to claim 14, wherein the third superlattice layer contains an n-type impurity. [17] A nitride semiconductor type light-emitting element according to claim 16, further comprising: a second superlattice layer disposed above the second n-type semiconductor layer and containing an n-type impurity; a second active layer disposed above the second superlattice layer; a second p-type semiconductor layer disposed above the second active layer; and a third electrode electrically connected to the second p-type semiconductor layer, wherein an n-type impurity concentration of the third superlattice layer is lower than an n-type impurity concentration of the second superlattice layer.

Images