Wafer-scale and deterministic patterned growth of monolayer MoS2via vapor–liquid–solid method

Abstract

Vapor transportation is the core process in growing transition-metal dichalcogenides (TMDCs) by chemical vapor deposition (CVD). One inevitable problem is the spatial inhomogeneity of vapors. The non-stoichiometric supply of transition-metal precursors and chalcogens leads to poor control in the products’ location, morphology, crystallinity, uniformity and batch to batch reproducibility. The vapor–liquid–solid (VLS) growth method often involves molten precursors (e.g., non-volatile Na₂MoO₄) at growth temperatures higher than their melting points. The liquid Na₂MoO₄ can precipitate out solid MoS₂ monolayers when saturated with sulfur vapor. Taking advantage of the VLS growth, we attained three kinds of important achievements: (i) a 4-inch-wafer-scale uniform growth of MoS₂ flakes on SiO₂/Si substrates, (ii) a 2-inch-wafer-scale growth of continuous MoS₂ film with the grain size exceeding 100 μm on sapphire substrates, and (iii) a patterned (site-controlled) growth of MoS₂ flakes and films. We clarified that the VLS growth thus paves a new way for the high-efficient and scalable synthesis of two-dimensional TMDC monolayers.