Nitride semiconductor light-emitting element

Abstract

Provided is a nitride semiconductor light-emitting element that can be driven at a low current and that can reduce a forward voltage. The semiconductor device includes: a first n-type semiconductor layer including an n-type impurity; a first p-type semiconductor layer disposed on the first n-type semiconductor layer and including a p-type impurity; an active layer disposed on the first p-type semiconductor layer and having a hole portion; an intermediate layer that is disposed on the active layer and is composed of a semiconductor that does not substantially contain an n-type impurity; a second n-type semiconductor layer disposed on the intermediate layer and containing an n-type impurity; 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, and an intermediate layer covering at least the inner surface of the hole.

Description

Technical Field

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

[0002] As the applications of nitride semiconductor light-emitting elements expand, there is a demand for improved light-emitting efficiency. The light-emitting element disclosed in Patent Document 1 can be driven at a low current.

[0003] Prior art literature

[0004] Patent Literature

[0005] Patent Document 1: (Japan) Japanese Patent Publication No. 2020-501345 Summary of the Invention

[0006] Technical problem to be solved by the invention

[0007] However, nitride semiconductor light-emitting elements are required to be driven at a low current and to reduce the forward voltage.

[0008] Therefore, an object of the present disclosure is to provide a nitride semiconductor light-emitting element that can be driven at a low current and has a reduced forward voltage.

[0009] Technical solutions to technical problems

[0010] To achieve the above objectives, the semiconductor light-emitting element disclosed herein includes: a first n-type semiconductor layer containing n-type impurities; a first p-type semiconductor layer, which is arranged on the first n-type semiconductor layer and contains p-type impurities; an active layer, which is arranged on the first p-type semiconductor layer and has a hole portion; an intermediate layer, which is arranged on the active layer and is composed of a semiconductor that substantially does not contain n-type impurities; a second n-type semiconductor layer, which is arranged on the intermediate layer and contains n-type impurities; a first electrode, which is electrically connected to the first n-type semiconductor layer; and a second electrode, which is electrically connected to the second n-type semiconductor layer, and the intermediate layer at least covers the inner side surface of the hole portion.

[0011] Effects of the Invention

[0012] According to the nitride semiconductor light-emitting element of the present invention configured as described above, it is possible to provide a nitride semiconductor light-emitting element that can be driven at a low current and has a reduced forward voltage. BRIEF DESCRIPTION OF THE DRAWINGS

[0013] Figure 1 This is a cross-sectional view of the nitride semiconductor light-emitting element according to Embodiment 1.

[0014] Figure 2 It will Figure 1 A cross-sectional view showing an enlarged portion of the diagram.

[0015] Figure 3 It will Figure 1 Another part is enlarged and shown in a sectional view.

[0016] Figure 4 This is a cross-sectional view of a nitride semiconductor light-emitting element according to Embodiment 2. DETAILED DESCRIPTION

[0017] The following describes embodiments and examples for implementing the present disclosure with reference to the accompanying drawings. It should be noted that the nitride semiconductor light-emitting element and the method for manufacturing the nitride semiconductor light-emitting element described below are intended to embody the technical concept of the present disclosure, and unless otherwise specified, the present disclosure is not limited to the following contents.

[0018] In the various drawings, the same symbols are sometimes used to indicate components with the same functions. In order to facilitate the description or understanding of the key points, the components are sometimes divided into implementation methods and examples for convenience, but partial replacement or combination of the structures shown in different implementation methods and examples can be performed. In the implementation methods and examples described later, the description of matters common to the above-mentioned matters is sometimes omitted, and only the differences are described. In particular, the same effects based on the same structure are sometimes not mentioned in sequence in each implementation method and example. In order to clarify the description, the size, positional relationship, etc. of the components shown in the various drawings are sometimes exaggerated.

[0019] like Figure 1 As shown in , etc., the nitride semiconductor light-emitting element of the embodiment of the present disclosure includes: a first n-type semiconductor layer 20, which contains n-type impurities; a first p-type semiconductor layer 30, which is arranged on the first n-type semiconductor layer 20 and contains p-type impurities; an active layer 60, which is arranged on the first p-type semiconductor layer 30 and has a hole portion 65; an intermediate layer 70, which is arranged on the active layer 60 and is composed of a semiconductor that substantially does not contain n-type impurities; a second n-type semiconductor layer 80, which is arranged on the intermediate layer 70 and contains n-type impurities; a first electrode 11, which is electrically connected to the first n-type semiconductor layer 20; and a second electrode 12, which is electrically connected to the second n-type semiconductor layer 80.

[0020] Moreover, if Figure 3 As shown, the intermediate layer 70 covers at least the inner side surface of the hole portion 65 .

[0021] The nitride semiconductor light emitting element configured as described above can be driven at a low current and has a reduced forward voltage because the inner side surface of the hole 65 is covered with the intermediate layer 70 composed of a semiconductor containing substantially no n-type impurities.

