Post‐annealing effects on trapping behaviors in AlGaN/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 µs are dominant in non‐annealed devices. The devices annealed at 400 °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 µs are created or activated. Further annealing at 400 °C leads to increase in current dispersion, indicating that more traps with an emission time constant >10 ms are created. These traps induced by post‐annealing are responsible for the trapping effects when pulse width ≥10 µs. (© 2005 WILEY‐VCH Verlag GmbH & Co. KGaA, Weinheim)