Melting of crystalline silicon thin films

•We give a whole picture about the atomic mechanism of melting of crystalline silicon thin films.•We find the formation of a quasi-liquid surface layer.•There is no rigid plane interface between liquid surface layer and solid interior.•Atomic mechanism of melting should not be size dependent for the size range studied. Melting of crystalline silicon thin films is studied by molecular dynamics (MD) simulations using Stillinger–Weber potential. Models are heated up from a crystalline to a normal liquid state. Temperature dependence of total energy and the Lindemann ratio exhibits a first-order-like behavior of the transition at a melting point. Heat capacity of the system exhibits a single peak at around the melting point. Atomic mechanism of melting is analyzed via monitoring spatio-temporal arrangements of the liquidlike atoms occurred during heating process. We find the formation of a quasi-liquid surface layer containing both solidlike and liquidlike atoms, i.e. at temperature around the melting point (Tm), there is a mixed phase of the solidlike and liquidlike atoms in the surface layer. The mechanism of melting of crystalline silicon is different from that of Lennard–Jones crystals and monatomic glass with free surfaces due to the potentials used in simulation and due to sizes of models.