Hypotaxy‐Enabled Selective Growth of MoS ₂ for Laterally‐Connected Edge and van der Waals Bottom Contacts

ABSTRACT Device fabrication of 2D semiconductors typically involve sequential synthesis and electrode patterning, which inevitably cause damage and contamination in 2D channels, hindering the ideal metal‐semiconductor interfaces. Here we report a process‐efficient and defect‐minimizing strategy based on hypotaxy, the downward growth of transition metal dichalcogenides (TMDs) beneath nanoporous graphene with crystalline alignment by chalcogenizing the graphene‐covered metal films, which eliminates the need for channel etching and enables direct formation of either laterally connected edge contacts or van der Waals (vdW)‐gapped bottom contacts. The molybdenum (Mo) film can be selectively transformed only in designated regions, into a lateral Mo‐MoS 2 junction or a vertical MoS 2 /Mo structure by tuning the graphene thickness or by locally varying the Mo thicknesses, respectively. In one implementation, MoS 2 forms only beneath monolayer graphene, whereas the Mo under multilayer graphene remains unreacted, producing a laterally connected Mo‐MoS 2 edge contact. Second, the thinner Mo film in the channel region is fully converted into MoS 2 within a set growth time, while only the top region transforms in thicker Mo film, leading to a vertical vdW MoS 2 /Mo interface. This bottom‐up integration minimizes lithography‐induced contamination and enables wafer‐scale fabrication of MoS 2 transistor arrays (200 devices) with reduced contact resistance and highly device‐to‐device uniformity.