Researchers boost graphene quality with silicon evaporation technique

The researchers' confinement controlled sublimation technique relies on controlling the vapour pressure of gas-phase silicon in the high temperature furnace used for fabricating the material. They believe it could soon be scaled up for electronics manufacturing. "For growing high quality graphene on silicon carbide, controlling the evaporation of silicon at just the right temperature is essential," said Walt de Heer, a professor who pioneered the technique at the Georgia Tech School of Physics. "By precisely controlling the rate at which silicon comes off the wafer, we can control the rate at which graphene is produced. That allows us to produce very nice layers of epitaxial graphene." De Heer and his team began by placing a silicon carbide wafer into an enclosure made of graphite. A small hole in the container controlled the escape of silicon atoms as the 1cm2 wafer was heated, maintaining the rate of silicon evaporation and condensation near its thermal equilibrium. According to De Heer, the growth of the epitaxial graphene could be controlled in a vacuum or in the presence of an inert gas such as argon, and could be used to produce both single layers and multiple layers of the material. "This technique seems to be completely in line with what people might one day do in fabrication facilities," De Heer noted. "We believe this is quite significant in allowing us to rationally and reproducibly grow graphene on silicon carbide. We feel we now understand the process, and believe it could be scaled up for electronics manufacturing."