Fabrication of GaN suspended microstructures

We report on a versatile processing technology for the fabrication of micro -electromechanical systems in gallium nitride (GaN). This technology, which is an extension of photo-electrochemical etching, allows for the controlle d and rapid undercutting of p-GaN epilayers. The control is achieved throug h the use of opaque metal masks to prevent etching in designated areas, whi le the high lateral etch rates are achieved by biasing the sample relative to the solution. For GaN microchannel structures processed in this way, und ercutting rates in excess of 30 mum/min have been attained. We propose two mechanisms to account for these high etch rates. (C) 2001 American Institut e of Physics.