BilayerLateral Heterostructures of Transition-MetalDichalcogenides and Their Optoelectronic Response

Two-dimensional lateral heterojunctions based on monolayer transition metal dichalcogenides (TMDs) have received increasing attention given that their direct band gap makes them very attractive for optoelectronic applications. Although bilayer TMDs present an indirect band gap, their electrical properties are expected to be less susceptible to ambient conditions, with higher mobilities and density of states when compared to monolayers. Bilayers and few-layers single domain devices have already demonstrated higher performance in radio frequency and photo-sensing applications. Despite these advantages, lateral heterostructures based on bilayer domains have been less explored. Here, we report the controlled synthesis of multi-junction bilayer lateral heterostructures based on MoS2-WS2 and MoSe2-WSe2 mono-domains. The hetero-junctions are created via sequential lateral edge-epitaxy that happens simultaneously in both the first and the second layer. A phenomenological mechanism is proposed to explain the growt...