Excitonic luminescence in CuInSe2

Abstract
Band-edge luminescence of CuInSe2 single crystals was studied in the temperature region between 2 and 300 K. Sharp emission lines were attributed to the decay of free and bound excitons and their phonon replica. Accurate analysis of the peak position revealed values of 4.4 meV and 1.044 eV for the binding energy of the free exciton and the band gap at 2 K, respectively. Investigations on n- and p-type material showed different emission lines, which are ascribed to excitons bound to the different dominating intrinsic defects in these materials. Furthermore, the results are compared to thin-film studies.