Modeling of GaN/AlN heterostructure-based nano pressure sensors

We quantify the influence of thermopiezoelectric effects in nano-sized Al[subscript x]Ga[subscript 1-x]N/GaN heterostructures for pressure sensor applications based on the barrier height modulation principle. We use a fully coupled thermoelectromechanical formulation, consisting of balance equations for heat transfer, electrostatics and mechanical field. To estimate the vertical transport current in the heterostructures, we have developed a multi-physics model incorporating thermionic emission, thermionic field emission, and tunneling as the current transport mechanisms. A wide range of thermal (0-300 K) and pressure (0-10 GPa) loadings has been considered. The results for the thermopiezoelectric modulation of the barrier height in these heterostructures have been obtained and optimized. The calculated current shows a linear decrease with increasing pressure. The linearity in pressure response suggests that Al[subscript x]Ga[subscript 1-x]N/GaN heterostructure-based devices are promising candidates for pressure sensor applications under severe environmental conditions.