Layered MoS₂ grown on c-sapphire by pulsed laser deposition

Layered growth of molybdenum disulphide (MoS₂) was successfully achieved by pulsed laser deposition (PLD) method on c -plane sapphire substrate. Growth of monolayer to a few monolayer MoS₂, dependent on the pulsed number of excimer laser in PLD is demonstrated, indicating the promising controllability of layer growth. Among the samples with various pulse number deposition, the frequency difference (A_1g-E¹_2g) in Raman analysis of the 70 pulse sample is estimated as 20.11 cm^-1, suggesting a monolayer MoS₂ was obtained. Two-dimensional (2D) layer growth of MoS₂ is confirmed by the streaky reflection high energy electron diffraction (RHEED) patterns during growth and the cross-sectional view of transmission electron microscopy (TEM). The in-plane relationship, (0006) sapphire//(0002)MoS₂ and [2 anti 1 anti 10] sapphire//[0 anti 1 anti 10]MoS₂ is determined. The results imply that PLD is suitable for layered MoS₂ growth. Additionally, the oxide states of Mo 3d core level spectra of PLD grown MoS₂, analysed by X-ray photoelectron spectroscopy (XPS), can be effectively reduced by adopting a post sulfurization process. (copyright 2015 WILEY-VCH Verlag GmbH and Co. KGaA, Weinheim) (orig.)