  The intercalation of an oxide barrier between graphene and its metallic
substrate for chem- ical vapor deposition is a contamination-free alternative
to the transfer of graphene to dielectric supports, usually needed for the
realization of electronic devices. Low-cost pro- cesses, especially at
atmospheric pressure, are desirable but whether they are achievable remains an
open question. Combining complementary microscopic analysis, providing
structural, electronic, vibrational, and chemical information, we demonstrate
the spontaneous reactive intercalation of 1.5 nm-thick oxide ribbons between
graphene and an iridium substrate, at atmospheric pressure and room
temperature. We discover that oxygen-containing molecules needed for forming
the ribbons are supplied through the graphene wrinkles, which act as tunnels
for the efficient diffusion of molecules entering their free end. The
intercalated oxide ribbons are found to modify the graphene-support
interaction, leading to the formation of quasi-free-standing high quality
graphene whose charge density is modulated in few 10-100 nm-wide ribbons by a
few 10^12 cm-2, where the inelastic optical response is changed, due to a
softening of vibrational modes - red-shifts of Raman G and 2D bands by 6 and 10
cm-1, respectively.
