Sub-10 nm metal nanogaps with high SERS performance via a novel conformal coating process

Abstract Metallic nanogaps enables inducing the strong coupling between neighboring metal structures, resulting in a great field enhancement in the gap. Therefore, it is crucial fundamental building blocks for nanoelectronics and nanophotonics. Moreover, the electromagnetic field enhancement of the tiny gap increases rapidly with the decrease of gaps size. Naturally, enables better device performance with higher field enhancements. However, as the size of nanogaps reduced to the sub-10 nm scale, the fabrication of metallic nanogaps faced with great challenges, including the decrease in uniformity, repeatability and stability of the fabricating process due to various manufacturing and physical constraints. Thus, how to further reduce the size of metal nanogaps for higher device performance has become a key issue in this field. In this work, we propose and demonstrate a novel approach to fabricate sub-10 nm metal nanogaps by coating a conformal ultrathin oxide film via atomic-layer deposition. The method can fabricate sub-10 nm gap in dense metal-nanostructure arrays with high stability, reliability and uniformity, which provides a reliable technical for the fabrication and application of high-performed metallic nanogap structures and devices.