PHOTOLUMINESCENCE AND ELECTRICAL-PROPERTIES OF SN-DOPED CUGASE2 SINGLE-CRYSTALS

Hall-effect and photoluminescence measurements have been carried out o n Sn-doped CuGaSe2 single crystals. The doping was performed either du ring chemical vapor transport growth with iodine or by a diffusion ste p at temperatures between 200 and 400 degrees C. Room temperature resi stivity can be varied in the range between 10(-2) and 10(6) Omega cm. Hall-effect data can be explained using a model containing two accepto r levels, one of which is very shallow, and a donor level. Due to dopi ng the concentration of the first acceptor, whose activation energy is 59 meV, is decreased and the donor concentrations increased, but no n -type conductivity was observed. The photoluminescence spectra can be explained by an acceptor level of 50 meV, two donor levels of 80 and 1 10 meV, respectively, and a deep state of 400 meV. V-Cu, V-Se, V-Se co mplexes, and Sn on cation lattice sites are suggested as origins of th ese states. (C) 1996 American Institute of Physics.