摘要:

The recoil implantation yield of copper and gold into silicon substrates under14N+,31P+, and40Ar+ion bombardment has been studied using the backscattering method. The dependence of the yield on the incidence energy follows Sigmund's prediction, excepted at higher energies where enhanced diffusion has been observed. Furthermore, measurements of depth distribution of recoiled atoms have been performed using the neutron activation analysis. The profiles show a maximum at a penetration depth of about 60 Å which is explained by a low-energy cross-section in the energy-depth conversion.

ISSN:0033-7579    

DOI:10.1080/00337577808240842

出版商:Taylor & Francis Group    

年代:1978

数据来源: Taylor

摘要:

The channeling of 300–400 KeV deuterons combined with the D(d,p)T reaction has been used to study the lattice location of deuterium in an fcc crystal of (Pd0.8Au0.2)D0.04and a bcc crystal of TaD0.10. The channeling angular distributions are measured for ⟨100⟩, ⟨110⟩, ⟨111⟩ axial and {100}, {110}, {111} planar directions. It is concluded that deuterium in Pd0.8Au0.2occupies the octahedral interstice of the fcc lattice, while that in Ta occupies the tetrahedral interstice of the bcc lattice.

ISSN:0033-7579    

DOI:10.1080/00337577808240843

出版商:Taylor & Francis Group    

年代:1978

数据来源: Taylor

摘要:

The bleaching effect of positron irradiation of KCl and KBr single crystals previously coloured with electrons or protons was investigated. Positrons injection in the coloured alkali halide samples reduces the F-centres concentration considerably. For KCl crystals thicker than the positrons range the appearance of additional bands in the absorption spectra is noticeable. The experimental data show that the bleaching phenomenon should be observed merely throughout the positron exposure both for irradiated and non-irradiated regions of the sample. Irradiation effects, due to positron source, on the peak counting rate of (γ-γ) angular correlation in KCl crystals under applied magnetic field were also investigated. The growth of peak counting rate shows the increase of positronium-like states formation near defects of cation sublattice.

ISSN:0033-7579    

DOI:10.1080/00337577808240844

出版商:Taylor & Francis Group    

年代:1978

数据来源: Taylor

摘要:

The Rutherford backscattering technique with 2 MeV He+ions has been used to measure the range and range straggling of ions implanted into polycrystalline aluminium and amorphous silicon with energies from 20 keV to 250 keV. In aluminium the following ions were used: Cs+, La+, Pr+, Eu+, Tb+, Dy+, Ho+, Er+, Lu+, Hf+, Pt+, Au+, TI+, Pb+, Bi+. In silicon the ions were Sm+, Eu+, Gd+, Tb+and Dy+. The data was converted into reduced range, energy and straggling coordinatesρpε and γΔRp/Řprespectively and graphs plotted against ε In the case of silicon the reduced data fell close to common curves approximated byρp= 1.46 ε0.65and γΔŘp/Řp=0.41 for 0.02 < ε < 0.24. In the case of aluminium the best fit was approximated byρP= 1.95 ε0.60and γΔŘp/Řp= 0.5 for 0.06 < ε < 0.35. The data for Ho+−Al, Au+−Al, Pt+−Si, Au+−Si and Bi+−Si deviated from the common curves over a range of energies. Calculations following the methods of Winterbon using Thomas-Fermi and Lenz-Jensen potentials produced two sets ofppversus ε curves between which all the experimental data lay, with the Thomas-Fermi curves forming a lower limit. Range data from other groups has been collected and reviewed. By combining these with our own the best experimental curves were plotted for the interval 0.0007 < ε < 10.

ISSN:0033-7579    

DOI:10.1080/00337577808240845

出版商:Taylor & Francis Group    

年代:1978

数据来源: Taylor

摘要:

The phenomenology is reviewed for several enhanced diffusion mechanisms: the normal ionization-enhanced diffusion mechanism, the Bourgoin mechanism, the energy-release mechanism and some recoil mechanisms. Application of these mechanisms are discussed for crystalline and amorphous semiconductors, super-ionic materials and insulators in radiation damage, impurity and self-diffusion, ion-implantation, and dislocation-motion-experiments.

