The electrical parameters of n-type and p-type samples were found to be related to the defect chemistry. Optically active point defects were detected, and were identified by using photoresponse and photoluminescence methods at 77 to 300K. Characteristic spectral singularities at 1.00, 0.98 to 0.97, 0.94, 0.92 to 0.89, 0.84 and 0.72eV were attributed to photoactive and radiative transitions due to donor (VSe, InCu) and acceptor (VCu, CuIn, Sei) levels. A shift of the extrinsic photoresponse peak to long wavelengths (from 0.92 to 0.89eV), due to the VSe defect, was found with increasing deviations from valence stoichiometry.

Polycrystalline bulk CuInSe2 with a deviation from valence stoichiometry G.A.Medvedkin, M.A.Magomedov: Solid State Phenomena, 1999, 67-68, 385-90