Production of large scale polycrystalline MoS₂ films

Growth of large area (≈︂10 cm2) type II MoS2 films by physical vapour transport is reported for the first time. The crystal growing technique used for these films, which have exceptional properties for lubrication and photovoltaic applications, is described in full. It is found that both edge island and island formation, characteristic of type I crystal morphology, takes place when the higher temperature end of the temperature gradient used in the preparation remains below 1070 °C. When the higher temperature approaches this value, a thick film comprising exclusively of type II platelets forms on the walls of the sample vessel immediately underneath the usual type I crystallites. A model in which crystal imperfections act as nucleation centres is used to explain why crystal growth follows the observed behaviour under different temperature regimes.