High-quantum efficiency of Au@LiNbO3 core-shell nano composite as a photodetector by two-step laser ablation in liquid

Hybrid and novel Gold core Lithium niobate shell (Au@LiNbO3, Au@LN) nanoparticles were prepared for the first time by two steps of laser ablation in liquid at different laser fluences. X-ray diffraction, Raman scattering, UV-Visible spectrophotometer, and transmission electron microscope were used to investigate the structural and optical properties of the core-shell nanoparticles. The X-ray diffraction results show that the synthesized Au@LiNbO3 core-shell nanoparticles are polycrystalline in nature, with 2 J/cm(2) being the highest crystallinity nanoparticles. Transmission electron microscope studies show the formation of core-shell morphology and the size of the core and shell thickness depends on the laser fluence. The optical absorption of nanocomposites showed the presence of a plasmon peak related to gold (Au) at 500 nm. The energy gap of Au@LiNbO3 increased from 3.5 to 3.8 eV as laser fluence increased. The presence of active phonons was revealed by Raman results. The current-voltage characteristics of Au@LiNbO3/Silicon (Si) heterojunction in the dark and illumination are studied as a function of laser fluence. The maximum responsivity and detectivity are 0.69 A/W and 6.5 x 10(12) Jones at 380 nm, respectively, for Au@LiNbO3/p-Si isotype heterojunction photodetector fabricated at 1.3 J/cm(2) laser fluence. The Energy band diagram of Au@LiNbO3 core-shell nanoparticles under illumination is constructed.