Van der Waals Epitaxy of Large-Area and Single-Crystalline Gold Films on MoS₂ for Low-Contact-Resistance 2D–3D Interfaces

Large-area and single-crystalline gold films with (111) orientation are grown on MoS₂ surfaces at 400 °C. Superior crystalline quality and continuity are observed on MoS₂ over the films grown on mica and sapphire substrates through the analysis of X-ray diffraction (XRD), atomic force microscope (AFM), and cross-sectional transmission electron microscope (XTEM). Even at the atomic scale, no defect or stacking fault is observed at the Au/MoS₂ interface. Furthermore, the domination of flat islands at the initial stage of film growth suggests that gold atoms can diffuse easily at the MoS₂ surface. All the evidence indicates that MoS₂ serves as an ideal substrate of van der Waals epitaxy to grow a 3D crystal on a 2D material. Through the integration of 2D–3D crystals and 2D–3D interfaces, it may lead to the next-generation electronic or optoelectronic devices as well as the applications in plasmonics, molecular sensing, and surface sciences.