摘要:

The photovoltage of silver bromide single crystals has been measured at room temperature as a function of light intensity and wavelength. A two‐part photoresponse was observed: a fast part with a risetime in the millisecond range, followed by a slower part with a response time of seconds. The fast response was nonlinear, the voltage varying approximately as the ⅔ power of the incident light intensity. A model based on a Dember‐type effect was formulated to explain the results. Electrons are assumed to diffuse from the surface into the bulk, owing to their own concentration gradient, while holes are trapped near the surface to form interstitial silver ions which then move under the influence of the field of the electrons. The resulting differential equation was then solved with the aid of a computer. The slow response was ascribed to the effect of photodecomposition products on the initial photovoltage.

ISSN:0021-8979    

DOI:10.1063/1.1657104

出版商:AIP    

年代:1969

数据来源: AIP

摘要:

The interaction energy of two dislocation loops in anisotropic materials is expressed by the Fourier transform of line integrals along the dislocation loops. The result can also be used for the expression of the self‐energy of one dislocation loop. The Fourier integrals are performed for the cases when the elastic constants differ by a small amount from the isotropic elastic constants.

ISSN:0021-8979    

DOI:10.1063/1.1657105

出版商:AIP    

年代:1969

数据来源: AIP

摘要:

The deposition of microdroplets from a nebulized aerosol is enhanced by the application of an electric field. Electronic deposition facilitates the electron microscopic sampling of the aerosol by capturing those microdroplets that are electrically charged or whose dimensions are too small and therefore elude the more conventional methods of collection. The subsequent deposition of the microdroplets in the system described is a function of the strength of the electric field and the size of the individual microdroplets, and therefore negates the use of forced‐air impaction of the microdroplets onto the collecting surface. Electronic deposition as applied to the collection of nebulized suspensions of particulate protein renders the resulting microdroplets (0.25 to 2.0 &mgr; diameter size range) and their contents accessible to sampling under conditions suitable for high‐resolution electron microscopy.

ISSN:0021-8979    

DOI:10.1063/1.1657106

出版商:AIP    

年代:1969

数据来源: AIP

摘要:

The elastic constants of single crystals of the cubic Laves phases ZrCo2and HfCo2were determined by the pulse‐echo technique over the temperature range 4.2°–300°K. Debye temperatures for the two materials were computed from extrapolations of the elastic constants to 0°K. The ratio of these Debye temperatures is such as to indicate that the primary difference between the two materials is a difference in vibrational amplitudes resulting from the mass difference between zirconium and hafnium. Further substantiation of a close similarity of interatomic force interactions in the two materials is obtained by comparison of appropriate combinations of lattice parameters and force constants.

ISSN:0021-8979    

DOI:10.1063/1.1657107

出版商:AIP    

年代:1969

数据来源: AIP

摘要:

The dislocation effects on electrical resistivity and Hall coefficient at the liquid‐nitrogen temperature were examined inn‐type germanium specimens whose dislocation density, distribution, and nature were determined by means of optical and electron microscopy. In particular, the high dislocation density regions were considered, where the space‐charge cylinders and the low‐mobility rings around the dislocations overlap. Three stages were revealed, the first connected with the bulk conductivity, the second with the conductivity in the low‐mobility regions, the third with the prevalence of the minority hole conductivity. The interpretation of the experimental data led to the following determinations: the specific volumes of the space‐charge cylinders and the low‐mobility rings around the edge dislocations; the ratios between low mobility and bulk mobility of the electrons; the degree of the contamination specific of the deformations; the saturation hole concentrations and mobilities. Further, the availability of differentiated specimens with prevalence of either screw or edge dislocations made it possible to resolve the effects of the two types of dislocations.

