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Large-area graphene-on-insulator substrates and devices thereon

IP.com Disclosure Number: IPCOM000207320D
Publication Date: 2011-May-25
Document File: 4 page(s) / 44K

Publishing Venue

The IP.com Prior Art Database

Abstract

Disclosed are graphene-on-insulator substrates comprising two or more tiles of single-domain, few-or-multilayer graphene disposed on an insulating base substrate, wherein the crystal orientation of each graphene tile has the same azimuthal alignment. Also disclosed are methods of forming such graphene-on-insulator substrates.

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Large-area graphene-on-insulator substrates and devices thereon

Graphene-based nanoelectronics is expected to require large-area graphene-on-insulator substrates. Such substrates might comprise graphene on a completely insulating base substrate or graphene on an insulating layer on a base substrate containing conductive regions. Formation of large-area graphene-on-insulator substrates by graphene layer transfer has been described previously for graphene layers formed by exfoliation from graphite (in which case the large area of graphene comprises a plurality of individual, spaced-apart peels, imprints, or stampings from highly oriented pyrolytic graphite) [1] and by growth on metal layer catalysts from vapor or solid carbon sources (in which case the large area of graphene is in the form of one continuous sheet of virtually unlimited size, constrained only by the size of the metal foil on which the graphene is grown) [2]. In both of these cases, the graphene is multi-domain with a random orientation; however, given the anisotropic electrical and electronic properties of graphene, it would be desirable to have graphene-on-insulator substrates in which the azimuthal orientation of the graphene is known and controlled.

Graphene-on-insulator substrates formed by transferring single-domain graphene from a SiC growth substrate to an insulating substrate have also been described [3, 4], but only for the case of a single graphene transfer per insulating substrate, resulting in a single graphene "tile". The disclosed invention provides graphene-on-insulator substrates comprising two or more tiles of single-domain, few-or-multilayer graphene disposed on an insulating substrate, wherein the crystal orientation of each graphene tile has a preselected azimuthal alignment with respect to the axes of the base substrate.

In particular, the disclosed invention provides a graphene-on-insulator substrate comprising two or more large, single-domain, few-or-multilayer graphene layer stacks (~<2-5 layers) on an insulating carrier substrate, with the transferred graphene layer domains having the same azimuthal orientation. The invention utilizes graphene donor substrates comprising graphene layers or graphene layer stacks (~<2-5 layers) formed on single crystal SiC by Si desorption at elevated temperatures in the range 1200 - 1600 degrees C [5, 6]. The graphene donor substrates are free of the grain boundaries commonly found in graphite because the graphene is formed epitaxially on a single crystal of SiC. In principle, the lateral dimensions of the graphene layers can be as large as those of the SiC substrate (e.g. 50 mm). However, even if graphene domains grown in this way were smaller (for example few micrometers in size), they would all have the same azimuthal orientation, since they are grown epitaxially on the SiC single crystal, or donor substrate in general. The proposed transfer technique preserves this orientation relationship between the var...