Physical Characteristics of Low-Dose Nitrogen Ions-Implanted Copper Oxide Thin Film on n-Si (100) Substrate

Thin film of copper oxide was deposited onto a silicon substrate through DC magnetron sputtering system. Nitrogen ions (N⁺) were implanted into the film using Pelletron Accelerator at different doses (5 × 10¹², 5 × 10¹³ and 5 × 10¹⁴ ions/cm²) while maintaining a constant ion energy of 300 keV. The X-ray diffraction study revealed a diffraction peak of CuO (− 111) in all the samples. The crystallite size of CuO decreased at 5 × 10¹² ions/cm² and then increased with the dose up to 5 × 10¹⁴ ions/cm². The decrease in crystallite size was attributed to structural disorder in the film caused by ions irradiation, while at relatively higher doses (> 5 × 10¹² ions/cm²), localized thermal effects improved the structural ordering of the material through the annihilation of defects. The surface morphology of the film showed a decrease in its grain size at 5 × 10¹² ions/cm², followed by an increase with a further increase in the ion dose. N⁺ implantation at 5 × 10¹² ions/cm² decreased the surface roughness of CuO, while the roughness remained constant at the higher doses. The electrical resistivity of CuO decreased upon N⁺ implantation at 5 × 10¹² ions/cm² and then increased with a further increase in the ion dose. The band gap of the CuO exhibited a similar trend to that of its resistivity and crystallite size. These findings show that the N⁺ implantation serves as an effective method for tuning the physical properties of the copper oxide film, for its superior performance in the electronic and optoelectronic devices.