摘要:

Sequential irradiations and anneals were carried out on n- and p-type : α-tin filaments. Irradiations were performed at 4.5 K for a nominal electron beam energy of 0.90 MeV. A carrier removal rate varying with defect concentration was found. Isochronal anneals were carried out over the temperature range 20 to 47 K. Four first-order stages with activation energy scaling factors of 67, 90, 106 and 122 meV were resolved in order of increasing temperature. A fractional defect recovery scheme was deduced with defect concentration ratios given by IA: IB: IC: ID= 84:4:6:6 for the four stages. An average constant carrier removal rate was used to deduce charge carrier mobilities from both damage and annealing data. It was found that the electron mobilities were inconsistent with those deduced from the theory of ionized impurity scattering. A model is proposed requiring that the majority of the defects result in deep acceptor sites. In addition, shallow defect states positioned somewhat above the γ8* conduction and valence band junction are proposed to account qualitatively for the observed results.

ISSN:0033-7579    

DOI:10.1080/00337577508235382

出版商:Taylor & Francis Group    

年代:1975

数据来源: Taylor

摘要:

The volume change due to substitutional and interstitial helium atoms : n V, Fe, Mo, Ta, and W has been determined using the displacement fields from previously reported model calculations. Interstitial He produces a lattice expansion of less than one atomic volume in all metals studied, ranging from 0.4 to 0.9 Ω. The volume change for substitutional He in a given metal is 0.6 ± 0.1 Ω less than that for interstitial He in that same metal.

ISSN:0033-7579    

DOI:10.1080/00337577508235383

出版商:Taylor & Francis Group    

年代:1975

数据来源: Taylor

摘要:

Some questions of the amorphization mechanism of semiconductors during ion bombardment have been considered theoretically. The probability of the formation of crystalline disordered regions (CDR) and amorphous regions (AR)1has been calculated as a function of irradiation temperature T, atomic number Zi and ion enerw. It has been shown that the role of CDR in the amorphization process increases with the increase of T and decrease of Mi. The effect of irradiation temperature (T = −150, +25 and +1OO°C) on the silicon amorphization process during bombardment by light (B12), mean (Ne20) and heavy (Sb121) ions has been studied by various techniques: ir-absorption, ir-reflection and fast electron diffraction. It has been shown that the influence of irradiation temperature is stronger for light ions and large values ofT. Theoretical results are in good agreement with experimental ones.

ISSN:0033-7579    

DOI:10.1080/00337577508235384

出版商:Taylor & Francis Group    

年代:1975

数据来源: Taylor

摘要:

The validity range of the momentum approximation in binary collisions : s investigated. It is shown that at high energies,E≳ 10 ·Z1Z2e2/aTF, the approximation is even applicable to scattering angles ϑ as large as 60 degrees. An empirical formula for the evaluation of the momentum approximation employing the Thomas-Fermi-Moliére potential is given. It reduces the computer time to calculate ϑ to ∼⊥10of the time consumed in using the standard algebraic functions appearing in the momentum approximation.

ISSN:0033-7579    

DOI:10.1080/00337577508235385

出版商:Taylor & Francis Group    

年代:1975

数据来源: Taylor

摘要:

An experimental and theoretical treatment of the determination of : oron atoms in single crystalline silicon, using the channelling effect and flux peaking, is described.

ISSN:0033-7579    

DOI:10.1080/00337577508235386

出版商:Taylor & Francis Group    

年代:1975

数据来源: Taylor

摘要:

A “geometrical” model for the threshold cnergy surfaceof a b.c.c. lattice is applied to analyse recent measurements of the resistivity change rates in electron-irradiated monocrystalline molybdenum specimens with the orientations [100], [11O], [111] and [112]. Cross sections computed with this surface were matched to the experimental data using various sets of threshold energies as parameters. The best fit was obtained with Td [100] = (35+2−2) eV, Td [1101 > 2Td [100], Td [111] = (45 f 3) eV. When corn ared to the experimental damage rates the absolute values for the cross sections yield a Frenkel pair resistivity pio = (13 f 2) pfl cm/at.% F.P. Expressions for the energy necessary to penetrate the potential barriers in the principal crystallographic directions are derived and compared to the id[iik] obtained before, with the interatomic potential as parameter. Taking into account the length of the [111] collision chains and the size of the spontaneous recombination volume, the appropriate potential can be chosen in the range between UMo(r)/eV = 3000 exp(−3.2 r/A) and 11,000 exp(−3.8 r/A). An analysis of the displacement cross sections permitted to explain the energy and orientation dependence of stage I recovery and to attribute the sub-stages a t 15 K and 40 K to the annealing o f interstitials due to [100] displacements and the substages between 20 and 33 K to that of [111] chains of various lengths.

ISSN:0033-7579    

DOI:10.1080/00337577508235387

出版商:Taylor & Francis Group    

年代:1975

数据来源: Taylor

摘要:

The radiation induced degradation of five crystalline DL-amïno : cids, leucine, isoleucine, norleucine, valine, and norvaline, has been quantitatively studied. The major products are carboxylic acids formed by deamination of the amino acids, ammonia, amines formed by decarboxylation of the amino acids, and carbon dioxide. In addition, carbonyl compounds and amides, plus small amounts of hydrogen gas and various hydrocarbons have been detected. The total degradation, (−M), has been determined (by isotope dilution) to be 8 for valine and 14 for leucine.

ISSN:0033-7579    

DOI:10.1080/00337577508235388

出版商:Taylor & Francis Group    

年代:1975

数据来源: Taylor

摘要:

The γ-radiolysis of hydrogen sulphide in the presence of : utadiene and carbon tetrachloride was studied. Addition of butadiene causes the slow diminishing inG(H2) and sharp lowering inG(S) from 7.1 for pure H2S down to 0.8 at all the used concentrations of butadiene. When carbon tetrachloride is added to hydrogen sulphide,G(H2) is not changed butG(S) increases by ΔG(S) ≈ 2. The presence of butadiene and carbon tetrachloride together allows to the same change in G(H2) as in the case of butadiene alone and lowering I(S) to zero. The ionic mechanism of molecular sulphur formation is proposed, consistent with the observed experimental facts.

ISSN:0033-7579    

DOI:10.1080/00337577508235389

出版商:Taylor & Francis Group    

年代:1975

数据来源: Taylor

摘要:

The activation energy for migration of a divacancy in copper has been : alculated to be 0.47 eV in a pure copper lattice and 0.74 eV if the divacancy contains a helium atom. The result for the pure divacancy is in reasonable agreement with reported experimental values. The energy required for a helium atom to migrate from one vacancy to the other in a divacancy is found to be 0.18 eV so that the rate-limiting step in the migration of helium in copper via a divacancy mechanism is the movement of the divacancy at 0.74 eV.

ISSN:0033-7579    

DOI:10.1080/00337577508235390

出版商:Taylor & Francis Group    

年代:1975

数据来源: Taylor

摘要:

Electrochemically thinned and polished discs of high purity aluminium were irradiated with 60 keV argon ions and were subsequently examined in an energy analysing electron microscope of the Mollenstedt type. Image features believed to arise from small argon bubbles in the aluminium matrix and argon “blisters” at the aluminium/oxide interface were observed. The electron energy loss spectrum from the bubbles is in agreement with Natta's theory.

ISSN:0033-7579    

DOI:10.1080/00337577508235391

出版商:Taylor & Francis Group    

年代:1975

数据来源: Taylor