In this paper, the results of experiments on irradiation of the multiwall carbon nanotube (MWNT) samples by argon ions with energy of 1 keV are presented. They were obtained by energy loss spectroscopy of reflected electrons and Auger electron spectroscopy.

It was found that ion irradiation of MWNTs decreases the characteristic energy and increases the full width at the half of the maximum (FWHM) of the π-plasmon peak. The plasmon relaxation time was found.

A computer code has been developed to solve numerically the Howie-Basinski equations of electron diffraction theory, and has been applied to simulate diffraction contrast images of small dislocation loops under weak-beam diffraction conditions. In this paper we describe the basis of the code, and apply it to simulate weak-beam images of small loops under a variety of imaging conditions.

Rutile (TiO2) single crystals of (110) or (001) orientation were irradiated by high fluence protons with the energy of 0.5, 4.9 and 18 MeV and with the fluence of 1×1018 and 1.9×1022 m-2. UV-VIS-IR, LRS and HRTEM were used to analyze the optical absorption and microstructure of samples. The UV-VIS-IR results showed that proton irradiation induces two absorption peaks centered at 760 and 1700 nm respectively, even high fluence irradiation induces absorption plateau at 600∼2500 nm. LRS results showed that the related intensity of common vibration modes is different for different planes. Proton irradiation induces the vibration frequency and related intensity change for inherent LRS modes, and several new vibration modes also appear. High fluence proton irradiation induced large defect clusters, i.e. stacking faults, which is demonstrated by HRTEM observation. The optical absorption mechanism also has been discussed.

Germanium implantation into silicon substrate is currently used to preamorphisize the crystalline structure in order to avoid boron channeling effects in shallow P+N junction manufacturing. Nevertheless, after boron doping and rapid thermal annealing, different defects are formed within the structure, such as end of range defects which are created at the amorphous/crystalline interface. Our study concerns two types of shallow P+N junctions. These junctions were fabricated using low energy boron implantation at 3 KeV with a dose of 2×1015 cm-2 into high-energy germanium preamorphized n-type crystalline silicon substrates at 2.2 MeV with a dose of 1015 cm-2. In the first type, the preamorphization was performed at ambient temperature. In the second, the preamorphization was performed at liquid nitrogen temperature. Boron doping was followed by a Rapid Thermal Annealing (RTA) step for 15 s at 950 °C. Deep Level Transient Spectroscopy (DLTS) technique was used to characterize the defects formed in each structure. The impact of an ac magnetic field on the reverse current has been studied at a given bias, when sweeping the sample temperature. The measurements were performed under a low frequency (less than 1 kHz) magnetic field of a Vrms value of 2000 G, with sample temperature varying between 80 and 260 K. The results show a high activity of defects at low frequencies (1 and 10 Hz) for the nitrogen preamorphized sample. Moreover, this activity is observed at about 200 K which corresponds to the peak of the DLTS spectra of such sample. However, the ambient preamorphized sample characterized by a lower concentration of defects seems to be insensitive to the ac magnetic field. Therefore, it appears that the preamorphization-induced defects influence strongly the response of the junction to an applied ac magnetic field.

We have studied high-energy ion irradiation effects in bismuth by measuring the electrical resistivity at low temperature in relation to its structural change. Bismuth thin films (330–520 Å thick) are irradiated below ∼10 K with energetic (150–200-MeV) heavy ions. The resistivity of the specimen is measured in situ below ∼7.2 K during the irradiation. After the irradiation, annealing behavior of the resistivity is observed up to ∼30 K. The temperature dependence of the resistivity during annealing shows an abrupt increase around 20 K, implying re-crystallization of irradiation-induced amorphous regions. We have tried to detect a superconducting transition which may take place as a result of irradiation-induced amorphization. In the range of the measuring temperature down to ∼4.9 K, resistivity decrease due to superconducting transition has not been observed in the temperature dependence of the resistivity after 200-MeV 197Au ion irradiation up to a fluence of 3.1×1012 cm-2.

