A computationally efficient modelling methodology for field-plates in GaN HEMTs

Multiple field-plates (FP) are employed in typical GaN HEMTs for improving the device performance. In industry standard models, FP regions are modelled by adopting a full HEMT device model. As a result, a GaN HEMT device with two field plates requires the computation of equations which are the equivalent of three HEMT devices; one for the channel region, and two for the field-plate regions. This causes computational inefficiency. In this paper, we present a simplified field-plate modelling methodology which reduces the computational expense through means of approximations whilst maintaining an excellent degree of accuracy. Using insights from TCAD simulations, we develop simplifications for modelling the FP regions, improving the overall model speed. The developed methodology is validated against the TCAD data showing excellent accuracy and significant model speed improvement over the industry standard model.