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1 Apr 1974

Volume 24, Issue 7, pp. 297-343


Plasma‐polymerized films as orientating layers for liquid crystals

J. C. Dubois, M. Gazard, and A. Zann

Appl. Phys. Lett. 24, 297 (1974); http://dx.doi.org/10.1063/1.1655190 (1 page) | Cited 12 times

Online Publication Date: 9 October 2003

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Plasma‐polymerized films from hexamethyldisiloxane are suitable for giving a homeotropic alignment to p‐methoxybenzylidene, p, n‐butylaniline. A 500‐Å‐thick layer of this polymer on substrates gives a very stable liquid crystal orientation.

Effect of dielectric anisotropy on twisted nematics

A. I. Baise and M. M. Labes

Appl. Phys. Lett. 24, 298 (1974); http://dx.doi.org/10.1063/1.1655191 (3 pages) | Cited 6 times

Online Publication Date: 9 October 2003

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The electrical and optical threshold voltages for the twisted nematic field effect have been measured using Schiff base mixtures having Δϵ values from 2 to 16. The electrical threshold was measured by capacitance techniques, and was smaller than the optical threshold by a factor of ∼ 1.5. By using response time data to estimate changes in average elastic constants of the mixtures, the expected variation of the electrical threshold with Δϵ was found.

Ion‐beam production using thermionic ion emission from sodium silicate in a plasma

N. Sato, Y. Hatta, R. Hatakeyama, and H. Sugai

Appl. Phys. Lett. 24, 300 (1974); http://dx.doi.org/10.1063/1.1655192 (3 pages) | Cited 6 times

Online Publication Date: 9 October 2003

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By using thermionic ion emission from a water glass (sodium silicate, Na2O ⋅ 2SiO2) an ion beam is easily produced in a plasma. Possible applications of the ion emission to plasma diagnostics are also described.

Formation of a virtual cathode by a relativistic electron beam flowing through a cavity

M. Friedman

Appl. Phys. Lett. 24, 303 (1974); http://dx.doi.org/10.1063/1.1655193 (3 pages) | Cited 9 times

Online Publication Date: 9 October 2003

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A region of strong electric field (i.e., a virtual cathode) is formed when a relativistic electron beam is forced to flow through a cavity. This region is located at the entrance of the cavity and significantly affects the behavior of the beam.

Generation of bandwidth‐limited pulses from a TEA CO2 laser using p‐type germanium

A. F. Gibson, M. F. Kimmitt, and B. Norris

Appl. Phys. Lett. 24, 306 (1974); http://dx.doi.org/10.1063/1.1655194 (2 pages) | Cited 22 times

Online Publication Date: 9 October 2003

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Passive mode locking of a TEA CO2 laser using p‐type germanium as a saturable absorber is described. Pulses of about 0.5‐ns duration are obtained.

Phase‐matched three‐wave mixing in silica fiber optical waveguides

R. H. Stolen, J. E. Bjorkholm, and A. Ashkin

Appl. Phys. Lett. 24, 308 (1974); http://dx.doi.org/10.1063/1.1655195 (3 pages) | Cited 57 times

Online Publication Date: 9 October 2003

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We have observed phase‐matched nonlinear mixing in a silica fiber optical waveguide using the dispersion of the guide modes to compensate for bulk dispersion. A tunable dye laser signal is mixed with a fixed‐frequency pump wave to generate output in specific waveguide modes at different frequencies. The technique is useful as a probe of waveguide properties and for the study of the nonlinearities of the medium.

Spontaneous and stimulated carrier lifetimes (77°K) in GaAs1−xPx and GaAs1−xPx : N

M. H. Lee, N. Holonyak, J. C. Campbell, W. O. Groves, M. G. Craford, and D. L. Keune

Appl. Phys. Lett. 24, 310 (1974); http://dx.doi.org/10.1063/1.1655196 (4 pages) | Cited 6 times

Online Publication Date: 9 October 2003

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By means of optical phase shift measurements at low and high excitation levels, spontaneous and stimulated carrier lifetimes are determined (77°K) as a function of photon energy on nitrogen‐doped and nitrogen‐free n‐type GaAs1−xPx. Spontaneous lifetime data near laser threshold on N‐free samples show the effect of stimulated emission and intraband adjustment of electrons during sample fluorescence. Above threshold the lifetime drops sharply in the vicinity (energy or wavelength) of the sample peak laser output. Nitrogen‐doped samples show, in addition, the effect of electron transfer from the conduction band to the NN‐pair states, supporting in the process laser operation on the nitrogen states.

