Epitaxial structure of semiconductor light emitting element, semiconductor light emitting element, and light emitting device

Abstract

The application provides an epitaxial structure of a semiconductor light-emitting element, a semiconductor light-emitting element and a light-emitting device, and the epitaxial structure comprises at least an N-type layer, a V-pit opening layer, a light-emitting layer and a P-type layer which are sequentially stacked, wherein the light-emitting layer is an alternating stack of well layers and barrier layers, and the band gap energy of the well layer is lower than that of the barrier layer; wherein the V-pit opening layer comprises the first superlattice layer, and the distance between the bottom surface of the V-pit opening layer and the bottom surface of the second superlattice layer is less than or equal to 0.15 microns, and the distance between the bottom surface of the first superlattice layer and the thickness of the light-emitting layer is between 0.05 microns and 0.3 microns, so that the tip position of the V-surface pit is not lower than the initial position of the light-emitting layer, thereby reducing the leakage channel path in the epitaxial layer and improving the light-emitting efficiency of the LED, especially the light-emitting efficiency under low current density.

Description

Technical Field

[0001] This invention relates to the field of semiconductor devices and apparatus, and particularly to an epitaxial structure of a semiconductor light-emitting element, a semiconductor light-emitting element, and a light-emitting apparatus. Background Technology

[0002] GaN-based LEDs, due to their high luminous efficiency, are currently widely used in various light source fields such as backlighting, general lighting, automotive lighting, and decoration. From a technical perspective, further improving the luminous efficiency of LED chips remains a key focus of industry development. Luminous efficiency is mainly determined by two factors: the first is the radiative recombination efficiency of electrons and holes in the active region, i.e., the internal quantum efficiency; the second is the light extraction efficiency. There have been extensive reports on improving internal quantum efficiency, such as quantum well bandgap design, improving crystal quality, and increasing the hole injection efficiency of the p-type layer.

[0003] The epitaxial structure of a GaN-based light-emitting diode (LED) includes an n-type GaN layer, an emissive layer, and a p-type GaN layer. The emissive layer is a periodic structure composed of alternating GaN and InGaN layers. Due to the difference in lattice constants between the n-type GaN layer and the InGaN layer in the emissive layer, polarization effects and lattice mismatch easily occur, resulting in poor crystal growth quality and dislocation defects. If these dislocation defects are not effectively controlled, numerous surface defects, including V-pit defects, will be generated. To buffer the stress between the two layers, a superlattice layer and / or other low-temperature layers are typically inserted between them. The superlattice layer contains an InGaN layer with a relatively lower In content than the InGaN layer in the emissive layer, effectively buffering stress, controlling crystal growth quality, and inducing the gradual opening of V-pit defects. However, the average location of existing V-pit defects falls into the lower part of the emissive layer. For lower current densities, these V-pit defects form leakage channels, which reduce the luminous efficiency of the LED. Summary of the Invention

[0004] In view of the above-mentioned defects of GaN-based LEDs in the prior art, the present invention provides an epitaxial structure of a semiconductor light-emitting element, a semiconductor light-emitting element, and a light-emitting device to solve one or more of the above-mentioned problems.

[0005] A first aspect of this application provides an epitaxial structure for a semiconductor light-emitting element, comprising at least an N-type layer, a V-pit opening layer, a light-emitting layer, and a P-type layer stacked from bottom to top, wherein the light-emitting layer is an alternately stacked well layer and a barrier layer, and the bandgap energy of the well layer is lower than that of the barrier layer.

[0006] The V-pit opening layer includes a first superlattice layer, and the distance between the bottom surface of the V-pit opening layer and the bottom surface of the first superlattice layer is less than or equal to 0.15 μm, and the distance between the bottom surface of the first superlattice layer and the bottom surface of the light-emitting layer is between 0.05 μm and 0.3 μm; both the first superlattice layer and the light-emitting layer contain an In layer.

[0007] Optionally, the C doping concentration of the V-pit enabling layer is greater than the C doping concentration of the N-type layer, and the C doping concentration of the V-pit enabling layer is greater than or equal to 2 × 10⁻⁶. 16 Atoms / cm 3 And less than or equal to 5 × 10 17 Atoms / cm 3 The Si doping concentration of the V-pit opening layer is between 1×10⁻⁶. 17 Atoms / cm 3 ~ 1×10 19 Atoms / cm 3 between.

[0008] Optionally, the V-pit opening layer is multi-layered, and the V-pit opening layer includes at least a GaN layer;

[0009] Optionally, the thickness of the V-pit opening layer is no greater than 0.4 μm.

[0010] Optionally, the C doping concentration of the V-pit opening layer is greater than or equal to 2 × 10⁻⁶. 16 Atoms / cm 3 And less than or equal to 8 × 10 16 Atoms / cm 3 .

[0011] Optionally, the V-pit opening layer further includes a first layer structure located below the first superlattice layer; the bottom surface of the first layer structure is the bottom surface of the V-pit opening layer; the Si doping concentration in the first layer structure is between 2 × 10⁻⁶. 18 Atoms / cm 3 ~1×10 19 Atoms / cm 3 The Si doping concentration of the first layer is higher than that of the first superlattice layer and also higher than that of the upper surface of the N-type layer.

[0012] Optionally, the thickness of the first layer is less than or equal to 0.15 μm and greater than or equal to 0.02 μm.

[0013] Optionally, the V-pit opening layer further includes a third layer structure located above the first superlattice layer; the Si doping concentration of the third layer structure is higher than that of the first superlattice layer, and the Si doping concentration in the third layer structure is between 1×10⁻⁶. 18 Atoms / cm 3 ~1×10 19 Atoms / cm 3 .

[0014] Optionally, the thickness of the third layer is less than or equal to 0.1 μm and greater than or equal to 0.01 μm.

[0015] Optionally, the C doping concentration of the third layer is equal to or lower than the C doping concentration of the first superlattice layer.

[0016] Optionally, each period of the first superlattice layer of the V-pit opening layer is In. x Ga 1-x N / In y Ga 1-y N layers, and the starting layer In of the first superlattice layer y Ga 1-y N layers, with In as the terminating layer. x Ga 1-x There are N layers, where x > y, 0 < x < 1, and 0 ≤ y < 1.

[0017] Optionally, each period of the first superlattice layer of the V-pit opening layer is In. x Ga 1-x N / In y Ga 1-y N layers, and the starting layer In of the first superlattice layer x Ga 1-x N layers, with In as the terminating layer. y Ga 1-y There are N layers, where x > y, 0 < x < 1, and 0 ≤ y < 1.

[0018] Optionally, the third layer structure is an InGaN layer or a GaN layer with a lower In content than each In-containing layer in the first superlattice layer.

[0019] Optionally, each period in the first superlattice structure is In x Ga 1-x N / In y Ga 1-y N layers, where x > y, 0 < x < 1, 0 ≤ y < 1, and the thickness of the third layer is greater than the In of each period in the first superlattice layer. y Ga 1-y The thickness of layer N.

[0020] Optionally, the upper surface of the third layer structure is the bottom surface of the first light-emitting layer containing the In layer.

[0021] Optionally, the number of periods in the first superlattice layer is 3 to 7.

[0022] Optionally, between the V-pit opening layer and the light-emitting layer, a second superlattice layer is further included, the thickness of which is less than or equal to 0.1 μm and greater than or equal to 0.02 μm.

[0023] Optionally, the C doping concentration of the second superlattice layer is equal to or lower than the C doping concentration of the V-pit opening layer.

[0024] Optionally, the N-type layer includes an electron injection layer and a current spreading layer located on the electron injection layer. The current spreading layer is located between the V-pit opening layer and the electron injection layer, wherein the Si doping concentration of the electron injection layer is higher than that of the current spreading layer, and the Si doping concentration of the current spreading layer is lower than that of the V-pit opening layer.

[0025] Optionally, the thickness of the current spreading layer exceeds the distance between the bottom surface of the V-pit opening layer and the bottom surface of the first superlattice layer.

[0026] Optionally, the upper surface of the V-pit opening layer is the lower surface of the light-emitting layer.

[0027] Optionally, the V-pit opening layer further includes a third layer structure, which is the last layer of the first superlattice layer, and the first superlattice layer is In. x Ga 1-x N / In y Ga 1-y N layers, the third layer structure is In y Ga 1-y The third layer has an N-layer structure with a thickness between 0.01 μm and 0.1 μm. The Si doping concentration in the third layer is higher than that in the other layers of the first superlattice layer, and the Si doping concentration in the third layer is between 1 × 10⁻⁶. 18 Atoms / cm 3 ~1×10 19 Atoms / cm 3The thickness of the third layer is greater than the thickness of each of the remaining layers in the first superlattice layer. According to a second aspect of this application, an epitaxial structure for a semiconductor light-emitting element is provided, comprising at least, from bottom to top, an N-type electron injection layer, an N-type current spreading layer, a V-pit opening layer, a light-emitting layer, and a P-type layer, wherein the light-emitting layer is an alternately stacked well layer and a barrier layer, and the bandgap energy of the well layer is lower than the bandgap energy of the barrier layer;

[0028] The V-pit enabling layer includes a first superlattice layer, the bottom surface of which is 0.05 μm to 0.3 μm away from the bottom surface of the light-emitting layer; and the thickness of the N-type current spreading layer exceeds the distance between the bottom surface of the V-pit enabling layer and the bottom surface of the first superlattice layer.

