Gallium nitride light emitting diode epitaxial structure, LED and preparation method thereof

Abstract

The application relates to the technical field of semiconductors, and particularly discloses a gallium nitride light-emitting diode epitaxial structure, an LED and a preparation method thereof, which comprises a substrate, a buffer layer, an N-type layer, a multi-quantum well layer and a P-type layer arranged in sequence, a potential barrier adjusting layer is arranged between the multi-quantum well layer and the P-type layer, the potential barrier adjusting layer comprises Al a N layers, Al b In x Ga 1‑b‑x N layers, In 1‑c Al c N layers and N-polar Al d GaN / N-polar MgN superlattice layers deposited in the epitaxial direction in sequence. The potential barrier adjusting layer is jointly matched by the multi-layer material layers, which effectively increases and accelerates hole injection while reducing electron overflow, enhances the conductivity and hole injection rate of the P-type layer, and thus effectively improves the light-emitting efficiency.

Description

Technical Field

[0001] This invention relates to the field of semiconductor technology, and in particular to a gallium nitride light-emitting diode epitaxial structure, an LED, and a method for fabricating the same. Background Technology

[0002] Semiconductor light-emitting diodes (LEDs) possess advantages such as small size, robustness, high controllability of emission wavelength, high luminous efficiency, low heat loss, low light decay, energy saving, and environmental friendliness. They are widely used in full-color displays, backlights, signal lights, optoelectronic computer interconnection, and short-range communication, and are gradually becoming a research hotspot in the field of electronic power engineering. Gallium nitride (GaN) materials have a series of advantages, including wide bandgap, high electron mobility, high thermal conductivity, and high stability, thus enjoying wide application and a huge market prospect in high-brightness blue LEDs. The lighting industry is placing increasingly higher demands on LEDs, and improving the luminous efficiency and brightness of GaN-based LEDs while reducing production costs is a key focus for the LED industry.

[0003] Currently, due to the inherent polarization effect of GaN-based materials, the resulting Stark effect causes band bending in multiple quantum wells, reducing the overlap of wave functions and thus reducing the effective recombination efficiency of holes and electrons. On the other hand, although the current electron blocking layer blocks the electron overflow in the quantum well, it also reduces the injection efficiency of holes from the P-type GaN layer, further reducing the luminescence efficiency. Summary of the Invention

[0004] The purpose of this invention is to address the existing technological limitations by providing a gallium nitride (GaN) light-emitting diode (LED) epitaxial structure, an LED, and a method for fabricating the same. The barrier modulation layer of this invention is prepared using Al... a N layer, Al b In x Ga 1-b-x N-layer, In 1-c Al c N-layer and N-polarity Al d The combined use of multiple GaN / N polar MgN superlattice layers effectively increases and accelerates hole injection while reducing electron overflow, thereby enhancing the conductivity and hole injection rate of the P-type layer and thus effectively improving luminescence efficiency.

[0005] To achieve the above objectives, the present invention adopts the following technical solution:

[0006] Firstly, as one of the objectives of this invention, this invention provides a gallium nitride light-emitting diode epitaxial structure, comprising a substrate, a buffer layer, an N-type layer, a multi-quantum-well layer, and a P-type layer sequentially disposed therefrom. A barrier modulation layer is provided between the multi-quantum-well layer and the P-type layer, and the barrier modulation layer comprises Al atoms sequentially deposited along the epitaxial direction. a N layer, Al b Inx Ga 1-b-x N-layer, In 1- c Al c N-layer and N-polarity Al d GaN / N polar MgN superlattice layer.

[0007] In some embodiments, in the barrier tuning layer, 0 < d < c < b < a < 1, 0 < x < 1 - c < 1.

[0008] In some embodiments, the Al a N layers, the Al b In x Ga 1-b-x N layers and the In 1-c Al c In the N-layer, the Al content in each layer decreases along the epitaxial direction, and the N-polar Al... d In the GaN / N polar MgN superlattice layer, the Al content increases along the epitaxial direction.

[0009] In some embodiments, the Al a N layers, the Al b In x Ga 1-b-x N layers, the In 1-c Al c N-layer and the N-polarity Al d In the GaN / N polar MgN superlattice layer, the decrease in Al content between layers, i, is 0.01 < i ≤ 0.1;

[0010] The Al a N layers, the Al b In x Ga 1-b-x N layers and the In 1-c Al c In the N layers, the decrease in Al content in each layer is j such that 0 < j ≤ 0.01, and the N-polar Al... d In the GaN / N polar MgN superlattice layer, the increment of Al content k is 0 < k ≤ 0.01.

[0011] In some embodiments, the Al a N layers, the Al b In x Ga 1-b-x N layers and the In 1-c Al c The thickness of layer N decreases sequentially, and the Al a The thickness of the N layer is 4nm to 5nm, and the Al b In xGa 1-b-x The thickness of the N layer is 3nm to 4nm, and the In 1- c Al c The thickness of the N layer is 2nm to 3nm, and the N-polar Al d The thickness of the GaN / N polar MgN superlattice layer is 2 nm to 5 nm.

[0012] In some embodiments, the N-polarity Al d The growth atmosphere for the GaN / N polar MgN superlattice layer is N2.

[0013] In some embodiments, the N-polarity Al d The GaN / N-polar MgN superlattice layer includes periodically alternating N-polar Al atoms. d The growth cycle of GaN sublayer and N-polar MgN sublayer is 3 to 5.

[0014] In some embodiments, the In 1-c Al c The growth pressure of the N layer is higher than that of the Al layer. b In x Ga 1-b-x Growth pressure on the N-layer.

[0015] Secondly, as another objective of this invention, this invention provides a method for fabricating a gallium nitride light-emitting diode epitaxial structure, comprising:

[0016] Provide substrate;

[0017] A buffer layer, an N-type layer, a multiple quantum well layer, a barrier tuning layer, and a P-type layer are epitaxially grown sequentially on the substrate.

