Morphology and low-temperature photoluminescence investigation of bat-like Li-doped ZnO nanostructures

The bat-like ZnO: Li multi-branched nanostructures grown on Si substrates have been successfully fabricated by simple thermal evaporation method. The morphology of the as-prepared sample was characterized by scanning electron microscopy. The results show that each individual product looks like a bat of baseball composed of a top of hexagonal prism, a continuous round table, and a homogeneous bat. The room temperature Raman spectrum indicate that the Li ions have been doped into the lattice position of Zn ions and increase the free carrier concentration. The low-temperature photoluminescence spectra show that the existence of a shallow acceptor at 138 meV above the VBM in the Li-doped samples from the DAP luminescence at 3.235 eV. A Li-related defect complex is made responsible for this shallow acceptor state. With the increase of temperature, the phenomenon of red-shift for the emission peaks is shown.