[0022] Here, the nitride semiconductor in this specification refers to a binary to quaternary semiconductor containing at least one of aluminum (Al), gallium (Ga), and indium (In) and nitrogen (N), and can be contained in a x Al y Ga 1-x-y Semiconductors of all compositions in which the composition ratios x and y are varied within their respective ranges in a chemical formula consisting of N (0≦x≦1, 0≦y≦1, x+y≦1).

[0023] Hereinafter, the nitride semiconductor light-emitting element according to the embodiment of the present disclosure will be described in detail.

[0024] [Implementation Method 1]

[0025] Figure 1 : is a cross-sectional view of the nitride semiconductor light emitting element of embodiment 1. Figure 2 It will Figure 1 A cross-sectional view showing a portion of the enlarged portion, Figure 3 It will Figure 1 Another part is enlarged and shown in a sectional view.

[0026] like Figure 1 As shown, the semiconductor light emitting element of Embodiment 1 includes a substrate 10 , a first n-type semiconductor layer 20 disposed on the substrate 10 , a first p-type semiconductor layer 30 , an active layer 60 , an intermediate layer 70 , and a second n-type semiconductor layer 80 .

[0027] Furthermore, the nitride semiconductor light-emitting element of embodiment 1 includes: a first electrode 11, which is electrically connected to the first n-type semiconductor layer 20 by, for example, an ohmic contact with the first n-type semiconductor layer 20; and a second electrode 12, which is electrically connected to the second n-type semiconductor layer 80 by, for example, an ohmic contact with the second n-type semiconductor layer 80.

[0028] In the nitride semiconductor light-emitting element of Embodiment 1 constructed as described above, current injected from first electrode 11 disposed on first n-type semiconductor layer 20 is injected into active layer 60 via first n-type semiconductor layer 20 and first p-type semiconductor layer 30, causing active layer 60 to emit light. That is, in the nitride semiconductor light-emitting element of Embodiment 1, first electrode 11 disposed on first n-type semiconductor layer 20 serves as a positive electrode, and second electrode 12 serves as a negative electrode.

[0029] Here, as a preferred embodiment, the semiconductor light emitting element of Embodiment 1 further includes a base layer 15 disposed between the substrate 10 and the first n-type semiconductor layer 20 , a second intermediate layer 40 disposed between the first p-type semiconductor layer 30 and the active layer 60 , and a superlattice layer 50 .

[0030] Furthermore, the first n-type semiconductor layer 20 includes an n-type semiconductor layer 21 having a low n-type impurity concentration (hereinafter also referred to as low-concentration n-type semiconductor layer 21) and an n-type semiconductor layer 22 having a higher n-type impurity concentration than the low-concentration n-type semiconductor layer 21 (hereinafter also referred to as high-concentration n-type semiconductor layer 22). Furthermore, the second n-type semiconductor layer 80 includes a third n-type semiconductor layer 81 and a fourth n-type semiconductor layer 82.

[0031] The nitride semiconductor light-emitting element configured as described above is manufactured, for example, by appropriately changing the composition and growing a nitride semiconductor layer on substrate 10 to form the above-described layers. When growing the nitride semiconductor layer, the nitride semiconductor light-emitting element has a starting point within any layer between first n-type semiconductor layer 20 and active layer 60, and a hole 65 is formed from this starting point through active layer 60. The hole here refers to, for example, a V-shaped (conical) depression in cross-sectional view.

[0032] exist Figure 1 In the nitride semiconductor light emitting element shown, the hole portion 65 is, for example, Figure 3 As shown in FIG, a hole portion 65 is formed which penetrates the active layer 60 starting from the vicinity of the boundary between the second intermediate layer 40 and the superlattice layer 50. As described above, Figure 1 In the nitride semiconductor light-emitting device shown, second electrode 12 serves as a negative electrode. In a nitride semiconductor light-emitting device constructed in this manner, a nitride semiconductor layer having n-type conductivity is typically disposed between active layer 60 and second electrode 12, and the inner side surfaces of the hole are covered with the nitride semiconductor layer having n-type conductivity. However, during extensive research to reduce forward voltage, the inventors of the present application discovered that if the inner side surfaces of the hole are covered with a nitride semiconductor layer that contains substantially no n-type impurities, low current driving is possible, and the forward voltage can be reduced.

[0033] The nitride semiconductor element of the embodiment disclosed in the present invention is completed based on the insights independently obtained by the inventors of the present application as described above, and includes an intermediate layer 70 (hereinafter also referred to as the first intermediate layer) composed of a semiconductor that is substantially free of n-type impurities between the active layer 60 and the second n-type semiconductor layer 80, and the first intermediate layer 70 covers the inner surface of the hole portion 65.

[0034] The nitride semiconductor device of the embodiment configured as described above can be driven with low current and has low forward voltage because the inner side surface of the hole 65 is covered by the first intermediate layer 70 composed of a semiconductor containing substantially no n-type impurities.

