Dependence of the tunneling conductance on the barrier thickness: effects of the complex-band structure

The dependence of tunneling conductance on the barrier thickness was investigated theoretically by using a tight-binding model. In order to calculate the tunneling conductance, full-band calculations were carried out with a model tunnel junction. In addition to an exponential decay, it was shown that the tunneling conductance may oscillate strongly as a function of the barrier thickness due to the complex-band structure of the barrier. The relation between the complex Fermi surface of the barrier and the oscillation period of the tunneling conductance was examined. The oscillation of the tunnel conductance is affected by the matching between the metal and the barrier bands.