  Circumbinary planets have been observed at orbital radii where binary
perturbations may have significant effects on the gas disk structure, on
planetesimal velocity dispersion, and on the coupling between turbulence and
planetesimals. Here, we note that the impact of all of these effects on planet
formation is qualitatively altered if the circumbinary disk structure is
layered, with a non-turbulent midplane layer (dead zone) and strongly turbulent
surface layers. For close binaries, we find that the dead zone typically
extends from a radius close to the inner disk edge up to a radius of around
10-20 au from the centre of mass of the binary. The peak in the surface density
occurs within the dead zone, far from the inner disk edge, close to the snow
line, and may act as a trap for aerodynamically coupled solids. We suggest that
circumbinary planet formation may be easier near this preferential location
than for disks around single stars. However, dead zones around wide binaries
are less likely and hence planet formation may be more difficult there.
