Influence of temperature on the sensitivity of the AlGaN/GaN C-HEMT-based piezoelectric pressure sensor

We present a finite element method (FEM) analysis of the AlGaN/GaN diaphragm-based pressure sensor with integrated C-HEMT. Our concept uses the C-HEMT as a vertical ring gate capacitor to sense the changes in the piezoelectric charge generated while pressure loading. The lattice mismatch and different thermal expansion coefficients in manufacturing process put the diaphragm to the tension. The operating conditions, especially the elevated temperature, may cause the mechanical stress variations and therefore also the change in mechanical behavior of the pressure sensing diaphragm. Therefore we performed the FEM simulation to predict the influence of elevated temperature and to determine the operating temperature range of proposed circular diaphragm-based MEMS pressure sensor.