Researchers from the Georgia Institute of Technology developed a new method to grow high quality layers of epitaxial graphene on silicon carbide wafers. They call this method confinement controlled sublimation, and it relies on controlling the vapor pressure of gas-phase silicon in the high-temperature furnace used for fabricating the material.
Basically, growing graphene on silicon carbide requires heating the material to about 1,500 degrees Celsius under high vacuum. But uncontrolled evaporation lead to poor quality material. Controlling the temperature is essential for high-quality graphene. The new developed method begins by placing a silicon carbide wafer into an enclosure made of graphite. A small hole in the container controls the escape of silicon atoms as the one-square-centimeter wafer is heated, maintaining the rate of silicon evaporation and condensation near its thermal equilibrium. The growth of epitaxial graphene can be done in a vacuum or in the presence of an inert gas such as argon, and can be used to produce both single layers and multiple layers of the material.