Elemental charge sensitivity of liquid-gated carbon nanotube transistors

Electron transport in carbon nanotubes (CNTs) is extremely sensitive to electrostatic~perturbations, suggesting that CNT field-effect transistors (FETs) are promising candidates for~low-power digital switches and high-performance sensors. In this work,~we show that the perturbation caused by a single elemental charge~strongly affects the room temperature conductance of a CNT FET. We make~use of naturally occurring activated charge traps in SiO$_{\mathrm{2}}$ to observe~random telegraph signals which reach 20{\%} of the baseline signal. Our~measurements are made in a liquid-gated environment where these~telegraph signals are persistent over long time scales and tunable by~gate-voltage. Gate-voltage dependence is compared to non-equilibrium~Greens function calculations. We verify the theoretically predicted~relationship between signal magnitude and gate voltage, and show that~this relationship differs dramatically from predictions based simply on~transconductance. Our measurements confirm the exciting possibility of~detecting elemental charges at room temperature, and verify a~theoretical framework for predicting conductance changes due to motion~of an elemental charge near a CNT FET.