A strongly asymmetric single-electron transistor operating as a zero-biased electrometer

We have studied a strongly asymmetric Al single-electron transistor with R₁ ? R₂ and C₁ ? C₂, where R_{1, 2} and C_{1, 2} are the tunnel resistances and capacitances of the first and second junction respectively. Due to the asymmetry in its electric parameters leading to strong asymmetry of the nonlinear I–V curve at zero bias (V = 0), the transistor demonstrated a remarkable current response to an AC signal at the values of the gate charge Q₀ close to (n + 1/2)e, where n is integer. A rather delicate regime of the transistor operation (V ? e/C_Σ) being important for unperturbed measurements was examined. The measured curves are in good agreement with a model based on the orthodox theory of single electron tunneling. This specific zero bias regime of an asymmetric transistor opens new opportunities for a single-electron transistor as an ultrasensitive charge/field sensor.