  Magnesium intercalated 'quasi-freestanding' bilayer graphene on 6H-SiC(0001)
(Mg-QFSBLG) has many favorable properties (e.g., highly n-type doped,
relatively stable in ambient conditions). However, intercalation of Mg
underneath monolayer graphene is challenging, requiring multiple intercalation
steps. Here, we overcome these challenges and subsequently increase the rate of
Mg intercalation by laser patterning (ablating) the graphene to form
micron-sized discontinuities. We then use low energy electron diffraction to
verify Mg-intercalation and conversion to Mg-QFSBLG, and X-ray photoelectron
spectroscopy to determine the Mg intercalation rate for patterned and
non-patterned samples. By modeling Mg intercalation with the Verhulst equation,
we find that the intercalation rate increase for the patterned sample is
4.5$\pm$1.7. Since the edge length of the patterned sample is $\approx$5.2
times that of the non-patterned sample, the model implies that the increased
intercalation rate is proportional to the increase in edge length. Moreover, Mg
intercalation likely begins at graphene discontinuities in pristine samples
(not step edges or flat terraces), where the 2D-like crystal growth of
Mg-silicide proceeds. Our laser patterning technique may enable the rapid
intercalation of other atomic or molecular species, thereby expanding upon the
library of intercalants used to modify the characteristics of graphene, or
other 2D materials and heterostructures.
