Annealing effects on sulfur vacancies and electronic transport of MoS₂ films grown by pulsed-laser deposition

We have synthesized high quality and large area MoS₂ films on flexible fluorophlogopite substrates using the pulsed-laser deposition (PLD) technique. Annealing in a sufficient sulfur atmosphere was adopted to eliminate oxide molybdenum and sulfur vacancies introduced during the growth in the vacuum chamber. X-ray photoelectron spectroscopy results demonstrate the advantages benefitted from the annealing process. The S/Mo ratio of the annealed MoS₂ film was 1.98:1, which was much closer to the theoretical value. Raman spectroscopy, Photoluminescence spectroscopy, and X-ray diffraction spectroscopy provided direct evidence for the crystallinity improvement. Due to the elimination of molybdenum oxide, the Fermi level was shifted by 0.175 eV, and the conductive type changes from the Ohmic contact to the Schottky contact. The optimized method in this paper makes the PLD-derived MoS₂ films promising candidates for microelectronic device application.