[0035] This effect is believed to be achieved by suppressing the recombination of holes and electrons that do not contribute to light emission in and around the hole 65 (V-shaped pit), thereby reducing the forward voltage Vf. Specifically, it is believed that when a layer containing n-type impurities is formed on the surface (inner side) of the hole 65 (V-shaped pit) and its vicinity, recombination of holes and electrons that do not contribute to light emission occurs, increasing the forward voltage Vf.

[0036] On the other hand, if the first intermediate layer 70, which is a layer containing substantially no n-type impurities, is formed on the surface (inner side) of the hole 65 (V-shaped pit) and its vicinity, it is considered that the recombination of holes and electrons that do not contribute to light emission can be suppressed. Figure 3 As shown, it is believed that holes are injected into the active layer 60 via the first intermediate layer 70 formed on and near the surface (inner side) of the hole 65 (V-shaped pit), contributing to light emission and reducing the forward voltage Vf. The above functions and effects can be achieved as long as the first intermediate layer 70 is formed on at least a portion of the surface (inner side) of the hole 65 (V-shaped pit). Furthermore, the above functions and effects can be achieved even if the first intermediate layer 70 contains P-type impurities.

[0037] Here, in this specification, “substantially containing no n-type impurities” means less than 1×10 17 power, preferably less than 1×10 16 In other words, "substantially containing no n-type impurities" means that a layer is formed by, for example, growing the layer using a raw material gas containing no n-type impurities, and may contain n-type impurities from an adjacent n-type layer by diffusion or the like.

[0038] Hereinafter, each layer constituting the nitride semiconductor light-emitting element of Embodiment 1 will be described in detail.

[0039] <Substrate>

[0040] The material of the substrate 10 is, for example, sapphire, Si, SiC, GaN, etc. The substrate 10 may be a growth substrate for growing a nitride semiconductor layer.

[0041] <Basal layer>

[0042] The base layer 15 is a buffer layer for mitigating lattice mismatch when forming a nitride semiconductor layer on the substrate 10, and is composed, for example, of a GaN layer, an AlGaN layer, or an AlN layer that substantially does not contain n-type impurities or p-type impurities. Alternatively, the base layer 15 may be composed of a buffer layer for mitigating lattice mismatch when forming a nitride semiconductor layer on the substrate 10, and an undoped GaN layer, an AlGaN layer, or an AlN layer for reducing threading dislocations or pits. It should be noted that the thickness of the base layer is preferably, for example, not less than 0.5 μm and not more than 8 μm, and more preferably not less than 4 μm and not more than 6 μm.

[0043] <First n-type semiconductor layer 20>

[0044] The first n-type semiconductor layer 20 can be formed, for example, of a nitride semiconductor layer containing n-type impurities such as silicon (Si) and germanium (Ge). For example, when the active layer 60 is formed of a nitride semiconductor layer containing In, the nitride semiconductor forming the first n-type semiconductor layer 20 is, for example, an n-type GaN layer, which may contain In and Al. Alternatively, when the active layer 60 is formed of a nitride semiconductor containing Al, the nitride semiconductor forming the first n-type semiconductor layer 20 is, for example, an n-type AlGaN layer, which may further contain In.

[0045] Alternatively, the first n-type semiconductor layer 20 may include one or more n-type nitride semiconductor layers. In the nitride semiconductor light-emitting element of Embodiment 1, the first n-type semiconductor layer 20 includes a low-concentration n-type semiconductor layer 21 and a high-concentration n-type semiconductor layer 22. The high-concentration n-type semiconductor layer 22 is, for example, 8×10 19 Above and 8×10 20 / cm 3 The nitride semiconductor layer doped with Si as an n-type impurity at a relatively high concentration is, for example, a layer that forms a tunnel junction with the first p-type semiconductor layer 30. The high-concentration n-type semiconductor layer 22 is, for example, made of 8×10 19 Above and 8×10 20 / cm 3 The following is composed of n-type GaN doped with Si at a relatively high concentration and having a thickness of, for example, 1 nm to 10 nm.

[0046] The low-concentration n-type semiconductor layer 21 is, for example, a layer forming the first electrode 11. In order to achieve good ohmic contact with the first electrode 11, it is preferable that Si as an n-type impurity is set to 1×10 18 cm -3 Above and 5×10 19 cm -3 The low concentration n-type semiconductor layer 21 can be made of, for example, 1×10 18 cm -3 Above and 5×10 19 cm -3 The following is a composition of an n-type GaN layer containing Si as an n-type impurity.

[0047] The first n-type semiconductor layer 20 may also include an undoped semiconductor layer in part. Here, an undoped semiconductor layer refers to a layer to which n-type and p-type impurities are not intentionally added. The overall thickness of the first n-type semiconductor layer 20 is, for example, 5 μm to 15 μm.

[0048] <First p-type semiconductor layer 30>

[0049] The first p-type semiconductor layer 30 can be formed of a nitride semiconductor layer containing p-type impurities such as magnesium (Mg) and zinc (Zn). For example, if the active layer 60 is formed 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, which may contain In and Al. Alternatively, if the active layer 60 is formed of a nitride semiconductor containing Al, the nitride semiconductor forming the first p-type semiconductor layer 30 is, for example, a p-type AlGaN layer, which may further contain In.

