Vol 48, No 2 (2019)
- Year: 2019
- Articles: 9
- URL: https://journals.rcsi.science/1063-7397/issue/view/11724
Article
Influence of Pulsed Laser Deposition Modes on Properties of Nanocrystalline LiNbO3 Films
Abstract
The influence of the duration of pulsed laser deposition on the properties of lithium niobate films is elucidated. An increase in the deposition time from 90 to 360 min is found to vary the LiNbO3 film thickness from (47.5 ± 3.8) to (197.9 ± 15.8) nm as the roughness of the film surface increases from (3.57 ± 0.17) to (32.7 ± 2.32) nm and the grain size increases from (235 ± 22) to (346 ± 33) nm, respectively. The influence of PLD duration on phase composition, electrophysical, and optical properties of nanocrystalline LiNbO3 films are also explored. The increase in the film thickness from (110.1 ± 8.8) to (143.8 ± 7.0) nm is established to cause the hysteresis in the polarization as a function of field strength, which allows us to refer these films as ferroelectric films and use them in state-of-the-art electron elements of acousto-optics and piezotechnics.
Nanoscaled Profiling of Silicon Surface via Local Anodic Oxidation
Abstract
The nanoscaled profiling of a silicon 5 (111) n-type substrate surface is studied by the local anodic oxidation (LAO). Varying the voltage pulse amplitude from 5 to 12.5 V and the humidity from 30 ± 1 to 70 ± 1% during the LAO is a promising way to form oxide structures with heights from 0.5 ± 0.3 to 2.1 ± 0.1 nm and profiled structures with depths from 0.4 ± 0.3 to 1.5 ± 0.2 nm on the substrate. The results can be applied to the development of technological processes of the element base of silicon-based nanoelectronics using the probe nanotechnologies.
Studying the Regimes of Silicon Surface Profiling by Focused Ion Beams
Abstract
The regimes of submicron and nanosized profiling of the KDB-10 Si(100) wafer surface by the focused ion beam (FIB) technique are experimentally investigated. It is established that with an increase in the ion beam current from 1 to 300 pA, the diameter and depth of nanostructures increases from 45 to 380 nm and from 82 to 494 nm, respectively. The best resolution determined by the minimum distance between etched lines is found to be 10 nm. It is demonstrated that with a decrease in the ion beam current from 7 nA to 1 pA and in the dwell time from 100 to 0.2 µs, the deviation of etched structure walls from the vertical decreases to 30°. The results obtained can be used to develop technologies for fabricating nanoelectronic and microsystems engineering elements by the FIB technique.
Formation of Dielectric Nanolayers of Aluminum and Silicon Oxides on AIIIBV Semiconductors
Abstract
The results of investigations of the synthesis of silicon and aluminum oxide nanolayers on the GaAs, InAs, and InSb binary semiconductor surface by molecular layering (atomic layer deposition) are generalized. The conditions for the layer-by-layer growth of the surface nanostructures are established and some of their dielectric characteristics are estimated.
Effect of the Fermi Surface Anisotropy on the Electrical Conductivity of a Thin Inhomogeneous Metal Wire
Abstract
The high-frequency electrical conductivity of a thin inhomogeneous metal wire with a dielectric core is calculated using the kinetic approach. The Fermi surface of a metal is assumed to be an ellipsoid of revolution with the rotational axis coinciding with the wire axis. In the investigated case of isotropic electron scattering, the volume relaxation time does not depend on either the energy or the direction of electron scattering. No limitations are imposed on the ratio between the conduction’s electron free path and wire radius. The dependences of the absolute value and argument of the dimensionless conductivity on the dimensionless transverse effective mass, dimensionless wire radius, dimensionless electric field frequency, and ratio between the wire and dielectric core radii are analyzed.
Features of the Kinetics of Bulk and Heterogeneous Processes in CHF3 + Ar and C4F8 + Ar Plasma Mixtures
Abstract
We carry out a comparative study of the kinetics of plasma-chemical processes and plasma composition in CHF3 + Ar and C4F8 + Ar mixtures under the conditions of a high-frequency (13.56 MHz) induction discharge. Using diagnostic methods and plasma modeling, the general features and differences of the plasma’s electrophysical parameters in the studied systems are established together with the key bulk processes that determine the stationary concentrations of neutral particles. Тhe CHF3 + Ar system in the range 0–75% Ar is shown to be characterized by lower values of the flux densities of the fluorine atoms and polymer of the forming radicals. Model analysis of the kinetics of the heterogeneous processes (etching, polymerization, degradation of the polymer film) confirmed the advantage of the C4F8 + Ar system of silicon etching anisotropy and etching selectivity compared to the SiO2/Si system.
Studying the Thermodynamic Properties of Composite Magnetic Material Based on Anodic Alumina
Abstract
In this paper we study the thermodynamic, morphological, structural, and chemical properties of a composite material consisting of nickel nanowires (NWs) electrochemically deposited in the pores of the membrane of porous anodic aluminum oxide (PAA) by methods of differential thermal analysis (DTA), scanning electron microscopy (SEM), X-ray diffraction analysis (XRD), and dispersive X-ray spectroscopy (EDX).
Fabrication and Electrical Characteristics of Asymmetric Rings Made of HTS YBCO Films Obtained by Pulsed Laser Deposition
Abstract
HTS YBCO films 200–400 nm thick are fabricated by pulsed laser deposition, both without filtration and in the regimes of velocity filtration of particles of an ablation plume. Using AFM and SEM, it is established that the size of large particles in the plane of films during deposition without filtration ranges from 60 to 1000 nm. After filtration, the maximum particle size in the film plane is less than 500 nm. Two types of irregularities are found on the surface after deposition: irregularities obtained from rounded particles and irregularities from faceted crystals. Using the methods of electron lithography and etching with argon ions through a mask, micro- and nanostructures are fabricated from HTS films. A correlation has been found between the characteristic dimensions of the irregularities on the surface of the films and the available lateral resolution of the microstructures obtained. For structures from HTS films that are asymmetric rings with a characteristic line width of 800 nm, the temperature dependences of the superconducting transition are determined and their asymmetric I–V characteristics are observed.
Effect of the Built-in Surface Potential on the I–V Characteristics of Silicon MIS Structures
Abstract
The regularities of the modification of I–V characteristics of MIS structures via forming built-in surface potentials induced during the fabrication of an atomically pure silicon crystal surface using microwave plasma micromachining in different chemically active gaseous media are investigated. The effect of surface potentials on the slope of the I–V characteristics of the MIS devices and the value of their asymmetry at the reversal of the gate polarity are established. The increase in the slope of the I–V characteristics is attributed to the weakening of the diffuse scattering of electrons during the formation of negatively charged surface trap states at the interface and an increase in their mobility in the space charge layer at the semiconductor surface.