Comprehensive performance analysis of diamond Schottky diodes with argon-ion-modified oxygen-terminated surfaces

Oxygen termination on diamond surfaces plays a critical role in determining the performance of diamond-based electronic and biosensing devices. However, limited insights into oxygen-terminated diamond surfaces have constrained further performance improvements. To bridge this gap, the current study developed a novel oxidation methodology, which enhanced both oxygen coverage and device performance. Current-voltage (I–V) and capacitance-voltage (C–V) measurements confirmed improved electrical characteristics. X-ray photoelectron spectroscopy (XPS) revealed increased oxygen coverage and reconstruction of the oxygen-terminated surfaces. Kelvin probe force microscopy (KPFM) verified the homogenous surface potential distribution following oxidation. The presence of acceptor interface states was further confirmed using KPFM under dark and ultraviolet illumination. Additionally, density functional theory (DFT) calculations provided theoretical support for the observed surface reconstruction and performance enhancement. Overall, the I–V, C–V, XPS, KPFM, and DFT analysis collectively establish correlations between oxygen termination composition, interface states, and Schottky barrier diode performance, offering new pathways for the optimization of diamond-based devices.