摘要:

We present the results of a crystallization study in glassy Ni‐Zr. The alloys were prepared by melt spinning over the continuous range Ni20Zr80to Ni70Zr30including for the first time the region between Ni40Zr60and Ni60Zr40. As expected we find that the glasses are most stable at and around the eutectic compositions, except that at the extreme Zr‐rich eutectic the glasses are destabilized by the premature precipitation of &ohgr;‐Zr. The products of crystallization indicate that the current crystalline phase diagram is incomplete: a new peritectoid phase must be added at the composition Ni2Zr.

ISSN:0021-8979    

DOI:10.1063/1.332465

出版商:AIP    

年代:1983

数据来源: AIP

摘要:

The generation rate of paramagnetic defects has been measured by means of Electron Paramagnetic Resonance over the 1015–1017‐10n  cm−2fluence range, using a low flux (7×101010n  cm−2 s−1) of fast neutrons; much higher yields are achievable than reported up to now. A comparison of 4.2‐  and 295‐K spectra evidences a narrowing of the hyperfine structure separation of the components of the AsGaquadruplet with increasing temperature.

ISSN:0021-8979    

DOI:10.1063/1.332466

出版商:AIP    

年代:1983

数据来源: AIP

摘要:

S‐implanted GaAs at room temperature was annealed by several seconds radiation from halogen lamps. Differential Hall effect/sheet resistivity measurements have been used to study the annealing behavior and electrical carrier concentration profiles of S‐implanted GaAs. Electrical activation was found to increase with increasing annealing temperature up to 1100 °C. A maximum electrical activation of 78% was obtained for a dose of 5×1013cm−2. Also, more than 5×1018cm−3peak carrier concentration was obtained for a dose of 1×1014cm−2, indicating about three times higher peak concentration than that obtained after conventional furnace annealing. For higher doses, the implanted S in the annealed GaAs does not follow Gaussian distribution even after rapid annealing. Damage‐enhanced outdiffusion of S is considered to be responsible for this result.

ISSN:0021-8979    

DOI:10.1063/1.332467

出版商:AIP    

年代:1983

数据来源: AIP

摘要:

Infrared reflection and transmission measurements of GaAs implanted with large fluences of Be ions have been made as a function of post‐implantation annealing temperature. Annealing up to 400 °C resulted in decreases in the lattice disorder responsible for changes in the dielectric constant. This decrease appears to take place uniformly throughout the disordered layer rather than by an epitaxial process. Annealing at 400 °C for 2 h returns the dielectric constant to essentially the preimplantation value with no significant carrier activation being observed. Carrier activation is observed only after prolonged annealing at 400 °C, i.e., ≳50 h. Annealing for 1 h at 450 °C also produces measurable carrier activation. These results are in general accord with prior electrical data and transmission electron microscope measurements and suggest that the removal of the disorder‐induced changes in the dielectric constant and the activation of free carriers might involve different annealing processes.

ISSN:0021-8979    

DOI:10.1063/1.332468

出版商:AIP    

年代:1983

数据来源: AIP

摘要:

The structural and compositional changes in ion‐implanted and annealed Hg1−xCdxTe (x=0.21; 0.29) were studied by means of ion‐beam probing techniques. Rutherford backscattering (RBS) and particle‐induced x‐ray (PIXE) experiments were carried out under channeling the nonchanneling conditions. The following results were found. (i) The damage caused by room‐temperature implantation of a variety of ions (Al, P, Ar, In, Hg) reaches saturation when an energy density of 2–4×1024eV/cm3goes into nuclear collisions. (ii) The damage profile for light ion implantation (150‐keV, P, Ar) is more shallow than the implant range, while for heavy implants (300‐keV, In, Hg) it extends substantially deeper than the range. (iii) The damage consists of extended defects, probably stacking faults. The results of furnace,Q‐switched ruby, and cw CO2laser annealing were investigated. Best annealing was obtained when the implanted surface was irradiated with photons from a cw CO2laser for 0.3 sec at a power of 250 W/cm2. Under such conditions the crystallinity is restored and no changes in stoichiometry are evident. The theoretical considerations for the choice of RBS or PIXE analyses for compound crystals are reviewed.

