A compact model of AlGaN/GaN HEMTs power transistors based on a surface-potential approach

In this paper we present a compact model for Al
_x
Ga
_1-x
N/GaN High Electron Mobility Transistors (HEMTs) developed for circuit simulation of power transistors. A physical approach is followed and drain current and intrinsic node charges are calculated using the surface-potential formalism. The HSP model (acronym for HEMT Surface-Potential model) presented here includes: dependence on the aluminum content of the energy band-gap and of the spontaneous and piezoelectric polarizations, incomplete donor activation, temperature dependence of different parameters and self-heating effect. Moreover, a physical self-heating model including heat diffusion from channel to substrates of different thermal conductivities is implemented. Other effects, like series resistances, velocity saturation and channel length modulation -which are important when the HEMT transistor works at high voltage and high current- are also incorporated in the model.