Molecular doping of MoS2 transistors by self-assembled oleylamine networks

Thin MoS2 films continue to be of key interest for numerous applications; however, effective doping and high metal to MoS2 contact resistance are challenges for future applications. We report on the self-assembly of oleylamine on top of MoS2 thin-films and the effective doping of MoS2 thin-film field effect transistors by oleylamine. Atomic force microscopy revealed that oleylamine organizes in lamellae domains on MoS2 thin films with similar characteristics of those previously observed on highly ordered pyrolytic graphite. A carrier concentration increase from 7.1 × 1011 cm−2 up to 1.9 × 1013 cm−2 at 0 V gate voltage is achieved together with a reduction of the contact resistance by a factor of 5 when using gold as metal contact. Furthermore, this non-covalent doping proves to be removable and reproducible among different flakes and does not degrade the electron mobility. Thus, this work opens the path for future works on controlling the doping of MoS2 by proper selection of the self-assembled species.