Study of humidity properties of zinc oxide modified porous silicon

In this paper, we discussed the humidity sensing behavior of Zinc Oxide modified porous silicon (ZnO/PS) composite structure. The porous silicon substrates were prepared by the electrochemical etching process first. Then, by sol-gel technique, it is possible to obtain a uniform Zinc Oxide films on the porous silicon substrates. The electrical conductivities of the porous silicon and Zinc Oxide modified porous silicon structures under different humidity levels were measured. Our study indicate that the modification of porous silicon by sol-gel Zinc Oxide increase the sensitivity and shorten the response time to the relative humidity, probably due to the increment of the specific surface area of the porous silicon. The other parameters, such as the concentration of zinc oxide precursors, which can affect the sensing performance, were also discussed. Therefore, the Zinc Oxide modified porous silicon composite structure studied is potential to develop the humidity sensor with high performance.