Piezoelectric actuation of all‐nitride MEMS

We present a MEMS technology based on (GaN/)AlGaN/GaN–heterostructures. Thereby the lower GaN layer represents the mechanical active layer, while the upper GaN and AlGaN layers supply the piezoelectrically active layers for actuation and the confinement of a 2D electron gas (at the lower interface). The 2DEG serves as back electrode for the piezoelectric actuation and as read–out, since it is modulated by the mechanical oscillation. The upper AlGaN and GaN layer both contribute to the total piezoelectric response, which was determined by piezoelectric force microscopy. The electrical field distribution throughout the heterostructure was determined by means of electroreflectance. (© 2008 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim)