  We investigated the magnetotransport properties of Fe-doped topological
insulator Sb1.96 Fe0.04Te3 single crystals. With doping, the band structure
changes significantly and multiple Fermi pockets become evident in the
Shubnikov-de Haas oscillations, in contrast to the single frequency detected
for pure Sb2Te3. Using complementary density functional theory calculations, we
identify an additional bulk hole pocket introduced at the {\Gamma} point which
originates from the chemical distortion associated with the Fe-dopant.
Experimentally, both doped and undoped samples are hole-carrier dominated,
however, Fe doping also reduces the carrier density and mobility. The angle
dependent quantum oscillations were analyzed to characterize the complex Fermi
surface and isolate the dimensionality of each SdH feature. Among the
components, at least two pockets possess 2D-like behavior according to their
rotational dependence. These results indicate a complex interplay of hybridized
dopant bands with the bulk and surface topological electronic structure.
