Mg-doped p-GaN, which cannot be etched and porosified by wet etching, is annealed in a N-2 environment to fabricate porous p-GaN for the first time. In the annealing temperature range of 900-1150 degrees C, the pore size and pore density increase with the annealing temperature rising. The porous p-GaN with a V-shape pore structure obtained at 1050 degrees C presents the best crystal quality. We demonstrate that the formation of porous structures is largely due to the decomposition of GaN molecules located at the defects in the p-GaN epitaxial film. Porous p-GaN epitaxial wafers can be used to prepare violet light photodetectors. Compared with the as-grown sample, the porous GaN obtained at 1050 degrees C exhibits faster carrier mobility, higher light response speed, lower surface state density and similar visible light transmittance. Our work will promote the development of porous p-type GaN materials.
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