摘要:

The effect of the gas background in argon glow discharges on the structure of sputtered tantalum films has been studied. The films were deposited in a 240‐liter chamber of a conventional oil‐diffusion pump system, and in 2‐liter chambers of two sputter‐ion ultrahigh‐vacuum systems. Initial vacua before static sputtering ranged from 1.5×10−10Torr to 2×10−7Torr. The gas background generated by the desorption effect of the glow discharge was minimized by presputtering periods of varying duration. The films were found to be mostly beta tantalum, with varying contents of bcc tantalum. The results indicate that the appearance of beta tantalum depends on the substrate temperature, and that the formation of beta tantalum and its resistivity are independent of the gas‐background impurities in deposition systems with ultimate pressures between ∼10−10and ∼10−7Torr.

ISSN:0021-8979    

DOI:10.1063/1.1710059

出版商:AIP    

年代:1967

数据来源: AIP

摘要:

The optical constants of nine compounds of NiAl ranging in composition from 45.2 at.% Ni to 61.6 at.% Ni have been determined between 0.212 and 1.80 &mgr;. Measurements of the ratio of the reflectance of light polarized parallel to the plane of incidence to the reflectance of light polarized perpendicular to the plane of incidence were made at the following five angles of incidence: 55°, 60°, 65°, 70°, 75°. Data were analyzed by a computerized interation technique to provide values of the high‐frequency dielectric constants and the electrical conductivity. Since the measurements were made on mechanically polished surfaces, two annealing experiments were performed to ascertain the effects of surface disturbance; the results showed that the optical properties were essentially unaffected by the annealing treatments. Plots of 2nkshow absorption bands at ≈1.5 to 2, 2.5, 4.0, and 5.1 eV and what may be interpreted as free‐electron behavior below 1.5 eV. The energy‐band structure shows a strong compositional dependence which has been interpreted to be the result of contact between the Fermi surface and a Brillouin‐zone boundary.

ISSN:0021-8979    

DOI:10.1063/1.1710060

出版商:AIP    

年代:1967

数据来源: AIP

摘要:

Measurements of the effects of60Co &ggr;‐ray irradiation have been made upon the dislocation internal friction and modulus defect in copper single crystals from 333° to 393°K. It is found that the number of pinning points which are nucleated on the in‐grown dislocations by the lattice defects produced by the irradiation depends upon the &ggr;‐ray flux, or more directly, upon the concentration of defects in the dislocation core. At the smallest flux level available (1.3×109photons/cm2/sec), it is found that the dislocation‐defect trapping curves are essentially linear, and that the slopes of the linear curves vary exponentially with temperature. These results form the basis of the analyses given in Parts II and III of this series.

ISSN:0021-8979    

DOI:10.1063/1.1710061

出版商:AIP    

年代:1967

数据来源: AIP

摘要:

Using the experimental results given in Part I as a guide, a linear model is developed in this Part which describes the interaction of a lattice defect and a dislocation. It is supposed in this model that the defect is free to diffuse between existing (or in‐grown) traps such as jogs or dislocation nodal points, and that if the defect is trapped, dislocation climb follows. From a comparison of the results given in Part I and the predictions of the model, values for the ``pipeline'' diffusivity and the strength of the binding of the defects to the in‐grown nodal points may be obtained. The numbers so obtained are consistent with values evolved from other techniques for studying atom motions. An estimate for diffusional jog‐pair energies is also given.

ISSN:0021-8979    

DOI:10.1063/1.1710062

出版商:AIP    

年代:1967

数据来源: AIP

摘要:

An analysis of the bulk diffusion properties of the stage‐III defect is given utilizing the experimental results presented in Part I. It is found that the motion energy of the defect is 0.64±0.03 eV and, in addition, it is shown that this is a true motion energy and not a defect‐impurity‐atom binding energy. After consideration of the extremely small lattice‐defect concentrations used (≤10−12), available information concerning single‐vacancy motion energies, and the simple‐defect spectrum produced by the &ggr; irradiation, it is concluded that the stage‐III defect can only be identified as a freely migrating interstitial atom.

