摘要:

The characteristic properties of noncritically phase‐matched frequency doubling in KTiOPO4have been investigated using ∼1 &mgr;m radiation from a Styryl‐13 dye laser. Noncritically phase‐matched type II second‐harmonic generation was found to occur at 994.3 nm. The unusually wide angle, temperature, and wavelength tolerances observed for this nonlinear process are attractive for the design of practical blue‐green laser sources. A special strained‐layer InGaAs diode laser was fabricated to operate at 994 nm and generation of blue‐green 497 nm radiation by noncritically phase‐matched frequency doubling was demonstrated.

ISSN:0003-6951    

DOI:10.1063/1.102461

出版商:AIP    

年代:1989

数据来源: AIP

摘要:

Laser‐excited stimulated emission is used to detect chlorine atoms in a Cl2/Ar rf etching plasma. Two laser photons near 233.3 nm excite the 3p44p 4S0electronic state of atomic chlorine in a spin‐forbidden transition from the 3p5 2P0ground state. At modest laser fluence stimulated emission is observed from the 3p44p 4S0→3p44s 4Ptransition. The stimulated emission signals are compared to simultaneously acquired laser‐induced fluorescence from the same transition. The strong, collimated stimulated emission provides a means to detect atomic chlorine which only requires a single optical access window.

ISSN:0003-6951    

DOI:10.1063/1.102260

出版商:AIP    

年代:1989

数据来源: AIP

摘要:

Vacuum dehydrogenation of a crystalline phase CrHxCyOzresults in an amorphous phase. The crystalline phase is prepared by electroplating from a cold chromic acid electrolyte with formic acid as additive.

ISSN:0003-6951    

DOI:10.1063/1.102462

出版商:AIP    

年代:1989

数据来源: AIP

摘要:

A simple and fast photothermal measurement system for nondestructive evaluation of coatings is presented. The sample surface is scanned with a focused laser beam and the resulting temperature rise is monitored with a focused infrared detector. The laser light scattered from the sample surface is measured with a photodiode and so both the optical and the thermal image of the sample can be obtained simultaneously. The functionality of the measurement system is demonstrated with two plasma‐spray‐coated samples.

ISSN:0003-6951    

DOI:10.1063/1.101651

出版商:AIP    

年代:1989

数据来源: AIP

摘要:

The influence of the crystallinity of the alignment layers on the electro‐optical behavior of ferroelectric liquid crystals has been quantitatively demonstrated. The degree of crystallization of thin nylon 6.6 alignment layers was varied using thermal anneal methods and determined by Fourier transform infrared spectroscopy. The reaction of an obtained memory state of surface‐stabilized ferroelectric liquid‐crystal samples to small disturbing electric fields decreased when the degree of crystallization of the incorporated nylon 6.6 alignment layers was higher.

ISSN:0003-6951    

DOI:10.1063/1.101652

出版商:AIP    

年代:1989

数据来源: AIP

摘要:

Voids have been found in the near‐surface region of GaAs/AlGaAs superlattices in a transmission electron microscopy study. The superlattices were Si‐ or Al‐implanted and subsequently either furnace or rapid thermally annealed. Concurrent with the presence of voids is an inhibition of superlattice layer intermixing enhancement in the near‐surface region. This inhibition does not occur in the deeper region of the samples where voids are not found. The voids can form via condensation of the Ga and As vacancies produced by the implantation process. We suggest that voids can depress dopant activation, suppress dopant diffusion, and inhibit the superlattice layer intermixing enhancement.

ISSN:0003-6951    

DOI:10.1063/1.101653

出版商:AIP    

年代:1989

数据来源: AIP

摘要:

An analysis of the critical thickness dependence on misfit for epitaxy is presented including effects due to surface stresses. It is shown that these surface stress effects, which have not been included in previous theories of epitaxy, can have a major influence on the critical thickness, especially for relatively large misfits. A simple model incorporating effects due to compressive surface stresses is given which, compared to previous theories, predicts significantly larger (smaller) critical thicknesses when the stress‐free lattice parameter of the film is greater (less) than the lattice parameter of the substrate.

ISSN:0003-6951    

DOI:10.1063/1.101654

出版商:AIP    

年代:1989

数据来源: AIP

摘要:

Rapid thermally annealed silicon‐implantedx‐cut &agr;‐quartz samples have been examined by Rutherford backscattering and Raman microprobe spectroscopy. The data indicate that the silicon has diffused at 1200 °C to form a buried layer of crystallites of size 1–10 &mgr;m. The crystallites are preferentially oriented and under substantial stress.

ISSN:0003-6951    

DOI:10.1063/1.102463

出版商:AIP    

年代:1989

数据来源: AIP

摘要:

A new method for studying the early stages of the growth of oxide epilayers by transmission electron microscopy (TEM) is described. The technique uses well‐characterized, single‐crystal TEM foils as substrates for the deposition process. In the present study, chemical vapor deposition was used to form small islands (50–300 nm) of &agr;‐Fe2O3on (0001) oriented Al2O3thin‐foil substrates. The preferential nucleation of islands at surface steps on the alumina is clearly demonstrated. Selected area diffraction and moire´ fringe pattern analysis are used to show the epitactic nature of the growth and to study the island morphology.

ISSN:0003-6951    

DOI:10.1063/1.102464

出版商:AIP    

年代:1989

数据来源: AIP

摘要:

We report a new effect in which hydrogen‐passivated acceptor impurities inp‐type GaAs are reactivated by low‐intensity, above band gap illumination. Low‐temperature photolumines cence was used to monitor the acceptor reactivation process. The light‐induced reactivation is persistent at cryogenic temperatures, but the material relaxes back to the hydrogen‐passivated state after annealing at moderate temperatures. Preliminary kinetic considerations, as well as the implications of this phenomenon on the fundamental and technological aspects of hydrogen passivation in semiconductors, are briefly discussed.

ISSN:0003-6951    

DOI:10.1063/1.101655

出版商:AIP    

年代:1989

数据来源: AIP