[0029] Optionally, the C doping concentration of the V-pit enabling layer is greater than the C doping concentration of the N-type layer, and the C doping concentration of the V-pit enabling layer is greater than or equal to 2 × 10⁻⁶. 16 Atoms / cm 3 And less than or equal to 5 × 10 17 Atoms / cm 3 The Si doping concentration of the V-pit opening layer is between 1×10⁻⁶. 17 Atoms / cm 3 ~ 1×10 19 Atoms / cm 3 between.

[0030] Optionally, the V-pit enabling layer is multilayered, and the V-pit enabling layer includes at least a GaN layer and an InGaN layer. The thickness of the V-pit enabling layer is no greater than 0.4 μm, and the C doping concentration of the V-pit enabling layer is greater than or equal to 2 × 10⁻⁶. 16 Atoms / cm 3 And less than or equal to 6 × 10 18 Atoms / cm 3 .

[0031] Optionally, the V-pit opening layer further includes a first layer structure located below the first superlattice layer; the bottom surface of the first layer structure is the bottom surface of the V-pit opening layer; the first layer structure is an InGaN layer or a GaN layer with a lower In content than each In-containing layer in the first superlattice layer; the Si doping concentration in the first layer structure is between 2 × 10⁻⁶. 18 Atoms / cm 3 ~1×10 19 Atoms / cm 3The Si doping concentration of the first layer is higher than that of the first superlattice layer and also higher than that of the upper surface of the N-type layer; the distance between the bottom surface of the V-pit opening layer and the bottom surface of the first superlattice layer is the thickness of the first layer.

[0032] Optionally, the thickness of the first layer is less than or equal to 0.15 μm and greater than or equal to 0.02 μm.

[0033] Optionally, the V-pit opening layer further includes a third layer structure located above the first superlattice layer; the Si doping concentration of the third layer structure is higher than that of the first superlattice layer, and the Si doping concentration in the third layer structure is between 1×10⁻⁶. 18 Atoms / cm 3 ~1×10 19 Atoms / cm 3 .

[0034] Optionally, the thickness of the third layer is less than or equal to 0.1 μm and greater than or equal to 0.01 μm.

[0035] Optionally, the C doping concentration of the third layer is equal to or lower than the C doping concentration of the first superlattice layer.

[0036] Optionally, each period of the first superlattice layer of the V-pit opening layer is In. x Ga 1-x N / In y Ga 1-y N layers, and the starting layer In of the first superlattice layer y Ga 1-y N layers, with In as the terminating layer. x Ga 1-x N layers, where x > y, 0 < x < 1, 0 ≤ y < 1, and each period of the first superlattice layer is In. y Ga 1-y The thickness of layer N is equal.

[0037] Optionally, each period of the first superlattice layer of the V-pit opening layer is In. x Ga 1-x N / In y Ga 1-y N layers, and the starting layer In of the first superlattice layer x Ga 1-x N layers, with In as the terminating layer. y Ga 1-y There are N layers, where x > y, 0 < x < 1, and 0 ≤ y < 1.

[0038] Optionally, the first layer structure and the third layer structure are InGaN layers or GaN layers with a lower In content than each In-containing layer in the first superlattice layer.

[0039] Optionally, in each period of the first superlattice structure, In x Ga 1-x N / In y Ga 1-y N layers, where x > y, 0 < x < 1, 0 ≤ y < 1, and the thickness of the third layer is greater than the In of each period in the first superlattice layer. y Ga 1-y The thickness of layer N.

[0040] Optionally, the upper surface of the third layer structure is the bottom surface of the first light-emitting layer containing the In layer.

[0041] Optionally, the number of periods in the first superlattice layer is 3 to 7.

[0042] Optionally, between the V-pit opening layer and the light-emitting layer, a second superlattice layer is further included, the thickness of which is less than or equal to 0.1 μm and greater than or equal to 0.02 μm.

[0043] Optionally, the C doping concentration of the second superlattice layer is equal to or lower than the C doping concentration of the V-pit opening layer.

[0044] Optionally, the current spreading layer is located between the V-pit opening layer and the electron injection layer, wherein the Si doping concentration of the electron injection layer is higher than that of the current spreading layer, and the Si doping concentration of the current spreading layer is lower than that of the V-pit opening layer.

[0045] Optionally, the upper surface of the V-pit opening layer is the lower surface of the light-emitting layer.

[0046] Optionally, the V-pit opening layer further includes a third layer structure, which is the last layer of the first superlattice layer, and the first superlattice layer is In. x Ga 1-x N / In y Ga 1-y N layers, the third layer structure is In y Ga 1-y The third layer has an N-layer structure with a thickness between 0.01 μm and 0.1 μm. The Si doping concentration in the third layer is higher than that in the other layers of the first superlattice layer, and the Si doping concentration in the third layer is between 1 × 10⁻⁶. 18 Atoms / cm 3 ~ 1×10 19Atoms / cm 3 The thickness of the third layer is greater than the thickness of each of the remaining layers in the first superlattice layer. According to a third aspect of this application, a semiconductor light-emitting element is provided, comprising an epitaxial structure, said epitaxial structure being the epitaxial structure described in the first or second aspect of this application.

[0047] According to a third aspect of this application, a light-emitting device is provided, which includes the semiconductor light-emitting element provided in the third aspect of this application.

[0048] As described above, the epitaxial structure, semiconductor light-emitting element, and light-emitting device of this application have the following beneficial effects:

[0049] In this application, the V-pit opening layer includes a first superlattice layer, and the distance between the bottom surface of the V-pit opening layer and the bottom surface of the first superlattice layer is controlled to be less than or equal to 0.15 μm, and the distance between the bottom surface of the first superlattice layer and the bottom surface of the light-emitting layer is less than or equal to 0.05~0.3 μm, or the thickness of the current spreading layer exceeds the distance between the bottom surface of the V-pit opening layer and the bottom surface of the first superlattice layer. This makes the V-pit opening layer closer to the light-emitting layer and the overall thickness of the V-pit opening layer thinner. Combined with the fact that the first superlattice layer contains an In layer, while ensuring the crystal quality and luminous efficiency of the light-emitting layer, it is beneficial to ensure that most of the tips of the V-pits are inside the light-emitting layer, or all of the V-pits fall into the light-emitting layer, further reducing the leakage current path in the epitaxial layer, thereby improving the luminous efficiency under low current density. Attached Figure Description

[0050] Figure 1 The diagram shows an epitaxial structure in the prior art.

[0051] Figure 2 The image shown is a top view of the semiconductor light-emitting element provided in Embodiment 1 of the present invention.

[0052] Figure 3 Displayed as this edge Figure 2 A cross-sectional view along the LL direction shows a schematic diagram of the extensional structure within it.

[0053] Figure 4 Displayed as Figure 3 A magnified view of part A in the diagram.

[0054] Figure 5 Displayed as Figure 3 The TEM image of the epitaxial structure shown.

[0055] Figure 6 Displayed as Figure 3 The ion doping concentration of each layer in the epitaxial structure.

[0056] Figure 7 Shown as another alternative embodiment of Example 1 Figure 3 A magnified view of part A in the diagram.

[0057] Figure 8 The diagram shown is a schematic diagram of the structure of a semiconductor light-emitting element provided in Embodiment 2 of the present invention.

[0058] Figure 9 The diagram shown is a flowchart of a method for manufacturing a semiconductor light-emitting element according to Embodiment 2 of the present invention.

[0059] Figure 10 Displayed as Figure 8 The graph shows the luminous efficiency curve of the semiconductor light-emitting element.

[0060] Component designation explanation

[0061] 01: N-type GaN layer; 02: Low-temperature insertion layer; 03: Second superlattice structure; 030: V-pit; 04: Emissive layer; 05: P-type GaN layer; 100: Epitaxial structure; 101: N-type layer; 1011: Electron injection layer; 1012: Current spreading layer; 102: V-pit turn-on layer; 1021: First layer structure; 1022: Second layer structure; 1023: First superlattice layer; 1024: Third layer structure; 1031: Wide bandgap layer; 1032: Narrow bandgap layer; 104: Emissive layer; 1040: V-surface pit; 1041: Well layer; 1042: Barrier layer; 1043: Tip of V-surface pit; 105: Electron blocking layer; 1051: First sublayer; 1052 1053: Second sublayer; 106: P-type layer; 107: P-type ohmic contact layer; 108: Buffer layer; 109: Transparent conductive layer; 110: First electrode; 120: Second electrode; 200: Light-emitting diode; 103: Second superlattice layer; 201: Substrate; 202: Patterned structure; 2021: First part of the patterned structure; 2022: Second part of the patterned structure. Detailed Implementation

[0062] The following specific examples illustrate the implementation of the present invention. Those skilled in the art can easily understand other advantages and effects of the present invention from the content disclosed in this specification. The present invention can also be implemented or applied through other different specific embodiments, and various details in this specification can also be modified or changed based on different viewpoints and applications without departing from the spirit of the present invention.

