Capacitance pressure sensor based on GaN high-electron-mobility transistor-on-Si membrane

The changes in the capacitance of the channel of an AlGaN/GaN high-electron-mobility transistor (HEMT) membrane structure fabricated on a Si substrate were measured during the application of both tensile and compressive strain through changes in the ambient pressure. The capacitance of the channel displays a change of 7.19 +/- 0.45 x 10(-3) pF/mu m m as a function of the radius of the membrane at a fixed pressure of + 9.5 bar and exhibits a linear characteristic response between -0.5 and + 1 bar with a sensitivity of 0.86 pF/bar for a 600 m m radius membrane. The hysteresis was 0.4% in the linear range. These AlGaN/GaN HEMT membrane-based sensors appear to be promising for both room-temperature and elevated-temperature pressure-sensing applications. (c) 2005 American Institute of Physics.