Fermi‐Level Pinning‐Free WSe<sub>2</sub> Transistors via 2D Van der Waals Metal Contacts and Their Circuits
Jisu Jang, Hyun‐Soo Ra, Jongtae Ahn, Tae Wook Kim, Seung Ho Song, Soohyung Park, Takashi Taniguch, Kenji Watanabe, Kimoon Lee, Do Kyung Hwang
Abstract
Abstract Precise control over the polarity of transistors is a key necessity for the construction of complementary metal–oxide–semiconductor circuits. However, the polarity control of 2D transistors remains a challenge because of the lack of a high‐work‐function electrode that completely eliminates Fermi‐level pinning at metal–semiconductor interfaces. Here, a creation of clean van der Waals contacts is demonstrated, wherein a metallic 2D material, chlorine‐doped SnSe 2 (Cl–SnSe 2 ), is used as the high‐work‐function contact, providing an interface that is free of defects and Fermi‐level pinning. Such clean contacts made from Cl–SnSe 2 can pose nearly ideal Schottky barrier heights, following the Schottky–Mott limit and thus permitting polarity‐controllable transistors. With the integration of Cl–SnSe 2 as contacts, WSe 2 transistors exhibit pronounced p‐type characteristics, which are distinctly different from those of the devices with evaporated metal contacts, where n‐type transport is observed. Finally, this ability to control the polarity enables the fabrication of functional logic gates and circuits, including inverter, NAND, and NOR.