Laser ablation of Au–CuO core–shell nanocomposite in water for optoelectronic devices

Abstract

Core–shell gold–copper oxide Au–CuO nanocomposites were synthesized using laser ablation of CuO target in colloidal solution of Au nanoparticles (NPs). The effect of laser fluence on the structural, morphological, electrical, and optical properties of Au–CuO nanocomposites was investigated using x-ray diffraction (XRD), atomic force microscope (AFM), scanning electron microscope (SEM), transmission electron microscope (TEM), photoluminescence (PL), Fourier transformed infrared spectroscopy (FTIR), Hall measurement, and UV–vis spectroscopy. X-ray diffraction results confirm the formation of polycrystalline Au–CuO NPs with monoclinic structure. The optical energy gap for CuO was 4 eV and for the Au–CuO core–shell nanocomposites was found to be in the range of 3.4–3.7 eV. SEM and TEM investigations revealed that the structure and morphology of Au–CuO core–shell nanocomposites were strongly depending on the laser fluence. A formation of Au–CuO nanospheres and platelets structures was observed. The photoluminescence data showed an emission of broad visible peaks between 407 and 420 nm. The effect of laser fluence on the dark and illuminated I–V characteristics of Au–CuO/n-Si heterojunction photodetectors was investigated and analyzed. The experimental data demonstrated that the photodetector prepared at optimum laser fluence exhibited photosensitivity of 0.6 AW−1 at 800 nm.