The evolution of surface morphology during ion beam erosion of Si(111) at glancing ion incidence (60° from normal, 500 eV Ar+, 0.75 mA/cm2 collimated beam current) was studied over a temperature range of 500–730° Celsius. Keeping ion flux, incident angle, and energy fixed, it was found that one-dimensional sputter ripples with wavevector oriented perpendicular to the projected ion beam direction form during sputtering at the lower end of the temperature range. For temperatures above approximately 690° Celsius, growth modes both parallel and perpendicular to the projected ion beam direction contribute to the surface morphological evolution. This effect leads to the formation of bumps (“dots”) with nearly rectangular symmetry.

Metal nanoclusters (NCs) of lithium, zinc, silver and gold embedded in MgO were created by means of ion implantation of Li, Zn, Ag and Au ions into single crystals of MgO(100) and subsequent thermal annealing. Nanoclusters of the compound semiconductor CdSe were obtained by implantation of both Cd and Se ions. Solid noble gas clusters were formed by Kr ion implantation. Optical and structural properties of the NCs were investigated using optical absorption spectroscopy (OAS), high-resolution X-ray diffraction (XRD) and cross-sectional transmission electron microscopy (XTEM). The mean nanocluster size is estimated from the broadening of the Mie plasmon optical absorption bands using the Doyle formula. These results are compared with the NC size as obtained from XRD (using the Scherrer formula) and from direct XTEM observations. The three methods are found to be in reasonable agreement with a mean size of 4.0 and 10 nm found for the Au and Ag clusters, respectively. Using TEM observations, the relative interface energies of MgO//Au and MgO//Ag interfaces are also determined. In the case of MgO//Au, they are found not to be in agreement with theoretical predictions in the literature. CdSe nanoclusters were found to adopt different crystal structures dependent on the size. Small ones (<5 nm) appear to have a rock salt structure, larger ones the sphalerite structure. The solid krypton NC's are under high pressure. The pressure of individual Krypton bubbles was determined from the moiré fringes

Natural short-lived radionuclides generate electronic defects in minerals, such as trapped electrons and positive holes, often associated with element impurities, which act as final traps over geological periods. Two main examples will be illustrated. The first example will concern the point defects, which are observed in clay minerals. The high specific surface area makes clay minerals sensitive to the geochemical radiation background and provides a record of the past occurrence of radionuclides in geological systems. In kaolinite, three types of hole-centers are trapped by oxygen atoms linked to Si- or Al-sites. An experimental dosimetry gives the paleodose, which can be used either to assess mean past U-concentration or for kaolinite dating, depending on the available geochemical parameters. The detection of past migrations of radioelements in natural analogues may be used in the safety assessment of radioactive waste disposals. The second example will concern the role of mineral impurities in defect formation and stabilization. Natural fluorites (CaF2) exhibit hole-and electron-centers trapped on several rare earths and oxygen impurities, often present at the ppm level, which are responsible for the wide range of coloration observed in natural fluorites. Ca colloids may form under severe irradiation and give rise to a characteristic absorption. The thermal stability of radiation-induced defects gives constraints on the evolution of fluorites as a function of temperature and time. Other minerals, such as apatite, confirm the importance of impurities in stabilizing radiation-induced defects over geological periods.

Progress on separating the long-lived fission products from the high level radioactive liquid waste (HLW) has led to the development of specific host matrices, notably for the immobilization of cesium. Hollandite (nominally BaAl2Ti6O16), one of the main phases constituting Synroc, receives renewed interest as specific Cs-host wasteform. The radioactive cesium isotopes consist of short-lived Cs and Cs of high activities and Cs with long lifetime, all decaying according to Cs+→Ba2++e- (β) + γ. Therefore, Cs-host forms must be both heat and (β,γ)-radiation resistant. The purpose of this study is to estimate the stability of single phase hollandite under external β and γ radiation, simulating the decay of Cs. A hollandite ceramic of simple composition (Ba1.16Al2.32Ti5.68O16) was essentially irradiated by 1 and 2.5 MeV electrons with different fluences to simulate the β particles emitted by cesium. The generation of point defects was then followed by Electron Paramagnetic Resonance (EPR). All these electron irradiations generated defects of the same nature (oxygen centers and Ti3+ ions) but in different proportions varying with electron energy and fluence. The annealing of irradiated samples lead to the disappearance of the latter defects but gave rise to two other types of defects (aggregates of light elements and titanyl ions). It is necessary to heat at relatively high temperature (T=800°C) to recover an EPR spectrum similar to that of the pristine material. The stability of hollandite phase under radioactive cesium irradiation during the waste storage is discussed.