[0063] like Figure 1As shown, in the prior art, the epitaxial structure of a GaN-based light-emitting diode typically includes an n-type GaN layer 01, a low-temperature insertion layer 02 (a low-temperature gallium nitride layer and / or a first superlattice structure), a second superlattice structure 03, a light-emitting layer 04, and a p-type GaN layer 05. The second superlattice structure 03 contains an InGaN layer, which has a relatively lower In content than the InGaN layer of the light-emitting layer 04, thus effectively buffering stress and improving crystal growth quality. The low-temperature insertion layer 02 (gallium nitride layer and / or the first superlattice structure) effectively reduces the growth stress of the quantum well light-emitting layer, improves the crystal quality of the quantum well light-emitting layer, and induces the gradual opening of the V-pit 030 defects.

[0064] However, in the field of existing white light illumination technology, the thickness of the low-temperature insertion layer O2 is usually quite thick, exceeding 400 nm, and the low-temperature insertion layer O2 has a high C content, exceeding 5 × 10⁻⁶. 17 Atoms / cm 3 The V-pit defects are mostly opened in the subsequent second superlattice structure 03, so that the bottom surface of the V-pit 030 is located below the light-emitting layer 04. The width of the quantum well with tilted sidewalls of the V-pit 030 is narrow, which can suppress nonradiative recombination and improve the internal quantum efficiency.

[0065] The above-mentioned design in the prior art is suitable for medium to high current densities (>20A / cm). 2 However, for lower current densities, these surface defects can create leakage paths, which reduce the luminous efficiency of the LED. To address these issues, this application provides an epitaxial structure and a semiconductor light-emitting element and device having the epitaxial structure, which will now be described in detail with reference to the following embodiments and accompanying drawings.

[0066] Example 1

[0067] This embodiment provides a semiconductor light-emitting element (also called an LED, hereinafter referred to as a light-emitting diode), such as... Figure 2 and 3 As shown, the light-emitting diode 200 includes an epitaxial structure 100, on which a first electrode 110 and a second electrode 120 are formed.

[0068] Optionally, the LED 200 can be a right-mounted or flip-mounted LED, driven by a low current density, such as less than 20A / cm². 2 The LED 200 is a small-sized chip, wherein at least one side of the chip has a dimension (e.g., side length) of less than 300 μm. The LED 200 can be used as a light source for an RGB direct-view display or as a light source for a backlight display.

[0069] In an optional embodiment, the epitaxial structure 100 of the light-emitting diode 200 is an AlGaInN-based epitaxial structure, such as... Figure 3 As shown, the epitaxial structure 100 includes an N-type layer 101, a V-pit opening layer 102, a second superlattice layer 103, a light-emitting layer 104, and a P-type layer 106 on the light-emitting layer 104, stacked sequentially. The N-type layer 101 includes an N-type electron injection layer 1011 and an N-type current spreading layer 1012, and the V-pit opening layer 102 includes a first superlattice layer 1023. The first superlattice layer 1023 and the light-emitting layer 104 are In-containing layers.

[0070] In this embodiment, the N-type electron injection layer 1011 is an N-type GaN layer used to provide electrons. The N-type electron injection layer 1011 provides electrons by doping with n-type impurities, such as Si, Ge, Sn, Se, and Te. In this embodiment, Si is preferred as the n-type impurity. The thickness of the N-type electron injection layer 1011 is approximately 1 μm to 4 μm, and the doping concentration is 1 × 10⁻⁶. 19 Atoms / cm 3 ~1×10 20 Atoms / cm 3 Between these layers, electrons are provided for radiative recombination. The N-type electron injection layer 1011 is the layer with the highest N-type doping concentration in the epitaxial structure 100. The N-type electron injection layer 1011 can be a monolayer structure or a superlattice structure (e.g., a stacked layer of two GaN layers with different doping concentrations). The N-type electron injection layer 1011 serves as both the electron injection layer and the contact layer, requiring high doping to reduce contact resistance.

[0071] In an optional embodiment, the radiation provided by the epitaxial structure is blue light or green light.

[0072] An N-type current spreading layer 1012 is grown above the N-type electron injection layer 1011 to enhance the lateral spread of the current. This current spreading layer 1012 is a relatively lightly doped N-type layer, with a Si doping concentration between 1 × 10⁻⁶. 17 Atoms / cm 3 ~2×10 18 Atoms / cm 3 Between these layers, the Si doping concentration of the current spreading layer 1012 is lower than that of the Si doping concentration of the N-type electron injection layer 1011. This current spreading layer 1012 can improve the lateral spread of the current. The thickness of the current spreading layer 1012 is less than or equal to 0.3 μm, preferably 0.01 μm or more; excessive thickness will lead to voltage increases. Figure 6 As shown, the current spreading layer 1012 is located at a depth of 0.85 μm to 1.03 μm. The growth temperature of the N-type electron injection layer 1011 and the current spreading layer 1012 is above 1000°C.

[0073] The C doping concentration of the current spreading layer 1012 is lower than that of the V-pit enabling layer 102, preferably lower than 2 × 10⁻⁶. 16 Atoms / cm 3 .

[0074] The V-pit opening layer 102 is located above the current spreading layer 1012, and is formed between the current spreading layer 1012 and the light-emitting layer 104. This allows for control of the induction process. Figure 3 The V-shaped surface pits 1040 shown are opened in the light-emitting layer 104, which can play a role in relieving stress. The V-shaped pit opening layer 102 includes at least a first superlattice layer of a certain thickness containing In, which improves the crystal quality of the light-emitting layer and enables the dislocation defects in the gallium nitride layer to be gradually opened to form V-shaped surface pits 1040.

[0075] like Figure 3 As shown, in this embodiment, in order to reduce leakage current channels, the radiative recombination ratio under low current density is increased, thereby improving luminous efficiency. By controlling the composition of the V-pit opening layer 102, the distance between it and the light-emitting layer 104, and the thickness of the V-pit opening layer 102, it is beneficial to control the V-surface pits 1040 so that the tips of most or all of the V-surface pits 1040 are not lower than the bottom surface of the initial well layer 1041 of the light-emitting layer 104, or even higher than the bottom surface of the initial well layer 1041.

[0076] The V-pit opening layer is multi-layered, including at least a gallium nitride layer and a first superlattice layer; the first superlattice layer is an In-containing layer, and the V-pit opening layer includes at least a GaN layer and an InGaN layer, or a combination of GaN and InGaN layers.

[0077] The bottom surface of the V-pit opening layer 102 is no more than 0.15 μm from the bottom surface of the first superlattice layer 1023, and the bottom surface of the first superlattice layer 1023 is between 0.05 μm and 0.3 μm from the bottom surface of the light-emitting layer 104.

[0078] The C doping concentration of the V-pit opening layer 102 is greater than or equal to 2 × 10⁻⁶. 16 Atoms / cm 3 And less than or equal to 5 × 10 17 Atoms / cm 3 The carbon doping concentration of the V-pit opening layer 102 is greater than that of the N-type layer. More preferably, the carbon doping concentration of the V-pit opening layer 102 is greater than or equal to 2 × 10⁻⁶. 16 Atoms / cm 3 And less than or equal to 8 × 10 16 Atoms / cm 3or greater than or equal to 3×10 16 Atoms / cm 3 And less than or equal to 8 × 10 16 Atoms / cm 3 or greater than or equal to 3×10 16 Atoms / cm 3 And less than or equal to 5 × 10 16 Atoms / cm 3 The C doping concentration of the V-pit opening layer 102 is greater than the C doping concentration of the N-type layer.

[0079] The V-pit opening layer 102 is located on the N-type layer 101. With a relatively low C doping concentration, it can induce the surface defects of the N-type GaN layer to open into V-pit defects at a low rate, thereby achieving uniform distribution of V-pit opening in the light-emitting layer.

[0080] Preferably, the Si doping concentration of the V-pit opening layer 102 is between 1×10⁻⁶. 17 Atoms / cm 3 ~ 1×10 19 Atoms / cm 3 The desired temperature can be obtained by using a growth temperature between 800°C and 900°C.

[0081] Preferably, the thickness of the V-pit opening layer 102 is no greater than 0.4 μm.

