Secondary granulation-assisted CVD growth of WS2, TiS2 and NbS2 crystals

Abstract

Chemical vapor deposition (CVD) is a cost-effective and scalable approach to prepare high-quality two-dimensional (2D) transition metal dichalcogenides (TMDCs), which is crucial for practical applications. Nevertheless, how to sublimate metal precursors with high melting point efficiently is still challenging. Herein, we demonstrate a novel secondary granulation-assisted route to adjust the supply of WO3 at moderate temperature (730 [Formula: see text]C), guarantee the appropriate tungsten/chalcogen ratio, and then achieve the controllable growth of monolayer WS2 crystals. Transmission electron microscopy, Raman and other characterizations indicate their high crystallinity. Notably, the domain size, nucleation density and morphology can be regulated by the size of the granulated WO3 particles. Moreover, the related mechanism is explained in detail, which applies equally to the steerable growth of TiS2 and NbS2, confirming the versatility of this method for growing 2D TMDCs. Therefore, this work offers a facile route for the microthermal CVD growth of 2D TMDCs crystals and drives the development of applications.