An Epitaxial Growth Method for Reducing Defect Density of Epitaxial Layer

Abstract

The invention provides an epitaxial growth method for reducing epitaxial layer defect density. According to the method, a u-GaN layer with the flat surface is obtained through the growth on a substrate. The method comprises the following steps that (1) a low-temperature GaN buffer layer is grown; (2) a layer of u-GaN is grown; (3) fused KOH or H3PO4 solution is used for corroding the u-GaN, and the surface dislocation is corroded for forming concave pits; (4) after the surface is cleaned, a layer of SiO2 is prepared, the SiO2 can be simultaneously deposited onto the plane u-GaN and in the corrosion concave pits until the surfaces of the corrosion concave pits are covered; (5) the SiO2 on the plane u-GaN is removed through being polishing and grinding, and only the SiO2 in the corrosion concave pits is left; (6) after the surface is cleaned, PECVD (plasma enhanced chemical vapor deposition) is continuously carried out for depositing the u-GaN, the u-GaN is continuously grown on the plane u-GaN, and can transversely span across the SiO2 at the corrosion concave pit part, and finally, the u-GaN layer with the flat surface is finally generated, and is used as the subsequent epitaxial growth basis. A GaN-based LED (light emitting diode) epitaxial wafer prepared by using the method provided by the invention has the advantages that the crystal quality is greatly improved, through the test, the dislocation density can be reduced to 106 / cm<2>, and the surface of the epitaxial layer is flat and has no defect.

Description

Technical field: [0001] The invention belongs to the technical field of LED epitaxial preparation, and in particular relates to an epitaxial growth method capable of reducing defect density of an epitaxial layer. Background technique: [0002] GaN-based optoelectronic devices have a wide range of applications due to their high thermal conductivity, high temperature resistance, radiation resistance, acid and alkali resistance, high strength and hardness, and wide band gap. Pure GaN substrate is currently the most suitable substrate material for growing epitaxy due to its good lattice matching with the epitaxial layer, but due to its high cost, heterogeneous substrates are often used. The lattice mismatch and thermal expansion mismatch coefficients of heterogeneous substrate materials and GaN are very large, and it is easy to cause large stress and high dislocation density during epitaxial growth, which will reduce carrier mobility, lifetime and material heat dissipation. Con...

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Problems solved by technology

However, the improvement of the crystal quality by the above methods is limited, and the dislocation density can only be reduced to 10 at most. 7 / cm 2

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