摘要:

We report the first observation of the concentration reversible changes of defects produced by hydrogen implantation in silicon. EPR and IR-absorption measurements were used. It was found that after implantation and annealing of a sample at ∼450°C the concentration of shallow donors and the intensity of the IR-absorption bands (3.36 μm, 3.40 μm and 3.47 μm) change reversibly upon annealing at temperatures lower than 300°C. The temperature dependence of the equilibrium concentration of the shallow donors between 100°C and 300°C as well as the transients following changes in temperature have been determined. The activation energies for relaxation of a donor to a neutral state and for transition to an electrically active state are 1.23 eV and 1.74 eV, respectively. We conclude that the phenomenon is due to interaction of hydrogen atoms and intrinsic defects produced in silicon by hydrogen ion implantation.

ISSN:0033-7579    

DOI:10.1080/00337578308218598

出版商:Taylor & Francis Group    

年代:1983

数据来源: Taylor

摘要:

The velocity of the spread of discharge due to photons in 100% filled Bromine Geiger Muller Counter with three separate and divided cathodes has been determined by measuring the time in a waveform monitor taken by the discharge from the first to the third counter. Propagation velocity of discharge in a Br2counter was compared with that of an argon and alcohol mixture counter. The velocity of spread of discharge in the former lies between 0.32 × 108and 0.92 × 108cm/sec for Br2at a pressure of 10 cm Hg and in the latter, varies between 1.1 × 107and 2.7 × 107cm/sec.

ISSN:0033-7579    

DOI:10.1080/00337578308218599

出版商:Taylor & Francis Group    

年代:1983

数据来源: Taylor

摘要:

The sputtering of UF4targets by energetic beams of16O,19F, and35Cl ions has been investigated for beam energies in the range 0.12 to 1.5 MeV/amu. The sputtering yields, which follow the same trend as the electronic part of the projectile energy loss in the material, are observed to have a strong dependence on the charge state of the incident ions. Data have been taken both in transmission and reflection (0° and 180° to the incident beam direction, respectively). Energy spectra of the neutral sputtered particles have been obtained for 5 MeV19F ions and for 13 MeV35Cl ions; in both cases the spectrum has a Maxwellian form. The data obtained are compared with several models of the high energy sputtering process.

ISSN:0033-7579    

DOI:10.1080/00337578308218600

出版商:Taylor & Francis Group    

年代:1983

数据来源: Taylor

摘要:

Structural variations in 39-MeV alpha-particle irradiated (Tirr= 60°C) polycrystalline molybdenum during post-irradiation annealing were studied by X-ray and TEM methods. Despite the high density of irradiation induced defects in the structure of the specimen X-ray measurements showed zero relative lattice parameter change after an irradiation dose of 1.1 × 10−2dpa. However, during the annealing Δa/awas changed in the positive range, exhibiting two peaks—at 100 and 300°C—whereas the damage structure detected by TEM indicated no changes. Analysis of the results leads to the conclusion that in the range 100 to 250°C migration of isolated vacancies and their annihilation at interstitial clusters as well as possible formation of new vacancy clusters occur. The second peak on the Δa/atemperature dependence curve is related to the transformation (probably, thermal disintegration) of vacancy clusters formed at energetic displacement cascades during irradiation.

ISSN:0033-7579    

DOI:10.1080/00337578308218601

出版商:Taylor & Francis Group    

年代:1983

数据来源: Taylor

摘要:

Knowledge of the state and behaviour of helium in reactor components is needed in order to understand such phenomena as void swelling and high temperature radiation embrittlement. The X-ray diffraction method of lattice parameter measurement can provide useful information about the state of helium in radiation damaged lattices of metals if the effects of irradiation induced lattice defects—vacancies and interstitials as well as their agglomerates—on lattice parameter changes are taken into account.

