Interaction of metal nanoparticles with a semiconductor in surface-doped gas sensors

A capacitance response of semiconductor sensors fabricated on the basis of thin NiO and SnO2 films with noble-metal nanoparticles deposited on their surface was analyzed. This response was shown to appear due to the solid-phase metal-semiconductor reaction accompanied by the formation of a boundary layer with a fairly high density of surface electron states in its band gap. The chemisorption field effect (the change in work function of the metal after inlet of gases) observed in the capacitance gas sensors not only forms the basis for the sensitive and prompt method of analysis but also represents the basic functional phenomenon responsible for their capacitance response.