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In this paper, the irradiation of porous silicon with Ar $${}^{+}$$ ions with the energies of 100 and 200 keV and fluences from $$10^{12}$$ cm $${}^{-2}$$ up to $$3\times 10^{13}$$ cm $${}^{-2}$$ has been performed and studied. The effect of ion irradiation at different fluences and energies of incident particles on the photoluminescence spectrum of porous silicon has been analyzed. It has been shown that ion irradiation leads to a shift of the photoluminescence maximum, which grows with increasing energy. An increase in the fluence reduces the photoluminescence intensity, but, at the same time, has no effect on the magnitude of the maximum shift. The main mechanisms of the photoluminescence in porous silicon are also discussed.

Silicon carbide was irradiated with aluminum ions at an energy of 190 keV with fluences of $$2\times 10^{13}{-}5\times 10^{14}$$ ion/cm $${}^{2}$$ . The temperature of the target during irradiation was 300–500 $${}^{\circ}$$ C or it was kept at room temperature. It is shown that the presence of nitrogen in the structure of silicon carbide erodes the edge of the interband absorption. After irradiation at room temperature, the structure is disordered to form Si–Si and C–C compounds, as well as 3C–SiC. According to the absorption spectra, when the target temperature is increased during irradiation to 500 $${}^{\circ}$$ C, the structure of silicon carbide recrystallizes up to the initial state.

The composition of Ni x Pd y (x, y = 1, 5) and NiMoRe alloys irradiated by 3 and 4 keV Ar + ions along the normal to the sample surface was investigated in situ by low energy ion scattering spectroscopy (LEIS). The analysis was performed using a 5 keV Ne + ion beam. It was found that the composition of the topmost layer of bombarded Ni x Pd y alloys nearly corresponds to the alloy stoichiometry. In the case of irradiation of the NiMoRe alloy, a surface enrichment with the heavier components (Mo and Re) was found. The thermally activated Gibbsian segregation in NiPd and NiPd 5 alloys was also studied using LEIS.

Gas cluster ion beam is known as a tool for surface smoothing; at the same time, surface relief formation under oblique beam incidence was reported. We suggested using samples with pre-formed surface pattern to study its evolution caused by ion irradiation and applied this approach to reveal the mechanisms responsible for nanorelief developing under off-normal cluster ion incidence. The role of key processes, which are ballistic diffusion and sputtering depending on the local incidence angle and surface curvature, is discussed. The irradiation conditions as well as the initial patters found to influence on the resulting surface shape.

4H-SiC was irradiated with Al+ions at an energy of 190 keV. The depth profiles of implanted aluminum were obtained using the secondary ion mass spectrometry method; a comparison was made with profiles calculated in the SRIM program. Using Rutherford backscattering in channeling mode, we studied the amorphization of the crystal structure after ion implantation in the target at room temperature and 400° C. The fluence of 1015 cm−2 was shown to completely disorder the crystal structure under irradiation of a room temperature target. It was found that after ion irradiation of a target heated to 400° C, the penetration depth of the embedded impurity increases. An increase in the target temperature during irradiation leads to the recombination of a significant number of simple defects and the restoration of the crystal structure. The topography of the samples before and after ion irradiation was compared.

Experimental depth distributions of the concentration of implanted xenon ions depending on their charge state and irradiation energy are presented. Xenon ions in charge states q = 1–20 and energies in the range from 50 to 400 keV are incorporated into single-crystal silicon. Irradiation is performed in the direction not coinciding with the crystallographic axes of the crystal to avoid the channeling effect. The ion fluence varies in the range of 5 × (1014–1015) ion/cm2. The irradiation by singly charged ions and investigation of the samples by Rutherford backscattering spectroscopy is performed using an HVEE acceleration complex at Moscow State University. Multiply charged ions are implanted using a FAMA acceleration complex at the Vinća Institute of Nuclear Sciences. The depth distribution profiles of the incorporated ions are found using Rutherford backscattering spectroscopy. Experimental results are correlated with computer calculations. It is shown that the average projective path of multiply charged ions in most cases is shorter when compared with the average projected path of singly charged ions and the results of computer modeling.

