摘要:

To understand ``fatigue'' or ``burn‐in'' in the target of a PbO Vidicon, experiments have been made with sandwich cells of evaporated PbO. It has been demonstrated by using chopped radiation that as the PbO layer fatigues, there is an increase in short term dark conductivity. Further, it has been shown that the phenomenon is associated with loss of oxygen from the surface of the crystals during irradiation with photons. A surface chemistry model similar to one proposed by Morrison and Melnick in connection with ZnO is used to explain the observed results.

ISSN:0021-8979    

DOI:10.1063/1.1728546

出版商:AIP    

年代:1962

数据来源: AIP

摘要:

A simple method, utilizing a noninductive connection, is described for the direct measurement of the resistive component of the potential drop across a semi‐enclosed arc. By this method the resistance, power dissipation, and efficiency are determined for an arc due to a capacitor discharge having a peak current of about 2.5×105A. The minimum resistivity is found to be 1.5×10−3&OHgr; cm, a value lower than values reported previously. A current curve is analyzed to determine resistance of the entire circuit. Inductance interrelation are considered further.

ISSN:0021-8979    

DOI:10.1063/1.1728547

出版商:AIP    

年代:1962

数据来源: AIP

摘要:

The conditions for the observation of space‐charge‐limited (SCL) transient current pulses in insulators are examined. A parameter &agr;=2tr/&tgr; (tr=space‐charge‐free transit time and &tgr;=response time of the circuit) is defined, whose value determines the extent to which the pulses are distorted from their ideal shape. For &agr;>100, the pulses are undistorted. For 20<&agr;<100, the pulse shape becomes distorted from the ideal case and for &agr;<20, pulses begin to be indistinguishable. It is shown that carrier transport inanyinsulator may be investigated by transient SCL current measurements provided that trapping is not too severe and that ohmic contact formation (either transient or steady‐state) is possible.

ISSN:0021-8979    

DOI:10.1063/1.1728548

出版商:AIP    

年代:1962

数据来源: AIP

摘要:

A novel method for sputtering insulators in the plasma of a low‐pressure discharge is described. The method utilizes rf fields whereby the positive charge accumulation at the target surface, resulting from positive ion bombardment, is periodically neutralized during each cycle. The method has many useful applications for cleaning, etching, and sputtering of insulators, as well as for removing deposits from observation windows.

ISSN:0021-8979    

DOI:10.1063/1.1728549

出版商:AIP    

年代:1962

数据来源: AIP

摘要:

Expressions are derived that enable calculation of the effects of space charge on the current density of electrons tunneling from a metal into the conduction band of an insulating film. The effect of electron traps in the insulating material is considered. It is shown that if the insulating film contains a high trap density, space charge can severely limit the tunnel current density that can be achieved, even for very thin films.

ISSN:0021-8979    

DOI:10.1063/1.1728550

出版商:AIP    

年代:1962

数据来源: AIP

摘要:

The method of calculating rf excitation by the Cˇerenkov effect using Lorentz transformations, first used by Nag and Sayied in the case of a single electron and an infinite dielectric medium, was extended to a modulated electron beam in the presence of a finite dielectric boundary. A relation between the Cˇerenkov effect and Roentgen surface current was pointed out.

ISSN:0021-8979    

DOI:10.1063/1.1728551

出版商:AIP    

年代:1962

数据来源: AIP

摘要:

A simple empirical analysis allowing the prediction of the energy gaps of the III–V semiconductors and the rare‐earth nitride, phosphide, and arsenide semiconductors is given. The analysis is based on a correlation of the semiconductor energy gaps with the ionic and covalent atomic radii of the constituent elements and is not sensitive to changes in crystal structure in going from one compound to the other. Excellent agreement is obtained between the predicted and existing experimental values. Certain of the predictions are at variance with previously predicted values and the need for experimental work to decide between the alternative treatments is indicated.

ISSN:0021-8979    

DOI:10.1063/1.1728552

出版商:AIP    

年代:1962

数据来源: AIP

摘要:

A method of obtaining an exact circuit equivalence of a class of coupled transmission systems from Maxwell's equations is described. The solution for the propagating characteristics of the coupled transmission system can be readily obtained from the circuit analog. The process of reducing field equations to circuit equations is carried out for a particular coupled structure, a coupled helix system. The circuit theory yields frequencies of the coupled modes as functions of the propagation constant, rather than the propagation constant in terms of frequency. The circuit theory has the great advantage that it is as valid for strongly coupled systems as it is for weakly coupled systems. The usefulness of the approach is demonstrated by applying the theory to several slightly different propagating systems.Expressions for the energy and the power flow derived from the circuit theory are compared to the true power flow and the energy in the transmission system. It is shown that the energy of the system in the equivalent transmission line corresponds to the true energy, if the circuit is assumed to propagate slow waves. The power flow relation obtained from the circuit analog differs from the true power flow by the factor of (vp/vg) which is attributed to the dispersive nature of the circuit. Important relationships between impedances of the transmission system defined in various ways are obtained from the power flow relation.

ISSN:0021-8979    

DOI:10.1063/1.1728553

出版商:AIP    

年代:1962

数据来源: AIP

摘要:

The effect of zirconium on internal friction in columbium was investigated over the frequency range of 0.5 to 10 cps. An entirely new peak was observed which was attributed to the diffusion of oxygen in the vicinity of zirconium atoms. The normal columbium oxygen peak was not observed until approximately 0.14 wt% oxygen was added to the specimens. The normal columbium‐nitrogen peak was readily observed, but a zirconium‐nitrogen peak was not observed until oxygen concentration was reduced below 0.1 wt%. These observations are explained on the basis of a strong attraction between zirconium and oxygen atoms. As a preliminary to this investigation, the diffusivity of zirconium in columbium at 1930°C was determined. A value forD0and the activation energy were calculated so that the diffusivity at any temperature could be obtained from the expressionD=0.57 exp 87 000/RT.

ISSN:0021-8979    

DOI:10.1063/1.1728554

出版商:AIP    

年代:1962

数据来源: AIP

摘要:

Non‐ohmic behavior of the current voltage characteristic was noted on high‐resistivity silicon carbide crystals with fused tungsten contacts. In order to explain the shapes and magnitudes of these characteristics the theory of two‐carrier space‐charge‐limited currents was employed. Calculations with this treatment gave a common electron and hole lifetime of ∼5×10−5sec, a recombination cross section of ∼4×1019cm2, and a current enhancement factor of ∼103.

ISSN:0021-8979    

DOI:10.1063/1.1728555

出版商:AIP    

年代:1962

数据来源: AIP