Abstract: A p-GaN high-electron-mobility transistor (HEMT) includes a buffer layer stacked on a substrate, a channel layer stacked on the buffer layer, a supply layer stacked on the channel layer, a doped layer stacked on the supply layer, and a hydrogen barrier layer covering the supply layer and the doped layer. A source and a drain are electrically connected to the channel layer and the supply layer, respectively. A gate is located on the doped layer. The hydrogen barrier layer is doped with fluorine.

Abstract: A hybrid electrical power system for an electric vehicle, particularly an industrial electric vehicle such as an electric forklift, comprises a fuel cell stack, a DC/DC converter and a Li-ion battery. The DC/DC converter comprises a transformer for converting a voltage of direct current generated by the fuel cell stack to another voltage, and a controller for generating a reference voltage for the another voltage to approach. When the reference voltage is set to be larger than the another voltage, the fuel cell stack provides power to drive the vehicle and charge the Li-ion battery. When the reference voltage is set to be not larger than the voltage of direct current from the Li-ion battery, both the Li-ion battery and the fuel cell stack provide power to drive the vehicle.