ИСТИНА

Continuing progress in miniaturization of basic components in electronic circuits allows to search for new physical phenomena as a basis for a future nanoelectronics. One of such effects taking place on a nanometer scale is a correlated tunneling of electrons. The most simple device that allows to observe an effect is a single-electron transistor [1]. It consists of two electrodes with a central conducting island between them separated from each other by tunnel junctions and a third electrode capacitively coupled with an island. The effect can be destroyed by thermal or quantum fluctuations. So the transistor can operate only if the following condition is performed:e^2/2c>>KT (1), C is total capacitance of SET, T is operating temperature. It's clear that a room temperature applications of the device requires an extremely low capacitance value (10-19-10-18 F). It means that the island must be less than 3 nm in diameter. In this work we report about formation of single-electron transistors based on single gold nanoparticles functionalized by octanethiol (2 – 4 nm, commercially available). Electrodes of the devices were formed using a standard electron-beam lithography combined with an electromigration technique [2]. The electromigration effect was used to form nanometer scale gaps in 60-70 nm wide and 14 nm thick nanowires. Nanoparticles were placed into gaps using a self-assembling from the toluene solution. A concentration of the solution was chosen empirically by diluting the initial solution for maximize probability to find a single nanoparticle in the gap. The presence of a nanoparticle in the gap was established by electrical measurements in a liquid nitrogen temperature. We found out that scanning electron microscope imaging of the gaps dramatically changes their electrical characteristics, so images of the resulting structures were obtained only when all other investigations were completed. Obtained systems were characterized by measuring a bias current (I) as a function of both drain (Vt) and gate voltage (Vg). Using this data 2D stability diagrams (I(Vt,Vg)) were constructed for wide range of operating temperatures. A Coulomb diamonds can be seen on diagrams clearly demonstrate a single-electron character of an electron transport. The maximal obtained value of a Coulomb blockade that corresponds to the charging energy of the nanoparticle is almost 300 mV. It is more than values available in literature for the similar system [3]. This result was achieved by using the smaller nanoparticles. It allows to investigate a single-electron systems potential for very practically important high-temperature applications. This work was supported by "Russian fond of basic research" (grants № 12-07-00816-a, № 14-07-31328)