Direct observation of recrystallization and structural transformations in ZnS films under an electron microscope

Abstract

Thin polycrystalline films of ZnS, deposited on a crystalline substrate by thermal evaporation under vacuum, were heated by the electron beam of an electron microscope, causing them to recrystallize. The recrystallization process and the structural transformations that occurred were thus observed directly. Detailed investigations reveal that the structural transformation occurs by a process of repeated microtwinning. Measurement of the average width of the resulting microtwins indicates an average of one stacking fault in every 8 to 10 layers. Polytypes of ZnS appear to be intermediate states in the phase-transformation from the cubic to the hexagonal phase and result from periodic microtwinning.