Tuning of structural and optical properties of reactively sputtered MoOx films

MoOx films were deposited using reactive sputtering of Mo under varying oxygen flow in the plasma ambient. The films showed a broad X-ray diffraction peak corresponding to MoOx structure. The surface morphology has been influenced significantly with the oxygen content in the plasma during the process of film deposition. The as-deposited films were porous at lower oxygen flow rate (< 10 sccm), while it showed coarse structure at the higher flow rates (> 15 sccm). The compositional analysis revealed that the films are sub-stoichiometric and the weight ratio of O/Mo varied from 1.5 to 2 in the O2 flow range of 5–25 sccm. The sub-stoichiometric phases of MoO3 were detected from FTIR analysis. The optical characteristics showed that the films were highly transparent (> 85 ϕ_b 0.86 eV and a minimum leakage current, Io 5.81 × 10–11 A at the higher O2 flow rates (> 15 sccm), which changed significantly with the oxygen flow rate. The study demonstrates the tunability of structural and optical characteristics, which have been significantly influenced by tuning the plasma ambient during the film deposition.