Diamond/SnO₂ Heterojunction p-n Diodes With Ion/off of 10⁸ and Breakdown Voltage Over 400 V

The deep level of n-type donors for diamond limits the development of diamond-based electronics, including bipolar transistors, junction field effect transistors, etc. In this study, vertical diamond/SnO₂ p-n heterojunction diodes were fabricated. The SnO2 was deposited by electron beam evaporation and its conductivity was tuned by post-annealing process. The electrical characteristics of diamond/SnO₂ p-n diodes annealed at 400°C and 500°C were investigated. The p-n diodes have a good rectifying ratio of 10⁸, and the maximum breakdown voltage is over 400V. XPS results confirm the presence of C-Sn bond at the SnO2/diamond interface after post-annealing, which is speculated to be the key mechanism for the formation of heterojunction. The proposed diamond/SnO2 heterostructure can promote the application of diamond-based power devices for electronic and heterogeneous integration circuits.