[0018] The barrier conditioning layer comprises Al layers deposited sequentially along the epitaxial direction. a N layer, Al b In x Ga 1-b-x N-layer, In 1-c Al c N-layer and N-polarity Al d GaN / N polar MgN superlattice layer.

[0019] Furthermore, as another objective of the present invention, the present invention provides an LED comprising the above-described gallium nitride light-emitting diode epitaxial structure.

[0020] The beneficial effects of this invention are as follows:

[0021] In this invention, a barrier modulation layer composed of multiple material layers is introduced between the multi-quantum well layer and the P-type layer, wherein Al... aThe N-layer forms a high barrier energy level, blocking electron migration and ensuring that the barrier matching layer has good crystal quality. This ensures that the stress field generated by the lattice fitting stress is small, thereby improving the effective injection of holes; secondly, Al b In x Ga 1-b-x N layers and In 1-c Al c Introducing In composition into the N layer lowers the potential barrier height. Combined with the higher barrier height of the AlaN layer, this reduces electron overflow and decreases the leakage path, while simultaneously reducing the energy required for hole injection and increasing hole injection capacity. Furthermore, the combination of N-polar Al... d The GaN / N-polar MgN superlattice layer utilizes the polarity of N, with the polarization electric field oriented in the same direction as the external electric field. The polarization field and the external electric field together accelerate hole injection into the quantum well layer, further improving carrier injection efficiency and increasing the luminescence efficiency of the quantum well layer. Simultaneously, the N-polar Al... d The N-polar MgN sublayer in the GaN / N-polar MgN superlattice layer generates a high concentration of three-dimensional hole gas due to polarization doping, effectively enhancing the conductivity and hole injection rate of the P-type layer. Consequently, the barrier tuning layer, via Al... a N layer, Al b In x Ga 1-b-x N-layer, In 1-c Al c N-layer and N-polarity Al d The combined use of multiple GaN / N polar MgN superlattice layers effectively increases and accelerates hole injection while reducing electron overflow, thereby enhancing the conductivity and hole injection rate of the P-type layer and thus effectively improving luminescence efficiency. Attached Figure Description

[0022] Figure 1 This is a schematic diagram of the epitaxial structure of the gallium nitride light-emitting diode of the present invention.

[0023] Figure 2 This is a flowchart illustrating the method for fabricating the gallium nitride light-emitting diode epitaxial structure of the present invention.

[0024] Figure 3 This is a flowchart of the method for preparing the barrier modulation layer of the present invention. Detailed Implementation

[0025] To make the objectives, technical solutions, and advantages of this invention clearer, the invention will be described in further detail below.

[0026] Please see Figure 1As shown, this invention discloses a gallium nitride light-emitting diode epitaxial structure, comprising a substrate 1, a buffer layer 2, an N-type layer 3, a multiple quantum well layer 4, and a P-type layer 6 sequentially disposed thereon. A barrier modulation layer 5 is disposed between the multiple quantum well layer 4 and the P-type layer 6. The barrier modulation layer 5 comprises Al atoms sequentially deposited along the epitaxial direction. a N layer 51, Al b In x Ga 1-b-x N layer 52, In 1-c Al c N-layer 53 and N-polarity Al d GaN / N polar MgN superlattice layer 54.

[0027] In this invention, a barrier modulation layer 5 composed of multiple material layers is introduced between the multi-quantum well layer 4 and the P-type layer 6, wherein, through Al a Layer N51 forms a high barrier energy level, blocking electron migration and ensuring that barrier matching layer 5 has good crystal quality, ensuring that the stress field generated by the lattice fitting stress is small, thereby improving the effective injection of holes; secondly, Al b In x Ga 1-b-x N layer 52 and In 1-c Al c Introducing In component into layer N53 lowers the barrier height, allowing it to interact with Al, which has a higher barrier height. a The N-layer 51 phase combination reduces electron overflow and lowers the leakage path, while simultaneously reducing the energy required for hole injection and increasing hole injection; combined with N-polarity Al d The GaN / N-polar MgN superlattice layer 54 utilizes the polarity of N, with the polarization electric field and external electric field oriented in the same direction. The polarization field and external electric field together accelerate hole injection into the quantum well layer, further improving carrier injection efficiency and increasing the luminescence efficiency of the quantum well layer. Simultaneously, the N-polar Al... d Due to the polarization doping effect, the N-polar MgN sublayer in the GaN / N-polar MgN superlattice layer 54 generates a high concentration of three-dimensional hole gas, effectively enhancing the conductivity and hole injection rate of the P-type layer 6. Consequently, the barrier tuning layer 5, via Al... a N layer 51, Al b In x Ga 1-b-x N layer 52, In 1-c Al c N-layer 53 and N-polarity Al d The GaN / N polar MgN superlattice layer 54 multilayer materials work together to reduce electron overflow while effectively increasing and accelerating hole injection, enhancing the conductivity and hole injection rate of the P-type layer 6, thereby effectively improving luminous efficiency.

[0028] In the potential barrier modulation layer 5, 0 < d < c < b < a < 1, 0 < x < 1 - c < 1, that is, Al a N layer 51, Al b In x Ga 1-b-x N layer 52, In 1-c Al c N-layer 53 and N-polarity Al d In GaN / N polar MgN superlattice layer 54, Al a Layer N (51) is a non-stoichiometric AlN material layer, with the Al content decreasing progressively between layers. b In x Ga 1-b-x N layer 52 and In 1-c Al c In layer N (53), the In content increases progressively. Decreasing the Al content effectively lowers the barrier height, while increasing the In content effectively lowers the barrier height. In barrier tuning layer 5, Al... a N layer 51, Al b In x Ga 1-b-x N layer 52, In 1-c Al c N-layer 53 and N-polarity Al d The interlayer barrier height of the GaN / N polar MgN superlattice layer 54 decreases with the decrease of Al content, thereby reducing electron overflow, lowering leakage channels, reducing the droop effect, reducing the energy required for hole injection, increasing hole injection, reducing the operating voltage, and further improving luminous efficiency.

