GeSbTe

GeSbTe, Germanium-Antimony-Tellurium or GST is a phase change material from the group of chalcogenide glasses, used in rewritable optical discs and phase-change memory applications. Its recrystallization time is 20 nanoseconds, allowing bitrates of up to 35 Mbit/s to be written, and direct overwrite capability up to 106 cycles. It is suitable for land-groove recording formats. It is often used in rewritable DVDs. New phase-change memories are possible using n-doped GeSbTe semiconductor. The melting point of the alloy is about 600 °C (900 K) and the crystallization temperature is between 100-150 °C.

During writing, the material is erased, initialized into its crystalline state, with low-intensity laser irradiation. The material heats up to its crystallization temperature, but not its melting point, and crystallizes. The information is written at the crystalline phase, by heating spots of it with short (<10 ns), high-intensity laser pulses; the material melts locally and is quickly cooled, remaining in the amorphous phase. As the amorphous phase has lower reflectivity than the crystalline phase, data can be recorded as dark spots on the crystalline background. Recently, novel liquid organogermanium precursors, such as isobutylgermane (abbr: IBGe) and tetrakis(dimethylamino)germane (abbr: TDMAGe) were developed and used in conjunction with the metalorganics of antimony and tellurium, such as tris-dimethylamino antimony (TDMASb) and Di-isopropyl telluride (abbr: DIPTe) respectively, to grow GeSbTe and other chalcogenide films of very high purity by metalorganic chemical vapor deposition (MOCVD). Dimethylamino germanium trichloride (abbr: DMAGeC) is also reported as the chloride containing and a superior dimethylaminogermanium precursor for Ge deposition by MOCVD.