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. • Normally-off diamond transistor is designed with n-ZnO/p-diamond heterojunction gate. • The recessed gate structure is effective to modulate the threshold voltage. • The current distribution layer is adopted to boost the electrical performance. • The operation mechanism of the HJFET is investigated extensively.