Studies on electron beam evaporated ZrO ₂/AlGaN/GaN metal-oxide-semiconductor high-electron-mobility transistors

Metal-oxide-semiconductor high-electron-mobility transistors were demonstrated on AlGaN/GaN with electron beam (EB) evaporated ZrO ₂. The composition of the EB deposited ZrO ₂ thin films was confirmed using X-ray photoelectron spectroscopy (XPS). The fabricated ZrO ₂-based MOSHEMTs exhibited high positive gate voltage of operation up to +7 V with low gate leakage current. For a comparison, conventional high-electron-mobility transistors (HEMTs) were also fabricated with identical device dimensions. The maximum drain current densities of 1168 and 538 mA/mm were observed on MOSHEMTs and HEMTs, respectively. Low gate leakage current density of four orders of magnitude was observed on ZrO ₂-based MOSHEMTs when compared with the conventional HEMTs. The observation of high forward on-voltage with low gate leakage current density and high positive operational voltage reveals the importance of ZrO ₂ dielectric films for MOSHEMT devices.