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±0.45×10−3pF∕μm as a function of the radius of the membrane at a fixed pressure of +9.5bar and exhibits a linear characteristic response between −0.5 and +1bar with a sensitivity of 0.86pF∕bar for a 600μm 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.

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