Dynamic Characteristics of AlGaN/GaN Fin-MISHEMTs With Al2O3 Dielectric

An extensive investigation of fabricated AlGaN/GaN fin-shaped metal-insulator-semiconductor high-electron-mobility transistors (Fin-MISHEMTs) with Al₂O₃ dielectric is presented in this paper. Based on the pulsed I-V measurements and numerical simulation, the dynamic characteristics of GaN-based Fin-MISHEMTs were carried out under various quiescent bias conditions and temperatures. Moreover, the physical mechanisms of current collapse and dynamic on-resistance increase induced by trapping effects were analyzed. The results show that the observed nonmonotonic variation of current collapse with the gate quiescent bias voltage is resulted from the combination of gate leakage injection-related and hot-electron injection-related trapping effects. Compared with the conventional planar MISHEMTs, the current collapse of AlGaN/GaN Fin-MISHEMTs is smaller due to lower gate leakage and smaller threshold voltage shift, which is benefited from its enhanced gate controllability. The current collapse and dynamic on-resistance increase of Fin-MISHEMTs can be further suppressed by optimizing the device structure, such as designing the fin channels only under the gate.