Comparative evaluation of NANO transport properties for DNA nucleobase based molecular junction devices

The feasibility of electron transport conduction through a guanine base of DNA was investigated and then compared with another component of DNA, i.e., cytosine. A mathematical approach based on the jellium model using non-equilibrium Green's function combined with semi empirical extended Huckel theory was applied using the Atomistik Tool Kit. This was further used to measure significant transport parameters such as current, conductance, transmission spectra and the HOMO-LUMO gap of the suggested molecular system. An important revelation from our research work is that the cytosine-based molecular device exhibits metallic behavior with current ranging up to 70 μA, and hence establishes itself as a good conductor. On the other hand, the guanine-based device is comparatively less conductive, exhibiting current in the order of 3 μA. Another interesting observation about the guanine-based device is the visibility of a prominent negative differential resistance effect during the positive bias and a tunneling effect during negative bias. The uniform charge transfer through the cytosine device confirms its application as a molecular wire. The observations on the guanine-based device give better insights into its application as a memory device for nano-scale devices.