Growth and characterization of molybdenum-based oxide thin film by RF magnetron sputtering

Molybdenum oxide thin films exhibit a variety of stable phases. They possess interesting structural, optical, chemical, and electrical characteristics that are appealing for a number of applications in energy storage, sensors, solar cells, infrared detectors, and smart windows. Additionally, molybdenum oxide thin films are mostly preferred in chemiresistive gas sensors, for sensitive detection of nitrogen dioxide (NO2), carbon dioxide (CO2), hydrogen (H2), and ammonia (NH3). In this study, optimized conditions of MoO3 have been investigated for gas sensor applications. Molybdenum oxide thin films have been deposited by Radio Frequency (RF) magnetron sputtering on silicon wafers using a metallic molybdenum target in the presence of oxygen (O2) and argon. In situ heat treatment was applied to form a better crystalline structure of molybdenum oxide thin films followed by an X-Ray Diffractometer (XRD), Scanning Electron v Microscopy (SEM), Photoluminescence, and Electron Paramagnetic Resonance (EPR) were used for the structural, stoichiometric, morphological, and defect concentration analyses respectively. The optical characteristics were analyzed by ellipsometry to gain insight into the semiconducting character of the samples and the sheet resistance was measured by the 4-Point Probe method. Considering the information gathered from the experiments, we discuss the growth conditions in the sputtering system and thickness effect to improve their structural qualities affecting their optical and electrical characteristics.