Morphological and Electrical Characteristics of Electrodeposited of Cu2O Thin Films due to Variation in the pH of Electrolyte During Growth Process

Cu2O is a semiconductor material featuring a direct bandgap of ~2.0 eV. with high abundant and non-toxic. A thin film of Cu2O was grown using Keithley-2400 source meter unit as the potential source. The electrodeposition was carried out under a constant potential of 200 mV. During the electrodeposition process, both the current dynamics and the pH of the electrolyte were closely monitored and analyzed in relation to the morphological and electrical characteristics of the resulting Cu2O electrode. As the process progressed, a notable shift in the pH of the cupric acetate (Cu(CH3COO)2) electrolyte was observed, dropping from pH 5.6 to pH 5.4 around the 40-minute mark. Scanning electron microscopy (SEM) imaging revealed that optimal material coverage was achieved at approximately 40 minutes of deposition. However, extended deposition times led to the formation of defects within the polycrystalline grains of Cu2O. X-ray diffraction (XRD) analysis indicated the possible deposition of metallic copper on the film after 20 minutes of electrodeposition. Despite the presence of metallic copper, the highest photocurrent transient was recorded for the Cu2O thin film that was electrodeposited for a duration of 40 minutes. The deposition of metallic copper was identified as a drawback, negatively impacting device performance.