Growth, structure and optical properties of amorphous or nano-crystalline ZnO thin films prepared by prefiring-final annealing

摘要

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 X-ray 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°C-200°C for 60 minutes, while highly c-axis oriented ZnO films were obtained by prefiring at high temperature, 400 °C and 500 °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 °C. The PL spectra of amorphous ZnO thin films annealed at 100 °C -200 °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 °C, the PL spectra of the films were greatly deteriorated, the UV peak was diminished.