Berlin 2018 – scientific programme
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DS: Fachverband Dünne Schichten
DS 17: Poster Session I
DS 17.52: Poster
Tuesday, March 13, 2018, 18:15–20:15, Poster B
Investigation of the Density of States of Phase Change Materials by Tunneling Spectroscopy — •Lisa Metzner1, 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
Due to their unique physical properties, phase change materials (PCM) are promising candidates for future data storage applications. By applying electrical or laser pulses, they can be switched reversibly between an amorphous and a crystalline state on a nanosecond timescale. These states are characterized by a large optical and electrical contrast, which is utilized for rewritable optical data storage and phase change RAM applications. Furthermore, the resistivity can be tuned over several orders of magnitude by disorder control, which allows for possible multilevel memory devices in the future. In order to fully understand the electronic properties of those materials, the density of states (DOS), especially in the vicinity of the Fermi level, is a crucial quantity. This contribution presents the method of tunneling spectroscopy, which allows the determination of the DOS around the Fermi energy with a resolution of up to 0.2 meV, complementing to photoelectron spectroscopy which is typically limited by a resolution of around 0.1 eV. The measurements were performed using tunnel junctions, produced by in-situ sputter deposition in order to prevent the PCM from surface contamination. Besides the introduction of the procedure, tunneling spectra of PCMs with a varying degree of disorder are presented.