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A double heterostructure InGaAsP/InP mesa laser and a mass transport laser were integrated vertically with an InGaAsP/InP double heterojunction bipolar transistor, resulting in the first realization of laser operation in a vertical integration. Laser thresholds as low as 17 mA and an output laser power of over 30 mW were observed. A new type of bistable laser and electro-optical switching were demonstrated. [ABSTRACT FROM AUTHOR]

A tandem combination of a uniform gain broad-area semiconductor laser and a (lateral) periodic gain section displays a stable, near-diffraction-limited single-lobed far-field pattern. The GaAs/GaAlAs quantum well lasers display a high degree of coherence across 60-μm-wide apertures provided that the broad-area section is sufficiently long. [ABSTRACT FROM AUTHOR]

We demonstrate that, as predicted, (Al,Ga)As single quantum well (SQW) lasers have substantially narrower spectral linewidths than bulk double-heterostructure lasers. We have observed a further major reduction (>3×) in the linewidth of these SQW lasers when the facet reflectivities are enhanced. This observation is explained theoretically on the basis of the very low losses in coated SQW lasers and the value of the spontaneous emission factor at low threshold currents. We also report on the modulation frequency response parameter of these SQW lasers. [ABSTRACT FROM AUTHOR]

An InGaAsP/InP superluminescent diode (SLD) emitting at 1.54 μm has been fabricated. The device uses a buried crescent structure on a p-InP substrate. The parameters were optimized for high output power, small spectral modulation, and smooth far-field operation. The coherence function of the SLD emission was studied systematically. An output power of 5 mW, a coherence length of 41 μm, and a second coherence peak suppression ratio of 22 dB were obtained. [ABSTRACT FROM AUTHOR]

The phase evolution with the temperature and time in the process of crystallization of Al[sub 89]La[sub 6]Ni[sub 5] amorphous alloy has been investigated by in situ high-temperature and high-pressure x-ray powder diffraction using synchrotron radiation. Two crystalline phases, fcc-Al and a metastable bcc-(AlNi)[sub 11]La[sub 3]-like phase, were identified after the first crystallization reaction, revealing a eutectic reaction instead of a primary reaction suggested in the literature. Time-dependent nucleation in the amorphous alloy is detected and the experimental data can be fitted by both the Zeldovich’s and Kashchiev’s transient nucleation models with transient nucleation times of 220 and 120 min, respectively. © 2001 American Institute of Physics. [ABSTRACT FROM AUTHOR]

The pressure effect on the crystallization of the Al[sub 89]La[sub 6]Ni[sub 5] amorphous alloy has been investigated by in situ high-pressure and high-temperature x-ray powder diffraction using synchrotron radiation. The amorphous alloy crystallizes in two steps in the pressure range studied (0-4 GPa). The first process, corresponding to simultaneous precipitation of fcc-Al crystals and the metastable bcc-(AlNi)[sub 11]La[sub 3]-like phase, is governed by a eutectic reaction. The second process corresponds to the transformation of a residual amorphous alloy into fcc-Al, Al[sub 11]La[sub 3], Al[sub 3]Ni, and as yet unidentified phase(s). The applied pressure strongly affects the crystallization processes of the amorphous alloy. Both temperatures first decrease with pressure in the pressure range of 0-1 GPa and then increase with pressure up to 4 GPa. The results are discussed with reference to competing processes between the thermodynamic potential barrier and the diffusion activation energy under pressure. © 2000 American Institute of Physics. [ABSTRACT FROM AUTHOR]

We have investigated molecular-beam-epitaxy-grown, pseudomorphic Si[sub 1-y]C[sub y] epilayers (y≤0.015) on Si(001) after ex situ annealing by x-ray scattering at grazing incidence. The diffuse intensity around the Si (220) surface reflection consists of Huang scattering due to the long-range displacement field of substitutional carbon atoms and of the form-factor-induced small angle scattering of holes created by β-SiC precipitates in the Si matrix. Even in the as-grown samples, where other methods gave no indication of β-SiC precipitates, grazing incidence diffraction clearly showed their presence. The precipitates with a mean size of 5 Å are stable against annealing up to at least 600 °C; at 800 °C carbon leaves substitutional sites and the number of precipitates increases, whereas at 1000 °C a significant increase of the precipitate size (up to approx. 15 Å) is detected as well. © 2000 American Institute of Physics. [ABSTRACT FROM AUTHOR]