Normally-off n-ZnO/p-diamond heterojunction field effect transistor with recessed gate and current distribution layer

In this paper, an n-ZnO/p-diamond heterojunction field effect transistor (HJ-FET) with recessed gate and current distribution layer is designed and optimized by using TCAD software. It demonstrates that the threshold voltage and breakdown voltage can be remarkably affected by the doping concentration and thickness of both n-ZnO and p-diamond. Additionally, the threshold voltage can be further enhanced by introducing a recessed gate due to the enhanced depletion capacity on the channel layer. Although the conduction modulation by the enhanced electric field decreases the on-resistance, the obviously decreased breakdown voltage by the recessed gate degrades the electrical performances. Finally, a current distribution layer between source and drain electrodes is added to decrease the on-resistance of diamond HJ-FET. After optimizing the parameters, the diamond HJ-FET exhibits a larger threshold voltage, a smaller on-resistance and a higher breakdown voltage.