MoO3 Doping Effects on the Performance of CuO High-Temperature Current Rectifiers

Herein, CuO thin films were thermally evaporated onto n-Si and doped with MoO₃ (MCO-xx, where xx denotes the dopant wt.%). XRD confirmed a monoclinic CuO phase for all films, while MoO₃ incorporation strongly modified the microstructure: 0.5 wt.% produced a marked increase in crystallite size with a substantial reduction in microstrain, stacking faults, and line-defect density, whereas higher dopant levels partially reintroduced lattice distortion. The resulting n-Si/p-CuO rectifiers exhibited high, bias-dependent rectification ratios, reaching 109 and 5600 at 1.5 and 5.0 V for the undoped device, respectively, and increasing by about fourfold at 1.5 V for 1.5 wt.% doping. Current–voltage characteristics measured over 298–373 K revealed a progressive reduction of rectification with temperature while preserving rectifying behavior up to 373 K. Transport analysis indicates that thermionic emission and thermally assisted tunneling govern conduction at room temperature; MoO₃​ doping lowers the effective barrier height and reduces the tunneling width, whereas increasing temperature increases the extracted barrier height. These findings demonstrate that MoO₃-modified CuO/Si interfaces can deliver low-voltage rectification with sustained operation at elevated temperature.