Gallium oxide (Ga2O3) is one of the most promising wide-bandgap semiconductors for the development of next-generation electronic and optoelectronic devices. Doping of Ga2O3 with various impurities via ion implantation is widely employed in the fabrication of such devices. This requires a comprehensive investigation of the influence of implantation conditions on defect formation, the behavior of defects and impurities before and after annealing, and the resulting properties of the ion-doped layers. Boron, as a dopant, is of particular interest due to its minimal atomic mass and smallest ionic radius among the elements isovalent with gallium. In this study, the cathodoluminescence spectra of β-Ga2O3Fe single crystals with a surface orientation of (2¯01), subjected to boron ion implantation (both as-implanted and after subsequent annealing), have been studied. Known luminescence lines associated with native defects have been identified, along with certain features specific to boron, such as a pronounced separation of the green emission line and a significant reduction of the UV line at higher irradiation fluences. The discussion of these observations is conducted in the context of previously established data.

Gallium oxide (Ga2O3) is one of the most promising wide-bandgap semiconductors for the development of next-generation electronic and optoelectronic devices. Doping of Ga(2)O(3)with various impurities via ion implantation is widely employed in the fabrication of such devices. This requires a comprehensive investigation of the influence of implantation conditions on defect formation, the behavior of defects and impurities before and after annealing, and the resulting properties of the ion-doped layers. Boron, as a dopant, is of particular interest due to its minimal atomic mass and smallest ionic radius among the elements isovalent with gallium. In this study, the cathodoluminescence spectra of beta-Ga2O3Fe single crystals with a surface orientation of (201), subjected to boron ion implantation (both as-implanted and after subsequent annealing), have been studied. Known luminescence lines associated with native defects have been identified, along with certain features specific to boron, such as a pronounced separation of the green emission line and a significant reduction of the UV line at higher irradiation fluences. The discussion of these observations is conducted in the context of previously established data.

In this work, we studied the formation of silver nanoparticles on silicon substrates by irradiating thin silver films with Ar+1000 cluster ions with an energy of 10 keV. The topography of the film surface was studied using scanning electron microscopy. The dependence of the particle size and their surface density on the ion fluence was described, which opens a way for controlling the geometric parameters of the particles. Particle formation was considered as a result of two competing processes: sputtering and surface migration of the film atoms. Irradiation with cluster ions at oblique incidence leaded to formation of the particles of elongated shape, with the particle height being comparable to the initial film thickness. Applicability of the particles to surface enhanced Raman spectroscopy was characterized using the dye rhodamine 6 G.

The paper presents experimental data on the kinetics of charging and cathodoluminescence (CL) of single-crystal sapphire under electron irradiation. We give a new explanation for the previously found effect of the delay in surface potential development during charging of single-crystal sapphire by an electron beam, and simultaneous increasing of CL intensity. Such a delay can be explained by a gradual accumulation of negative charge in the sapphire volume, which volume is larger than the initial electron-solid interaction region, together with high secondary electron emission. Such charge spreading leads to an increase in the CL intensity throughout the surface potential delay. A hypothesis is suggested that the delay time is determined by the initial number of electron traps. Subsequently, when sufficient charge is accumulated, a retarding electric field arises inside the sample, leading to a decrease of the region of negative charge localization and almost complete neutralization of the positive charge.

A model for the evolution of surface nanorelief under irradiation with gas cluster ions is proposed. The model is based on consideration of individual collisions of clusters with a surface. The amount of substance sputtered from the collision area and the e ciency of its redeposition onto other surface elements are determined. The performance of the model is shown when compared with experimental data. The stages of smoothing of a harmonic relief are studied. A new measure of the e ectiveness of surface smoothing is proposed.

The effect of the target temperature on sputtering by gas cluster ions was investigated using molecular dynamics simulation. The temperature of <111> copper target was set in range from 300 K to 1100 K, and bombarding 10 keV argon clusters had the size from 50 to 500 atoms. Sputter yield was found to increase with the temperature. The increase depended on the cluster size, and its value was much higher than it had been considered previously for nonlinear sputtering. Differential characteristics of the process, such as angular, energy, and time distributions of the sputtered atoms, as well as their initial positions, were obtained to promote understanding of the mechanisms involved. The dynamics of the collision crater size and its shape were described. The concept of temperature inside the collision area was used to explain the results.

