GaN based MEMS accelerometer for high temperature application

Inertial sensing technologies in high temperature environments over 500°C are in great demand in aerospace, power plants and material processing applications. However, conventional micro-electromechanical systems (MEMS) sensors still cannot be operated at such high temperature area and need to be isolated in controlled environments. Gallium nitride (GaN) is very promising for high power devices, high temperature electronics and microsystems due to their wide energy bandgap with low intrinsic carrier density at high temperature over 500°C. Capacitive inertial sensors which consist of two separated electrodes can be operated by detecting capacitance changes between the electrodes upon applied stress. Capacitive inertial sensors have lower thermal drift, high resolution and good noise performance compare to peizoresistive sensors. In this study, we present a design of MEMS accelerometer using GaN as structure layer, grown epitaxially on aluminum nitride/silicon substrate. The resonance frequency of the designed accelerometer shows 2.235 kHz and bandwidth is around 1.2 kHz. Modeling and simulation results of the GaN accelerometer will be discussed and characterization of the fabricated devices would be presented.