Synthesis and characterization of ZnO:Tm3+ based phosphor nanocrystals

G.L. Kabongo, G.H. Mhlongo, B.M. Mothudi, K.T. Hillie, M.S. Dhlamini
University of South Africa, ZA

Keywords: ZnO, photoluminescence, defects, sol gel

Summary:

ZnO quantum dots were successfully prepared by sol gel method. Structural, optical and chemical composition analysis are reported. Average crystallite sizes was determined to be in the range of 5 nm to 7 nm for both un-doped and Tm3+ doped ZnO. The main (101) diffraction peak of the Tm3+ doped ZnO samples was found to be slightly shifted towards lower 2 angles as a result of dopant incorporation due to larger ionic radius of Tm3+ than that of Zn2+. Well-defined exciton absorption bands at 365 nm for un-doped ZnO and 367, 374, 370 nm for, 0.25, 0.5, and 0.75 mol% Tm3+ doped ZnO samples, respectively. The excitonic emission band originating from recombination of free excitonic centers was observed to have increased while the defects emission was observed to have decreased with the increase in the concentration of Tm3+ ions.