Abstract
Graphene field-effect transistors (GFET) hold promise in biomolecule sensing due to the outstanding properties of graphene materials. Charges in biomolecules are transduced into a change in the GFET current, which allows real-time monitoring of the biomolecule concentrations. Here we theoretically evaluate the performance of GFET based real-time biomolecule sensing, aiming to better understand the width-scaling limit in GFET based biosensors. In particular, we study the effect of the channel-width and the chirality on FET sensitivity by taking the percentage change of the FET current per unit charge density as the sensing signal. Firstly, GFETs made of graphene nanoribbons (GNR) and graphene sheets (GS) show comparable sensing signals to each other when gated at 1011 – 1012 cm-2 carrier densities. Sensing signals in GNRs are enhanced when gated near the sub-band thresholds, and increase their values in wider GNRs due to the change in device conductance and quantum capacitance. Secondly, the GNR chirality is found to fine tune the sensing signals. Armchair GNRs with smaller energy bandgaps appear to have an enhanced sensing signal close to 1011 cm-2 carrier densities. These results may help understand the scaling limit in GFET based biosensors along the width direction, and shed light on forming all-electrical bio-arrays.
Highlights
Field-effect transistor (FET) based biomolecular sensors transduce the biomolecule charges at the affinity of FET gate or FET channel into a change of the channel current or THE threshold voltage.[1,2,3]
We present a theoretical framework to evaluate the performance of GFET based realtime biomolecule sensing, which results from the transport properties of graphene
Our data suggest that GNR-FETs with optimized channel width and chirality have comparable performance to that in GS-FETs, a key result that allows researchers to scale down the channel-width of GFET based biosensors
Summary
Field-effect transistor (FET) based biomolecular sensors transduce the biomolecule charges at the affinity of FET gate or FET channel into a change of the channel current or THE threshold voltage.[1,2,3]. Effect of channel-width and chirality on graphene field-effect transistor based realtime biomolecule sensing
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