[0029] In Al b In x Ga 1-b-x N layer 52 and In 1-c Al c In layer N, the In content increases layer by layer, while the Al content decreases layer by layer. b In x Ga 1-b-x N layer 52 and In 1-c Al c The barrier height of the N-layer 53 decreases step by step, and the lattice mismatch also decreases step by step, reducing the generation of defects and further improving the luminescence efficiency.

[0030] Among them, Al a N layer 51, Al b In x Ga 1-b-x N layer 52 and In 1-c Al cIn layer N, the Al content in each layer decreases along the epitaxial direction, with N being polar Al. d In the GaN / N polar MgN superlattice layer 54, the Al content increases along the epitaxial direction. The Al content in the barrier tuning layer 5 shows a slide-like change trend along the epitaxial direction, which first decreases and then increases slightly, in order to increase hole injection and improve hole injection efficiency.

[0031] Wherein, the Al a N layer 51, the Al b In x Ga 1-b-x N layer 52, the In 1-c Al c N layer 53 and the N polarity Al d In GaN / N polar MgN superlattice layer 54, the decrease in Al content between layers i is 0.01 < i ≤ 0.1;

[0032] The Al a N layer 51, Al b In x Ga 1-b-x N layer 52 and In 1-c Al c In layer N, the decrease in Al content in each layer is j, where j is 0 < j ≤ 0.01. The N-polar Al... d In GaN / N-polar MgN superlattice layers, the increment k of Al content is 0 < k ≤ 0.01. Changes in Al content cause changes in the potential barrier height. By controlling the decrease j / increase k of Al content in each layer to be less than the interlayer decrease i of Al content, a difference in the magnitude of Al content changes between interlayer and intralayer layers is created, forming electron traps, slowing electron movement, and reducing the drop effect. Furthermore, this makes the N-polar Al... d The increasing Al content in the GaN / N polar MgN superlattice layer creates a downward trend, which increases the hole migration speed and improves the hole injection efficiency.

[0033] Among them, Al a N layer 51, Al b In x Ga 1-b-x N layer 52 and In 1-c Al c The thickness of layer N53 decreases sequentially, and Al a The thickness of the N-layer 51 is 4nm to 5nm, Al b In x Ga 1-b-x The thickness of the N-layer 52 is 3nm to 4nm, In 1-c Al cThe thickness of the N-layer 53 is 2nm to 3nm, and the N-polarity is Al. d The thickness of the GaN / N polar MgN superlattice layer 54 is 2nm to 5nm, due to Al a N layer 51, Al b In x Ga 1-b-x N layer 52 and In 1-c Al c The thickness of the N-layer 53 decreases sequentially, and the lattice mismatch is continuously reduced, which indirectly releases stress. This makes the interface between layers smoother and flatter, reduces the generation of defects, and thus reduces leakage current, further improving luminous efficiency.

[0034] Among them, N polarity Al d The growth atmosphere of GaN / N-polar MgN superlattice layer 54 is N2 to ensure the formation of N-polar material layer.

[0035] Among them, N polarity Al d The GaN / N-polar MgN superlattice layer 54 includes periodically alternating N-polar Al... d The GaN sublayer 541 and the N-polar MgN sublayer 542 have a growth cycle of 3 to 5 cycles. Exemplarily, the growth cycle is 3, 4, or 5 cycles, but is not limited thereto. Preferably, the growth cycle is 3 cycles. The N-polar Al... d The thickness ratio between GaN sublayer 541 and N-polar MgN sublayer 542 is 1:1.

[0036] Among them, In 1-c Al c The growth pressure of N layer 53 is higher than that of Al. b In x Ga 1-b-x The growth pressure of layer 52 in N layer effectively prevents Al b In x Ga 1-b-x The In component in layer 52 during In growth 1-c Al c Diffusion occurs during the N-layer 53 process, further increasing the incorporation efficiency of the In component and improving the In... 1-c Al c The crystal quality of the N-layer further enhances the optoelectronic performance of the epitaxial structure.

[0037] This invention discloses a method for fabricating a gallium nitride light-emitting diode epitaxial structure, comprising:

[0038] S10. Provide substrate 1:

[0039] The substrate 1 can be any one of Si substrate, sapphire, SiC substrate or SiO2 substrate. Specifically, taking sapphire substrate as an example, the sapphire substrate 1 is placed in the MOCVD reaction chamber and treated with H2 and NH3 at a temperature of 1000℃~1150℃ for 14~15 minutes to prevent oxidation or contamination of the surface of the sapphire substrate 1.

[0040] S20. Buffer layer 2, N-type layer 3, multiple quantum well layer 4, barrier tuning layer 5 and P-type layer 6 are epitaxially grown sequentially on substrate 1.

[0041] Barrier layer 5 comprises Al deposited sequentially along the epitaxial direction a N layer 51, Al b In x Ga 1-b-x N layer 52, In 1-c Al c N-layer 53 and N-polarity Al d GaN / N polar MgN superlattice layer 54.

[0042] The specific steps of step S20 are as follows:

[0043] S21. Grow buffer layer 2 on substrate 1:

[0044] The buffer layer 2 is an AlN / GaN buffer layer. A high-temperature AlN two-dimensional nucleation layer is deposited on the substrate 1 by PVD sputtering, and then GaN buffer layer 2 is deposited in the MOCVD reaction chamber. The thickness of the buffer layer is 10nm to 30nm.

[0045] S22. Grow N-type layer 3 on buffer layer 2:

[0046] The N-type layer 3 is an N-type GaN layer, grown at a temperature of 1000℃~1150℃, with a thickness of 2µm~3µm and a Si doping concentration of 1.5×10⁻⁶. 18 cm -3 .

