Microstructural analysis of quaternary alloy (AgInSbTe)-based films for optical data storage

Abstract

In phase change recording, higher linear densities can be achieved with materials in which crystallization is dominated by growth. This is due to the fact that marks can be written with sharper edges, which give rise to lower jitter. Therefore AgInSbTe alloy based thin films appear to be one of the latest promising materials for optical data storage that has drawn worldwide attention. In the present paper (AgSbTe) x (In1-ySby) 1-x quaternary alloy based films for x = 0.2, 0.3, 0.4 and y = 0.7, were deposited using thermal evaporation technique under a high vacuum of 10-6 torr. The potentiality of the above mentioned films for a phase change optical memory was confirmed using Differential Thermal Analysis (DTA). The results show that this material has good glass forming ability. Further the micro-structural details of the films were studied using SEM (Scanning Electron Microscopic) technique. We also investigated the effect of 1hour thermal annealing on grain size of the films. Thermal annealing of the prepared films was done at different temperatures ranging between 200°c-400°c through radiant heating in vacuum at a pressure of ~10-5 torr. The micro-structural analyses of the as-deposited and annealed films are presented here. This also explains the effect of change in composition as well as change in annealing temperature on the crystalline phases formed on the film.