In this paper, we study time-of-flight (TOF) mass-spectra of the Ar cluster beams obtained by nozzles with different diameters, at different source pressures, and ionizing electron energies. The TOF mass-spectra are measured at minimal electron energy, since there is a strong influence on the mass-spectra by the multiple ionization of the clusters. The cluster size derived from TOF mass-spectra is considered as a function of the condensation parameter Γ*. Attenuation of the cluster current due to collisions with residual gas is also studied. An estimation of the relative cluster size by the current attenuation is proposed.

A custom-built gas cluster ion source with an energy up to 20 keV is constructed. Ar, CO2, N2, and O2 are used as the working gases. The clusters are formed by metal conical nozzles with critical diameters of 65−135 um and a cone angle of 14°. To facilitate evacuation of the chambers we use the pulse mode of nozzle feeding. This allows an increase in the gas pressure in the stagnation zone (inlet pressure) up to 15 bar. The current of the clusters with an energy of 20 keV is 20 µA; the maximal current density is 3 µA/cm2. The mass spectra of the argon clusters formed at different pressures and electron ionization energy are studied by time-of-flight spectroscopy. The inlet pressure dependence of the mean cluster size is considered as a function of the condensation parameter Г*. An argon cluster beam is used to smooth the surface of the titanium coating and pressed silicon nanopowder. The roughness of the Ti coating surface decreases from 3.7 to 0.8 nm; the removal of microparticles from the surface is also observed. In the case of the surface of Si, besides the smoothing effect the formation of 100 nm craters is observed.

This paper proposes the use of surfaces with a preformed ordered nanotopography to study the mechanisms of the evolution of surface topography under ion beam irradiation. The proposed approach is used for silicon surface bombardment with an oblique beam of accelerated cluster ions. Samples with an ordered topography were formed using electron lithography. The surface was studied using the SEM and AFM techniques. It is shown that the resulting topography is formed as a result of the competition between processes of sputtering and redistribution of atoms. The effectiveness of these processes is determined by the local incidence angles of the ions and the surface curvature. The possibility of obtaining an asymmetric surface profile with the specified parameters is shown by selecting the incidence angle of the ion beam, the irradiation dose, and the initial surface topography.

Effects of He ion irradiation on the structural properties of multi-walled carbon nanotubes (MWCNT) are presented in this study. We carry out MWCNT ion irradiation gradually increasing the fluence. As grown MWCNTs possess a relatively large diameter (∼80 nm) and a significantly defective structure of the external walls. This paper shows how ion irradiation affects MWNTs Raman spectra. Quantitative analysis of the deconvoluted spectral components, together with the XPS and SEM data, help to suggest changes in the MWNTs crystal lattice.

Electrochemical etching of Si is a promising method of fabricating multilayer photonic structures with hundreds of layers. Nevertheless, the natural cleavage of the porous silicon structure has roughness and then high optical scattering that embarrasses the usage of porous silicon in optical devices. In this study, gas cluster ion beam irradiation was suggested as a polishing technique. The bombardment results in surface smoothing and consequent enhancement of light reflection without significant difference in sputtering rate of layers with different porosity. Increasing irradiation dose results in different behavior of porous layers: densification of low-porosity structures and nano-rods formation in high-porosity layers.

The effect of noble gas cluster species on the cluster interaction with solid surfaces was investigated. Processes of Ar, Kr and Xe clusters interaction with Cu and Mo surfaces were studied using molecular dynamics simulations. It is shown that lighter cluster front atoms undergo more backscattering from surface atoms, causing more intense multiple collisions between cluster atoms. This affects cluster penetration, energy exchange between the cluster and surface atoms, and cluster thermalization. The influence of energy per cluster atom on these effects is discussed. The effect of noble gas cluster species on the cluster interaction with solid surfaces was investigated. Processes of Ar, Kr and Xe clusters interaction with Cu and Mo surfaces were studied using molecular dynamics simulations. It is shown that lighter cluster front atoms undergo more backscattering from surface atoms, causing more intense multiple collisions between cluster atoms. This affects cluster penetration, energy exchange between the cluster and surface atoms, and cluster thermalization. The influence of energy per cluster atom on these effects is discussed.

The results of ab initio studies of the atomic and charge structure of small clusters and cluster ions formed by 13 and 19 argon atoms are reported. It was found that the icosahedral atomic structure is energetically the most favorable for such clusters. The calculations demonstrate that when a single electron is removed from a cluster, the excess positive charge is distributed primarily over the surface of the formed cluster ion.

