Regensburg 2007 – scientific programme
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O: Fachverband Oberflächenphysik
O 34: Methods: Atomic and Electronic Structure I
O 34.7: Talk
Tuesday, March 27, 2007, 17:15–17:30, H42
1T−TiSe2: Semimetal or Semiconductor? — •Julia Rasch, Torsten Stemmler, and Recardo Manzke — Institut für Physik, Humboldt-Universität zu Berlin, Newtonstraße 15, 12489 Berlin
Even though the semimetallic behavior of 1T−TiSe2 seemed to be well established by band structure calculations and previous photoemission results (see e.g. [1]), this conclusion has been challenged recently. Two high-resolution photoemission investigations deduced semiconducting behavior, however with a very small band gap [2,3]. But such a conclusion is afflicted, on principle, by the problem of measuring an unoccupied conduction band by photoemission.
In the present contribution this problem is solved by the idea of H2 O adsorption onto the van der Waals-like surface, causing a distinct bending of the bands and resulting in an completely filled lowest conduction band. The detailed analysis yields undoubtedly semiconducting behavior for 1T−TiSe2 and interesting new properties of semiconductors with extremely small band gaps.
[1] O. Anderson, R. Manzke, M. Skibowski, Phys. Rev. Letters 55, 2188 (1985) [2] K. Rossnagel, L. Kipp, M. Skibowski, Phys. Rev. B 65, 235101 (2002) [3] T.E. Kidd, T. Miller, M.Y. Chou, T.-C. Yang, Phys. Rev. Letters 88, 226401 (2002)