Growth of Single-Crystalline Cadmium Iodide Nanoplates, CdI 2 /MoS 2 (WS 2 , WSe 2 ) van der Waals Heterostructures, and Patterned Arrays

Two-dimensional layered materials (2DLMs) have attracted considerable recent interest for their layer-number-dependent physical and chemical properties, as well as potential technological opportunities. Here we report the synthesis of two-dimensional layered cadmium iodide (CdI ) nanoplates using a vapor transport and deposition approach. Optical microscopy and scanning electron microscopy studies show that the resulting CdI nanoplates predominantly adopt hexagonal and triangular morphologies with a lateral dimension of ∼2-10 μm. Atomic force microscopy studies show that the resulting nanoplates exhibit a thickness in the range of 5-220 nm with a relatively smooth surface. X-ray diffraction studies reveal highly crystalline CdI in hexagonal phase, which is also confirmed by the characteristic Raman A mode at 110 cm . High-resolution transmission electron microscopy and selected area electron diffraction reveal that the resulting CdI nanoplates are single crystals. Taking a step further, we show the CdI nanoplates were readily grown on other 2DLMs (e.g., WS , WSe , MoS ), forming diverse van der Waals heterostructures. Using prepatterned WS monolayer square arrays as the nucleation and growth templates, we also show that regular arrays of CdI /WS vertical heterostructures can be prepared. The synthesis of the CdI nanoplates, heterostructures, and heterostructure arrays offers a valuable material system for 2D materials science and technology.