  We have developed a method for depositing graphene monolayers and bilayers
with minimum lateral dimensions of 2-10 nm by the mechanical exfoliation of
graphite onto the Si(100)-2x1:H surface. Room temperature, ultra-high vacuum
(UHV) tunnelling spectroscopy measurements of nanometer-sized single-layer
graphene reveal a size dependent energy gap ranging from 0.1-1 eV. Furthermore,
the number of graphene layers can be directly determined from scanning
tunnelling microscopy (STM) topographic contours. This atomistic study provides
an experimental basis for probing the electronic structure of nanometer-sized
graphene which can assist the development of graphene-based nanoelectronics.
