Epitaxial growth of wafer-scale 2D superconductor single crystals by metal-organic chemical vapor deposition

Metallic two-dimensional (2D) transition metal dichalcogenides (TMDCs) are garnering significant attention for their ability to enhance device performance when used as 2D contacts with semiconducting 2D materials, as well as for their intriguing low-temperature properties, including superconductivity, magnetism, and charge density waves (CDWs). However, the advancement of both fundamental studies and practical applications has been hindered by challenges in synthesizing high-quality, large-area materials. In this work, we report the epitaxial growth of wafer-scale 2D superconducting TMDC single-crystal multilayers by metal-organic chemical vapor deposition (MOCVD). Our NbS₂ multilayer films achieve high wafer-scale uniformity and single crystallinity of 2H phase, as confirmed by AFM, Raman spectroscopy, SHG mapping, LEED and STEM measurements. This is enabled by a dual-precursor strategy that drives self-templated concurrent epitaxy on lattice-matched sapphire, which is further supported by a kinetic growth model. Devices fabricated from the NbS₂ film demonstrate superconductivity below a transition temperature of 3 K, consistent with a Berezinskii-Kosterlitz-Thouless (BKT) type superconducting phase transition, with an impressive yield of 95.1% and a resistance variation of only 12%. Additionally, we demonstrate the wafer-scale growth of superconducting NbSe₂ films (T_c = 5 K) via MOCVD. Our work underscores a versatile and scalable approach for synthesizing wafer-scale 2D superconductor single crystals, which is essential for their integration into next-generation TMDC-based electronic devices.