Modeling of AlGaN/GaN HEMT based stress sensors

GaN based devices show great potential for high power, high frequency and extreme-environment applications. Due to spontaneous and piezoelectric polarization properties, these devices are also suitable for pressure monitoring or detection of biomolecules causing surface stress. Therefore, GaN based monolithic sensor system can be applied for the detection of biomolecules or pressure imaging for biomedical applications, sensor data processing and transmission of the sensor data even in extreme environmental conditions. This paper investigates the analytical performance of GaN high electron mobility transistor (HEMT) device for the induced strain due to external pressure and surface stress. Analytical expressions for the conductance-stress behavior of the sensor have been developed. The change in two-dimensional electron gas density at the heterointerface of AlGaN/GaN layers resulting from the change in polarizations causes change in the output current of the device. The effects of both the tensile and the compressive strains due to the external force have been studied. This model can be effectively applied to the measurement of target force and to the detection of polar or nonpolar biomolecules.