On the Material of a Sensing Element Based on Tin Dioxide for a Gas Sensor

Using the ion-beam sputtering of a composite target in an atmosphere of argon and oxygen, films based on tin dioxide with the addition of yttrium oxide are obtained. It is found that the content of the yttrium additive varies from 0.4 to 6.2 at %. It is determined that the surface roughness decreases with an increase in the addition of yttrium in films. Using a high-resolution transmission electron microscope (HRTEM), an image of the microstructure of the Sn–(5 at %)Y–O film is obtained, on which grains with a size of 5 nm are distinguishable. The roughness data coincide with the data obtained using an electron microscope. The surface resistance of the films increases with an increase in the content of the yttrium additive. The electrophysical parameters of the films after their crystallization are determined using the Hall effect. The mobility of charge carriers in the films increases, and the concentration of charge carriers decreases with an increase in the content of the additive. The gas sensitivity of films to ethanol vapors in air (3000 ppm) is studied for films with a content of 2.8 and 3.6 at % yttrium. It is found that an increase in the content of yttrium contributes to an increase in the gas sensitivity.