Surface coarsening method of gallium nitride material layer

The invention discloses a surface coarsening method of a gallium nitride material layer. The method comprises the following steps: forming a mask layer on the upper surface of the gallium nitride material layer, wherein the mask layer is shaped by multiple cylinders dispersedly distributed on the upper surface of the gallium nitride material layer; and etching the upper surface by use of an etching gas through an inductively coupled plasma etching technology, wherein etching is continued for preset time after the mask layer is completely etched so as to respectively obtain basically hexagonal-pyramid-shaped projections at positions opposite to the multiple cylinders on the upper surface of the gallium nitride material layer. According to the invention, the regularly-shaped and uniformly distributed hexagonal-pyramid-shaped projections are obtained through coarsening the surface of the gallium nitride material layer by use of a dry etching method. The shape, the dimension and the period of the hexagonal-pyramid-shaped projections can be controlled, and the method is simple and is suitable for enhancing the luminescence efficiency of a GaN-based LED.