Yu.V. Nastaushev

A technique for fabricating Au/Ti micro- and nanotubes

For the first time, Au/Ti micro- and nanotubes were prepared by rolling initially planar, strained Au/Ti bifilms, freed from the Si substrates by wet selective etching of underlying Al sacrificial layers. Conducting metal tubes with diameters ranging from 20 µm to 40 nm were made from 10 µm wide and 10 cm long metal strips lithographically defined on Si substrates. Also, arrays of tubes rigidly attached to the substrate by unrolled parts of the film were obtained. Fully detached tubes could be bent to form sharp angles or loops without mechanical failure, due to their high plasticity. The shape and electric conductivity of the Au/Ti micro- and nanotubes were found to remain unchanged over a more than two-year long storage in ambient air.

Negative differential magnetoresistance and commensurability oscillations of two-dimensional electrons in a disordered array of antidots

Negative linear magnetoresistance of two-dimensional (2D) electrons have been found in a disordered array of antidots. The authors suggest that trajectories that roll along the array of antidots exist in a magnetic field. These trajectories have a mean free path larger than the average value for electrons with ordinary diffusion.

Fluorescently labeled single-walled carbon nanotubes and their hybrids with oligonucleotides

The approach to the preparation of fluorescein-labeled single-walled carbon nanotubes was proposed. The investigation of physico-chemical properties of obtained modified nanotubes was performed. The method of the design of non-covalent hybrids of fluorescein-labeled carbon nanotubes with nucleic acid fragments containing pyrene residues at 5′-termini was developed. This method is based on stacking interactions of pyrene residues with carbon nanotubes surface. The effect of carbon nanotubes functionalization type on the efficacy of sorption of pyrene conjugates of oligonucleotides was examined.

Negative magnetoresistance and anomalous diffusion of two-dimensional electrons in a disordered array of antidots

Abstract Negative linear magnetoresistance of two-dimensional (2D) electrons in a disordered array of antidots has been found. The existence in a magnetic field of trajectories which roll along the array of antidots was suggested. These trajectories have a mean free path larger than the average value for electrons with ordinary diffusion.

Magnetoresistance oscillations in a two-dimensional electron gas with a periodic array of scatters

The authors have studied the magnetoresistance of a two-dimensional electron gas in an array of antidots with periodicities in the range 0.6-1.3 mu m. In weak magnetic fields (B<10 mT) they have observed magnetoresistance oscillations with a period of hc/2eS, where S is the area of the cell enclosed by the ballistic trajectories of the electrons. In magnetic fields of B<100 mT, the oscillations originating from the commensurability of the cyclotron radius and the lattice period were studied. The behaviour of some oscillations was found to disagree with the classical model of pinned electron orbits in magnetic fields.

Magnetoresistance of two-dimensional electrons in a lateral lattice of antiwires

Abstract Magnetoresistance of two-dimensional (2D) electrons in potential superlattice which has a form of stripes with length of 5–10 μm and width 0.15–0.2 μm etched through heterostructures GaAs/AlGaAs has been studied. Magnetoresistance oscillations were found with positions of maxima depending on the length of stripes. The negative magnetoresistance due to weak localization effects was studied. The temperature dependence of the coherence length of electrons was not in agreement with the theory for the two-dimensional or one-dimensional case.

Absence of delocalised states in a 2D electron gas in a magnetic field below ωcτ=1

Abstract The quantum Hall liquid-Hall insulator transition has been studied using a gate-controlled periodical lattice of antidots. This system allows us to probe deep into the phase-space of the transition at both low and high magnetic fields. It is shown, that the transition occurs when the longitudinal and Hall conductivities are equal to each other. Thus, contrary to the scaling delocalisation model, renormalisation occurs only when ω c τ =1. The Hall resistivity at the transition point is close to its classical value, as predicted by the Chern-Simons-Landau-Ginzburg theory of the quantum Hall effect.

Optical and electrical properties of silicon nanopillars

The electrical and optical properties of silicon nanopillars (Si NPs) are studied. Electron-beam lithography and reactive ion etching are used for the formation of ordered Si-NP arrays. The Si NPs with a diameter from 60 to 340 nm and a height from 218 to 685 nm are formed. The Si NPs are coated with a TiONx layer with a thickness of 8 nm for chemical and electrical passivation of the surface. Scanning electron microscopy and atomic-force microscopy are used to characterize the obtained structures. The Si-NP arrays acquire various colors when exposed to “bright-field” illumination. The spectra of reflection from the Si-NP arrays in the wavelength range 500–1150 nm are obtained.

Silicon-on-insulator nanotransistors: Prospects and problems of fabrication

Basic problems encountered in the fabrication of nanosized transistors are considered. Field-effect transistors, which are based on silicon-on-insulator structures, have various gate configurations, and are an alternative to conventional metal-oxide-semiconductor (MOS) transistors, are tested. It is shown that the structures of multichannel transistors, which are based on uniformly doped layers of silicon-on-insulator and have a three-dimensional gate, are the most promising: these structures make it possible to solve the problems of both the short-channel effect for a conventional MOS transistor and the low current density in nanotransistors with a single channel.

Micron-image transfer system with brightness amplifier in gold-vapor laser

A gas-discharge gold-vapor laser on self-terminating transitions with operating wavelength λ=312.2 nm has been used to develop a highly efficient system for image transfer. An optical scheme and all its parameters have been chosen optimal for image quality. It has been found both theoretically and experimentally that the best results on micron-structure image transfer are obtained with 2–5-times image reduction. Various types of masks have been used. A 1-µm structure has been resolved due to the choice of optimal exposure time of 10 ms under a period of pulse repetition (0.6 – 0.8) ms; in this case, the minimal fringe dimension was ≈2 µm with an image dimension of 2 mm for a laser tube 1.8 cm in diameter.