Volume: 406 Host publication title: Nuclear Instruments and Methods in Physics Research Section B: Beam Interactions with Materials and Atoms The results of molecular dynamics simulations of the bombardment of the Cu (100) and Mo (100) single-crystals by 10 keV Ar cluster ions of different sizes are presented in this paper. Spatial distributions of sputtered material were calculated. The anisotropy of the angular distributions of sputtered atoms was revealed. It was found that the character of the anisotropy is different for Cu and Mo targets. The reasons leading to this anisotropy are discussed according to the dependences of the angular distributions on the cluster size and on the target material.

As silicon is an important element in semiconductor devices, the process of defect formation under ion irradiation in it is studied well enough. Modern electronic components are made on silicon lattices (films) that are 100–300 nm thick (Chernysh et al., 1980; Shemukhin et al., 2012; Ieshkin et al., 2015). However, there are still features to be observed in the process of defect formation in silicon. In our work we investigate the effect of fluence and target temperature on the defect formation in films and bulk silicon samples. To investigate defect formation in the silicon films and bulk silicon samples we present experimental data on Si+ implantation with an energy of 200 keV, fluences range from 5 * 1014 to 5 * 1015 ion/cm2 for a fixed flux 1 μA/cm2 and the substrate temperatures from 150 to 350 K The sample crystallinity was investigated by using the Rutherford backscattering technique (RBS) in channeling and random modes. It is shown that in contrast to bulk silicon for which amorphization is observed at 5 × 1016 ion/cm2, the silicon films on sapphire amorphize at lower critical fluences (1015 ion/cm2). So the amorphization critical fluences depend on the target temperature. In addition it is shown that under similar implantation parameters, the disordering of silicon films under the action of the ion beam is stronger than the bulk silicon.

Iron ions with energies of 90 and 250 keV and a dose of 1016 cm–2 are implanted into a silicon single crystal with the (110) orientation. The method of Rutherford backscattering in combination with channeling is used to study the distribution profiles of the introduced impurity and also the profiles of the distribution of radiation-induced defects in the crystal lattice. Experimental data are compared with the results of simulation performed using the TRIM software package. It is shown that, at an energy of 4.6 keV/nucleon, the average projected ranges coincide; however, at an energy of 1.6 keV/nucleon, the difference amounts to 35%. In addition, it is shown that the calculation incorrectly takes into account the dose dependence at energies of 1.6–4.6 keV/nucleon.

We present experimental studies and computer simulations of the energy distributions of the particles sputtered from copper and molybdenum with gas cluster ions. Both experimental and simulated distributions were found to be narrower than ones known for atomic ion sputtering. It was shown that the distributions of sputtered atoms obtained by molecular dynamics simulations can be well described in frames of the thermal spike theory. For a given cluster energy, its size and the target material properties determine the parameters of the distributions. Including into consideration sequential cluster impacts on the target surface resulted in changes both in energy and angular distributions of sputtered matter and as well in total sputtering yield. Experimentally measured distributions well matched the ones simulated in “sequential” mode.

Polycrystalline NiPd and Ni5Pd alloys were irradiated with argon gas cluster ion beam and atomic ion beam. In situ XPS measurements showed surface enrichment with Ni. For cluster ions, the degree of the enrichment was significantly higher, and the ion current density influenced on it. Under oblique cluster ion beam, ripples developed on the surface, and the elements of the alloy redistributed along the surface according to the ripple pattern. For normal cluster ion beam direction, sputtering rate was determined by a crystalline orientation, which limited the smoothing effect.

The experimental angular distributions of atoms sputtered from polycrystalline W and Cu with 10 keV Ar and Xe cluster ions are presented. RBS was used to analyze a material deposited on a collector. It has been found that the mechanism of sputtering, connected with elastic properties of materials, has a significant influence on the angular distributions of sputtered components. The angular distributions were simulated using molecular dynamics calculations. A new approach taking into account experimental cluster mass distributions in the beam and surface topography was developed. This approach was fruitful for understanding the particular features of the experimental angular distributions of sputtered material.

