Abstract
Tin oxide (SnO_2) is widely used in metal-oxide-semiconductor for gas-sensing materials due to its unique physical and chemical properties. The grain size is one of the major influencing factors that determine the gas-sensing characteristics. In this work, a facile hydrolysis-oxidation-hydrothermal method is used to prepare the size-controllable SnO_2 quantum dots (QDs) of 4.7-8.9 nm, and the gas-sensing characteristics of the SnO_2 QDs sensors are evaluated by C_4H_(10), H_2 and C_2H_5OH at room temperature. The experimental results show that the resistance has a negative correlation with hydrothermal time, and the maximum response is obtained when the grain radius is comparable to the depletion layer width. A comprehensive model is proposed by considering all gas-sensing procedures of the receptor function, the transducer function and the utility factor. The sensor properties are formulated as functions of grain size, depletion layer width, film thickness, oxygen vacancy density, gas concentration, pore size as well as operating temperature. The present model provides a comprehensive mathematical interpretation of the size effects of SnO_2 from partial depletion to volume depletion.
NSTL
Elsevier