DC & RF characteristics of normally-off AIN/GaN MOSHEMT by varying oxide thickness

In this paper a unique AlN/GaN MOSHEMT (Metal Oxide Semiconductor High Electron Mobility Transistor) structure is reported with ultra-thin AlN barrier layer with thickness 2nm which is less than the critical thickness, so that 2-Dimensional Electron Gas (2DEG) formation is not held at zero gate bias. Suitable positive gate bias is applied for creating 2DEG at the heterointerface which leads the device to operate in normally-off or enhancement mode which is the novelty of this work. DC and RF performance of this MOSHEMT are investigated by considering 10nm and 20nm thick oxide layer. The MOSHEMT with oxide thickness of 10nm gives a positive threshold voltage of 3V and can be operated in enhancement mode for power electronics applications whereas the device having oxide thickness of 20nm gives maximum frequency of oscillation of 35GHz and can be used in RF applications.