In this work, we present a pressure sensor based on diamond coated AlGaN/GaN diaphragm with integrated high electron mobility transistor (HEMT). The influence of the diamond film thickness (in the range of 1 μm to 50 μm) on the properties of the AlGaN/GaN diaphragm is studied by finite element simulation method (FEM). The effect of thermal buckling as well as the induced piezoelectric charge of HEMTs as a function of pressure and temperature is investigated. It was found out that diamond coated sensor better prevents the effect known as thermal buckling of the diaphragm at elevated temperature. Thermal buckling of diaphragms with 1, 5, 10 μm diamond coating occurs at temperature 40, 73 and 142 °C, respectively. Compared with original GaN diaphragm, diamond expanded the operational temperature range of the pressure sensor. Moreover, compared with the operational range of pressure sensor based on pure GaN diaphragm (up to 30 kPa), diamond coated modified MEMS sensors withstand relatively higher pressures (2.2 MPa). The maximum load on the diaphragm increased two times by adding only 1 μm of diamond coating.

Date Published: 21 May 2015
PDF: 7 pages
Proc. SPIE 9517, Smart Sensors, Actuators, and MEMS VII; and Cyber Physical Systems, 95171I (21 May 2015); doi: 10.1117/12.2179126

Published in SPIE Proceedings Vol. 9517:
Smart Sensors, Actuators, and MEMS VII; and Cyber Physical Systems
José Luis Sánchez-Rojas; Riccardo Brama, Editor(s)