High-Temperature Electrical Transport Behavior of p-Doped Boron Diamond Film/n-WS2 Nanosheet Heterojunction

WS₂ is a promising material for applications in wearable devices, field-effect transistors, and high-performance heterojunctions. However, significant challenges remain regarding effective regulation and temperature stability. This study investigates the temperature-dependent electrical properties of WS₂ heterojunctions prepared by electrophoretic deposition on boron-doped diamond films. The results reveal that the rectification ratio of lightly doped boron heterojunctions at room temperature is 9.1, indicating thermal excitation behavior at temperatures above 100 °C. In contrast, heavily doped boron heterojunctions maintain a rectification ratio consistently below 1 over a temperature range from room temperature to 180 °C, indicating reverse rectification. The lowest rectification ratio observed at 140 °C is 0.17. Density functional theory (DFT) calculations suggest that hydrogen (H) termination generates an internal electric field in the opposite direction, causing a reversal of the rectification polarity, while oxygen (O) termination favors forward rectification. Additionally, due to vacancy defects in WS₂, the heterojunction exhibits negative differential resistance at 120 °C, with a peak-to-valley ratio of 2.4. Higher doping levels, in comparison to lower concentrations, offer a more stable rectification ratio at elevated temperatures, making the material more suitable for high-temperature, high-frequency, and high-power applications.