Characterization of Ag-Sb-Te Alloy and Their Films for Phase Change Optical Memories

摘要

Ag-Sb-Te alloy and films are developed as Optical recording material based on amorphous - crystalline phase transformation. The crystallization process of Ag-Sb-Te films is systematically studied through measurement of recording characteristics to solve the trade off problem between data stability and erasing sensitivity. Phase change optical recording disks have been found to demonstrate long thermal stability of the amorphous recording marks. In the present work, preparation and characterization of the chalcogenide alloy Ag_x - Sb_(2 (1-x)) - Te_(3(1-x)) with different composition (x = 0.16,0.18 and 0.20) has been presented. Samples were prepared using melt quenching technique and the films were grown by thermal evaporation system. The thermal Characterization of Ag- Sb- Te material was studied using differential thermal analysis (DTA) and Optical Characterization (Transmittanee and reflectance) respectively. The films were studied for both cases: before and after annealing. The Differential thermal analysis curves were recorded for different compositions and Glass transition temperature (T_g), crystallization temperature (T_c) and melting temperature (T_m) have been obtained. It may also be concluded that T_g / T_m ratio is closer to required condition for the phase change optical data storage material. Thermal and optical Characterization shows that the Ag - Sb- Te material is a potential candidate for phase change optical memory application. The optimized composition has also been obtained.