Modular van der Waals MOSFETs through layer-by-layer chalcogen substitutions.

Layer-by-layer chalcogen substitution in TMDCs enables modular van der Waals heterostructures with integrated electronic phases, including ultrascaled MOSFETs with subthreshold swing at subnanometer oxide thickness.

• Why it matters: Tuning electronic phases in TMDCs is crucial for advancing 2D electronic devices, but current methods lack spatial precision and integration of diverse phases within a single heterostructure.
• What they did: The authors used vapor-phase layer-by-layer chalcogen substitution to convert p-type WSe2 multilayers into insulating WOx, n-type WS2, and semimetallic WTe2, creating spatially precise heterostructures with distinct electronic phases.
• The result: This approach enabled the integration of these phases into modular heterostructures, demonstrated by ultrascaled MOSFETs with an unprecedented subthreshold swing at subnanometer oxide thickness, opening new avenues for 2D electronics.