摘要:

The production and removal of radiation defects in Ge (110) single crystals are studied by measuring the variation in the kinetic secondary electron emission yield during bombardment by 40 keV Ge ions. A strong dose rate effect has been found in the temperature dependence of the defect production. An activation energy of 1.44 eV has been calculated for the defect which plays an important role in the removal of damage in Ge.

ISSN:0033-7579    

DOI:10.1080/00337577208231124

出版商:Taylor & Francis Group    

年代:1972

数据来源: Taylor

摘要:

Results are presented of capacity as a function of reverse bias for GaAsp+nsolar cells before and after irradiation by fast electrons. The effect on capacity measurements of the presence of additional donor or acceptor defects on then-type side is disccssed theoretically. It is shown that a variety of characteristic effects can occur depending on the position of the defect energy level in the band gap and the associated time constant for electron emission and capture. It is deduced that the defects introduced by irradiation with a predominant influence on the results were a uniform concentration of deep acceptors with levels in the upper half of the gap. Other defects with deep levels in the top half of the gap were present before irradiation. The time constants were greater than 3 × 10−3secs. It is inferred that the levels of other acceptors known to be introduced by electron irradiation are shallow and in the top half of the gap, and those of donors in the lower half. More tentatively it is concluded that few, if any, donor defects were introduced by irradiation with levels in the top half of the gap, or acceptor defects with levels in the lower half. The pre-irradiation impurity and defect concentration was essentially both uniform and unaffected by the irradiation. It is also deduced that the formation of an abruptp+-i-nstructure does not appear to be a mechanism affecting the results. After irradiation some recovery in the capacity values occurred after a long period at room temperature.

ISSN:0033-7579    

DOI:10.1080/00337577208231125

出版商:Taylor & Francis Group    

年代:1972

数据来源: Taylor

摘要:

Protons in the region of 400 KeV have been used to study the channeling process in BaF2and CaF2. The rate of loss of protons from the 111 linear channel, stopping power, and critical angle for the channel were found. Two techniques were employed, namely observationof elastic scattering by the lattice ions, and alpha particles produced by the reaction19F(p,αy)16O, from the sharp resonance at 340 keV. Both techniques gave results in good agreement. The channel parameters were much closer together for the two crystals than had been anticipated on the basis of the large difference in charge between Ba and Ca.

ISSN:0033-7579    

DOI:10.1080/00337577208231126

出版商:Taylor & Francis Group    

年代:1972

数据来源: Taylor

摘要:

The spatial distributions of fast particles ejected from silicon and germanium targets bombarded with 10–30 keV energy noble gas ions have been experimentally studied. All the experiments were performed for both crystalline and amorphized target surfaces. The obtained distributions were found strongly influenced by the crystalline structure of the target.

ISSN:0033-7579    

DOI:10.1080/00337577208231127

出版商:Taylor & Francis Group    

年代:1972

数据来源: Taylor

摘要:

A simple theory of the swelling of materials subjected to high energy particle irradiation is developed. Chemical reaction rate equations are used as a basis. Point defects, interstitials and vacancies, are assumed to be produced randomly throughout the solid. They move by random walk through the material until they cease to exist either by recombination with the opposite type of defect or by incorporation into the crystal at sinks such as dislocations, grain boundaries and voids. The rate equations for interstitials and for vacancies, which are coupled via the recombination term, are solved for steady state conditions under irradiation. Defect concentrations, supersaturations, recombination and total sink annihilation rates are obtained in terms of the production rate, sink annihilation probabilities, jump frequencies and thermal equilibrium concentrations of defects. The swelling rate is derived using sink annihilation probabilities at three principally different types of sinks, i.e. voids, sinks which have a bias with regard to the annihilation of interstitials and vacancies (such as dislocations), and sinks with no bias. The defect annihilation probabilities at void, precipitate, dislocation and grain boundary sinks are estimated by using a cellular model and solving the diffusion equation for geometries approximating that of the cells, e.g. a concentric sphere around a void. The relative effects of different types of sinks, i.e. the microstructure, on the swelling rate is discussed. The swelling rate is integrated to give swelling-time or swelling-dose relations, making some simplifying assumptions about the changes in the sink structure as the irradiation proceeds. It is shown that the relation obtained is rather sensitive to the type of assumptions made.

ISSN:0033-7579    

DOI:10.1080/00337577208231128

出版商:Taylor & Francis Group    

年代:1972

数据来源: Taylor

摘要:

A computer evaluation of a theory for co-precipitation of vacancies and solvent interstitials into voids is presented. Increasing the impingement frequency of interstitials (to up to 0.999 that of vacancies) severely curtails the nucleation process, by both elevating and widening the activation barrier. The critical nucleus size may be increased by several orders of magnitude, which in turn increases the incubation time so much that nucleation is suppressed for long periods of time, even though the steady-state rate is very great. The presence of interstitials has only a modest effect on the steady-state nucleation rate. Even at interstitial concentrations that have increased the critical size by orders of magnitude, the steady-state rate (usually exponential in critical nucleus size) is depressed by only a few powers of ten.

ISSN:0033-7579    

DOI:10.1080/00337577208231129

出版商:Taylor & Francis Group    

年代:1972

数据来源: Taylor

ISSN:0033-7579    

DOI:10.1080/00337577208231130

出版商:Taylor & Francis Group    

年代:1972

数据来源: Taylor

ISSN:0033-7579    

DOI:10.1080/00337577208231131

出版商:Taylor & Francis Group    

年代:1972

数据来源: Taylor

ISSN:0033-7579    

DOI:10.1080/00337577208231132

出版商:Taylor & Francis Group    

年代:1972

数据来源: Taylor