Graphene‐Enhanced Metal Transfer Printing for Strong van der Waals Contacts between 3D Metals and 2D Semiconductors.

2D semiconductors have shown great potentials for ultra‐short channel field‐effect transistors (FETs) in next‐generation electronics. However, because of intractable surface states and interface barriers, it is challenging to realize high‐quality contacts with low contact resistances for both p‐ and n‐ 2D FETs. Here, a graphene‐enhanced van der Waals (vdWs) integration approach is demonstrated, which is a multi‐scale (nanometer to centimeter scale) and reliable (≈100% yield) metal transfer strategy applicable to various metals and 2D semiconductors. Scanning transmission electron microscopy imaging shows that 2D/2D/3D semiconductor/graphene/metal interfaces are atomically flat, ultraclean, and defect‐free. First principles calculations indicate that the sandwiched graphene monolayer can eliminate gap states induced by 3D metals in 2D semiconductors. Through this approach, Schottky barrier‐free contacts are realized on both p‐ and n‐type 2D FETs, achieving p‐type MoTe2, p‐type black phosphorus and n‐type MoS2 FETs with on‐state current densities of 404, 1520, and 761 µA µm−1, respectively, which are among the highest values reported in literature. [ABSTRACT FROM AUTHOR]