ISSN:0033-7579    

DOI:10.1080/00337578308218602

出版商:Taylor & Francis Group    

年代:1983

数据来源: Taylor

摘要:

A new computer code, i.e., the ACAT code, has been developed to simulate atomic collisions in amorphous targets using binary collision approximation, where random targets are simulated employing the so-called cell model which is successfully used in the liquid theory. The ACAT code is used to study the backscattering and the implantation of 0.01-10 keV hydrogens on Au and on Cu. In comparing the calculated results of the ACAT code with those of the MARLOWE and TRIM codes, as a whole, an agreement between these three codes is satisfactory, and the ACAT and TRIM codes give almost the same results for energy spectra of backscattered particles and other related quantities. Using the ACAT computer code, it was found that in light ion backscattering the potential parameter as well as the inelastic energy loss parameter has an appreciable influence on the particle and energy reflection coefficients.

ISSN:0033-7579    

DOI:10.1080/00337578308218603

出版商:Taylor & Francis Group    

年代:1983

数据来源: Taylor

摘要:

Theoretical investigations on the Matsunami empirical formula for the sputtering yield are presented, and a new empirical formula is proposed. The first Matsunami empirical formula includes implicitly the effect of the inelastic stopping in one of the adjustable parameters, while in the new empirical formula the inelastic part and the elastic part are explicitly separated. It is found that the new empirical formula can predict well the energy-dependence of the sputtering yield over a wide range of the ion-target combinations.

ISSN:0033-7579    

DOI:10.1080/00337578308218604

出版商:Taylor & Francis Group    

年代:1983

数据来源: Taylor

摘要:

The annealing of γ-irradiation damage in crystalline barium nitrate at different temperatures in the range 370-430°C is a combination of a first-order process affecting a small portion of the fragments and a second-order process, with a higher energy of activation, governing the behaviour of the remainder ∼73%. The annealing data have been analysed on the models for simple interstitial vacancy recombination and also as a combination of a first-order and second-order process with an energy of activation of 10.9 and 24.0 kcal mole−1respectively. It is considered that the first-order process is the combination of close-correlated pairs of O and NO2fragments and the second order process involves the single reaction of random recombination of the fragments throughout the crystal.

ISSN:0033-7579    

DOI:10.1080/00337578308218605

出版商:Taylor & Francis Group    

年代:1983

数据来源: Taylor

摘要:

The production of disorder as a function of incident ion fiuence has been studied for various ion species on (100) GaAs at 40 K.In situmeasurements of damage were performed, using the Rutherford backscattering-channeling technique with 2 MeV He+ions. Also the effects of disorder production by the He+analysing beam on both unirradiated crystals of GaAs and on crystals previously damaged with various fluences of 40 keV N+and Bi+and 80 keV N2+have been carried out. For initial damage levels up to ∼50 % of saturation damage the He+disorder production rate was found to increase with initial heavy ion damage level. In a similar experiment using 0.5 MeV He+ions on a crystal previously irradiated with 40 keV N+, increased damage production was found which scaled approximately with the increased elastic deposited energy. Results of the study of heavy ion damage production using 20–200 keV Sb+, 40 keV N+, P+, As+, Bi+and the corresponding 80 keV diatomic implants in GaAs are discussed in terms of different cascade density regimes. In all cases, the measured disorder is greater, by up to an order of magnitude, than predicted by binary collision theory. For the heavy ion irradiations, a linear build-up of damage with fiuence is observed. For lighter ions, a superlinear dependence of damage with fiuence is observed at intermediate fluences (i.e., when the average damage level is ≳ 10% of saturation). The observed behaviour is attributed to a transition from crystalline to amorphous structure when local defect density exceeds some critical value.

ISSN:0033-7579    

DOI:10.1080/00337578308218606

出版商:Taylor & Francis Group    

年代:1983

数据来源: Taylor

摘要:

Low doses silver with energies between 5 and 25 keV were implanted in a (100) tungsten single crystal. The silver-vacancy complexes remaining after subsequent annealing were studied with thermal helium desorption spectrometry. The results show that the binding energy of one vacancy to substitutional silver is 0.8±0.3 eV, and that additional vacancies are more strongly bound. The binding energy of He to substitutional silver increased with increasing filling degree.

ISSN:0033-7579    

DOI:10.1080/00337578308218607

出版商:Taylor & Francis Group    

年代:1983

数据来源: Taylor