ISSN:0021-8979    

DOI:10.1063/1.1710064

出版商:AIP    

年代:1967

数据来源: AIP

摘要:

The thermal diffusivity of five platinum samples with resistivity ratios of 12, 34, 100, 900, and 5000 has been measured from 300° to 1200°K. Only the sample with the resistivity ratio of 12 showed deviations of more than 3% from the average thermal diffusivity of the two purest samples. Thermal conductivity values have been calculated from these results and compared with the results of other investigators. At room temperature most results are in good agreement, but at high temperatures the agreement among different investigators is unsatisfactory. The data from our purest samples indicate that platinum would be suitable for a thermal conductivity standard, but additional measurements should be made by other absolute methods.

ISSN:0021-8979    

DOI:10.1063/1.1710065

出版商:AIP    

年代:1967

数据来源: AIP

摘要:

The crystal structure of ZnS single crystals grown from melt has been found to be cubic zinc blende by the x‐ray analysis of oscillation photographs. However, the x‐ray ⟨111⟩ axis oscillation patterns of the crystals synthesized by various methods are symmetric about the equator line and some spots are elongated alongc*, whereas the patterns of natural crystals are asymmetric and sharp. Therefore, it is concluded that the synthetic ZnS crystal contains a considerable amount of stacking disorder in the close‐packed planes due to growth faults which result in two orientations in the crystal structure (twin orientations) that repeat with a relatively short periodicity. The value of fault probability occurring in the (111) plane can be obtained by superimposing the observed diffuse diffraction spectra with the ones calculated numerically by a formula proposed by Paterson for the growth fault. This value is also compared with that obtained from the transmission electron micrographs.

ISSN:0021-8979    

DOI:10.1063/1.1710066

出版商:AIP    

年代:1967

数据来源: AIP

摘要:

The yield behavior of dislocation‐free germanium has been measured over its entire plastic range. Crystals of germanium were stressed in tension from 500°C, where the crystals first deform without fracture, to 930°C (7°C below the melting point). Over this entire range a pronounced yield drop is observed. The shapes of the stress‐strain curves at the highest and lowest test temperatures are remarkably similar even though the magnitudes differ by about a factor of 40. Both the maximum and flow stresses decrease exponentially with temperature and follow a relation of the form &tgr; =Aexp (E/kT). The maximum and flow stresses also were measured at constant temperature over two orders of magnitude change in strain rate. The results are compared with the theoretical predictions of the temperature and strain‐rate dependence of the maximum and flow stresses.

ISSN:0021-8979    

DOI:10.1063/1.1710067

出版商:AIP    

年代:1967

数据来源: AIP

摘要:

Evaporated metallic contacts (area = 0.1 mm2) have been made to etched (100) surfaces of conducting strontium titanate single crystals. The metals employed were Mg, In, Au, Pd, and Pt. The electrical properties of these contacts were studied by measurements of: (1) differential capacitance as a function of bias voltage, (2) spectral variation of photoemission from the metal into the strontium titanate, and (3) current‐voltage characteristics. The measurements have been analyzed to yield effective values of &Dgr;&phgr; (work function of the metal with respect to the strontium titanate conduction band at the contact) with the following results: (1) the electrical properties of the contacts are different for the different metals, (2) the low‐work‐function metals (Mg and In) form low‐resistance contacts, (3) the high‐work‐function metals (Au, Pd, and Pt) form blocking contacts, and (4) none of the blocking contacts can be characterized by a single value of &Dgr;&phgr;; i.e., each blocking contact behaves as if it consists of patches of different &Dgr;&phgr;.

ISSN:0021-8979    

DOI:10.1063/1.1710068

出版商:AIP    

年代:1967

数据来源: AIP

摘要:

The efficiency, negative resistance, and conditions for space‐charge control relevant to operation of a bulk semiconductor diode in the limited space‐charge accumulation (LSA) mode of oscillation are discussed. Numerical results forn‐GaAs indicate a maximum dc to rf‐conversion efficiency of 18.5% for sine‐wave excitation. The usable range of doping to frequency forn‐GaAs is found to be 2×104to 2×105sec/cm3with an optimum value of about 6×104sec/cm3. Although a reduction in efficiency at frequencies above 100 GHz is expected due to the finite response time of GaAs, worthwhile efficiency may be obtained at several hundred GHz.

ISSN:0021-8979    

DOI:10.1063/1.1710069

出版商:AIP    

年代:1967

数据来源: AIP