Recently etched heavy ion tracks in MOS devices were filled with (semi)conducting materials to enable charge extraction from, or injection into the conducting channel below the Si/oxide interface, respectively. This leads to a family of novel electronic devices that we denoted as “TEMPOS” structures - that acronym stands for “Tunable Electronic Material with Pores in Oxide on Silicon”. In comparison with MOS-FETs, TEMPOS structures have some unique properties due to their additional parameters such as the track diameter, density, and shape, and the material embedded therein and its spatial distribution. This makes these novel structures much more complex, and it eventually leads to higher compactation of the TEMPOS circuits and to unexpected electronic properties. Depending on the choice of these parameters and the working point of these structures, TEMPOS elements can overtake the function of gatable resistors, condensors, photocells, hygrocells, diodes, sensors, and others. This work concentrates on some basic aspects of TEMPOS and gives some corresponding current /voltage relations and equivalent circuits.

We combine simulation, theoretical and experimental results to study radiation damage effects in complex oxides under irradiation. In zircon, we study large density variations in the damaged structure, and show how damage percolation results in the enhanced transport extending to macroscopic lengthscale, and suggest that percolation threshold serve as a benchmark for acceptable waste load in a waste form. In perovskite, we identify common defects in the damaged structure, and relate their stability to chemical bonding. Finally, we formulate the criterion for resistance to amorphization by radiation damage: a material is amorphizable if it is able to form a covalent network.

The kinetics of alkali ion exchange of irradiated glasses were investigated using the structural energy barrier model for ion exchange of glasses. Derived rates of alkali ion exchange depend both on irradiation dose D(Gy) and dose rate q(Gy/s) illustrating that some effects cannot be simulated by external irradiation and require in-situ measurements. Higher D and q lead to increased ion exchange rates. Significant changes occur in the activation energies demonstrating a 4 – 6 times decrease depending on glass composition. Radiation-induced changes are higher at relatively low temperatures and are diminished by increased glass temperature. Numerical estimations show that changes in alkali ion exchange kinetics occur at D far below damaging doses.

Nucleation of gold nanoclusters in TiO2(110) single crystal using ion implantation and subsequent annealing were studied by Rutherford backscattering spectrometry /channeling (RBS/C), scanning electron microscopy (SEM) and transmission electron microscopy (TEM). Approximately 1000 Au2+/nm2 were implanted at room temperature in TiO2(110) substrates. TEM and SEM measurements reveal that rounded nanoclusters were formed during the implantation. In contrast, subsequent annealing in air for 10 hours at 1275 K promoted the formation of faceted (rectangular shaped) Au nanostructures in TiO2. RBS channeling measurements further reveled that Au atoms randomly occupied the host TiO2 lattice during the implantation. However, it appears that some Au atoms moved to the Ti lattice positions after annealing.

The present work focuses on the γ-ray irradiation doses and conditions (dry solid state, solid state dispersing in 0.5–2 % aqueous H2O2 solution, solid state dispersing in 1% aqueous acetic acid, and 2% aqueous K2S2O8) to determine the level that the molecular weight of chitosan is lowered significantly without changing its primary structure. Molecular weight of chitosan (105-106 Dalton) is reduced approximately 50% under the γ-ray dose of 20 kGy in the dry solid state. The decrease in molecular weight is enhanced up to 80% when chitosan is suspended in 0.5–2 % aqueous H2O2 solution during γ-ray irradiation. In either condition, the backbone structure of the irradiated product is maintained with little change in the terminal chain. In the cases of (i) chitosan suspended in 2% aqueous K2S2O8 and (ii) chitosan in 1% aqueous acetic acid, chitosans lose their primary structures and physical properties.

