Effect of boron doping on the structural, optical and electrical properties of ZnO nanoparticles produced by the hydrothermal method

Abstract

The effect of boron doping with 0–11 at% concentration on structural, optical and electrical properties of zinc oxide nanopowder synthesized by a hydrothermal method has been reported. We have performed X-Ray Diffraction (XRD), Scanning Electron Microscopy (SEM), optical, Hall and resistivity measurements on the samples. XRD results reveal that all B doped ZnO nanopowders have single phase hexagonal (Wurtzite) structure without any impurity. But the positions of main diffracted peaks of ZnO shifted slightly towards small (2θ) angle and grain size decreases from 60.75 nm to 34.34 nm with an increase of B doping concentrations. SEM analysis indicates that the doping concentration of B affected the surface morphology of ZnO nanostructures. Optical properties were examined by UV–vis absorption/diffuse reflectance spectroscopy. The optical band gap of Zn1−xBx O nanostructures increased from 3.27 eV to 3.30 eV with increasing doping from x=0 to x=0.11. The role of doping concentrations of B on the transport properties was searched by temperature dependent Hall measurements in 180–350 K temperature range. The carrier concentration of the samples increased from 0.11×1014 cm−3 to 4.08×1014 cm−3, the Hall mobility decreased from 5.61 cm2 V−1 s−1 to 1.22 cm2 V−1 s−1 and electrical resistivity decreased from 10.89×104 Ω cm to 1.25×104 Ω cm with the increase of the B doping concentrations at room temperature. The electrical resistivity is observed to decrease with both the increase in dopant concentration and the temperature in the range of 180–350 K.