Abstract
Photoacoustic (PA) spectra have been investigated using a piezoelectric device and a tunable laser for CuInS2 crystals grown by the traveling heater method. The PA spectrum at 9 K shows two dips located at 1.536 and 1.556 eV corresponding to "A" and "B" free excitons, respectively. The dips of the PA spectrum indicate an increase in the probability of radiative recombination for resonantly excited electron-hole pairs with free exciton energies.