Comparison of physical and chemical vapor deposition for magnesium intercalation underneath epitaxial graphene.

• Magnesium physical and chemical vapor sources can intercalate epitaxial graphene. • Chemical vapor deposition reduces graphene surface metal contamination. • Physical vapor deposition allows greater intercalated metal quantities. • Magnesium is an air stable n-type dopant of epitaxial graphene. Intercalation of Mg into epitaxial graphene was investigated using chemical vapor deposition (CVD) and physical vapor deposition (PVD) for the formation of n-type doped graphene. Scanning electron microscopy and atomic force microscopy indicate PVD has significantly greater metal deposition and surface roughness compared to the CVD process. Findings from x-ray photoelectron spectroscopy infer the formation of Mg intercalated quasi-freestanding epitaxial graphene indicated by shifting of the SiC peak in C 1s spectra. This is substantiated by visual evidence from scanning tunneling electron microscopy of one or more layers of Mg residing underneath EG. Furthermore, an invariant 2D peak position in Raman spectra taken over a 7-day period in ambient conditions support arguments of the stability of electron doped Mg-intercalated epitaxial graphene. CVD offers a cleaner and smoother surface compared to PVD due to improved control over when the substrate is subjected to Mg exposure, but PVD allows for greater Mg concentrations per minute that may increase the amount of intercalated metal. [ABSTRACT FROM AUTHOR]