摘要:

Visible light‐emitting diodes have been fabricated from Cd1−xMgxTe (x≈ 0.43). An external quantum efficiency of 2×10−4has been obtained at room temperature. Emission spectra of the diodes consist of two broad bands peaking at 640 and 700 m&mgr;, relative intensities of which depend on the concentration of Al doped as donors. The photoluminescence measurements indicate that the 640‐m&mgr; band is produced by a combination of doping P as an acceptor and heating in Cd vapor. The 700‐m&mgr; band is enhanced by Al and is attributable to lattice defects induced by Al doping.

ISSN:0003-6951    

DOI:10.1063/1.1654242

出版商:AIP    

年代:1972

数据来源: AIP

摘要:

In our work on the amplification of Bleustein‐Gulyaev waves in photoconducting CdS crystals, we have found that the gain as a function of electric field is quite symmetric about the synchronous value. We have therefore been able to achieve amplification with a segmented structure consisting of an interdigital electrode. The unequal spacing between fingers produces amplification in the region where the field is positive, which is in excess of the attenuation in the region where the field is negative. The spacings between adjacent electrodes are 500 and 250 &mgr;m, giving a periodicity of 850 &mgr;m; the length of the active region is 6 mm. The experimental electronic gains obtained were 19 dB at 43 MHz and 32 dB at 86 MHz with an applied voltage of 130 V; 4 dB net gain was obtained at 86 MHz. It has been observed that the electronic gain is sensitive to the photoexciting light wavelength. We give an interpretation of this phenomenon based on the relative penetration depth of the mechanical wave, of the photoexcited carriers, and of drifting electric field.

ISSN:0003-6951    

DOI:10.1063/1.1654243

出版商:AIP    

年代:1972

数据来源: AIP

摘要:

We report on an experimental study of the nonlinear interaction of Bleustein‐Gulyaev surface waves in photoconducting CdS. The two oppositely travelling surface waves at frequencyf=43 MHz are first amplified and then interact under a semitransparent diffused electrode. The acoustic convolution product is observed at 86 MHz. The level of the detected signal is 36 dB below the two input ones with an interacting length of only 2 mm. There is clear evidence that this nonlinear interaction results from electron phonon scattering; we give the expression for the second‐order potential.

ISSN:0003-6951    

DOI:10.1063/1.1654244

出版商:AIP    

年代:1972

数据来源: AIP

摘要:

Rare‐earth oxysulfide films with an intrinsic cathodoluminescent efficiency equivalent to that of the same material in powder form have been produced. These films withstood the maximum power density of the electron beam apparatus, 7 W/mm2, without damage or intensity saturation. An apparatus‐limited luminance of 4×104fL from a terbium‐activated lanthanum oxysulfide film using 12‐kV cathode‐ray excitation was measured. A multilayer film of lanthanum oxysulfide activated with Eu, Tb, and Tm was produced whose emission color is voltage dependent.

ISSN:0003-6951    

DOI:10.1063/1.1654245

出版商:AIP    

年代:1972

数据来源: AIP

摘要:

It is found that when a short‐duration plane‐compressive stress pulse is propagated in various solid metals, the initially compressive pulse develops a tensile tail indicative of dispersion. This dispersion occurs without the stress pulse impinging upon external boundaries or upon any classically recognized internal boundaries. This phenomenon also occurs in water in which it is demonstrated experimentally that the dispersion mechanism is the scattering of the wave by the small amount of air normally present in water. It is believed that the pulse dispersion in the metals is likewise caused by scattering of the wave by the very small but extremely numerous defect‐related voids that exist in all metals, even if they are carefully prepared metallic single crystals.

ISSN:0003-6951    

DOI:10.1063/1.1654246

出版商:AIP    

年代:1972

数据来源: AIP

摘要:

A germanium prism coupler has been used to couple a CO2laser beam into thin AgBr films deposited on NaCl substrates. Thermographic phosphor screens and an infrared scanner were used to detect guided‐wave propagation in the films. Measurement of the TE0and TM0coupling angles yielded the film index (2.14) and thicknesses. The latter were in excellent agreement with independent thickness measurements.

ISSN:0003-6951    

DOI:10.1063/1.1654247

出版商:AIP    

年代:1972

数据来源: AIP

摘要:

Laser emission from vibrationally excited CO (CO†) has been observed when mixtures of CSe2, O2, and He are partially dissociated by a pulsed electric discharge. Observations on the spontaneous emission confirm that the CO†is formed in the reaction O + CSe → CO†+Se, which is 118 kcal/mole exothermic and produces CO selectively in high vibrational levels. A comparison is made with the analogous system O + CS → CO†+S.

ISSN:0003-6951    

DOI:10.1063/1.1654248

出版商:AIP    

年代:1972

数据来源: AIP

摘要:

Observations of backward stimulated Brillouin scattering (SBS) in glass optical fibers are reported. Threshold for SBS has been achieved with less than 1 W of input power at 5355 Å. Relaxation behavior in the SBS signal has also been observed and is attributed to finite‐cell‐length oscillation. Experimental results are compared with theory, and the implied limitation to optical fiber transmission is discussed.

ISSN:0003-6951    

DOI:10.1063/1.1654249

出版商:AIP    

年代:1972

数据来源: AIP

摘要:

We report here the results of a preliminary study of coherent microwave radiation emitted by a small array of interacting Josephson tunnel junctions, including the first direct observation of the superradiant state in pairs of junctions.

ISSN:0003-6951    

DOI:10.1063/1.1654250

出版商:AIP    

年代:1972

数据来源: AIP

摘要:

The on‐state of the chalcogenide glass threshold switch is analyzed on experimental results which call for thin free‐carrier space‐charge regions at the electrodes. Carriers are assumed to tunnel through the corresponding barriers which are, in turn, maintained by the joint action of the electron and hole flow. The calculated voltage‐current relationship is in excellent agreement with observations.

ISSN:0003-6951    

DOI:10.1063/1.1654251

出版商:AIP    

年代:1972

数据来源: AIP