  We report the transport properties of mechanically exfoliated few-layer
SnSe$_{2}$ flakes, whose mobility is found with four probe measurements to be ~
85 cm$^{2}$V$^{-1}$s$^{-1}$ at 300 K, higher than those of the majority of
few-layer transitional metal dichalcogenides (TMDs). The mobility increases
strongly with decreased temperature, indicating a phonon limited transport. The
conductivity of the semiconducting SnSe$_{2}$ shows a metallic behavior, which
is explained by two competing factors involving the different temperature
dependence of mobility and carrier density. The Fermi level is found to be 87
meV below the conduction band minima (CBM) at 300 K and 12 meV below the CBM at
78 K, resulting from a heavy n-type doping. Previous studies have found
SnSe$_{2}$ field-effect transistors (FETs) to be very difficult to turn off. We
find the limiting factor to be the flake thickness compared with the maximum
depletion width. With fully depleted devices, we are able to achieve a current
on-off ratio of ~10$^{5}$. These results demonstrate the great potential of
SnSe2 as a two dimensional (2D) semiconducting material and are helpful for our
understanding of other heavily doped 2D materials.
