Compound materials for reversible, phase-change optical data storage

Results of rapid (laser induced) and slow (heating stage induced) crystallization studies on Te1-xGex, 0≤x≤0.6, are reported. The time it takes to laser crystallize varies with x by more than four orders of magnitude. Films with stoichiometric compositions, Te and GeTe, can be crystallized using laser pulses of less than 100 ns duration. Unlike Te, which spontaneously crystallizes at room temperature, GeTe has a crystallization temperature of >150°C. From these results we argue that, in general, compound materials allow realization of fast-switching, reversible, phase-change optical recording media. Furthermore, this fast-switching capability, from the amorphous to the crystalline state and back, can be attained simultaneously with long term data (amorphous phase) stability, provided the melting temperature of the compound is sufficiently high.