Monte Carlo Transport Studies of GaN High Electron Mobility Transistors (HEMTs) for Microwave Applications

摘要

Calculations of the electronic mobility and drift velocity have been carried out for bulk GaN and AlGaN-GaN heterojunctions based on a Monte Carlo approach. Very good agreement with available experiments has been obtained, and the calculations yielded a set of best-fit transport parameters. The calculations were then extended for the large-signal nonlinear response characteristics of HEMTs with particular emphasis on inter-modulation distortion (lMD). The results demonstrated an optimal operating point for low lMD at reasonably large output power due to a minima in the lMD curve. An increase in dynamic range with temperature has been predicted, due to a relative suppression of interface roughness scattering. The results indicate Increasing the mole fraction for the barrier layer, reducing the transit length, and introducing a thin AIN interfacial layer for suppressing real space transfer performance enhancements. Simulations were also carried Out to probe possible enhancements in Gun effect oscillators, it has been shown that repetitive structures with serial segments to fashion a 'multiple domain' device could lead to significant improvements in Output power over conventional, single-transit structure, and so such multiple IaN diodes merit serious experimental study. Monte Carlo studies of GaN HEMTs also probed the effects of scattering due to edge dislocations strains. For self-consistency, numerical solution of Schrodinger, Poisson, and charge balance equations were used for the eigen-functions. Electron mobilities predictions around 1.711 x 10(3) cm2/Vs, are in close agreement with reported data. At the highest dislocation density of 10(10) cm-2, mobility reductions of 16.8 percent and 8.6 percent are predicted for 77 K and 300 K, respectively.