PREPARATION AND CHARACTERIZATION OF ZnO: SnO2 NANOCOMPOSITE THIN FILMS ON POROUS SILICON AS H2S GAS SENSOR

Abstract

Mixed nanocomposite thin films of ZnO-SnO2 were prepared by chemical spray pyrolysis. It deposited on glass and porous silicon substrates at 400 C°. The structure properties of the sensor material were analyzed by XRD and AFM. The results obtained that the films are polycrystalline with nano grain size. the optical transmission was decreased while the optical energy gap was increased with increasing of SnO2 ratio. The sensor response was estimated by changing in the electrical resistance of the sensor films with 25% H2S gas of different temperatures. The mixed oxide sensor gives a sensitivity of H2S gas three times greater than the sensitivity of a single SnO2 gas sensor. The higher sensitivity of mixed oxide is 92% on porous silicon at 200C° operating temperature ,with response time of 16s and recovery time 28s. The high response of ZnO-SnO2 nanocomposite sensor is an indicator of a high efficiency of H2S gas sensing.