Thickness and low-temperature conductivity of DNA molecules

We argue that interaction between molecules and substrate is a key parameter which determines the conducting or insulating behavior of DNA molecules. In this letter, we show that strongly deformed DNA molecules deposited on a substrate, whose thickness is less than half the native thickness of the molecule, are insulating, whereas molecules keeping their native thickness are conducting down to very low temperature with a non-ohmic behavior characteristic of a 1D conductor with repulsive electron-electron interactions. (C) 2004 American Institute of Physics.