Pervasive Ohmic Contacts in Bilayer Bi2O2Se–Metal Interfaces

Due to their outstanding gate electrostatics, two-dimensional (2D) semiconducting materials are regarded as promising channel materials used in the next-generation field-effect transistors (FETs). However, a Schottky barrier often existing at the 2D semiconductor–metal interface can evidently degrade the device performance. Very lately, 2D layered semiconducting bismuth oxyselenide (Bi2O2Se) is synthesized and exhibits high carrier mobility and excellent air stability. We conduct a systematic exploration, for the first time, on the interfacial nature of bilayer (BL) Bi2O2Se in contact with six metals (Sc, Ti, Ag, Au, Pd, and Pt) that cover a wide work function range by density functional theory-based band structure calculations and quantum transport simulations in a FET configuration. Remarkably, our results reveal that all the contacts in the lateral direction are n-type Ohmic due to the robust beyond-gap Fermi level pinning at the interface. Experimentally, the actual BL Bi2O2Se FET with a Au/Pd electro...