Coexistence of Ohmic Contact and Fermi Level Pinning at 2D Electride/2D Semiconductor Interfaces

It is well known that Fermi level pinning (FLP) always leads to hardly tunable Schottky barriers, thereby hindering the formation of an Ohmic contact (OhC). As a result, FLP and OhC are often implicitly regarded as being mutually exclusive. Herein, we demonstrate a rare case of two-dimensional (2D) electride/2D semiconductor interfaces, where OhC and FLP coexist. Owing to the large work function differences and the presence of 2D electron gas, n-type (p-type) OhC can be formed as the Fermi level is pinned within the conduction (valence) band. In n-type OhC, FLP results from significant interface dipoles, whereas in p-type OhC, the Fermi level is pinned by localized electronic states in the van der Waals gap, which is fundamentally distinct from conventional metal-induced or disorder-induced gap states. This work not only presents robust OhC under strong FLP but also enriches the fundamental understanding of FLP mechanisms.