摘要:

The electron transmission coefficient for an asymmetric double barrier model of a thin‐film triode is discussed. Two resonant terms appear in the transmission expression, one of which depends on the relative properties of the barriers and the other on the thickness of the base or control film. The results of a detailed calculation for a simplified model are given.

ISSN:0021-8979    

DOI:10.1063/1.1729551

出版商:AIP    

年代:1963

数据来源: AIP

摘要:

When the anodic films of Ta2O5or of SiO2, each having the thickness 100∼2500 Å, are heated at high temperatures in contact with MnO2layers, they exhibit rectifying actions ofp‐i‐njunction type as well as large electromotive forces in the direction of easy flow resulting from the ion flow through the films. The short‐circuit ion current increases greatly with increasing temperature, while the open‐circuit voltage increases rapidly at first with increasing temperature, reaches a maximum, and then decreases gradually at higher temperatures.The results obtained are analyzed in the light of ap‐i‐njunction structure in the film. In the steady states the observed current through the external circuit is equal to the sum of the ion current, the generation, and recombination current, and the leakage current of the junction. Theoretical expressions having an explicit form are given forIionandIf, by making the assumptions that (a) the built‐in voltage in the junction is equal to the free‐energy change in the reaction of film formation and (b)Ifis of the Sah‐Noyce‐Shockley type. Agreement between the theory and experiments is excellent. We believe that the present method of investigation could also be applied in the elucidation of the growth mechanism as well as of the electric properties of films formed on other metals or semiconductors.

ISSN:0021-8979    

DOI:10.1063/1.1729552

出版商:AIP    

年代:1963

数据来源: AIP

摘要:

A triple correlator of fluctuating photocurrents is shown to be able to analyze asymmetrical spectrum profiles of light beams, such as laser beams, without the use of an additional light source. The resolving time of photodetectors, multipliers, and electronic delay lines involved must be shorter than the coherence time of the light beam to be analyzed. The method cannot determine the mean frequency of an incident beam and cannot distinguish between a spectrum profile and its mirror image around the mean frequency.

ISSN:0021-8979    

DOI:10.1063/1.1729553

出版商:AIP    

年代:1963

数据来源: AIP

摘要:

Pb&sngbnd;Al2O3&sngbnd;Pb structures have been fabricated by vacuum evaporation. For oxide thickness of approximately 300 Å, a forming process was noted. This forming process resulted in large electron transfer currents which were described as the sum of a temperature‐independent current plus a current with a voltage and temperature dependence appropriate to Schottky field emission into a solid. The forming process is assumed to be due to the establishment of a positive ion space charge which increases the field at the cathode.

ISSN:0021-8979    

DOI:10.1063/1.1729554

出版商:AIP    

年代:1963

数据来源: AIP

摘要:

One of the major problems in oscillistor work is connected with the stability and reproducibility of the surface conditions of the oscillistor specimen. An empirical surface treatment has been found which enables one to prepare reasonably reproducible and stable oscillistors. By utilizing this surface treatment, it has been possible to measure the conditions existing at the onset of current oscillations. The quantitative dependence of the minimal applied magnetic field required for oscillistor action has been measured as a function of applied voltage and specimen size. Some qualitative information regarding the dependence of the minimal applied magnetic field on bulk and surface properties has been inferred from the experimental data. These data reveal that there is an optimum size for oscillistor specimens that will minimize the electrical input power required for oscillations, and by using such samples, oscillistors have been fabricated that will function continuously at room temperature. An experiment designed to interact with the magnetic field produced by the helical perturbation proposed by Glicksman has disclosed a new effect that may provide a way of constructing an oscillistor amplifier.These experiments have revealed that the conditions necessary for oscillations in the current are quantitatively different from the conditions necessary for oscillation of the components of electric field that are transverse to the applied electric field. Since no quantitative theory of the mechanism of current oscillation has appeared in the literature, no direct comparison between theory and experiment is possible. However, the applied electric and magnetic fields required for current oscillations are of the same order of magnitude as those predicted by the existing helical instability theories.

