Determination of the Crystallisation Kinetics of Fast-Growth Phase-Change Materials for Mark-Formation Prediction

A mark simulation tool for fast-growth phase-change materials was developed to predict the formation and erasure of amorphous marks in phase-change discs that are based on doped Sb 2 Te compositions. One of the main challenges of such a simulation tool is the accurate determination of the input parameters. The thermal conductivity of the thin films in the recording stack was determined from melt-threshold experiments in combination with numerical modelling. The crystallisation process, modelled as crystal growth from a crystalline-amorphous interface, is governed by the temperature-dependent velocity of crystal growth. In this paper, we discuss a procedure for measuring the low-temperature velocity of crystal growth from the size of an amorphous mark and the time required for complete erasure under isothermal conditions. Furthermore, to determine the velocity of crystal growth in the temperature range encountered during recording conditions, we performed time-resolved erasure experiments in combination with numerical modelling. The derived time-dependent growth velocity was used in a numerical model to simulate the formation of amorphous marks. Transmission electron microscopy (TEM) measurements of recorded marks were compared to predicted mark shapes to validate the numerical model.