Characterization of GaN Cantilevers Fabricated with Deep-Release Techniques

摘要

Gallium nitride (GaN) and related wide-bandgap materials have found successful applications in a wide range of devices such as optoelectronic devices and high-power microwave amplifiers; GaN-based microelectro mechanical system (MEMS) devices are also drawing more attentions because of the materials’ superior properties. To implement GaN-based integrated sensors,suspended GaN microstructure integrated with piezosensitive AlGaN/GaN high electron mobility transistor (HEMT) is a strong candidate. In this article, integrated AlGaN/GaN cantilevers on (111) silicon substrate are fabricated and characterized. The process started with AlGaN/GaN HEMTs fabrication followed by a series of dry-etch-only MEMS process. To characterize the residual stress distribution, Micro-Raman spectroscopy is used and the residual stress in suspended GaN cantilever is found ～ 90% lower after releasing. A type of micro-bending test is used to characterize the piezoresponse of AlGaN/GaN HEMT on the GaN cantilever. An output current modulation greater than 20% can be observed when the cantilever is vertically downward deflected ～ 30 μm.