Simulation of Self-Heating and Bulk Trapping Effects on Drain Current Static and Transient Characteristics of AlGaN/GaN HEMTs

Numerical device simulation studies of selfheating, buffer and barrier layer trapping effects on drain current characteristics of AlGaN/GaN high-electron mobility transistors (HEMTs) are carried out under static and dynamic operation modes. In simulation model, a buffer layer trap at E_C-0.5 eV, a barrier layer trap at E_C-0.45 eV, and self-heating effects are considered. The simulation results are validated with the measured data. The changes in the I_D-V_D and I_D-V_G characteristics at different trap concentrations (10¹⁶-10¹⁸ cm^-3) are predicted. The drain-lag turn-on transient simulations are performed to study the dynamic performance of the HEMTs. The self-heating effect on the drain current transient response is analyzed. To estimate the time constant of the trapping phenomena, transient characteristics are simulated by excluding self-heating effects. Similarly, the effect of trap density (10¹⁶-10¹⁸ cm^-3) on the transient response is reported and also transient characteristics are obtained at different trap energies (E_C-0.1 eV to E_C-1.0 eV). Simulation results reveal that the drop in the drain current under transient is mainly caused due to the channel temperature rise, whereas the magnitude of the transient current is affected by the buffer trap concentration.