[0047] S23. Grow a multi-quantum-well layer 4 on the N-type layer 3:

[0048] The multi-quantum-well layer 4 comprises periodically alternating InGaN quantum well layers and GaN quantum barrier layers. The InGaN quantum well layers have a thickness of 1 nm to 4 nm, a growth temperature of 780 °C to 825 °C, a growth pressure of 200 torr to 250 torr, and a period of 8 to 10. The GaN quantum barrier layers have a thickness of 10 nm to 15 nm, a growth temperature of 780 °C to 820 °C, and a growth pressure of 200 torr to 250 torr.

[0049] S24. Growth of barrier tuning layer 5 on multi-quantum well layer 4:

[0050] Al was sequentially deposited on the multi-quantum-well layer 4. a N layer 51, Al b In x Ga 1-b-x N layer 52, In 1-c Al c N-layer 53 and N-polarity Al d GaN / N polar MgN superlattice layer 54, in which Al b In x Ga 1-b-x N layer 52, In 1-c Al c N-layer 53 and N-polarity Al d GaN / N polar MgN superlattice layers 54 can be grown using MOCVD or physical vapor deposition at temperatures ranging from 750℃ to 1010℃ and growth pressures ranging from 100 torr to 600 torr; Al a The N-layer 51 can be grown using molecular beam epitaxy or physical vapor deposition.

[0051] Among them, Al a The thickness of the N-layer 51 is 4nm to 5nm, Al b In x Ga 1-b-x The thickness of the N-layer 52 is 3nm to 4nm, In 1- c Al c The thickness of the N-layer 53 is 2nm to 3nm, and the N-polarity is Al. d The thickness of the GaN / N polar MgN superlattice layer 54 is 2nm to 5nm;

[0052] Among them, Al a N layer 51, Al b In x Ga 1-b-x N layer 52 and In 1-c Al c The growth atmosphere for layer 53 (N layer) is H2, and the N polarity is Al. d The growth atmosphere of GaN / N polar MgN superlattice layer 54 is N2;

[0053] During growth, control In 1-c Al c The growth pressure of N layer 53 is higher than that of Al. b In x Ga 1-b-x Growth pressure of layer 52 in N;

[0054] The flow rate of the Al source is controlled so that the Al content in each layer of the barrier layer 5 decreases by a margin of less than or equal to 0.1. a N layer 51, Al b In x Ga 1-b-x N layer 52 and In 1-c Al c In layer N, the Al content in each layer decreases along the epitaxial direction by an amount less than or equal to 0.01. N-polar Al d In the GaN / N polar MgN superlattice layer 54, the Al content increases along the epitaxial direction by an amount less than or equal to 0.01.

[0055] S25. Grow a P-type layer 6 on the barrier modulation layer 5:

[0056] Among them, the P-type layer 6 includes a P-type GaN layer and a P-type contact layer. The thickness of the P-type GaN layer is 15nm to 30nm, the growth temperature is 900℃ to 1000℃, and the reaction chamber pressure is 200 torr to 300 torr. The P-type contact layer is a GaN layer with a thickness of 1nm to 6nm and a Mg doping concentration of 1.0×10⁻⁶. 19 cm -3 ~3.0×10 20 cm -3 The growth temperature is 800℃~950℃.

[0057] This invention discloses an LED, including the gallium nitride light-emitting diode epitaxial structure described above.

[0058] The present invention will be further described below with reference to the accompanying drawings and embodiments:

[0059] Example 1

[0060] See Figure 1 As shown, this embodiment discloses a gallium nitride light-emitting diode epitaxial structure, including a substrate 1, a buffer layer 2, an N-type layer 3, a multiple quantum well layer 4, and a P-type layer 6 sequentially disposed thereon. A barrier modulation layer 5 is provided between the multiple quantum well layer 4 and the P-type layer 6. The barrier modulation layer 5 includes Al atoms sequentially deposited along the epitaxial direction. a N layer 51, Al b In x Ga 1-b-x N layer 52, In 1-c Al c N-layer 53 and N-polarity Al d GaN / N polar MgN superlattice layer 54.

[0061] In the barrier modulation layer 5, 0 < d < c < b < a < 1, 0 < x < 1 - c < 1, and the decrease in Al content between each layer is i = 0.1. In this embodiment, a decreases from 0.7 to 0.69, and x is 0.2.

[0062] Among them, Al a N layer 51, Al b In x Ga 1-b-x N layer 52 and In 1-c Al c In layer N (53), the Al content in each layer decreases along the epitaxial direction, with a decrease magnitude j of 0.01. N-polar Al d In the GaN / N polar MgN superlattice layer 54, the Al content increases along the epitaxial direction, with an increase rate k of 0.01.

[0063] Among them, Al a The thickness of the N-layer 51 is 5nm, Al b In x Ga 1-b-x The thickness of the N-layer 52 is 4nm, In 1-c Al c The thickness of the N-layer 53 is 3nm, and the N-polarity is Al. d The thickness of the GaN / N polar MgN superlattice layer 54 is 5 nm.

[0064] Among them, N polarity Al d The growth atmosphere for GaN / N polar MgN superlattice layer 54 is N2.

[0065] Among them, N polarity Al d The GaN / N-polar MgN superlattice layer 54 includes periodically alternating N-polar Al... d The growth cycle consists of three GaN sublayers and N-polar MgN sublayers.

[0066] Among them, In 1-c Al c The growth pressure of N layer 53 is higher than that of Al. b In x Ga 1-b-x Growth pressure of N layer 52.

[0067] See Figure 2 and Figure 3 As shown, the method for preparing the above-mentioned epitaxial structure includes:

[0068] S100. Provides a sapphire substrate 1;

[0069] S200. Buffer layer grown on substrate 1:

[0070] The buffer layer 2 is an AlN / GaN buffer layer. A high-temperature AlN two-dimensional nucleation layer is deposited on the substrate 1 by PVD sputtering, and then the GaN buffer layer is deposited in the MOCVD reaction chamber. The thickness of the buffer layer 2 is 15nm.

