Enhanced optical and electrical properties of antimony doped ZnO nanostructures based MSM UV photodetector fabricated on a flexible substrate

Undoped Zinc oxide (ZnO) and Antimony doped Zinc Oxide (Sb: ZnO) nanostructures (nanocones and nanoflakes) with different doping concentrations of Sb (3 at%, 6 at% and 9 at%), were grown on flexible (ITO/PET) substrate using a simple hydrothermal method. The seed layer of ZnO was prepared using sol-gel method, which was then used as the base to grow Sb: ZnO nanostructures by hydrothermal method. Structural, optical and electrical characteristics of undoped and Sb: ZnO nanostructures were studied for three different doping concentrations of Sb. The structural and morphological studies of the prepared samples were carried out using XRD and FESEM. EDAX was used for elemental analysis. The XRD spectrum reveals ZnO wurtzite structures. The FESEM results clearly indicate that there was no change in morphology of ZnO nanostructures with the substitution of Sb in ZnO lattices. The optical studies were performed on all samples using UV-Vis spectroscopy. It was observed that the transmission and the bandgap energy reduced with an increase in doping concentration. IV curves were plotted using an impedance analyzer. The samples were studied under dark conditions and under UV light of 365 nm. A monotonic increase in electrical conductivity was observed with increase in doping concentration, asserting the fact that addition of Sb to ZnO increases the conductivity of the samples, making Sb: ZnO a good candidate for photodetection. The responsivity and efficiency of the device under UV illumination of 365 nm were found to be 2.62 A/W and 893.35% respectively, with the highest values being observed for 9 at% of Sb doping.