rf-electrometer using a carbon nanotube resonant tunneling transistor

We have studied resonant tunneling transistors (RTT) made of single-walled carbon nanotube quantum dots in the Fabry–Pérot regime. We show sensitivity to input charge as high as $5×10−6e/Hz1/2$ with a carrier frequency of 719 MHz at 4.2 K. This result is comparable to the best values of charge sensitivity so far reported for radio frequency single electron transistors (rf-SET). Unlike SETs, whose operating temperature is limited as Coulomb blockade vanishes as $1/T$⁠, a RTT can operate at higher temperatures, since the dephasing length $lϕ∝1/T2/3$⁠.