GaN based high temperature strain gauges

Gallium Nitride based electronic devices have several unique properties such as robustness to high temperature, and both strong spontaneous and piezoelectric polarization fields. The polarization effects of Gallium Nitride are stable at high temperatures; therefore, it is an ideal material to fabricate high temperature strain gauges. In this work we have fabricated metal-insulator-semiconductor(MIS) capacitors to be used as a high temperature strain gauge. GaN based MIS capacitors were fabricated and tested both at room and high temperature. The gauge factor was measured to be 75 at room temperature. AlGaN/GaN heterostructures were also used to make MIS capacitors for testing at both room and high temperature. The gauge factors were measured on these devices to be 575 at room temperature, and 361 at 400 °C.