Sharp optical emissions from Cu-rich, polycrystalline CuInSe2 thin films

Optical properties of Cu-rich CuInSe2 thin films prepared by the selenization of Cu/In/Cu alloys in a H2Se atmosphere have been studied by photoluminescence (PL) spectroscopy. PL spectra of as-grown samples were dominated by transitions due to intrinsic defect levels, which are ascribed to V-In (24 meV), Cu-In (75 meV), and Cu-i (53 meV). After chemical etching (10% KCN), emission lines attributed to free and bound excitonic emissions and their LO phonon replica became visible, Accurate analysis of the peak positions revealed values of 4.3 meV, 1.0441 eV, ana 28.7 meV for the binding energy of the free exciton, the band gap, and the value for the LO phonon, respectively. (C) 1997 American Institute of Physics.