摘要:

Basic formulas have been obtained for the contribution to the potential in any point of a cylindrical or toroidal volume with rectangular sectional shapes and rotation‐symmetrical boundary conditions. This is done by solving Laplace’s equation in cylindrical coordinates using the method of separation of variables for the cases in which simple but characteristic rotation‐symmetrical potential overlays on the boundaries exist. Knowing these solutions and limiting the widths of the areas where the potential overlays are defined, differential contributions to the potential in any point of the observed volumes in analytical form are derived. With these solutions also numerical formulas for the contribution in a point of the volume can be formulated so that the relaxation method can be avoided.

ISSN:0021-8979    

DOI:10.1063/1.323139

出版商:AIP    

年代:1976

数据来源: AIP

摘要:

An empirical relation is presented which allows simple computation of volume‐averaged winding fields from central fields for coils of small rectangular cross sections. This relation suggests that, in certain applications, ac‐loss minimization can be accomplished by use of low winding densities, provided that hysteresis losses are independent of winding density. ac‐loss measurements on coils wound of twisted multifilamentary composite superconductors show no significant dependence of ac losses on winding density, thus permitting the use of winding density as an independent design parameter in loss minimization.

ISSN:0021-8979    

DOI:10.1063/1.323140

出版商:AIP    

年代:1976

数据来源: AIP

摘要:

The lattice defects in nitrogen‐doped GaP light‐emitting diodes (LED’s) are investigated by taking an electroluminescence (EL) pattern and an x‐ray topograph of a small LED chip. The one‐to‐one correspondence between the dark lines in the EL pattern and the screw dislocations is obtained.

ISSN:0021-8979    

DOI:10.1063/1.323141

出版商:AIP    

年代:1976

数据来源: AIP

摘要:

High‐speed silicon avalanche photodiodes for the near‐infrared region are reported. Diodes are provided with a built‐in field by a graded impurity distribution which accelerates photocarriers in a light‐absorption region. The response for a mode‐locked Nd : YAG laser pulse is as narrow as 200 psec. Typical quantum efficiency is 0.55 at 0.80 &mgr;m and 0.49 at 0.83 &mgr;m. The gain‐bandwidth product is 460 GHz at a multiplication factor of 400. The built‐in field is effective in realizing high‐speed avalanche photodiodes with a low breakdown voltage.

ISSN:0021-8979    

DOI:10.1063/1.323142

出版商:AIP    

年代:1976

数据来源: AIP

摘要:

The effective distribution coefficient of phosphorus during growth of Ga1−xAlxAs1−yPyby liquid‐phase epitaxy is of particular importance to the growth of heteroepitaxial structures for injection lasers and light‐emitting diodes. In these structures small additions of P (y<0.02) can be used for stress compensation and for lowering of laser threshold. In this work, Auger spectroscopy was combined with ion milling for quantitative chemical analysis and depth profiling. Belowy=0.02 (withx=0.36) and cooling rate of 0.1 °C/min for growth,kpwas found to be 290 at a growth temperature of 790 °C and remained constant down to at leasty=0.002. This high value ofkpcaused depletion of P from the growth solution and gave rise to P concentration profiles in the epitaxial layer which decreased with distance away from the substrate.

ISSN:0021-8979    

DOI:10.1063/1.323143

出版商:AIP    

年代:1976

数据来源: AIP

摘要:

Field emission from single crystals of LiIn, which behave as either narrow‐gap semiconductors or semimetals, have been studied using a field emission microscope. A linear Fowler‐Nordheim relationship was found. The specimen surfaces were believed to be contaminated.

ISSN:0021-8979    

DOI:10.1063/1.323144

出版商:AIP    

年代:1976

数据来源: AIP

摘要:

The simplified particle model theory of diffuse reflectance spectroscopy is used to relate the reflectance and transmittance of a powdered layer to the fundamental optical parameters. The resulting equations are compared with those obtained by the use of the Kubelka‐Munk theory.

ISSN:0021-8979    

DOI:10.1063/1.323145

出版商:AIP    

年代:1976

数据来源: AIP

摘要:

The transient and steady‐state domain‐wall velocities are measured by a refined collapse method in a bubble garnet film. The usual average velocity as a function of pulse width shows very large velocity for short pulse width and relaxation to the steady state. The instantaneous velocity defined simply from the increments of wall displacement distance and pulse width shows that the velocity is nearly steady over about 10 ns. The steady‐state velocity below the drive field of 500 Oe includes both a velocity component independent of drive field and a component increasing linearly with field. The former mode is not operative above 900 Oe. These are discussed from the theoretical predictions, together with the wall velocity in hard bubbles.

ISSN:0021-8979    

DOI:10.1063/1.323146

出版商:AIP    

年代:1976

数据来源: AIP

摘要:

Direct two‐component color superposition for field‐ion microscopy is extended to three‐component color superposition. Details of the method are given and some applications are mentioned.

ISSN:0021-8979    

DOI:10.1063/1.323147

出版商:AIP    

年代:1976

数据来源: AIP