Unraveling the role of plasma focus device power during deposition of copper oxide thin films: Structural and optoelectrical attributes

Abstract

This study introduces a novel approach by utilizing the Plasma Focus Device (PFD) for Cu₂O thin-film deposition, offering a unique method to precisely control film properties. A systematic analysis of the structural, and optoelectrical characteristics across different applied discharge voltages aimed to establish connections between deposition parameters and film attributes. Experimental measurements utilizing instruments like the voltage divider, Rogowski coil current monitor, electron beam detector, and photomultiplier output recorded using a digital oscilloscope to assess plasma focus parameters. Copper oxide thin films were deposited on glass substrates using a plasma focus device, employing varied discharge power and an oxygen-helium gas mixture (50: 50 ratio) for deposition at 20 mTorr. Structural assessments employing X-ray diffraction (XRD) and scanning electron microscopy (SEM) unveiled voltage-induced alterations in crystallite size, orientation, and morphology, impacting the film's crystallinity and surface characteristics. Notably, increasing discharge power led to an enlargement of crystallite size from ≈14 nm to ≈18 nm. The direct energy band gap of the films was found to be decreased from 2.10 eV to 1.81 eV with an increase in the discharge power. In addition, the dielectric parameters were analyzed whereby it was found that the static refractive index n₀ and lattice dielectric constant ε_∞ reduce with increasing the discharge power. Moreover, a Faraday cup (FC) detector within a frequency range of 100 Hz to 5 MHz at room temperature was used to detect the ion beam energy and intensity measurements as well as the estimation of the electron beam energy at the side-on location from the plasma focus device under consideration. This work provides insights into optimizing Cu₂O thin films for optoelectronic applications.