This work reports the bias and pressure sensitivity of AlGaN/GaN High Electron Mobility Transistors (HEMTs) sensing elements strategically placed on a pressure sensitive diaphragm clamped at its edges. The sensitivity was over 150 times greater in the weak inversion regime than in the strong inversion regime of the HEMT, leading to a drain current change of >38% when a pressure of 50 bar was applied. The sensitivity of the HEMT to pressure followed an exponential dependence from atmospheric pressure up to 80 bar, behaviour explained by the response of the density of a two-dimensional electron gas to pressure induced changes in the HEMT threshold voltage in the weak inversion regime. Finally, it was found that the sensitivity of the HEMT was maximum when it was situated in the middle of the diaphragm, whereas a device mounted over the clamping point showed less than 0.02% change in drain current when pressure change of 50 bar was applied.
Le Boulbar, E. D., Edwards, M. J., Vittoz, S., Vanko, G., Brinkfeldt, K., Rufer, L., Johander, P., Lalinský, T., Bowen, C. R., & Allsopp, D. W. E. (2013). Effect of bias conditions on pressure sensors based on AlGaN/GaN High Electron Mobility Transistor. Sensors and Actuators A-Physical, 194, 247-251. https://doi.org/10.1016/j.sna.2013.02.017