Study of the Temperature Dependence of AlGaN/GaN HEMTs with Oxygen Plasma Treatment

Abstract

The temperature‐dependent characteristics of AlGaN/GaN high electron mobility transistors (HEMTs) and recessed‐gate AlGaN/GaN HEMTs combined with oxygen plasma treatment (rec + oxy HEMTs) are investigated over a range from 25 to 300 °C. The peak transconductance and saturation current of both types of devices decrease with the increase of temperature due to the decline of channel electron mobility. It is interesting to find that the threshold voltage (VTH) exhibits a positive shift in the conventional HEMT, while a negative shift in the rec + oxy HEMT with temperature increases. The increase in gate leakage current with the temperature is dominated by tunneling mechanism. Furthermore, the annealing process of 300 and 400 °C for 2 min in N2 ambient are utilized in these two kinds of devices for further estimation, respectively. It is found that the channel mobility can be recovered after the 400 °C annealing process, but the VTH shows an obvious negative shift in rec + oxy HEMTs.