Defect formation in silicon-on-sapphire films under the action of a gas beam of 30 keV argon cluster ions is studied. Rutherford backscattering in the channeling mode is used to demonstrate the formation of a large number of defects in the volume of a specimen that is irradiated by a cluster ion beam without mass separation. If atomic and light cluster ions are removed from the beam, defect-free etching of the specimen occurs.

Supersonic nozzle is a key component of a gas cluster condensation system. We describe a flow visualization system using glow discharge with annular or plane electrodes. The geometric parameters of a supersonic jet under typical conditions used in a gas cluster ion beam accelerator are investigated. As well numerical simulations were performed. Dependence of inlet and ambient pressures and nozzle throat diameter on the shock bottle dimensions is described for different working gases. Influence of condensation rate on shock bottle axial size is discussed.

The experimental angular distributions of atoms sputtered from polycrystalline W, Cd and Ni based alloys with 10 keV Ar cluster ions are presented. RBS was used to analyze a material deposited on a collector. It has been found that the mechanism of sputtering, connected with elastic properties of materials, has a significant influence on the angular distributions of sputtered components. The effect of non-stoichiometric sputtering at different emission angles has been found for the alloys under cluster ion bombardment. Substantial smoothing of the surface relief was observed for all targets irradiated with cluster ions.

We have studied the influence of bombardment with accelerated gas-cluster ions on the surface topography of silicon carbide and diamond. Atomic-force microscopy shows that exposure to 10-keV gas-cluster ions at a total dose above 1016 cm–2 leads to smoothing of the surface relief. The ion-etching rate and efficiency of the surface relief smoothing as dependent on the thickness of removed layer have been estimated. Raman-spectroscopy data show that surface irradiation with gas-cluster ions does not introduce defects into the crystalline structure of irradiated material.

Angular distributions of atoms sputtered from Cu, Mo and In under 10 keV Ar cluster ion bombardment (normal incidence) have been studied experimentally. RBS was used to analyze material deposited on a Al collector. It has been found that the angular distribution of atoms sputtered from Mo differs drastically from the one previously published for Cu by other authors. A new mechanism of sputtering with cluster ions is suggested to describe the observed angular distributions.

The effect of the parameters (energy, dose) of the irradiation of silicon-on-sapphire (SOS) structures with ions Si+ ions on the quality of the silicon-film crystal structure after solid-phase epitaxial recrystallization and annealing is studied. It is shown that the most efficient mechanism of crystal-structure recovery is recrystallization from the silicon surface layer which is a seed.

Gas cluster formation during gas expansion through a supersonic nozzle with a skimmer is described. The role of the buffer zone between a pulsed valve and a nozzle in the regime of pulsed supply of working gas is shown. Influence of the working gas type on the cluster ion pulse parameters is investigated.

Silicon-on-sapphire (SOS) is one of the most promising silicon-on-insulator (SOI) technologies. SOS structures are widely used in microelectronics, but to meet modern requirements the silicon layer should be 100 nm thick or less. The problem is in amount of damage in the interface layer, which decreases the quality of the produced devices. In order to improve the crystalline structure quality SOS samples with 300 nm silicon layers were implanted with Si + ions with energies in the range from 180 up to 230 keV with fluences in the range from 10 14 up to 5 × 10 15 cm −2 at 0 °C. The crystalline structure of the samples was studied with RBS and the interface layer was studied with SIMS after subsequent annealing. It has been found out that to obtain silicon films with high lattice quality it is necessary to damage the sapphire lattice near the silicon–sapphire interface. Complete destruction of the strongly defected area and subsequent recrystallization depends on the energy of implanted ions and the substrate temperature. No significant mixing in the interface layer was observed with the SIMS.

A gas cluster ion accelerator with energies up to 20 keV is described. Parameters of the main components of the equipment were determined. It was demonstrated that a pulse regime of the accelerator can be realized with a relatively low (500 l/sec) pumping speed of the cluster ion source. Conditions for stable cluster beam generation were found. In pulse mode ion clusters appear in the accelerated beam in the first stages of ion beam evolution. A model describing the behavior of the ion beam in the pulse regime is suggested. To analyze the beam mass composition two systems were constructed: a magnetic mass-separation system and a time-of-flight system. Cluster ions Ar n + with number of atoms/charge n ≥ 500 were detected in the beam by using deflection in a homogeneous magnetic field. Clusters up to 3000 atoms/charge were detected by using time-of-flight measurements.

