Modelling and optimization of GaN capped HEMTs

Abstract

The effect of GaN cap and its thickness on device performance is investigated using simulations by Silvaco Atlas toolbox. The simulations are based on meticulous calibration of a conventional, lateral, GaN capped, 1μm gate-length HEMT with a source-to-gate and gate-to-drain spacings of 2μm, and 3μm, respectively. The breakdown voltage of the GaN HEMT is improved by the aid of p-doped GaN cap and field plates to BV=630V showing an improvement of 540V in comparison to an unoptimized device. Furthermore, the possible creation of two dimensional hole gas (2DHG) at the interface of GaN cap and AlGaN barrier and its effect on the device behaviour is studied.