Abstract

The success in graphene with fascinating and technologically useful properties[1] has stimulated the study of two-dimensional (2D) atomic-layer materials other than graphene, such as single layers of transition metal dichalcogenides (TMDCs, e.g., MoS₂, WS₂, WSe₂, etc)[2] and a few quintuple layers of topological insulators (TIs, e.g., Bi₂Se₃, Bi₂Te₃, Sb₂Te₃ etc)[3] . The rapid pace of progress in graphene, TMDCs and TIs and some demonstrated applications have led to the exploration of new type of electric and optoelectronic devices constructed by vertically stacking different layered materials. [4-9]

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