[0082] Preferably, the V-pit enabling layer 102 includes a first layer structure 1021 located on the current spreading layer 1012, the bottom surface of the first layer structure being the bottom surface of the V-pit enabling layer 102; the first layer structure is an InGaN layer or a GaN layer with a lower In content than each In-containing layer in the first superlattice layer.

[0083] More preferably, the first layer structure 1021 is an N-type doped GaN layer. The Si doping concentration of the first layer structure 1021 is 2 × 10⁻⁶. 18 Atoms / cm 3 ~1×10 19 Atoms / cm 3 Between these, 4×10 is better. 18 Atoms / cm 3 ~7×10 18 Atoms / cm 3 To obtain the first layer structure 1021, a GaN layer can be obtained by using a growth temperature between 800°C and 900°C.

[0084] The bottom surface of the V-pit opening layer 102 can be the bottom surface of the first layer structure 1021.

[0085] Preferably, the first layer structure 1021 has a relatively high Si doping concentration, which is greater than that of the current spreading layer 1012. The first layer structure 1021 also functions as the V-pit enabling layer 102 and, with its high Si doping, can provide protection against electrostatic discharge (ESD) damage, adjust the ESD capability of the light-emitting element, and ensure high reliability of the light-emitting element when used in backlight and display devices. More preferably, the peak Si doping concentration of the first layer structure 1021 is 2 × 10⁻⁶. 18 Atoms / cm 3 ~1×10 19 Atoms / cm 3 between.

[0086] The Si doping concentration of the first layer 1021 is also higher than the Si doping concentration of the upper surface of the N-type layer 101. In this embodiment, the Si doping concentration of the first layer 1021 is higher than the Si doping concentration of the upper surface of the current spreading layer 1012, but the Si doping concentration of the first layer 1021 is lower than the Si doping concentration of the N-type electron injection layer 1011.

[0087] Preferably, the first layer structure 1021 needs to have a certain thickness, which is less than or equal to 0.15 μm and greater than or equal to 0.02 μm. More preferably, the thickness of the first layer structure 1021 is between 0.05 and 0.10 μm.

[0088] like Figure 6 As shown, the first layer structure 1021 is distributed within a thickness range of 0.75μm to 0.85μm.

[0089] Preferably, the thickness of the current spreading layer 1012 exceeds the thickness of the first layer structure 1021, and has a lower Si doping concentration than the first layer structure 1021. That is, the thickness of the current spreading layer 1012 exceeds the distance between the bottom surface of the V-pit opening layer 102 and the bottom surface of the first superlattice layer 1021. Thus, the current spreading effect of the current spreading layer 1012 is achieved below the V-pit opening layer 102, and the bottom surface of the V-pit opening layer 102 is closer to the light-emitting layer, with the V-pits opening within the light-emitting layer.

[0090] The V-pit opening layer 102 also includes a second layer structure: a first superlattice layer 1023. The first superlattice layer 1023 is used to release the stress caused by the difference in lattice parameters of the light-emitting layer containing InGaN material grown above the GaN layer when the N-type electron injection layer 1011 is GaN, thereby improving the growth quality of the crystal and increasing the luminous brightness of the nitride light-emitting diode.

[0091] Each period of the first superlattice layer 1023 is In xGa 1-x N / In y Ga 1-y N layers, and from bottom to top, the starting layer of the first superlattice layer 1023 is In. y Ga 1-y N layers, with In as the terminating layer. x Ga 1-x N layers, or the starting layer is In x Ga 1-x N layers, with In as the terminating layer. x Ga 1-x N layers, x > y, 0 < x < 1, 0 ≤ y < 1. In this embodiment, each period of the first superlattice layer 1023 is an InGaN / GaN layer, and the starting layer of the first superlattice layer 1023 is a GaN layer, and the ending layer is an InGaN layer. The number of pairs of the first superlattice layer 1023 is 3 to 7. The first superlattice layer 1023 is also doped with Si, and similarly... Figure 6 As shown, the Si doping concentration of the first superlattice layer 1023 is between 5 × 10⁻⁶. 17 Atoms / cm 3 ~2×10 18 Atoms / cm 3 The total thickness of the first superlattice layer 1023 is between 0.05 and 0.3 μm, more preferably between 0.05 μm and 0.2 μm, for example, 0.05 to 0.15 μm. Figure 6 As shown, the first superlattice layer 1023 is located in the thickness range of 0.6μm to 0.75μm.

[0092] The bottom surface of the first superlattice layer is the bottom surface of the starting layer of the first superlattice layer 1023.

[0093] like Figure 4 As shown, optionally, the V-pit opening layer 102 may also include a third layer structure 1024 located above the first superlattice layer and below the light-emitting layer. The third layer structure is highly Si-doped and is located on both sides of the first superlattice layer with the first layer structure to play a synergistic role in preventing electrostatic damage, adjusting the ESD capability of the light-emitting element, and ensuring the high reliability of the light-emitting element in the fields of backlighting and display.

[0094] The third layer 1024 is an InGaN layer or a GaN layer. For example, the third layer 1024 is an InGaN layer or a GaN layer with a lower In content than each In-containing layer in the first superlattice layer structure. Located above the first superlattice layer 1023, the thickness of the third layer 1024 is 0.01 μm to 0.1 μm, for example, between 0.03 and 0.08 μm. (Similarly, refer to...) Figure 6The third layer structure 1024 is distributed within a thickness range of 0.55 μm to 0.6 μm. The Si doping concentration of the third layer structure is higher than that of the first superlattice layer, and the Si doping concentration in the third layer structure 1024 is between 1 × 10⁻⁶. 18 Atoms / cm 3 ~1×10 19 Atoms / cm 3 For example, between 2×10 18 Atoms / cm 3 ~ 5×10 18 Atoms / cm 3 Between. The thickness of the third layer 1024 is greater than that of each In layer in the first superlattice layer 1023. y Ga 1-y The thickness of layer N.

[0095] Preferably, each period in the first superlattice structure is In x Ga 1-x N / In y Ga 1-y N layers, where x > y, 0 < x < 1, 0 ≤ y < 1, and the thickness of the third layer is greater than the In of each period in the first superlattice layer. y Ga 1-y The thickness of layer N, with the initial layer being In. y Ga 1-y N layers, ending at layer In x Ga 1-x N layers.

[0096] Preferably, the third layer is a GaN layer, each period of the first superlattice structure includes a GaN layer, and the thickness of the GaN in the third layer is greater than the thickness of the GaN in each period of the first superlattice layer.

[0097] Optionally, as an alternative embodiment, the third layer structure 1024 can also be the last layer of the first superlattice layer 1023, where the first superlattice layer 1023 is In x G a1-x N / In y Ga 1-y N layers, with In as the starting layer. x G a1-x N layers, ending at layer In y Ga 1-y N layers, x > y, 0 < x < 1, 0 ≤ y < 1. The third layer structure is 1024, which is In. y Ga 1-yThe N-layer is, for example, a GaN layer. The thickness of the third layer structure 1024 is between 0.01 μm and 0.1 μm. The Si doping concentration of the third layer structure is higher than that of the remaining layers of the first superlattice layer, and the Si doping concentration in the third layer structure 1024 is between 1 × 10⁻⁶. 18 Atoms / cm 3 ~1×10 19 Atoms / cm 3 The thickness of the third layer 1024 is greater than the thickness of each of the other layers in the first superlattice layer 1024.

[0098] The third layer is highly Si-doped and is located on both sides of the first superlattice layer, working synergistically to prevent electrostatic damage, adjust the ESD capability of the light-emitting element, and ensure high reliability of the light-emitting element in backlight and display applications.

[0099] Optionally, such as Figure 3 As shown, a second superlattice layer 103 is formed above the V-pit opening layer 102, which is In m Ga 1-m N / In n Ga 1-n N layers, and the starting layer of the first superlattice layer is In. m Ga 1-m N layers, with In as the terminating layer. n Ga 1-n N layers, m > n, 0 < m < 1, 0 ≤ n < 1. The second superlattice layer 103 is located above the third layer structure 1024 and below the light-emitting layer. The first superlattice layer 1023 and the second superlattice layer 103 work together to release the stress generated by the InGaN material layer including the light-emitting layer above the GaN layer when the N-type electron injection layer 1011 is GaN, thereby improving the growth quality of the crystal and increasing the luminous brightness of the nitride light-emitting diode.

[0100] Preferably, the C doping concentration of the second superlattice layer 103 is equal to or lower than the C doping concentration of the V-pit opening layer 102. As an example, such as... Figure 6 As shown, the C doping concentration is lower than that of the first superlattice layer 1023. The C doping concentration of the second superlattice layer 103 is lower than 2 × 10⁻⁶. 16 Atoms / cm 3 .

