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Presents a study which examined the extent of relaxation and orientation of linearly graded In[subx]Al[sub1-x]As buffers grown on gallium arsenide using a novel x-ray diffraction reciprocal-space mapping technique. Theoretical background; Description of the experimental setup; Results.

Presents a study which examined the effects of built-in biaxial strain on Γ-X transport in GaAs/InxAl[sub1-x]As/GaAs pseudomophic heterojunction barier structures. Experimental details; Theoretical methods; Conclusion.

We demonstrate lasing action in a novel microcavity laser device based on vertical cavity surface-emitting laser technology. This laser can be used for intracavity spectroscopy, high contrast imaging of small (10 μm) structures, and is well suited for use in micro-optical mechanical systems for analysis of particles or fluids. Here, we investigate spectra of intracavity polystyrene spheres. Lasing threshold, single-mode operation, and multimode operation are all studied. Transverse mode separation in the multimode regime is found to be effective for sizing of the spheres. [ABSTRACT FROM AUTHOR]

We report significant differences between the properties of buried oxides converted from AlGaAs and AlAs layers using selective wet oxidation. Layers of AlxGa1-xAs with x≥0.96 exhibit crystallographic dependent oxidation rates, while for layers with x≤0.92 the oxidation rate is isotropic. Mesas containing partially oxidized layers of AlAs are unstable to rapid thermal cycling and exhibit excessive strain at the oxide terminus, while mesas containing partially oxidized layers of AlGaAs are robust and lack evidence of strain. Finally, the oxidation of AlGaAs layers, rather than AlAs, is found to provide robust oxide apertures for reliable vertical-cavity surface emitting lasers. © 1996 American Institute of Physics. [ABSTRACT FROM AUTHOR]

We have quantified unintentional indium incorporation in GaAs grown by molecular beam epitaxy in a variety of commercial systems. We find that the unintentional indium density in the epitaxial GaAs is more a function of mounting technique and prior machine history than of the manufacturer’s design. The indium densities detected in the epitaxial GaAs for substrates that only partially obscure an indium-bearing mount are equal to levels reported to result in minimum defect densities and narrowest photoluminescence linewidths in In-doped GaAs. [ABSTRACT FROM AUTHOR]

We report dramatic improvements to the implanted-planar buried-heterostructure graded-index separate confinement heterostructure (IPBH-GRINSCH) laser in (AlGa)As/GaAs which produces low threshold current, continuous-wave operation. Our process features significantly reduced fabrication complexity of high quality, index-guided laser diodes compared to regrowth techniques and, in contrast to diffusion-induced disordering, allows creation of self-aligned, buried, blocking junctions by ion implantation. The improved single-stripe IPBH-GRINSCH lasers exhibit 39 mA threshold current, cw operation. [ABSTRACT FROM AUTHOR]

We report measurements of the injection-locking characteristics of a high-power continuous-wave diode laser array with an on-chip independently controlled master laser. This integrated injection-locked array emits a near-diffraction-limited single-lobed output beam at cw power levels up to 220 mW/facet. By controlling the current to the master laser, the single-lobed output beam can be electronically steered over a far-field angle of >1.7°. We also report preliminary studies of the coupling interaction in these integrated devices. [ABSTRACT FROM AUTHOR]

The geometry of quantum well surface-emitting lasers has several important consequences. The ultrashort (∼1 μm) vertical cavity defines longitudinal modes with energy separation greater than the bandwidth of spectral gain. The optical confinement of these modes can approach unity. To achieve lasing, high carrier densities (∼1012 cm-2) in the quantum well are required. The confined carriers interact through enhanced many-body exchange which influences both the lasing wavelength and threshold characteristics. Indeed, the exchange interaction can facilitate the lasing process. We theoretically and experimentally study the role of the short cavity and exchange interaction on the cw lasing threshold as a function of temperature. In constrast to edge emitters, the lasing threshold in these surface emitters exhibits a well-defined minimum at a particular temperature. The temperature of the minimum can be designed by merely changing the active layer thickness. [ABSTRACT FROM AUTHOR]

We describe a simple, new method for deducing surface alloy composition during ternary III/V molecular beam epitaxy. The method is based on on-line reflection mass spectrometry of the group V flux ‘‘reflected’’ from the surface during momentary terminations of individual group III fluxes. [ABSTRACT FROM AUTHOR]

