Title: A single electron transistor nanopore as toxic gas sensor: First principles investigation

Abstract

The single electron transistor (SET) is a three terminal device similar to that of a MOS transistor, and contains a source terminal for the release of electrons, a drain terminal for the receipt of electrons, and a gate terminal to control the flow of electrons through the quantum dot. The unique Coulomb blockade phenomenon of SET enables the one after another tunnelling of electrons from source to drain via the quantum dot, which is highly sensitive to the surroundings making it a great choice for sensing applications. The present work utilizes a SET nanopore as a toxic gas sensor to obtain the electronic fingerprints of detection for the highly toxic hydrogen cyanide (HCN), phosgene (COCl2), methyl chloride (CH3Cl) and vinyl chloride (C2H3Cl) gases in the vicinity of density functional theory (DFT) based first-principles approach. The gold electrodes with a work function of 5.28 eV and gate oxide with a dielectric constant of 10ε0 are considered. The sensing mechanism is demonstrated with the help of various outputs obtained from the SET device viz. total energy plotted w.r.t gate voltages, charge stability diagrams, horizontal line scans, vertical line scans, and charging energies. The SET nanopore offers unique electronic fingerprints for these toxic gases in terms of degeneracy points, operating bias voltage ranges for single electron transfer, and charging energies. The degeneracy points, where the SET device can enter ON state are different for all the 4 toxic gases. The vertical line scans reveal distinct operating bias voltage ranges corresponding to single electron transfer for these toxic gases. The charging energies are unique for each of the targeted toxic gases and their orientations. The results portray the modelled nanopore as an effective sensor for the detection of these toxic gases.