Oxygen-plasma-induced Cu2O MSM photodetector derived from metallic Cu thin film for UV sensing

초록

Copper oxide (Cu2O) has emerged as a promising p-type semiconductor for optoelectronic applications owing to its direct bandgap, cost-effectiveness, and environmental stability. In this study, we synthesized Cu2O thin films using an oxygen-plasma treatment (OPT) and investigated their structural, optical, and electrical properties for ultraviolet (UV) photodetection. The oxidation process was precisely controlled by varying the bottom radio-frequency (RF) power (200-300 W) to optimize the phase composition and defect states. Grazing-incidence x-ray diffraction and x-ray photoelectron spectroscopy confirmed the formation of phase-pure Cu2O at a moderate RF power, while a higher RF power promoted CuO formation owing to excessive oxidation. Optical analysis revealed increased transmittance and a slight narrowing of the optical bandgap (2.87-2.80 eV) with increasing RF power, attributed to reduced oxygen vacancies and strain effects. Cu2O-based metal-semiconductor-metal photodetectors exhibited a reduced dark current and stable photocurrent response under 360 and 400 nm illumination, consistent with the material-bandgap characteristics. These findings demonstrate that OPT enables the precise tuning of Cu2O properties, making it a viable material for next-generation UV photodetectors with enhanced performance and stability.

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