Simultaneous arrayed formation of single-electron transistors using electromigration in series-connected nanogaps

Mitsuki Ito,Jun-Ichi Shirakashi,Mamiko Yagi,Moe Shimada

doi:10.1063/1.5043449

Abstract

A field-emission-induced electromigration method (activation) is reported for integrating single-electron transistors operating at T = 298 K. The field emission currents between the two opposite electrodes of each series-connected nanogap are tuned to accumulate Ni atoms within the gaps. For ten series-connected nanogaps, the resistance (VD/ID), obtained using the current-voltage (ID-VD) properties of these nanogaps during the activation procedure, is observed to decrease on activation. As a result, island structures are formed within the gaps, and the nanogap-based single-electron transistors can be integrated, when atom migration occurs at the tip of each nanogap electrode. After activating the ten series-connected nanogaps with a preset current, IS = 1 nA, current suppression (representative of coulomb blockade) is not observed in the fabricated devices. On the other hand, coulomb blockade, which depicts the charging and discharging of the nanoislands, can be observed at room temperature, after activation with a preset current, IS = 150 nA. Furthermore, the modulation properties of the coulomb blockade voltage by the gate voltage are also determined at room temperature. These results experimentally demonstrate the arrayed formation of ten single-electron transistors operating at room temperature, constituting a significant step toward the practical realization of single-electron-transistor-based systems.

Highlights

For the practical application of single-electron devices, such as single-electron transistors (SETs), it is crucial to integrate them with a high process yield
Several researches have been undertaken for the fabrication of SETs using nanofabrication schemes, which involve focused ion beam deposition[1,2] or special techniques and processes, such as the electrostatic trapping of single conducting nanoparticles between nanoelectrodes,[3,4] electromigration-induced breaking of thin metal wires defined by electron-beam lithography,[5,6,7,8,9] and hydrogen-resist lithography.[10]
Metal-based SETs operating at room temperature exhibit drain currents with amplitudes in the femtoampere range due to the small size of the metal island and narrow area of the tunnel junctions.[31]

Summary

INTRODUCTION

For the practical application of single-electron devices, such as single-electron transistors (SETs), it is crucial to integrate them with a high process yield. Field emission has been reported for reconstructing the atomic geometry at the nanogap electrode tip.[11,12,13,14] In addition, Araidai has theoretically investigated atom migration in electron field emission using the first-principles calculations.[15] The changes in discontinuous thin metal films have been reported by the application of modest electric fields.[16] Using these phenomena, we propose a simple method for the fabrication of quantum tunneling devices composed of nanogaps, such as planar-type ferromagnetic tunnel junctions and SETs.[20,21,22,23,24]. For the practical application of SETs, the formation of SET arrays is investigated, using the activation method

EXPERIMENTAL DETAILS

RESULTS AND DISCUSSION

CONCLUSION