Red luminescence in ZnO films prepared by a glycol-based Pechini method

ZnO thin films on fused quartz substrates were prepared by a glycol-based Pechini method. The structural and optical properties were characterized by X-ray diffraction (XRD), scanning electron microscopy (SEM), optical transmittance spectrum, and photoluminescence (PL) spectrum. A red emission around 700 nm was found in PL spectrum, and its peak intensity gained a strong enhancement (∼140%) while annealing temperature increased from 700 °C to 800 °C. The red emission was ascribed to the possible high defect density in boundary layers of nanocrystalline grains.