摘要:

High external quantum efficiencies have been obtained for GaP red‐emitting diodes fabricated by a single liquid‐phase epitaxy, in which Zn, O‐dopedp‐type layers were grown directly on Te‐dopedn‐type solution‐grown (SG) and liquid‐encapsulated Czochralski (LEC) substrates. For SG single‐epitaxy diodes, the quantum efficiencies (&eegr;≃6%) and the other electrical and electroluminescent characteristics are nearly identical to those observed in the previously reported double‐epitaxy diodes, demonstrating that the double‐epitaxy structure is not essential for high efficiencies. For LEC single‐epitaxy diodes, the quantum efficiencies (&eegr;≃2%) establish for the first time the present utility and future potential of LEC crystals in fabricating efficient diodes by single epitaxy.

ISSN:0003-6951    

DOI:10.1063/1.1653072

出版商:AIP    

年代:1970

数据来源: AIP

摘要:

The frequency dependence of the attenuation of acoustic waves in zinc oxide at microwave frequencies was measured using light‐scattering techniques. For a longitudinal wave propagating along thecaxis af2dependence was found and for a shear wave perpendicular to thecaxis the frequency dependence was notf2; the most probable reason being the presence of scattering centers in the crystal.

ISSN:0003-6951    

DOI:10.1063/1.1653073

出版商:AIP    

年代:1970

数据来源: AIP

摘要:

Light absorption by injected holes inn‐type InSb near liquid nitrogen temperature is used to modulate the CO2laser. AP+Njunction device is described which achieves a good modulation efficiency up to a few megahertz with a driving power of 300 mW. Such a modulator can be controlled by applying an external dc magnetic field.

ISSN:0003-6951    

DOI:10.1063/1.1653074

出版商:AIP    

年代:1970

数据来源: AIP

摘要:

A small probe was used to measure the electric field distribution in a 1‐cm‐thick cell containing a nematic liquid crystal. It is found that apart from distances of about 100&mgr; from each electrode, the electric field is quite uniform. The field at the anode is at least ten times higher than the average field. This indicates the existance of space‐charge carriers. The cathode also shows the above effect, but to a much smaller extent. The voltage applied to the cell was varied from 1 ∼ 8 kV. Identical results were obtained for the material in its isotropic state. These measurements give support to the model proposed by Heilmeier to explain dynamic scattering in nematic liquid crystals.

ISSN:0003-6951    

DOI:10.1063/1.1653075

出版商:AIP    

年代:1970

数据来源: AIP

摘要:

Ultraviolet laser radiation at 0.325&mgr; m has been found to produce refractive index increases of up to 3×10−3in poly(methylmethacrylate) and to resolve at least 5000 lines/mm. The index change is tentatively attributed to localized density increases arising from photoinduced cross linking. Applications to optical waveguides and thick dielectric holograms and gratings are described.

ISSN:0003-6951    

DOI:10.1063/1.1653076

出版商:AIP    

年代:1970

数据来源: AIP

摘要:

The drift velocity‐electric field curve for holes inp‐GaAs has been experimentally determined at 300 °K on <111> oriented samples. The velocity becomes a sublinear function of field aroundE=1.5×104V/cm, but no saturation was observed up to the highest fields reached (Emax=6×104V/cm,vmax=7.8×106cm/sec). This result is in disagreement with the recent predictions of Kim based on analysis of GaAs avalanche diode oscillators.

ISSN:0003-6951    

DOI:10.1063/1.1653077

出版商:AIP    

年代:1970

数据来源: AIP

摘要:

A simple pulse measurement is suggested to check whether the switching phenomena in materials and devices is due to double injection. In the Ovshinsky Threshold Switch used in the present measurement, it is found that this model cannot account for the observation. The results seem to support the ``thermal models'' for the initiation of the switching in this device.

ISSN:0003-6951    

DOI:10.1063/1.1653078

出版商:AIP    

年代:1970

数据来源: AIP

摘要:

We propose a method for obtaining the convolution, and correlation, of signals in real time through the nonlinear interaction of two acoustic waves in ferroelectric crystals. The experimental results presented here for the convolution of two 1350‐MHz signals indicate that the strength of the interaction is sufficient to provide new signal processing devices.

ISSN:0003-6951    

DOI:10.1063/1.1653079

出版商:AIP    

年代:1970

数据来源: AIP

摘要:

Using circularly polarized light, high‐quality holograms can be obtained, containing information on the polarization characteristics of the object. A theoretical derivation and some experimental demonstrations are given.

ISSN:0003-6951    

DOI:10.1063/1.1653080

出版商:AIP    

年代:1970

数据来源: AIP

摘要:

A new type of wavelength selector for dye lasers is proposed. It consists of a holographically produced dielectric grating which is backed by a reflecting layer. Gratings of 2300, 3300, and 3700 lines/mm were recorded in dichromated gelatine and tested in an exciplex umbelliferone laser tuning from 3910 to 5670 Å.

ISSN:0003-6951    

DOI:10.1063/1.1653081

出版商:AIP    

年代:1970

数据来源: AIP