LED epitaxial wafer structure for improving luminous efficiency

Abstract

The application discloses an LED epitaxial wafer structure for improving light emitting efficiency, which comprises a substrate, an AlN buffer layer, an undoped GaN layer, an n-type GaN layer doped with Si, a multi-quantum well layer, an AlGaN electron blocking layer and a P-type GaN layer in sequence, wherein the multi-quantum well layer comprises 9-14 periodic composite structures of InGaN well layer / GaN barrier layer / InN layer, the InN layer is used for compensating In component of a quantum well interface, improving crystal quality of a well-barrier interface in the quantum well, Si is doped in the GaN barrier layer, the Si doping concentration in each GaN barrier layer is 0.8-0.9 times of the Si doping concentration in the previous GaN barrier layer, the Si doping concentration in the GaN barrier layer is gradually reduced, the electron transverse expansion capability is improved, and the electron and hole recombination efficiency in the quantum well is improved. The application can effectively improve the light emitting efficiency of the LED.

Description

Technical Field

[0001] This invention relates to the field of semiconductor technology, and more specifically, to an LED epitaxial wafer structure for improving luminous efficiency. Background Technology

[0002] A light-emitting diode (LED) is a semiconductor electronic device that converts electrical energy into light energy. When current flows through an LED, electrons and holes recombine within its multiple quantum wells, emitting monochromatic light. As a highly efficient, environmentally friendly, and green solid-state lighting source, LEDs offer advantages such as low voltage, low energy consumption, small size, light weight, long lifespan, high reliability, and rich colors. Currently, the scale of domestic LED production is gradually expanding. With the increasingly widespread application of LEDs, the market demand for their brightness is also increasing, especially for high-end LED chip products such as deep ultraviolet LEDs, mobile phone / TV backlight chips, and mini / micro-LEDs, whose luminous efficiency needs to be improved as soon as possible.

[0003] Existing LED epitaxial multi-quantum-well layers are InGaN well / GaN barrier layer structures. The recombination efficiency of electrons and holes in the quantum wells is not high, and the crystal quality of the multi-quantum-well layers is not high, which seriously hinders the improvement of LED luminous efficiency. Summary of the Invention

[0004] The purpose of this invention is to provide an LED epitaxial wafer structure that improves luminous efficiency. By inserting a very thin InN layer after the InGaN quantum well layer, the crystal quality of the well-barrier interface in the quantum well is improved, while the Si doping concentration of the GaN barrier layer is gradually reduced to improve the lateral expansion capability of electrons, improve the recombination efficiency of electrons and holes in the quantum well, and effectively improve the luminous efficiency of the LED.

[0005] The LED epitaxial wafer structure for improving luminous efficiency disclosed in this application comprises, in sequence, a substrate, an AlN buffer layer, an undoped GaN layer, a Si-doped n-type GaN layer, a multiple quantum well layer, an AlGaN electron blocking layer, and a p-type GaN layer. Its key feature is that the multiple quantum well layer comprises a composite structure of 9 to 14 periodically arranged InGaN well layers / InN layers / GaN barriers. The InN layers compensate for the In composition at the quantum well interface, improving the crystal quality of the well-barrier interface within the quantum wells.

[0006] Furthermore, the GaN barrier layer is doped with Si, and the Si doping concentration in each GaN barrier layer is 0.8 to 0.9 times that in the previous GaN barrier layer. By controlling the gradual decrease of the Si doping concentration in the GaN barrier layer, the lateral expansion capability of electrons is improved, and the recombination efficiency of electrons and holes in the quantum well is increased.

[0007] Optionally, the thickness of the InN layer is 0.1–1 nm, and the growth time of the InN layer is 8–15 s.

[0008] Optionally, the Si doping concentration of the GaN barrier layer ranges from 1E17 to 1E18 cm⁻¹. -3 .

[0009] Compared with the prior art, the LED epitaxial wafer structure provided by the present invention achieves at least the following beneficial effects:

[0010] In the traditional quantum well InGaN well layer / GaN barrier layer growth process, the increase in growth temperature causes In to precipitate in the InGaN well layer, resulting in a deterioration of the quantum well interface. This invention compensates for the In composition of the quantum well interface by inserting a very thin InN layer after the quantum well InGaN layer, thereby improving the crystal quality of the well-barrier interface in the quantum well.

[0011] In traditional LED epitaxial quantum well structures, doping the quantum barrier with Si causes the valence band to bend downwards, increasing the hole-blocking barrier height. Consequently, the injection efficiency of holes from the p-type side into the quantum wells decreases further, potentially concentrating only in the quantum well closest to the p-type layer. This leads to a severe asymmetry in the distribution of electrons and holes, hindering electron-hole recombination luminescence. This invention, by designing a graded Si barrier layer and controlling the gradual reduction of Si doping concentration in the GaN barrier layer, better adjusts the carrier distribution within the multi-quantum-well region. This promotes electron-hole recombination, enhances the lateral expansion capability of electrons, and improves the carrier recombination efficiency within the quantum wells, thereby increasing the LED's luminous efficiency and effectively reducing its operating voltage.

