Substrate Critical Effect on the Structural and H2 Gas Sensing Characteristics of Solution-Processed Zn0.075Cu0.025O Films

In this study, we report the synthesis of Zn0.075Cu0.025O films by chemical bath deposition to determine the effect of substrate (glass slide or ZnO seed layer) on the structural and H2 gas sensing properties of the produced films. The crystal phase, structural topography, surface morphology and functional groups of the as-synthesized films as well as H2 gas sensing properties were investigated. Although both films have a hexagonal wurtzite structure, ZnO seed layer-based Zn0.075Cu0.025O film is more crystalline than glass slide-based Zn0.075Cu0.025O films. ZnO seed layer-based Zn0.075Cu0.025O films exhibited much more nanorod and less nanosphere forms compared to glass slide-based Zn0.075Cu0.025O films. EDX analysis and Raman spectra of both samples confirmed the presence of defects in Cu:ZnO samples. ZnO seed layer-based sensors showed higher response (140%) and lower operating temperature (80°C) compared to glass slide-based sensors (87% response and 140°C operating temperature). The most important thing to note here is that the fabricated sensors exhibited high response at room temperature. The responses at room temperature was found as 46% and 23% for the ZnO seed layer-based and glass slide-based sensors, respectively. Sensors operating at room temperature are especially important for commercial applications.