摘要:

The variation of the fixed oxide charge and the surface state densiy concentration are investigated in MOS structures under γ-irradiation from a60Co source. SiO2in the studied samples was obtained in a planar plasma reactor at low temperature (300°C) from three different gaseous mixtures: (i) SiH4+ N2O; (ii) (C2H5O)4Si + O2; (iii) SiCl4+ O2. Standard samples with high-temperature Si02, obtained through oxidization in dry O2with and without chlorine vapours were simultaneously studied for comparison. It was established that the samples obtained through the SiCl4+ 02reaction showed the best radiation stability.

ISSN:0033-7579    

DOI:10.1080/00337578208235404

出版商:Taylor & Francis Group    

年代:1982

数据来源: Taylor

摘要:

The ratioRof the intensities of the single and double scattering peaks observed in Ion Scattering Spectroscopy has been determined as a function of several experimental parameters. If all particles scattered through a certain scattering angle are detected with a time of flight spectrometer or when alkali ions are used as primary particles then the absolute value ofRas well as the dependence on the experimental parameters correspond with the results of several theoretical models. A simple two atom model, using the Thomas-Fermi-Molière potential, yields very satisfying results. For low index directions on the surfaceRis a straightforward measure for the interatomic distance of neighbour surface atoms. For high index directions surface zig-zag collisions complicate the interpretation, but the shape of the energy spectra can be understood reasonably well. When noble gas ions are used as primary particles and only the scattered ions are detected,R+ is influenced by charge exchange and neutralization processes, which complicate the interpretation, and the dependence ofR+ on the experimental parameters does not agree with theoretical expectations forR.

ISSN:0033-7579    

DOI:10.1080/00337578208235405

出版商:Taylor & Francis Group    

年代:1982

数据来源: Taylor

摘要:

Crystalline quartz samples, irradiated with fast neutrons are studied with positron annihilation techniques. The results confirm that the amorphization process induced by the irradiation leads, at saturation doses (øt=1020 n/cm2), to a physical state which is different from the one in vitreous silica. The behaviour of the positron annihilation pick-off lifetime and intensity in the irradiated material can be understood on the basis of a spikelike mechanism for the amorphization process.

ISSN:0033-7579    

DOI:10.1080/00337578208235406

出版商:Taylor & Francis Group    

年代:1982

数据来源: Taylor

摘要:

Radiation damage induced by fission fragments has been studied qualitatively, mainly by powder X-ray diffraction, in several crystalline phases which might occur in radioactive waste solidified by ceramic methods. The phases were synthesized by ceramic techniques and contained depleted or enriched uranium. Reactor irradiation induced fission fragment damage.

ISSN:0033-7579    

DOI:10.1080/00337578208235407

出版商:Taylor & Francis Group    

年代:1982

数据来源: Taylor

摘要:

The depth dependence of microstructural damage and swelling in pure nickel during nickel-ion bombardment at 0.51Tmis measured and is compared with the predictions of the E-DEP-1 code. Cavities are developed to depths 30 to 40° greater than the maximum depths calculated for a significant level of displacement events. It is argued that diffusional spreading of point defects contributes to this extension. A helium distribution superimposed on the heavy ion damage profile greatly increases nucleation of cavities and reduces their growth. The swelling profile is modified in a complex manner by the local concentration of helium and by the method of implanting it. In general, helium preimplanted at room temperature strongly over-stimulates cavity formation causing enhanced swelling at low heavy ion dose and depressed swelling at high dose. Helium implanted simultaneously with heavy ion damage gives more gradual promotion of cavities and continuously increasing swelling with dose. A band of deep dislocations is found at twice the predicted maximum depth for damage, and is attributed to relief of the nonuniform swelling by plastic deformation.

