Effect of Li incorporation on the structural and optical properties of ZnO

This paper presents the structural and optical properties of the as-prepared and lithium-doped ZnO at different percentages of Li incorporation (5%–15%) in ZnO. Effect of doping with various percentages of Li at a particular annealing temperature of 600 C is studied. The samples are characterized by X-ray diffraction, absorption spectroscopy, photoluminescence and Raman spectroscopy. The X-ray diffraction and micro-Raman spectroscopy confirm that the lithium substituted zinc and retains the wurtzitic structure of the lattice. Such substitutional Li in ZnO gives rise to shallow acceptor levels and contributes to the p-type conductivity. From the results of the absorption spectroscopy we observed the evidence of shallow levels upon doping and we also determined the bandgap of the materials which is found to be 3.36 eV. Photoluminescence studies reveal that no deep level is formed. The electrical measurements show that the Li-doped samples are p-type in nature and this is due to substitutional Li.