ISSN:0033-7579    

DOI:10.1080/00337577808240846

出版商:Taylor & Francis Group    

年代:1978

数据来源: Taylor

摘要:

Mass selected energy distributions of sputtered atoms and molecules from AgBr, AgF, CdI2and PbI2have been measured using a time of flight method. The analysis of experimental data shows a complex character of the sputtering which can be explained by a simultaneous appearance of three different processes: collision cascade, thermal spike and thermal evaporation of decomposed target material. The analytical expressions for energy distributions given by the three sputtering mechanisms are in very good agreement with the experimental spectra. Physical parameters of the energy distributions:Eb(surface binding energy),Tsp(mean temperature of the spike) andT(macroscopic surface temperature) are obtained and their physical meaning is discussed. A comparison between existing sputtering theories and results of the investigations is presented.

ISSN:0033-7579    

DOI:10.1080/00337577808240847

出版商:Taylor & Francis Group    

年代:1978

数据来源: Taylor

摘要:

A commonly invoked procedure for calculating steady state nucleation rates employs a chemical kinetics argument in which the rate constants are assumed to be the same as in a so-called “constrained” equilibrium state of the system of interest. Such a procedure implicitly ignores the possibility that in some nonequilibrium nucleation processes spatial correlations among the reactants can cause the relevant rate constants to be different from their equilibrium values. Void nucleation is an example of a situation in which this phenomenon occurs. We show how to modify the usual theory to account for the local depletion of vacancies in the vicinity of a forming void. A numerical example illustrates the conclusion that the local depletion effect produces nucleation rates which can be very much smaller than those predicted by models in which there is complete spatial uniformity.

ISSN:0033-7579    

DOI:10.1080/00337577808240848

出版商:Taylor & Francis Group    

年代:1978

数据来源: Taylor

摘要:

Channeling measurements are reported which determine the radial distribution of defects, across the ⟨111⟩ and ⟨110⟩ channels, created by 20–40 keV He+, N+and Zn+bombardments of Si, GaAs and GaP at 50 K. Also the damagevs.dose data are reported for the above systems and for heavier ions, both monatomic and diatomic. The results of both sets of measurements are correlated into a consistent model in which the channeled beam backscatters off the grossly displaced atoms and small atom relaxations due to strains necessary to accommodate the damage. It is shown that at low damage levels (≲10%) the channeling technique accurately determines the number of displaced atoms,ND, but at higher damage levels, interactions with the relaxed atoms will result in an over-estimate ofND. The degree of over-estimation increases as Z1decreases and dominates for very low Z1ions. A model is developed which adequately fits the damagevs.dose behavior in which the strain-induced component is assumed proportional toND.

ISSN:0033-7579    

DOI:10.1080/00337577808240849

出版商:Taylor & Francis Group    

年代:1978

数据来源: Taylor

摘要:

A direct measurement has shown that the ionization energy required to produce electron-hole pairs in a silicon detector is independent of whether the incident 160 MeV α-particles used are channelled or not, to an accuracy of about 2%.

ISSN:0033-7579    

DOI:10.1080/00337577808240850

出版商:Taylor & Francis Group    

年代:1978

数据来源: Taylor

摘要:

The radiation chemistry of CH3I in 3-methyl pentane has been examined at 77 K in order to understand the mechanism of methyl radical decay. It was observed that for the same concentration of CH3I and equal γ dose, quickly frozen solutions gave 12 to 15% higher yields of CH3radicals and CH4as compared to slowly frozen solutions. In the latter caseG(12) was found to be higher. The differences in the yields of products have been attributed to effects caused by aggregation of solute molecules while the observed 1st order decay of CH3radicals have been attributed to its recombination with iodine atoms. The relative probability of hydrogen atom abstraction from matrix molecules as compared to homolytic dissociation of hot alkyl radicals produced by γ-radiation has been estimated in a few cases.

ISSN:0033-7579    

DOI:10.1080/00337577808240851

出版商:Taylor & Francis Group    

年代:1978

数据来源: Taylor