  Structural and thermoelectric properties of metallic and semiconducting
Sb2Te3 are reported. X-Ray diffraction and Raman spectroscopy studies reveal
that semiconducting sample have higher defect density. Nature and origin of
possible defects are highlighted. Semiconducting Sb2Te3 hosts larger numbers of
defects, which act as scattering center and give rise to the increased value of
resistivity, thermopower and power factor. Thermopower data indicates p-type
nature of the synthesized samples. It is evidenced that the surface states are
often mixed with the bulk state, giving rise to metallicity in Sb2Te3. Role of
different scattering mechanism on the thermoelectric property of Sb2Te3 is
discussed.
