Structural and Photoluminescence Study of Coevaporated CuInSe2/Si(100) Thin Films

Microstructural and radiative properties of CuInSe2 films prepared by three-source evaporation have been investigated by transmission electron microscopy (TEM), X-ray diffraction (XRD), energy dispersive spectroscopy (EDS) and photoluminescence analysis (PL). To identify the energy levels associated with various defects, photoluminescence measurements have been carried out on as-deposited and annealed polycrystalline CuInSe2 thin films deposited onto (100)-oriented Si wafers doped with 1015/cm3 of boron. The behavior of PL spectra as function of temperature and excitation intensity is reported. PL spectra of thin films before and after annealing in argon atmosphere at 400 °C show emission peaks ranging from 0.88 to 1 eV. Annealing strongly increases PL signal at 0.958 eV. A mechanism that provides a qualitative explanation for the observed PL results is described.