Multiple phase transitions in GeTe films. Dynamics and film structure

Electron pulse-crystallization of amorphous Ge0,8Te0,2 films, serving as a model substance for multiple transitions, is investigated by “time-resolved” TEM. Precipitation and amorphization of Te crystallites, and generation of different textures of crystalline GeTe successively occur during a μs annealing pulse, depositing 1.1 kW/cm2 in the film. The growth velocities of the different GeTe textures range from 0.3 to 10 m/s at the beam centre, dropping by more than one order of magnitude beyond the irradiated area. The various phases spatially separate in concentric regions, fast transitions being characterized by a sharp demarcation between the participating phases.