Transmission singularities in resonant electron tunneling through double complex potential barrier

Tunneling of electrons through a barrier with complex potential is investigated. We focus on two cases, symmetric double rectangular barrier and double delta potential barrier, and give expressions for resonant transmission probability for both cases. Expressions for reflection amplitude and absorption are also obtained in the case of delta potential. It will be shown that for given incident particle energy, parameters of the potential structure can be obtained so that the resonant transmission probability approaches infinity. The phenomenon of infinite transmission occurs only for potentials which have positive imaginary part.