On-Chip Synthesis of Quasi Two-dimensional Semimetals from Multi-Layer Chalcogenides

Two-dimensional (2D) materials are pivotal for exploring quantum phenomena and advancing next-generation electronics. Commonly used methods for preparing 2D materials include bottom-up approaches like vapor-phase deposition, which transport precursors onto substrates for reaction, and top-down methods such as mechanical exfoliation to obtain atomically thin layers from bulk materials. Alternatively, thin crystalline, non-layered materials are often grown epitaxially, which is not substrate agnostic. Achieving substrate-independent synthesis of non-layered quasi-2D materials remains challenging despite these established methods.<br/>In this work, we report a templated and versatile on-chip synthesis approach for the formation of quasi-2D non-layered crystalline Kagome semimetals. This method involves a controlled transformation of a series of nanometer-thin layered vdW semiconducting chalcogenides (e.g. InSe) through reaction with the diffused metal atoms within the materials. We present the growth kinetics of this approach through a comprehensive set of experiments, varying the temperature and the chalcogenide flake thickness. Additionally, we analyze the transport properties of the quasi-2D Kagome semimetals, which exhibit two types of carriers and a low resistivity of ~ 45 μΩ cm at room temperature. Finally, we provide a pathway to construct high-performance 2D field-effect transistors (FETs) using our novel synthesis technique by creating a semimetal/semiconductor/semimetal heterostructure with intimate contacts, which offers not only improved DC performance but also mitigated parasitic capacitances for better AC performance.