Worm like zinc oxide nanostructures as efficient LPG sensors

Multi-layered films of zinc oxide (ZnO), prepared using sol–gel spin-coating method, were used to study the response on exposure to liquefied petroleum gas (LPG). The X-ray diffraction (XRD) pattern of the thin films showed preferred orientation of the crystallites along the c-axis. Surface morphology studies using scanning electron microscopy (SEM) reveal a wrinkled surface with a worm like appearance for the film thickness varying from 85 nm to 419 nm. The films of different thickness were exposed to LPG and sensing characteristics were recorded using electrical methods. The ZnO thin films showed good sensitivity toward LPG at optimum temperature of 200 °C with sensitivity strongly depending on the number of layers deposited. The sensing characteristics were further correlated with the microstructure of the thin films investigated using atomic force microscopy (AFM).