摘要:

Ga1−xAlxAs light‐emitting diode structures have been grown on GaP substrates by the liquid‐phase‐epitaxial method. In spite of the large differences in lattice constants and thermal‐expansion coefficients, room‐temperature efficiencies up to 5.5% in air have been observed for a peak emission of 8500 Å. Previously, in order to achieve high external efficiencies it was necessary to grow thick Ga1−xAlxAs layers on GaAs substrates and then remove the substrate. However, using undoped GaP substrates, which are transparent to the infrared and red portions of the spectrum, thin structures of Ga1−xAlxAs with large external efficiencies can now be made.

ISSN:0003-6951    

DOI:10.1063/1.1653981

出版商:AIP    

年代:1972

数据来源: AIP

摘要:

Using a cw tunable PbS0.6Se0.4semiconductor diode laser operating near 5.3 &mgr;m we have fully resolved the gain (loss) line shape of several vibration‐rotation lines of a CO gas laser amplifier.

ISSN:0003-6951    

DOI:10.1063/1.1653982

出版商:AIP    

年代:1972

数据来源: AIP

摘要:

We show experimentally and theoretically that adjustment of a spectrometer for observation of fast‐beam spectral lines under conditions of minimum linewidth requires consideration of the effects of diffraction at the spectrometer's entrance slit. We obtain an approximate expression for the optimum entrance slit width to be used in order to avoid the pronounced broadening of the spectral lines that occurs for very narrow entrance slits.

ISSN:0003-6951    

DOI:10.1063/1.1653983

出版商:AIP    

年代:1972

数据来源: AIP

摘要:

A novel approach using a mixed‐mode transducer for measuring shear‐wave attenuation nearTcin rhenium has been used to show that the shape of the attenuation curve depends on the ultrasonic wave amplitude.

ISSN:0003-6951    

DOI:10.1063/1.1653984

出版商:AIP    

年代:1972

数据来源: AIP

摘要:

Non‐phase‐matched generation of 29.9 cm−1is obtained by difference mixing of pulsed CO2laser radiation in room‐temperature GaAs, with a detection signal‐to‐noise ratio of 103. Calculations show that comparable results could be obtained from 10 to 200 cm−1.

ISSN:0003-6951    

DOI:10.1063/1.1653985

出版商:AIP    

年代:1972

数据来源: AIP

摘要:

A novel planar cold‐cathode structure has been developed based on a GaAs&sngbnd;(AlGa)As heterojunction and a negative electron affinity GaAs surface. As an important feature of the device, the lateral confinement of the current flow to the desired area of the emitting surface is obtained by the selective diffusion of zinc. Under pulsed conditions, emission efficiencies as high as 4% and emission current densities as high as 7 A/cm2have been achieved. The release of impurities from the anode as a result of electron‐stimulated desorption has been found to be a major factor affecting the cathode life under dc operation. The influence of this factor can be greatly minimized by different techniques such as using low anode voltages and magnetic field deflection.

ISSN:0003-6951    

DOI:10.1063/1.1653986

出版商:AIP    

年代:1972

数据来源: AIP

摘要:

The Mo¨ssbauer resonances of nitrogen‐matrix‐isolated57Fe and119Sn atoms have isomer shifts, which are within the experimental errors, identical with the isomer shifts of the same atoms isolated in rare‐gas matrices. Despite an observed quadrupole splitting of the57Fe and119Sn resonances, the relatively small photoelectric cross section of nitrogen makes the nitrogen matrix useful for matrix‐isolation Mo¨ssbauer studies of nuclei which require relatively thick Mo¨ssbauer absorbers.

ISSN:0003-6951    

DOI:10.1063/1.1653987

出版商:AIP    

年代:1972

数据来源: AIP

摘要:

We report here some experimental results on surface‐wave convolution in a structure of Si on LiNbO3or of CdS on PZT. The semiconductor plate is dc biased. Convolved signals at both the sum and difference frequencies have been observed from the terminals attached to the semiconductor. A simple expression is obtained on the convolved signal amplitude vs the difference in wave vectors of the two input signals. The experiment is in general agreement with the theory. A series of pictures on the convolved signal as a function of the applied dc field is presented.

ISSN:0003-6951    

DOI:10.1063/1.1653988

出版商:AIP    

年代:1972

数据来源: AIP

摘要:

The effect of photoconductivity in GaAs single crystals was investigated by using both nanosecond and picosecond light pulses for excitation. Both steady‐state and transient responses of photoconductivity have been observed.

ISSN:0003-6951    

DOI:10.1063/1.1653989

出版商:AIP    

年代:1972

数据来源: AIP

摘要:

We report laser emission from a pulsed transverse electric discharge in fast‐flowing adiabatically cooled gas mixtures. The discharge is in the downstream parallel section of a supersonic nozzle. Both electrical excitation of CO2and CO and chemical excitation of CO in the reaction of CS2+ O2yield laser emission. The cooling in the nozzle is demonstrated by the lowJvalues of the observed transitions. The gain for CO transitions was more than an order of magnitude greater at the low temperatures than at room temperature. Fast cooling during the supersonic expansion permits lasing in highly supersaturated gas mixtures. This extends laser operation to temperatures beyond the capability of cryogenic methods and permits higher laser energies and efficiencies.

ISSN:0003-6951    

DOI:10.1063/1.1653990

出版商:AIP    

年代:1972

数据来源: AIP