We report the first integrated injection-locked high-power continuous-wave diode laser array with an on-chip independently controlled master laser. This device emits a near-diffraction-limited (0.5° full width at half maximum) single-lobed far-field emission beam at single-facet powers up to 125 mW. Also, by current tuning the emission wavelength of the master laser, we observe steering of the single-lobed emission over an angular range of 0.50° at a rate of -1.2×10-2 deg/mA. Our work demonstrates the feasibility of incorporating active optical injection and control in the structure of high-power diode laser devices. [ABSTRACT FROM AUTHOR]

We report room-temperature, continuous-wave (cw), photopumped operation of (Al,Ga)As surface-emitting lasers grown by molecular beam epitaxy. These monolithic semiconductor lasers comprise two multilayer semiconductor mirrors surrounding a layered active region. In the active region, GaAs quantum wells are spaced with half-wave periodicity to center on standing-wave maxima of the cavity optical field. By comparing threshold data for different lasers grown with and without half-wave periodicity, we observe the first experimental evidence for reduced cw lasing threshold (as low as 2×104 W/cm2 ) with periodic gain in an epitaxial surface-emitting laser. Up to 50 mW with high efficiency (35% total, 80% differential) and narrow spectral linewidth (2 Å) have been measured. A very high quality beam with low divergence (2.5°) and circular TEM00 profile has been observed. All of these observations represent significant advances for surface-emitting laser technology. [ABSTRACT FROM AUTHOR]

A novel surface-emitting semiconductor laser with a vertical resonator, extremely short gain length, and enhanced gain at a specific design wavelength has been demonstrated. The gain medium consists of a series of GaAs quantum wells separated by AlGaAs spacers whose thicknesses are chosen to be one-half the wavelength of a particular transition in the quantum wells. This structure forces the antinodes of the standing-wave optical field to coincide with the gain elements, enhancing the gain and frequency selectivity in the vertical direction and substantially reducing amplified spontaneous emission. We have achieved optically pumped lasing with a threshold of 6 MW/cm2 at room temperature in a molecular beam epitaxially grown structure of thickness 4.3 μm, of which only 320 nm provided gain. [ABSTRACT FROM AUTHOR]

An apertured and cryoshrouded mass spectrometer, which measures line-of-sight molecular fluxes from the surface, has been incorporated into a GaAs molecular beam epitaxy system. The spectrometer is simple to implement, yet is a powerful real-time growth diagnostic. We have used the spectrometer to measure transient and steady-state As incorporation from As4 during bilayer-by-bilayer growth of GaAs. We find, interestingly, that (1) the incorporation coefficient does not oscillate significantly; (2) transient incorporation coefficients depend on surface reconstruction, and may be higher than 0.5 at high Ga fluxes; and (3) in the absence of a Ga flux, excess Ga on the surface need not imply an incorporation coefficient of 0.5. [ABSTRACT FROM AUTHOR]

An air-stable electronic surface passivation for GaAs and other III-V compound semiconductors that employs sulfur and a suitable metal ion, e.g., Zn, and that is robust towards plasma dielectric deposition has been developed. Initial improvements in photoluminescence are twice that of S-only treatments and have been preserved for >11 months with SiO[sub x]N[sub y] dielectric encapsulation. Photoluminescence and x-ray photoelectron spectroscopies indicate that the passivation consists of two major components with one being stable for >2 years in air. This process improves heterojunction bipolar transistor current gain for both large and small area devices. © 2000 American Institute of Physics. [ABSTRACT FROM AUTHOR]

InGaAs multiple quantum wells at 1.3 μm wavelength have been grown on a twist-bonded GaAs compliant substrate. The GaAs compliant substrate contains a 30 Å GaAs thin layer bonded to a GaAs bulk substrate with a 22-degree angle. Nomarski phase contrast microscopy, transmission electron microscopy (TEM), and photoluminescence were used to characterize the heteroepitaxial layers. The smooth and crosshatch-free surface morphology, dislocation-free cross-sectional TEM, and strong luminescence intensity all provide convincing evidences for substantial improvement of the quality of heteroepitaxial material using the compliant substrate technique. Research is underway to apply the concept and technique of compliant substrate to Si and other materials. © 1998 American Institute of Physics. [ABSTRACT FROM AUTHOR]

Presents a corrected version of the article, entitled 'Surface-emitting, multiple quantum wells GaAs/AlGaAs laser with wavelength-resonant periodic gain medium,' by M.Y.A. Raja, S.R.J. Brueck, M. Osinski, C.F. Schaus, J.G. McInerney, T.M. Brennan and B.E. Hammons, published in the volume 53 of the 'Applied Physics Letters' journal.