Using single-electron box arrays for voltage sensing applications

Single-electron tunneling transistors (SETs) and boxes (SEBs) belong to the family of charge-sensitive electronic devices based on the phenomenon of Coulomb blockade. An SEB is a two-terminal device composed of “leaky,” C j, and “non-leaky,” C g, nanoscaled capacitors in series. At low temperatures, the charge at the common node is quantized and can only be changed near energy-population degeneracy points, resulting in periodic oscillations of the SEB admittance as a function of voltage applied to C g. In comparison to the SETs, SEBs have higher operating temperature, are electrostatic discharge tolerant, and have a much smaller footprint. To monitor the SEB admittance, Radio Frequency reflectometry can be used. To improve the signal-to-noise ratio, limited by the small change in admittance in an SEB, multiple devices sharing the same source and gate electrodes are connected in parallel to form arrays of SEBs. Due to unavoidable random offset charges, the signal boost for an array of N SEBs is expected to be ∼ N. We experimentally demonstrate that by carefully choosing the operating point, the response to the voltage on the sensing gate can be enhanced, for small arrays scales, by a factor approaching N and, thus, provides a method by which these devices can be used in practical sensing applications, such as a scanning probe.