``Stopping effect'' on guided light in As☒S films by a laser beam

A. Matsuda, H. Mizuno, T. Takayama, M. Saito, and M. Kikuchi

Appl. Phys. Lett. 24, 314 (1974); http://dx.doi.org/10.1063/1.1655197 (2 pages) | Cited 9 times

Online Publication Date: 9 October 2003

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An optical ``stopping effect'' on guided light in As☒S films has been achieved using a He☒Cd laser beam. Preliminary results of this newly found phenomenon are presented in this paper.

X‐ray emission from a CO2‐laser‐produced plasma

P. E. Dyer, D. J. James, S. A. Ramsden, and M. A. Skipper

Appl. Phys. Lett. 24, 316 (1974); http://dx.doi.org/10.1063/1.1655198 (2 pages) | Cited 10 times

Online Publication Date: 9 October 2003

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A 0.3‐GW, 60‐ns TEA CO2 laser has been used to create plasma from a solid carbon target. Studies of the x‐ray emission from the plasma at 4×1011 W∕cm2 indicate the existence of a high‐energy electron component with an equivalent temperature of ∼ 2 keV.

Observation of strong bulk oxidation effects in amorphous germanium by ultraviolet reflectance spectroscopy

C. R. Helms, W. E. Spicer, and V. Pereskokov

Appl. Phys. Lett. 24, 318 (1974); http://dx.doi.org/10.1063/1.1655199 (3 pages) | Cited 5 times

Online Publication Date: 9 October 2003

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The effect of air exposure on the reflectance of evaporated amorphous and crystalline germanium for photon energies 2.5 ≤ h ν ≤ 11.7 eV has been studied in order to compare their oxidation rates. For h ν≳4 eV, much larger changes in reflectance are observed in the amorphous films than are found in the crystalline films.

Zinc ion implantation into GaAs0.62P0.38

Tadatsugu Itoh and Yasuhisa Oana

Appl. Phys. Lett. 24, 320 (1974); http://dx.doi.org/10.1063/1.1655200 (3 pages) | Cited 4 times

Online Publication Date: 9 October 2003

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The effects of dose, implantation temperatures, and annealing on the electrical properties of Zn‐implanted GaAs0.62P0.38 were measured. Zinc ion implantation was performed with 20‐keV ions at temperatures between room temperature and 450 °C. The abnormal property that the effective surface concentration exceeds the implanted Zn dose was obtained for the samples implanted at room temperature.

Thermally stimulated current measurements and their correlation with efficiency and degradation in GAP LED'S

E. Fabre and R. N. Bhargava

Appl. Phys. Lett. 24, 322 (1974); http://dx.doi.org/10.1063/1.1655201 (3 pages) | Cited 29 times

Online Publication Date: 9 October 2003

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Thermally stimulated current (TSC) measurements have been performed on p‐n junctions in GaP grown by double liquid phase epitaxy. Several deep states have been observed in both the n and p sides of the junction, and a correlation has been established between the presence and concentration of some of these traps and the quantum efficiency of the corresponding light‐emitting diode (LED). It has also been observed that the degradation of the LED by heating under forward bias leads to the appearance or increase of the intensity of some peaks in the TSC spectrum.

Degradation‐induced microwave oscillations in double‐heterostructure injection lasers

E. S. Yang, P. G. McMullin, A. W. Smith, J. Blum, and K. K. Shih

Appl. Phys. Lett. 24, 324 (1974); http://dx.doi.org/10.1063/1.1655202 (4 pages) | Cited 19 times

Online Publication Date: 9 October 2003

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Microwave oscillations in the light output of mesa‐stripe GaAs☒Ga1−xAlxAs double‐heterostructure lasers have been observed after degradation. The same lasers showed no oscillations before degradation. The experimental evidence indicates that the oscillations are caused by repetitive Q switching, with dark‐line regions in the degraded units acting as saturable absorbers.

