Rise in UV and blue emission and reduction of surface roughness due to the presence of Ag and Al in monocrystalline ZnO films grown by sol-gel spin coating

Abstract

ABSTRACT Highly transparent thin films of aluminium doped ZnO along with specific silver co-doping are deposited by sol-gel spin coating, which show preferred single orientation along (100) plane. Presence of Al dopant reduces, whereas co-doping with Ag improves crystallinity. Films show sharp absorption in near UV region and band gap observes minor shifts. UV and blue emission peaks are seen in the photoluminescence spectra. UV and blue emission peaks, respectively, demonstrate a fairly large i.e. 43% and 77% rise in the normalised intensity. Presence of Ag causes rise in UV peak because of enhanced excitonic recombination probability. Rise of blue emission intensity is ascribed to creation of Ag-Al interstitials. Surface roughness increases to 210.0 nm with Al increment into ZnO and drops drastically to 81.1 nm by Ag co-doping. Boundaries of nanostructures club together with rise in Al amount and thereafter Ag co-doping is seen to reduce the particle size.