title: MoS₂ P-type transistors and diodes enabled by high work function MoOx contacts.
abstract: The development of low-resistance source/drain contacts to transition-metal dichalcogenides (TMDCs) is crucial for the realization of high-performance logic components. In particular, efficient hole contacts are required for the fabrication of p-type transistors with MoS2, a model TMDC. Previous studies have shown that the Fermi level of elemental metals is pinned close to the conduction band of MoS2, thus resulting in large Schottky barrier heights for holes with limited hole injection from the contacts. Here, we show that substoichiometric molybdenum trioxide (MoOx, x < 3), a high work function material, acts as an efficient hole injection layer to MoS2 and WSe2. In particular, we demonstrate MoS2 p-type field-effect transistors and diodes by using MoOx contacts. We also show drastic on-current improvement for p-type WSe2 FETs with MoOx contacts over devices made with Pd contacts, which is the prototypical metal used for hole injection. The work presents an important advance in contact engineering of TMDCs and will enable future exploration of their performance limits and intrinsic transport properties.
authors.affiliation: Electrical Engineering and Computer Sciences and §Berkeley Sensor and Actuator Center, University of California , Berkeley, California 94720, United States.
authors.forename: Steven
authors.initials: S
authors.lastname: Chuang
authors.forename: Corsin
authors.initials: C
authors.lastname: Battaglia
authors.forename: Angelica
authors.initials: A
authors.lastname: Azcatl
authors.forename: Stephen
authors.initials: S
authors.lastname: McDonnell
authors.forename: Jeong Seuk
authors.initials: JS
authors.lastname: Kang
authors.forename: Xingtian
authors.initials: X
authors.lastname: Yin
authors.forename: Mahmut
authors.initials: M
authors.lastname: Tosun
authors.forename: Rehan
authors.initials: R
authors.lastname: Kapadia
authors.forename: Hui
authors.initials: H
authors.lastname: Fang
authors.forename: Robert M
authors.initials: RM
authors.lastname: Wallace
authors.forename: Ali
authors.initials: A
authors.lastname: Javey
mesh_terms: D004220:Disulfides; D017097:Electric Impedance; D008982:Molybdenum; D010087:Oxides; D014173:Transistors, Electronic
chemical_list: D004220:Disulfides; D010087:Oxides; C539565:molybdenum dioxide; D008982:Molybdenum; C082964:molybdenum disulfide