Thickness effect on sensing properties of pure Cu2O thin films under sub-ppm O3 levels

Abstract

The sub-ppm ozone (O3) sensitivity of pure cuprous (Cu2O) thin films based sensors have been investigated by utilizing conductivity measurements at different temperatures varies from 150 to 200 °C. The structural and morphological properties of Cu2O sensitive layers have been investigated by the scanning electron microscope (SEM) and x-ray diffraction (XRD) respectively. The detection properties of Cu2O layers have been strongly altered by the electrode geometries and sensitive layer thickness. The sensors’ responses and structural investigations revealed that the ozone sensitivity has improved with the increase in the degree of crystallinity along the preferential direction (111). Ab-initio calculation shows that O3 adsorption mechanism could be semi- dissociative of O3 molecule on the Cu2O (111) surface, giving O2 molecule remaining in interaction with the surface and an adsorbed oxygen Oads.