[0050] In addition, the first p-type semiconductor layer 30 may include one or more p-type nitride semiconductor layers, and preferably includes 8×10 19 Above and 8×10 20 / cm 3 The following nitride semiconductor layer doped with Mg as a p-type impurity at a relatively high concentration is used as the uppermost layer of the first n-type semiconductor layer 20, for example, as a layer that forms a tunnel junction with the high-concentration n-type semiconductor layer 22. The layer forming a tunnel junction in the first p-type semiconductor layer 30 is composed of 8×10 19 Above and 8×10 20 / cm 3 The first p-type semiconductor layer 30 preferably includes a nitride semiconductor layer containing p-type impurities in addition to the layer for tunnel junction. The p-type impurity concentration of the nitride semiconductor layer containing p-type impurities other than the layer for tunnel junction is preferably set to 1×10 18 cm -3 Above and 2×10 20 cm -3 Next, for example, 1×10 18 cm -3 Above and 2×10 20 cm -3 The first p-type semiconductor layer 30 may be composed of a p-type GaN layer containing Mg as a p-type impurity. The first p-type semiconductor layer 30 may include an undoped semiconductor layer in part. The overall thickness of the first p-type semiconductor layer 30 may be set to, for example, 0.04 μm to 0.2 μm.

[0051] <Second Intermediate Layer 40>

[0052] Second intermediate layer 40 can be composed of a nitride semiconductor layer substantially free of n-type and p-type impurities, such as undoped GaN. This second intermediate layer 40, for example, has the function of repairing deteriorated crystallinity and surface flatness caused by the tunnel junction between first n-type semiconductor layer 20 and first p-type semiconductor layer 30, thereby improving the crystallinity of layers formed on second intermediate layer 40. The thickness of second intermediate layer 40 can be, for example, not less than 0.01 μm and not more than 0.30 μm.

[0053] <Superlattice Layer 50>

[0054] The superlattice layer 50 includes a first layer and a second layer, which are alternately stacked. For example, the lattice constant of the second layer differs from that of the first layer. By placing the superlattice layer 50 between the first p-type semiconductor layer 30 and the active layer 60 in addition to the second intermediate layer, the strain in the crystals of the active layer 60 caused by the difference in lattice constant between the first p-type semiconductor layer 30 and the active layer 60 can be reduced. By reducing the strain in the crystals of the active layer 60, the internal quantum efficiency of the active layer 60 can be improved. As a result, the luminous efficiency can be improved.

[0055] The compositions of the first and second layers are preferably set in consideration of, for example, the composition or band gap of the active layer 60, or, if the active layer 60 has a quantum well structure, the composition or band gap of the well layer. For example, if the well layer is composed of an InGaN layer, the first and second layers are preferably layers having a lower In composition ratio than the well layer.

[0056] The first layer and the second layer have different lattice constants due to, for example, different In composition ratios. At least one of the first and second layers is a layer doped with p-type impurities. By doping at least one of the first and second layers with p-type impurities, the forward voltage Vf can be reduced as described above. The p-type impurity concentration of at least one of the first and second layers is preferably 1×10 18 cm -3 Above and 3×10 19 cm -3 Furthermore, it is preferable that the concentration of the p-type impurity doped in at least one of the first layer and the second layer is lower than the p-type impurity concentration of the first p-type semiconductor layer 30 .

[0057] For example, the In composition ratio of the first layer can be greater than that of the second layer. In this case, by making the p-type impurity concentration in the first layer greater than that in the second layer, the forward voltage Vf can be easily reduced. This is believed to be because In is easily distributed near the upper surface of the first layer, thereby reducing the surface roughness of the upper surface of the first layer. Even if the first layer is doped with p-type impurities, the crystallinity of the superlattice layer 50 is unlikely to deteriorate.

[0058] In addition, when the In composition ratio of the first layer is made greater than that of the second layer and the p-type impurity concentration of the first layer is made greater than that of the second layer, the p-type impurity concentration of the first layer is preferably 1×10 18 cm -3 Above and 3×10 19 cm -3 By setting the p-type impurity concentration of the first layer within such a range, the hole supply efficiency to the active layer 60 can be improved, and degradation of the crystallinity of the superlattice layer 50 can be reduced. In this case, the second layer is preferably an undoped layer.

[0059] Furthermore, when the In composition ratio of the first layer is greater than that of the second layer, and the p-type impurity concentration of the first layer is greater than that of the second layer, the thickness of the first layer is preferably thinner than that of the second layer. By thinning the first layer having a higher p-type impurity concentration, deterioration in the crystallinity of the superlattice layer 50 can be reduced.

[0060] In particular, when the first n-type semiconductor layer 20 and the first p-type semiconductor layer 30 are tunnel-joined, as described later, the impurity concentration in the junction portion between the first n-type semiconductor layer 20 and the first p-type semiconductor layer 30 becomes high. However, by configuring the superlattice layer 50, the diffusion of impurities into the active layer 60 can be reduced, and the reduction in luminous efficiency caused by the diffusion of impurities into the active layer 60 can be effectively reduced.

