  We show that it is possible to deposit, by mechanical exfoliation on SiO2/Si
wafers, atomically thin mica flakes down to a single monolayer thickness. The
optical contrast of these mica flakes on top of a SiO2/Si substrate, which
depends on their thickness, the illumination wavelength and the SiO2 substrate
thickness, can be quantitatively accounted for by a Fresnel law based model.
The preparation of atomically thin insulating crystalline sheets will enable
the fabrication of ultrathin defect-free insulating substrates, dielectric
barriers or planar electron tunneling junctions. Additionally, we show that
few-layer graphene flakes can be deposited on top of a previously transferred
mica flake. Our transfer method relies on viscoelastic stamps, as those used
for soft lithography. A Raman spectroscopy study shows that such an all-dry
deposition technique yields cleaner and higher quality flakes than conventional
wet-transfer procedures based on lithographic resists.
