Structural, electronic, and optical properties of chromium oxynitride thin films grown by RF magnetron sputtering

Chromium nitride (CrN) exhibits interesting structural, electronic, and optical properties, making it a promising candidate for a wide range of advanced technological applications. This study presents a comprehensive investigation into the structural, electronic, and optical characteristics of both CrN and chromium oxynitride thin films. The films were grown on Si (001) and fused silica substrates using a radiofrequency magnetron sputtering system. These thin films were produced under varying conditions by adjusting the flow rates of nitrogen and oxygen reactive gases to alter their stoichiometry. The effects of these growth parameters have been examined on their structural properties, charge transport behavior, and bandgap. As nitrogen and oxygen flow rates increased, the films demonstrated an increasing trend in resistivity and bandgap. Interestingly, the Hall coefficient showed a shift from negative to positive values based on the growth conditions, indicating a change in the majority carrier from electrons to holes. Notably, the bandgap varied from 1.36 eV to 3.56 eV showing the bandgap tunability due to film growth conditions, which has important implications for photovoltaic applications.