Berlin 2015 – wissenschaftliches Programm

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O: Fachverband Oberflächenphysik

O 99: Semiconductor Substrates: Structure, Epitaxy and Growth

O 99.7: Vortrag

Freitag, 20. März 2015, 12:00–12:15, MA 042

Investigation of the surface termination of BiTeI by combined STM/AFM — •Julian Berwanger, Florian Pielmeier, and Franz J. Giessibl — Institut für Experimentelle und Angewandte Physik der Universität Regensburg, 93053 Regensburg, Deutschland

Cleaved BiTeI surfaces consist of domains which are either terminated by Te or I [1-3]. The size of these domains depends on the bulk crystallinity of the sample and ranges from 100 µm [1] to 100 nm [3]. The samples investigated here by a combination of scanning tunneling microscopy (STM) and atomic force microscopy (AFM) also consist of domains with smaller size. We find a similar surface structure as reported in Ref. 3 at 4.5K with plain STM in our room and low temperature STM/AFM experiments. Two different step heights are observed by STM in Ref. 3 and our experiments: 0.7 nm and 0.2 nm. The larger step height corresponds to the height of a -Bi-Te-I- stack. The smaller step height was also suggested to be a structural step caused by a stacking fault [3]. In contrast, the atomically resolved STM/AFM data of the smaller "step" suggests that this is indeed an atomically flat layer. The observed step height in STM is a purely electronic effect due to the different density of states at the Fermi-level of Te- and I-terminated surfaces. [1] Crepaldi et al. Phys. Rev. Letters 109, 096803 (2012) [2] Landolt et al. Phys. Rev. Letters 109, 116403 (2012) [3] Butler et al. Nat. Com. 5, 4066 (2014)