Influence of S/Mn molar ratio on the morphology and optical property of γ-MnS thin films prepared by microwave hydrothermal

Well crystallized gamma-MnS thin films were successfully synthesized at low temperature and short processing time via a novel microwave hydrothermal (M-H) process without any complexing agent by using manganese chloride and thioacetamide as source materials. The influence of different S/Mn molar ratio in the precursor solution on the phase compositions, morphologies and optical properties of the as-deposited films was investigated. The as-deposited gamma-MnS thin films were characterized by means of X-ray diffraction (XRD), X-ray photoelectron spectroscopy (XPS), field emission scanning electron microscopy (FESEM) and ultraviolet-visible (UV-vis). Results show that the wurtzite phase gamma-MnS thin films with good crystallization can be achieved when S/Mn molar ratio is controlled at 2.0-4.0. The deposited gamma-MnS thin films exhibit (100) orientation growth with the thickness of 300-500 nm. With the increase of S/Mn molar ratio from 2.0 to 4.0, the orientation growth is weakened while the dense and uniform of the as-deposited gamma-MnS thin films are obviously improved and the corresponding band gap of the thin films increase from 3.88 to 3.97 eV. (C) 2012 Elsevier B.V. All rights reserved.