Oxygen vacancies assisting green light sensing in Ga/Fe doped ZnO

Abstract

Faster, sensitive, cost-effective UV and visible photodetection is an important research area for making sensors. The comparison of the structural, vibrational and optical properties of a substituted sample with pure ZnO was studied. We investigated the photoresponse properties of defects in parent and Zn1-x(GaFe)x/2O (x=0.0468) for UV and visible light illumination. The ZnO nanopowders were synthesized using the sol-gel technique. The (002) peak tends to deviate towards higher theta with the addition of Ga3+/Fe3+. This indicates a variation of c-axis with Fe and Ga doping. Lattice parameter variation with co-doping is obtained by using GSAS software. Rietveld refinement of all samples showed changes in lattice parameters. From Raman spectra, the intensity of E2 high mode enhances with doping showing good crystallinity of co-doped ZnO. Thus, structural uniformity enhances with doping. The conductance increases due to varying defect states, verified from photoluminescence data analysis. Ga and Fe doping improve UV current of ZnO. We can see that the photocurrent increases from x=0 to x=0.0468. Effect of different wavelengths (450, 550 & 650 nm) of photons on surface conductivity of Zn1-x(GaFe)x/2O is investigated. The enhanced sensitivity with the incorporation of dopants for visible spectrum has great application for colour sensing materials. And least sensitivity for red colour shows photostability of the material. The native defects or trap states present in pure and Ga-Fe co-doped samples were investigated in detail by using PL study. The visible spectrum deep level intensity variation reveals enhancement in green emission following the CIE graph. The optical bandgap energy investigated using UV-Vis spectrum. The modification in bandgap energy supports the defects study obtained. © 2020 American Institute of Physics Inc.. All rights reserved.