Optical properties of high-quality CuInSe2 single crystals

CuInSe2 single crystals have been studied employing photoluminescence (PL), optical reflection (OR), optical absorption (OA) and wavelength derivative reflection (WDR) techniques at temperatures from 4.2 to 300 K. Exciton-rel ated peaks were observed in the near-band-edge region of the PL spectra: se veral narrow lines, with full width at half maximum (FWHM) of about 0.3 meV , and two wider peaks (FWHM about 0.7 meV) at 1.0414 (A) and 1.0449 eV (B). The A and B peaks were also observed in the OR and OA spectra and identifi ed as A and B free excitonic states. The narrow lines were attributed to bo und exciton recombination on intrinsic defects. A third exciton resonance ( C) was observed in the WDR spectra at 1.2779 eV. The crystal-field and spin -orbit splittings were derived to be 5.3 and 234.7 meV, respectively. (C) 2 000 American Institute of Physics. [S0003-6951(00)00337-5].