Crystallization kinetics in (AgSbTe)x(In1−ySby)1−x films used in optical data storage

Abstract

In phase change recording, higher linear densities can be achieved with materials in which crystallization is dominated by growth. AgInSbTe alloy based thin films appear to be the latest promising materials for optical data storage that has drawn worldwide attention. In these films, marks can be written with sharper edges and lower jitter. Films of (AgSbTe)x (In1−ySby)1−x material with different compositions (x = 0.2, 0.3, 0.4 keeping y = 0.7) were deposited using thermal evaporation technique under a high vacuum of 10−6 torr. The results of Differential Scanning Calorimetry (DSC) under non-isothermal conditions with different heating rates (5, 10, 15, 20° K/min) are reported and discussed here. The glass transition temperature Tg and the onset crystallization temperature Tc were found to be dependent on the composition as well as on the heating rate. The activation energy for glass transition Eg and the activation energy for crystallization Ec are calculated using Kissinger’s equation and their compositional dependence is discussed. The glass forming ability lies in the range 0.4–0.6.The present investigations indicate that the above-mentioned quaternary material with a typical composition (x = 0.2) is good for phase change optical memory.