Effective control over near band-edge emission in ZnO/CuO multilayered films
Abstract
We report on a study of the microstructural and photoluminescent properties of ZnO/CuO multilayered films. Multilayered ZnO/CuO thin films were deposited on amorphous SiO2/Si substrates by a pulsed laser technique and their microstructural and optical properties were characterized by transmission electron microscopy (TEM) and photoluminescence spectroscopy. TEM and XRD analyses of annealed ZnO/CuO films reveal the formation of multiple crystallographic defects and modification of the dominant growth plane, indicating effective doping of Cu atoms into the ZnO lattice. Consequently, near-band-edge emission in ZnO can be controlled through the number of CuO layers. Redshift of the near-band-edge emission peak from 385 nm up to 422 nm is achieved by increasing the number of CuO layers up to a certain number, above which a downward shift is observed. The results demonstrate that the emission properties of ZnO can be modified and precisely controlled by incorporation of CuO thin layers as a Cu-doping source.