[0101] Preferably, In in the second superlattice layer 103 m Ga 1-m The In content of the N layer is greater than or equal to the In content of 1023 in the first superlattice layer. x Ga 1-xThe In content in the N layer. In this embodiment, the In content in the second superlattice layer. m Ga 1-m The In content of the N layer is greater than that of the In content of the first superlattice layer (1023). x Ga 1-x The In content of the N layer. Preferably, the second superlattice layer 103 has a smaller thickness, and the total thickness of the first superlattice layer 1023 is greater than the total thickness of the second superlattice layer 103. This allows the V-pit opening layer 102 to be closer to the light-emitting layer 104, controlling that most of the V-pits are open within the light-emitting layer 104, with at least most of the bottom surfaces of the V-pits located within the light-emitting layer 104, and the second superlattice layer 103 serves to relieve stress in the light-emitting layer 104.

[0102] Reference Figure 4 In this embodiment, the second superlattice layer 103 is a periodic superlattice structure composed of alternating narrow bandgap layers 1031 and wide bandgap layers 1032. The number of periods in the superlattice structure of the second superlattice layer 103 is 3 to 5. In this embodiment, it is preferred that the number of periods in the second superlattice layer 103 is 4. Optionally, the narrow bandgap layer 1031 in the second superlattice layer 103 can be an InGaN layer, and the wide bandgap layer 1032 can be a GaN layer. Furthermore, the second superlattice layer 103 begins with an InGaN layer and ends with a GaN layer, and the Si doping concentration in the second superlattice layer 103 is between 1 × 10⁻⁶. 17 Atoms / cm 3 ~1×10 18 Atoms / cm 3 The thickness D2 of the second superlattice layer 103 is controlled to be no greater than 0.1 μm, preferably greater than 0.02 μm and less than 0.08 μm. Figure 6 In this structure, the second superlattice layer 103 is located between 0.51 μm and 0.55 μm. Within the second superlattice layer 103, the starting layer is a narrow bandgap layer 1031, which can be an InGaN layer, and the ending layer is a wide bandgap layer 1032, which is a GaN layer.

[0103] A light-emitting layer 104 is formed above the second superlattice layer 103. The light-emitting layer 104 provides a region for electron-hole recombination to provide light radiation. Different materials can be selected according to different emission wavelengths. The light-emitting layer 104 can be a periodic structure of a single quantum well or multiple quantum wells composed of a well layer and a barrier layer. By adjusting the composition ratio of the semiconductor material in the light-emitting layer 104, it is desired to radiate light of different wavelengths. In some embodiments, the light-emitting layer 104 has 5 to 15 periods of InGaN / GaN multiple quantum wells, or the light-emitting layer 104 has 5 to 15 periods of InGaN / AlGaN multiple quantum wells, and the starting layer of the light-emitting layer 104 is a well layer 1041, and the ending layer is a barrier layer 1042. The Si doping concentration of the barrier layer 1042 in the light-emitting layer 104 is between 1 × 10⁻⁶. 17 Atoms / cm 3 ~1×10 18 Atoms / cm 3 The thickness of InGaN within each cycle is 1 nm to 4 nm, and the thickness of GaN is 3 nm to 20 nm. In some embodiments, the barrier layer 1042 of the quantum well may be doped with a small amount of Al, and is composed of AlGaN. In this embodiment, as shown... Figure 4 As shown, the preferred light-emitting layer 104 is In x2 Ga (1-x2) N-well layer 1041 and Al y2 Ga (1-y2) A periodic multi-quantum-well structure consisting of N-barrier layer 1042, where 0.08≤x²≤0.18; 0.02≤y²≤0.08. Barrier layer 1042 has a larger band gap than well layer 1041.

[0104] The In content of the In-containing layer in the light-emitting layer 104 is greater than the In content of the In-containing layer in the second superlattice layer 1024.

[0105] like Figure 4 As shown, in this embodiment, in order to reduce leakage current channels, the radiative recombination ratio under low current density is increased, thereby improving luminous efficiency. The relatively close distance between the V-pit opening layer 102 and the light-emitting layer 104 makes the bottom surface of the V-pit opening layer 102 close to the bottom surface of the light-emitting layer 104. Furthermore, the V-pit opening layer 102 has a relatively thin overall thickness, and the tips of most of the V-surface pits are not lower than or even higher than the initial well layer of the light-emitting layer 104, that is, the first In-containing layer of the light-emitting layer.

[0106] The growth temperature of the V-pit opening layer 102 is lower than that of the current spreading layer 1012 and the N-type layer, which gradually induces defects such as dislocations to transform into V-surface pits 1040.

[0107] The V-pit opening layer 102 is preferably grown at a temperature between 800°C and 900°C.

[0108] Preferably, the V-pit opening layer 102 is obtained at a lower temperature, which can be lower than the growth temperature of the current spreading layer, the second superlattice layer, and the light-emitting layer. The C doping concentration is higher than that of the current spreading layer 1012 and the N-type electron injection layer 1011.

[0109] Preferably, the V-pit opening layer 102 contains Si impurities.

[0110] The V-pit opening layer 102 includes a first superlattice layer 1023 containing In. The incorporation of In effectively alleviates and releases the stress during the epitaxial structure growth process, and can also induce the V-surface pits 1040 to gradually open in subsequent growth layers. The second superlattice layer 103 can also play a synergistic role with the first superlattice layer 1023.

[0111] The V-pit opening layer 102 also includes a first layer structure 1021 located below the first superlattice layer 1023. The first layer structure 1021 is located between the first superlattice layer 1023 and the N-type electron injection layer 1011, and the Si doping concentration in the first layer structure 1021 is between 2 × 10⁻⁶. 18 Atoms / cm 3 ~1×10 19 Atoms / cm 3 The Si doping concentration of the first layer 1021 is higher than that of the first superlattice layer 1023 and also higher than that of the current spreading layer 1012.

[0112] The first layer 1021 serves to relieve stress and induce the opening of the V-surface pits 1040. Simultaneously, it has a high Si doping concentration, which improves the ESD performance of LEDs used in backlight displays or RGB displays at low current densities, addressing a key concern. Combining these two functions within a single layer structure allows for thinning of the epitaxial structure and controls the tip positions of most of the V-surface pits 1040 within the light-emitting layer, thereby reducing the leakage path and improving the luminous efficiency of the LED.

[0113] The V-pit opening layer 102 also includes a third layer structure 1024 to assist the first layer structure 1021 in releasing stress and inducing the opening of the V-surface pits 1040. This third layer structure has a high Si doping concentration and a relatively wide thickness, which can improve the ESD performance of LEDs used in backlight displays or RGB displays at low current densities. The Si doping concentration of the third layer structure 1024 can be lower than that of the first layer structure 1021, but higher than that of the first superlattice layer 1023.

[0114] When both the first layer structure 1021 and the third layer structure 1024 are GaN layers, and each period in the first superlattice layer 1023 is an InGaN / GaN layer, the thickness of the third layer structure 1024 is greater than the thickness of the GaN layer contained in each period of the first superlattice layer 1023.

[0115] To obtain the first layer structure 1021, the first superlattice layer 1023, and the third layer structure 1024, the growth temperature of the third layer structure 1024 is equal to the growth temperature of the first superlattice layer 1023, and the C doping concentration of the third layer structure 1024 is comparable to the C doping concentration of the first superlattice layer 1023; alternatively, the growth temperature of the third layer structure 1024 is higher than the growth temperature of the first superlattice layer 1023, and the C doping concentration of the third layer structure 1024 is lower than the C doping concentration of the first superlattice layer 1023. The growth temperatures of the second superlattice layer 103 and the light-emitting layer 104 are higher than the growth temperature of the V-pit opening layer 102, and the C doping concentration of the second superlattice layer 103 is lower than the C doping concentration of the V-pit opening layer 102. The C doping concentration of the second superlattice layer 103 is lower than 2 × 10⁻⁶. 16 Atoms / cm 3 The growth temperatures of the first layer 1021, the first superlattice layer 1023, and the third layer 1024 are all between 800℃ and 900℃.

[0116] like Figure 4 As shown, the V-surface pit 1040 can be a pyramid, such as a hexagonal pyramid-shaped pit. In this case, the opening width D of the V-surface pit 1040 is the maximum width of the opening of the hexagonal pyramid-shaped pit measured from the top surface of the light-emitting layer, and the tip position of the V-surface pit 1040 refers to the position of the bottom tip of the hexagonal pyramid-shaped pit measured from the top surface of the light-emitting layer. By controlling the V-surface pit 1040 as described above, the tips of most or all of the V-surface pits are located in the light-emitting layer, thereby reducing the leakage current path and improving the luminous efficiency of the LED.

[0117] like Figure 4 As shown, the thickness D0 of the V-pit opening layer 102 is no greater than 400 nm, preferably between 150 nm and 350 nm. Similarly, refer to... Figure 4 The V-pit opening layer 102 includes a first superlattice layer 1023, and the distance D1 between the bottom surface of the V-pit opening layer 102 and the bottom surface of the first superlattice layer 1023 (in this embodiment, as shown) Figure 4 As shown, the distance D1 (i.e., the thickness of the first layer structure) is controlled to be less than or equal to 150 nm, more preferably less than or equal to 100 nm or less than or equal to 50 nm.

