Piezoelectric GaN sensor structures

Free-standing GaN and AlGaN/GaN cantilevers have been fabricated on (111) silicon substrate using dry etching. On these cantilevers, a piezoresistor and a high-electron-mobility transistor (HEMT) structure have been realized, and the piezoresponse has been characterized. Cantilever bending experiments resulted in a Young's modulus of approximately 250 GPa, a sensitivity of K similar to 90,and a modulation of the HEMT current of up to 50%. It is seen that the piezoresponse could be related to both the bulk properties and the properties of the heterostructure interface.