Additive manufacturing (AM) is a modern developing group of technologies based not on material removal, but on the layer-by-layer growth and synthesis of an object according to a CAD (computer-aided design) model. The main disadvantages of objects manufactured by AM technologies are a high degree of porosity and surface roughness. This study examines the possibility of modifying the surface of additive materials Ti ^6 Al ^4 V and AlSi ^10 Mg by irradiation with Ar ^+ ions with energies ranging from 2 to 9 keV. Using SEM, the surface topography was obtained before and after irradiation and mechanical polishing. A reduction in surface porosity and roughness was demonstrated, as well as the influence of beam energy on the final surface topography.

Nitinol is an alloy of roughly equiatomic nickel and titanium, having shape memory and widely used in many applications, such as aerospace, automotive, biomedical and others. One of techniques for its treatment is plasma or ion beam irradiation. In the work we investigated surface composition and topography of the alloy formed by ion and cluster ion bombardment. A strong enrichment of the surface with nickel is detected, which does not agree with contemporary ideas about preferential sputtering. The results were compared with other known results in the area, and the processes occurring under ion irradiation of compound materials were discussed. The role of ambient oxygen in the steady state surface composition establishing is described.

Kinetics of single crystal MgO electrization showed a delay in the surface potential establishment. A number of processes taking place in the surface electrization and, in their turn, influenced by it, are discussed: secondary electron emission, accumulated charge distribution and spreading in the sample, modification of defects in the sample by the electron beam. The evolution of cathodoluminescence spectra was recorded during the irradiation process, showing both increases and decreases in intensity. A synergetic effect was suggested to explain the subthreshold generation of defects by the electron beam.

A model for the evolution of surface nanorelief under irradiation with gas cluster ions is proposed. The model is based on the consideration of individual cluster collisions with a surface. The amount of material sputtered from the collision area and the efficiency of its redeposition on other surface elements are determined. The model’s performance is demonstrated through comparison with experimental data. The stages of smoothing the model harmonic relief are investigated. A new measure of surface smoothing efficiency is proposed.

Topography and composition of the surface of nickel-based alloys under irradiation with Ar2500+ cluster ions with the energy of 20 keV, and atomic Ar+ ions with the energy of 3 keV have been studied. It has been experimentally found that the surface of the alloys is depleted by a component with a lower binding energy. It is shown that the change in the surface concentrations of the alloy components upon irradiation with cluster ions is an order of magnitude greater than upon sputtering with atomic ions. The degree of change in the surface composition is determined by the ratio of the sputtering yields of the alloy components. Keywords: gas cluster ions, ion sputtering, XPS, preferential sputtering, surface topography.

In the study, surface binding energies for pure Ni and Pd metals were calculated using density functional theory. The values obtained were 5.32 and 4.65 eV, respectively, which represents good accuracy for ab initio calculations. The work also included calculations of surface binding energy for different configurations of NiPd alloys with nickel and palladium concentrations of 66, 50, and 33 % . Calculations were performed for each type of lattice for both Ni and Pd surface binding energies. Several types of lattices were simulated, and it was found that the average surface binding energies for Ni and Pd are: 5.02 and 4.36 eV, respectively in the alloy with a Ni concentration of 50 % ; 4.89 and 4.22 eV, respectively in the alloy with a Ni concentration of 66 % ; 5.12 and 4.40 eV, respectively in the alloy with a Ni concentration of 33 % .

In this work, we studied the effect of 350 keV proton irradiation with two different fluences of 1013 cm-2 and 1015 cm-2 on the cathodoluminescence (CL) spectrum of GaN. Three lines were observed in the CL spectra of virgin and proton pre-irradiated samples -band edge line (3.4 eV), blue line (2.8 eV) and yellow line (2.15 eV). A strong decrease in the CL intensity for samples pre-irradiated by protons, especially at high proton fluence of 1015 cm- 2, is shown. The evolution of the cathodoluminescence spectra during electron irradiation demonstrates a further decrease in all line intensities. It was shown that virgin and proton pre-irradiated GaN samples were not charged under electron irradiation. The cathodoluminescence signal drop can be caused by a decrease in the concentration of initial luminescence centers associated with intrinsic and impurity defects due to their trans-formation under proton bombardment and electron-stimulated diffusion implanted H+ ions.

