ISSN:1042-0150    

DOI:10.1080/10420159408219786

出版商:Taylor & Francis Group    

年代:1994

数据来源: Taylor

摘要:

The changes of the program TRIM.SP namely the vectorization and other minor changes since its first publication in 1984 are shortly described. Examples especially about backscattering and sputtering illustrate the possibilities which can be handled by the program.

ISSN:1042-0150    

DOI:10.1080/10420159408219787

出版商:Taylor & Francis Group    

年代:1994

数据来源: Taylor

摘要:

We have used the molecular dynamics (MD) technique using many-body interaction potentials to analyse in detail the processes leading to sputter emission, in order to gain a microscopic understanding of low energy bombardment phenomena. Calculations were performed for a Cu (111) single crystal surface bombarded with Ar atoms in the energy range from 10–1000 eV. The results presented for low bombarding energies are mainly concerned with the near sputtering threshold behaviour, yields and depth of origin of sputtered atoms. Furthermore, it is found, that in addition to sputtered atoms, a large number of ad-atoms at the surface are generated during the evolution of the collision cascade. At higher energies the question of cluster emission and especially their energy distribution and angular distribution are addressed. It was found that the energy distributions for the dimers and monomer atoms exhibit a similar dependence on emission energy as has been observed recently also experimentally. For atoms good agreement with the theoretical Sigmund-Thompson energy distribution was observed. However, for dimers we found that the energy distributions exhibit an asymptotic behaviour at high energies with E−3rather than with E−5, as predicted in previous modelling of cluster emission. Concerning the angular distributions six emission spots, three strong ones in the <110> and three weak ones in the <100> direction were found for atoms, but for dimers only emission spots in the <110> direction were observed, in agreement with experimental results.

ISSN:1042-0150    

DOI:10.1080/10420159408219788

出版商:Taylor & Francis Group    

年代:1994

数据来源: Taylor

摘要:

The ability of MC codes to predict the preferential sputtering of compound targets is investigated. The DYNA and TRIDYN codes are run for 3 keVAr+bombardment of aSiGebinary target. The preferential sputtering ofSiandGe, the depth dependence of the sputter cross-section and the relocation operators are calculated. Difficulties arise in trying to reproduce the experimentally reported absence of preferentiality in the sputtered flux. The models used for the surface barriers, as well as the barrier heights, influences strongly the predicted quantities. A spherical surface barrier predicts much closer to stoichiometric fluxes than a planar barrier. Different codes give different collisional diffusivities for the target species in the bulk. The need for further experiments is stressed if some guidance in the choice of input parameters in the codes is desired.

ISSN:1042-0150    

DOI:10.1080/10420159408219789

出版商:Taylor & Francis Group    

年代:1994

数据来源: Taylor

摘要:

Recently we have demonstrated the existence of the so-called sputter yield amplification (SYA) effect, based on the preferential sputtering of the lighter species during ion bombardment of composite solids and resulting in enhanced partial sputtering yield of the lighter species as compared to the elemental sputtering yield. In specific cases the enhancement of the sputtering yield could reach one order of magnitude or more. This effect has been both numerically studied and experimentally observed during low energy ion bombardment of i) thin films of low mass on heavy substrates; ii) thin films of high mass on light substrates; iii) simultaneous high mass atom deposition on light substrates; iv) simultaneous low mass atom deposition on heavy substrates. In all cases sputter yield enhancement of the low mass species is observed but in each individual case different specific goals are achieved. For example, in case i) much faster etch rate of the thin film is achieved than what is expected from the elemental sputtering yield. In cases ii) and iii) faster erosion of the target is achieved in view of sputter-deposition processes. In case iv) a nearly complete removal of the deposited species with a partial sputtering yield substantially higher than the elemental sputtering yield is achieved in view of selective ion beam assisted deposition. The SYA effect is also observed in the net growth regime, i.e. during the deposition of composite films with ion co-bombardment. In this case the composition of the growing film differs from that of the deposition flux.

ISSN:1042-0150    

DOI:10.1080/10420159408219790

出版商:Taylor & Francis Group    

年代:1994

数据来源: Taylor

摘要:

Angle resolved energy spectra for H+2scattering from Au(110) have been compared to simulations using MARLOWE and SABRE binary collision codes. The results of both simulations agree with each other but only qualitatively with the experiment. The simulations indicate that (i) contributions to the surface peak in the energy spectra come from both single and double scattering at the surface (ii) the amount of inelastic loss suffered by the scattered ion is sensitive to the loss model and (iii) azimuthal scans around the double alignment direction can be simulated quite well if an increased experimental background is included.

ISSN:1042-0150    

DOI:10.1080/10420159408219791

出版商:Taylor & Francis Group    

年代:1994

数据来源: Taylor

摘要:

Since low energy ion scattering involves collision sequences with neighbouring atoms, it is sensitive to the surface properties. The present work emphasizes the relation between ion scattering and surface dynamics on an atomic scale. A hot surface is simulated by isothermal classical dynamics with a N-body potential known to reproduce the bulk elastic properties of copper at 0 K, as well as the full bulk phonon dispersion relations within the experimental error.

ISSN:1042-0150    

DOI:10.1080/10420159408219792

出版商:Taylor & Francis Group    

年代:1994

数据来源: Taylor

摘要:

A modified version of the Monte-Carlo computer code TRIM is used to study the scattering of energetic ions from random surfaces. Angular and energy distributions of scattered particles are obtained for the ‘rough surface’ model. It is shown that the position and the magnitude of the peaks in the energy distributions of ions for a given scattering angle depend on model parameters such as the position of the surface and the number of search cylinders.

ISSN:1042-0150    

DOI:10.1080/10420159408219793

出版商:Taylor & Francis Group    

年代:1994

数据来源: Taylor

摘要:

Molecular dynamics methods are used to model the impingement of low energy ions onto crystalline targets, and the effects of these beams on thin film deposition. Simulations of the deposition of silicon films show that the structure of deposits can often be improved by the use of low energy ion beams instead of the conventional thermal beam. We examine the influence of beam energy on the formation of amorphous or crystalline deposits. The influence of ion beams on surface diffusion rates and the interdiffusion between atomic layers near the surface are also considered. Cluster deposition is treated, and the results suggest that cluster beams would be effective for depositing smooth films of materials that do not wet the substrate. We discuss the use of special purpose computers and signal processing boards to extend the time scales of molecular dynamics simulations. Rapid advances in computer hardware, algorithms, and the development of accurate interatomic potentials are dramatically increasing the power of these simulations.

ISSN:1042-0150    

DOI:10.1080/10420159408219794

出版商:Taylor & Francis Group    

年代:1994

数据来源: Taylor

摘要:

The reaction of thin Co films with Si and SiO2during ion-beam mixing with As and Ge was studied. Fluences and energies used were varied between 2-1014and 5-1015cm−2, and 15 and 200 keV, respectively. Concentration profiles of As, Ge, and Co were measured by SIMS; cross-sectional TEM-analysis was applied in order to investigate the metal-silicon interface. By comparing theoretical and experimental profiles, it was possible to separate ballistic effects from thermal processes in the Co-Si system. All theoretical profiles were calculated using the dynamic Monte-Carlo simulation program T-DYN. In case of Co-SiO2interaction, it could be shown that the Co distribution in the oxide was only caused by recoil implantation and not by diffusion processes or reactions.

ISSN:1042-0150    

DOI:10.1080/10420159408219795

出版商:Taylor & Francis Group    

年代:1994

数据来源: Taylor