Influence of Treatment Time on the Synthesis of Copper Oxide Semiconductor Films by Cathode Cage Plasma Deposition

Due to its elemental abundance, nontoxic nature, and suitable optical-electrical properties, copper oxide is a valuable p-type semiconductor for photovoltaic (PV) applications. However, synthesizing copper oxide films for PV devices with a band gap close to the Shockley–Queisser limit (1.4 eV) using a one-step deposition process is important for maximum efficiency and synthesis simplification. In this work, cathodic cage plasma deposition (CCPD) of copper oxide (CuO + Cu₂O) films on glass was performed to evaluate the microstructural, morphological, chemical, and band gap changes as a function of treatment time (2 h, 3 h, 4 h, and 5 h). The samples were analyzed by scanning electron microscopy, energy-dispersive spectroscopy, x-ray diffraction, and Raman spectroscopy to identify the morphology, chemical composition, and crystalline phases of the deposited films, and diffuse reflectance spectroscopy was used to calculate the band gap width. The films showed characteristics of absorbing material in the visible region with band gap values from 1.43 eV to 1.5 eV. However, the sample treated for 3 h had a compact coating with a thickness of 1.46 µm and band gap energy of 1.43 eV, showing the applicability of the CCPD technique for synthesizing copper oxide absorber layers with an optimum band gap in a single deposition step.