The Effect of the Number of Laser Pulses on Some Physical Properties Affecting Gas Sensitivity of CdO Thin Films Prepared by PLD Method

Abstract

In this research, thin films of cadmium oxide (CdO) were manufactured using pulse laser deposition (PLD) technology on glass substrates under pressure of (0.001 mbar) at room temperature by a laser power effect (800mj/cm) with a number of different laser pulses (N= (150-200-250 and 300)). The optical and synthetic properties of thin cadmium oxide films were studied, as well as their gas sensitivity. The optical properties of thin films were analyzed and studied using absorption spectra (UV-VIS) UV-Visible measurements show that CdO films of different thicknesses have a direct permissible transition with the band gap between (2.51) and (2.22) eV before annealing and after annealing the band gap decreases to become between (2.44) and (2.06). As for synthetic properties, they were analyzed and studied through X-ray diffraction patterns which showed the thin films are multicrystalline the grain size increase with the increase in the number of pulses from (100) pulse to (300) pulse gradually as for the effect of annealing, it also led to an increase in the size of the particles. While gas sensor properties were studied using static gas sensor system. The results of gas sensor showed that the increase in operating temperature improves film sensitivity. the maximum sensitivity of the pure CdO film to gas (NO2) was found to be 46.16% at 200°C and the number of pulses was (150). After annealing, the gas sensitivity decreased to was (34.25%) for (150) pulses.