Abstract
AbstractWe have used low-energy electron diffraction and microscopy to compare the growth of graphene on hydrogen-free Ge(111) and Ge(110) from an atomic carbon flux. Growth on Ge(110) leads to significantly better rotational alignment of graphene domains with the substrate. To explain the poor rotational alignment on Ge(111), we have investigated experimentally and theoretically how the adatom reconstructions of Ge interact with graphene. We find that the ordering transition of the Ge(111) adatom reconstruction is not significantly perturbed by graphene. Density functional theory calculations show that graphene on reconstructed Ge(110) has large-amplitude corrugations, whereas it is remarkably flat on reconstructed Ge(111). We argue that the absence of corrugations prevents graphene islands from locking into a preferred orientation.
Highlights
Because of its intrinsic two-dimensional (2D) character, graphene interacts weakly with the substrates on which it is grown
Graphene growth on Ge(110) by chemical vapor deposition (CVD) has been shown to exhibit considerably improved rotational alignment compared with growth on Ge(111).[7]
Because our growth by physical vapor deposition (PVD) occurs in the absence of hydrogen, our results show that hydrogen is not responsible for the preferred graphene domain alignment on the (110) surface
Summary
Because of its intrinsic two-dimensional (2D) character, graphene interacts weakly with the substrates on which it is grown. Graphene domains tend to nucleate in random orientations, producing polycrystalline films.[1,2,3,4,5] Much has been learned about the factors that control domain orientation, on metal substrates. Graphene growth on Ge(110) by chemical vapor deposition (CVD) has been shown to exhibit considerably improved rotational alignment compared with growth on Ge(111).[7] Here, we clarify the reasons for this improvement
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