Mixed Phase Compositions of MoS2 Ultra Thin Film Grown by Pulsed Laser Deposition

Abstract We demonstrate the growth of ultra thin film of molybdenum disulfide on semi-insulating GaN/ c -Al 2 O 3 (0001) substrates by pulsed laser deposition. The sample was characterized by Atomic force microscopy, Raman spectroscopy and X-ray photoelectron spectroscopy. The MoS 2 atomic force microscopy images show a root-mean square roughness of about 0.11 nm with some regions of clustered growth and/ or disordered surfaces. The characteristic separation between two Raman active modes has been found to be 21.6 cm -1 , suggesting that the grown MoS 2 film is bi-layer. Using X-ray photoelectron spectroscopic measurements, we observe the presence of mixed phase MoS 2 thin film with stoichiometric mole ratio of S/Mo is about 1.85, suggesting that the film is slightly sulfur deficient under our experimental conditions.