High performance AlGaN/GaN pressure sensor with a Wheatstone bridge circuit

Abstract

In this work, by taking into account the isotropic piezoelectric property of III-nitrides and the stress distribution in the circular diaphragm, AlGaN/GaN pressure sensor with a specially designed Wheatstone bridge structure is demonstrated. Two pairs of gateless HEMTs are placed at the tensile (near to the edge) and compressive (in the center) stress regions of the circular diaphragm, respectively, to maximize the pressure sensor's responsivity and stability. As a result, the 2DEG resistors located diagonally featured completely opposite piezoelectric polarization effects, which translated to a linear response of the fabricated AlGaN/GaN pressure sensor with a high sensitivity of 72 μV/kPa/V. The device also showed a large output capability of 64.8 mV/V, suggesting a potentially low power consumption in the practical applications.