Structural and Optical Properties of Magnetron-Sputtered Chromium Oxynitride Thin Films

Doping non-metal elements into Cr₂O₃ can tailor its properties, making it more efficient for applications like sensors or photocatalysis. For this purpose, the current research work presents the impact of nitrogen doping on the structural and optical properties of Cr₂O₃ thin films. Pure and N-doped Cr₂O₃ (Cr₂O_3−xN_x) thin films were synthesized using the DC reactive magnetron sputtering approach. The stoichiometry was obtained by raising values of x, where x = 0, 0.125, 0.25, and 0.50. X-ray diffraction analysis confirmed the rhombohedral crystal structure without the presence of any other secondary phase in undoped and N-doped Cr₂O₃ thin films. Furthermore, crystallinity and average crystallite size have enhanced by doping. Field emission scanning electron micrographs disclosed that the surface morphology of the prepared samples changed considerably with doping. A thorough optical investigation was carried out by spectroscopic ellipsometry. Several optical properties significantly changed with dopant content. The reduction in the optical bandgap from 2.50 eV to 1.82 eV, with N-doping was observed. The study demonstrated that N-doping improves the structural and optical properties that make it a promising candidate for optoelectronic applications.