Effect of Annealing Atmosphere on Interface State Density in p-CuO/n-Si Heterojunction Devices: A Capacitance–Voltage Study

Abstract

Thin film p-CuO/n-Si heterojunction devices were fabricated by depositing CuO thin films on n-type silicon substrates using the Spray Pyrolysis Deposition (SPD) technique, followed by post-annealing at 450 °C under air and nitrogen atmospheres. The interface properties of the heterojunctions were investigated using frequency-dependent capacitance-voltage (C–V) measurements carried out over the frequency range of 100 Hz to 1 MHz. The interface state density was estimated from the difference between the quasi-low-frequency and high-frequency capacitances measured at 10 kHz and 100 kHz, respectively. The results indicate that the interface states strongly influence the electrical characteristics of the CuO/Si junction and that the annealing atmosphere plays a significant role in controlling the density of interface states. The study demonstrates that C–V characterization is an effective tool for evaluating the interfacial properties of p-CuO/n-Si heterojunctions and provides valuable insight into the defect states present at the CuO/Si interface.