  The magneto-transport properties in Sulfur doped Bi2Se3 are investigated. The
magnetoresistance (MR) decreases with increase of S content and finally for 7%
(i.e. y=0.21) S doping the magnetoresistance becomes negative. This negative MR
is unusual as it is observed when magnetic field is applied with the
perpendicular direction to the plane of the sample. The magneto-transport
behavior shows the shubnikov-de hass (SdH) oscillation indicating the
coexistence of both surface and bulk states. The negative MR has been
attributed to the bulk conduction.
