Kinetic crystallization behavior of phase-change medium

The crystallization behavior of nominal-composition GeSb2Te4 films prepared by rf-magnetron sputtering are examined. The crystal structures of the as-sputtered and the annealed films at different annealing temperatures are identified by the X-ray diffraction (XRD) method. Two phase transformations occur in the conventional slow heating process when the as-sputtered film is heat-treated from the ambient temperature to its melting point. However, only the amorphous to face-centered cubic (FCC) transformation is allowed when laser annealing with a 10(11)degrees C/min heating rate is applied to heat the films. Consequently we predict that the meta stable FCC phase, instead of the hexagonal closed-packed (HCP) phase, is the dominant crystalline phase in the GeSb2Te4 phase-change recording medium.