The Effect of Doping on the Erasure Speed and Stability of Reversible Phase-Change Optical Recording Films

The crystallization kinetics of chalcogenide films, to which small concentrations of foreign elements such as Cu, Co, Pb, Ag and Sb are added, were investigated theoretically. It is found that the critical cooling rate can be taken as the criterion for evaluating the roles of various elements on the erasure speed. Since the elements having lower T g/T m possess higher critical cooling rates, they are favorable for enhancing the erasure speed of the above films. On the other hand, the T g of the elements having lower T g/T m is found to be the main factor in determining the stability of corresponding films at room temperature because these elements possess higher crystallization speed in the temperature range between T g and T m. Therefore, the elements having lower T g/T m and higher T g can be used to improve both the erasure speed and the stability of the reversible phase-change optical recording films.