An experimental setup for medium energy ion scattering spectroscopy allowing materials elemental composition diagnostics has been developed. A target composed of single-crystalline Ge with a smooth surface and structural inhomogeneity several nanometers thick has been prepared for conducting the experiments. Experiments have shown that the depth resolution of the method was 6 A.

The angular distribution of atoms sputtered from Co 5 Sm alloy under 3 keV Ar + and 10 keV Xe + ion bombardment (normal incidence) has been studied experimentally. RBS was used to analyze a material deposited on a collector. The surface composition of Ni x Pd y alloys ( x , y = 1, 3, 5) irradiated by 3 keV Ar + ions was also investigated in situ by Auger electron spectroscopy. Results of these measurements compared with our previous data on component angular distributions sputtered from Ni 5 Pd alloy. Sm segregation was found to effect on component angular distributions sputtered from Co 5 Sm alloy. It has been found by using AES that Pd segregates to the surface in Ni 5 Pd–NiPd 3 alloys, while Ni – in NiPd 5 alloy. A new approach to description of component angular distributions sputtered from Ni x Pd y and Co 5 Sm alloys presented.

It is shown that unlike bulk silicon, for which amorphization is observed at an irradiation dose of 5 × 1016 ion/cm2, thin silicon films on sapphire are amorphized at lower critical doses (1015 ion/cm2). An undamaged surface layer remains when the silicon films are irradiated with Si+ ion beams. Its thickness depends on the current density of the incident beam. Rutherford backscattering studies show that annealing at 950°C improves the crystallinity of the irradiated silicon film. Annealing of the films at 1100°C leads to mixing of the silicon-sapphire interface.

Ion channeling in a system of partially ordered nanotubes is considered. According to the results of numerical analysis, the channeling effect should be clearly observable for protons at energies of several hundred eV.

The angular distribution of atoms sputtered from NixPdy alloys (x, y=1, 5) under 3 and 10 keV Ar+ ion bombardment has been studied experimentally and using computer simulations. A collector technique combined with RBS to analyze the distribution of collected material was used. It was found that the Pd/Ni yield ratio increases with the polar ejection angle θ for all targets excluding NiPd5. This peculiarity of sputtering was explained by a reversion of atomic segregation at high initial concentrations of Pd atoms in the target.

The surface topography of silicon and germanium single crystals formed under 10-keV Ar+ and Ne+ irradiation was studied experimentally. A relief with typical nanometer-scale dimensions is detected using atomic-force microscopy. It is established that the average height of the nanorelief formed depends on the silicon doping levels. It is also shown that the average height is determined by the parameters of ion irradiation.

The angular distribution of atoms sputtered from germanium under 1–20 keV Ar+ ion bombardment (normal incidence) has been studied experimentally and using computer simulations. A collector technique combined with Rutherford backscattering to analyze the distribution of collected material was used. In addition, the surface topography was under control. It was found that the experimental angular distribution of sputtered atoms (E 0=3–10 keV) could be approximated by the function cos n θ with n≈ 1.65. Such a high value of n is connected with the surface scattering of ejected atoms and a noticeable contribution of backscattered ions to the formation of the sputter flux (the mass effect). The target surface was found to be practically flat even at ion fluencies ∼1018 ions/cm2. The results obtained are compared with data from the literature, including our recent data on Si sputtering.

We have used low-temperature (4.2–78 K) photoluminescence to study defect formation processes in Cu(In,Ga)Se2 films when bombarded by protons with energy 380 keV. We have observed formation of luminescence centers with deep levels at ∼410 meV and 470 meV.

Germanium ions of an expanding plasma were implanted in a silicon collector. The plasma was produced by a femtosecond laser pulse with an intensity of ~1015 W cm-2 at the surface of the solid-state target. A technique was proposed for determining the energy characteristics of the ion component of the laser plasma from the density profile of the ions implanted in the substrate.

The angular distribution of atoms sputtered from silicon under 1–10 keV Ar ion bombardment (normal incidence) has been studied experimentally and using computer simulation. It has been found that the angular distribution is overcosine in the whole energy range studied. This is connected with a high contribution of secondary knock-on atoms to the sputter flux (cascade sputtering). The simulated angular distributions are shown to be quite sensitive to the variation of the interatomic potential. The results obtained are compared with data from the literature.

