摘要:

Pyroelectric voltage transients obtained from modified Pb(Ti0.07Zr0.93)O3ceramics in response to step ir signals were studied between 20 and 100 °C, in which range theFR(LT)‐FR(HT)transition occurs. The temperature dependences of peak voltage and total released charge exhibit a pronounced peak at about 85 °C with a small temperature hysteresis indicating that this transition is not purely of second order. The pyroelectric coefficient between room temperature and the transition temperature increases by about a factor 10. The dynamical behavior and the dielectric properties are discussed and their potential for the development of ir devices operating at or near this phase transition is outlined.

ISSN:0003-6951    

DOI:10.1063/1.88481

出版商:AIP    

年代:1975

数据来源: AIP

摘要:

As‐grown silicon crystals are investigated in the scanning electron microscope using Schottky barrier diodes in the electron‐beam‐induced current mode. Dislocations,A‐ andB‐type swirl defects, as well as dopant striations are detected. In high‐resistivity crystals (∼1000 &OHgr; cm) variations in dopant concentration of 1012cm−3are readily revealed. Hydrogen doping is found to eliminate preferential recombination at microdefects. It is established that bulk stresses due to carbon striations have no detectable electrical effect.

ISSN:0003-6951    

DOI:10.1063/1.88482

出版商:AIP    

年代:1975

数据来源: AIP

摘要:

The effect of cold rolling on the structure of a metallic glass Pd0.775Cu0.06Si0.165and a crystalline Pd has been investigated using positron annihilation methods. Only slight change in both the positron lifetime and angular distribution upon cold rolling has been noted for the metallic glass. This is in strong contrast to a large change observed for the crystalline Pd. It is therefore concluded that cold rolling of the metallic glass induces no vacancylike defects. It is also suggested that the local atomic rearrangements during plastic deformation may lead to the densification of the metallic glass.

ISSN:0003-6951    

DOI:10.1063/1.88483

出版商:AIP    

年代:1975

数据来源: AIP

摘要:

The yield ratio of diatomic versus atomic secondary ion emission from metals and semiconductors has been studied using two different mass spectrometers. Under ultrahigh vaccum conditions and with argon primary ions, yield ratios in excess of unity were observed for a variety of elements at secondary ion energies below about 10 eV.

ISSN:0003-6951    

DOI:10.1063/1.88484

出版商:AIP    

年代:1975

数据来源: AIP

摘要:

We take macroscopic (x‐ray attenuation) and microscopic (Mo¨ssbauer line broadening) measurements of ions diffusing in a cold liquid. Combined, the results demonstrate that jumps the size of lattice dimensions donottake place, in contrast to crystalline diffusion. Surprisingly from molecular dynamical considerations,Dis Arrhenius‐like over four decades.

ISSN:0003-6951    

DOI:10.1063/1.88485

出版商:AIP    

年代:1975

数据来源: AIP

摘要:

Stimulated emission from theB2&Sgr; state of CO+has been observed as a consequence of the charge transfer reaction between He+2and CO in the afterglow of a Febetron 706 discharge into 3 atm of helium containing 1.0 Torr of carbon monoxide. Peak gains of the order of 0.08 cm−1were found for the (0,2) vibrational component of theB2&Sgr;→X2&Sgr; transition at 2470 A˚ by directly measuring the time‐resolved amplification of suitably filtered light from a xenon flashlamp. Correspondingly smaller gain, persisting for several hundred nanoseconds, was found for the (0,0) and (0,1) vibrational components of theB2&Sgr;→A2&Pgr; transitions at 3954 and 4210 A˚, respectively.

ISSN:0003-6951    

DOI:10.1063/1.88486

出版商:AIP    

年代:1975

数据来源: AIP

摘要:

Cross sections of (100)Si/(012)sapphirewere examined by transmission electron microscopy. The foil plane was (011)Siand contained the [1¯00]Sigrowth direction. The number of faults (i.e., microtwins and isolated stacking faults) per cm measured in the [022]Sidirection, FD, decreases with increasing distancedfrom the silicon/substrate growth interface according to the equations FD= (3.1×107)/d0.63(440⩽d⩽2400 A˚), and FD= (1.3×1011)/d1.7(2400?d?4.3×104A˚). Misfit dislocations were not observed, and no evidence for the presence of an Al‐bearing phase was seen in the proximity of the interface.

ISSN:0003-6951    

DOI:10.1063/1.88487

出版商:AIP    

年代:1975

数据来源: AIP

摘要:

Filament profiles in cw stripe‐geometry homostructure GaAs lasers are measured from below to well above threshold through their optical spectra. It is shown that the filament appears well below threshold and its dimensions are not a strong function of injection level and consequently of the optical field intensity. These results are at variance with previously published theories.

ISSN:0003-6951    

DOI:10.1063/1.88488

出版商:AIP    

年代:1975

数据来源: AIP

摘要:

We report the measurement of impact ionization rates for electrons and holes in the direct band‐gap semiconductor alloy In0.14Ga0.86As. Our results show clearly that the ionization rate for holes is greater than that for electrons. The measurments were made for electric fields between 2.6×105and 3.4×105V cm−1. In this range, the ionization coefficients can be expressed as &agr;=&agr;∞ exp(‐A/E) for electrons and &bgr;=&bgr;∞ exp(‐B/E) for holes with &agr;∞=1.0×109cm−1,A=3.6×106V cm−1, and &bgr;∞=1.3×108cm−1,B=2.7×106V cm−1.

ISSN:0003-6951    

DOI:10.1063/1.88489

出版商:AIP    

年代:1975

数据来源: AIP

摘要:

Optical characteristics of B (group‐III) isoelectronic impurity in AlxGa1−xAs (x=0.37) are investigated by photoluminescence measurements. Two new bands are observed at 2 K in B‐implanted and annealed AlxGa1−xAs. One band is at 167.4 meV below the edge emission line, the other at 23.5 meV. The latter is observed clearly only through time‐resolved spectroscopy, because the donor‐acceptor pair emission almost overlaps the band. These observations suggest that the B impurity makes bound states in AlxGa1−xAs.

ISSN:0003-6951    

DOI:10.1063/1.88490

出版商:AIP    

年代:1975

数据来源: AIP