  The recent discovery of excellent thermoelectric properties and topological
surface states in SnTe-based compounds has attracted extensive attention in
various research areas. Indium doped SnTe is of particular interest because,
depending on the doping level, it can either generate resonant states in the
bulk valence band leading to enhanced thermoelectric properties, or induce
superconductivity that coexists with topological states. Here we report on the
vapor deposition of In-doped SnTe nanowires and the study of their surface
oxidation and thermoelectric properties. The nanowire growth is assisted by Au
catalysts, and their morphologies vary as a function of substrate position and
temperature. Transmission electron microscopy characterization reveals the
formation of amorphous surface in single crystalline nanowires. X-ray
photoelectron spectroscopy studies suggest that the nanowire surface is
composed of In2O3, SnO2, Te and TeO2 which can be readily removed by argon ion
sputtering. Exposure of the cleaned nanowires to atmosphere yields rapid
oxidation of the surface within only one minute. Characterizations of
electrical conductivity {\sigma}, thermopower S, and thermal conductivity
\k{appa} were performed on the same In-doped nanowire which shows suppressed
{\sigma} and \k{appa} but enhanced S yielding an improved thermoelectric figure
of merit ZT than the undoped SnTe.
