On-Chip Synthesis of Quasi-2D Semimetals from Multi-Layer Chalcogenides

Reducing the dimensions of materials from three to two, or quasi-two, provides a fertile platform for exploring emergent quantum phenomena and developing next-generation electronic devices. However, growing high-quality, ultrathin, quasi2D materials in a templated fashion on an arbitrary substrate is challenging. Here, the study demonstrates a simple and reproducible on-chip approach for synthesizing non-layered, nanometer-thick, quasi-2D semimetals. In one implementation, this method starts with thin semiconducting InSe flakes of below 20 nm in thickness with nickel deposited on top, followed by a low-temperature annealing step that results in a controlled transformation of the layered InSe to a non-layered, crystalline semimetal via reaction with the laterally diffusing nickel. Atomic resolution microscopy reveals the transformed semimetal to be Ni₃In₂Se₂ with a Kagome-lattice structure. Moreover, it is demonstrated that this synthesis method is generalizable by transforming 2D layered chalcogenides such as SnS and SnSe employing Ni and Co to non-layered semimetals, paving the way for engineering novel types of devices.