  Superconducting proximity junctions made of topological insulator (TI)
nanoribbons (NRs) provide a useful platform for studying topological
superconductivity. We report on the fabrication and measurement of Josephson
junctions (JJs) using Sb doped Bi$_2$Se$_3$ NRs in contact with Al electrodes.
Aharonov$-$Bohm and Altshuler$-$Aronov$-$Spivak oscillations of the axial
magneto-conductance of TI NR were observed, indicating the existence of
metallic surface states along the circumference of the TI NR. We observed the
supercurrent in the TI NR JJ and subharmonic gap structures of the differential
conductance due to multiple Andreev reflections. The interface transparency of
the TI NR JJs estimated based on the excess current reaches $\tau$ = 0.83,
which is among the highest values reported for TI JJs. The temperature
dependence of critical current is consistent with the short and ballistic
junction model confirming the formation of highly transparent superconducting
contacts on the TI NR. Our observations would be useful for exploring
topological Josephson effects in TI NRs.
