RF Power performance of passivated ALGAN/GAN hfets grown on sic and sapphire

We have analysed the impact of SiN surface passivation on the performance of undoped (piezo) AlGaN/GaN HFETs grown on SiC and sapphire. Though there is little change after passivation in carrier concentration and mobility as evidenced by Hall measurements the RF power performance is significantly improved leading to state of the art power densities of up to 6.5 Watt/mm at 10GHz and absolute power of 6.6 Watt cw for a 1.2mm piezo device on SiC substrate

Monte Carlo simulations of AlGaN/GaN heterojunction field-effect transistors (HFETs)

Self-consistent Monte Carlo simulations are reported for AlGaN/GaN HFETs. Hot-carrier scattering rates are determined by fitting experimental ionization coefficients and the doping character of the GaN is obtained from substrate bias measurements. Preliminary simulations for a simple model of the AlGaN surface are described and results are found to be consistent with experimental data. The high-frequency response of short-gate-length transistors is found to be sensitive to the charge state of the free AlGaN surface and it is proposed that current-slump phenomena may also be related to deep levels at this surface. Breakdown calculations show interesting two-dimensional effects close to the drain contact