THE AMMONIA VAPORS INFLUENCE ON THE ELECTRICAL CHARACTERISTICS OF NANOSIZED TIN DIOXIDE FILMS OBTAINED USING A POLYMER

In the presented paper the effect of ammonia vapors on the electrical properties of nanosized tin dioxide films obtained using polymers was investigated to assess the possibility of their use as an ammonia sensor’s sensitive element at room temperature. Ammonia vapor leads to a decrease in the conductivity of the studied SnO2 films. This is due to the fact that the adsorbed ammonia molecules increase the height of the intergranular potential barriers, and the surface shut-off bend of the energy bands. The main role in this is played by the processes of physical adsorption of ammonia molecules. The sensitivity of the films to ammonia vapor is in the range of 0.35-0.63 and reaches a maximum at a voltage of 300 V. The processes of adsorption and desorption take place in two stages and are reversible, as evidenced by the calculated time constants of adsorption and desorption.