摘要:

Grain boundaries inn‐type germanium and silicon carry a negative surface charge and constitute a potential barrier for electrons. The height of this barrier can be increased by applying an electrical pulse across the boundary or decreased by injecting holes. The relaxation time with which the perturbed barrier returns to its equilibrium value is for sufficiently low temperatures very large compared to the time necessary to change the barrier height. A theory of the transient response of a grain boundary to a pulse is given for the low temperature region. It is shown that the application of a pulse of given height results in a barrier height &fgr;swhich is practically independent of the barrier height &fgr;aprior to the pulse. The transient current, however, depends markedly on &fgr;a. A novel photosensor based on this phenomenon is described, and preliminary experimental results are reported.

ISSN:0021-8979    

DOI:10.1063/1.1776972

出版商:AIP    

年代:1959

数据来源: AIP

摘要:

The ferroelectric properties of the calcium borate mineral colemanite are investigated in the ferroelectric and paraelectric temperature regions. It is shown that Devonshire's phenomenological theory may be applied successfully to account for the experimental measurements of spontaneous polarization and electrical susceptibility over a wide temperature range. The thermodynamic transition is confirmed to be of second order occurring for unbiased crystals at −7°C. It is shown, in general, that the temperature &tgr;0at which such a transition takes place depends upon the effective electric fieldEas &tgr;0=kE⅔wherekis a constant evaluated from Devonshire's expansion. The effect of space charge fields are evaluated and a comparison is presented between the ferroelectric properties of colemanite and those of KDP.

ISSN:0021-8979    

DOI:10.1063/1.1776973

出版商:AIP    

年代:1959

数据来源: AIP

摘要:

An investigation was made of the combustion of stoichiometric mixtures of hydrogen and oxygen with a varying percent of helium in the constant volume driver section for a hypersonic shock tunnel. The pressure was measured as a function of time for a number of initial pressures, mixture ratios, and multiple sparks for ignition. The maximum pressures observed were close to that expected for smooth burning. When detonation was encountered, the ratio of the peak pressure to the initial pressure was about 50.

ISSN:0021-8979    

DOI:10.1063/1.1776974

出版商:AIP    

年代:1959

数据来源: AIP

摘要:

The detailed behavior of a solid cylindrical electron beam focused by a uniform magnetic field (Brillouin flow) has been studied experimentally. These studies include the influence of the optics of the electron gun on the beam‐focusing characteristics, the effects of transverse ``thermal'' velocities, the change in the internal beam dynamics with increasing values of magnetic focusing field, etc. A simple model of the beam is used to explain certain of the observed characteristics. It is found that an optically good electron gun will produce a focused beam which closely resembles the theoretical Brillouin‐flow model. A brief analysis of the electron motion in a magnetically focused beam is given in the Appendix.

ISSN:0021-8979    

DOI:10.1063/1.1776975

出版商:AIP    

年代:1959

数据来源: AIP

摘要:

The electrical properties of a fluctuating bistable microplasma are specified by three parameters which, in general, are functions of voltage. For an ideal low impedance connection, these parameters are independent of time and thus yield simple forms for the pulse rate, average current, differential conductance, and noise spectral density. With a high impedance circuit the phenomenon is more complex, and only an approximate analysis is offered. Measurements on alloyed junctions with breakdown voltages between 7.9 and 10.5 v show that single breakdown regions sometimes occur at low currents. Multistable conduction as well as the simpler bistable conduction is observed. The multistable conduction is characterized by fluctuations among higher current levels which occur at a rate 102–105times faster than the ``on‐off'' fluctuations. Excellent agreement between measured and calculated current spectral density at low impedance is found. This justifies the assumptions of random events independent of previous ``on'' or ``off'' time and suggests that noise spectrum measurements at low impedance be used as a tool for accurately determining the microplasma parameters. With a high impedance connection, the process is not Markoffian; thus the noise is not simply related to the noise at low impedance. The event which initiates breakdown is found to be field dependent suggesting that field emitted carriers are involved. It is shown that the results do not fully agree with those predicted by Rose's model of a microplasma.

ISSN:0021-8979    

DOI:10.1063/1.1776976

出版商:AIP    

年代:1959

数据来源: AIP

摘要:

Measurements of the electrical conductivity &sgr;, the thermal conductivityK, and the Seebeck coefficient (thermoelectric power) &agr;, of InAs1−xPxhave been made at high temperatures withxvarying from 0 to 0.4. Between 450° and 800°C, the average thermoelectric figure of merit (z= &agr;2&sgr;/K) increases moderately withxfor small values ofx, reaching a maximum nearx= 0.1, and subsequently decreasing. Between 450 and 800°C, the averagezforx= 0.1 is equal to 0.63 × 10−3(°K)−1, a 15% improvement over InAs. For the same figure of merit, the Seebeck coefficient and electric resistivity is higher in the ternary than in the binary InAs; this is advantageous for the design of thermoelectric devices. Previous values for the thermoelectric figure of merit of InAs are revised.

ISSN:0021-8979    

DOI:10.1063/1.1776977

出版商:AIP    

年代:1959

数据来源: AIP

摘要:

New techniques are proposed for the measurement of lifetime in semiconductors by utilizing the absorption of microwave power by charge carriers. The densities of holes and electrons are varied by irradiation with light or the conduction mechanism. Agreement is found when the microwave absorption methods are compared with the more established photoconductivity decay techniques. One of the new methods offers an advantage in that electrode attachments are no longer required.

ISSN:0021-8979    

DOI:10.1063/1.1776978

出版商:AIP    

年代:1959

数据来源: AIP

摘要:

The reasons for the initial choice of ruby as a maser material are outlined and some measurements of the parameters in the spin Hamiltonian and of spin relaxation times are reported. The relative merits of single‐ and double‐pump modes of operation of a four‐level maser are discussed and measurements of the oscillator power for the two cases are included.

ISSN:0021-8979    

DOI:10.1063/1.1776979

出版商:AIP    

年代:1959

数据来源: AIP

摘要:

The orientations and sizes of all the grains in a polycrystalline disk specimen of high‐purity 3.25% silicon iron are measured to determine a calculated magnetic torque curve and the texture of the specimen. The torque results agree with the experimentally determined values. The curves approximate a (110) [001] single crystal torque curve, which is reduced about 75%, and thus indicate a possible texture consisting of about 25% (110) [001] and 75% random. The true texture obtained from the orientation data is found to have more than ten components, none of which is (110) [001]. Illustrations showing how a (110) [001] type torque curve may be synthesized from non‐(110) [001] type components in the texture are given.

ISSN:0021-8979    

DOI:10.1063/1.1776980

出版商:AIP    

年代:1959

数据来源: AIP

摘要:

At fields in the range 30–35 v cm−1, polarization reversal in liquid‐electroded triglycine sulfate crystals is accomplished by the formation and sideways expansion of a relatively few domains. While small, the domains are elliptical or lenticular in shape, but as they grow, they tend to become irregular before amalgamating with each other. In some cases, at least, the elliptical domains have approximately equilibrium shapes as determined by the wall energy. Some general results are given concerning the sites at which the domains form and the way in which domains contract when the field is reversed.

ISSN:0021-8979    

DOI:10.1063/1.1776981

出版商:AIP    

年代:1959

数据来源: AIP