Photoluminescence and the tetragonal distortion in CuInS2

Low temperature photoluminescence (PL) measurement of a deep-donor-deep-acc eptor (DD-DA) pair recombination emission of close DA pairs in CuInS2 at v = 0.62 eV reveals two well resolved lattice vibrational modes, of energy (h ) over bar omega (1) = 40.5 meV and (h) over bar omega (2), = 8 meV. Furthe rmore, the recombination emission has an additional fine structure of Delta E= 2 meV. It appears that the 2 meV fine structure can be interpreted as b eing due to a small difference in the DA separation between two otherwise e quivalent interstitial donor sites. This is due to the tetragonal lattice d istortion in the CuInS2 structure. The measured full width at half maximum, inclusive of instrumental resolution, of these two zero-phonon-emission li nes was approximately 0.6 meV at T=8 K. (C) 2001 Elsevier Science B.V. All rights reserved.