AlGaN/GaN heterostructure field-effect transistor model including thermal effects

A new AlGaN/GaN heterostructure field-effect transistor (HFET) model, in th e framework of the gradual channel approximation and based on Monte Carlo s imulations of the electron transport properties, is presented, The effects on the de HFET output characteristics arising from contact resistances, fro m the ungated access channels between the gate and the source and between t he gate and the drain, and from self-heating are analyzed. By examining the channel potential, the ungated regions are shown to have nonlinear charact eristics. The solution method uses implicit analytical relationships for th e current in the gated and ungated segments of the channel that are connect ed hy matching boundary conditions. Thermal effects on the transport parame ters associated with self-heating are included self-consistently. The model results are In very good agreement with experimental data from AlGaN/GaN H FETs fabricated on sapphire substrates. The model also identifies several d evice design parameters that need to be adjusted to obtain optimized perfor mance in terms of output current and transconductance.