Research On Fabrication Of Nanoporous GaN And Recovery Of Damage To GaN Coursed By Dry Etching

According to the application of nanoporous GaN films as substrates in high quality GaN epitaxial growth, our study focuses on fabrication of nanoporous GaN films and the crystalline quality and optical property of this material. We also study about the damage to the surface of GaN films introduced by dry etching, and recover the damage by our new technique. Our work includes:(1) Fabrication of several-hundred-nanometer-thick AAO templates with uniform nanopore diameters and distribution by electron beam evaporation and electrochemical technique.(2) Research on fabrication of nanoporous GaN films by ICP etching using AAO templates as masks, especially on mechanism of ICP etching and the role of Cl₂/Ar mixed gas in ICP etching.(3) Compared with ordinary GaN films, crystal stress is released at a certain extent near boundaries of the nanopores, which has been proven by results of ultraviolet photoluminescence (UV-PL) spectra, Raman scattering spectrum and X-ray diffraction (XRD) spectra.(4) PL spectra and Hall mobility measurement indicate that ICP etching will introduce damages to GaN, leading to increase of surface roughness and deterioration of electrical and optical properties.(5) The deterioration of electrical and optical properties introduced by ICP etching can be alleviated by the combination of anneal at high temperature and nitrogen plasma treatment. It is more effective than recovery by only high temperature anneal or nitrogen...