摘要:

TRIM type binary collision approximation event store codes have employed to simulate collisional effects which occur during ion-beam or plasma assisted deposition of thin films.

ISSN:1042-0150    

DOI:10.1080/10420159408219796

出版商:Taylor & Francis Group    

年代:1994

数据来源: Taylor

摘要:

A characteristic of ion mixing in the low temperature portion of the thermally assisted ion mixing regime is that the activation energy obtained from most experiments is in the range of 0.1 to 0.3 eV. These values are typically a factor of 4 to 10 lower than the vacancy migration energy of most elements. This discrepancy is maintained even when the ion mixing data is contrasted to the more comparable data from concentrated homogeneous alloys. It appears that an explanation of the ion mixing activation energy is not possible by radiation enhanced diffusion (RED) where, at the low temperature end of RED, defect annihilation is by direct vacancy-interstitial recombination and the predicted activation energy is Q = 0.5 EMv

ISSN:1042-0150    

DOI:10.1080/10420159408219797

出版商:Taylor & Francis Group    

年代:1994

数据来源: Taylor

摘要:

Using the hybrid Monte Carlo simulation code ACAT-DIFFUSE, we have investigated the two-component target sputtering and the associated stoichiometric changes near the surface, where we employed PdxPt1−xas a two-component alloy. The present ACAT-DIFFUSE code can estimate the slowing down process of energetic ions and the thermal process of moderated atoms. If the surface segregation is ignored, the simulation showed that the Pd signal of Auger electron spectroscopy (AES) should be larger than that of low energy ion scattering spectroscopy (ISS). If the segregation energy and the associated effective diffusion constant are properly selected, the simulated ISS values and the AES values of the Pd concentration are in good agreement with the experimental ISS and AES values.

ISSN:1042-0150    

DOI:10.1080/10420159408219798

出版商:Taylor & Francis Group    

年代:1994

数据来源: Taylor

摘要:

Channeling effects in ion implantation are reviewed comparing experimental data with Monte Carlo simulations. B, and P ions at energies ranging from 0.5 and 1 MeV were implanted along the [100], [111], and [110] axes or in a random direction of silicon wafers. Profiles were obtained either by secondary ion mass spectrometry or by spreading resistance analyses after a rapid thermal annealing procedure. The maximum penetration and the electronic stopping were determined as a function of the beam energy and axial directions. A semiempirical approach based on the Oen Robinson formula is proposed to simulate the experimental data. Isoconcentration contour lines at the substrate doping level were obtained by a new two-dimensional delineation technique based on spreading resistance profiling. The lateral distribution of ions implanted in a random direction is always broader than that of ions implanted with the same energy along the [100] axis. These results are correlated to the reduced nuclear encounters experienced by an ion moving in a channel with respect to that one moving in a random trajectory

ISSN:1042-0150    

DOI:10.1080/10420159408219799

出版商:Taylor & Francis Group    

年代:1994

数据来源: Taylor

摘要:

An introduction to channeling and channeling (Kumakhov) radiation is given. Relativistic and quantum-mechanical effects are discussed in function of the electron or positron energy. Phenomena of Quantum Electrodynamics in strong macroscopic field, which can be tested in channeling conditions, are described. Recipees for semi-classical Monte-Carlo simulations are presented and one of them compared with experiments at 10 and 150 GeV.

ISSN:1042-0150    

DOI:10.1080/10420159408219800

出版商:Taylor & Francis Group    

年代:1994

数据来源: Taylor

摘要:

Energetic particle bombardment of semi-conductors (SiandGaAs) is studied by means of Molecular Dynamics simulations using many-body potentials. The simulations show that the diamond lattice structures can lead to the trajectories of particles within the crystal being channelled even at low energies. Some results concerning damage production, low energy implantation profiles and angular distributions of ejected particles are presented.

