No 10 (2024)

The structure of the side surfaces of the bulk Zr₆₂Cu₂₂Fe₆Al₁₀ amorphous sample after compressive deformation at room temperature was studied using X-ray diffraction and scanning electron microscopy methods. After preparation, the samples of the amorphous alloy had a square cross-section of 5 × 5 mm and a length of 40 mm. Examining the side surface allows one to avoid influencing the surface structure of the tool used for deformation. Plastic deformation of amorphous alloys occurs through the formation and propagation of shear bands. During compressive deformation at room temperature, a system of steps was formed on the end surfaces of the sample, caused by shear bands coming to the surface. Steps on surfaces have different sizes (thickness and height). It has been established that the structure of large steps is complex: they consist of elementary steps 15–30 nm thick. The local deformation was estimated based on the size of the steps. The formation of a small number of nanocrystals during deformation was discovered. The nanocrystals are approximately 10 nm in size. The results obtained open a new direction for research into the structure of deformed amorphous alloys and nanocrystallization processes under the influence of deformation.

The properties of a metal contact with a p-GaAs layer ~8 nm thick induced by low-energy Ar⁺ ions on an n-GaAs wafer as a result of the conduction tipe type conversion have been studied. The metal was deposited according to the standard technology on the surface of the semiconductor p-GaAs with a natural oxide layer, partially restored when the sample was transferred to a deposition setup. To prevent metallization of the nanolayer, the contact was not annealed. Therefore, a Schottky barrier emerged at the interface and a residual oxide layer retained. However, current-voltage characteristics showed that the formed contact is predominantly ohmic. It has been found that a high concentration of ion-induced defects radically reduces the width of the Schottky barrier and ensures the tunneling of holes and electrons of the semiconductor valence band through the barrier in the forward and reverse directions, respectively. It is shown that ion bombardment of the p-GaAs semiconductor surface makes it possible to obtain an ohmic contact with any metal without annealing. It is concluded that the ion-stimulated modification of the semiconductor and the exclusion of annealing make it possible to obtain a tunnel ohmic contact with an extremely thin p-GaAs nanolayer coated with a residual layer of natural oxide.

The experimental results of studying the influence of ion etching of cation-substituted iron-garnets single-crystal films on their structural, magnetic, optical and magneto-optical properties are presented in article. It has been shown, that the ionic etching of the surface of single-crystallin garnets significantly decrease the surface roughness. An analysis of the domain structure, ferromagnetic resonance spectra, and magneto-optical hysteresis loops in a bismuth-substituted iron-garnet epitaxial film during layer-by-layer ion etching showed the presence of three different layers, the state of which changes relative to the compensation point, and the interlayer interfaces correspond to the transition through the compensation point. It has been shown, that the position of interlayer interfaces can be changed by the sample temperature changing. The investigation of optical and magneto-optical characteristics showed that in single-crystallin (epitaxial) films of iron-garnets the ion etching does not impair optical transmission and does not destroy the garnet structure up to a thickness of tens of nanometers (the Faraday effect is retained).

An overview of the use of electron spectroscopy for the study of the physico-chemical properties of solids is carried out. It is noted that the main source of information about the electronic states of atoms is the energy distribution of electrons excited by ions, X-ray quanta, and laser beams. The paper briefly discusses the problems that exist in registering the spectra of secondary electrons obtained by exciting the surface of samples with electrons of medium (1–20 keV) energies, and ways to solve these problems in order to increase the information content and accuracy of research results. A method for recording secondary electron spectra in an integral form using an Auger spectrometer is proposed, which allows to increase the energy resolution of the method. The possibilities of the method are demonstrated by the example of experimental studies of zirconium carbide and steel X17AG18.

Methods of modifying surface and near-surface layers of materials and coatings by ion beams can be applied in many fields of science and technology. To practically implement the technologies for the targeted improvement of the performance properties of parts and products for various purposes, it is of great interest to develop the methods of deep ion doping of near-surface layers of semiconductor materials, as well as metals and alloys due to the enhancement of radiation-stimulated diffusion under conditions when the irradiated sample’s deep layers are not subjected to significant temperature impact. This work studies the features and regularities of the implementing the synergy of high-intensity titanium ion implantation at current densities of several hundred milliamps per square centimeter with simultaneous energy impact of a submillisecond ion beam with a power density reaching several tens of kilowatts per square centimeter on the surface. This work is the first to show that the synergy of high-intensity ion implantation and the energy impact of a high-power density ion beam, taking the titanium implantation into silicon as an example, provides the possibility of increasing the ion doping depth from fractions of a micron to 6 μm by increasing the irradiation time from 0.5 to 60 min.

Electron exchange during grazing scattering of hydrogen ions on thin metal films is considered. The main characteristic being studied is the yield fraction, i.e. the probability of the formation of a certain charge state of a scattered particle (in the case under consideration, H^–) as a function of the velocity component parallel to the surface of the sample. Based on an analysis of the electron distribution in the space of wave vectors, using the generally accepted model of displacement of Fermi spheres, it was shown that the dependence of the probability of the formation of a negative hydrogen ion on the parallel velocity component should decrease monotonically.

The influence of plastic deformation on the formation of nanocrystals in the Al₈₇Ni₆Nd₇ amorphous alloy was studied using X-ray diffraction analysis. It has been shown that deformation accelerates the crystallization of the amorphous phase and can lead to the formation of smaller nanocrystals compared to heat treatment. The size of nanocrystals and their number depend on the treatment conditions of the amorphous phase: when preliminary deformation is used, the size of nanocrystals formed during annealing is smaller than in an undeformed sample. In samples subjected to preliminary deformation by rolling, a gradient structure is formed: the proportion of nanocrystals decreases with distance from the surface into the depth of the sample. The size of nanocrystals changes slightly with changing distance from the sample surface. The results show that preliminary plastic deformation can be an effective method to obtain a nanocrystalline structure with different fraction and sizes of nanocrystals in the amorphous phase. This is important for the creation of highly functional materials with outstanding physicochemical properties. The results obtained significantly expand the existing understanding of the mechanisms of formation of nanocrystals in the amorphous phase under external influences.

Organic-inorganic hybrid perovskite materials based on metal-organic structures are attracting much attention, as they are characterized by rather high photocurrent conversion together with comparative simple production procedure. A model analysis of the possibility to experimentally detect and characterize a lead halide layer formed at the internal interface during degradation of a hybrid perovskite photovoltaic film using in situ neutron reflectometry, is presented. From a comparison of the calculated specular reflection curves, the relationships between the parameters of the system components are identified, at which, despite the generally weak changes in the curves, still it is possible to trace the evolution of this layer.