[0061] The nitride semiconductor light-emitting element of embodiment 1 having a superlattice layer 50 constructed as described above can reduce the forward voltage Vf and increase the luminous intensity relative to the applied voltage by configuring the superlattice layer 50 containing p-type impurities between the first p-type semiconductor layer 30 containing p-type impurities and having p-type conductivity and the active layer 60.

[0062] Furthermore, the holes 65, formed starting from the interior of the superlattice layer 50, in other words, with their bottoms located in the superlattice layer 50, penetrate the active layer 60 to an appropriate size that allows efficient injection of holes into the active layer 60 and contributes to light emission, thereby effectively reducing the forward voltage Vf. Furthermore, the size of the holes 65 in the active layer 60 can be appropriately adjusted according to the thickness of the superlattice layer 50. For example, the overall thickness of the superlattice layer 50 is preferably not less than 45 nm and not more than 200 nm.

[0063] <Active Layer 60>

[0064] The active layer 60 is, for example, a nitride semiconductor layer that emits light with a peak wavelength within a range of 200 nm to 760 nm. The active layer 60 may have, for example, a multi-quantum well structure comprising multiple well layers and multiple barrier layers, or a single quantum well structure comprising a single well layer and barrier layers on either side thereof. When the active layer 60 is a single or multi-quantum well structure, the well layers may be, for example, GaN, InGaN, or AlGaN, and the barrier layers may be, for example, AlGaN or GaN.

[0065] <Intermediate Layer 70 (First Intermediate Layer)>

[0066] The first intermediate layer 70 is a layer disposed on the active layer 60 , and is disposed so as to cover at least a portion of the inner side surface of the hole 65 .

[0067] The first intermediate layer 70 can be composed of, for example, a nitride semiconductor layer that substantially does not contain n-type impurities such as silicon (Si) and germanium (Ge). For example, if the active layer 60 is composed of a nitride semiconductor layer containing In, the nitride semiconductor comprising the first intermediate layer 70 is, for example, an i-type GaN layer and may contain In and Al. Alternatively, if the active layer 60 is composed of a nitride semiconductor containing Al, the nitride semiconductor comprising the first intermediate layer 70 is, for example, an i-type AlGaN layer and may further contain In. Furthermore, the first intermediate layer 70 may also contain p-type impurities.

[0068] The first intermediate layer 70 is a layer that is formed on at least a portion of the inner surface of the hole 65 (V-shaped pit) and its vicinity, thereby suppressing the recombination of holes and electrons that do not contribute to luminescence, and injecting holes into the active layer 60 through the first intermediate layer 70 to contribute to luminescence, thereby reducing the forward voltage Vf.

[0069] The first intermediate layer 70 preferably covers the entire inner surface of the hole 65 . This can more effectively suppress the recombination of holes and electrons that do not contribute to light emission in the hole 65 and its vicinity, thereby further reducing the forward voltage Vf.

[0070] The thickness of the first intermediate layer 70 is, for example, not less than 2 nm and not more than 150 nm, preferably not less than 10 nm and not more than 120 nm, and more preferably not less than 40 nm and not more than 80 nm. With such a thickness, holes are supplied from the pores 65 (V-shaped pits) through the first intermediate layer 70 into the active layer 60, and the distance between the active layer 60 and the n-type semiconductor layer 80 is also shortened, thereby enabling efficient electron supply and reducing the forward voltage Vf.

[0071] <Second n-Type Semiconductor Layer 80>

[0072] The second n-type semiconductor layer 80 comprises, for example, a nitride semiconductor layer containing n-type impurities such as silicon (Si). For example, when the active layer 60 is composed of a nitride semiconductor layer containing In, the nitride semiconductor comprising the second n-type semiconductor layer 80 is, for example, an n-type GaN layer, and may also contain In and Al. Furthermore, when the active layer 60 is composed of a nitride semiconductor containing Al, the nitride semiconductor comprising the second n-type semiconductor layer 80 is, for example, an n-type AlGaN layer, and may further contain In.

[0073] The thickness of the second n-type semiconductor layer 80 can be, for example, not less than 100 nm and not more than 1500 nm, preferably not less than 200 nm and not more than 800 nm, and more preferably not less than 300 nm and not more than 500 nm. When Si is included as an n-type impurity, the impurity concentration of the second n-type semiconductor layer 80 can be, for example, 1×10 18 cm -3 Above and 5×10 19 cm -3 the following.

