FAST CRYSTALLIZING GESB ALLOYS FOR OPTICAL-DATA STORAGE

A systematic study is presented on the optical and structural transformations induced in amorphous Ge1-xSbx alloys with Sb contents in the 0.71 less-than-or-equal-to x less-than-or-equal-to 0.91 range by irradiation with 250 ns laser pulses. The results show that only those films richer in Sb than the eutectics (x=0.85) show appreciable optical contrast upon irradiation. The dominant role of Sb in the performances of this family of alloys is analyzed. The transition from a low-reflectivity amorphous phase to a high-reflectivity extended solid solution of Ge in crystalline Sb is shown to be the key for a new generation of fast reversible optical storage materials in which amorphous-crystalline cycling using ultrashort laser pulses is feasible.