Stresses, viscous flow and crystallization kinetics in thin films of amorphous chalcogenides used for optical data storage

Modern computers usually contain several kinds of data storage devices. Very frequently magnetic and optical storage media are being used. The latter have become of great interest especially throughout the last decade: nowadays a significant amount of data is being stored on compact discs (CDs) and digital versatile discs (DVDs). Recently rewritable CDs have become commercially available. Their data storage layer usually consists of a thin film of a glass forming chalcogenide alloy (generally a Te alloy), which can be switched by laser heating locally and reversibly from the amorphous to the crystalline state. Rewritable DVDs and random access memories (RAMs) based on Te alloys are currently being developed. Therefore, it is important to enhance the insight into the material properties of Te alloys. For this reason thermal and mechanical properties of sputtered thin films of some of the most frequently used Te alloys Ag0.055In0.065Sb0.59Te0.29, Ge4Sb1Te5 and Ge2Sb2Te5 were studied by differential scanning calorimetry and wafer curvature measurements. The main focus was directed to the study of their amorphous phases