p-type GaN epitaxial wafer with high ohmic contact features and preparation method thereof

Abstract

The present invention provides a p-type GaN epitaxial wafer with high ohmic contact features and a preparation method thereof. The preparation method comprises the steps of: the step 1: preparing a substrate (10); the step 2: performing epitaxial growth of an Mg-doped GaN layer on the substrate (10); the step 3: performing annealing for the Mg-doped GaN layer to activate a magnesium acceptor in the Mg-doped GaN layer to convert the Mg-doped GaN layer to a p-type GaN epitaxial layer (11); and the step (4): performing epitaxial growth of a p++-type GaN cover layer (12) on the p-type GaN epitaxial layer (11). The heavily-doped p++-type GaN cover layer is grown on the p-type GaN layer, and the heavily-doped p++-type GaN cover layer does not perform high-temperature annealing to improve the quality of the ohmic contact layer of the epitaxial wafer and reduce the specific contact resistance rate of the contact of the p-type material and the metal.

Description

technical field [0001] The present disclosure relates to the technical field of semiconductor devices, in particular to a p-type GaN epitaxial wafer with high ohmic contact characteristics and a preparation method thereof. Background technique [0002] GaN-based materials are also known as Group III nitride materials (including InN, GaN, AlN, InGaN, AlGaN, etc., and their forbidden band width ranges from 0.7-6.2eV), and their spectra cover the near-infrared to deep ultraviolet bands. The third-generation semiconductor after Si and GaAs has important application value in the field of optoelectronics. In the 1990s, with the development of the two-step growth method and the p-type annealing activation method, GaN-based materials and devices have received extensive attention. At present, GaN-based lasers have been successfully applied to laser lighting, laser projection, laser TV, industrial processing and other fields. However, compared with GaAs, InP and other materials, GaN-...

AI Technical Summary

Problems solved by technology

At present, GaN-based lasers have been successfully applied to laser lighting, laser projection, laser TV, industrial processing and other fields. However, compared with GaAs, InP and other materials, GaN-based lasers still have problems such as low photoelectric conversion efficiency and short life. Type GaN-based materials are related to the high ohmic contact resistance of the metal, resulting in high voltage and severe heat generation

The main reasons for the difficulty in realizing the ohmic contact of p-type GaN-based materials are: (1) there is no suitable metal material with a work function greater than that of p-type GaN; (2) p-type GaN itself has high resistivity and low hole concentration, so it is difficult to realize an effective tunneling

In the prior art, high-temperature annealing is required to activate the Mg impurities in the p-type material after the growth of the epitaxial wafer is completed. The high-temperature annealing temperature generally adopts a temperature of 600°C-900°C. At this time, many defects will be generated and the p-type characteristics will be deteriorated.

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