[0071] S300. Grow N-type layer 3 on buffer layer 2:

[0072] N-type layer 3 is an N-type GaN layer, grown at 1000℃, with a thickness of 2.5 μm and a Si doping concentration of 1.5 × 10⁻⁶. 18 cm -3 .

[0073] S400. Growth of a multi-quantum-well layer 4 on the N-type layer 3:

[0074] The multi-quantum-well layer 4 comprises periodically alternating InGaN quantum well layers and GaN quantum barrier layers. The InGaN quantum well layers have a thickness of 2.3 nm, a growth temperature of 825 °C, a growth pressure of 200 torr, and a period of 8. The GaN quantum barrier layers have a thickness of 12 nm, a growth temperature of 7820 °C, and a growth pressure of 200 torr.

[0075] See Figure 3 As shown, in S500, a barrier tuning layer 5 is grown on the multi-quantum well layer 4:

[0076] S510. Al deposition on multi-quantum-well layer 4 a N-layer 51 (using MBE), 5nm thick, growth atmosphere H2;

[0077] S520. In Al a Al was deposited on layer 51 of N. b In x Ga 1-b-x The N-layer is 52, the growth temperature is 900℃, the growth pressure is 200 torr, the thickness is 4nm, and the growth atmosphere is H2;

[0078] S530. In Al b In x Ga 1-b-x In deposited on layer 52 of N 1-c Al c The N-layer is 53, the growth temperature is 850℃, the growth pressure is 250 torr, the thickness is 3nm, and the growth atmosphere is H2;

[0079] S540. In In 1-c Al c N-polar Al was deposited on layer N53. dGaN / N polar MgN superlattice layer 54, grown at a temperature of 850℃, a growth pressure of 250 torr, a thickness of 5nm, and in an N2 atmosphere;

[0080] During growth, the Al source flux was controlled so that the Al content in each layer of the barrier modulation layer 5 decreased by 0.1 in increments. a N layer 51, Al b In x Ga 1-b-x N layer 52 and In 1-c Al c In layer N, the Al content in each layer decreases along the epitaxial direction by an increment of 0.01. The polar Al content in N is... d In the GaN / N polar MgN superlattice layer 54, the Al content increases along the epitaxial direction by an increment of 0.01.

[0081] S600. A P-type layer 6 is grown on the barrier modulation layer 5:

[0082] The P-type layer 6 comprises a P-type GaN layer and a P-type contact layer. The P-type GaN layer is 15 nm thick, grown at 900 °C, and grown at a reaction chamber pressure of 200 torr. The P-type contact layer is a GaN layer with a thickness of 2 nm and a Mg doping concentration of 3.0 × 10⁻⁶. 20 cm -3 The growth temperature is 900℃.

[0083] Example 2

[0084] This embodiment discloses a gallium nitride (GaN) light-emitting diode (LED) epitaxial structure, comprising a substrate, a buffer layer, an N-type layer, a multi-quantum-well layer, and a P-type layer sequentially disposed thereon. A barrier modulation layer is provided between the multi-quantum-well layer and the P-type layer, and the barrier modulation layer includes Al atoms sequentially deposited along the epitaxial direction. a N layer, Al b In x Ga 1-b-x N-layer, In 1-c Al c N-layer and N-polarity Al d GaN / N polar MgN superlattice layer.

[0085] In the barrier modulation layer, 0 < d < c < b < a < 1, 0 < x < 1 - c < 1, and the Al content decreases by 0.05 between each layer. In this embodiment, a decreases from 0.7 to 0.69, and x is 0.2.

[0086] Among them, Al a N layer, Al b In x Ga 1-b-x N layers and In1-c Al c In the N layers, the Al content in each layer decreases along the epitaxial direction, with a decrease magnitude j of 0.01. N-polar Al d In the GaN / N polar MgN superlattice layer, the Al content increases along the epitaxial direction, with an increase rate k of 0.01.

[0087] Among them, Al a The thickness of the N layer is 4 nm, Al b In x Ga 1-b-x The thickness of the N layer is 3nm, In 1-c Al c The thickness of the N layer is 2 nm, and the N-polarity is Al. d The thickness of the GaN / N polar MgN superlattice layer is 2 nm.

[0088] Among them, N polarity Al d The growth atmosphere for the GaN / N polar MgN superlattice layer is N2.

[0089] Among them, N polarity Al d The GaN / N-polar MgN superlattice layer includes periodically alternating N-polar Al atoms. d The growth cycle consists of three GaN sublayers and N-polar MgN sublayers.

[0090] Among them, In 1-c Al c The growth pressure of the N layer is higher than that of the Al layer. b In x Ga 1-b-x Growth pressure on the N-layer.

[0091] The method for preparing the above-mentioned epitaxial structure includes:

[0092] S100. Provides a sapphire substrate;

[0093] S200. Buffer layer grown on substrate:

[0094] The buffer layer is an AlN / GaN buffer layer. A high-temperature AlN two-dimensional nucleation layer is deposited on the substrate by PVD sputtering, and then the GaN buffer layer is deposited in the MOCVD reaction chamber. The thickness of the buffer layer is 15nm.

[0095] S300. Growing an N-type layer on the buffer layer:

[0096] The N-type layer is an N-type GaN layer, grown at a temperature of 1000℃, with a thickness of 2.5 μm and a Si doping concentration of 1.5 × 10⁻⁶. 18 cm -3 .

[0097] S400. Growth of multiple quantum well layers on N-type layers:

[0098] The multi-quantum-well layer comprises periodically alternating InGaN quantum well layers and GaN quantum barrier layers. The InGaN quantum well layers are 2.3 nm thick, grown at 825 °C, with a growth pressure of 200 torr, and have 8 periods. The GaN quantum barrier layers are 12 nm thick, grown at 7820 °C, and with a growth pressure of 200 torr.

