摘要:

40 keV Te ions were implanted in GaP at room temperature and measurements of the Ga and P disorder were made using the technique of Rutherford backscatteringof 1 MeV He+ions. The evaluation of the backscattering spectra for disordered binary crystals is discussed and shows that within the limits of sensitivity of the measurements, the degrees of disorder of both atomic species were equal. Attempts to anneal highly disordered crystals by either a 1 MeV He+probe beam or a 10 keV He+beam met with no success, both leading to enhanced damage.

ISSN:0033-7579    

DOI:10.1080/00337577208234687

出版商:Taylor & Francis Group    

年代:1972

数据来源: Taylor

摘要:

A method for determining energy losses from the spectrum of particles scattered by a thick target is presented. By this method the energy losses of protons in Pb, W, Ta, Yb, Ce, Ag, and Mo, and of α-particles to W have been determined. The results obtained agree with the data of other workers and with theory.

ISSN:0033-7579    

DOI:10.1080/00337577208234688

出版商:Taylor & Francis Group    

年代:1972

数据来源: Taylor

摘要:

Samples of low-alloy and low-carbon steels, and of α-iron containing 30, 70 and 270 ppm C were neutronirradiated at ambient temperatures, i.e. max 90°C for steels and max 40°C for α-iron. The doses varied from 5.5 × 1018to 3.5 × 1019neutrons/cm2. The mechanical properties were measured before and after irradiation and after post-irradiation annealing at temperatures up to 500°C. Maximum hardening was observed in steels after annealing between 100 and 250°C, and in α-iron, between 100 and 125°C. Using TEM the structure of nonirradiated, irradiated, anneal-hardened and recovered specimens was examined. It was concluded that radiation hardening, as well as anneal hardening was mainly due to invisible defects. The increase observed in the yield stress was found to be consistent with the hardening by dislocation loops of ∼20Å in diameter, which act as weak barriers.

ISSN:0033-7579    

DOI:10.1080/00337577208234689

出版商:Taylor & Francis Group    

年代:1972

数据来源: Taylor

摘要:

Enhanced diffusion of both diffused impurities andn+substrate impurities Sb and P in Si by proton irradiation is observed and analyzed in terms of steady state excess vacancy distribution. A simple Gaussian diffusion coefficient is employed for the analysis. The standard deviation of 1 μm or a little smaller for the Gaussian diffusion coefficient is reasonable for 300 to 450 kV proton irradiation at 900°C. The diffusion coefficients obtained for both diffused P and substrate P in the epitaxial wafer are not proportional to the proton beam density but show weaker dependence on it for more than 1 μA/cm2of proton beam density. It is concluded, from this fact, that the generated vacancy, which is effective to enhanced diffusion, annihilates not only by the first order annihilation process but also by the higher order process such as the vacancy-interstitial direct recombination.

ISSN:0033-7579    

DOI:10.1080/00337577208234690

出版商:Taylor & Francis Group    

年代:1972

数据来源: Taylor

摘要:

The electron spin resonance spectra of some irradiated aliphatic amino acids and dipeptides have been observed and quantitative measurement obtained of their free radical yields. The yields, ESR spectra and stabilities have been explained in terms of their crystal structure.

ISSN:0033-7579    

DOI:10.1080/00337577208234691

出版商:Taylor & Francis Group    

年代:1972

数据来源: Taylor

摘要:

Hall effect and resistivity measurements have been made on undopedn-type and Cd-dopedp-type GaAs crystals irradiated with electrons at 287°K. For 1 MeV irradiations, the dose dependence of carrier removal and mobility inn-type suggests that a defect energy level atEc-0.1±0.015 eV was introduced by irradiation and was the upper level of a doubly charged acceptor. A donor level was also found inn-type at approximatelyEc− 0.20 eV, and deeper acceptor levels were also introduced. Inp-type a similar study located a radiation introduced level atEv+0.1 ± 0.015 eV, which could be a singly or doubly ionized donor.

ISSN:0033-7579    

DOI:10.1080/00337577208234692

出版商:Taylor & Francis Group    

年代:1972

数据来源: Taylor

摘要:

Helium ions of 275 keV have been scattered at glancing angles from the flat {110} surface of a tungsten single crystal. The angular distribution of the scattered particles in the plane of incidence was measured, as well as their energy spectrum. The energy spectrum had the shape of a skewed peak, and its low-energy tail became more pronounced when a low index direction lay in the surface in the scattering plane. This is ascribed to channelling of the projectiles in the surface. The angular distribution of the scattered particles shows roughly specular reflection behaviour, and it is shown that this is expected whenever the surface may be described as an array of continuum potentials, in which transverse energy is conserved. The scattering of the helium is influenced by the structure of the surface, and it is shown that most of the particles observed have been scattered from the second atomic layer of the surface into the detector. The most probable energy loss of the scattered particles decreases with increasing scattering angle. The relationship of the experiment to conventional channelling experiments is discussed, and it is concluded that it may yield extra information about the channelling process.

ISSN:0033-7579    

DOI:10.1080/00337577208234693

出版商:Taylor & Francis Group    

年代:1972

数据来源: Taylor

摘要:

Light emission from a 60 keV He+beam excited by an 80Å thick single crystal gold film has been measured. The line intensity was monitored as function of crystal orientation (parallel and near to the ⟨100⟩ string). To avoid the influences of forward scattering a special experimental arrangement was devised. The results demonstrate that there is little, if any, effect of channelling in single crystal beam foil spectroscopy.

ISSN:0033-7579    

DOI:10.1080/00337577208234694

出版商:Taylor & Francis Group    

年代:1972

数据来源: Taylor

摘要:

Samples of α-tin were bombarded at liquid helium temperatures by electrons in the energy range 0.5 to 1.0 MeV. Large changes in the D.C. resistance were observed. From the energy dependence of the damage rate, a threshold displacement energy of 12±1 eV was deduced, and the shape of the damage rate vs. energy curve indicated that Frenkel pair defects were introduced. Isochronal annealing resulted in three distinct annealing stages in the temperature range 20–50K. Tentative activation energies for the stages were 0.06–0.115 eV, depending upon the assumed order of kinetics. There is evidence that the recovery is due to electronic transitions between the L6,T8and one or more extrinsic energy levels.

ISSN:0033-7579    

DOI:10.1080/00337577208234695

出版商:Taylor & Francis Group    

年代:1972

数据来源: Taylor

摘要:

Transmission electron microscopy and immersion density techniques were used to characterize the nature and extent of radiation damage in zone refined and commercial purity magnesium irradiated to 1.7 × 1021neutrons/cm2(>0.1 MeV) at about 75°C. Swelling from radiation-induced voids was 1.9 and 0.7 per cent, respectively, for the high purity and commercial magnesium. This difference was caused by larger voids in the zone refined material. The voids had a non-equiaxed shape, being bounded by {0001}, {1010}, and {1011} and were flattened in ⟨0001⟩, but the larger voids were more equiaxed. There was pronounced clustering of voids on {0001} planes. The irradiation-induced dislocation structure was also clustered on the basal planes. This dislocation structure is deduced to consist of a complex tangle of 1/2 ⟨2023⟩ partial dislocations and their associated stacking faults.

ISSN:0033-7579    

DOI:10.1080/00337577208234696

出版商:Taylor & Francis Group    

年代:1972

数据来源: Taylor