ISSN:1042-0150    

DOI:10.1080/10420159408219801

出版商:Taylor & Francis Group    

年代:1994

数据来源: Taylor

摘要:

Channeling profiles of 5–200 keVB+, 100–500 keV P+and 40–300 keV As+implanted near <100> and <110> axes in crystal silicon are calculated using the binary collision approximation code CRYSTAL. Calculated profiles are compared to carefully chosen experimental ones. Also, high dose phosphorus profiles with damage accumulation are compared to published experimental data.

ISSN:1042-0150    

DOI:10.1080/10420159408219802

出版商:Taylor & Francis Group    

年代:1994

数据来源: Taylor

摘要:

The processes of radiation damage, from initial defect production to microstructure evolution, occur over a wide spectrum of time and size scales. An understanding of the fundamental aspects of these processes requires a spectrum of theoretical models, each applicable in its own time and distance scales. As elements of this multi-model approach, molecular dynamics and binary collision simulations play complementary roles in the characterization of the primary damage state of high energy collision cascades. Molecular dynamics is needed to describe the individual point defects in the primary damage state with the requisite physical reality. The binary collision approximation is needed to model the gross structure of statistically significant numbers of high energy cascades. Information provided by both models is needed for connecting the defect production in the primary damage state with the appropriate models of defect diffusion and interaction describing the microstructure evolution. Results of binary collision simulations of high energy cascade morphology are reviewed. The energy dependence of freely migrating defect fractions calculated in recent molecular dynamics simulations are compared to results obtained much earlier with a binary collision/annealing simulation approach. The favorable agreement demonstrates the viability of the multi-model approach to defect production in high energy cascades.

ISSN:1042-0150    

DOI:10.1080/10420159408219803

出版商:Taylor & Francis Group    

年代:1994

数据来源: Taylor

摘要:

Molecular dynamics simulations of low-energy atomic recoils have been carried out for α-Ti (HCP) with a view to investigating the displacement threshold energy, Ed, in detail. These have been undertaken at 0 K and 100 K, using a many-body interatomic potential modified to reflect the dominant two-body interaction at short range. This is the first systematic study of atomic displacement events in the HCP structure using such a potential. The mechanisms of these threshold events have been investigated and the strong orientation dependence of the threshold energy has been interpreted in terms of the HCP crystal structure. Also, a correlation has been found between the magnitude of the threshold displacement energy and the maximum number of atoms temporarily displaced into interstitial positions during a cascade.

ISSN:1042-0150    

DOI:10.1080/10420159408219804

出版商:Taylor & Francis Group    

年代:1994

数据来源: Taylor

摘要:

Depth profiles of nitrogen implanted into Zr with an energy of 50 keV were calculated by dynamic SASAMAL code with three different assumptions for the diffusion of excess atoms over stoichiometry, i.e., ‘no diffusion', ‘both-sides-diffusion’ and ‘upward-diffusion'. To distinguish nitrogens implanted certain stage of implantations, alternate implantations of15N and14N were used. The results were compared with the experimental results by the resonance nuclear reaction analysis, NRA. For15N implantation with fluences from 1 × 1017to 1 × 1018ions/cm2, the calculated results with ‘upward-diffusion’ agreed very well with the NRA results for all fluences. For the depth profile of pre-implanted15N (1 × 1017ions/cm2), which was changed by the subsequent14N implantation with fluences of 1 ∼ 10 × 1017ions/cm2, the agreement with the NRA results was satisfactory until the14N fluence did not exceed 5 × 1017ions/cm2, but for higher fluences, the retained probabilities of15N obtained by the ‘upward-diffusion’ code were too low compared with the experimental value obtained by NRA. For the depth profiles of15N (1 × 1017ions/cm2) implanted following after implantations of14N with fluences of 1 ∼ 10 × 1017ions/cm2, the agreement with the NRA results was quite good for all14N fluences. It is concluded that the approximation of ‘upward-diffution’ is proper satisfactorily for the treatment of atoms implanted at the final stage of implantations, but a problem is left for the treatment of atoms implanted at the early stage of implantations.

ISSN:1042-0150    

DOI:10.1080/10420159408219805

出版商:Taylor & Francis Group    

年代:1994

数据来源: Taylor