  We present a comprehensive study of the structural and electronic properties
of ultrathin films containing graphene layers synthesized by chemical vapor
deposition (CVD) based surface segregation on polycrystalline Ni foils then
transferred onto insulating SiO2/Si substrates. Films of size up to several
mm's have been synthesized. Structural characterizations by atomic force
microscopy (AFM), scanning tunneling microscopy (STM), cross-sectional
transmission electron microscopy (XTEM) and Raman spectroscopy confirm that
such large scale graphitic thin films (GTF) contain both thick graphite regions
and thin regions of few layer graphene. The films also contain many wrinkles,
with sharply-bent tips and dislocations revealed by XTEM, yielding insights on
the growth and buckling processes of the GTF. Measurements on mm-scale
back-gated transistor devices fabricated from the transferred GTF show
ambipolar field effect with resistance modulation ~50% and carrier mobilities
reaching ~2000 cm^2/Vs. We also demonstrate quantum transport of carriers with
phase coherence length over 0.2 $\mu$m from the observation of 2D weak
localization in low temperature magneto-transport measurements. Our results
show that despite the non-uniformity and surface roughness, such large-scale,
flexible thin films can have electronic properties promising for device
applications.
