Silicon nanowires (SiNWs), fabricated via a top-down approach and then functionalized with\nbiological probes, are used for electrically-based sensing of breast tumor markers. The SiNWs,\nfeaturing memristive-like behavior in bare conditions, show, in the presence of biomarkers,\nmodified hysteresis and, more importantly, a voltage memory component, namely a voltage gap.\nThe voltage gap is demonstrated to be a novel and powerful parameter of detection thanks to its\nhigh-resolution dependence on charges in proximity of the wire. This unique approach of\nsensing has never been studied and adopted before. Here, we propose a physical model of the\nsurface electronic transport in Schottky barrier SiNW biosensors, aiming at reproducing and\nunderstanding the voltage gap based behavior. The implemented model describes well the\nexperimental Iââ?¬â??V characteristics of the device. It also links the modification of the voltage gap to\nthe changing concentration of antigens by showing the decrease of this parameter in response to\nincreasing concentrations of the molecules that are detected with femtomolar resolution in real\nhuman samples. Both experiments and simulations highlight the predominant role of the\ndynamic recombination of the nanowire surface states, with the incoming external charges from\nbio-species, in the appearance and modification of the voltage gap. Finally, thanks to its\ncompactness, and strict correlation with the physics of the nanodevice, this model can be used to\ndescribe and predict the Iââ?¬â??V characteristics in other nanostructured devices, for different than\nantibody-based sensing as well as electronic applications.
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