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arXiv · 2511.07151

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

Arpit Jain·Boyang Zheng·Sawani Datta·Kanchan Ulman·Jakob Henz·Matthew Wei-Jun Liu·Van Dong Pham·Wen He·Chengye Dong·Li-Syuan Lu·Alexander Vera·Nader Sawtarie·Wesley Auker·Ke Wang·Bob Hengstebeck·Zachary W. Henshaw·Shreya Mathela·Maxwell Wetherington·William H. Blades·Kenneth Knappenberger·Ursula Wurstbauer·Su Ying Quek·Ulrich Starke·Shengxi Huang·Vincent H. Crespi·Joshua A. Robinson
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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.

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Arpit Jain, Boyang Zheng, Sawani Datta, Kanchan Ulman, Jakob Henz, Matthew Wei-Jun Liu, Van Dong Pham, Wen He, Chengye Dong, Li-Syuan Lu, Alexander Vera, Nader Sawtarie, Wesley Auker, Ke Wang, Bob Hengstebeck, Zachary W. Henshaw, Shreya Mathela, Maxwell Wetherington, William H. Blades, Kenneth Knappenberger, Ursula Wurstbauer, Su Ying Quek, Ulrich Starke, Shengxi Huang, Vincent H. Crespi, Joshua A. Robinson. 2025-11-10. Defect-Mediated Phase Engineering of 2D Ag at the Graphene/SiC Interface. https://doi.org/10.1002/adma.74689

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