Double gate operation of metal nanodot array based single electron device

Abstract

Multidot single-electron devices (SEDs) can enable new types of computing technologies, such as those that are reconfigurable and reservoir-computing. A self-assembled metal nanodot array film that is attached to multiple gates is a candidate for use in such SEDs for achieving high functionality. However, the single-electron properties of such a film have not yet been investigated in conjunction with optimally controlled multiple gates because of the structural complexity of incorporating many nanodots. In this study, Fe nanodot-array-based double-gate SEDs were fabricated by vacuum deposition, and their single-electron properties (modulated by the top- and bottom-gate voltages; VT and VB, respectively) were investigated. The phase of the Coulomb blockade oscillation systematically shifted with VT, indicating that the charge state of the single dot was controlled by both the gate voltages despite the metallic random multidot structure. This result demonstrates that the Coulomb blockade oscillation (originating from the dot in the multidot array) can be modulated by the two gates. The top and bottom gates affected the electronic state of the dot unevenly owing to the geometrical effect caused by the following: (1) vertically asymmetric dot shape and (2) variation of the dot size (including the surrounding dots). This is a characteristic feature of a nanodot array that uses self-assembled metal dots; for example, prepared by vacuum deposition. Such variations derived from a randomly distributed nanodot array will be useful in enhancing the functionality of multidot devices.

Characteristics of the single-electron conduction properties of randomly distributed metal nanodot arrays

“…25,38,[42][43][44] In our previous studies on random-array SEDs composed of Fe nanodots formed by vacuum deposition, the oscillation characteristics originating from a single dot could be observed in a certain Fe thickness range, 42) and we discussed the logic gate operation using the double-gate device. 44) Here, the microstructural dot arrangement (e.g. the dot number density, dot size, and inter-dot distance) must play a key role in obtaining the SED operations.…”

“…Another type of study of SEDs has been performed using random dot arrays in which a number of nanodots are randomly distributed, for example, dispersion of chemically synthesized nanodots or self-assembled dot growth in thin metal films fabricated by vacuum deposition. 2,25,[34][35][36][37][38][39][40] Although there was a concern that the CB properties from individual dots would be masked because of the complex dot arrangement forming numerous conduction paths, the CB operation was successfully detected, 25,[34][35][36][37][38][39][40][41][42][43][44] and clear oscillation has even been demonstrated. 25,38,[42][43][44] In our previous studies on random-array SEDs composed of Fe nanodots formed by vacuum deposition, the oscillation characteristics originating from a single dot could be observed in a certain Fe thickness range, 42) and we discussed the logic gate operation using the double-gate device.…”

“…2,25,[34][35][36][37][38][39][40] Although there was a concern that the CB properties from individual dots would be masked because of the complex dot arrangement forming numerous conduction paths, the CB operation was successfully detected, 25,[34][35][36][37][38][39][40][41][42][43][44] and clear oscillation has even been demonstrated. 25,38,[42][43][44] In our previous studies on random-array SEDs composed of Fe nanodots formed by vacuum deposition, the oscillation characteristics originating from a single dot could be observed in a certain Fe thickness range, 42) and we discussed the logic gate operation using the double-gate device. 44) Here, the microstructural dot arrangement (e.g.…”