[0118] like Figure 4As shown, a P-type layer 106 is formed above the light-emitting layer 104. This P-type layer 106 is a P-type GaN layer, which provides holes by doping with P-type impurities. The P-type impurities can be Mg, Zn, Ca, Sr, and Ba. In this embodiment, Mg is preferred as the P-type impurity. A P-type ohmic contact layer 107 is also formed above the P-type layer 106, achieved through high doping, for example, a doping concentration higher than 1 × 10⁻⁶. 20 Atoms / cm 3 This forms an ohmic contact with the P-type electrode of the subsequently formed nitride light-emitting diode. To fill the V-surface pits 1040 and improve the surface micro-pitting phenomenon of the epitaxial structure 100, the thickness of the P-type GaN layer is preferably 100 nm or more, more preferably 300 nm or less, to ensure that the P-type GaN layer can fill the V-surface pits 1040, improve the micro-pitting phenomenon of the semiconductor epitaxial stack, and thereby improve the reliability of the nitride light-emitting diode.

[0119] To prevent electron overflow, an electron blocking layer 105 is formed between the p-type layer 106 and the light-emitting layer 104. This electron blocking layer 105 can be Al. a In b Ga (1-a-b) N layers, where 0 < a ≤ 1, 0 ≤ b < 1. For example... Figure 2 As shown, preferably, the Al a In b Ga (1-a-b) Layer N comprises, from bottom to top, a first sublayer 1051, a second sublayer 1052, and a third sublayer 1052. The In content of the third sublayer 1053 is higher than that of the first and second sublayers 1051. The In content of the second sublayer 1052 can be lower or higher than that of the first sublayer 1051. The Al content of the first sublayer is higher than that of the second sublayer 1052, and the Al content of the third sublayer 1053 is higher than that of the second sublayer 1052.

[0120] A first sublayer 1051 is disposed after the light-emitting layer 104, and the first sublayer 1051 can function as an electron blocking layer 105. The first sublayer 1051 can be composed of one or more materials such as AlN, AlGaN, or AlInGaN.

[0121] The second sublayer 1052 is disposed between the first sublayer 1051 and the third sublayer 1053, and its In content is lower than that of the first sublayer 1051 and the third sublayer. It may consist of at least one AlGaN, GaN, or AlInGaN layer. The second sublayer 1052 is a hole injection layer, and its thickness is 3-70 nm. In some embodiments, the thickness of the second sublayer 1052 is preferably 8 nm or more, more preferably 10-50 nm. The P-type doping concentration of the second sublayer 1052 is 1 × 10⁻⁶. 19 Atoms / cm 3 The preferred value is 5×10. 19 Atoms / cm 3 For example, it could be 1×10 20 ~2×10 20 Atoms / cm 3 By increasing the P-type doping concentration of the second sublayer 1052, the hole injection efficiency can be improved.

[0122] The third sublayer 1053 can be composed of one or more materials such as AlN, AlGaN or AlInGaN, and can serve as an electron blocking layer 105.

[0123] Example 2

[0124] This embodiment provides the same type of light-emitting diode as an alternative to Embodiment 1. The upper surface of the V-pit opening layer 102 is in contact with the lower surface of the light-emitting layer 104, which can enable most or all of the V-pits to be opened in the light-emitting layer 104, preventing leakage.

[0125] like Figure 7 As shown, the V-pit opening layer 102 includes a first layer structure 1021, a second layer structure 1023, and a third layer structure 1024. The upper surface of the third layer structure 1024 is in contact with the lower surface of the light-emitting layer 104.

[0126] The V-pit opening layer 102 includes a first layer structure 1021 closer to the current spreading layer 1012. The first layer structure 1021 is an N-type doped GaN layer. The Si doping concentration of the first layer structure 1021 is 2 × 10⁻⁶. 18 Atoms / cm 3 ~1×10 19 Atoms / cm 3 To obtain the first layer structure 1021, a GaN layer can be obtained using a growth temperature between 800°C and 900°C.

[0127] Preferably, the first layer structure 1021 may have a relatively high Si doping concentration, which is greater than the Si doping concentration of the current extension layer 1012. The high Si doping capability of the first layer structure 1021 can play a role in preventing electrostatic damage, adjusting the ESD capability of the light-emitting element, and ensuring the high reliability of the light-emitting element in the fields of backlighting and display.

[0128] The Si doping concentration of the first layer structure 1021 is also higher than the Si doping concentration on the upper surface of the N-type layer. In this embodiment, the Si doping concentration of the first layer structure 1021 is higher than the Si doping concentration on the upper surface of the current spreading layer 1012.

[0129] Preferably, the thickness of the first layer structure 1021 is less than or equal to 0.15 μm and greater than or equal to 0.02 μm.

[0130] The V-pit opening layer 102 also includes a second layer structure: a first superlattice layer 1023. The first superlattice layer 1023 is used to release the stress caused by the difference in lattice parameters of the light-emitting layer containing InGaN material grown above the GaN layer when the N-type electron injection layer 1011 is GaN, thereby improving the growth quality of the crystal and increasing the luminous brightness of the nitride light-emitting diode.

[0131] The first superlattice layer 1023 is In x Ga 1-x N / In y Ga 1-y N layers, and the starting layer of the first superlattice layer is In. y Ga 1-y N layers, with In as the terminating layer. x Ga 1-x N layers, or the starting layer is In x Ga 1-x N layers, with In as the terminating layer. x Ga 1-x N layers, x > y, 0 < x < 1, 0 ≤ y < 1. In this embodiment, the first superlattice layer 1023 is an InGaN / GaN layer, and the starting layer of the first superlattice layer 1023 is a GaN layer, and the ending layer is an InGaN layer. The number of pairs of the first superlattice layer 1023 is 3 to 7. The first superlattice layer 1023 is also doped with Si, and the Si doping concentration of the first superlattice layer 1023 is between 5 × 10⁻⁶. 17 Atoms / cm 3 ~2×10 18 Atoms / cm 3 The thickness of the first superlattice layer 1023 is between 0.05 μm and 0.2 μm.

[0132] Optionally, the V-pit opening layer 102 further includes a third layer structure 1024 located above the first superlattice layer 1023. This third layer structure 1024 is an InGaN layer or a GaN layer, and the thickness of the GaN layer is between 0.01 μm and 0.1 μm. The Si doping concentration in the third layer structure 1024 is between 1 × 10⁻⁶. 18 Atoms / cm 3 ~ 1×10 19 Atoms / cm 3 .

[0133] Example 3

[0134] This embodiment provides the same type of light-emitting diode, such as... Figure 8 As shown, and also refer to Figure 2 The light-emitting diode 200 includes a substrate 201 and an epitaxial structure 100 formed on the substrate 201.

[0135] The width of at least one side of the light-emitting diode 200 is not more than 300 micrometers, or not more than 200 micrometers.

[0136] In optional embodiments, such as Figure 8 As shown, substrate 201 is a patterned substrate, which includes substrate 201 and patterned structures spaced apart on the upper surface of substrate 201. Substrate 201 can be an insulating substrate or a conductive substrate. Substrate 201 is a growth substrate for epitaxial growth of semiconductor epitaxial stacks, including sapphire (Al2O3). Substrate 201 includes a first surface and a second surface disposed opposite each other, with sidewalls connecting the first surface and the second surface. The plurality of patterned structures 202 on the upper surface of substrate 201 can be formed into regular and / or irregular patterns. Forming epitaxial structure 100 on the patterned substrate of this embodiment can reduce the number of dislocations in epitaxial structure 100 and improve the crystal quality of epitaxial structure 100.

[0137] The thickness of the patterned substrate is between 40μm and 150μm. For example, the thickness of the patterned substrate is above 40μm and below 80μm, or even thinner than 40μm and below 60μm.

[0138] To reduce the lattice mismatch between the patterned substrate and the N-type electron injection layer 1011, a buffer layer 108 is grown between the patterned substrate and the N-type electron injection layer 1011. Therefore, the lattice constant of the buffer layer 108 is between that of the patterned substrate and the N-type electron injection layer 1011, and it can be composed of Al... x1 In y1 Ga (1-x1-y1)The material is made of N, where 0≤x1≤1 and 0≤y1≤1, and can specifically be an AlN layer, GaN layer, AlGaN layer, AlInGaN layer, InGaN layer, etc. The buffer layer 108 can be formed by MOCVD or PVD. In some embodiments, the buffer layer 108 preferably includes a 25nm~40nm thick low-temperature GaN nucleation layer, a 0.2μm~1μm thick high-temperature GaN buffer layer 108, and a 1μm~2μm thick two-dimensional GaN layer.