[0012] Other features and advantages of the invention will become clear from the following detailed description of exemplary embodiments of the invention with reference to the accompanying drawings. Attached Figure Description

[0013] The accompanying drawings, which are incorporated in and form part of this specification, illustrate embodiments of the invention and, together with their description, serve to explain the principles of the invention.

[0014] Figure 1 The figure shown is a complete cross-sectional schematic diagram of the LED epitaxial wafer provided in the embodiment of this application;

[0015] Among them, 1. Sapphire substrate, 2. AlN buffer layer, 3. Undoped GaN layer, 4. Si-doped n-type GaN layer, 5. Multiple quantum well layer, 6. AlGaN electron blocking layer, 7. P-type GaN layer, 51. InGaN well layer, 52. InN layer, 53. GaN barrier layer-1, 54. GaN barrier layer-2. Detailed Implementation

[0016] Traditional InGaN well / GaN barrier layer LED epitaxial multi-quantum-well layer structures suffer from low electron-hole recombination efficiency within the quantum wells and low crystal quality of the multi-quantum-well layers, severely hindering the improvement of LED luminous efficiency.

[0017] To improve the luminous efficiency of LEDs, this invention proposes an LED epitaxial wafer structure to enhance luminous efficiency, such as... Figure 1 As shown, the layers are arranged in sequence as follows: substrate 1, AlN buffer layer 2, undoped GaN layer 3, Si-doped n-type GaN layer 4, multiple quantum well layer 5, AlGaN electron blocking layer 6, P-type GaN layer 7, InGaN well layer 51, InN layer 52, GaN barrier layer-1 (labeled 53), and GaN barrier layer-2 (labeled 54).

[0018] First, using a metal-organic chemical vapor deposition (MOCVD) reactor, an AlN buffer layer 2, an undoped GaN layer 3, a Si-doped n-type GaN layer 4, and an InGaN well layer 51 are sequentially grown on a substrate. Then, an InN layer 52 with a thickness of 0.1-1 nm is grown on the surface of the InGaN well layer 51 for 8-15 s. The InN layer 52 compensates for the In composition at the quantum well interface, improving the crystal quality of the well-barrier interface in the quantum well. Next, a Si-doped GaN barrier layer-1 is grown on the InN layer 52. Then, the InGaN well layer 51 and InN layer 52 are grown, followed by a Si-doped GaN barrier layer-2. The Si doping concentration in the GaN-2 barrier layer is 0.8-0.9 times that in the GaN barrier layer-153. A composite structure of InGaN well layers / GaN barrier layers / InN layers is repeatedly grown, with a total number of 9-14 InGaN well layer / GaN barrier layer / InN layer composite structures. These 9-14 InGaN well layer / GaN barrier layer / InN layer composite structures together form a multi-quantum well layer 5. The Si doping concentration in the GaN barrier layer ranges from 1E17 to 1E18 cm⁻¹. -3 The Si doping concentration in each GaN barrier layer is 0.8 to 0.9 times that in the previous GaN barrier layer. By controlling the gradual decrease of Si doping concentration in the GaN barrier layers, the lateral electron expansion capability is improved, thereby increasing the electron-hole recombination efficiency in the quantum well. Finally, an AlGaN electron blocking layer 6 and a P-type GaN layer 7 are grown on the multi-quantum-well layer 5.

[0019] While specific embodiments of the invention have been described in detail by way of examples, those skilled in the art should understand that the examples are for illustrative purposes only and not intended to limit the scope of the invention. Those skilled in the art should understand that modifications can be made to the above embodiments without departing from the scope and spirit of the invention. The scope of the invention is defined by the appended claims.

Claims

1. An LED epitaxial wafer structure for improving luminous efficiency, comprising, in sequence, a substrate, an AlN buffer layer, an undoped GaN layer, a Si-doped n-type GaN layer, a multiple quantum well layer, an AlGaN electron blocking layer, and a p-type GaN layer, characterized in that: The multi-quantum well layer comprises a composite structure of 9-14 periodically arranged InGaN well layers / InN layers / GaN barrier layers. The InN layers compensate for the In composition at the quantum well interface, improving the crystal quality of the well-barrier interface in the quantum well. The GaN barrier layers are doped with Si, and the Si doping concentration in each GaN barrier layer is 0.8-0.9 times that in the previous GaN barrier layer. By controlling the gradual decrease of the Si doping concentration in the GaN barrier layers, the lateral expansion capability of electrons is improved, thereby increasing the electron-hole recombination efficiency in the quantum well.

2. The LED epitaxial wafer structure for improving luminous efficiency according to claim 1, characterized in that, The InN layer has a thickness of 0.1~1nm and a growth time of 8~15s.

3. The LED epitaxial wafer structure for improving luminous efficiency according to claim 1, characterized in that, The Si doping concentration of the GaN barrier layer ranges from 1E17 to 1E18 cm⁻¹ -3 .

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