High performance CuS p-type thin film as a hydrogen gas sensor

In this study, CuS thin films with p-type behaviour were prepared using two solvent types: deionized water (S1) and deionized water mixed with ethanol (S2). The thin films were deposited onto substrates comprising glass slide, multilayer of ZnO/Cu/ZnO, ZnO nanorods and Poly(methyl methacrylate) (PMMA). XRD analysis revealed the presence of covellite-CuS phase and chalcocite-Cu2S phase with average crystallite sizes of 14.1 nm and 15.4 nm, respectively in S1 sample while only covellite-CuS phase with an average crystallite size of 11.6 nm was identified for S2. Morphological observations (SEM) showed smaller sized nanoplates in S1 compared to S2. The results from implementation of the two devices as hydrogen gas sensors revealed S1 exhibits better sensitivity (98.9% at 1000 ppm) and shorter response and recovery times (16 s and 34 s at 800 ppm, respectively) compared to S2 (sensitivity of 78.4% at 1000 ppm; response and recovery times of 35 s and 24.4 s at 1000 ppm, respectively). The sensitivity was found to increase with increasing gas concentration for both samples. It was inferred from the results that CuS thin film prepared with only deionized water (S1) has a higher H2 gas detection potential.