摘要:

The critical current density vs applied transverse magnetic field was measured, for a superconducting niobium single crystal of controlled oxygen content, at successively higher levels of concentration; the oxygen content was increased in increments ranging from 2 to 50 ppm, under conditions of constant substructure, from an initial level of approximately 5 ppm to a final level of 360 ppm. The over‐all critical current density increased considerably on the addition of oxygen, and assuming &ggr; to be independent of oxygen concentration, the upper critical field increases in accordance with the predictions of the GLAG theory for type II superconductivity. The critical current density above the upper critical field, which has been ascribed to nucleation effects at defects or surfaces, was also very sensitive to the oxygen content.

ISSN:0021-8979    

DOI:10.1063/1.1713866

出版商:AIP    

年代:1965

数据来源: AIP

摘要:

Hall and field‐effect surface mobility has been measured in polycrystalline films of CdS of thickness 1000–4000 Å. At low surface potential, the mobility increases with surface potential. The Hall mobility was observed to increase exponentially with temperature from −80° to 120°C. These effects can be explained using a polycrystalline film model. The effects of diffuse surface scattering were not observed at low surface potential due to the small mean free path of electrons. However, when the channel thickness was comparable to the electron mean free path a decrease in mobility was observed.

ISSN:0021-8979    

DOI:10.1063/1.1713867

出版商:AIP    

年代:1965

数据来源: AIP

摘要:

The shape dependence of the profiles of alloy junctions formed on {111} and {1¯1¯1¯} surfaces of InSb has been studied as a function of alloying conditions. Polarity‐dependent effects are found which may be attributed to different dissolution rates for {111} and {1¯1¯1¯} surfaces. Direct evidence of this difference is presented. By proper choice of alloying conditions it is possible to obtain planar junctions on both types of surface. The rectification ratios of such junctions prepared on either surface range from 107to 2×108, at 250 mV. The polar differences in the current‐voltage characteristics of these junctions are small and tentatively attributed to polarity‐dependent surface effects.

ISSN:0021-8979    

DOI:10.1063/1.1713868

出版商:AIP    

年代:1965

数据来源: AIP

摘要:

The Nernst coefficientQwas measured forn‐type InSb in the temperature range 260° to 340°K and magnetic field range 4 to 12 kG. For indium antimonide the difference between the adiabatic and isothermal Nernst coefficients is negligible. The method of measurement of the true Nernst voltage is similar to that for the Hall effect. In addition to variation with temperature,Qalso varies appreciably with magnetic field. The Hall coefficient, electrical conductivity, and Righi‐Leduc temperature difference were also measured. The experimental values ofQshow poor correlation with those based on the Lorentz‐Sommerfeld theory.

ISSN:0021-8979    

DOI:10.1063/1.1713869

出版商:AIP    

年代:1965

数据来源: AIP

摘要:

A current‐controlled negative resistance phenomenon, similar to that exhibited by a gas discharge tube, has been observed in suitably prepared thin oxide films of Nb, Ta, and Ti, sandwiched between thin‐film metal electrodes, at frequencies up to 1 Mc/sec. The voltage required to sustain the negative resistance in both directions of current is independent of the electrode materials, apparent area and thickness (up to 500 Å) of the oxide film, and is about 0.4, 1.3, and 3.5 V for Ti, Nb, and Ta oxide films, respectively. The corresponding electric fields are approximately 0.8×106, 3×106, 9×106V/cm. These values increase slightly with decrease of temperature. Experimental evidence supports the interpretation of the phenomenon in terms of avalanche multiplication of carriers in a thin region of the oxide film attended by space‐charge‐limited flow conditions.

ISSN:0021-8979    

DOI:10.1063/1.1713870

出版商:AIP    

年代:1965

数据来源: AIP

摘要:

The decrease of the emission efficiency of hot electrons from a reverse‐biased silicon junction has been measured as a function of time after etching. The decrease is largely due to a change in the surface potential of the silicon emitter. A density of surface states of 8×1012/cm2has been determined from the effective attenuation distance of the hot electrons in the growing surface oxide layer, and from the characteristic energy of the emitted electrons. Changes in emission efficiency due to interface and oxide layer scattering have been determined from the emission efficiency for the more energetic electrons. A linear growth rate of the surface oxide induced by continuous charging of the surface states has been found.

ISSN:0021-8979    

DOI:10.1063/1.1713871

出版商:AIP    

年代:1965

数据来源: AIP

摘要:

It is shown from an analysis of the propagation characteristics of a plane polarized wave in an artificial dielectric that Faraday rotation would be produced. Numerical results forn‐type InSb indicate that the rotation should be experimentally observable. Some practical applications of the phenomenon are suggested.

ISSN:0021-8979    

DOI:10.1063/1.1713873

出版商:AIP    

年代:1965

数据来源: AIP

摘要:

Electronic currents in insulators are strongly controlled by trap sites and therefore trapping can account for long‐term charge and discharge currents. Some general calculations are carried out for the discharge of disorderly insulators; in most cases the discharge current decreases inversely with time. Measurements are demonstrated for SiO2and SiO.

ISSN:0021-8979    

DOI:10.1063/1.1713874

出版商:AIP    

年代:1965

数据来源: AIP

摘要:

Experimental techniques have been developed for measuring the Seebeck coefficientSand electrical resistivity &rgr; of liquid semiconductors at high temperatures. Data have been obtained forS(T) and &rgr;(T) in a temperature range of 200° to 800°C and a composition range of 31 to 68 at.% of thallium. The liquids arentype for compositions with more than 66% thallium, andptype for lower thallium concentrations. At several compositions where thermal conductivity data are available, evaluation of the thermoelectric figure of merit &ggr;(=ZT) shows ranges of relatively large values of &ggr;(0.1 to 0.85).

ISSN:0021-8979    

DOI:10.1063/1.1713876

出版商:AIP    

年代:1965

数据来源: AIP

摘要:

In an abrupt Ge‐GaAsp‐nheterojunction, a plot of conduction band edge vs position shows a discontinuity at the material interface. As a result, a ``notch'' occurs in the band‐edge profile which strongly affects the opto‐electric characteristics of such a junction. The conversion efficiency is much less than that of a homojunction of similar doping levels. At room temperature the photocurrent is limited by the rate at which electrons can be thermally excited from the notch into the GaAs. At 78°K this contribution to current is negligible. For reverse bias, the photocurrent results from electron tunneling from the notch into the GaAs. In forward bias, the space charge resulting from the presence of the optically excited electrons in the notch changes the potential profile in such a way so as to reduce the forward current, and to cut it off entirely for sufficiently high light intensity. Because of the low conversion efficiency, it is concluded that such a heterojunction collector in an optical transistor is not practical.

ISSN:0021-8979    

DOI:10.1063/1.1713877

出版商:AIP    

年代:1965

数据来源: AIP