[0074] The second n-type semiconductor layer 80 may include one or more n-type nitride semiconductor layers, or may include an undoped semiconductor layer in part. Figure 1 As shown, the second n-type semiconductor layer 80 preferably includes a third n-type semiconductor layer 81 and a fourth n-type semiconductor layer 82 provided with the second electrode 12. The third n-type semiconductor layer 81 and the fourth n-type semiconductor layer 82 may have the same composition. For example, the third n-type semiconductor layer 81 and the fourth n-type semiconductor layer 82 may be grown using different carrier gases to have the same composition. For example, the third n-type semiconductor layer 81 may be grown using metal organic vapor deposition (MOCVD) using nitrogen (N2) as a carrier gas, and the fourth n-type semiconductor layer 82 may be grown using hydrogen (H2) as a carrier gas to have the same composition as the third n-type semiconductor layer 81. By growing the third n-type semiconductor layer 81 using metal organic vapor deposition (MOCVD) using nitrogen as a carrier gas, it is possible to easily fill the hole 65 whose inner side surface is partially or entirely covered by the first intermediate layer 70, and to easily form the third n-type semiconductor layer 81 having a flat surface. By growing the fourth n-type semiconductor layer 82 using hydrogen as a carrier gas on the third n-type semiconductor layer 81 grown using nitrogen as the carrier gas, it is possible to grow the fourth n-type semiconductor layer 82 having a surface flatter than the third n-type semiconductor layer 81. In other words, the surface roughness of the upper surface of the fourth n-type semiconductor layer 82 can be smaller than the surface roughness of the upper surface of the third n-type semiconductor layer 81.

[0075] Furthermore, the n-type impurity concentration of fourth n-type semiconductor layer 82 is preferably greater than the n-type impurity concentration of third n-type semiconductor layer 81. This reduces the contact resistance between fourth n-type semiconductor layer 82 and second electrode 12, thereby improving luminous efficiency. Furthermore, thermal diffusion of Mg remaining in the furnace and Mg in the semiconductor layer facilitates the conversion of the semiconductor layer near the surface to p-type. Therefore, for example, by increasing the n-type impurity concentration of fourth n-type semiconductor layer 82 to a greater value than the n-type impurity concentration of third n-type semiconductor layer 81, the conversion of fourth n-type semiconductor layer 82 to n-type can be facilitated.

[0076] <First and Second Electrodes>

[0077] 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., n-type semiconductor layers, and can be composed of, for example, a metal such as Au, Pt, Pd, Rh, Ni, W, Mo, Cr, Ti, Al, Cu, or an alloy containing these metals. The first electrode 11 and the second electrode 12 can have a single-layer structure or a stacked structure comprising multiple layers. For example, the first electrode 11 and the second electrode 12 can have a stacked structure comprising, in order, a Ti layer, an Al-Si-Cu alloy layer, a Ti layer, a Pt layer, an Au layer, and a Ti layer.

[0078] [Implementation Method 2]

[0079] Figure 4 This is a cross-sectional view of a nitride semiconductor light-emitting element according to Embodiment 2.

[0080] The nitride semiconductor light emitting element of embodiment 2 is as follows Figure 4 As shown, the nitride semiconductor light-emitting element of Embodiment 1 further includes a second active layer 160. The second active layer 160 is disposed on the second n-type semiconductor layer 80, and a second p-type semiconductor layer 130 is further disposed on the second active layer 160. Furthermore, the nitride semiconductor light-emitting element of Embodiment 2 includes a third electrode 110 electrically connected to the second p-type semiconductor layer 130. Here, the third electrode 110 may include a pad electrode 110b and an electrode layer 110a disposed in contact with the second p-type semiconductor layer 130. Furthermore, in the nitride semiconductor light-emitting element of Embodiment 2, the second electrode 120 is disposed, for example, on the second n-type semiconductor layer 80 exposed by removing the second active layer 160 and the second p-type semiconductor layer 130. Furthermore, the first electrode 11 is disposed on the low-concentration n-type semiconductor layer 21, similarly to the nitride semiconductor light-emitting element of Embodiment 1.

[0081] In the nitride semiconductor light-emitting element of Embodiment 2 configured as described above, the first electrode 11 functions as a positive electrode for the active layer 60. Furthermore, the third electrode 110 functions as a positive electrode for the second active layer 160. Furthermore, the second electrode 120 functions as a negative electrode for the active layer 60 (hereinafter also referred to as the first active layer 60) and the second active layer 160.

[0082] In the nitride semiconductor light-emitting element of Embodiment 2, the first active layer 60 can be caused to emit light by applying a voltage between the first electrode 11 and the second electrode 120. Furthermore, the second active layer 160 can be caused to emit light by applying a voltage between the third electrode 110 and the second electrode 120. In this manner, the first active layer 60 and the second active layer 160 can be caused to emit light independently.

[0083] In addition, even when the first active layer 60 and the second active layer 160 emit light simultaneously, the light emission intensity of the first active layer 60 and the second active layer 160 can be individually controlled by adjusting the voltage applied between the first electrode 11 and the second electrode 120 and the voltage applied between the third electrode 110 and the second electrode 120.

[0084] The nitride semiconductor light-emitting element of the second embodiment configured as described above can reduce the forward voltage Vf and improve the light emission intensity relative to the applied voltage, similarly to the nitride semiconductor light-emitting element of the first embodiment.