Luminescence, laser, and carrier‐lifetime behavior of constant‐temperature LPE In1−x Gax P (x=0.52) grown on (100) GaAs

J. C. Campbell, W. R. Hitchens, N. Holonyak, M. H. Lee, M. J. Ludowise, and J. J. Coleman

Appl. Phys. Lett. 24, 327 (1974); http://dx.doi.org/10.1063/1.1655203 (4 pages) | Cited 12 times

Online Publication Date: 9 October 2003

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Photoluminescence and carrier lifetime data are obtained on low‐dislocation‐density (etchpits ≳5×103/cm2) n‐type In1−x Gax P (x=0.52) epitaxial layers grown on (100) surfaces of GaAs by means of a constant‐temperature liquid‐phase‐epitaxial (CT‐LPE) process. These crystals are of exceptional quality and readily lase from 77 to 300 °K. The index dispersion relation (n‐λ dn∕dλ) is determined from the laser mode spacing Δλ in the temperature range 77–300 °K and indicates that at higher thresholds laser operation shifts toward donor tail states. By means of optical phase shift measurements the carrier lifetime (77°K) is examined as a function of wavelength from the spontaneous regime to well above laser threshold. The lifetime data indicate that there is a correlation between a dip in the lifetime due to stimulated emission and the region of the spectrum where the first laser modes appear. These data, and similar data on p‐type crystals, indicate that CT‐LPE In1−x Gax P should be very promising for the development of room‐temperature visible spectrum lasers.

Amorphous semiconductor devices displaying memory in one polarity and threshold switching in the opposite polarity

R. Vogel Nicolaides

Appl. Phys. Lett. 24, 331 (1974); http://dx.doi.org/10.1063/1.1655204 (3 pages) | Cited 1 time

Online Publication Date: 9 October 2003

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A novel switching effect has been found in amorphous semiconductor devices having an aluminum interlayer on one electrode. These devices operate as memory devices in one polarity and as threshold switching devices in the opposite polarity. The setting time is very short if the aluminum side of the device is positive. If no aluminum interlayer is present, a long pulse with special trailing edge is necessary to accomplish memory setting. Threshold switching voltage and memory breakdown voltage of the device with an interlayer have the same value.

Threshold effects and large Tc reductions in neutron‐irradiated A‐15 superconductors

Donald G. Schweitzer and Don M. Parkin

Appl. Phys. Lett. 24, 333 (1974); http://dx.doi.org/10.1063/1.1655205 (3 pages) | Cited 7 times

Online Publication Date: 9 October 2003

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A‐15 superconductors show very large decreases in critical temperature after 60 °C neutron irradiations exceeding about 1018 neutrons∕cm2 (E>1 MeV). These effects are not observed in superconductors such as Nb, NbN, or Nb☒Ti.

Josephson junctions at 45 times the energy‐gap frequency

D. G. McDonald, F. R. Petersen, J. D. Cupp, B. L. Danielson, and E. G. Johnson

Appl. Phys. Lett. 24, 335 (1974); http://dx.doi.org/10.1063/1.1655206 (3 pages) | Cited 5 times

Online Publication Date: 9 October 2003

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Superconductive Nb☒Nb point contacts have been studied with 9.5‐μm radiation from CO2 lasers. Two models are considered to explain the experiments: one is Werthamer's Josephson junction model and the other is a thermally modulated Josephson junction. The evidence favors Werthamer's model but is not conclusive.

Residual surface resistance of superconductors at microwave frequencies

E. P. Kartheuser and Sergio Rodriguez

Appl. Phys. Lett. 24, 338 (1974); http://dx.doi.org/10.1063/1.1655207 (3 pages) | Cited 6 times

Online Publication Date: 9 October 2003

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A microscopic theory of the residual surface resistance is presented and compared with experimental results in superconducting lead and niobium. It is shown that for frequencies above 1 GHz, direct electromagnetic generation of acoustic shear waves can account for the measured residual surface resistance.

Effect of pulse shaping on laser‐induced spallation

Jay A. Fox

Appl. Phys. Lett. 24, 340 (1974); http://dx.doi.org/10.1063/1.1655208 (4 pages) | Cited 6 times

Online Publication Date: 9 October 2003

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Photographic evidence is presented of the back‐face spallation of 1.0‐mm 6061‐T6 aluminum samples irradiated in vacuum by 1.5‐nsec 1.06‐μ laser pulses. Thinner samples (0.5 mm) have also been spalled and complete back‐face separation has been achieved. It is demonstrated that the degree of spallation is a strong function of fluence and that target coupling can be enhanced by means of prepulses.
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Erratum: Optically stimulated x‐ray laser

Isaac Freund

Appl. Phys. Lett. 24, 343 (1974); http://dx.doi.org/10.1063/1.1655209 (1 page)

Online Publication Date: 9 October 2003

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