The impact of morphology upon the radiation hardness of ZnO layers

Abstract

It is shown that ZnO nanorods and nanodots grown by MOCVD exhibit enhancedradiation hardness against high energy heavy ion irradiation as comparedto bulk layers. The decrease of the luminescence intensity induced by 130 MeVXe23+ irradiationat a dose of 1.5 × 1014 cm−2 in ZnO nanorods is nearly identical to that induced by a dose of6 × 1012 cm−2 in bulk layers. The damage introduced by irradiation is shown to change thenature of electronic transitions responsible for luminescence. The change ofexcitonic luminescence to the luminescence related to the tailing of the densityof states caused by potential fluctuations occurs at an irradiation dose around1 × 1014 cm−2 and 5 × 1012 cm−2 in nanorods and bulk layers, respectively. More than one order of magnitude enhancementof radiation hardness of ZnO nanorods grown by MOCVD as compared to bulk layersis also confirmed by the analysis of the near-bandgap photoluminescence bandbroadening and the behavior of resonant Raman scattering lines. The resonant Ramanscattering analysis demonstrates that ZnO nanostructures are more radiation-hardas compared to nanostructured GaN layers. High energy heavy ion irradiationfollowed by thermal annealing is shown to be a way for the improvement of thequality of ZnO nanorods grown by electrodeposition and chemical bath deposition.