Tunable Ohmic, p-Type Quasi-Ohmic, and n-Type Schottky Contacts of Monolayer SnSe with Metals

Monolayer (ML) SnSe, a p-type IV–VI semiconductor, has drawn tremendous attention because of its chemical stability, high electrostatic gating efficiency, and carrier mobility, and it has been synthesized in different ways. We have comprehensively investigated the properties of the interfaces between ML SnSe and some regular metals by using first-principles calculations. Metallization of ML SnSe appears in ML SnSe–Ag, −Al, −Au, −Cu, and −Cr systems. Lateral n-type Schottky contacts with electron Schottky barrier heights of 0.42 and 0.32 eV are formed, respectively, when ML SnSe contacts with metals Ag and Al. Also, a lateral p-type quasi-ohmic contact with a hole Schottky barrier height of 0.02 eV is formed when ML SnSe contacts with metal Au. Surprisingly, ohmic contacts are formed when ML SnSe contacts with metals Cr and Cu. Our research not only has a deep understanding of the characteristics of the interfaces between ML SnSe and the metals but also offers a reference in the electrode selection for ML SnSe devices.