Effect of antibound states in single barrier tunneling -: art. no. 024103

It is demonstrated that for very thin or very shallow rectangular barriers the transmission amplitude possesses an antibound pole situated very close to threshold energy. The transmission coefficient and the delay time at very low incidence energies may be expressed analytically in terms of the antibound pole contribution, which accounts, respectively, for the enhancement of the transmittivity to almost a unity value and for the large delay time exhibited by these systems. The large delay time caused by the antibound pole represents a type of "trapping" mechanism different from that of resonant tunneling.