摘要:

Silicon‐metal systems are highly susceptible to solid‐solid reactions which modify their electrical and mechanical properties. Although many works are dealing with silicide formation, the molybdenum‐silicon system has not yet been investigated in detail to our knowledge. In this paper we present a He+ion backscattering study of the molybdenum‐silicide formation by interaction of a thin molybdenum layer and a silicon ⟨111⟩ wafer. The silicide phases Mo3Si and MoSi2have been identified by x‐ray diffraction and transmission electron microscopy. Surface transformations were observed by scanning electron microscopy. For an 800‐A˚ Mo layer sputter deposited on silicon, we have found a time‐square growth rate for MoSi2with an average activation energy of 2.4 eV in the temperature range 475–550 °C. The fundamental roles of the cleaning of the silicon surface, of the substrate temperature during sputtering, and of the stresses in the layer are pointed out.

ISSN:0021-8979    

DOI:10.1063/1.324337

出版商:AIP    

年代:1978

数据来源: AIP

摘要:

A direct quantitative measurement of cesium adsorbed into polycrystalline tantalum has been made by a new technique involving radioactive cesium. Cesium vapor was admitted into a known control volume and adsorbed onto two adjacent parallel tantalum disk faces. The amount of adsorbed radioactive cesium was monitored with a sodium iodide crystal &ggr; detector. The surface and cesium reservoir temperatures were independently controlled. Tantalum surface temperatures of 500–1700 °K and cesium arrival rates of 1015–1021atoms/cm2have been investigated. Atom concentration is plotted as a function of temperature for various constant cesium arrival rates. The results follow theoretical predictions up to 0.5–0.75&percent; of a monolayer. At higher coverages, the cesium adsorption increases rapidly to well over one monolayer. The cause of this rapid increase is determined to be the formation of cesium oxide on the surfaces resulting from a calculable diffusion of oxygen through the tantalum test chamber. Although the oxygen content is not measured, the qualitative behavior of the Cs‐O system is shown. Surfaces with coadsorbed cesium and oxygen have a particular usefulness in improving performance of thermionic energy converters.

ISSN:0021-8979    

DOI:10.1063/1.324342

出版商:AIP    

年代:1978

数据来源: AIP

摘要:

Defect structures inn‐type (001) and (1¯1¯1¯) homoepitaxial layers, grown by liquid phase epitaxy (LPE) onp‐type InP substrates, have been evaluated by transmission electron microscopy. It is shown that, even under ideal conditions of lattice match, defect structures are observed in epilayers. The (001) layer exhibits slip structure consisting of screw dislocations. It is argued that this structure could not have evolved to accommodate either the lattice parameter difference or twist that may have been inadvertently introduced during LPE. On the other hand, the (1¯1¯1¯) layer shows isolated faults and fault clusters consisting predominantly of intrinsic faults.

ISSN:0021-8979    

DOI:10.1063/1.324338

出版商:AIP    

年代:1978

数据来源: AIP

摘要:

Internal friction of vacuum‐deposited silver films 2–4 &mgr;m thick was measured using the vibrating‐reed method below room temperature in the frequency range 100–400 Hz. Two distinct relaxation peaks were observed, one at around 50 K and the other at around 140 K. The former has been identified as the Bordoni peak, which was very stable against annealing at temperatures as high as 500 °C. The latter is considered as one of the Hasiguti peaks, which completely disappeared through annealing at 400 °C.

ISSN:0021-8979    

DOI:10.1063/1.324373

出版商:AIP    

年代:1978

数据来源: AIP

摘要:

We present a Green’s function theory of the nonlinear interaction of surface polaritons propagating along the plane interface between vacuum and a noncentrosymmetric dielectric medium. These nonlinear effects are induced by the nonlinear polarization of the dielectric medium. The nonlinear effects considered are second harmonic generation of a surface polariton, the nonlinear mixing of two surface polaritons, and optical rectification of a surface polariton. Numerical estimates for the magnitudes of these effects are presented for GaAs, for which the necessary second‐order susceptibilities in the infrared have been determined.

