Abstract
One of the exciting features of graphene is a possibility to affect its electrical, optical, and chemical properties by gating, that is, by application of an electric field. This requires reasonably large fields (at the level of 1 V/nm necessary to induce relevant electron density changes) applied over a gating dielectric material. At these fields, most dielectrics show some conduction, which leads to an important question: what is the best dielectric to gate graphene? Here, we show that this question is imprecise as a dielectric material produced by different fabrication methods can exhibit dramatically different gating properties. Namely, we show that two oxide dielectrics (hafnia and alumina) result in positive hysteresis of graphene gating characteristics being fabricated by atomic layer deposition and negative hysteresis being fabricated by electron beam evaporation. We attribute this behavior to the stoichiometry of the samples and oxygen ion migration. It implies that oxide dielectrics should be avoided in graphene gated devices working at room temperatures.
Highlights
IntroductionIt turned out that graphene possesses massless Dirac electrons[2] with extremely high mobility, strongly interacts with light,[3] and demonstrates a whole set of unusual properties important for applications.[4] One of the most interesting features of graphene is a possibility to strongly affect its electrical,[2] optical,[5] plasmonic,[6,7] and chemical[8] properties by electrical gating, that is, by an application of an electric field
Isolation of graphene[1] created an air of excitement in science and technology
We show that oxide dielectrics fabricated by atomic layer deposition (ALD) exhibit positive hysteresis of graphene gating characteristics while the same dielectrics fabricated by electron beam (e-beam) evaporation demonstrate negative hysteresis
Summary
It turned out that graphene possesses massless Dirac electrons[2] with extremely high mobility, strongly interacts with light,[3] and demonstrates a whole set of unusual properties important for applications.[4] One of the most interesting features of graphene is a possibility to strongly affect its electrical,[2] optical,[5] plasmonic,[6,7] and chemical[8] properties by electrical gating, that is, by an application of an electric field. One still needs to apply reasonably large fields (at the level of 1 V/nm) over a gating dielectric material in order to significantly change the graphene properties. At these fields, most dielectrics show some conduction,[9] which leads to an important question: what is the best dielectric to gate graphene? Most dielectrics show some conduction,[9] which leads to an important question: what is the best dielectric to gate graphene? This question is especially important for graphene field effect devices,[10,11] graphene-based optical modulators,[12] and photodetectors.[13]
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