Berlin 2015 – scientific programme

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O: Fachverband Oberflächenphysik

O 38: Semiconductor Substrates

O 38.6: Poster

Tuesday, March 17, 2015, 18:15–21:00, Poster A

Point defects and diffusion on Bi2Te3 surfaces — •Mert Taskin¹, Ilker Oztoprak¹, Dilek Yildiz¹, Carl Willem Rischau², Cornelis J. van der Beek², Alberto Ubaldini³, and Oguzhan Gurlu¹ — ¹Istanbul Technical University, Istanbul, Turkey — ²Ecole Polytechnique, Palaiseau, France — ³Université de Genéve, Geneva, Switzerland

Bi2Te3 was shown to be a topological insulator besides being a thermoelectric material, yet the knowledge on the atomic scale defects and their effect on the local electronic structure is still incomplete. Bi2Te3 has rhombohedral crystal structure and bonds between the atoms of Bi/Te1 are the strongest in the lattice. In contrast, Te1/Te1 interface has just van der Waals bonds in between them. Consequently the crystals can be cleaved on this plane and the Te1 surface can be imaged with scanning tunneling microscopy (STM) with out need for further surface preparation. Despite its inertness, point defects were observed on the Te1 surface. In addition to these defects we have observed vacancy defects and clusters on the Te1 surface. In order to understand the nature of these defects, we performed time lapse STM imaging by means of which we have observed their diffusion. Moreover, bias dependent images have shown that the defects were not of single type.