[0099] S500. Growth of barrier tuning layers on multi-quantum-well layers:

[0100] S510. Depositing Al on a multi-quantum-well layer a The N-layer (using MBE) has a thickness of 4 nm and is grown in an H2 atmosphere.

[0101] S520. In Al a Al deposited on N layer b In x Ga 1-b-x N-layer, growth temperature 900℃, growth pressure 200 torr, thickness 3nm, growth atmosphere H2;

[0102] S530. In Al b In x Ga 1-b-x In deposited on layer N 1-c Al c N-layer, growth temperature 850℃, growth pressure 250 torr, thickness 2nm, growth atmosphere H2;

[0103] S540. In In 1-c Al c N-polar Al is deposited on the N layer. d GaN / N polar MgN superlattice layer, grown at a temperature of 850℃, a growth pressure of 250 torr, a thickness of 2nm, and in an N2 atmosphere;

[0104] During growth, the Al source flux is controlled so that the Al content in each layer of the barrier modulation layer decreases by 0.1 in increments. a N layer, Al b In x Ga 1-b-x N layers and In 1-c Al c In the N-layer, the Al content in each layer decreases along the epitaxial direction by an increment of 0.01, and the N-polar Al... d In the GaN / N polar MgN superlattice layer, the Al content increases along the epitaxial direction by an increment of 0.01.

[0105] S600. Growth of a P-type layer on a barrier tuning layer:

[0106] The P-type layer comprises a P-type GaN layer and a P-type contact layer. The P-type GaN layer is 15 nm thick, grown at 900 °C, and grown at a reaction chamber pressure of 200 torr. The P-type contact layer is a GaN layer with a thickness of 2 nm and a Mg doping concentration of 3.0 × 10⁻⁶. 20 cm -3 The growth temperature is 900℃.

[0107] Example 3

[0108] This embodiment discloses a gallium nitride (GaN) light-emitting diode (LED) epitaxial structure, comprising a substrate, a buffer layer, an N-type layer, a multi-quantum-well layer, and a P-type layer sequentially disposed thereon. A barrier modulation layer is provided between the multi-quantum-well layer and the P-type layer, and the barrier modulation layer includes Al atoms sequentially deposited along the epitaxial direction. a N layer, Al b In x Ga 1-b-x N-layer, In 1-c Al c N-layer and N-polarity Al d GaN / N polar MgN superlattice layer.

[0109] In the barrier modulation layer, d = c = b = a = 0.7, and x is 0.2.

[0110] Among them, Al a The thickness of the N layer is 5 nm, Al b In x Ga 1-b-x The thickness of the N layer is 4 nm, In 1-c Al c The thickness of the N layer is 3 nm, and the N-polarity is Al. d The thickness of the GaN / N polar MgN superlattice layer is 5 nm.

[0111] Among them, N polarity Al d The growth atmosphere for the GaN / N polar MgN superlattice layer is N2.

[0112] Among them, N polarity Al d The GaN / N-polar MgN superlattice layer includes periodically alternating N-polar Al atoms. d The growth cycle consists of three GaN sublayers and N-polar MgN sublayers.

[0113] Among them, In 1-c Al c The growth pressure of the N layer is higher than that of the Al layer. b In x Ga 1-b-x Growth pressure on the N-layer.

[0114] The method for preparing the above-mentioned epitaxial structure includes:

[0115] S100. Provides a sapphire substrate;

[0116] S200. Buffer layer grown on substrate:

[0117] The buffer layer is an AlN / GaN buffer layer. A high-temperature AlN two-dimensional nucleation layer is deposited on the substrate by PVD sputtering, and then the GaN buffer layer is deposited in the MOCVD reaction chamber. The thickness of the buffer layer is 15nm.

[0118] S300. Growing an N-type layer on the buffer layer:

[0119] The N-type layer is an N-type GaN layer, grown at a temperature of 1000℃, with a thickness of 2.5 μm and a Si doping concentration of 1.5 × 10⁻⁶. 18 cm -3 .

[0120] S400. Growth of multiple quantum well layers on N-type layers:

[0121] The multi-quantum-well layer comprises periodically alternating InGaN quantum well layers and GaN quantum barrier layers. The InGaN quantum well layers are 2.3 nm thick, grown at 825 °C, with a growth pressure of 200 torr, and have 8 periods. The GaN quantum barrier layers are 12 nm thick, grown at 7820 °C, and with a growth pressure of 200 torr.

[0122] S500. Growth of barrier tuning layers on multi-quantum-well layers:

[0123] S510. Depositing Al on a multi-quantum-well layer a The N-layer (using MBE) has a thickness of 5 nm and is grown in an H2 atmosphere.

[0124] S520. In Al a Al deposited on N layer b In x Ga 1-b-x N-layer, growth temperature 900℃, growth pressure 200 torr, thickness 4nm, growth atmosphere H2;

[0125] S530. In Al b In x Ga 1-b-x In deposited on layer N 1-c Al c N-layer, growth temperature 850℃, growth pressure 250 torr, thickness 3nm, growth atmosphere H2;

[0126] S540. In In 1-c Al c N-polar Al is deposited on the N layer. d GaN / N polar MgN superlattice layer, grown at a temperature of 850℃, a growth pressure of 250 torr, a thickness of 5nm, and in an N2 atmosphere;

[0127] S600. Growth of a P-type layer on a barrier tuning layer:

[0128] The P-type layer comprises a P-type GaN layer and a P-type contact layer. The P-type GaN layer is 15 nm thick, grown at 900 °C, and grown at a reaction chamber pressure of 200 torr. The P-type contact layer is a GaN layer with a thickness of 2 nm and a Mg doping concentration of 3.0 × 10⁻⁶. 20 cm -3 The growth temperature is 900℃.

