Highly efficient and stable MoS2 FETs with reversible n-doping using a dehydrated poly(vinyl-alcohol) coatingElectronic supplementary information (ESI) available: Electrical characterization of a PVA film, current behaviour of PVA-doped MoS2 FETs under humid conditions, photoluminescence of MoS2 before and after doping, spectroscopy characterization of PVA films and analysis of the MoS2 film thickness, environment and passivation effects on the device. See DOI: 10.1039/c6nr06980k

• Main Authors: Lockhart de la Rosa, César J, Nourbakhsh, Amirhasan, Heyne, Markus, Asselberghs, Inge, Huyghebaert, Cedric, Radu, Iuliana, Heyns, Marc, De Gendt, Stefan
• Format: Journal Article
• Language: English
• Published: 22.12.2016
• ISSN: 2040-3364; 2040-3372
• DOI: 10.1039/c6nr06980k

Despite rapid progress in 2D molybdenum disulfide (MoS 2 ) research in recent years, MoS 2 field-effect transistors (FETs) still suffer from a high metal-to-MoS 2 contact resistance and low intrinsic mobility, which are major hindrances to their future application. We report an efficient technique to dope thin-film MoS 2 FETs using a poly(vinyl-alcohol) (PVA) polymeric coating. This results in a reduction of the contact resistance by up to 30% as well as a reduction in the channel resistance to 20 kΩ sq −1 . Using a dehydration process, we were able to effectively control the surface interactions between MoS 2 and the more electropositive hydroxyl groups (-OH) of PVA, which provided a controllable and yet reversible increase in the charge carrier density to a value of 8.0 × 10 12 cm −2 . The non-covalent, thus non-destructive, PVA doping of MoS 2 increases the carrier concentration without degrading the mobility, which shows a monotonic increase while enhancing the doping effect. The PVA doping technique is then exploited to create heavily doped access regions to the intrinsic MoS 2 channel, which yields 200% increase of the ON-state source-drain current. This establishes PVA doping as an effective approach to enhance the transport properties of MoS 2 FETs for a variety of applications. Despite rapid progress MoS 2 field-effect transistors (FET's) still suffers major hindrances like high contact resistance ( R C ). Here we enhanced the performance of FET's by functionalization with an organic polymer.