Substrate temperature effects on the growth and properties of γ-MnS thin films grown by rf sputtering

The growth of manganese(II) sulfide films by radiofrequency sputtering are shown for the first time. Polycrystalline, nearly stoichiometric films of the metastable hexagonal γ-MnS phase were obtained when the substrate temperature was approximately 26°C. For higher substrate temperatures, 120 and 180°C, the films were amorphous and sulfur deficient. The sulfur loss is substrate-temperature dependant. This behavior is discussed in terms of the dissociation of the MnS molecules during the sputtering process and the phase diagram of sulfur. An analysis of the optical transmission spectrum of the γ-MnS films allowed us to estimate their index of refraction in the non-absorbing region of the spectrum and the electronic band gap in the high absorbance region, obtaining an Eg value of 3.47±0.01 eV at room temperature.