ABSTRACT
The photoluminescence (PL) spectra of CuInSe2 and CuGaSe2 single crystals have been studied at different temperatures in the range of 4.2 to 300 K. Two components at 1.7210 eV and 1.7281 eV corresponding to the ground (n=1) and the first (n=2) excited states of the direct exciton series have been resolved in the PL spectra at 4.2 K of the CuGaSe2 compound. Using an hydrogen-like approximation the exciton binding energy and direct energy gap are estimated as 9.5 meV and 1.7305 eV respectively. In the PL spectra of CuInSe2 there are free exciton peaks at 1.0408 eV (n =1) and 1.0446 eV (n=2). This material has the energy gap 1.0459 eV and exciton binding energy 5.4 meV at 4.2 K.
