The rapidly increasing net amount of digital information requires higher data- storage capacities and transfer rates. As a consequence, there is a need for a continuous improvement of the media concept and design. Phase change recording technology offers attractive features for erasable data storage with high density. Further optimization of this technology requires the determination of crystallization kinetics and comprehensive understanding of the underlying mechanisms. In this work we have prepared and investigated the crystallization kinetics of sputter deposited amorphous Ge2Sb2Te5, Ge4Sb1Te5, and Ag5.5 In6.5 Sb59Te29 films. These materials are of great interest in phase change media technology since they enable to write, erase and rewrite information repetitively using optical techniques. They can be characterized by two stable physical phases that exhibit significantly different optical properties. The properties of these materials are compared in regard to data storage applications. Temperature dependent measurements of electrical resistance have been employed to study the kinetics of the structural changes. Corroborative x-ray diffraction measurements reveal that upon annealing the amorphous Ge2Sb2Te5 films crystallize to a cubic structure followed by an hexagonal structure upon further annealing. Both Ge4Sb1Te5 and Ag5.5In6.5Sb59Te29 films crystallize in only one phase namely cubic and hexagonal structure, respectively. The cubic structures for both Ge2Sb2Te5 and Ge4Sb1Te5 alloys are identified with NaCl-type. X-ray reflectometry measurements show that these transformations are characterized by a density increase and a thickness decrease. The build in stresses upon crystallization were determined by employing wafer curvature measurements. Temperature dependence of electrical resistance measurements of films capped with ultra thin layers (Native oxide, ZnS-SiO2, Si3N4, SiO2) show considerable influence on the crystallization kinetics.
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