Fabrication of Large-Area Suspended MEMS Structures Using GaN-on-Si Platform

In this letter, piezosensitive elements featuring large-size suspended gallium nitride (GaN) microstructures are fabricated with a two-step dry-release technique using the GaN-on-Si platform. The suspended microstructures are integrated with highly piezosensitive AlGaN/GaN heterostructures as sensing units to realize the GaN-based integrated microsensors. To characterize the residual-stress distribution of the fabricated microstructures, micro-Raman spectroscopy is employed. A microaccelerometer structure with a 250 times 250-mum
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proof-mass area is fabricated with the proposed fabrication technique, and the piezoresponse properties of the integrated sensing elements are characterized through bending experiment.