Quantum Transport in DNA Heterostructures: Implications for Nanoelectronics

Understanding quantum transport through DNA-based heterostructures is a key to advancing the field of DNA nanoelectronics, where quantum interference would play a significant role. Electronic “barriers” and “wells” can be constructed in DNA using adenine–thymine (AT) and guanine–cytosine (GC) base pairs, respectively, as their ionization potentials differ significantly. We investigate the influence of the width of barriers and wells on hole transport. Density functional theory calculations are performed on energy-minimized DNA structures, followed by quantum transport calculations including decoherence. The device physics is probed by constructing a model Hamiltonian and selectively turning off long-range and interstrand interactions. Major outcomes of the study include the following: (1) DNA heterostructures complement the solid-state semiconductor counterparts; that is, conductance decreases sharply and marginally with an increase in barrier and well width, respectively; (2) quantum interference in DNA heterostructures is robust, as seen by clear peaks in the transmission resonance even with decoherence; (3) DNA conformation has a profound role in deciding the conductance of equivalent heterostructures; and (4) structural differences lead to closer HOMO energy levels and more delocalized states. As a result, transport can be efficient in some strands even with weaker π–π orbital overlap.