Regensburg 2016 – wissenschaftliches Programm
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DS: Fachverband Dünne Schichten
DS 12: Postersession DS
DS 12.26: Poster
Montag, 7. März 2016, 17:00–19:00, Poster A
Tunnel diodes—A method to picture quantum correlations in disordered tellurides — Dominik Gholami Bajestani1, •Henrik Padberg1, Tobias Schäfer1, and Matthias Wuttig1,2 — 1I. Physikalisches Institut (IA), RWTH Aachen University, 52056 Aachen, Germany — 2JARA-FIT, RWTH Aachen University, Germany
Phase change materials (PCMs) are promising candidates for a new generation of fast and non-volatile memories unifying flash and DRAM properties. Besides the fast electrical (or optical) switching between amorphous and crystalline phase, storage of additional information in the crystalline state becomes possible because of the resistivity being tunable over several orders of magnitude. The variation of the resistivity stems from different degrees of disorder in the PCM and is linked to quantum correlations. Both effects are known to alter the density of states (DoS). A method to measure the DoS are tunnel diodes, which make use of the tunnel effect and consist of a layer stack with a metal and the PCM separated by a thin oxide layer.
In this study, we investigate changes in disorder and quantum correlation in the PCM Sn1Sb2Te4 (SST) using tunnel diodes. As magnetron-sputtering and subsequent annealing are the best way to control the PCM’s disorder, we have developed an in situ sputter process to guarantee a high quality layer stack. Besides characterization studies of the diodes, the DoS of SST has been examined for different annealing states to link band structure phenomena to the material properties. To probe the DoS (∝ dI/dV), an AC-voltage signal is applied to a biased tunnel diode, at liquid helium temperatures.