Engineering of MIS interfaces using 2D gold nanoparticle monolayers for improved nano-Schottky tunneling diodes

Abstract

Schottky diodes are a fundamental component of semiconductor technology, primarily due to their distinctive rectifying behavior at metal–semiconductor (M–S) interfaces. This research investigates the potential of nanoscale Schottky-type contacts to overcome conventional CMOS scaling limitations by leveraging enhanced quantum tunneling and thermionic emission across engineered interfaces. A novel metal–insulator–semiconductor (MIS) diode architecture is developed by integrating a two-dimensional (2D) monolayer of gold nanoparticles (Au-NPs) onto an n-type silicon (n-Si) substrate, separated by a thin SiO₂ insulating layer. The study systematically explores the influence of Au-NP diameters (20 nm, 30 nm, and 40 nm) on charge transport mechanisms. Nanoparticle monolayers were fabricated via drop-casting under an external electric field to ensure uniform alignment. Structural characterization confirmed well-distributed and high-quality monolayers. Electrical measurements revealed a strong size-dependent behavior: the 20 nm Au-NP-based diode exhibited the highest reverse-bias tunneling current (–0.2234 mA at –3.6 V), the lowest contact resistance, and the smallest effective contact area due to enhanced electric field localization. Diodes with larger particles showed reduced tunneling efficiency and higher resistive losses. COMSOL simulations supported the experimental findings, demonstrating that smaller Au-NPs generate higher electric field intensities (4.15 × 10⁸ V/m) at the interface, significantly boosting tunneling probability. These results demonstrate that Au-NP monolayers can be precisely engineered to enhance charge transport across MIS junctions, offering a scalable pathway for high-performance nanoelectronic and optoelectronic devices.