Structural, raman, photo-luminescent and optical investigation of sol–gel derived Co, Al and Ni doped ZnO thin films

Abstract

In this work, sol–gel spin coating route was utilized for the synthesis of undoped, Co-doped, Al-doped, and Ni-doped thin films of ZnO. XRD results show that deposited thin films possess a hexagonal lattice with preferential c-axis orientation. A reduction in lattice constants was observed owing to the substitution of Zn2+ ions by lower radius doping ions Co2+, Al3+, and Ni2+. The effect of doping is to reduce the crystallite size. Raman spectra show a characteristic peak of hexagonal ZnO at 439 cm−1. PL spectrum of all films demonstrates a UV emission ascribed to near band edge transition and a green emission band. All thin films with the transmission in visible regions above 86% are highly transparent. The doping element influenced the band gap of doped thin films.