Gate‐Tunable Graphene–WSe2 Heterojunctions at the Schottky–Mott Limit

• Published in: Advanced materials (Weinheim) Vol. 31; no. 24; pp. e1901392 - n/a
• Main Authors: LaGasse, Samuel W., Dhakras, Prathamesh, Watanabe, Kenji, Taniguchi, Takashi, Lee, Ji Ung
• Format: Journal Article
• Language: English
• Published: Weinheim Wiley Subscription Services, Inc 01.06.2019
• Subjects: 2D materials; Electrical junctions; Fermi level pinning; Graphene; Heterojunctions; Materials science; Pinning; Schottky junctions; Schottky–Mott limit; van der Waals heterostructures
• ISSN: 0935-9648; 1521-4095
• DOI: 10.1002/adma.201901392

Metal–semiconductor interfaces, known as Schottky junctions, have long been hindered by defects and impurities. Such imperfections dominate the electrical characteristics of the junction by pinning the metal Fermi energy. Here, a graphene–WSe2 p‐type Schottky junction, which exhibits a lack of Fermi level pinning, is studied. The Schottky junction displays near‐ideal diode characteristics with large gate tunability and small leakage currents. Using a gate electrostatically coupled to the WSe2 channel to tune the Schottky barrier height, the Schottky–Mott limit is probed in a single device. As a special manifestation of the tunable Schottky barrier, a diode with a dynamically controlled ideality factor is demonstrated. The Schottky–Mott limit is studied in a dual‐gated graphene–WSe2 heterojunction. Nearly ideal Schottky diode characteristics with extremely large gate tunability are demonstrated. The graphene–WSe2 Schottky barrier height at each gate voltage is determined, showing one‐to‐one modulation, following the Schottky–Mott rule. These results have broad implications in contact engineering for 2D materials and optoelectronic devices.