Understanding the phase-change mechanism of rewritable optical media

The phase-change mechanism of the rewritable optical media was studied. An amorphous as-deposited GST layer was crystallized by exposure to a laser beam of intensity sufficient to heat the material to a temperature slightly above the glass-transition temperature. It was observed that crystalline GeTe possessed a certain amount of vacancies on Ge sites. It was found that GST can be viewed as being built from well-defined rigid blocks of the composition Ge ₂Sb₂Te₅. It was suggested that the mechanism of the structural phase transition provides potentially critical insight in the search for better performing materials.