Time-resolved photoluminescence studies of bound excitons in CuInS2 crystals

The time-resolved photoluminescence of bound excitons in bulky single crystalline CuInS2 grown by the traveling heater method is investigated. It is found that radiative decay of the bound exciton at 1.530 eV is exponential with two characteristic decay times while that of the bound excitons at 1.525 and 1.520 eV is well-represented by a single exponent at low temperatures. The radiative lifetimes of the bound excitons,at 1.530, 1,525, and 1.520 eV are obtained to be 500 ps, 2.1 ns, and 3.5 ns, respectively. According to our estimates, a neutral charge is to be assigned to the defect centers associated with the observed bound excitons. (C) 2004 American Institute of Physics.