[0129] Example 4

[0130] This embodiment discloses a gallium nitride (GaN) light-emitting diode (LED) epitaxial structure, comprising a substrate, a buffer layer, an N-type layer, a multi-quantum-well layer, and a P-type layer sequentially disposed thereon. A barrier modulation layer is provided between the multi-quantum-well layer and the P-type layer, and the barrier modulation layer includes Al atoms sequentially deposited along the epitaxial direction. a N layer, Al b In x Ga 1-b-x N-layer, In 1-c Al c N-layer and N-polarity Al d GaN / N polar MgN superlattice layer.

[0131] In the barrier modulation layer, 0 < d < c < b < a < 1, 0 < x < 1 - c < 1, and the decrease in Al content between layers is i = 0.1. In this embodiment, a decreases from 0.7 to 0.6, and x is 0.2.

[0132] Among them, Al a N layer, Al b In x Ga 1-b-x N layers and In 1-c Al c In the N layers, the Al content in each layer decreases along the epitaxial direction, with a decrease magnitude j of 0.1. N-polar Al d In the GaN / N polar MgN superlattice layer, the Al content increases along the epitaxial direction, with an increase rate k of 0.1.

[0133] Among them, Al a The thickness of the N layer is 5 nm, Al b In x Ga 1-b-xThe thickness of the N layer is 4 nm, In 1-c Al c The thickness of the N layer is 3 nm, and the N-polarity is Al. d The thickness of the GaN / N polar MgN superlattice layer is 5 nm.

[0134] Among them, N polarity Al d The growth atmosphere for the GaN / N polar MgN superlattice layer is N2.

[0135] Among them, N polarity Al d The GaN / N-polar MgN superlattice layer includes periodically alternating N-polar Al atoms. d The growth cycle consists of three GaN sublayers and N-polar MgN sublayers.

[0136] Among them, In 1-c Al c The growth pressure of the N layer is higher than that of the Al layer. b In x Ga 1-b-x Growth pressure on the N-layer.

[0137] The method for preparing the above-mentioned epitaxial structure includes:

[0138] S100. Provides a sapphire substrate;

[0139] S200. Buffer layer grown on substrate:

[0140] The buffer layer is an AlN / GaN buffer layer. A high-temperature AlN two-dimensional nucleation layer is deposited on the substrate by PVD sputtering, and then the GaN buffer layer is deposited in the MOCVD reaction chamber. The thickness of the buffer layer is 15nm.

[0141] S300. Growing an N-type layer on the buffer layer:

[0142] The N-type layer is an N-type GaN layer, grown at a temperature of 1000℃, with a thickness of 2.5 μm and a Si doping concentration of 1.5 × 10⁻⁶. 18 cm -3 .

[0143] S400. Growth of multiple quantum well layers on N-type layers:

[0144] The multi-quantum-well layer comprises periodically alternating InGaN quantum well layers and GaN quantum barrier layers. The InGaN quantum well layers are 2.3 nm thick, grown at 825 °C, with a growth pressure of 200 torr, and have 8 periods. The GaN quantum barrier layers are 12 nm thick, grown at 7820 °C, and with a growth pressure of 200 torr.

[0145] S500. Growth of barrier tuning layers on multi-quantum-well layers:

[0146] S510. Depositing Al on a multi-quantum-well layer a The N-layer (using MBE) has a thickness of 5 nm and is grown in an H2 atmosphere.

[0147] S520. In Al a Al deposited on N layer b In x Ga 1-b-x N-layer, growth temperature 900℃, growth pressure 200 torr, thickness 4nm, growth atmosphere H2;

[0148] S530. In Al b In x Ga 1-b-x In deposited on layer N 1-c Al c N-layer, growth temperature 850℃, growth pressure 250 torr, thickness 3nm, growth atmosphere H2;

[0149] S540. In In 1-c Al c N-polar Al is deposited on the N layer. d GaN / N polar MgN superlattice layer, grown at a temperature of 850℃, a growth pressure of 250 torr, a thickness of 5nm, and in an N2 atmosphere;

[0150] During growth, the Al source flux is controlled so that the Al content in each layer of the barrier modulation layer decreases by 0.1 in increments. a N layer, Al b In x Ga 1-b-x N layers and In 1-c Al c In the N-layer, the Al content in each layer decreases along the epitaxial direction by an increment of 0.01, and the N-polar Al... d In the GaN / N polar MgN superlattice layer, the Al content increases along the epitaxial direction by an increment of 0.01.

[0151] S600. Growth of a P-type layer on a barrier tuning layer:

[0152] The P-type layer comprises a P-type GaN layer and a P-type contact layer. The P-type GaN layer is 15 nm thick, grown at 900 °C, and grown at a reaction chamber pressure of 200 torr. The P-type contact layer is a GaN layer with a thickness of 2 nm and a Mg doping concentration of 3.0 × 10⁻⁶. 20 cm -3 The growth temperature is 900℃.

[0153] Comparative Example 1

[0154] The difference between this comparative example and Example 1 is that the barrier modulation layer of this comparative example does not include Al. a N layers, correspondingly, the preparation method does not include Al. a The steps for preparing the N-layer.

[0155] Comparative Example 2

[0156] The difference between this comparative example and Example 1 is that the barrier modulation layer of this comparative example does not include Al. b In x Ga 1-b- x N layers and In 1-c Al c N layers, correspondingly, the preparation method does not include Al. b In x Ga 1-b-x N layers and In 1-c Al c The steps for preparing the N-layer.

[0157] Comparative Example 3

[0158] The difference between this comparative example and Example 1 is that the barrier modulation layer of this comparative example does not include N-polar Al. d GaN / N-polar MgN superlattice layer, correspondingly, the preparation method does not include N-polar Al. d Preparation steps of GaN / N polar MgN superlattice layer.

