Study Of The Structural, Optical And Electrical Properties Of Filmscr₂O₃:Au Deposited By Thermochemical Spray Technique

Abstract

Thin films of gold-doped chromium oxide were prepared.Cr₂O₃:Au nanoparticles with doping ratios (2–8%) were prepared
using the thermochemical spray technique, and their structural, optical, and electrical properties were studied. X-ray
diffraction (XRD) revealed that the primary phase is rhombohedral Cr₂O₃, with Au (FCC) peaks appearing at higher doping
ratios. FWHM calculation (Scherrer equation) showed a decrease in crystallite size from approximately 29 nm to 24 nm
with increasing doping. Scanning electron microscopy (SEM/EDX) images confirmed a decrease in the grain size from ~85
nm at 2% to ~53 nm at 8%, with a rougher surface rich in active sites. Optically, the absorbance increased and the
transmittance decreased with increasing Au content, and the direct energy gap decreased from ~3.05 eV to ~2.72 eV,
attributed to localized surface plasmon effects, the formation of localized energy levels, and Urbach tails. Electrically, Hall
measurements showed that all films were p-type, with carrier concentration and mobility increasing with increasing doping,
reflected in improved conductivity and reduced resistivity. These results demonstrate that doping Cr₂O₃ with gold via CSP
improves the microstructure, optical response, and electrical transport of the films, making them a promising candidate for
advanced electronic and optoelectronic applications.