Pattern transition from nanohoneycomb to nanograss on germanium by gallium ion bombardment

During the irradiation of Ge surface with Ga+ions up to 1017ions·cm-2, various patterns from ordered honeycomb to nanograss structure appear to be decided by the ion beam energy. The resulting surface morphologies have been studied by scanning electron microscopy and atomic force microscopy. For high energy Ga+irradiation(16–30 ke V), by controlling the ion fluence, we have captured that the equilibrium nanograss morphology also originates from the ordered honeycomb structure. When honeycomb holes are formed by ion erosion, heterogeneous distribution of the deposited energy along the holes leads to viscous flow from the bottom to the plateau. Redistribution of target atoms results in the growth of protuberances on the plateau, and finally the pattern evolution from honeycomb to nanograss with an equilibrium condition.     

Radiation-enhanced diffusion of boron in germanium during ion implantation

An effect of radiation-enhanced diffusion during boron ion implantation into 200-500°C germanium substrates has been found. The boron-enhanced diffusion coefficient is independent of the temperature over the range 200-500°C during ion implantation, depends upon the dose rate of the incident ions and its value corresponds to the thermal diffusion of boron in germanium at 800°C.     

Distribution of boron and phosphorus ion paths in amorphous germanium

Distributions of the projected paths of boron and phosphorus ions with energies E = 25–150 keV in germanium are obtained experimentally and by means of Monte-Carlo calculations. Good agreement is established between the calculated and experimental data for boron ions. Phosphorus experimental paths are 30% less than calculated. It is shown that it is not possible to explain the discrepancy by the lack of correspondence of the true electronic deceleration to the value calculated according to the Lindhard-Scharff theory. The results are discussed from the viewpoint of the influence of shell effects on the elastic and inelastic deceleration of the ions.Translated from Izvestiya VUZ. Fizika, Vol. 15, No. 1, pp. 43–49, January, 1972.     

Lattice dilatation of boron in silicon

Recent data on laser-annealed, boron-implanted silicon are analysed, and the results compared with earlier experiments and simple theory. Each substitutional boron decreases the total volume by about 90% of the volume per silicon atom in the perfect crystal.     

Sputtered atom ejection from Ge and the annealing of ion bombardment induced disorder

It has been previously established that it is necessary to keep single targets of Ge and Si above a certain critical temperature T_a before one can obtain an ejection pattern indicative of surface order. In the following work, we report on the dependence of the disorder to order transition temperature, T_a on the incident ion mass, the dose rate and the crystallography of the target. The disorder to order transition temperature, T_a has been measured for 5, 10 and 15 keV Ar⁺, K⁺ and Ne⁺ bombardment of (111), (110) and (100) Ge, using the sputtered atom ejection pattern to indicate the restitution of order. The dose rate dependence of the transition temperature, T_a , was used to calculate activation energies for the transition occurring.     

Potassium and titaniumKX-ray de-excitation induced by ion bombardment

KX-ray de-excitation spectra have been produced for K and Ti by proton, alpha and oxygen ion beam bombardment. These spectra have been measured with a crystal spectrometer of resolution (FWHM) of 10 and 13 ev for theKα_1,2 line in K and Ti respectively. The additional lines not found in the normal X-ray spectra are attributed to multiple inner shell ionization. The energy shifts and relative intensities of these lines are compared to theoretical predictions.     

Propulsion of ripples on glass by ion bombardment

The propulsion of surface ripples on SiO(2) by an ion beam was investigated by in situ electron microscopy. The observed propagation of the ripples contradicts existing models for ion-beam-induced ripple development. A new model based on the Navier-Stokes relations for viscous flow in a thin layer is introduced. It includes inhomogeneous viscous flow, driven by spatial variations in the deposition of the energy of the ion beam. The model explains the observed reversed propagation. The hitherto unknown propulsion mechanism is important for understanding nanoscale pattern formation by ion bombardment.     

Auger electron emission by ion bombardment of light metals

The energy distribution of secondary electrons ejected from a metallic target upon ion bombardment (Ar⁺, 10 keV) is studied with a 180° magnetic analyser, particularly in the vicinity of the Auger peaks that appear in the electron spectra of the light metals (Li, Be; Na, Mg, Al, Si). A qualitative explanation based on the correlation diagrams which described the evolution of the electronic levels during the collision of two atoms inside the target is proposed to interpret the variation of the Auger peak intensity with the atomic number of the target.     

Spatially nonlocal model of surface erosion by ion bombardment

A model of solid surface erosion under ion bombardment is proposed. This model takes into account the dependence of the local sputtering yield on the nanoscale relief at a given point and the point of incidence of a primary ion. Such an approach leads to spatially nonlocal erosion model, which predicts the formation of a wavelike relief in the presence of nanoscale inhomogeneities on the surface.     

