Large-area, freestanding single-crystal gold of single nanometer thickness

• DOI: 10.48550/arxiv.2311.07858
• Publication Date: 2023-01-01
• Authors: Pan, Chenxinyu; Tong, Yuanbiao; Qian, Haoliang; Krasavin, Alexey V.; Li, Jialin; Zhu, Jiajie; Zhang, Yiyun; Cui, Bowen; Li, Zhiyong; Wu, Chenming; Wang, Zhenxin; Liu, Lufang; Li, Linjun; Guo, Xin; Zayats, Anatoly V.; Tong, Limin; Wang, Pan
• Keywords: FOS: Physical sciences; Physics - Optics; Optics (physics.optics)

Two-dimensional single-crystal metals are highly sought after for next-generation technologies. Here, we report large-area (>10^4 μm2), single-crystal two-dimensional gold with thicknesses down to a single-nanometer level, employing an atomic-level-precision chemical etching approach. The ultrathin thickness and single-crystal quality endow two-dimensional gold with unique properties including significantly quantum-confinement-augmented optical nonlinearity, low sheet resistance, high transparency and excellent mechanical flexibility. By patterning the two-dimensional gold into nanoribbon arrays, extremely-confined near-infrared plasmonic resonances are further demonstrated with quality factors up to 5. The freestanding nature of two-dimensional gold allows its straightforward manipulation and transfer-printing for integration with other structures. The developed two-dimensional gold provides an emerging platform for fundamental studies in various disciplines and opens up new opportunities for applications in high-performance ultrathin optoelectronic, photonic and quantum devices.