Journal of Applied Crystallography

Volume 40, Part 5 (October 2007)

research papers

J. Appl. Cryst. (2007). 40, 841-848 [ doi:10.1107/S0021889807032220 ]

Grain-size distributions and grain boundaries of chalcopyrite-type thin films

D. Abou-Ras, S. Schorr and H. W. Schock

Abstract: CuInSe₂, CuGaSe₂, Cu(In,Ga)Se₂ and CuInS₂ thin-film solar absorbers in completed solar cells were studied in cross section by means of electron-backscatter diffraction. From the data acquired, grain-size distributions were extracted, and also the most frequent grain boundaries were determined. The grain-size distributions of all chalcopyrite-type thin films studied can be described well by lognormal distribution functions. The most frequent grain-boundary types in these thin films are 60°-<221>_tet and 71°-<110>_tet (near) [Sigma] 3 twin boundaries. These results can be related directly to the importance of {112}_tet planes during the topotactical growth of chalcopyrite-type thin films. Based on energetic considerations, it is assumed that the most frequent twin boundaries exhibit a 180°-<221>_tet constellation.

Keywords: electron-backscatter diffraction; chalcopyrites; thin-film solar cells; grain size; grain boundary.