Electrical and gas-sensing properties of nano-sized Os-doped sol-gel derived SnO2 thin films

Undoped and osmium-doped tin oxide thin films have been deposited by the sol-gel spin-coating method. The electrical properties of the as-prepared polycrystalline Sn02 films have been analysed by measuring their resistivity, Hall mobility, type and density of charge carriers as a function of the osmium doping in order to understand the role of osmium in the electrical transport mechanism of the films and in the sensitivity to methane of the Os-doped Sn02, samples. The Hall effect and resistivity measurements have been carried out in 100÷500 K temperature range both in vacuum and in air. The results have been investigated according to grain boundary scattering mechanism and used to explain the better sensing properties towards CH4, at low temperature, of the Os-doped Sn02 thin films as compared with the undoped ones.