ИСТИНА

Contemporary microelectronics is very close to the limits of miniaturization of traditional electronic components. In this regard, special attention is paid to promising alternative approaches to their creation. The creation of molecular transistor, that is capable to operate in single-electron regime at room temperature, is an example of such approach [1]. This is very important for many applications, especially for chemical and biosensors [2]. The basis of the molecular transistor is a system of thin film metal electrodes separated by a gap. The gap size should be less than a few nanometers. The creation of molecular transistor electrodes with a gap between them less than a few nanometers is one of the main problems. This problem cannot be solved using traditional electron beam lithography (EBL). Currently, the most promising solution is the use of the electromigration [3]. Electrodes separated by a gap less than 2-3 nanometers can be obtained using electromigration. Thin (less than 20 nm) and narrow (less than 90 nm) nanowire is needed to provide controllable electromigration process. However, the adhesion between the nanowire and the substrate shouldn’t be too strong to provide the electromigration but it should be enough to provide lithography operations. In this work the technique of electrodes formation of single electron transistor suitable for high temperature single electron sensors satisfying these conditions is described. For the preparation of nanowire samples suitable for electromigration a layer of SiO2 was evaporated on a standard Si wafer of 80 mm diameter to make an insulating layer on a substrate using Leybold Z400. Then a scriber was used to make chips with dimensions of 10´10 mm2. Contact pads (to connect measuring equipment to the chip) and thin film metal (gold) electrodes (to connect nanowires to the pads) were built using photo - lithography. Nanowires for electromigration were built in the center of the chip (region of 80´80 μm2) using EBL. To provide the appropriate adhesion between the substrate and nanowires thin Al2O3 layer was used. All metal and Al2O3 layers were evaporated using Leybold L560. As a result, samples containing 16 nanowires on each chip with width in range of 60-80 nm and resistance of a few kOhm were obtained. Such properties provides optimal regime for electromigration and proves the appropriate quality of films. Thus, the technique of the creation of single-electron high temperature molecular transistor electrodes was developed. Such electrodes are appropriate to the creation of high temperature single electron transistor with an island of 2-3 nm size. Optimal parameters for thin and narrow metal nanowires were defined. Samples of nanowires that provide obtaining of sub-5 nm gaps between electrodes were made. This work was supported by RFBR (projects 12-07-00816-a, 10-07-00712-), Federal Target Program “Scientific and teaching specialists of innovative Russia for 2009-13” (contracts 02.740.11.0229,14.740.11.0389, 16.740.11.0020, 14.740.11.0370). 1. K.K. Likharev, Proc. IEEE 87, p.606, 1999. 2. H. Zhang, R. Barsotti, F. Stellacci and J. Thong, Small 5, p.2797, 2009. 3. H. Park, A.K.L. Lim, A.P. Alivisatos, J. Park, P.L. McEuen, Appl. Phys. Lett., 75, pp.301-303, 1999.