The Gate Voltage Control of Long DNA Coherent Transport on Insulator Surface

We investigate the coherent transport properties of a DNA chain on a substrate which is subjected to a uniform electric field perpendicular to the surface. On the basis of the effective tight-binding model which simulates charge transport through DNA, the transmission coefficient, Lyapunov exponent, and localization length are numerically calculated by using the transfer-matrix method. It is found that an isolated extended state may appear at the Fermi level for a certain gate voltage when the interaction strength between the chain and the substrate is position dependent but independent of the base-pair sequence, leading to the gate voltage induced Metal-insulator transition (MIT). Moreover, conductance and current-voltage characteristics are also calculated. The relationship of Lyapunov exponent distribution to the current-voltage characteristics is discussed. Two different conduction mechanisms are proposed depending on effectively delocalized states and isolated extended states, respectively. These results may provide perspectives for experimental work aimed at controlling charge transport through DNA-based nanodevices.