HIGHLY ANISOTROPIC PHOTOENHANCED WET ETCHING OF N-TYPE GAN

A room-temperature photoelectrochemical etching process for n-type GaN films using a 0.04 M KOH solution and Hg arc lamp illumination is des cribed. The process provides highly anisotropic etch profiles and high etch rates (>300 nm/min) at moderate light intensities (50 mW/cm(2) @ 365 nm). The etch rate and photocurrent are characterized as a functio n of light intensity for stirred and unstirred solutions, and the etch process is found to be diffusion limited for light intensities greate r than 20 mW/cm(2) @365 nm. A reaction mechanism for the etch process is proposed. (C) 1997 American Institute of Physics.