Advanced transistors (FinFET and GAA)
Among 2D materials, why are transition metal dichalcogenides such as MoS2, rather than graphene, mainly studied as channels for logic transistors?
- AGraphene has no bandgap, so a gate voltage cannot shut off the current well enough
- BGraphene is only stable at a thickness of 1 cm or more
- CGraphene is an insulator that does not conduct electricity
Show answer and explanation
Answer: A. Graphene has no bandgap, so a gate voltage cannot shut off the current well enough
Graphene has very high mobility but no bandgap, so current flows even in the off state and the on/off current ratio stays small. Transition metal dichalcogenides such as MoS2 and WSe2 are semiconductors with a bandgap even as a single layer, and they work as transistors with channels about 0.65 nm thick. They are therefore studied as the next candidates for thinning channels beyond silicon nanosheets.
- A. Correct. Being unable to turn off is fatal for logic.
- B. Graphene is stable even as a single atomic layer.
- C. Graphene conducts electricity very well.
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