Tuning optical and electrical characteristics through Cu doping in spray pyrolysis fabricated Cr2O3 thin films

Abstract

This study focuses on the physical properties of thin films of Cr2O3 and Cu-doped Cr2O3 (1−4 % Cu), with a thickness of approximately ∼500 nm. These films were deposited on preheated soda-lime glass substrates using the spray pyrolysis technique. The characterization of the thin films was carried out through Raman spectroscopy, UV–visible spectroscopy, and the four-point probe technique. The Raman analysis revealed vibrational modes associated with Eg and A1g symmetries in Cr2O3. The optical band gap energy exhibited a decrease from 2.92 eV to 2.6 eV with an increase in Cu content. The study also involved the evaluation of extinction coefficient, refractive index, dielectric constants, and optical conductivity of the thin films. The dispersion of the refractive index was studied using the single oscillator model (Wemple-DiDomenico). The electrical resistivity values decreased from 1000 Ω-cm to 33 Ω-cm with increasing Cu content. Notably, Cr2O3 thin films with 4 % Cu content demonstrated the best figure of merit, recording a value of 4.66 M Ω−1.