ISSN:0021-8979    

DOI:10.1063/1.1729555

出版商:AIP    

年代:1963

数据来源: AIP

摘要:

Contact of a negatively charged microprobe to the (0001) face of a silver‐backed Madagascar &agr;quartz crystal at temperatures between 300–573°C produced four distinct types of visible decorations. The most prominent of these were conducting metallic platelets on the basal plane about 0.4 &mgr; thick, with surface areas ranging up to the dimensions of the anode. The growth of these platelets appeared to take place only at the periphery, and to be thermally activated with dependence upon field &egr; of the form exp[−(H0−&bgr;&egr;½)/RT], where &bgr;=0.32 kcal/[mole(V/cm)½] andH0=38 kcal/mole. Metallic platelets which formed deep within the crystal bulk, having relatively large surface area usually caused the crystal to fracture. The migration of silver through the crystal bulk was observed to take place only in the [0001] direction. Geometric patterns showing the sixfold symmetry of the basal plane were observed to form, at or near the crystal surface, within a fraction of a second upon the application of a negative probe to the (0001) face. Probe currents, both axial and equatorial, were found to be thermally activated with energies between 38 and 39 kcal/mole for conduction not involving the transport of silver ions. Platelet formation in synthetic quartz crystals differed markedly from that for natural quartz. Instead of a conducting metallic platelet, an irregular dendritic growth appeared.

ISSN:0021-8979    

DOI:10.1063/1.1729556

出版商:AIP    

年代:1963

数据来源: AIP

摘要:

Several divalent and trivalent rare‐earth ions incorporated in various host crystals have been found to exhibit stimulated emission in the near infrared. A report is presented describing some of the basic characteristics of these materials: absorption and fluorescence spectra, energy level diagrams, optical maser wavelengths and operating temperatures, and thresholds for stimulated emission. Recent observations on the CaWO4:Nd3+optical maser in continuous operation are also described.

ISSN:0021-8979    

DOI:10.1063/1.1729557

出版商:AIP    

年代:1963

数据来源: AIP

摘要:

The energy ratios of reflected and refracted waves to the incident wave at ten liquid‐solid boundaries are calculated as a function of the angle of incidence. The influence of the wave velocities in the media and their density on the shape of the curves is discussed.

ISSN:0021-8979    

DOI:10.1063/1.1729558

出版商:AIP    

年代:1963

数据来源: AIP

摘要:

It is shown that the contribution of thermal diffuse scattering to integrated Bragg intensities from perfect crystals can be much greater than previously expected. Measurements on the (555) reflection of silicon are presented showing a thermal scattering contribution of about 70% of the true Bragg intensity. The special aspect of the effect in perfect crystals is discussed and methods of reducing it or correcting for it are included.

ISSN:0021-8979    

DOI:10.1063/1.1729559

出版商:AIP    

年代:1963

数据来源: AIP

摘要:

The high contrast resolving power of several photographic thermal neutron image detection methods has been experimentally determined. For the most part, the comparisons between the different imaging techniques were made after optimizing each technique for resolution capabilities. The resolution was studied by determining the minimum hole separation in an almost totally absorbing object which could be resolved by a number of observers on neutron radiographs made by each method. From the standpoint of resolution, the best methods employed thin gadolinium metal screens, compressed Li‐6F powder, and a thin B‐10 layer covered with a vapor deposited ZnS (Ag) phosphor in techniques in which the photographic film and screen were exposed together to the low gamma content, 1.05 Å monochromatic neutron beam. A transfer of an image carrying radioactive gold screen to film also yielded resolution values in the order of 0.001 in. Evidence is presented to explain many of the observed resolution comparisons on the basis of the average penetrating power of the photographically effective radiation emitted from the converter screen. A technique for measuring this property on a comparative basis is described.

ISSN:0021-8979    

DOI:10.1063/1.1729560

出版商:AIP    

年代:1963

数据来源: AIP