ISSN:0021-8979    

DOI:10.1063/1.1657108

出版商:AIP    

年代:1969

数据来源: AIP

摘要:

Barrier‐height measurements performed on ultrahigh‐vacuum‐cleaved and on chemically etched ZnSe crystals have shown that for most metals the barrier height increases linearly with its electronegativity. The highly reactive metals Mg, Ca, and Ba were found to be an exception, showing a decrease in barrier height with increasing electronegativity. Aluminum, when diffused into ZnSe from a film deposited onto a vacuum‐cleaved surface, was found to produce a low‐resistivity surface layer, followed by a highly compensated region in the crystal. This effect is suggested to arise from copious generation of Zn vacancies at the Al‐doped crystal surface, and their influx, ahead of the Al, into the crystal.

ISSN:0021-8979    

DOI:10.1063/1.1657109

出版商:AIP    

年代:1969

数据来源: AIP

摘要:

This paper gives a comprehensive description of the breakaway of a dislocation from a row of equally spaced pinning points, under the combined action of stress and temperature, within the model of Teutonico, Granato, and Lu¨cke (TGL). The method is to obtain an algebraic solution, for a general pinning force, using, in turn, the continuous‐pinning approximation of TGL and the ``independent‐joint approximation''; the conditions of validity of these approximations are investigated in detail. For &bgr;«1, the pinning is effectively continuous; here, &bgr;=LcU0/Cr2, whereLcis the distance between pins,U0is the maximum binding energy between a dislocation and a pin,Cis the tension of the dislocation, and the pinning force has its maximum at a displacement of orderr, the ``range.'' For &bgr;»1, the independent‐joint approximation holds (except near the mechanical breakaway stress). Then major breakaway (breakaway from the whole row) is activated at a single pin down to the stress &sgr;s= (4CU0/b2Lc3)1/2, wherebis the Burgers vector. As the stress drops further, a saddle configuration still exists for breaking the first pin, but the dislocation must surmount higher saddle points to break subsequent pins. Major breakaway is activated over an increasing number of pins as the stress decreases, and for &sgr;«&sgr;sthe pinning becomes ``quasicontinuous.'' A paradox encountered by TGL is thus resolved.

ISSN:0021-8979    

DOI:10.1063/1.1657110

出版商:AIP    

年代:1969

数据来源: AIP

摘要:

Room‐temperature transverse magnetoresistance measurements onn‐type PbS films are reported. The results are different for magnetic fields perpendicular and parallel to the film faces. This anisotropy is sensitive to ambient and is understandable in terms of a model consisting of ann‐type bulk region andp‐type surface space‐charge layer.

ISSN:0021-8979    

DOI:10.1063/1.1657012

出版商:AIP    

年代:1969

数据来源: AIP

摘要:

The impulse response in distributed‐parameter systems results in a spectrum of delta functions in the time domain forLCstructures. It is shown that forRCstructures the impulse response results in a spectrum of Poisson‐derived functions in the reciprocal time domain. This isomorphism is exploited for the analysis ofRCdevices to establish a calculus of Poisson‐derived functions and a transform technique which is essentially the Laplace transform. Applications of this technique to thin‐film devices and minority‐carrier devices are examined and lead to the determination of the transient response for one‐ports and two‐ports that are subject to a wide range of terminations. Illustrative examples of excitations include the impulse, the step, and the ramp, as well as signals generated by the distributed parameter devices themselves. Significant advantages accrue from a spectral description ofRCdevices in the reciprocal time domain: (1) conceptual, by establishing a physical interpretation based on diffusion phenomena; (2) analytical, by developing a systematic approach to transients paralleling the network function approach in the frequency domain; (3) computational, by expressing the response by a rapidly converging spectrum of functions.

ISSN:0021-8979    

DOI:10.1063/1.1657013

出版商:AIP    

年代:1969

数据来源: AIP

摘要:

Transient analysis for uniformRCstructures is considered in this paper. A method is presented for determining the parameters of such structures. The measurements are obtained using impulse excitations in open‐circuit and short‐circuit configurations. The theoretical results obtained predict fairly the experimental results.

ISSN:0021-8979    

DOI:10.1063/1.1657014

出版商:AIP    

年代:1969

数据来源: AIP