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@LiNbO 3 , 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@LiNbO 3 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@LiNbO 3 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@LiNbO 3 /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 × 10 12 Jones at 380 nm, respectively, for Au@LiNbO 3 /p-Si isotype heterojunction photodetector fabricated at 1.3 J/cm 2 laser fluence. The Energy band diagram of Au@LiNbO 3 core–shell nanoparticles under illumination is constructed.