Thin films of ${\mathrm{Se}}_{80}$${\mathrm{Te}}_{20}$ were prepared by vacuum evaporation of the polycrystalline bulk alloy at a fast rate onto replicating tape pieces held at room temperature in a vacuum of 5×${10}^{\mathrm{-}5}$ Torr. The alloy films were separated from the tape by dissolving the latter in acetone and were examined in an electron microscope at low electron-beam currents (8 μA). The films were found to be amorphous. On increasing the electron-beam current (to a maximum of 60 μA), the films were found to crystallize very quickly into either polycrystalline or more than one single-crystalline orientation, as observed by the disappearance of the diffuse rings and the appearance of systematic spot patterns and sharp ring patterns. The analysis of the spot patterns revealed that more than one orientation usually occurred in single-crystalline regions. Thus, it is found that ${\mathrm{Se}}_{80}$${\mathrm{Te}}_{20}$ amorphous thin films crystallize in the electron microscope due to electron-beam interaction and lead to more than one single-crystalline orientation of the phase-transformed films. The very fast rate of crystallization, the crystallization of the entire film by irradiation of only one spot, and the observed dendritic growth features confirm that the electron-beam-induced crystallization is ‘‘explosive.’’

• Received 10 August 1987

DOI:https://doi.org/10.1103/PhysRevB.37.720