Position-Selective Growth of 2D WS2-Based Vertical Heterostructures via a One-Step CVD Approach

Vertical heterostructures of two-dimensional (2D) transition metal dichalcogenides (TMDCs) provide a prospective foreground for practical applications via combining novel physical characteristics that are distinguished from those of traditional counterparts. Here, we report the position-selective growth of 2D WS2-based vertical heterostructures, including WS2/MoS2, WS2/MoS2-Mo0.42W0.58S2, WS2/MoS2-Mo1-xWxS2 (0.4 <= x <= 0.85), and WS2/Mo1-xWxS2 (0 <= x <= 0.76), with the WS2 monolayer as the top layer by a one-step chemical vapor deposition (CVD) method. Systematical Raman and photoluminescence (PL) characterizations corroborate that position-dependent vertical heterostructures exhibit a significant relationship between structural/optical characteristics and compositions. A possible growth mechanism of various 2D WS2-based heterostructures at different deposition regions is discussed based on the variation of metallic atoms along the gas flow direction. The current work supplies a promising and efficient strategy to fabricate complex heterostructures composed of various TMDCs, which is a crucial step to develop functional optoelectronic applications.