Pressure sensors based on AlGaN/GaN High Electron Mobility Transistor: An investigation of electricalparameters influences to response sensitivity
Résumé
Nowadays, it is well known that GaN or III-V based pressure sensors are suitable for high-temperature and harsh environment applications. Along the years, researchers used different devices to turn pressure solicitation into readable and sensitive signal. Basic resistor was used in the early studies to demonstrate the proof of sensor concept. Since, the integration of High Electron Mobility Transistor (HEMT) structure sensing element has shown an increase of sensitivity could be achieved because of HEMT device. Many paper showed electrical parameters played a key role in the improvements of sensitivity, and especially the gate bias. However, none of them deeply investigate the role of each parameter on the sensitivity. In this work, we screened the sensitivity of MOCVD-grown AlGaN/GaN HEMT as sensing element disposed on a sapphire membrane for pressure sensors purpose. We investigated with a particular emphasis, the response sensitivity under static pressure for different HEMT working regime: (1) strong, (2) moderate and (3) weak inversion regimes (see fig. 1). We discussed the possible hypothesis - i.e IDS behaviour in different regime, polarization and band structure modification - that lead the sensor to be more sensitive in the weak inversion regime. Radial response of the chip was investigated measuring sensitivity on 6 sensing elements placed along the chip. Finally, the pressure dependency of the sensor was investigated from atmospheric to 80 bar in 10 bar step pressure.