Theoretical Prescriptions for Improving Conductances of Short DNA Segments Sandwiched between Metal Electrodes

Abstract

In the band-resonant tunneling regime, we studied by theoretical simulations the effects of mechanical deformation and gate modulation on the electronic transport properties through short (34 Å-long) deoxyribonucleic acid (DNA) segments sandwiched between two aluminum electrodes. We found that the structural deformation of DNA, such as the tilting of the guanine (G)–cytosine (C) base pairs, causes the upper shifts of their occupied energy levels. When these energy levels cross the Fermi level and the excess charge flows out to the electrodes, the hole is injected into the G–C base pairs, dominantly into the guanine array. In addition, we found that by applying the negative gate bias voltages, the occupied energy levels are raised across the Fermi level and the hole is injected into the guanine array. By these carrier injections, the conductances of the short DNA molecule improve dramatically in both cases.