One-Pot Selective Epitaxial Growth of Large WS₂/MoS₂ Lateral and Vertical Heterostructures

Abstract

Controllable nucleation sites play a key role in the selective growth of heterostructures. Here, we are the first to report a one-pot strategy to realize the confined and selective growth of large MoS2/WS2 lateral and vertical heterostructures. A hydroxide-assisted process is introduced to control the nucleation sites, thereby realizing the optional formation of lateral and vertical heterostructures. Time-of-flight secondary ion mass spectrometry verifies the critical role of hydroxide groups toward the controllable growth of these heterostructures. The size of the as-grown MoS2/WS2 lateral heterostructures can be as large as 1 mm, which is the largest lateral size reported thus far. The obtained MoS2/WS2 heterostructures have a high carrier mobility of ∼58 cm2 V–1 s–1, and the maximum on/off current ratio is >108. This approach provides not only a pathway for the selective growth of large MoS2/WS2 lateral and vertical heterostructures but also a fundamental understanding of surface chemistry for controlling the selective growth of transition-metal dichalcogenide heterostructures.

Single-step chemical vapour deposition of anti-pyramid MoS2/WS2 vertical heterostructures

“…According to ref. 33 35 Based on the results of different theoretical calculations, [36][37][38] it is seen that the most stable stacking of 2-layer TMDs is AA′ stacking, which is the same in our heterostructures as demonstrated. In this structure, the top layer WS 2 stacks on the bottom layer MoS 2 with an orientation of difference 60°, which makes the Klein edges of WS 2 have the same epitaxial direction as that of the zig-zag edges of MoS 2 .…”

High-Performance Photodetectors Based on Lateral Monolayer MoS2/WS2 Heterojunctions

“…Besides, Wang's group [25] has certified suppressed electron-hole (e-h) recombination in lateral heterostructures. As previously reported, the lateral heterostructures showed higher carrier mobility [26] whereas the vertical heterostructures usually increased the photoactive area [23] and/or enhanced current drive per area [27]. Moreover, the in-plane interfaces of lateral heterostructures showed stronger emission intensity than both sides [14].…”

“…The suggesting monolayer one [26,34,35]. When considering WS2, the peak intensity ratio of longitudinal acoustic mode (2LA) [36] at 352 cm -1 to A1g mode, i.e.…”

The Photodetectors Based on Lateral Monolayer MoS2/WS2 Heterojunctions

“…Besides, Wang’s group [ 29 ] has certified suppressed electron–hole (e–h) recombination in lateral heterostructures. As previously reported, the lateral heterostructures showed higher carrier mobility [ 30 ] whereas the vertical heterostructures usually increased the photoactive area [ 27 ] and/or enhanced current drive per area [ 31 ]. Moreover, the in-plane interfaces of lateral heterostructures showed stronger emission intensity than both sides [ 14 ].…”

“…Finally, the carrier gas was changed from Ar to Ar/H 2 (5% H 2 ), and the heating center heated to 780 °C within 10 min and kept for 10 min to allow WS 2 to grow along the edges of MoS 2 –OH bilayers, forming MoS 2 /WS 2 lateral heterostructures. The more details of the heterostructure synthesis refer to previous work [ 30 ].…”