[0085] In the nitride semiconductor light-emitting element of embodiment 2 constructed as described above, the first active layer 60 and the second active layer 160 may have the same peak emission wavelength or different peak emission wavelengths. In addition, in the nitride semiconductor light-emitting element of embodiment 2, the second active layer 160 is located above the first active layer 60. Therefore, when the peak emission wavelength of the first active layer 60 is different from the peak emission wavelength of the second active layer 160, the color mixing property can be improved. It should be noted that by making the composition of the first active layer 60 different from that of the second active layer 160, the peak emission wavelength of the first active layer 60 can be different from that of the second active layer 160. For example, by making the In composition ratio of the first active layer 60 different from that of the second active layer 160, the peak emission wavelength of the first active layer 60 can be different from that of the second active layer 160.

[0086] Furthermore, for example, in nitride semiconductor light-emitting devices, the luminous efficiency sometimes varies depending on the peak wavelength of emission. In the nitride semiconductor light-emitting device of Embodiment 2, as described above, even when the first active layer 60 and the second active layer 160 are simultaneously illuminated, the emission intensities of the first active layer 60 and the second active layer 160 can be independently controlled by adjusting the voltage applied between the first electrode 11 and the second electrode 120 and the voltage applied between the third electrode 110 and the second electrode 120. Therefore, in the nitride semiconductor light-emitting device of Embodiment 2, even when the peak wavelength of emission of the first active layer 60 and the peak wavelength of emission of the second active layer 160 differ, different colors of emission can be achieved by adjusting the voltage applied between the first electrode 11 and the second electrode 120 and the voltage applied between the third electrode 110 and the second electrode 120.

[0087] Example

[0088] Hereinafter, embodiments of the present disclosure will be described.

[0089] In the following examples, the Figure 1 The forward voltage Vf of the nitride semiconductor light-emitting device according to the first embodiment shown was measured to confirm the effect of including the intermediate layer 70 .

[0090] Specifically, a nitride semiconductor light-emitting element of the embodiment including the intermediate layer 70 and a nitride semiconductor light-emitting element of the comparative example not including the intermediate layer 70 were produced, and the forward voltage Vf of each was measured to confirm the effect of including the intermediate layer 70 .

[0091] Furthermore, in the nitride semiconductor light emitting element of the embodiment including the intermediate layer 70 , the thicknesses of the intermediate layer 70 , the third n-type semiconductor layer 81 , and the fourth n-type semiconductor layer 82 were varied, and the forward voltage Vf was measured to confirm the thickness dependence of the effect.

[0092] Here, in the following embodiments and comparative examples, the composition and film thickness of the semiconductor layers other than the intermediate layer 70, the third n-type semiconductor layer 81 and the fourth n-type semiconductor layer 82 are shown in Table 1 below, and the composition and film thickness of the intermediate layer 70, the third n-type semiconductor layer 81 and the fourth n-type semiconductor layer 82 in Examples 1 to 4 are shown in Table 2.

[0093] Table 2 also shows the measured forward voltage Vf.

[0094] [Table 1]

[0095] semiconductor layer composition Film thickness Basal layer 15 Undoped GaN 5μm Low-concentration n-type semiconductor layer 21 <![CDATA[n-type GaN (n-type impurity concentration: 1.3×10 19 cm -3 )]]> 5μm High concentration n-type semiconductor layer 22 <![CDATA[n-type GaN (n-type impurity concentration: 4×10 20 cm -3 )]]> 5nm First p-type semiconductor layer 30 <![CDATA[p-type GaN (p-type impurity concentration: 4×10 20 cm -3 )]]> 20nm Second intermediate layer 40 Undoped GaN 20nm Superlattice layer 50 p-type InGaN / GaN superlattice 45nm First active layer 60 InGaN / GaN multiple quantum wells 55nm

[0096] [Table 2]

[0097]

[0098] Here, in Table 2, (N2) in the intermediate layer 70 (N2) and the third n-type semiconductor layer 81 (N2) indicates that the intermediate layer 70 and the third n-type semiconductor layer 81 are grown using nitrogen (N2) as a carrier gas, and (H2) in the fourth n-type semiconductor layer 82 (H2) indicates that hydrogen (H2) is used as a carrier gas to grow it.

[0099] As shown in Table 2 above, it was confirmed that the forward voltage Vf of Examples 1 to 4 including the intermediate layer 70 was lower than that of the comparative example not including the intermediate layer 70 .

[0100] The nitride semiconductor light emitting device according to the embodiment of the present invention includes the following aspects, for example.

[0101] [Item 1] A nitride semiconductor light-emitting element, comprising: a first n-type semiconductor layer containing n-type impurities; a first p-type semiconductor layer, which is arranged on the first n-type semiconductor layer and contains p-type impurities; an active layer, which is arranged on the first p-type semiconductor layer and has a hole portion; an intermediate layer, which is arranged on the active layer and is composed of a semiconductor that does not substantially contain n-type impurities; a second n-type semiconductor layer, which is arranged on the intermediate layer and contains n-type impurities; a first electrode, which is electrically connected to the first n-type semiconductor layer; and a second electrode, which is electrically connected to the second n-type semiconductor layer, wherein the intermediate layer covers at least the inner side surface of the hole portion.

