Structural, optical, and electrical characterizations of Cr-doped CuO thin films

The polycrystalline copper oxide (CuO) thin films have been produced using the method of spin coating on the soda–lime glass (SLG) as well as the substrate of p-type Si (1 0 0) wafers at 500 °C in furnace. The obtained undoped and Cr-doped thin films of CuO have been comprehensively characterized via X-ray diffraction (XRD), ultraviolet–vis (UV–Vis) spectroscopy, the current–voltage ( I – V ), and capacitance–voltage ( C – V ) characteristics for providing information on quality of the crystalline nature, change in energy band gap and electrical properties, respectively. Structural analysis results obtained from XRD data demonstrate that CuO films in conjunction with Cr doping indicated that all thin films have monoclinic polycrystalline nature, with two main peaks of (− 111) and (111) with d hkl of about 2.52 and 2.32 Å, respectively. The transmittance and energy band gap values of undoped and Cr-doped thin films of CuO ranging in varying concentration ratio have been determined in the wavelength region of 300–1100 nm. The highest value has been found to be around 33% related to 3% Cr doping in the visible range. UV–Vis spectrum analysis results indicate that both transmittance value and energy band gap value of the CuO films are changed with the increase in Cr doping ratio in CuO solution at room temperature. The band gap energy was determined to be between 1.67 and 2.03 eV with the increase in Cr concentration. The I – V and C – V characteristics of Cr:CuO/p-Si diodes were associated with the CuO/p-Si diodes. Although the best rectification ratio ( RR ) is seen in the 1% Cr-doped diode ( RR = 2.33 × 10 3 for ± 1 V), other diodes also have significant rectification behavior. It is seen that doping of Cr had a significant change on the obtained devices’ performance. Thus, the Cr:CuO/p-Si diodes generated by 1% Cr doping using spin coating method had the highest light sensitivity compared with those of the other diodes.