FABRICATION OF GAN NANOSTRUCTURES BY A SIDEWALL-ETCHBACK PROCESS

GaN structures as small as 300 angstrom have been fabricated using conventional optical lithography by employing a deposition/selective etchback technique. After initial resist patterning conformal plasma-enhanced chemical vapour deposition or reactive sputtering of a metal (W or WSi(x)) or a low temperature dielectric (SiN(x) or SiO2) is followed by an anisotropic etchback to leave a thin sidewall on the resist feature. The resist is then removed by dry etching, leaving the sidewall, which can be used as a mask for subsequent pattern transfer into the underlying GaN. Electron cyclotron resonance dry etching in CH4/H2/Ar discharges is shown to produce GaN nanostructures without any change in the near-surface stoichiometry of the material.