Mobility enhancement and highly efficient gating of monolayer MoS_ 2 transistors with polymer electrolyte

摘要

We report electrical characterization of monolayer molybdenum disulfide (MoS_ 2) devices using a thin layer of polymer electrolyte (PE) consisting of poly(ethylene oxide) (PEO) and lithium perchlorate (LiClO_ 4) as both a contact-barrier reducer and channel mobility booster. We find that bare MoS_ 2 devices (without PE) fabricated on Si/SiO_ 2 have low channel mobility and large contact resistance, both of which severely limit the field-effect mobility of the devices. A thin layer of PEO/LiClO_ 4 deposited on top of the devices not only substantially reduces the contact resistance but also boost the channel mobility, leading up to three-orders-of-magnitude enhancement of the field-effect mobility of the device. When the PE is used as a gate medium, the MoS_ 2 field-effect transistors exhibit excellent device characteristics such as a near ideal subthreshold swing and an on/off ratio of 10~ 6 as a result of the strong gate-channel coupling.