[0102] [Item 2] The nitride semiconductor light-emitting element according to Item 1, wherein the intermediate layer covers the entire inner side surface of the hole.

[0103] [Item 3] The nitride semiconductor light-emitting element according to Item 1 or 2, wherein the intermediate layer contains a p-type impurity.

[0104] [Item 4] The nitride semiconductor light-emitting element according to any one of Items 1 to 3, comprising a superlattice layer disposed between the first p-type semiconductor layer and the active layer and containing p-type impurities, wherein the hole portion penetrates the superlattice layer.

[0105] [Item 5] The nitride semiconductor light-emitting element according to any one of Items 1 to 4, comprising a superlattice layer disposed between the first p-type semiconductor layer and the active layer and containing p-type impurities, wherein the bottom of the hole is located in the superlattice layer.

[0106] [Item 6] The nitride semiconductor light-emitting element according to any one of Items 1 to 5, wherein the second n-type semiconductor layer includes a third n-type semiconductor layer and a fourth n-type semiconductor layer, and the second electrode is arranged on the fourth n-type semiconductor layer.

[0107] [Item 7] The nitride semiconductor light-emitting element according to Item 6, wherein the surface roughness of the upper surface of the fourth n-type semiconductor layer is smaller than the surface roughness of the upper surface of the third n-type semiconductor layer.

[0108] [Item 8] The nitride semiconductor light-emitting element according to Item 6 or 7, wherein the n-type impurity concentration of the fourth n-type semiconductor layer is greater than the n-type impurity concentration of the third n-type semiconductor layer.

[0109] [Item 9] A nitride semiconductor light-emitting element according to any one of items 4, 5, item 6 citing item 4 or 5, and item 7 citing item 4 or 5, comprising a second intermediate layer arranged between the first p-type semiconductor layer and the superlattice layer and containing substantially no n-type impurities.

[0110] Description of Reference Numerals

[0111] 10: Substrate

[0112] 11: First electrode

[0113] 12, 120: Second electrode

[0114] 15: Basal layer

[0115] 20: First n-type semiconductor layer

[0116] 21: Low concentration n-type semiconductor layer

[0117] 22: High concentration n-type semiconductor layer

[0118] 30: First p-type semiconductor layer

[0119] 40: Second middle layer

[0120] 50: Superlattice layer

[0121] 60: Active layer, first active layer

[0122] 65: Hole

[0123] 70: Middle layer, first middle layer

[0124] 80: Second n-type semiconductor layer

[0125] 81: Third n-type semiconductor layer

[0126] 82: Fourth n-type semiconductor layer

[0127] 110: Third electrode

[0128] 110a: electrode layer

[0129] 130: Second p-type semiconductor layer

[0130] 160: Second active layer

Claims

1. A nitride semiconductor light-emitting element, characterized in that: include: a first n-type semiconductor layer comprising n-type impurities; a first p-type semiconductor layer, disposed on the first n-type semiconductor layer and containing p-type impurities; an active layer disposed on the first p-type semiconductor layer and having a hole portion; an intermediate layer, disposed on the active layer and composed of a semiconductor substantially free of n-type impurities; a second n-type semiconductor layer, disposed on the intermediate layer and comprising n-type impurities; a first electrode electrically connected to the first n-type semiconductor layer; a second electrode electrically connected to the second n-type semiconductor layer; The intermediate layer covers at least the inner side surface of the hole.

2. The nitride semiconductor light emitting element according to claim 1, wherein The intermediate layer covers the entire inner side surface of the hole portion.

3. The nitride semiconductor light emitting element according to claim 1, wherein The intermediate layer contains p-type impurities.

4. The nitride semiconductor light emitting element according to claim 1, wherein comprising a superlattice layer disposed between the first p-type semiconductor layer and the active layer and containing p-type impurities, The hole portion penetrates the superlattice layer.

5. The nitride semiconductor light emitting element according to claim 1, wherein comprising a superlattice layer disposed between the first p-type semiconductor layer and the active layer and containing p-type impurities, The bottom of the hole is located in the superlattice layer.

6. The nitride semiconductor light emitting element according to claim 1, wherein The second n-type semiconductor layer includes a third n-type semiconductor layer and a fourth n-type semiconductor layer, The second electrode is disposed on the fourth n-type semiconductor layer.

7. The nitride semiconductor light emitting element according to claim 6, wherein: The surface roughness of the upper surface of the fourth n-type semiconductor layer is smaller than the surface roughness of the upper surface of the third n-type semiconductor layer.

8. The nitride semiconductor light emitting element according to claim 6 or 7, characterized in that: The n-type impurity concentration of the fourth n-type semiconductor layer is greater than the n-type impurity concentration of the third n-type semiconductor layer.

9. The nitride semiconductor light emitting element according to claim 4 or 5, characterized in that: A second intermediate layer is included, which is disposed between the first p-type semiconductor layer and the superlattice layer and substantially does not contain n-type impurities.

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