Regensburg 2010 – wissenschaftliches Programm

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MM: Fachverband Metall- und Materialphysik

MM 26: Poster Session

MM 26.62: Poster

Dienstag, 23. März 2010, 14:45–16:30, Poster C

Structure and negative thermal expansion in Cu(In1-xGax)(S, Se)2 — •Christiane Stephan¹, Susan Schorr², Denis Sheptyakov³, and Hans-Werner Schock¹ — ¹Helmholtz-Zentrum Berlin für Materialien und Energie, Solarenergieforschung, Glienicker Straße 100, 14109 Berlin — ²Freie Universität Berlin, Fachbereich Geowissenschaften, Malteserstraße 74-100, 12249 Berlin — ³Laboratory for Neutron Scattering, ETH Zürich & PSI Villigen, CH-5232 Villigen, Schweiz

Compound semiconductors like Cu(In1-xGax)(S, Se)2 are due to their superior optical and electronical properties successfully used as absorber layers in thin film solar cells. These compounds adopt the chalcopyrite type structure, which is characterized by a tetrahedrally coordination of the cations by anions and vice versa. One of the most intriguing properties of solids whose crystal structures are based on tetrahedrally coordinated ions is their negative thermal expansion. To verify this concept, in-situ neutron diffraction experiments in a temperature range from 290K to 1.5K were performed on Cu(In1-xGax)(S, Se)2 powder samples. The lattice parameters and linear thermal expansion coefficients were determined by Rietveld-Analysis of the neutron diffraction data applying the chalcopyrite structure as structural model and using the FullProf suite software package. Negative thermal expansion coefficients were observed for the Cu(In1-xGax)Se2 compounds, whereas the critical temperature, where alpha(a,c) becomes negative, varies with chemical composition.