Synthesis and Characterization of Cd1-xZnxS Composite Thin Films for Gas Sensing Application

Abstract

The Cd1-xZnxS composite films of (x=0, 0.25, 0.5, 0.75, and 1) have been synthesized by laser deposition technique with laser pulse energy of Q-Switched Nd:YAG laser (1064 nm). lasing energy of (900 mJ) with fixed number of pulses of (700 p) and pulse duration rate of (6 Hz) have been used in the deposition. The operation temperature effect in the range of (25-250 °C) on the sensitivity of composite films has been achieved with optimizing the operation temperature to the lowest possible value. Two different reaction gases were used to measure the sensing effect of samples, the nitrogen dioxide (NO2) as oxidant gas and ammonia (NH3) as reducing gas. The sensitivity of the films has been increased as the operation temperature increasing up to 200 °C, and the electric resistance has been decreased as the operation temperature increasing, where the temperature activates the surface of the films to response of NO2 gas. The sensitivity of NO2 gas of the Cd0.75Zn0.25S film has a higher sensitivity from the others samples. On the other hand, the sensitivity of NH3 gas of all films has been decreased as the operating temperature increasing and the Cd0.25Zn0.75S film has a high sensitivity (292%) at room temperature.