Electrical performance of a nanocomposite diode based on palladium nanoparticles- and polyethyleneimine functionalized nitrogen-doped graphene quantum dots

A nanocomposite material comprising palladium nanoparticles (PdNPs) doped with polyethyleneimine (PEI)-functionalized nitrogen-doped graphene quantum dots (PEI N-GQDs) was synthesized and employed as an interlayer in an Ag/PdNPs/PEI N-GQDs/p-Si heterojunction configuration. The PdNPs/PEI N-GQDs nanocomposite was prepared through an aqueous reaction between PEI-functionalized N-GQDs and Pd(NO₂)₂·H₂O and characterized using FTIR, UV-Vis, TEM, XPS, and PL spectroscopy. The PL spectrum exhibited a broad emission centered at 580 nm (2.14 eV) with a near-infrared tail, indicating defect-assisted recombination and confirming the semiconducting nature of the nanocomposite. The Ag/PdNPs/PEI N-GQDs/p-Si diode displayed a rectification ratio of approximately 1.64 × 10² at ± 4 V, with barrier heights of 0.87, 0.76, and 0.68 eV obtained from thermionic-emission (TE), Cheung, and Norde methods, respectively. Energy band alignment analysis revealed that the rectifying behavior originates from the Ag/nanocomposite interface, forming a Schottky-type barrier, while a type-II staggered junction is established at the nanocomposite/p-Si interface, facilitating hole transport. These findings demonstrate the potential of PdNPs/PEI N-GQDs as an effective interlayer material for carbon-based nanoelectronic and optoelectronic devices.