Short communicationEffect of the seed layer on surface morphology and humidity sensing property of CoTiO3 nanocrystalline film

CoTiO3 nanocrystalline film with enhanced humidity sensing property has been prepared via a two-step method. A nanostructured CoTiO3 seed layer was firstly grown on silicate substrate by sol-gel process, and another CoTiO3 layer was subsequently deposited on the seed layer by RF magnetron co-sputtering using TiO2 and Co2O3 targets. The influence of seed layer on the microstructure and humidity sensing property of the CoTiO3 film was investigated, it was found that the seed layer facilitates the intrinsic growth of CoTiO3 grain and improves the crystallinity. Meanwhile, the surface morphology changes from brick-like grain type to a pebble-like pattern. The uniformity and alignment of the grains are both strongly related to the underneath CoTiO3 seed layer. The as-prepared CoTiO3 multilayer displayed enhanced humidity sensing properties such as the sensitivity to 95%RH reached to 41.9. The response time and recovery time was dramatically shortened, from 50 s for the seed layer to 5 s for the multilayer.