Oscillatory dependence of tunneling conductance on the barrier thickness

Oscillatory dependence of tunneling conductance on the barrier thickness is investigated theoretically for the metal/insulator/metal junctions. The tunneling transmission is expressed with the reflection and the transmission amplitudes of each separated metal/insulator interface and the wavevectors inside the barrier. An analytical formula is obtained for the tunneling conductance. The oscillatory behavior of the tunneling conductance is possible with the complex band structure of the insulator. The oscillation period is determined not directly from the real part of the complex wavevector in the insulator, but from the extremal complex spanning vector of the complex Fermi surface of the insulator.