High-temperature electrical performances and physics-based analysis of p-GaN HEMT device

High-temperature electrical performances of enhancement-mode (E-mode) high electron mobility transistor with p-type Gallium Nitride (GaN) gate cap are evaluated here. The physics-based mechanisms behind the behaviours are also analysed by the simulations and analytical models. For static electrical performances, the changes of GaN bandgap and the interface states or traps are considered to be influential factors for the little variations of threshold voltage (V-T). Meanwhile, the on-state resistance increases and trans-conductance decreases at high temperatures due to the reduction in electron mobility (mu(eff)). As for blocking characteristic, high temperature-induced increase of leakage current may result from multi-reasons, such as the increase of intrinsic carrier concentration and lowering of trap barrier. In addition, a segmental method is presented to understand the gate leakage current at high temperatures. For capacitance characteristics, the increase of channel resistance makes the measured gate capacitance lower than the intrinsic value. For dynamic electrical performances, the high temperature-induced decrease of mu(eff) leads to the increase of plateau voltage, bringing the decreases of total switching time and total switching energy loss, which are quite different from those of the devices with traditional metal-oxide-semiconductor structures.