  We calculate tunneling conductance of normal metal and superconducting
topological insulator CuxBi2Se3 junctions for the possible pairing symmetries.
In the presence of gapless Andreev bound states (ABSs), the tunneling
conductance shows a zero-bias peak even for the three-dimensional full-gap
superconducting state. This zero-bias conductance peak stems from the
enhancement of the surface density of states induced by the surface-state
transition in momentum space.
