Manufacturing of CuO@ZnO Nanoparticles Core-Shell for Enhancing Electrical Properties and Spectral Responsivity of Photodetectors

Zinc oxide nanoparticles (ZnO NPs), copper oxide nanoparticles (CuO NPs) and CuO@ZnO NPs as a colloidal core-shell solution were synthesized by laser ablation. A Nd:YAG laser with an energy of 700 mJ, a wavelength of 1064 nm and 200 pulses was used for the ablation process. The colloidal solution was deposited on porous silicon (PSi) using the drop-casting method. The PSi substrates were prepared by photoelectrochemical etching (PECE) on n-type (111) silicon wafers. The study investigated the influence on the electrical, optical, morphological and structural properties of the CuO NPs and ZnO NPs samples when they were converted into a core-shell, specifically for their use in photodetector applications. XRD analysis revealed the presence of CuO, ZnO and CuO@ZnO by diffraction peaks at different angles. According to the SEM images, the nanoparticles show randomly distributed spherical grains, while PSi exhibits a sponge-like structure. The core-shell shape is confirmed by TEM images, which show a dark inner region consisting of CuO NPs and a much lighter outer region consisting of the ZnO nanoshell. The optical properties of the CuO@ZnO NPs were investigated and a minimum energy gap of 2.8 eV was found. The CuO@ZnO NPs/PSi/n-Si photodetector showed improved current-voltage (J-V) characteristics, rectifying properties and remarkable sensitivity in the visible to near-infrared region compared to other photodetector samples. The fabricated photodetector confirmed improved quantum performance, especially in the visible spectrum. The work aims to synthesize CuO@ZnO core-shell nanoparticles by a laser ablation technique to improve the electrical properties and spectral response of photodetectors.