摘要:

The positron annihilation method (PA), Rutherford back scattering of channeled ions (RBSCI) and measurements of minority charge carrier lifetimes (MCCLT) combined have been used to investigate the processes of annealing and defect generation in semiconducting crystals affected by supercurrent electron beam (SEB). We used silicon samples phosphorous doped in the process of their growing (N≃1.7-1016cm−3), or boron doped(N≃2.3·xs1017cirr3) and implanted by phosphorous ions (D≃5.1014cm−2) of 30 keV energy as well as GaAs samples tellurium doped (N=2.6 1016cm−3) or implanted by Te ions (D≃3.1013cm−2and 1.2-1016cm−2) of 75 keV energy. Dependences of PA parameters andXminimum yield on the SEB energy density within the wide electron energy range have been obtained. The dependences have three regions: 1. Plateau when the beam effect cannot be detected by any of the methods used (the density being ⩽ 0.250 Joule/cm2for vacancy type defects and 0.4 Joule/cm2for interstitial atoms); (2) The annealing stage, which is characterized by decreasing the concentration of defects of both types (0.6-0.9 Joule/cm2); (3) Defect generation SEB induced (<0.9 Joule/cm2). It has been shown, that ionization-impurity and plasma-cumulative mechanisms of defect generation in semiconductors are the most probable ones. The first of them being a dominant one at low energy densities (1.0-2.0 Joule/cm2in Si), and the second at high energy densities (<2.0 Joule/cm2in Si)

ISSN:0033-7579    

DOI:10.1080/00337578508222542

出版商:Taylor & Francis Group    

年代:1985

数据来源: Taylor

摘要:

Aqueous solutions of uracil (U) were irradiated with Co-60 γ-rays in the presence of electron scavengers, e.g. nitrous oxide and nitrate. Analysis of the products was carried out by means of paper chromatography. In N2O saturated solution, the degradation of uracil has been ascribed to the intermediate formation of a hydroxyl adduct which it has been argued leads to products through an electron transfer process, and G(-U) was found to be equivalent to 0.5RwhereRcomprises H, eaq−and OH. The observed results have been compared with those reported earlier and the apparent anomalies have been rationalised in terms of a dose rate effect. NO3−ion has, however, been found to behave somewhat differently as an electron scavenger. The concentration of N03−was found to be a decisive factor in determining the course of radiolysis. Thus G(-U) is equivalent to ∼0.5 GRat low or zero nitrate concentration, ∼0.5 GOH over the range (0.5 – 3) × 10−3M and ∼GOH at higher concentrations.

ISSN:0033-7579    

DOI:10.1080/00337578508222543

出版商:Taylor & Francis Group    

年代:1985

数据来源: Taylor

摘要:

Internal friction and elastic modulus of dilute Al alloys have been measured after fast neutron irradiation at about 5 K. The internal friction spectra in Al-Pb, Al-Si, Al-Zn, Al-Ag, Al-Sn and Al-In are very similar. This result suggests that the configuration of the interstitial-solute atom complex in these alloys is very similar. In Al-Mg, the main complexes have the configuration with nearly <111> symmetry, but its internal friction spectrum is different from that of the above-mentioned alloys. The internal friction spectra and their annealing behavior in Al-Be, Al-Mn, Al-Fe and Al-Cu demonstrate that the configuration of their interstitial-solute atom complex seems to be different to each other and the main complex in these alloys is immobile until stage III.

ISSN:0033-7579    

DOI:10.1080/00337578508222544

出版商:Taylor & Francis Group    

年代:1985

数据来源: Taylor

摘要:

The oscillation component of the isothermal annealing curves of neutron irradiated crystalline tris-ethylenediamine cobalt (III) nitrate, magnesium and potassium chromate, isolated from various isotherms is presented in detailed form and studied kinetically. A temperature effect on the oscillation frequency and amplitude is also demonstrated. The experimental evidence strengthens the postulation for a possible solid state oscillation phenomenon independent of the chemical constitution of the lattice, due to thermodynamical conditions of irreversible processes. The Volterra-Lotka model is used for interpretation of the phenomenon.

