Abstrakt
In recent years, graphene growth optimization has been one of the key routes towards large-scale, high-quality graphene production. We measure in situ residual gas content during epitaxial-graphene growth on silicon carbide (SiC) to find detrimental factors of epitaxial-graphene growth.
The growth conditions in high vacuum, in argon, purified argon, and the flow of argon are compared. The grown epitaxial graphene is studied by Raman-scattering mapping.
We determine mechanical strain, number of graphene layers and the graphene quality. The surface topography is measured by atomic force microscopy.
Charge density and carrier mobility are studied by Hall-effect measurements in van der Pauw configuration. We identify the major role of the chemical reaction of carbon and residual water.
The rate of the reaction is lowered when purified argon is used. We also show that, according to time-varying gas content, it is preferable to grow graphene at higher temperatures and shorter times.
Other sources of growth environment contamination are also discussed. The reaction of residual gas and SiC is discussed as one of the factors decreasing the lateral size of SiC atomically flat terraces and leading to their irregular shape.
The importance of purified argon and its sufficient flow rate is concluded to be important for high-quality graphene growth as it reduces the rate of undesired chemical reactions and provides a more stable and defined growth ambient.