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TT: Fachverband Tiefe Temperaturen

TT 7: Matter at Low Temperature: Poster Session

TT 7.1: Poster

Montag, 25. Februar 2008, 14:00–18:00, Poster B

Combined experimental and computational study of structure and electronic properties of the chalcogenide-free phase-change material Ge_xSb_100−x — •Peter Zalden, Dominic Lencer, Michael Klein, Martin Salinga, and Matthias Wuttig — I. Physikalisches Institut (IA), RWTH Aachen, 52056 Aachen

Phase Change Random Access Memory (PCRAM) has turned out to be the most promising candidate for future non-volatile memory cells. A PCRAM cell features a reversibly switchable phase change material, whose electrical resistance differs significantly between the crystalline and a melt-quenched amorphous phase. Suitable materials need to be capable of ultrafast switching between the two phases. Ge₁₅Sb₈₅ has been reported to be such a material, that - unlike conventional phase change materials, like Ge₂Sb₂Te₅ - is free of chalcogenides.

In this study, structural modifications in sputtered thin films during the phase change from the as-deposited amorphous to the crystalline phase are analysed, employing a combination of Differential Scanning Calorimetry (DSC) and X-Ray Diffraction (XRD). This survey includes a determination of transition temperatures, an investigation of crystallization kinetics and structural properties of polycrystalline films. Complementary, the structure of crystalline compositions of Ge_xSb_100−x is object of an ab initio study. Density Functional Theory (DFT) is employed allowing to study the variation of structural and electronic properties upon the addition of germanium. A comparison to conventional tellurium based phase change materials is presented and in conclusion the suitability for PCRAMs is evaluated.