The effect of energy, dosage, and temperature of irradiation of silicon-on-sapphire structures by Si+ ions, as well as parameters of recrystallization annealing, on crystallinity of silicon film is shown. Implantation conditions and recrystallization annealing conditions are determined.

Iron ions with energies of 90 and 250 keV and the irradiation dose of 1016 ions/cm2 and xenon ions with energies of 100 keV and dose 7,7×1014 cm-2, 200 keV and dose 2,6 × 1014 cm-2 were implanted in the single crystal of silicon (110). The distribution profiles of implanted impurity, as well as the distribution profiles of the radiation defects in the crystal lattice, were studied by the Rutherford backscattering method in combination with channeling. The experimental results were compared with the results of simulations of binary collisions of the Monte Carlo method in the TRIM program. It is shown that the difference between the experimental data and the calculation program TRIM is more than 35% in all cases.

We report neutron production by the 2H(d, n)3He reaction induced upon the illumination of a solid nanostructured target by femtosecond laser pulses of intensity 20 PW/cm2 (1 PW = 1015 W). The target was structured through the preliminary illumination by a laser pulse of the same intensity.

The results of an experimental study and a computer simulation with the TRIM.SP code of the angular distributions of atoms sputtered from polycrystalline platinum under 3–9 keV Ne+ bombardment at normal ion incidence are presented. It was found that angular distributions of sputtered atoms are overcosine and that their shape is practically independent of an ion energy. Comparison with the previously obtained data for He+ and Ar+ ions have shown that the shape of the angular distribution does not depend on the bombarding ion species. Good agreement between experimental results and computer simulation data was found. Computer simulations of the partial angular distributions of Pt atoms ejected due to various sputtering mechanisms for Ne ion bombardment were performed and the comparison with corresponding data for He and Ar bombarding was made. The role of different mechanisms in the formation of angular distributions of sputtered atoms has been analyzed.

The results of an experimental study and a computer simulation with the TRIM.SP code of the angular distributions of atoms sputtered from polycrystalline platinum under 1.5–9 keV He + bombardment at the normal ion incidence are presented. It has been found that angular distributions of sputtered atoms are overcosine and that their shape is practically independent of the bombarding ion species and ion energy. Good agreement between experimental results and computer simulation data was found. Computer simulations of the partial angular distributions of Pt atoms ejected due to various sputtering mechanisms for He and Ar bombardments were performed. The role of different mechanisms in the formation of angular distributions of sputtered atoms has been analyzed.

The angular distributions of sputtered components were measured for NiTi polycrystalline alloy under 9 keV Ar + and He + ions bombardments with various fluences in ultrahigh vacuum. Combination of Rutherford Backscattering Spectrometry (RBS) and Auger Electron Spectrometry (AES) techniques allowed us to observe enhanced concentration of Ni over a layer with thickness comparable to a primary He + ions penetration depth due to selective sputtering of Ti atoms and radiation-induced diffusion processes. A preferential emission of Ni atoms towards the surface normal was observed during bombardment by both He + and Ar + ions. More forward-peaked “over-cosine” angular distributions of sputtered Ni in comparison with those for Ti atoms have been measured. Nonstoichiometric sputtering of NiTi alloy dependent on emission angle was observed for bombardment fluence of He + well below that needed for the steady-state altered layer formation. To explain the peculiarities of NiTi sputtering, an interpretation is discussed in terms of sputtering due to backscattered He + ions.

The angular distributions of sputtered particles for 3–10 keV argon-ion bombardment of polycrystalline platinum at normal incidence have been investigated both experimentally and by computer simulation using the program TRIM.SP. Two types of targets were used. One is a fine-grained Pt polycrystal, the other is rolled sheet Pt. The angular distributions were measured applying RBS of the material deposited on a collector. For fine-grained platinum the angular distributions are cupola shaped and slightly overcosine. For rolled platinum the distributions are much more overcosine with a strong central Wehner spot due to the texture caused by rolling. Results from computer simulation show that the effect of the surface binding energy on the shape of the angular distribution is negligible. The dependence of the shape of the angular distribution on the ion energy interval from 3.5 to 10 keV was also found to be very weak. Good agreement has been found between the experimental and computed results for fine-grained platinum.