ISSN:0021-8979    

DOI:10.1063/1.332469

出版商:AIP    

年代:1983

数据来源: AIP

摘要:

The energy spectra, angular distributions, and the absolute quantum efficiencies of forward emission electrons from60Co &ggr;‐ray irradiated metallic elements have been measured using a double focusing &bgr;‐ray spectrometer. Samples measured were C, Al, Cu, Mo, Sn, W, and Pb. Their thicknesses were chosen about equal to the maximum range of a 1.33 Mev photoelectron so as to ensure electron equilibrium. Similar spectral shapes were observed for samples with similar atomic numbers, but energy spectrum for the large atomic number sample was different from the small atomic number one. Photoelectron peaks were observed in the spectra for W and Pb. An empirical equation which gives the quantum efficiency as the function of atomic number was obtained. The efficiencies computed from this equation were in good agreement with experimental results and numerical calculations.

ISSN:0021-8979    

DOI:10.1063/1.332470

出版商:AIP    

年代:1983

数据来源: AIP

摘要:

Polymer films darken upon irradiation with energetic ion beams. At high doses (1016–1017cm−2) of 2‐MeV Ar+ions, the resistivity of these insulating films decreases dramatically to 3.5×10−3&OHgr; cm. Furthermore, over a wide range of doses (1014–1015cm−2) these films exhibit a temperature‐dependent resistivity characteristic of carrier transport via hopping between isolated conducting islands. Rutherford backscattering measurements indicate that while a substantial amount of the carbon is retained in the film, other constituent elements are lost. Raman spectra show that the films are highly disordered at large ion doses.

ISSN:0021-8979    

DOI:10.1063/1.332471

出版商:AIP    

年代:1983

数据来源: AIP

摘要:

The theoretical problem of the electric response of biased dielectrics and piezoelectrics subjected to planar stress pulse loading is considered. The materials are taken to exhibit dielectric relaxation in the sense that changes in the polarization induced by electric fields do not occur instantaneously with changes in the fields. While this paper considers arbitrary stress pulse loading of the specimen, examples that are amenable to projectile impact techniques are considered in detail. They are shock reverberation, thin pulse, and ramp loading experiments. It is anticipated that these experiments will play a role in investigations of dielectric relaxation caused by shock induced damage in insulators.

ISSN:0021-8979    

DOI:10.1063/1.332472

出版商:AIP    

年代:1983

数据来源: AIP

摘要:

The relationship between incipient stress‐pulse‐induced damage and the electrical response of a piezoelectric, ferroelectric, or electrically biased dielectric is examined. The model assumes the presence of isolated inclusions of damaged material which are conducting and which may grow. Virgin insulating material surrounds the inclusion . Sillars’ model of an inhomogeneous dielectric is invoked to yield parameters of an electrically equivalent, relaxing dielectric. These parameters are used to generate the electrical response caused by propagating stress pulses. Qualitative agreement with current histories obtained from experiments onX‐cut quartz is obtained, quantitative results await further experimentation.

ISSN:0021-8979    

DOI:10.1063/1.332473

出版商:AIP    

年代:1983

数据来源: AIP

摘要:

The temperature dependence of the nonlinearity constant in pure silicon and germanium have been studied for longitudinal waves along the ⟨100⟩ axis in the temperature range 73–293 K. The estimated temperature dependence has been compared with that obtained from the experimental values of attenuation. Attenuation of 480 and 286 MHz ultrasonic waves for silicon and of 306 MHz ultrasonic waves for germanium have been evaluated, using a temperature dependent nonlinearity constantD, and compared with experimental values of attenuation available in the literature. The results are found to be in good agreement with the experimental values for silicon and germanium.

ISSN:0021-8979    

DOI:10.1063/1.332474

出版商:AIP    

年代:1983

数据来源: AIP