摘要:

The electrodeposition technique previously developed by the present authors forinsitugrowth ofp‐type CdTe thin films, has been further improved using As as an acceptor dopant. Photovoltaic‐quality films were grown on conducting glass and Mo substrates and characterized by scanning electron microscopy, electron probe microanalyses, and Auger electron spectroscopy. These films were subsequently utilized in the construction of inverted photovoltaic cell structures comprising then‐CdS/p‐CdTe heterojunction. Efficiencies approaching the 5% level (AM1 insolation) have been obtained thus far on small‐area (∼0.20 cm2) devices.

ISSN:0021-8979    

DOI:10.1063/1.335735

出版商:AIP    

年代:1985

数据来源: AIP

摘要:

Rapidly rotating, large‐diameter rings have potential for use as low‐cost electrical‐energy storage devices. The efficiency of passive electromagnetic and electrodynamic methods to confine the rotating rings is investigated. Confinement methods examined include repulsive image force, repulsive null flux, attractive image force, and radially stable attractive. For each method the decay time is given in terms of the ring material properties and design parameters. The repulsive techniques are shown to have decay times of less than a day when optimized within a set of practical design constraints. The two attractive levitation methods result in the largest decay times, but are inherently unstable. When null‐flux stabilizers are used with attractive levitation, the decay time is shown to depend on magnetic field inhomogeneity. Finally, an inherently stable and very efficient attractive levitation method is proposed. The new method is based on an analogy with alternating‐gradient synchrotrons and should have application in high‐speed ground transportation.

ISSN:0021-8979    

DOI:10.1063/1.335736

出版商:AIP    

年代:1985

数据来源: AIP

摘要:

Dislocation effect upon the efficiency of single‐crystal thin‐film AlGaAs‐GaAs heteroface solar cells on Si substrates is analyzed. Solar‐cell properties are calculated based on a simple model; in the model, dislocations act as recombination centers to reduce the minority‐carrier diffusion length in each layer and increase the space‐charge layer recombination current. Numerical analysis is also carried out to optimize thin‐film AlGaAs‐GaAs heteroface solar‐cell structures. The fabrication of thin‐film AlGaAs‐GaAs heteroface solar cells with a practical efficiency larger than 18% on Si substrates appears possible if the dislocation density in the thin‐film GaAs layer is less than 106cm−2.

ISSN:0021-8979    

DOI:10.1063/1.335737

出版商:AIP    

年代:1985

数据来源: AIP

摘要:

High‐voltage silicon photoconductive switches require pulse bias in order to prevent thermal runaway. The behavior of these devices during pulse bias cannot be modeled by standard steady‐state current equations (Ohm’s law). This paper shows that the observed nonlinear behavior is due to plasma injection, describes an analysis of this transient current flow during pulse bias, and shows it to be in good agreement with our experimental results. This paper further verifies the charge injection by showing that the leakage current can be reduced by thin trap layers directly underneath the metal contacts.

ISSN:0021-8979    

DOI:10.1063/1.335738

出版商:AIP    

年代:1985

数据来源: AIP

摘要:

Electromagnetic surface waves can propagate along boundaries between electrically different media like air and earth or sea water and rock. They have unusual properties that make them valuable tools in geophysical prospecting and diagnostics. They are not suited to deep sounding. Much of the current theory for their geophysical application has been limited to ranges of the parameters and variables that permit the use of Norton’s graphs which were developed for radio communication over the earth. A recently derived set of accurate, very general, and simple formulas for the surface‐wave fields of antennas near a boundary surface has provided an expanded horizon for understanding and using surface waves as distinct from plane waves that travel down into the earth. The new formulas are given and used to assist in the interpretation of available measurements and then applied to the determination of the average conductivity and permittivity of the part of the lithosphere very close to the sea bottom where the lateral waves travel.

ISSN:0021-8979    

DOI:10.1063/1.335739

出版商:AIP    

年代:1985

数据来源: AIP

摘要:

A field analysis is developed for the helical slow‐wave structure of a traveling‐wave tube in the anisotropic sheath helix model considering the effects of the azimuthal harmonics generated due to periodical positioning of the support bars around the helix. A practical relevance is added to the problem by way of considering the effect of an overall metal enclosure; the losses of the structure are, however, ignored. The analytical result justifies the usual heuristic approach of treating the support bars as a continuous dielectric of a suitably interpreted permittivity.

ISSN:0021-8979    

DOI:10.1063/1.336294

出版商:AIP    

年代:1985

数据来源: AIP

摘要:

The results of magnetic measurements performed onxFe2O3(1−x)[yB2O3 PbO] glasses havingy=0.5, 1, 2, and 3 andx≤25 mol % Fe2O3are reported. For identical Fe2O3content the Curie constants are greater as the PbO content of the glass matrix is higher. This is due to the increase of the fraction of Fe3+ions as evidenced by Mo¨ssbauer effect measurements. As B2O3content increases, a more random distribution of the ferric ions in the glass matrix takes place. Under the action of fast neutrons some iron ions situated in clusters are displaced and occupy sites more randomly distributed in the B2O3‐PbO matrix. In addition, a fraction of ferrous ions is converted to ferric.

ISSN:0021-8979    

DOI:10.1063/1.335740

出版商:AIP    

年代:1985

数据来源: AIP

摘要:

We have determined that silicon films have nearly ideal properties for use as a diffusion mask and encapsulation coating for InP and GaAs. The Si films, composed of a single element, are easily and reproducibly deposited by electron beam evaporation at low temperatures. Sharp features can be defined by standard photolithography and freon‐plasma etching. The thermal coefficient of expansion of silicon nearly matches that of InP and GaAs so that problems due to film stress are avoided. Additionally, the interaction of Si with InP and GaAs crystals, under severe thermal treatments often used in device fabrication, was found to be negligible. Finally, we found that the Si film acts as a good diffusion mask for Zn which is a commonp‐type impurity for formingp‐njunctions in III‐V compounds.

ISSN:0021-8979    

DOI:10.1063/1.335741

出版商:AIP    

年代:1985

数据来源: AIP

摘要:

The rarefaction of a shock‐heated solid surface into vacuum and the luminous radiation emitted by the surface were studied using a one‐dimensional hydrodynamic code. The temporal evolution of the spectral and brightness temperatures as observed by a remote detector was determined. Moreover, the time‐integrated spectral temperature was computed to simulate the actual experimental measurements. For shock speeds greater than 106cm/s and for measurement times exceeding a few picoseconds, the code predicted a significiantly lower ‘‘observed’’ temperature, in good agreement with experiments.

ISSN:0021-8979    

DOI:10.1063/1.335742

出版商:AIP    

年代:1985

数据来源: AIP

摘要:

This communication disputes the claim made by Ternan [J. Appl. Phys.57, 1743 (1985)] that the Ampere and Lorentz force laws are equivalent. Two examples are quoted in which the two laws make different predictions. Particle beams in vacuum obey Lorentz’s law but in metallic circuits Ampere’s law prevails.

ISSN:0021-8979    

DOI:10.1063/1.335743

出版商:AIP    

年代:1985

数据来源: AIP