Diffusion effects in ion implanted germanium

During isochronal anneal sequences the number of Hg, Tl and Bi atoms implanted into Ge has been found to decrease. This decrease occurs for all three species and has been observed for samples implanted at room temperature as well as for hot implants (300—350°C). The decrease starts at anneal temperatures of 350—550°C. Similar results have been obtained for In and Sb implanted Ge. For samples implanted with Hg to doses leading to amorphous layers, the decrease in the number of implanted atoms seems to be related to the reordering of the amorphous layer. The experiments show that no diffusion of the implanted atoms into the bulk material occurs and the decrease observed is attributed to be a diffusion of the atoms to the surface followed by outdiffusion, thermal etching or both.     

Surface segregation of PdAg alloys induced by ion bombardment

A Pd-rich phase has been observed to segregate on the surface of PdAg alloys under the influence of 500 eV Ar⁺ and N₂⁺ bombardment. By examining the X-ray photoemission spectra of these surfaces, we report changes in the structure of the Pd 3d peaks which are specifically linked to this phase. Studies of the spectral changes with Ar⁺ dose show that one $\text{Pd 3d}{}_{\mathrm{<mtext>5</mtext><mtext>2</mtext>}}$ peak arises from electrons originating from the altered overlayer and a second $\text{Pd 3d}{}_{\mathrm{<mtext>5</mtext><mtext>2</mtext>}}$ peak arises from the underlying alloy with a binding energy dependent on the underlying concentration. The altered layer is found to vary in thickness between one and five layers, depending on the bulk alloy concentration. The thickness of this layer is also dependent on the nature of the primary ion since a different altered layer thickness is found using nitrogen ion bombardment.     

Analysis of cardiac tissue by gold cluster ion bombardment

Specific molecules in cardiac tissue of spontaneously hypertensive rats are studied by using time-of-flight secondary ion mass spectrometry (TOF-SIMS). The investigation determines phospholipids, cholesterol, fatty acids and their fragments in the cardiac tissue, with special focus on cardiolipin. Cardiolipin is a unique phospholipid typical for cardiomyocyte mitochondrial membrane and its decrease is involved in pathologic conditions. In the positive polarity, the fragments of phosphatydilcholine are observed in the mass region of 700-850 u. Peaks over mass 1400 u correspond to intact and cationized molecules of cardiolipin. In animal tissue, cardiolipin contains of almost exclusively 18 carbon fatty acids, mostly linoleic acid. Linoleic acid at 279 u, other fatty acids, and phosphatidylglycerol fragments, as precursors of cardiolipin synthesis, are identified in the negative polarity. These data demonstrate that SIMS technique along with Au₃⁺ cluster primary ion beam is a good tool for detection of higher mass biomolecules providing approximately 10 times higher yield in comparison with Au⁺.     

The in situ cleaning of specimens in the field ion microscope by argon ion bombardment

The extensive adoption of argon bombardment cleaning techniques for specimens used in LEED and Auger studies, and the frequent, and often difficult, requirement of preparing field ion emitters, and their supports, free from contamination, led to the investigation of in situ argon ion bombardment of specimens in the field of ion microscope, both from the point of view of the efficiency of the cleaning process, and the investigation of ensuing surface and lattice damage, a task to which the technique of field ion microscopy is particularly appropriate.Experiments were carried out in some detail for tungsten specimens, and subsequently extended to the hexagonal metal, rhenium, with a view to obtain information on the thermally annealed end forms of such metals. In both cases, very small radius clean thermally annealed specimens could be prepared.     

Synthesis of amorphous boron carbide by single and multiple charged boron ions bombardment of fullerene thin films

In this paper, results of structural modification of fullerene thin films by single and multiple charged boron ions (B⁺, B³⁺) are presented. The applied ion energies were in the range of 15-45 keV. The characterization of as-deposited and irradiated specimens has been performed by atomic force microscopy, Raman and Fourier transform infrared spectroscopy and UV/vis spectrophotometry. The results of Raman analysis have shown the formation of amorphous layer after irradiation of fullerene thin films. Fourier transform infrared spectroscopy has confirmed the formation of new B-C bonds in irradiated films at higher fluences (2 × 10¹⁶ cm⁻²). The morphology of bombarded films has been changed significantly. The optical band gap was found to be reduced from 1.7 to 1.06 eV for irradiated films by B³⁺ ions and 0.7 eV for irradiated films by B⁺ ions.     

Multiple processes during the sputtering of materials by ion bombardment

A new method of statistical analysis dedicated to filling the gap between dynamic and thermodynamic theories of secondary-particle emission under ion bombardment is proposed. Expressions for the average number of emitted atomic particles and electrons are obtained, and the relationships between their yields are established.     

Cone shape evolution under ion bombardment

The evolution of the profile of a cone developing under ion bombardment on the etch pit bottom has been investigated by computer simulation taking into account sputtering and ion-induced migration of atoms. A twofold increase in the cone apex angle is observed, which is accompanied by the appearance of kinks on its generatrix. A plateau arises on the pit bottom and a circular parapet is formed above the flat surface.