ISSN:0033-7579    

DOI:10.1080/00337578208235408

出版商:Taylor & Francis Group    

年代:1982

数据来源: Taylor

摘要:

Low dimensional conductors are solids with very anisotropic transport properties either one or two dimensional. Metals of chains or layers at high temperatures, they are, at low temperatures, either insulators or superconductors because of instabilities of the electron gas responses related to their low dimensionality. The very anisotropic transport properties of these rather new compounds were demonstrated to be important simplifying factors in the studies of disorder and defects in these structures, specially in the determination of the defect concentrations. Radiation damage experiments on this kind of solids have, in turn, provided interesting and original answers to more general radiation effects problems, even leading to a possible application of some of these conductors to Γ-rays and fast neutrons dosimetry. A part of these conductors are organic molecular crystals. The mechanisms of damage production have been explored in some of them and it has been shown that damage rates (g) under X-rays, Γ-rays or electron irradiations can be determined in these conductors even more accurately than in normal molecular crystals. The volume of the average irradiation defect has been determined in one of these molecular conducting solids (TTF-TCNQ). In inorganic low dimensional conductors either lamellar, or one-dimensional, it has been possible to determine rather accurately the concentration of Frenkel pairs produced by electron irradiation and to have a reasonable idea of the location of the self interstitials in the structure. Investigations on the low-temperature phases of these crystals have produced a number of new results about metal-to-insulator and metal-to-superconductor phase transitions in presence of irradiation defects.

ISSN:0033-7579    

DOI:10.1080/00337578208235409

出版商:Taylor & Francis Group    

年代:1982

数据来源: Taylor

摘要:

The van der Pauw technique has been used to make measurements of the electrical resistance, Hall mobility and carrier concentration of ion-implanted lead telluride at 77 K. Small changes in the electrical properties were observed for relatively large changes in the implantation parameters. A previously unreported room temperature annealing process was found to produce large increases in carrier concentration in samples bombarded with protons of low energy (∼50 keV). This annealing effect appears to be due to the loss of lead vacancies by migration out of the bombarded region to either the surface or the bulk of the sample.

ISSN:0033-7579    

DOI:10.1080/00337578208235410

出版商:Taylor & Francis Group    

年代:1982

数据来源: Taylor

摘要:

The channeling radiation with the account of the energy zone structure is investigated. Three types of radiation transitions are considered: within the potential well; from the above-barrier zones into the well; between the above-barrier zones. The first type is the Kumakhov radiati on. It is shown that the latter is more intensive than the radiation of the other two types by an order. This ratio increases under the effect of the electron beam divergency. A detailed comparison with the coherent Bremsstrahlung have shown that neither type of radiation transitions at channeling can be described by means of the coherent Bremsstrahlung theory. The dependence of the population on the electron incidence angle with respect to the atomic plane and beam divergency is investigated. At optimum incidence angles it is possible to obtain the inverse population,i.e.the induced radiation.

ISSN:0033-7579    

DOI:10.1080/00337578208235411

出版商:Taylor & Francis Group    

年代:1982

数据来源: Taylor

摘要:

Powerful ion pulses are shown to cause creation of defects in single silicon crystals. RBS measurements demonstrated that the width of defects distribution is much larger than distribution of implanted atoms. There has been noticeable annealing of defects in crystals by the action of ion pulses and migration of the single defects in crystal channels.

ISSN:0033-7579    

DOI:10.1080/00337578208235412

出版商:Taylor & Francis Group    

年代:1982

数据来源: Taylor

摘要:

The one-dimensional forward-backward model of Fermi for the scattering of identical particles is generalized to a pseudo-two-dimensional model with three possible travelling directions. The proposed model is apt to account for the correlation between the scattering angle and the post-collision energy. The collision density in a homogeneous half-space, due to monoenergetic isotropic surface source, is determined analytically in the Laplace domain (with respect to the lethargy) assuming hard-sphere scattering, and the radiation-damage related quantities are expressed in the Kinchin-Pease damage model. Numerical values of the defect distributions, sputtering spectrum and spatial moments of the collision density are compared to exact Monte Carlo results and the comparison shows good agreement. Numerical results demonstrate that the model is superior to both the forward-backward model and theP1 approximation.

ISSN:0033-7579    

DOI:10.1080/00337578208235413

出版商:Taylor & Francis Group    

年代:1982

数据来源: Taylor