[0139] Reference Figure 8 An epitaxial structure is formed above the buffer layer 108. This epitaxial structure is the epitaxial structure 100 described in Embodiment 1, which can be referred to in the description of Embodiment 1 for details, and will not be repeated here. The above structure of the patterned substrate, combined with the V-pit opening layer 102 of the epitaxial structure 100, and the synergistic effect between the V-pit opening layer 102 and the In-containing layer of the first superlattice layer 1023, ensures that the tip of the V-surface pit 1040 is mostly not lower than the beginning of the initial well layer 1041 of the light-emitting layer, thereby reducing the leakage current path in the epitaxial layer and improving the luminous efficiency of the LED, especially the luminous efficiency at low current densities. Figure 10 As shown, at low current densities (0~20 A / cm²) 2 Under these conditions, the light-emitting diode 200 of this application has a significantly improved luminous efficiency compared to existing light-emitting diodes, especially in the range of 0~15 A / cm². 2 Within this range, the luminous efficiency is improved more significantly, up to a maximum of more than 3 times.

[0140] Similarly, refer to Figure 8 and Figure 2 The light-emitting diode 200 further includes an electrode structure comprising a first electrode 110 and a second electrode 120. The first electrode 110 is formed above the N-type electron injection layer 1011 and communicates with the N-type layer. The second electrode 120 is formed above the P-type layer 106 and communicates with the P-type layer 106. A transparent conductive layer 109 may also be formed between the second electrode 120 and the P-type layer 106. The transparent conductive layer 109 can form an ohmic contact with the P-type layer 106. The transparent conductive layer 109 is an oxide containing at least one selected from Zn, In, Sn, and Mg, specifically ZnO, In2O3, SnO2, ITO, IZO, GZO, etc. In this embodiment, the transparent conductive layer 109 is preferably ITO.

[0141] This embodiment also provides a method for manufacturing the above-mentioned light-emitting diode, such as... Figure 9 As shown, the method includes the following steps:

[0142] S100: Provide a substrate having a surface with a periodically arranged patterned structure;

[0143] Similarly, refer to Figure 8 The substrate 201 is the patterned substrate described above, which includes the substrate 201 and patterned structures 202 disposed at intervals on the upper surface of the substrate 201. The patterned structures 202 have the structural features described above, which will not be repeated here.

[0144] S200: An N-type layer is grown on the surface;

[0145] Reference Figure 8 An N-type electron injection layer 1011 is grown on the surface of the patterned structure 202 on the substrate 201. Preferably, to reduce the lattice mismatch between the patterned substrate and the N-type electron injection layer 1011, a buffer layer 108 is first grown on the patterned substrate. The lattice constant of the buffer layer 108 is between that of the patterned substrate and the N-type layer 101, and it can be composed of Al... x1 In y1 Ga (1-x1-y1) The material is made of N, where 0≤x1≤1 and 0≤y1≤1, and can specifically be an AlN layer, GaN layer, AlGaN layer, AlInGaN layer, InGaN layer, etc. The buffer layer 108 can be formed by MOCVD or PVD. In some embodiments, the buffer layer 108 preferably includes a 25nm~40nm thick low-temperature GaN nucleation layer, a 0.2μm~1μm thick high-temperature GaN buffer layer 108, and a 1μm~2μm thick two-dimensional GaN layer.

[0146] Then, an N-type electron injection layer 1011 is grown above the buffer layer 108. The N-type electron injection layer 1011 is an N-type GaN layer used to provide electrons. The N-type electron injection layer 1011 provides electrons by doping with an n-type impurity, such as Si, Ge, Sn, Se, and Te. In this embodiment, Si is preferred as the n-type impurity. The thickness of the N-type electron injection layer 1011 is approximately 1 μm to 4 μm, and the doping concentration is 1 × 10⁻⁶. 19 Atoms / cm 3 ~1×10 20 Atoms / cm 3 Between these layers, electrons are provided for radiative recombination. The N-type electron-injected layer 1011 can be a monolayer structure or a superlattice structure. The growth temperature is above 1000℃, for example, between 1050℃ and 1150℃.

[0147] S300: A V-pit opening layer is formed above the N-type layer at a temperature of 800~900℃;

[0148] Similarly, refer to Figure 8 and Figure 3Before forming the V-pit opening layer 102, an N-type current spreading layer 1012 is first formed above the N-type electron injection layer 1011 at a growth temperature of over 1000°C. Then, the temperature is lowered to 800°C~900°C, and a first layer structure 1021, a first superlattice layer 1023, and a third layer structure 1024 are sequentially grown above the current spreading layer 1012.

[0149] In this embodiment, the V-pit opening layer 102 is formed at a relatively low temperature (e.g., 800°C to 900°C).

[0150] More preferably, the C doping concentration of the V-pit opening layer 102 is not higher than 8 × 10⁻⁶. 16 Atoms / cm 3 This allows us to control the bottom of the V-surface pit in the subsequently formed luminescent layer to be located within the luminescent layer.

[0151] S400: A second superlattice layer is formed above the V-pit opening layer, and the growth temperature is between 900℃ and 1100℃;

[0152] A second superlattice layer 103 is formed above the aforementioned V-pit opening layer 102 to release the stress generated during the growth of the N-type electron injection layer 1011. Optionally, as... Figure 4 As shown, the second superlattice layer 103 is a periodic superlattice structure composed of alternating narrow bandgap layers 1031 and wide bandgap layers 1032, wherein the wide bandgap layer 1032 is Al y1 Ga (1-y1) N, narrow bandgap layer 1031 is In x1 Ga (1-x1) N, wherein preferably 0.04≤x1≤0.12; 0≤y1≤0.06. In this embodiment, the number of periods of the second superlattice layer 103 is preferably 3. Optionally, the narrow bandgap layer 1031 in the second superlattice layer 103 may be an InGaN layer, and the wide bandgap layer 1032 may be a GaN layer. Furthermore, the second superlattice layer 103 begins with an InGaN layer and ends with a GaN layer.

[0153] S500: A light-emitting layer is formed by alternately stacking well layers and barrier layers above the second superlattice layer, wherein the band gap energy of the well layer is lower than that of the barrier layer, and the light-emitting layer contains V surface pits.

[0154] Reference Figure 4 Preferably, In is sequentially formed above the second superlattice layer 103. x2 Ga (1-x2) N-well layer 1041 and Al y2 Ga (1-y2)A periodic multiple quantum well structure composed of an N-type barrier layer 1042, wherein 0.08 ≤ x² ≤ 0.18; 0.02 ≤ y² ≤ 0.08. The barrier layer 1042 has a larger band gap than the well layer 1041. By adjusting the composition ratio of the semiconductor material in the light-emitting layer 104, it is desired to emit light of different wavelengths. In some embodiments, the light-emitting layer 104 has 5 to 15 periods of InGaN / GaN multiple quantum wells, and the starting layer of the light-emitting layer 104 is an InGaN layer, and the ending layer is a GaN layer. The Si doping concentration in the light-emitting layer 104 is between 1 × 10⁻⁶. 17 Atoms / cm 3 ~1×10 18 Atoms / cm 3 The total thickness does not exceed 0.1 μm. The thickness of InGaN in each cycle is 1 nm to 4 nm, and the thickness of each GaN layer is 3 nm to 15 nm. In some embodiments, the barrier layer 1042 of the quantum well may be doped with a small amount of Al, and is composed of AlGaN. Due to the difference in lattice constants between the GaN layer and the InGaN layer, polarization effects are easily generated, leading to dislocation defects. If these dislocation defects are not effectively controlled, a large number of surface defects will be formed, such as V-pits 1040. V-pits 1040 form leakage channels, reducing the luminous efficiency of the LED.

[0155] Because a V-pit opening layer 102 is formed above the N-type electron injection layer 1011, under the action of the V-pit opening layer 102, the position of the tip of the V-surface pit 1040 in the light-emitting layer 104 is not lower than the starting position of the initial well layer 1041 of the light-emitting layer, that is... Figure 3 The starting position of the well layer 1041 adjacent to the N-type electron injection layer 1011 is shown. Furthermore, the opening width D at the surface of the last barrier layer 1042 of the light-emitting layer 104 is less than 200 nm. This V-surface pit 1040 can be a pyramid, such as a hexagonal pyramid-shaped pit, in which case the opening width D of the V-surface pit 1040 is the maximum width at the opening of the hexagonal pyramid-shaped pit. Through the above control of the V-surface pit 1040, as... Figure 4 As shown, the hole injection channel is narrowed, thereby reducing the leakage current path and improving the luminous efficiency of the LED.

[0156] S600: A P-type layer is formed above the light-emitting layer.

