Postprocessing annealing effects on direct current and microwave performance of AlGaN/GaN high electron mobility transistors

The effects of postprocessing annealing on direct current, radio frequency small signal, and power performances of AlGaN/GaN high electron mobility transistors with a gate-length of 0.2 μm were investigated. The postannealing technique can improve the device performance, especially, after 10 min postannealing at 400 °C, the gate-to-drain breakdown voltage of devices exhibits remarkable improvement from 25 to 187 V. The maximum extrinsic transconductance increases from 223 to 233 mS/mm at a drain bias of 10 V after 10 min annealing at 400 °C. The maximum drain current at a gate bias of 1 V increases from 823 to 956 mA/mm. After annealing, the values of the unity current gain cut-off frequency and the maximum oscillation frequency increases from 24 and 80 GHz to 55 and 150 GHz, respectively. The output power and gain at 10 GHz were improved from 16.4 dBm and 11.4 dB to 25.9 dBm and 19 dB, respectively.