Regensburg 2007 – wissenschaftliches Programm
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O: Fachverband Oberflächenphysik
O 70: Methods: Atomic and Electronic Structure III
O 70.6: Vortrag
Freitag, 30. März 2007, 11:30–11:45, H42
Band structure mapping and calculations of CuInS2 (001) — •Carsten Lehmann1, Christian Pettenkofer1, and Volker Eyert2 — 1Hahn-Meitner-Institut, SE6, Glienicker Strasse 100, 14109 Berlin, Germany — 2Universität Augsburg, Inst. f. Physik, Universitätsstrasse 1, 86135 Augsburg, Germany
The ternary compound semiconductor CuInS2 is used as an absorber material for thin film solar cells. A better understanding of the detailed electronic structure might lead to an improvement of the junction properties with respect to the still limited photo voltage of the present devices. We report on band structure mapping via ARUPS on thin epitaxial layers of CuInS2 (001) prepared on sulfur passivated GaAs (100). To have a better control on the deposition process we introduced a MOMBE type deposition with an organic sulfur precursor. Samples were prepared and precharacterized in a dedicated UHV deposition and analysis system. ARUPS measurements were conducted at the beamline TGM7 at BESSY II. We will discuss the experimentally determined band structure in comparison to recent augmented spherical wave (ASW) calculations as based on density functional theory and the local density approximation (LDA). Beside earlier calculations presented by Zunger for some high symmetry directions along kperpendicular our calculations include for kparallel the experimental parameters of an ARUPS experiment thus allowing a direct comparison with our experimentally derived data rather than an idealistic run on the boundary of the brillouin-zone. Additionally we derive the effective mass from the valence band curvature.