Cathodoluminescence Evaluation of Defect Structure in Hydrothermally Grown ZnO:Sb Nanorods

Cathodoluminescence emission of hydrothermally grown antimony doped ZnO nanostructures with different antimony doping (2.5, 4.8, and 11.8 at%) was studied in a scanning electron microscope (CL-SEM). Incorporation of antimony results in formation of mostly nanorods with low aspect ratio together with some Sb-rich nanoparticles. Transmissibn electron microscopy (TEM) of the Sb-doped samples revealed delaminated {10-10} planes produced by antimony surface segregation. CL spectra of the as-grown samples revealed well defined emission bands centered at 3.2, 2.74 and 2.0 eV, attributed to excitonic recombination, and the so-called blue and yellow emissions, respectively. It was observed that the intensity of the blue emission depends strongly on antimony content, suggesting the formation of point defects on Sb doping. While the yellow emission red-shifted after thermal annealing, either in argon or oxygen atmosphere, the intensity of the blue band decreases considerably; such behavior is explained through the reduction of the population of Zn(i) defects.