Effect of fluorine interface redistribution on performance of AlGaN/GaN HEMTs

The effect of fluorine interface redistribution on dc and microwave performances of SF6 plasma-treated AlGaN/GaN high-electron mobility transistors (HEMTs) was investigated. Selective SF6 plasma treatment of the AlGaN/GaN HEMT gate interface yielded increases in the current gain cut-off frequency (fT) and maximum frequency of oscillation (fmax) of almost 60%. Annealing induced fluorine interface redistribution showed a low impact on the electron drift mobility and a negligible impact on the peak transconductance of the HEMTs. A large impact of the fluorine interface redistribution was observed for the threshold voltage and sheet carrier concentration of two-dimensional electron gas (2DEG). Consequently, it led to a decrease in the fT and fmax values, but the values were still higher than those of conventional reference HEMTs.