Material structure for improving ohmic contact of p-GaN film and preparation method thereof

Abstract

The invention discloses a material structure for improving the ohmic contact of a p-GaN film and a preparation method thereof, wherein the material structure comprises a substrate (1), a buffer layer (2), an n-GaN film layer (3), a p-GaN film layer (4) and a heavily-doped p-GaN film layer (5), wherein the buffer layer (2) grows on the substrate (1); the n-GaN film layer (3) grows on the buffer layer (2); the p-GaN film layer (4) grows on the n-GaN film layer (3); and the heavily-doped p-GaN film layer (5) grows on the p-GaN film layer (4). According to the invention, the thin heavily-doped p-GaN layer with a large number of defects is inserted between the p-GaN film and a metal, and the heavily-doped p-GaN layer is enabled to have a large number of defect-energy levels by the methods of low-temperature growth or ion injection and the like, so that the transportation of current carriers can be finished through variable-range hopping or defect-energy level assistance, and furthermore, the specific contact resistivity of the p-GaN film and the contacted metal can be decreased, and the ohmic-contact performance of the p-GaN film is improved.

Description

technical field [0001] The invention relates to the technical field of semiconductors, in particular to a material structure for improving the ohmic contact of a p-GaN thin film and a preparation method thereof. Background technique [0002] Gallium nitride (GaN) is a third-generation semiconductor material with a wide band gap. It is a series of materials composed of indium and aluminum (including aluminum nitride, aluminum gallium nitride, indium gallium nitride, indium nitride, aluminum indium gallium nitride ) is widely used in light-emitting diodes (LEDs), blue lasers (Blue Lasers), solar cells and ultraviolet detection due to its large band gap, wide spectral range (covering the entire range from ultraviolet to infrared), high temperature resistance and corrosion resistance. It has important application value in the fields of optoelectronics and microelectronics such as devices. [0003] At present, people can use molecular beam epitaxy (MBE) and metal organic chemica...

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Problems solved by technology

[0005] Due to the large forbidden band width of the P-GaN film, no metal work function can meet the requirements of forming an ohmic contact with it, and the hole concentration of p-GaN cannot be further increased (the maximum is about 1×10 18 cm -3 ), which leads to the fact that the ohmic contact of p-GaN film cannot simply achieve low contact resistance

[0006] At present, the commonly used methods to improve the ohmic contact of p-GaN include rapid thermal annealing, multi-layer metal and other methods. These methods improve the ohmic contact from the aspects of contact metal and subsequent treatment, but do not take advantage of the properties of the p-GaN film itself Ohmic contact for low contact resistance

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