Engineering Chemically Active Defects in Monolayer MoS2 Transistors via Ion‐Beam Irradiation and Their Healing via Vapor Deposition of Alkanethiols

• Published in: Advanced materials (Weinheim) 2017-05, Vol.29 (18), p.n/a
• Main Authors: Bertolazzi, Simone, Bonacchi, Sara, Nan, Guangjun, Pershin, Anton, Beljonne, David, Samorì, Paolo
• Format: Article
• Language: English
• Subjects: Alkanes; Argon; Argon ions; Defects; Electrical properties; Exposure; Field effect transistors; Fluence; Healing; Ion beams; Ion bombardment; ion‐beam irradiation; Irradiation; Materials science; Metal sheets; Molybdenum disulfide; monolayer MoS2; Optoelectronic devices; Semiconductor devices; Sulfur; sulfur vacancies; thiol chemistry; Transistors; Vacancies; Vapor deposition
• ISSN: 0935-9648; 1521-4095
• DOI: 10.1002/adma.201606760

Irradiation of 2D sheets of transition metal dichalcogenides with ion beams has emerged as an effective approach to engineer chemically active defects in 2D materials. In this context, argon‐ion bombardment has been utilized to introduce sulfur vacancies in monolayer molybdenum disulfide (MoS2). However, a detailed understanding of the effects of generated defects on the functional properties of 2D MoS2 is still lacking. In this work, the correlation between critical electronic device parameters and the density of sulfur vacancies is systematically investigated through the fabrication and characterization of back‐gated monolayer MoS2 field‐effect transistors (FETs) exposed to a variable fluence of low‐energy argon ions. The electrical properties of pristine and ion‐irradiated FETs can be largely improved/recovered by exposing the devices to vapors of short linear thiolated molecules. Such a solvent‐free chemical treatment—carried out strictly under inert atmosphere—rules out secondary healing effects induced by oxygen or oxygen‐containing molecules. The results provide a guideline to design monolayer MoS2 optoelectronic devices with a controlled density of sulfur vacancies, which can be further exploited to introduce ad hoc molecular functionalities by means of thiol chemistry approaches. Ion irradiation is used to controllably introduce sulfur vacancies in monolayer MoS2 sheets, which serve as channel material in field‐effect transistors. The evolution of critical device parameters is systematically investigated as a function of sulfur‐vacancy density. A vapor‐phase treatment, based on short linear thiolated molecules, enables a remarkable recovery of the functional properties of defective 2D MoS2.