摘要:

The growth of silicon dioxide in a microwave discharge was investigated. The oxide growth can be characterized by a rate‐limiting diffusion process modified by sputtering effects produced by the discharge. Analysis of the growth behavior leads to the conclusion that a limiting oxide thickness is obtained at infinite time. The growth process provides a technique for rapidly oxidizing silicon at temperatures estimated to be 500°C or lower. At these low temperatures, growth rates corresponding to steam‐oxidization rates at 1100°C can be obtained. Films about 2000 Å thick can be grown in five minutes, and about 6000 Å thick in sixty minutes. High‐quality oxides are produced by this process with properties which are for the most part indistinguishable from those of thermally grown oxides. MOS capacitance—voltage measurements indicate that these oxides are essentially free of mobile ions.

ISSN:0021-8979    

DOI:10.1063/1.1709122

出版商:AIP    

年代:1967

数据来源: AIP

摘要:

Several possible mechanisms for generation of high electrical potentials in supersonic nozzles are examined. It is suggested that charge transfer between condensate particles and the probe, due to a contact potential, occurs during particle—probe collisions. A high electrical‐probe potential develops as the kinetic energy of the charged particles in the gas flow is converted to electrical energy. This conversion is possible because the particles are massive and have a low mobility. It is suggested that particle mobility and probe voltage—current measurements can yield size and energy information about the condensate particles.

ISSN:0021-8979    

DOI:10.1063/1.1709123

出版商:AIP    

年代:1967

数据来源: AIP

摘要:

The magnetoresistance, Hall effect, and electrical conductivity of bismuth have been investigated to 90 kbar. In phase I, the application of pressure decreases the number of carriers; pressure increases the hole mobility so that both electrons and holes are approximately equally mobile just before the I–II transformation occurs. These observations may be explained by an upward shift of the light carrier bands relative to the heavy carrier bands. The magnetoresistance and Hall coefficients indicate simple metallic behavior for phases II, III, and IV.

ISSN:0021-8979    

DOI:10.1063/1.1709124

出版商:AIP    

年代:1967

数据来源: AIP

摘要:

CaF2:Ho3+has been reported as a visible laser at 5512 Å. Operation is at a relatively high threshold power due, principally, to weak and narrow absorption lines.Preliminary experiments, using Eu2+as a sensitizer, have indicated that an order of magnitude increase in Ho3+, 5512‐Å emission intensity may readily be achieved through transfer of energy from Eu2+to Ho3+ions. Dopant concentrations, for each constituent, were nominally <1 mole%.

ISSN:0021-8979    

DOI:10.1063/1.1709125

出版商:AIP    

年代:1967

数据来源: AIP

摘要:

Evidence for defect centers having an ionization energy atEv+0.10 eV in melt‐grown GaAs is given based on: (1) Hall‐effect measurements on Cu‐diffused crystals. (2) Residual64Cu left in GaAs after extraction by indium. (3) Decrease in electron concentration of donor‐doped crystals after annealing. The failure to observe the defect level in photoluminescence is discussed. The results suggest that Ga vacancies are present in clusters in melt‐grown GaAs crystals.

ISSN:0021-8979    

DOI:10.1063/1.1709126

出版商:AIP    

年代:1967

数据来源: AIP

摘要:

An experimental and theoretical study is made of current nonsaturation phenomena in cesium vapor, thermionic diodes. It is shown that ion flow from the plasma to the emitter electrode produces a significant nonsaturation effect. It is also shown that this ion current produces a high‐sheath field at the emitter which accentuates the nonsaturation through the Schottky and anomalous Schottky effects. These effects are incorporated into an analysis of diode behavior. It is shown that the expected diode behavior due to ion‐current and Schottky effects is consistent with available experimental data.

ISSN:0021-8979    

DOI:10.1063/1.1709127

出版商:AIP    

年代:1967

数据来源: AIP

摘要:

A low‐energy electron diffraction (LEED) system has been used to study the energy spectra of Auger electrons from clean and alkali‐covered Ge and Si surfaces. Auger bands characteristic of the substrates were observed for the clean surfaces and the deposition of submonolayer coverages of K and Cs introduced new bands characteristic of the respective alkali. It is shown that a surface impurity in a quantity as small as 0.1 monolayer can be detected and identified by this measurement.

ISSN:0021-8979    

DOI:10.1063/1.1709128

出版商:AIP    

年代:1967

数据来源: AIP

摘要:

The superconducting properties of Tc‐V alloys with compositions ranging from 0 to 100 at.% V have been investigated in fields up to 15 kOe by measurements of the bulk magnetization determined ballistically. A phase diagram of the Tc‐V system has been determined by several metallurgical techniques. The sequence of crystal structures at 1500°C with increasing vanadium content is hcp→bcc→CsCl→bcc. The technetiumrich bcc phase when quickly cooled to room temperature exhibits superlattice x‐ray diffraction lines of the CsCl structure. The superconducting transition temperature of the technetium‐rich hcp alloys increases with vanadium concentration from 7.73°K to a maximum for the system of 11.3°K at the limit of vanadium solubility (∼6.5 at.% V). This transition temperature remains constant for the two‐phase alloys. The transition temperature decreases progressively with increasing vanadium content in the CsCl structure, and at compositions in the 50 to 80 at.% V interval no evidence of superconductivity is observed for temperatures as low as 1.4°K. Alloys containing the hcp phase show reversible behavior in the tails of their magnetization curves, while those with the CsCl structure exhibit a high degree of hysteresis in the tails. Estimates of the upper‐critical field at 0°K,HC2(0), using the experimental data and theoretical calculations yield values ofHC2(0) to approximately 45 kOe for the samples with high‐transition temperatures. Results of heat treatment at 1100°C on the superconducting parameters of alloys near the 30 at.% V composition are presented.

ISSN:0021-8979    

DOI:10.1063/1.1709129

出版商:AIP    

年代:1967

数据来源: AIP

摘要:

The allowed directions for phase‐matched second‐harmonic generation in acentric biaxial crystals are obtained by considering the intersections of the index surfaces at the fundamental and harmonic frequencies; the topology of these intersections is determined by the principal refractive indices. There are thirteen distinguishable cases for optically well‐behaved biaxial crystals and the phase‐matching directions for them are shown as loci on the stereographic projection. Phase‐matching that is insensitive to small changes in the direction of propagation is possible when some principal refractive indices are equal; the mismatch of the wave vectors is given for deviations from the phase‐matching direction in such cases. The disposition of the principal axes of the optical indicatrix and the symmetry of the point groupsC2v,D2,Cs,C2, andC1are examined to find those situations which have a nonzero element in the second‐order polarizability tensor that will give second‐harmonic generation.Phase‐matched second‐harmonic generation experiments in the biaxial crystals dipotassium tartrate, lithium sulfate and ammonium oxalate demonstrate some of the possible phase‐matching situations.

ISSN:0021-8979    

DOI:10.1063/1.1709130

出版商:AIP    

年代:1967

数据来源: AIP

摘要:

The extension of Sommerfield's problem to a moving semi‐infinite lossless medium is considered in this paper. The analysis is limited to the determination of the space wave in the far zone. This is the geometrical optics solution of the problem and is carried out simply by utilizing the results of the plane‐wave reflection—refraction problem obtained in a previous paper. The study includes both the vertical and the horizontal dipoles. As expected, the motion of the medium does not significantly affect the radiation pattern unless the velocity is comparable with that of light.

ISSN:0021-8979    

DOI:10.1063/1.1709131

出版商:AIP    

年代:1967

数据来源: AIP