Local structure of Mn dopants in CuAlS2 and CuGaS2

The local structure around Mn atoms in Mn-doped CuAlS2 and CuGaS2 chalcopyrites is investigated using the X-ray absorption fine structure method. Extended X-ray absorption fine structure spectroscopy (EXAFS) and X-ray absorption near-edge spectroscopy measurements at the Mn K-edge indicate that Mn substituents on the cationic atoms sites. In the CuAlS2 structure Mn is located at both Cu and Al sites, with a preference for the Cu sites for higher Mn concentrations. Discrimination between Mn at two cationic sites is impossible for CuGaS2:Mn using EXAFS due to almost identical photoelectron scattering amplitudes and phases for Cu and Ga atoms. The nearest-neighbour Mn-S distance for all studied compositions is close to 2.41 angstrom which us a typical value for the Mn-S tetrahedral bond length. (c) 2008 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim