Efficient UV photosensitive and photoluminescence properties of sol–gel derived Sn doped ZnO nanostructures

Abstract

In the present work, we report on the UV photosensitivity and photoluminescence properties of Sn-doped ZnO nanostructures fabricated by sol–gel method. The influence of Sn (0, 2 and 5 at.%) on structural, optical and ultraviolet photoconductivity properties has been investigated by X-ray diffraction (XRD), scanning electron microscopy, photoluminescence (PL) and photoconductivity measurements. As evident from XRD, the doping of Sn has a significant impact on the structure of ZnO nanostructures. The energy dispersive X-ray (EDS) analysis for 2 at.% Sn doped ZnO confirms the evidence of Sn in ZnO nanoparticles (NPs). PL spectra of undoped and Sn-doped ZnO samples have strong defects related visible emission, including violet emission at ∼418 nm, blue emission at ∼445 nm, blue–green emission ∼481 nm and green emission ∼525 nm. The introduction of defect levels upon Sn doping facilitates the carrier conduction under UV illumination (λ = 365 nm). Again the extent of Sn is found to affect the UV photoconductivity of nanostructures owing to the increment of resistance of ZnO at higher doping concentration. The variation of photoconductivity of ZnO with Sn concentration is highlighted in terms of appropriate scheme and justifications. Better understanding of the photoconductivity process of ZnO nanostructures upon chemical doping will be useful for the fabrication of realistic optoelectronics devices.