  We report suppression of superconductivity in Bi4O4S3 compound by Se doping
at S site. Bulk polycrystalline samples are synthesized by solid state reaction
route. The Rietveld refined of XRD data of all the studied samples show that
the same are crystallized in tetragonal I4/mmm space group with slightly
increased c lattice constant with the Se doping. Superconductivity is observed
at below 4.5 K in both dc magnetization and resistivity with temperature
measurements for all Bi4O4S3-xSex (x = 0, 0.03, 0.09 and 0.15) samples, though
the same is decreased slightly with increase in Se content. The upper critical
field of the Bi4O4S3 is estimated from resistivity under magnetic field [R(T)H]
measurements of up to 2T (Tesla), and the same decreases for Se doped samples.
The flux flow activation energies being obtained by fitting to the the
Arrhenius equation are 18.60 meV for Bi4O4S3, 13.69 meV for Bi4O4S2.97Se0.03
and 13.16 meV for Bi4O4S2.85Se0.15 samples in applied magnetic field of 200 Oe.
In conclusion the S site Se substitution showed detrimental effect on
superconductivity of Bi4O4S3.
