Exploring the impact of substrate placement on Cu3N thin films as a solar cell window layer: Structural and optical attributes

Abstract

Copper nitride (Cu3N) thin films have garnered significant interest due to their exceptional stability, corrosion resistance, and optical qualities. In this research, Cu3N thin films were produced through reactive dc magnetron sputtering (dcMS) in a nitrogen/argon atmosphere on glass substrates without any external heat treatment. The study examined the effects of substrate positions from the cathode target, and subsequently film thicknesses, on the structure and optical properties of Cu3N thin films. Different methods were employed to examine the structural and optical characteristics of the films, including X-ray diffraction (XRD), scanning electron microscopy (SEM), and ultraviolet-visible-near infrared (UV–vis–NIR) spectrophotometry in the wavelength range of 400–2500 nm. The XRD patterns indicated a cubic crystal structure for the films with a dominant orientation along the (100) plane, while SEM images displayed uniform and smooth surface morphologies for the films. The UV–vis–NIR spectrophotometry findings demonstrated transmittance above 70% in the visible region for the films, and the optical bandgap values ranged between 2.29 and 2.49 eV. The optical conductivity (σ), electrical susceptibility (χc), and optical electronegativity (ηopt) have been calculated. Furthermore, the nonlinear optical qualities of Cu3N thin films were discussed, including the nonlinear refractive index (n2), the nonlinear optical susceptibility, and the nonlinear absorption coefficient (βc). The Cu3N thin films showed promising optical properties, suggesting their potential use as a window layer in solar cell technology.