Preparation and characterization of polycrystalline MnS thin films by the RF-sputtering technique above room temperature

Polycrystalline MnS thin films have been obtained by the RF-sputtering technique above room temperature for the first time. This could be achieved by adding appropriate amounts of elemental sulfur to the MnS targets, to compensate for the sulfur loss that normally produces off-stoichiometry, amorphous films. The films were prepared at ambient temperature, 120°C and 180°C, while the sulfur concentrations in the target were 0, 5 and 10 at%. The films were characterized by X-ray diffraction, energy dispersive spectroscopy, atomic force microscopy, and UV–Vis spectroscopy. 10 at% was the concentration of additional sulfur at which polycrystalline films could be obtained at substrate temperatures of 120°C and 180°C. However, the addition of sulfur to the targets for growing films at room temperature leads to amorphicity (5 at%) or to a change in the crystal orientation of the films (10 at%). The experimental conditions to obtain single-phase films with the metastable hexagonal ( γ) structure, above room temperature, are reported. From UV–vis spectral data, a bandgap energy value of 3.3 eV was found for γ-MnS films.