[0159] Comparative Example 4

[0160] The difference between this comparative example and Example 1 is that there is no barrier tuning layer between the multi-quantum well layer and the P-type layer, but instead an electron blocking layer, which is P-AlGaN.

[0161] The luminous efficiency of the epitaxial wafers prepared by Examples 1-4 and Comparative Examples 1-4 was tested. The luminous efficiency measured by Examples 1-4 and Comparative Examples 1-3 was compared with the luminous efficiency measured by Comparative Example 4 to obtain the luminous efficiency improvement rate of Examples 1-4 and Comparative Examples 1-3. A positive luminous efficiency improvement rate indicates that the luminous efficiency of the experimental group is higher than that of Comparative Example 4, and a negative luminous efficiency improvement rate indicates that the luminous efficiency of the experimental group is lower than that of Comparative Example 4.

[0162] The results obtained are as follows:

[0163] Example 1 0.42 Example 2 0.36 Example 3 0.32 Example 4 0.33 Comparative Example 1 0.28 Comparative Example 2 0.26 Comparative Example 3 0.23

[0164] The experimental results show that, compared with comparative examples 1 to 3, the luminous efficiency of Examples 1 to 4 of the present invention is significantly improved, and Al a N layer, Alb In x Ga 1-b-x N-layer, In 1-c Al c N-layer and N-polarity Al d There is a synergistic effect between the GaN / N polar MgN superlattice multilayer material layers. Example 1 is superior to Example 3 and Example 4, indicating that the setting of the present invention, which makes the Al content variation range between layers and in layers different, can significantly improve the luminous efficiency.

[0165] The above description is merely a preferred embodiment of the present invention and is not intended to limit the present invention in any way. Although the present invention has been disclosed above with reference to preferred embodiments, it is not intended to limit the present invention. Any person skilled in the art can make some modifications or alterations to the above-described technical content to create equivalent embodiments without departing from the scope of the present invention. Any simple modifications, equivalent changes, and alterations made to the above embodiments based on the technical essence of the present invention without departing from the scope of the present invention shall still fall within the scope of the present invention.

Claims

1. A gallium nitride light-emitting diode epitaxial structure, comprising a substrate, a buffer layer, an N-type layer, a multiple quantum well layer, and a P-type layer sequentially disposed thereon, characterized in that, A barrier tuning layer is provided between the multi-quantum-well layer and the P-type layer. The barrier tuning layer comprises Al layers sequentially deposited along the epitaxial direction. a N layer, Al b In x Ga 1-b-x N-layer, In 1-c Al c N-layer and N-polarity Al d GaN / N polar MgN superlattice layer; The Al a N layers, the Al b In x Ga 1-b-x N layers and the In 1-c Al c In the N-layer, the Al content in each layer decreases along the epitaxial direction, and the N-polar Al... d In the GaN / N polar MgN superlattice layer, the Al content increases along the epitaxial direction.

2. The gallium nitride light-emitting diode epitaxial structure according to claim 1, characterized in that, In the barrier modulation layer, 0 < d < c < b < a < 1, 0 < x < 1 - c < 1.

3. The gallium nitride light-emitting diode epitaxial structure according to claim 1, characterized in that, The Al a N layers, the Al b In x Ga 1-b-x N layers, the In 1-c Al c N-layer and the N-polarity Al d In the GaN / N polar MgN superlattice layer, the decrease in Al content between layers, i, is 0.01 < i ≤ 0.1; The Al a N layers, the Al b In x Ga 1-b-x N layers and the In 1-c Al c In the N layers, the decrease in Al content in each layer is j such that 0 < j ≤ 0.01, and the N-polar Al... d In the GaN / N polar MgN superlattice layer, the increment of Al content k is 0 < k ≤ 0.

01.

4. The gallium nitride light-emitting diode epitaxial structure according to claim 1, characterized in that, The Al a N layers, the Al b In x Ga 1-b-x N layers and the In 1-c Al c The thickness of layer N decreases sequentially, and the Al a The thickness of the N layer is 4nm~5nm, and the Al b In x Ga 1-b-x The thickness of the N layer is 3nm~4nm, and the In 1-c Al c The thickness of the N layer is 2nm~3nm, and the N polar Al d The thickness of the GaN / N polar MgN superlattice layer is 2nm~5nm.

5. The gallium nitride light-emitting diode epitaxial structure according to claim 1, characterized in that, The N polarity Al d The growth atmosphere for the GaN / N polar MgN superlattice layer is N2.

6. The gallium nitride light-emitting diode epitaxial structure according to claim 1, characterized in that, The N polarity Al d The GaN / N-polar MgN superlattice layer includes periodically alternating N-polar Al atoms. d The growth cycle of GaN sublayer and N-polar MgN sublayer is 3 to 5.

7. The gallium nitride light-emitting diode epitaxial structure according to claim 1, characterized in that, The In 1-c Al c The growth pressure of the N layer is higher than that of the Al layer. b In x Ga 1-b-x Growth pressure on the N-layer.

8. A method for fabricating a gallium nitride light-emitting diode epitaxial structure, characterized in that, include: Provide substrate; A buffer layer, an N-type layer, a multiple quantum well layer, a barrier tuning layer, and a P-type layer are epitaxially grown sequentially on the substrate. The barrier conditioning layer comprises Al layers deposited sequentially along the epitaxial direction. a N layer, Al b In x Ga 1-b-x N-layer, In 1-c Al c N-layer and N-polarity Al d GaN / N polar MgN superlattice layer; The Al a N layers, the Al b In x Ga 1-b-x N layers and the In 1-c Al c In the N-layer, the Al content in each layer decreases along the epitaxial direction, and the N-polar Al... d In the GaN / N polar MgN superlattice layer, the Al content increases along the epitaxial direction.

9. An LED, characterized in that, Includes the gallium nitride light-emitting diode epitaxial structure according to any one of claims 1 to 7.

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