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.
Cite
@article{arxiv.2511.07151,
title = {Defect-Mediated Phase Engineering of 2D Ag at the Graphene/SiC Interface},
author = {Arpit Jain and Boyang Zheng and Sawani Datta and Kanchan Ulman and Jakob Henz and Matthew Wei-Jun Liu and Van Dong Pham and Wen He and Chengye Dong and Li-Syuan Lu and Alexander Vera and Nader Sawtarie and Wesley Auker and Ke Wang and Bob Hengstebeck and Zachary W. Henshaw and Shreya Mathela and Maxwell Wetherington and William H. Blades and Kenneth Knappenberger and Ursula Wurstbauer and Su Ying Quek and Ulrich Starke and Shengxi Huang and Vincent H. Crespi and Joshua A. Robinson},
journal= {arXiv preprint arXiv:2511.07151},
year = {2025}
}