July 15, 2015

Graphene Week 2015 looks at the electronic properties of 2d materials

(July 15, 2015)  Graphene Week 2015 was buzzing with activity throughout the University of Manchester venue, with more than 600 delegates presenting and discussing their work, networking and making plans for the future. Each morning of the conference was given over to plenary sessions, with keynote presentations from invited speakers. Here we report on the Tuesday plenary, which was devoted to the electronic properties of graphene and related layered materials.

Electronic transport in the ultraclean limit

James Hone of Columbia University in New York began with a discussion of electronic transport in 2d materials in the ultraclean limit.

With electronics applications, graphene is generally laid on a substrate made of a bulk material. The problem is that, owing to the presence of dangling chemical bonds, 3d materials tend to be poor substrates for 2d materials such as graphene. One solution is to use hexagonal boron nitride (hBN), which is both an insulator and 2d material, and so does not have the problematic bonds.

How to create such hBN-graphene heterostructures? Graphene may be transferred onto boron nitride films with the aid of polymers. That is, graphene flakes are exfoliated onto polymers, aligned with a mask, and the flakes stacked on top of each other. Such a heterostructure displays enhanced charge carrier mobility, a lower degree of disorder, and improved field-effect transistor performance.

Looking beyond graphene, few 2d materials have so far been studied, and we have a long way to go before they are fully understood. One 2d material of interest is molybdenum disulphide, with the heterostructure formed with silicon dioxide.

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