Doped Ge–Sb–Te phase-change materials for reversible phase-change optical recording

Differently doped Ge–Sb–Te phase-change recording films were prepared by the individual dc magnetron sputtering of Sn5Ge3Sb72Te20, In5Ge3Sb72Te20, Ga5Ge3Sb72Te20 and Bi5Ge3Sb72Te20 targets. A close relationship was observed between surface roughness and reflectivity. The Ge–Sb–Te films doped with Bi showed the highest surface roughness and reflectivity. The phase-change optical disks with Bi-doped Ge–Sb–Te recording films showed the best overwriting characteristics. Therefore, the reversible recording properties of the phase-change optical disk were dominated by the composition of the recording film.