Fabrication and properties of ZnO nanorods on silicon nanopillar surface for gas sensor application

Abstract

Zinc oxide (ZnO) nanorods are fabricated on the silicon nanopillar surface for gas sensor application. The silicon (Si) nanopillars with aspect ratio 5, average diameter from 200 to 400 nm, and the height from 1 to 2 µm are made by cesium chloride self-assembly lithography and inductively coupled plasma dry etching. The ZnO nanorod arrays grow on the Si nanopillar surface by hydrothermal method. As the growth time increases, the ZnO nanorods become stronger, and the space between the adjacent Si nanopillars become smaller until fully filled. The SEM images show that 60 min is the just growth time, which the ZnO nanorods on Si nanopillars surface have the largest aspect ratio. The XRD curves indicate that the ZnO nanorods both grown on planar and nanopillar surface are crystal in nature. For the gas sensing performance with 500 ppm ethanol at 250 °C, the response of the ZnO nanorod-Si nanopillar based gas sensor has an increase of 29% compared to that of the ZnO nanorod-planar Si one.