The structural, surface morphological, and optical characteristics of amorphous or nanocrystalline ZnO thin films deposited on soda-lime-silica glass substrates by a prefiring-final annealing process at various temperatures were investigated using Xray diffraction analysis, a field emission-scanning electron microscope, a scanning probe microscope, a ultraviolet-visible-near infrared spectrophotometer, and photoluminescence (PL). The films exhibited an amorphous pattern even when finally annealed at 100 degrees C-200 degrees C for 60 minutes, while highly c-axis oriented ZnO films were obtained by prefiring at high temperature, 400 degrees C and 500 degrees C. A relatively high transmittance in the visible spectra range and clear absorption edges of the films were observed except for the film annealed at 100 degrees C. The PL spectra of amorphous ZnO thin films annealed at 100 degrees C -200 degrees C with strong near-band-edge (NBE) emission were observed while the defect-related broad green emission was nearly fully quenched. After high-temperature prefiring and final annealing at above 300 degrees C, the PL spectra of the films were greatly deteriorated, the UV peak was diminished.

Keywords: ZnO thin films; amorphous pattern; transmittance; NBE emission