Combined Effects of Proton Irradiation and Forward Gate-Bias Stress on the Interface Traps in AlGaN/GaN Heterostructure

The combined effects of proton irradiation and forward gate-bias stress on the interface traps of AlGaN/GaN heterostructure have been studied in this article. It is found that the effect of proton irradiation and forward gate-bias on the shift of flat band voltage
$V_{\mathrm {FB}}$
is independent. By utilizing the frequency-dependent conductance technique, it is found that the trap density
$D_{\mathrm {T}}$
at metal/AlGaN interface decreases after proton irradiation and the
$D_{\mathrm {T}}$
at most energy levels increases after the following forward gate-bias. The
$D_{\mathrm {T}}$
at AlGaN/GaN interface increases after proton irradiation and then decreases after the following forward gate-bias. The energy level range of metal/AlGaN interface traps reduces significantly under the forward gate-bias for the irradiated devices, however, that of AlGaN/GaN interface traps decreases little. In summary, the combined effect of proton irradiation and forward gate-bias stress on the interface traps is more complex than that on the bulk traps in AlGaN layer.