摘要:

We report measurements of the polarization and time‐averaged intensity of four‐wave mixing signals from GaAs quantum wells as functions of the pump beam polarizations, laser photon energy, and optical injection density, the latter covering a range of higher levels than has previously been reported. Excitation of heavy‐hole excitons produced a sin2variation of the signal intensity as the pump beam polarizations changed from parallel to perpendicular, while injection of light‐hole excitons led to an approximately cos2dependence. The tuning dependence of the heavy‐hole‐exciton signal revealed a low‐energy signal which is attributed to biexcitons. The dominance of this signal for perpendicular polarization causes the observed sin2variation of the heavy‐hole‐exciton signal. ©1995 American Institute of Physics.

ISSN:0003-6951    

DOI:10.1063/1.114679

出版商:AIP    

年代:1995

数据来源: AIP

摘要:

Buried oxides in silicon‐on‐insulator (SOI) structures have been reported to grow in thickness by thermally oxidizing the superficial silicon layer. A thermodynamic model is presented which is based on the experimental observation that thermal oxidation leads to an increase of the oxygen interstitial concentration in silicon beyond its normal solubility. This increase is assumed to be proportional to the growth rate of the external thermal oxide. Discrepancies between the only two available sets of data are discussed in terms of different levels of oxidation‐induced supersaturations of silicon self‐interstitials. ©1995 American Institute of Physics.

ISSN:0003-6951    

DOI:10.1063/1.114680

出版商:AIP    

年代:1995

数据来源: AIP

摘要:

Insitumolecular beam epitaxy control of III–V optoelectronic device growth has been achieved by dynamic optical reflectometry with tunable excitation wavelength, through the use of a titanium:sapphire laser light source. This new multiwavelength reflectometry method was used to determine the values of the AlAs and GaAs refractive indices at growth temperature (600 °C). Index dispersion between 760 and 960 nm is presented and found to be in good agreement with the existing models. ©1995 American Institute of Physics.

ISSN:0003-6951    

DOI:10.1063/1.114681

出版商:AIP    

年代:1995

数据来源: AIP

摘要:

We report on the polarization independent operation of an electroabsorption guided‐wave modulator based on strained GaInAs–AlInAs multiquantum well structure. The device operates in the 1.5–1.6 &mgr;m wavelength range and exhibits very high static performances as illustrated by the measured 15 dB/100 &mgr;m extinction ratio for a drive voltage of only 1.25 V. We show that the observed polarization insensitivity of this device is in good agreement with the calculation of the electroabsorption curves. The detailed analysis indicates that significant improvement of the performance is still possible. ©1995 American Institute of Physics.

ISSN:0003-6951    

DOI:10.1063/1.114682

出版商:AIP    

年代:1995

数据来源: AIP

摘要:

A new multiquantum well hot‐electron microwave detector is demonstrated. The GaAs–AlGaAs heterostructure was grown by molecular beam epitaxy and tested in theXandKbands. It showed room‐temperature operation with responsivity of several 103 V/W. The operation of the device is based on enhanced thermionic current due to carrier heating by the incident in‐plane polarized microwave electric field. This principle yields a broad frequency range of operation extending up to the millimeter band without significant degradation of the responsivity. ©1995 American Institute of Physics.

ISSN:0003-6951    

DOI:10.1063/1.114683

出版商:AIP    

年代:1995

数据来源: AIP

摘要:

Thin film AlN has been grown on Al2O3and GaAs substrates by metalorganic molecular beam epitaxy using amine bonded alane precursors and either tertiarybutylamine or nitrogen from a compact electron cyclotron resonance (ECR) plasma source operating at 2.45 GHz. Typical growth pressures were in the 0.5–1×10−4Torr range. The growth rates, impurity backgrounds, and surface morphologies were examined for both nitrogen sources and both the solid and liquid alanes. In general, growth efficiencies were good for both alane precursors, allowing for deposition of the low temperature, ∼400 °C, AlN buffers needed for subsequent growth of GaN and InGaAlN alloys. Low growth temperatures could not be obtained using tertiarybutylamine, presumably due to poor decomposition efficiency of the source at low temperatures. The structural quality of material grown at high temperatures from the ECR plasma was measured by atomic force microscopy, high resolution x‐ray diffraction, and transmission electron microscopy, indicating single crystal material with a surface roughness of ∼8 A˚ and an x‐ray full width half‐maximum of 430 arcsec. This ECR plasma‐derived material was of sufficient quality to allow for the growth of multiple quantum well InGaAlN structures. ©1995 American Institute of Physics.

ISSN:0003-6951    

DOI:10.1063/1.114684

出版商:AIP    

年代:1995

数据来源: AIP

摘要:

We report a novel GaAs/InGaAs/GaAs quantum dot structure formed in a tetrahedral‐shaped recess (TSR) patterned on a (111)B GaAs substrate with anisotropic chemical etching. The pseudomorphic heterostructure shows two clear photoluminescence peaks which are attributed to an In anisotropic incorporation on (111)B compared to (111)A. Cathodoluminescence at a lower energy peak with InGaAs of 2.5 nm shows a bright image at the bottom of TSRs which indicates the local minimum in potential energy at the bottom of TSR. ©1995 American Institute of Physics.

ISSN:0003-6951    

DOI:10.1063/1.114685

出版商:AIP    

年代:1995

数据来源: AIP

摘要:

We have produced epitaxialSi1−x−yGexCy/Si heterostructures by rapid thermal chemical vapor deposition using methylsilaneSiCH6). These layers were grown in theSiH4/GeH4/SiCH6/H2system between 550 and 600 °C at 1.5 Torr. Suitable process conditions were found that allow very efficient substitutional carbon incorporation. No carbon cross contamination was observed. Crystal quality, chemical composition, and lattice strain were deduced from Nomarski microscopy, transmission electron microscopy, Fourier transform infrared spectroscopy, secondary ion mass spectrometry, and x‐ray diffraction. Defect‐free alloy layers with compositions of up to 20 at.% Ge and 2.2 at. % C were produced. The lattice parameter was tailored so that the strain in these layers gradually moved from compressive to tensile. A tensile strain of up to 0.35% was achieved. ©1995 American Institute of Physics.

ISSN:0003-6951    

DOI:10.1063/1.114686

出版商:AIP    

年代:1995

数据来源: AIP

摘要:

We report fabrication and electro‐optic measurement of In0.52Al0.48As/In0.53Ga0.47As modulation‐ doped field‐effect transistors. The devices are monolithically integrated with coplanar stripline fixtures incorporating photoconductive switches. The switching time for a 0.35 &mgr;m T‐gate device is 4.2 ps and the delay is 3.2 ps. This is the fastest directly measured switching in a three‐terminal device reported to date. ©1995 American Institute of Physics.

ISSN:0003-6951    

DOI:10.1063/1.114687

出版商:AIP    

年代:1995

数据来源: AIP

摘要:

We investigated the ultrafast energy relaxation of photoexcitedminorityelectrons in highly dopedp‐GaAs by means of femtosecond time resolved luminescence (&Dgr;t<90 fs). Our experiments allow the first observation of the extremely fast cooling of minority electrons within the &Ggr;‐valley. The electron mean energy decreases within 150 fs from 150 meV down to less than 50 meV. The total energy loss rate reaches values higher than 10−7W per electron, representing the highest energy loss rates of electrons observed to date in monocrystalline semiconductors. Ensemble Monte Carlo simulations show that the electron‐hole scattering is responsible for these high energy loss rates. ©1995 American Institute of Physics.

ISSN:0003-6951    

DOI:10.1063/1.114777

出版商:AIP    

年代:1995

数据来源: AIP