Development of gallium nitride-based MEMS structures

The fabrication of MEMS structures has generally depended on the ability to carry out highly selective, deep lateral and vertical etching of the component materials. This is particularly problematic in gallium nitride (GaN) and the associated AlGaN and InGaN materials, which are all noted for their chemical inertness. We report here a method for producing MEMS in this material system based on backside-illuminated photoelectrochemical (BIPEC) undercut wet etching. We also discuss resonance spectra of structures fabricated by this method, including cantilevers and membranes.