ISSN:0033-7579    

DOI:10.1080/00337578508222545

出版商:Taylor & Francis Group    

年代:1985

数据来源: Taylor

摘要:

Mg+ions were implanted into (100) semi-insulating GaAs at room temperature with doses ranging from 5 × 1013to 1 × 1015/cm2with an energy of 100 keV. The samples were annealed using CVD Si3N4as an encapsulant at temperstures ranging from 700 to 950°C for times of 10 s and 30 s, using an incoherent light furnace. A maximum electrical activity of 98 % was obtained for a sample implanted to 5 × 1013/cm2and annealed at 900°C for 30 s. The depth profiles were found to be dose dependent and showed less redistribution than furnace anneals. A maximum hole concentration of about 3 × 1019/cm3was obtained for a dose of 1 × 1015/cm2annealed at 900 °C for 10 s.

ISSN:0033-7579    

DOI:10.1080/00337578508222546

出版商:Taylor & Francis Group    

年代:1985

数据来源: Taylor

摘要:

Magnetic disorder in neutron-irradiated (fission fragment damage) uranium mononitride (UN) has been investigated by magnetic susceptibility measurements. The Néel point (TN) shifted to lower temperatures with increasing fission dose and attained the lowest value at a dose of around 1018f/cm3. After further irradiations, however, it recovered to the non-irradiated value. The shift ofTNwas in accordance with the change of the concentration of fission-induced vacancies. Other magnetic parameters showed a similar trend. These fission-fragment damage results are discussed in terms of the electronic state of 5 f electrons.

ISSN:0033-7579    

DOI:10.1080/00337578508222547

出版商:Taylor & Francis Group    

年代:1985

数据来源: Taylor

摘要:

A simple model of amorphisation of metallic layers by high dose metallaid ion implantation is derived. It is assumed that covalent bonds are necessary to stabilise the amorphous state. Therefore, only a small fraction of the region damaged by an implanted metalloid ion may remain amorphised. This gives rise to higher amorphisation doses for ion implantation in metals than in semiconductors. Thermal relaxation during implantation and subsequent annealing is considered. Based on this model it is possible to understand the influence of the implanted ion dose on the recrystallisation temperature. For boron implantation in iron the amorphised volume per ion and the activation energy of the recrystallisation process are calculated. It is suggested that amorphous Fe1-xBxalloys produced by rapid quenching or ion implantation are very similar for boron concentrations higher than x=0.18.

ISSN:0033-7579    

DOI:10.1080/00337578508222548

出版商:Taylor & Francis Group    

年代:1985

数据来源: Taylor

摘要:

The irradiation of frozen methane by fast protons converts the methane molecules to a polymerlike residue that is stable at room temperature and above. This process is accompanied by a high preferential release of H2molecules with consequent lowering in the C:H stoichiometry. The chemical evolution of frozen methane at lowTand of the new organic material at roomT, is studied in this paper by quantitatively measuring the variations in the C:H ratio during 1.5 MeV proton fluence. Proton backscattering technique and 1R studies show that the ratio varies from C:H=1:4 in the originally deposited CHj to C:H - 1:0.5 after a total fluence ∼lE−17p (1.5 MeV) cm−2. The final product of the irradiation is then a carbon-like material with a little amount of methyl and methylene groups in it.

ISSN:0033-7579    

DOI:10.1080/00337578508222549

出版商:Taylor & Francis Group    

年代:1985

数据来源: Taylor

摘要:

Gamma irradiation of a simulated nuclear waste storage glass causes the formation of small bubbles in the glass by a process of network decomposition. This behavior is consistent with models previously proposed to account for electron damage in these same glasses. Comparison of the γ-irradiation effects with results of electron irradiations underscores the importance of ionization damage in the formation of microstructural defects and the importance of dose rate on the defect formation efficiency.

ISSN:0033-7579    

DOI:10.1080/00337578508222550

出版商:Taylor & Francis Group    

年代:1985

数据来源: Taylor

摘要:

Using recent experimental data on radiation induced surface segregation in non-homogeneous dilute metallic alloys at liquid nitrogen temperature, low temperature mechanisms of radiation induced segregation are discussed. The vacancy mechanism is ruled out at low temperature and the atomic solute transport which is controlled by interstitial diffusion is analyzed in its relationship to the solute/solvent size misfit. The analysis points to octahedral single solute interstitials as the entities responsible for solute transport and segregation in the case of oversized solutes. For undersized solutes the solute transport and segregation are probably due to “divacancy +solute atom”-point defects which are formed by reaction of substitutional solute atoms with neighboring vacancies. Solute/solvent chemical coupling which suppresses the radiation induced atomic transport is discussed and a criterion for its evaluation (solute/solvent bonding-enthalpy per solute atom) is proposed.

ISSN:0033-7579    

DOI:10.1080/00337578508222551

出版商:Taylor & Francis Group    

年代:1985

数据来源: Taylor