Cluster ion beams are a perspective tool for surface structuring and analysis due to nonlinear processes occurring under cluster-surface interaction. We focused our attention on the experimental and molecular dynamics simulation study of gold sputtering with bismuth cluster ions. In addition, a copper target was also investigated where etched craters were examined. Non-additive behavior of sputter yields is discussed in terms of Sigmund and Claussen thermal spike models. These simulations have allowed us to compare penetration of atomic and cluster bismuth into the targets as well as studying the differential characteristics of sputtering.

In the present work, we studied structure, surface morphology, and ultrasonic response of thin film Lithium Niobium Oxide (LNO) transducers deposited on Inconel bolts, stainless steel and silicon substrates by radio frequency magnetron sputtering. The deposited transducer material was a mixture of LiNbO3/LiNb3O8 phases, having a well-developed columnar structure. Further, the in-situ high-temperature ultrasonic response was studied in the temperature range of 18-800 degrees C in ambient air during short-term annealing. It was observed that long-term annealing (at 700 degrees C for 160 h and 800 degrees C for 40 h) deteriorated the ultrasonic response, owing to the irreversible change from the initial columnar structure to the porous granular structure. Dielectric and piezo-electric properties of the thin film LNO transducers were also studied. The thin film LNO ultrasonic transducers have potential applications in bolts and screws up to 700 degrees C.

Total currents of positive and negative particles arising under bombardment of metal surfaces with argon gas cluster ions were measured for the energy range 2–15 keV. Supposing that the negative current was defined by secondary electrons, and the positive current is the flow of the reflected argon ions, the possible mechanisms of electron emission and charge transfer are discussed. The discussion is supported by molecular dynamics simulations of cluster-surface collisions.

X-ray photoelectron spectroscopy was used to study the evolution of NiTi alloy surface composition under bombardment with atomic and cluster argon ions. A strong enrichment of the surface with nickel was found for both atomic and cluster ions, which is inconsistent with contemporary understanding of preferential sputtering. Possible reasons for this result are discussed.

To establish the effect of subthreshold defect formation on the charge accumulation in quartz glasses, a comprehensive study of the process of their electrization by electron beams was carried out. Earlier it was shown that the process of radiative electrization of quartz glasses consists of two stages. The short-term stage of charging can be explained by the accumulation of charge on the initial trap centers, and the long-term component can be caused by the generation of deep trap centers capable of capturing electrons. In the studied quartz samples, the trapping centers can be three-coordinated silicon atoms (E'-centers). The presence of two stages of the charging process is confirmed by two different methods for determining the surface potential. Despite the increase in the surface potential during irradiation and the resulting decrease in the energy of the incident electrons, an increase in the intensity of the cathodoluminescent signal is observed. Such an increase in intensity can be caused by an increase in the number of luminescent defects in quartz, a two-coordinated silicon atom or a non-bridging oxygen atom, as well as by charge accumulation at competing nonradiative trap centers.

The dependence of the current of secondary particles on the thickness of dielectric films is studied to determine the effect of the surface potential of dielectric samples on the yield of positive ions during ion irradiation. It is shown that the yield of positive secondary particles increases significantly with increasing thickness if the film charging potential does not exceed the breakdown value depending on the electrical strength of the film. One indirect confirmation of film charging in these experiments is the time dependence of the current from the sample holder. The hardware effect caused by the emission of secondary electrons from a hemispherical collector is experimentally studied. Possible features of the phenomena are discussed.

Temperature dependences of the copper sputtering yield by argon cluster ions in the temperature range from 300 to 1100 K (0.8 of the melting point) have been studied by numerical simulations using molecular dynamics method. The sizes of argon clusters with a fixed energy of 10 keV were from 50 to 500 atoms. It has been found that the temperature dependence of the sputtering yield becomes more pronounced with increasing cluster size, i.e., with decreasing specific energy of its atoms. The results are compared with the thermal spike model.