Volume 9, Issue 11, 01 December 1966
Index of content:
9(1966); http://dx.doi.org/10.1063/1.1754623View Description Hide Description
Experimental results are presented concerning a new form of electric‐field‐induced absorption of infrared light passing through the junction waveguide of a diffused GaAs diode. Changes in absorption constant of nearly 40 cm−1 have been observed at a wavelength of 0.94 μ upon the application of 20 V reverse bias. An explanation involving two physical mechanisms is proposed. The first is a Franz‐Keldysh—like effect associated with shallow impurity levels. The second seems to be associated with a deeper impurity level.
9(1966); http://dx.doi.org/10.1063/1.1754624View Description Hide Description
Measurements of the field near the surface of a Nb‐25% Zr superconducting wire magnetized by a static transverse field have revealed spatially‐periodic variations in local field strength indicative of persistent current loops (``macrovortices'') about six wire diameters in size.
9(1966); http://dx.doi.org/10.1063/1.1754625View Description Hide Description
It has been proposed by Ranganathan that spirals should appear in a field‐ion image when a dislocation intersects the surface. These conditions were simulated with a computer for a fcc lattice using Moore's ``shell model.'' Ranganathan's hypothesis is shown to be exact for the case of a pure screw dislocation intersecting the center of a plane.
9(1966); http://dx.doi.org/10.1063/1.1754626View Description Hide Description
We have observed an interaction between helicon waves and drift currents in a layered lead telluride structure. In the low ω c τ regime of our experiments bulk wave effects are much greater than the surface waveinteraction proposed by Baraff and Buchsbaum. Experiments performed on structures which have layers of equal dielectric constants and those with unequal dielectric constants both yield the same result; namely, the attenuation is reduced when the drift and wave propagate in the same direction and is increased when the two are in opposite directions. The observed interaction is strong and although spatial growth of the helicon waves has not yet been achieved with presently available drift velocities (V drift < V phase), wave attenuation has been reduced by as much as 15 dB.
9(1966); http://dx.doi.org/10.1063/1.1754627View Description Hide Description
Using light scattering and the photoelastic effect, we have investigated the frequency spectrum of giant acoustic shear wave packets generated in semiconducting CdS by high electric fields. The frequencies were in the range 100 to 1500 MHz, at least an order of magnitude lower than the predicted frequency for maximum net gain. The strains were high enough to cause permanent crystal damage.
ELASTIC WAVE AND INFRARED LIGHT INTERACTIONS WITH A MOVING HIGH‐FIELD DOMAIN IN A PIEZOELECTRIC SEMICONDUCTOR9(1966); http://dx.doi.org/10.1063/1.1754628View Description Hide Description
A double‐Doppler‐effect experiment for elastic waves or infrared light, using the moving high‐field domain in a piezoelectricsemiconductor as the moving boundary, is proposed. A possible experimental configuration for the elastic wave case is described and the parameters relevant to the experiment are evaluated for three potential piezoelectricsemiconductors. The most important parameter is the change of acoustic impedance across the boundaries of the high‐field domain. The possibility of employing the proposed experiments as the means for probing the elastic and optical properties of the high‐field domain is also discussed.
9(1966); http://dx.doi.org/10.1063/1.1754629View Description Hide Description
Thick, stable tungstenfilms with fcc structure have been obtained by ion beamsputtering in vacuum onto substrates of glass, rock salt, and mica at a temperature of ∼250–400°C. The lattice constant is 4.15 Å. The fcc phase transforms slowly to bcc at annealing temperatures of ∼700°C.
9(1966); http://dx.doi.org/10.1063/1.1754630View Description Hide Description
A theoretically calculated, automatically plotted, and photoreduced hologram has been successfully used to ``reconstruct'' the image of a nonexistent, three‐dimensional, equilateral tetrahedron. The theory, as presented therein, provides a synthetic hologram which consists only of completely opaque and transparent portions; allows reconstruction of the entire image with any fraction of the hologram as in conventional experimental types; can be made to reconstruct objects for either on‐ or off‐axis viewing; provides both a real and virtual image; and produces a positive image with both positive and negative prints.
9(1966); http://dx.doi.org/10.1063/1.1754631View Description Hide Description
The spectral properties of Nd‐doped YVO4, grown from the melt, have been determined. In absorption the Stark split levels are reduced in comparison to other Nd‐doped materials. The Nd ion appears to be in a cubic crystal field even though it substitutes for Y whose point symmetry is less than . The reduced Stark splitting, caused by an admixture of 4f and 5dwave functions, leads to efficient, low‐threshold laser action. Transfer of energy from the lattice to Nd ions is also observed.
RELATIVE INTENSITIES OF THE 5s 2 P 3/2 → 4p 2 D 5/2 AND THE 5s 4 P 5/2 → 4p 4 D 7/2 TRANSITIONS IN THE Ar II LASER9(1966); http://dx.doi.org/10.1063/1.1754632View Description Hide Description
9(1966); http://dx.doi.org/10.1063/1.1754633View Description Hide Description
Solutions of the Boltzmann equation for GaAs have been used to calculate the variation of drift velocity, vd , with field, E. To represent the situation in moderately doped samples with low mobility an additional scattering process has been incorporated into the calculations. The results are in reasonable agreement with deductions about the vd vs E characteristic made from many types of experiments, but in disagreement with the measured vd vs E of Gunn and Elliott.