Ultraclean graphene sample fabrication
For a long time after the discovery of graphene, the measured electrical properties of real graphene samples were far below the theoretically expected values. The main causeof this problem was the contamination accumulated on the surface of the graphene flakes which act as scatterers during electron propagation. Thus, making and maintaining clean graphene surfaces has become a key factor in a successful experiment in the domain of graphene research.
To get rid of the surface contamination a novel fabrication technique has been proposed a few years ago and since then used widely in practice: graphene sheets encapsulated in hexa-Boron-Nitride crystals. The subject of the first part of the talk is a brief description of the technique and the observed quality of the produced samples. In the second part we concentrate on the contact methods used in these cases: side contacts and point contacts in the middle of the flake. A brand new method for the realisation of the latter will be shown and also some results will be presented.