Metal-semiconductor structures based on composite semiconductors A1B5C6 are investigated as possible γ-ray detectors. Electric measurements carried out on the samples before the irradiation have exhibited no special peculiarities. After irradiation the analogous investigations have shown dramatic changes of charge carriers transport. Numerical analysis showed the field-current characteristics similar to the p-n-homo-junction: the forward current is described by the power law I∼(Fa)3/2, where Fa stands for applied electric field. Under reverse bias two clear modes of the carriers transport are observed: under the so-called threshold field FTR ∼ 300 V/m the experimental current is governed by quasi-ohmic law I∼(Fa)0.8; as the applied field exceeds the threshold value, the field-current dependence points out the strong trap-assistant tunneling processes: I∼(Fa)5.

By computer simulation details have been observed regarding the dynamics of the change of the character of trajectories, the range and energy losses of channeled ions, as well as the angular and energy distributions of ions transmitted through thin crystal versus the composition of single crystal, the impact parameters from the center of the channel and the initial energy. It has been established that for a paraxial part of a channeled beam the inelastic energy losses comprise the main loss of energy. The elastic energy losses of the channeling ions in the case of Cu3Au(100) crystal are larger than in the case of Cu(100). As Au atoms are heavier than Cu atoms, in the case of Cu3Au(100) the degree of the dechanneling of particles is greater and the range is smaller in comparison with the similar characteristics for Cu(100).

Electron irradiation-induced modifications in two glasses, K2O – SiO2 and Au doped Na2O – B2O3 – SiO2, were observed in electron microscope. The products of modifications were “nano-particle” like contrasts in transmission electron microscopy (TEM) images, which can be easily confused with real nano-particles and phase separation. The driving force for the modifications in the glasses is the tendency of elimination of non-bridging oxygen (NBO) through the removal of cations. The phase separation into cation rich and poor region is their nature under electron irradiation. Therefore, it is absolutely essential to record in situ frames when the TEM images are used to provide microstructure information of glasses. Additionally, charging effects in glasses have also been discussed.

Effects of Ar+ ion irradiation on solid-phase growth of β-FeSi2 have been investigated. Si substrates were amorphized with Ar+ ions (20 keV) before Fe (15 nm) deposition to form Fe(15 nm)/a-Si/c-Si stacked structures. As a reference, Fe/c-Si stacked structures were prepared. In the initial stage of annealing at 800 °C, β-FeSi2 formation was enhanced for pre-amorphized samples, which was due to the enhanced diffusion of silicidation species. In the long time annealing, β-FeSi2 formation proceeded by thermal equilibrium diffusion, and the formation rate was not affected by pre-amorphization. Crystal quality of β-FeSi2 was improved by pre-amorphization. The pre-amorphization enhanced diffusion is useful for formation of high quality β-FeSi2 thin films.

64-keV Ni ion implantation was performed at room temperature up to a dose of 1×1017 cm-2 in α-Al2O3 single crystals. The charge states, structure and optical properties of metallic embedded Ni nanoparticles were studied by using X-ray photoelectron spectroscopy (XPS), transmission electron microscopy (TEM) and optical spectroscopy, respectively. XPS analysis showed that implanted Ni ions are mainly in charge state of metallic Ni0. Nanoparticles distributed from the surface to 30 nm below the surface were observed in a bright-field cross-sectional image. The size of nanoparticles ranges from 1 to 5 nm in diameter. A selected area electron diffraction (SAED) pattern shows Ni nanoparticles with lattice parameter a = 0.352 nm. A high-resolution electron microscopy (HREM) image indicated the Ni-implanted area had been entirely amorphized. A new broad absorption band centered at 400 nm appeared in the optical absorption spectrum of the as-implanted crystal, due to surface plasma resonance (SPR) of Ni nanoparticles.

The focused ion beam has been acknowledged as a versatile tool for local sputtering as well as local deposition of material. A beam diameter below 10 nm is feasible and renders FIB a powerful tool for microstructure fabrication and generation. This experimental study investigates the geometrical limitations of FIB processing as well as the implications on the processed material. The high energetic ions of the primary beam also change the properties of the processed material due to implantation and atomic mixing. The incorporation of Ga from the FIB may be beneficial in the case of deliberate implantation or unfavorable as a chemical impurity. Higher doses of ion irradiation caused amorphisation of the material. The effects of FIB processing on the substrates as well as deposited structures are illustrated.