ISSN:0021-8979    

DOI:10.1063/1.324375

出版商:AIP    

年代:1978

数据来源: AIP

摘要:

A method of liquid‐phase epitaxial growth of smooth thin layers on nominally oriented GaAs substrates is described. It utilizes a rapid etch‐back of the substrate by an undersaturated solution, followed by growth from the same solution as it cools. The technique overcomes the requirement of an exactly oriented substrate for growth of smooth layers, and simultaneously produces a clean interface between the epi‐layer and the substrate.

ISSN:0021-8979    

DOI:10.1063/1.324376

出版商:AIP    

年代:1978

数据来源: AIP

摘要:

The photoelectronic properties of liquid‐phase epitaxial GaAs : Cu, either grown from a Ga melt with Cu impurity added or with incorporation of Cu by diffusion after growth, have been investigated through measurements of photocapacitance; conductivity in light and dark as a function of photon energy, light intensity, and temperature; thermal and optical quenching of photoconductivity; thermally stimulated conductivity; and photoluminescence. When Cu is present in the growth melt, the electron density in the resulting LPE GaAs layer is increased; when Cu is diffused into a grown layer, it behaves as a conventional acceptor and converts the layers to high‐resistivityp‐type conductivity. A Cu‐related center with energy level about 0.43 eV above the valence band, electron‐capture cross section of 10−21cm2, and hole‐capture cross section of 10−16cm2is observed in the layers produced with Cu in the melt by spectral response of photocapacitance and photocapacitance decay, and in the layers with diffused Cu by thermal and optical quenching of photoconductivity, spectral response of photoconductivity, and thermally stimulated conductivity. Six other levels, three of them electron traps and three of them hole traps, are also observed and described.

ISSN:0021-8979    

DOI:10.1063/1.324377

出版商:AIP    

年代:1978

数据来源: AIP

摘要:

Using the Mo¨ssbauer technique, we have measured the electric quadrupole and magnetic dipole hyperfine interaction of61Ni in NiCr2O4. The magnetic transition temperature and the saturation magnetic hyperfine field were determined to be 69±2 K and 442±3 kOe, respectively. The temperature dependence of the reduced field can be reproduced by a Brillouin function withS=1. With the onset of the magnetic ordering, the electric quadrupole interaction parameter changes by a factor of about −2, which indicates that the spin of the Ni2+ion is parallel to the [a,b] plane of the crystal.

ISSN:0021-8979    

DOI:10.1063/1.324378

出版商:AIP    

年代:1978

数据来源: AIP

摘要:

By means of potential discharge techniques, hole transport has been investigated in binary solid solutions of triphenylamine and bisphenol‐A‐polycarbonate. Charge was injected from a photoemitting electrode of amorphous selenium. Under space‐charge‐limited conditions, hole transport can be described by a drift mobility that is linearly dependent upon the electric field. For fields of 105V/cm, values of the mobility were between 10−7and 10−5cm2/V s, depending upon the temperature and concentration. The variation with concentration suggests that hole transport occurs by phonon‐assisted hopping between triphenylamine molecules with a charge localization radius of approximately 1.8 A˚.

ISSN:0021-8979    

DOI:10.1063/1.324379

出版商:AIP    

年代:1978

数据来源: AIP

摘要:

The electrical transport properties of splat‐cooled amorphous semiconductors In20Te80, Ga20Te80, and Ge15Te85were investigated by measuring the thermoelectric powerSand dc resistivity &rgr; between 140 and 300 °K. For as‐quenched samples, bothSand log&rgr; show linear relationships with 1/T, indicating ap‐type intrinsiclike conduction ≳90&percent; due to holes. To account for this intrinsiclike conduction, we propose a high degree of structural integrity in the splat‐cooled amorphous samples, i.e., a structure having the homogeneity of the liquid and consisting of continuous Te chains with In, Ga, and Ge attached to broken bonds. However, annealed samples show extrinsiclike conduction from 0 to −130 °C, and bothSand log&rgr; show decrease linearly with respect to the decrease of temperatureT. The effect of heat treatment interpreted as a structural disordering, appears due to atomic segregation at local areas.

ISSN:0021-8979    

DOI:10.1063/1.324380

出版商:AIP    

年代:1978

数据来源: AIP