1 research outputs found
HighâPerformance Monolayer MoS 2 FieldâEffect Transistors on Cyclic Olefin CopolymerâPassivated SiO 2 Gate Dielectric
Abstract Trap states of the semiconductor/gate dielectric interface give rise to a pronounced subthreshold behavior in fieldâeffect transistors (FETs) diminishing and masking intrinsic properties of 2D materials. To reduce the wellâknown detrimental effect of SiO 2 surface traps, this work spinâcoated an ultrathin (â5 nm) cyclic olefin copolymer (COC) layer onto the oxide and this hydrophobic layer acts as a surface passivator. The chemical resistance of COC allows to fabricate monolayer MoS 2 FETs on SiO 2 by standard cleanroom processes. This way, the interface trap density is lowered and stabilized almost fivefold, to around 5 Ă 10 11 cm â2 eV â1 , which enables lowâvoltage FETs even on 300 nm thick SiO 2 . In addition to this superior electrical performance, the photoresponsivity of the MoS 2 devices on passivated oxide is also enhanced by four orders of magnitude compared to nonpassivated MoS 2 FETs. Under these conditions, negative photoconductivity and a photoresponsivity of 3 Ă 10 7 A W â1 is observed which is a new highest value for MoS 2 . These findings indicate that the ultrathin COC passivation of the gate dielectric enables to probe exciting properties of the atomically thin 2D semiconductor, rather than interface trap dominated effects.Highâperformance monolayer MoS 2 âbased electronic and optoelectronic devices are fabricated on SiO 2 gate dielectric passivated with cyclic olefin copolymer. The passivation eliminates the interaction with interface trap states which are detrimental for the electronic and optoelectronic performance of the devices. imag