Van der Waals Contact to 2D Semiconductors with a Switchable Electric Dipole: Achieving Both n‐ and p‐Type Ohmic Contacts to Metals with a Wide Range of Work Functions

Abstract Two‐dimensional (2D) layered semiconductors with an intrinsic electric dipole p (pS for short), including group III 2 ‐VI 3 ferroelectrics and various Janus semiconductors, are attracting increasing attention for their exotic properties and versatile applications. Their potential in metal–semiconductor junctions is revealed. It is demonstrated that, for pS contacting to 2D metals with a wide range of work‐functions, Schottky‐barrier‐free (SB‐free) and tunable n‐ to p‐type contacts can be obtained, which is important for complementary metal‐oxide‐semiconductor logical circuitry. As expected, low (high) work‐function (WF) metals form n‐type (p‐type) SB‐free contacts to pS. What is unexpected is the behavior of medium‐WF metal‐pS junctions (MpSJ); that is, by switching the polarization in pS, both n‐ and p‐type SB‐free contacts can be obtained by the same pS contacting to metals with a wide range of WF. More importantly, MpSJ with bilayer pS can form both n‐ and p‐type SB‐free contacts. These findings, SB‐free and contact‐type‐tunable of MpSJ for metals with a wide range of work‐functions, demonstrate the great potential of 2D pS for device applications.