Recombination processes in Te-doped ZnO microstructures

Abstract

Cathodoluminescence (CL) of Te doped elongated ZnO microstructures obtained by a vapour-solid (V-S) technique has been investigated. The CL intensity changes along the microstructures axis are related to the gradient of Te content, which influences the intensity of the ZnO deep-level (DL) emission band. The main defects are vacancy complexes which are partially passivated by the isoelectronic Te doping. The weight on the total luminescence of the radiative processes related to defects has been estimated. A straightforward method based on the measurement of the band-to-band luminescence intensity under constant excitation and experimental conditions has been used. The recombination lifetimes for transition through defect levels were also estimated. [GRAPHICS] SEM image and cathodoluminescence emission of needle- and pencil-like TeO2-doped ZnO microstructures.