High Temperature Characterization of III-Nitride Pressure Sensors

High-temperature pressure sensors are critical for aerospace, automotive, food and chemical processing, and petroleum industries [1], [2]. Conventional Si piezoresistive sensors degrade above $150^{\circ} \mathrm{C}$ due to their thermal carrier generation properties and leakage currents, limiting their applicability. [1], [2] In this work, we investigated our novel AlGaN/GaN HFET-based MEMS pressure sensors, which utilize the higher bandgap and piezoresistivity of the two-dimensional electron gas (2DEG) at the AlGaN/GaN heterojunction to address this application gap at elevated temperatures. Sensor performance was investigated for 35 kPa change in pressure, both theoretically and experimentally. A good correlation between theoretical and experimental resistance changes ($\Delta \mathrm{R}_{\mathrm{DS}} / \mathrm{R}_{\mathrm{DS}}$) and Gauge Factors (GF) was observed. Furthermore, stable and repeatable sensor operation was demonstrated up to $250^{\circ} \mathrm{C}$, surpassing prior higher temperature performance of III-Nitride and Si based pressure sensors. [2], [3]