High performance metal-semiconductor-metal visible photodetectors with sulfurization process of CuO and Cu2O thin films

In this study, thin films of CuO and Cu2O semiconductors were grown on n-type Si (100) and glass substrates by DC magnetron sputtering method in a controlled manner. X-ray Diffraction (XRD) measurements have confirmed that only CuO and Cu2O phases appeared in the respected films. The bandgap values for the CuO and Cu2O thin films are 2.05 and 2.64 eV, respectively, as confirmed by absorption measurements, respectively. When considering photodetector performances, CuO-based thin film has exhibited better responsivity and photosensitivity (Iph/Id) values, with 0.33 A/W and 516 %, respectively. To further improve the photodetector performances, the CuO and Cu2O thin films were sulfurized for 30 min. The sulfurization process has shown that grain boundaries are reduced, and crystal sizes have increased in materials by converting CuO to CuSO4 and Cu2O to Cu2S with minor CuS phases. The bandgaps of the samples have exhibited a reduction, 1.90 eV for CuSO4, and 2.25 eV for Cu2S. Electrical tests on photodetectors have revealed that sulfurized materials have reduced dark current, increased photosensitivity by up to 743 % with larger detectivity for Cu2S sample. Furthermore, improvements in ideality factors and rectification ratios indicate that device performance is significantly improved by sulfurization. In conclusion, the sulfurization process has demonstrated significant improvements in the performance of CuO-based photodetectors by enhancing the responsivity and photosensitivity, making them more efficient for practical applications. © 2025