Stability diagrams and turnstile operations of single-common-gate triple-dot single-electron devices with outer junction capacitances different from inner ones

摘要

Single-common-gate triple-dot single-electron devices with outer and inner junction capacitances, C-a and C-b, respectively, have been investigated. By changing the C-a/C-b ratio, the stability regions and overlap regions between neighboring stability regions change their shapes and then the sequences of single-electron transfers around the overlap regions also change. The most interesting phenomenon is that the arrangement of the stability regions along the gate voltage axis, which normally follows the total excess electron number in the three islands, is partially inverted. That is, the electron configuration in the three islands with the smaller total excess electron number is stable with a higher gate voltage range. Even when in such a situation, the turnstile operation is still possible though the sequence of single-electron transfer changes. The inversion of the arrangement can be explained in terms of the charging energies. (C) 2015 The Japan Society of Applied Physics