EXTRINSIC PHOTORESPONSE AND PHOTOLUMINESCENCE OF CUINSE2 CRYSTALS GROWN WITH A DEVIATION FROM VALENCE STOICHIOMETRY

Extrinsic photoresponse spectra (T = 300 K) and photoluminescence spec tra (T = 77 K) of CuInSe2 single crystals grown with the deviation fro m valence stoichiometry are studied for point defect identification. T he main peaks of pbotoresponse and photoluminescence correlate each ot her. The characteristic spectral singularities at 1.00, 0.98-0.97, 0.9 4, 0.92-0.89, and 0.72 eV have been attributed to photoactive and radi ative transitions through the donor (V-Se,In-Cu) and acceptor (V-Cu,Cu -In,Se-i) levels. The shift of the extrinsic photoresponse peak to lon g wavelengths (0.92-->0.89 eV) by the V-Se point defect has been found at increasing deviation from valence stoichiometry Delta Z<0. The imp urity subband formation has been suggested as very probable in the cry stals with elevated Delta Z. (C) 1997 American Institute of Physics.