Post-annealing effects on trapping behaviors in AdGaN/GaN HEMTs

Trapping effects in AlGaN/GaN high-electron mobility transistors (HEMTs) are investigated using dynamic current-voltage (I-V) measurements with different quiescent biases and pulse widths to examine post-annealing effects after Schottky gate formation. The results show that trapping/detrapping phenomena by traps with emission/capture time constants of shorter than 10 mu s are dominant in non-annealed devices. The devices annealed at 400 degrees C for 10 minutes in a furnace exhibit significantly smaller current dispersion and have a smaller number of traps. However, after post-annealing, a small number of traps with a time constant of longer than 10 mu s are created or activated. Further annealing at 400 degrees C leads to increase in current dispersion, indicating that more traps with an emission time constant > 10 mu s are created. These traps induced by post-annealing are responsible for the trapping effects when pulse width >= 10 mu s. (c) 2005 WILEY-VCH Verlag GmbH & Co.