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High‐Performance Monolayer MoS 2 Field‐Effect Transistors on Cyclic Olefin Copolymer‐Passivated SiO 2 Gate Dielectric
Ist Teil von
Advanced optical materials, 2023-01, Vol.11 (2)
Erscheinungsjahr
2023
Link zum Volltext
Quelle
Alma/SFX Local Collection
Beschreibungen/Notizen
Abstract
Trap states of the semiconductor/gate dielectric interface give rise to a pronounced subthreshold behavior in field‐effect transistors (FETs) diminishing and masking intrinsic properties of 2D materials. To reduce the well‐known detrimental effect of SiO
2
surface traps, this work spin‐coated an ultrathin (≈5 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 × 10
11
cm
−2
eV
−1
, which enables low‐voltage 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 × 10
7
A W
−1
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.