Berlin 2008 – scientific programme

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O: Fachverband Oberflächenphysik

O 36: Surfaces and Films: Forces, Structure and Manipulation

O 36.5: Talk

Tuesday, February 26, 2008, 15:15–15:30, MA 041

Morphology and electronic structure of epitaxially grown CuInS₂ films — •Carsten Lehmann¹, Volker Eyert², and Christian Pettenkofer¹ — ¹Hahn-Meitner-Institut, SE6, Berlin, Germany — ²Universität Augsburg, Inst. f. Physik, Augsburg, Germany

The ternary compound semiconductor CuInS₂ with a direct band gap of 1.53 finds application as absorber material in modern thin film solar cells. For a better understanding of the parameters determining the properties of a junction detailed information on the electronic structure is necessary. We report on ARUPS measurements on thin epitaxial CuInS₂ films prepared on sulfur passivated GaAs(100) and GaAs(111)B. Samples were prepared in a combined UHV GSMBE deposition and analysis system with an organic sulfur precursor. The bandstructure mapping was performed at the beamline TGM7 at BESSY II. The experimentally obtained electronic structure for CuInS₂(001) shows good agreement with augmented spherical wave (ASW) calculations based on density functional theory (DFT) and the local density approximation (LDA). For CuInS₂(112) films deposited on GaAs(111)B substrates we observe a LEED pattern with a sixfold symmetry which is not in accordance with a simple chalcopyrite (112) structure. We will discuss the observed structure within a domain model of the surface and its implications on our obtained spectra.