Defect-Mediated Phase Engineering of 2D Ag at the Graphene/SiC Interface

Abstract

Atomically thin silver (Ag) films offer unique opportunities in plasmonic, quantum optics, and energy harvesting, yet conventional growth methods struggle to achieve structural control at the monolayer limit. Here, we demonstrate phase-selective synthesis of large-area, crystalline 2D Ag films via defect-engineered confinement heteroepitaxy (CHet) at the epitaxial graphene/silicon carbide (EG/SiC) interface. By tuning graphene growth and post-growth defect introduction, two distinct Ag phases are achieved with disparate properties: a nearly commensurate Ag(1) lattice stabilized by vacancy and line defects in epitaxial graphene, and a denser Ag(2) phase preferentially grown with sp3-rich zero-layer graphene. Structural and spectroscopic characterization confirm lattice registry with the SiC substrate, while theoretical calculations reveal a thermodynamic preference for Ag(2) but an easier nucleation for Ag(1). Both phases are found to be semiconducting, with the Ag(2) phase exhibiting slightly enhanced n-doping of graphene. Notably, nonlinear optical measurements reveal a three-order magnitude difference in second-order susceptibility between the two phases, demonstrating promise for phase-tunable 2D metals in reconfigurable optoelectronic and metamaterial platforms.

References in corpus (23)

• Optimized norm-conserving Vanderbilt pseudopotentials
• Probing the Nature of Defects in Graphene by Raman Spectroscopy
• Optimization Algorithm for the Generation of ONCV Pseudopotentials
• Optical Separation of Mechanical Strain from Charge Doping in Graphene
• Quasi-free Standing Epitaxial Graphene on SiC by Hydrogen Intercalation
• BerkeleyGW: A Massively Parallel Computer Package for the Calculation of the Quasiparticle and Optical Properties of Materials and Nanostructures
• Electronic structure of epitaxial graphene layers on SiC: effect of the substrate
• Truncation of Periodic Image Interactions for Confined Systems
• The Role of Electron-electron Interactions in Graphene ARPES Spectra
• Direct Observation of Superconductivity in Calcium-Intercalated Bilayer Graphene by in situ Electrical Transport Measurements
• Electronic decoupling of an epitaxial graphene monolayer by gold intercalation
• The mechanism of caesium intercalation of graphene
• Plasmonics in Atomically-Thin Crystalline Silver Films
• Li-intercalated Graphene on SiC(0001): an STM study
• Unexpected Near-Infrared to Visible Non-linear Optical Properties from Two-Dimensional Polar Metals
• Atomic and electronic structure of monolayer graphene on 6H-SiC(000-1)(3 x 3) : a scanning tunneling microscopy study
• Momentum microscopy of Pb-intercalated graphene on SiC: charge neutrality and electronic structure of interfacial Pb
• Epitaxial Graphene Growth on SiC Wafers
• Large-Area Intercalated 2D-Pb/Graphene Heterostructure as a Platform for Generating Spin-Orbit Torque
• Graphene as a Mechanically Active, Deformable Two-Dimensional Surfactant
• Ultraconfined plasmons in atomically thin crystalline silver nanostructures
• Confined monolayer Ag as a large gap 2D semiconductor and its momentum resolved excited states
• Point defects and their dynamic behaviors in silver monolayer intercalated between graphene and SiC