Highly selective H2S gas sensor based on Cu-doped ZnO nanocrystalline films deposited by RF magnetron sputtering of powder target

• Cu doped ZnO thin films were synthesized using cost effective, in-house made powder target by RF magnetron sputtering.
• XRD and XPS studies confirmed the incorporation of Cu ions into the Zn lattice site.
• 2% Cu doped ZnO film showed high selectivity and sensitivity to H2S at an operating temperature of 250 °C.

Cu – doped ZnO (CZO) films were synthesized by RF magnetron sputtering of composite target prepared with powders of ZnO and copper. Crystalline nature, morphology and chemical/electronic composition of the films were investigated by X-ray diffraction (XRD), Atomic Force Microscopy (AFM) and X-ray photoelectron spectroscopy (XPS). XRD showed hexagonal wurtzite structure with strong c-axis orientation for both doped and undoped films. AFM study revealed uniform deposition of nanocrystallites and XPS confirmed the Cu incorporation into ZnO lattice. Further the H2S sensing properties of the CZO films were investigated at different operating temperatures and gas concentrations. While all the doped films were highly selective to H2S, 2% CZO film showed highest sensitivity at an operating temperature of 250 °C.