Wide bandgap semiconductor from a hidden 2D incommensurate graphene phase

• Main Authors: Conrad, Matthew, Wang, Feng, Nevius, Meredith, Jinkins, Katherine, Celis, Arlensiú, Nair, Maya, Taleb-Ibrahim, Amina, Tejeda, Antonio, Garreau, Yves, Vlad, Alina, Coati, Alessandro, Miceli, Paul, Conrad, Edward
• Format: Journal Article
• Language: English
• Published: 10-10-2016
• Subjects: Physics - Mesoscale and Nanoscale Physics
• DOI: 10.48550/arxiv.1610.02114

Producing a usable semiconducting form of graphene has plagued the
development of graphene electronics for nearly two decades. Now that new
preparation methods have become available, graphene's intrinsic properties can
be measured and the search for semiconducting graphene has begun to produce
results. This is the case of the first graphene "buffer" layer grown on
SiC(0001) presented in this work. We show, contrary to assumptions of the last
forty years, that the buffer graphene layer is not commensurate with SiC. The
new modulated structure we've found resolves a long standing contradiction
where ab initio calculations expect a metallic buffer, while experimentally it
is found to be a semiconductor. Model calculations using the new incommensurate
structure show that the semiconducting $\pi$-band character of the buffer comes
from partially hybridized graphene incommensurate boundaries surrounding
unperturbed graphene islands.