[0157] The P-forming layer is a P-type GaN layer, which provides holes by doping with P-type impurities. The P-type impurities can be Mg, Zn, Ca, Sr, and Ba. In this embodiment, Mg is preferred as the P-type impurity. A P-type ohmic contact layer 107 is also formed above the P-type layer 106, achieved through high doping, for example, a doping concentration higher than 1 × 10⁻⁶. 20 Atoms / cm 3It forms an ohmic contact with the P-type electrode of the nitride light-emitting diode. In order to fill the V-surface pit 1040, the thickness of the P-type GaN layer is preferably more than 100 nm, more preferably less than 300 nm, so as to ensure that the P-type GaN layer can fill the V-surface pit 1040, improve the micro-pit phenomenon of semiconductor epitaxial stack, and thus improve the reliability of the nitride light-emitting diode.

[0158] To prevent electron overflow, an electron blocking layer 105 is first formed above the light-emitting layer 104 before forming the p-type layer 106. This electron blocking layer 105 can be Al. a In b Ga (1-a-b) N layers, where 0 < a ≤ 1, 0 ≤ b < 1.

[0159] Finally, a first electrode 110 and a second electrode 120 are formed above the N-formation and P-formation of the light-emitting diode 200, respectively.

[0160] Example 4

[0161] This embodiment provides a light-emitting device, which includes a circuit board and a light-emitting element disposed on the circuit board, wherein the light-emitting element may be a light-emitting diode as provided in Embodiment 2 of this application. The light-emitting device is an LED backlight device or an RGB display screen device.

[0162] The above embodiments are merely illustrative of the principles and effects of the present invention and are not intended to limit the invention. Any person skilled in the art can modify or alter the above embodiments without departing from the spirit and scope of the present invention. Therefore, all equivalent modifications or alterations made by those skilled in the art without departing from the spirit and technical concept disclosed in the present invention should still be covered by the claims of the present invention.

Claims

1. An epitaxial structure for a semiconductor light-emitting element, characterized in that, It includes at least an N-type layer, a V-pit opening layer, a light-emitting layer and a P-type layer stacked from bottom to top, wherein the light-emitting layer is an alternately stacked well layer and a barrier layer, and the band gap energy of the well layer is lower than that of the barrier layer. The V-pit opening layer includes a first superlattice layer, and the V-pit opening layer also includes a first layer structure located below the first superlattice layer; the bottom surface of the first layer structure is the bottom surface of the V-pit opening layer. Furthermore, the distance between the bottom surface of the V-pit opening layer and the bottom surface of the first superlattice layer is less than or equal to 0.15 μm, and the distance between the bottom surface of the first superlattice layer and the bottom surface of the light-emitting layer is between 0.05 μm and 0.3 μm; both the first superlattice layer and the light-emitting layer are In-containing layers; The first layer structure is an InGaN layer or a GaN layer with a lower In content than each In-containing layer in the first superlattice layer.

2. The epitaxial structure of the semiconductor light-emitting element according to claim 1, characterized in that, The C doping concentration of the V-pit enabling layer is greater than the C doping concentration of the N-type layer, and the C doping concentration of the V-pit enabling layer is greater than or equal to 2 × 10⁻⁶. 16 Atoms / cm 3 And less than or equal to 5 × 10 17 Atoms / cm 3 The Si doping concentration of the V-pit opening layer is between 1×10⁻⁶. 17 Atoms / cm 3 ~ 1×10 19 Atoms / cm 3 between.

3. The epitaxial structure of the semiconductor light-emitting element according to claim 2, characterized in that, The C doping concentration of the V-pit opening layer is greater than or equal to 2 × 10⁻⁶. 16 Atoms / cm 3 And less than or equal to 8 × 10 16 Atoms / cm 3 .

4. The epitaxial structure of the semiconductor light-emitting element according to claim 2, characterized in that, The V-pit opening layer is multi-layered, and the V-pit opening layer includes at least a GaN layer.

5. The epitaxial structure of the semiconductor light-emitting element according to claim 2, characterized in that, The thickness of the V-pit opening layer is no greater than 0.4 μm.

6. The epitaxial structure of the semiconductor light-emitting element according to claim 1, characterized in that, The Si doping concentration in the first layer structure is between 2 × 10⁻⁶. 18 Atoms / cm 3 ~1×10 19 Atoms / cm 3 The Si doping concentration of the first layer is higher than that of the first superlattice layer and also higher than that of the upper surface of the N-type layer.

7. The epitaxial structure of the semiconductor light-emitting element according to claim 6, characterized in that, The thickness of the first layer is less than or equal to 0.15 μm and greater than or equal to 0.02 μm.

8. The epitaxial structure of the semiconductor light-emitting element according to claim 1, characterized in that, The V-pit opening layer further includes a third layer structure located above the first superlattice layer; the Si doping concentration of the third layer structure is higher than that of the first superlattice layer, and the Si doping concentration in the third layer structure is between 1×10⁻⁶. 18 Atoms / cm 3 ~1×10 19 Atoms / cm 3 .

9. The epitaxial structure of the semiconductor light-emitting element according to claim 8, characterized in that, The thickness of the third layer is less than or equal to 0.1 μm and greater than or equal to 0.01 μm.

10. The epitaxial structure of the semiconductor light-emitting element according to claim 8, characterized in that, The C doping concentration of the third layer is equal to or lower than the C doping concentration of the first superlattice layer.

11. The epitaxial structure of the semiconductor light-emitting element according to claim 8, characterized in that, Each period of the first superlattice layer of the V-pit opening layer is In x Ga 1-x N / In y Ga 1-y N layers, and the starting layer In of the first superlattice layer y Ga 1-y N layers, with In as the terminating layer. x Ga 1-x There are N layers, where x > y, 0 < x < 1, and 0 ≤ y < 1.

12. The epitaxial structure of the semiconductor light-emitting element according to claim 8, characterized in that, Each period of the first superlattice layer of the V-pit opening layer is In x Ga 1-x N / In y Ga 1-y N layers, and the starting layer In of the first superlattice layer x Ga 1-x N layers, with In as the terminating layer. y Ga 1-y There are N layers, where x > y, 0 < x < 1, and 0 ≤ y < 1.

13. The epitaxial structure of the semiconductor light-emitting element according to claim 8, characterized in that, The third layer structure is an InGaN layer or a GaN layer with a lower In content than each In-containing layer in the first superlattice layer.

14. The epitaxial structure of the semiconductor light-emitting element according to claim 13, characterized in that, Each period in the first superlattice layer is In x Ga 1-x N / In y Ga 1-y N layers, where x > y, 0 < x < 1, 0 ≤ y < 1, and the thickness of the third layer is greater than the In of each period in the first superlattice layer. y Ga 1-y The thickness of layer N.

15. The epitaxial structure of the semiconductor light-emitting element according to claim 8, characterized in that, The upper surface of the third layer structure is the bottom surface of the first layer containing the In layer in the light-emitting layer.

16. The epitaxial structure of the semiconductor light-emitting element according to claim 1, characterized in that, The number of periods in the first superlattice layer is 3 to 7.

17. The epitaxial structure of the semiconductor light-emitting element according to claim 1, characterized in that, Between the V-pit opening layer and the light-emitting layer, there is also a second superlattice layer, the thickness of which is less than or equal to 0.1 μm and greater than or equal to 0.02 μm.

18. The epitaxial structure of the semiconductor light-emitting element according to claim 17, characterized in that, The C doping concentration of the second superlattice layer is equal to or lower than the C doping concentration of the V-pit opening layer.

19. The epitaxial structure of the semiconductor light-emitting element according to claim 1, characterized in that, The N-type layer includes an electron injection layer and a current spreading layer located on the electron injection layer. The current spreading layer is located between the V-pit opening layer and the electron injection layer. The Si doping concentration of the electron injection layer is higher than that of the current spreading layer, and the Si doping concentration of the current spreading layer is lower than that of the V-pit opening layer.

20. The epitaxial structure of the semiconductor light-emitting element according to claim 19, characterized in that, The thickness of the current spreading layer exceeds the distance between the bottom surface of the V-pit opening layer and the bottom surface of the first superlattice layer.

21. The epitaxial structure of the semiconductor light-emitting element according to claim 1, characterized in that, The upper surface of the V-pit opening layer is the lower surface of the light-emitting layer.

22. The epitaxial structure of the semiconductor light-emitting element according to claim 1, characterized in that, The V-pit opening layer further includes a third layer structure, which is the last layer of the first superlattice layer, and the first superlattice layer is In. x Ga 1-x N / In y Ga 1-y N layers, the third layer structure is In y Ga 1-y The third layer has an N-layer structure with a thickness between 0.01 μm and 0.1 μm. The Si doping concentration in the third layer is higher than that in the other layers of the first superlattice layer, and the Si doping concentration in the third layer is between 1 × 10⁻⁶. 18 Atoms / cm 3 ~ 1×10 19 Atoms / cm 3 The thickness of the third layer is greater than the thickness of each of the other layers in the first superlattice layer.

23. A semiconductor light-emitting element, characterized in that, It includes an epitaxial structure, wherein the epitaxial structure is the epitaxial structure described in any one of claims 1 to 22.

24. A light-emitting device, characterized in that, It includes the semiconductor light-emitting element as described in claim 23.

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