Annealing Effects of CuInS2 Single Crystals Grown by Traveling Heater Method

Photoluminescence (PL) and piezoelectric photoacoustic (PPA) measurements are carried out at liquid nitrogen temperature for as-grown and vacuum annealed CuInS2 single crystals grown by a traveling heater method (THM). A new peak, due to S vacancy (VS) defect, is observed in the PPA spectrum after the vacuum annealing. A donor-acceptor pair (DAP) emission band which is due to a recombination between the V donor and In vacancy (VIn) acceptor appears while a DAP (VS donor and Cu vacancy (VCu) acceptor) emission band disappears in the PL spectrum after the vacuum annealing.