Observation of Melt Growth Process of Bi and Sn Thin Films

We observed melt-growth process of Bi and Sn thin films by in-situ transmission electron microscopy. After preparing the films with some specified orientations from bulk single crystals of Bi (99.9 and 99.9999 %) and Sn (99.999 %), we partially melted and regrew them by cooling at a nearly constant rate in an electron microscope. In the Bi films, a growing solid-liquid interface was observed to be concave toward melt more frequently than faceted. The movement of the curved interface was sensitive to small fluctuations of the falling temperature, while the faceted interface was insensitive. During the melt growth various crystal defects were introduced, and their density depends on the orientation, purity of films and the cooling condition. In the Sn films, a growing interface was always curved. The defects formed were confined to lineage defects, of which formation was not influenced by the cooling rate but by the film orientation