Physics-based Compact Modeling of MSM-2DEG GaN-based Varactors for THz Applications

In this paper, we present a physics based compact model for GaN-based Metal-Semiconductor-Metal (MSM) 2DEG varactors in which the intrinsic charges and currents are evaluated in terms of the bias-dependent surface-potential. Physical phenomena such as Thermionic Emission, Poole-Frenkel Effect and Fowler-Nordheim Tunneling are incorporated to realize the non-idealities of the Schottky gates. The model is successfully validated against measured data for a state-of-the-art GaN-based varactor. Furthermore, a circuit simulation is performed for a phase shifting network wherein its behavior for various bias conditions and operating frequencies is observed using the proposed model.