Synthesis and characterization of ZnO nanocrystal line for gas sensor application

Abstract

In this research, nanostructure of ZnO film has been fabricated by spraying 0.2M concentration of Zinc salt solution on glass substrate. The Zinc solution was prepared by solves 4.389908g of the Zinc salt in 100 mL of isopropyl alcohol C3H9O. In order to obtain the best optimization in their optical properties via the annealing effect, these films were treated thermally at different temperatures (RT, 200, 300 and 400). Then AFM and XRD tests are employed to examine the structure. According to X-ray diffraction patterns, the structure of all ZnO films is polycrystalline with hexagonal wurtizte structure and preferential orientation in the (002) direction. It also turns out that the annealing process has led to increase the high of the peaks of the x-ray pattern tests which means the structure has been improved. As for the surface morphology, the Atomic Force Microscope (AFM) test results are shown there is uniform distribution of homogeneous with columnar nanostructure grains. The band gap varies between (3.2-3.37 eV) and tendency to rise with annealing temperature have been observed through the optical measurement. The sensing tests showed that linear response with increasing the gas concentration and, the annealing treatment gave rise to the sensitivity and more selectivity for NO2 gas. Moreover, the best sensing performance in term of sensitivity and selectivity has been absorbed by ZnO film that was treated by 300 oC annealing temperature.