Comparative study on hydrothermally synthesized undoped and Vanadium doped Zinc Oxide nanorods for nanoelectromechanical systems low-frequency accelerometer application

Abstract

Lead-free undoped and Vanadium (V) doped Zinc Oxide (ZnO) nanorods were grown on rigid Fluorine-doped Tin Oxide substrates using a simple hydrothermal method. Poly(3,4-ethylenedioxythiophene) polystyrene sulfonate was coated on the grown nanorods to form a p-n junction. The optical, crystalline and morphological analysis were done using X-ray diffraction, Ultraviolet-Visible spectroscopy, Field Emission Scanning Electron Microscope and Spectrofluorescence. The decrease in bandgap from 3.1 eV (undoped) to 3 eV (V doped) showed increased conductivity. Current-Voltage analysis depicted an improvement in the electrical properties of V doped device in terms of a low turn-on voltage, rectification ratio and reverse leakage current density. The RC time constant was analyzed using Impedance analysis. A decrease in RC time constant value and internal resistance of 0.06 msec and 1.61 kΩ respectively for V doped ZnO device compared with undoped one showed an improved piezoelectric property. The maximum output voltages of 1.6 V and 1.9 V for 9 Hz and 1 g input respectively were observed in the V doped device. The sensitivity of undoped and V doped device was 1.71 V/g and 1.93 V/g respectively. It is evident that ~12.9% of improved sensitivity is obtained when V is doped into ZnO nanorods.