Influence of Charge Carriers Concentration and Mobility on the Gas Sensing Behavior of Tin Dioxide Thin Films

Abstract

In order to investigate function of carrier behavior on gas-sensing properties, tin oxide-based films with different carrier concentration and mobility were obtained, by magnetron sputtering from the powder target, which was followed by further oxygen-management though the annealing treatment. The microstructure, surface morphology, electrical properties and gas sensitivity were characterized by XRD, Raman spectrum, photoluminescence spectrum, atomic force microscope, the hall effect system and electrochemical workstation, respectively. The results showed that all SnO2-based films had a tetragonal rutile phase with (101) preferred orientation. The introduction of fluorine and regulation of oxygen vacancies tuned carrier concentration from 1015/cm3 to 1021/cm3 and mobility from 102 cm2/V·s to 10−1 cm2/V·s. The decreasing carrier concentration as well as increasing mobility had a positively important function to improve the sensitivity of SnO2-based films. The air-annealed SnO2 film with lowest carrier concentration had a maximum sensitivity of R = 5.0, while vacuum-annealed SnO2:F film with the highest carrier concentration being the minimum sensitivity. This puts forward a novel reference for the design and application of SnO2-based gas sensing films.