摘要:

Using molecular beam epitaxy assisted by an electron beam irradiation with a beam energy of 50 keV at an angle of incidence 5°, we have successfully grown high quality GaAs layers on untilted (001)Si substrates. Raman spectra show that this technique reduces crystalline imperfections usually found in GaAs layers grown (001)Si substrates by a factor of 20, clearly demonstrating the effectiveness of this technique. Typical low‐temperature photoluminescence spectra of undoped GaAs on Si contain four features at emission energies of 1.503, 1.488, 1.471, and 1.434 eV. The full width at half maximum (FWHM) of the bound excitonic peak with heavy holes is 2.8 meV, which can be one of the narrowest ever reported. The incident electron beam is expected to play several roles, such as cleaning Si surfaces by removing carbon/oxygen residuals, enhancement of migration rates of adatoms on the growing surface, and acceleration of the single‐domain formation during the growth.

ISSN:0003-6951    

DOI:10.1063/1.103899

出版商:AIP    

年代:1990

数据来源: AIP

摘要:

Novel Aharonov–Bohm type electron interferometers are proposed, which have no curved electron waveguide structures to form a ring geometry. But instead the ring geometry is effectively constructed in astraightdouble quantum well structure, by the control of the shapes of the wave functions by electric fields. The interferometer has a perfect single‐mode channel in each arm of the interferometer as well as the exact 1:1 branching ratio to the two arms, for each electron moving in the plane of the ring.

ISSN:0003-6951    

DOI:10.1063/1.103900

出版商:AIP    

年代:1990

数据来源: AIP

摘要:

Using photocurrent spectroscopy, we have studied optical absorption properties of strained InxGa1−xAs/Al0.15Ga0.85As multiple quantum wells grown by molecular beam epitaxy in the presence of electric fields perpendicular to the heterointerface. In the wavelength region where the bulk GaAs substrate is transparent, we observe the quantum confined Stark effect. Optical bistability of a self‐electro‐optic effect device is demonstrated at room temperature without removal of the GaAs substrate.

ISSN:0003-6951    

DOI:10.1063/1.103901

出版商:AIP    

年代:1990

数据来源: AIP

摘要:

The question of whether ionizing radiation creates fixed positive charge and/or neutral hole traps, or simply fills existing neutral hole traps has been examined by equating the density of intrinsic neutral hole traps, present before irradiation, with the sum of fixed positive charge and the remaining neutral hole traps present after x‐ray irradiation. The total number of positive Coulombic and neutral hole traps was found to remain constant, regardless of the level of radiation the device receives. This indicates strongly that fixed positive charge represents filled intrinsic hole traps and that additional hole trapping defects, except for a small amount of fixed negative charge, are not generated by ionizing radiation in the photon energy range studied.

ISSN:0003-6951    

DOI:10.1063/1.104162

出版商:AIP    

年代:1990

数据来源: AIP

摘要:

The epitaxial growth of (100) Cu on (100) Si reported recently using evaporation is analyzed to determine the epitaxial relation between Cu and Si, and also the crystalline quality of the Cu films. A 45° rotation between the (100) plane of Cu and that of Si around their (001) axis is shown to be needed for the lattice match. Such an epitaxial relation is confirmed by the grazing angle x‐ray diffraction, with the [010] of Cu parallel to the [011] of Si. The channeling analysis of a 2‐&mgr;m‐thick Cu film shows a 10% minimum near the surface.

ISSN:0003-6951    

DOI:10.1063/1.103902

出版商:AIP    

年代:1990

数据来源: AIP

摘要:

Much of the technology of our era is based on the SiO2/Si amorphous/crystalline heterojunction interface. Now it appears that As2S3/GaAs amorphous/crystalline heterojunctions show some technological promise. We have found that properly prepared As2S3/GaAs interfaces can have reasonably good electronic quality. The interfacial recombination velocity is ≊15 000 cm/s at flat band, which results in a ∼100‐fold reduction of perimeter recombination currents inp‐njunction mesas. This can be important on heterojunction transistor emitter‐base perimeters, solar cell and light‐emitting diode perimeters, and for reducing mirror facet recombination in semiconductor lasers.

ISSN:0003-6951    

DOI:10.1063/1.104163

出版商:AIP    

年代:1990

数据来源: AIP

摘要:

Long‐range ordering in a (GaP)2/(InP)2short‐period superlattice and a Ga0.525In0.475P buffer layer grown on a (001)GaAs substrate by gas source molecular beam epitaxy were studied. Transmission electron microscopy and low‐temperature cathodoluminesence techniques were used to examine the microstructure of the short‐period superlattice and to determine its band‐gap energy. The superlattice layer was found to have a [001] long‐range ordered structure with a band gap narrowing of about 130 meV, while the Ga0.525In0.475P layer had a 37 meV band‐gap narrowing induced by spontaneous long‐range ordering in the [111] direction. The ordered superlattice layer was found to have a growth‐induced lateral periodic modulation of the composition along the [1¯10] direction. Within the modulating bands, which had a 200 A˚ periodicity, the In composition was found to vary from 42 to 56% while the Ga correspondingly varied between 58 and 44%.

ISSN:0003-6951    

DOI:10.1063/1.103903

出版商:AIP    

年代:1990

数据来源: AIP

摘要:

The strain in a porous Si layer formed by anodization of a crystallinep+‐Si(100) wafer in a HF electrolyte was measured by double‐crystal x‐ray diffractometry. The perpendicular strain in the as‐formed porous Si layer is ∼10−3. The parallel strain is not measurable (<10−4). Upon annealing in vacuum from 200–800 °C, at elevated temperature, the perpendicular strain decreases while the parallel strain remains zero. Subsequently, the perpendicular strain of the annealed sample increases by amounts that depend on the ambient. The observed changes of strain in porous Si layers are explained as being mainly caused by modification of the stress in the native oxide layer due to desorption and absorption of gas. We propose that the strain in porous Si is the net result of stress induced by surface tension, oxide formation, and exchange of gas between the oxide and ambient.

ISSN:0003-6951    

DOI:10.1063/1.103904

出版商:AIP    

年代:1990

数据来源: AIP

摘要:

A comparative study of diluted HF etch rates was performed on thermally grown oxide (1120 °C; O2pressure ≊1.1 atm) and buried oxide layers [formed by implantingn‐andp‐type (100)Si maintained at ≊600 °C with 150–200 keV O+ions to a dose of ≊1.8×1018cm−2, and subsequent annealing at 1250–1325 °C]. From accurate mechanical thickness measurements, a difference in etch rate between thermally grown and buried oxide is observed. This is direct evidence for a structural and/or stoichiometrical difference between both oxides. Additionally, plots of the etch rate as a function of oxide thickness reveal detailed information on the local structure of the oxide layers.

ISSN:0003-6951    

DOI:10.1063/1.103905

出版商:AIP    

年代:1990

数据来源: AIP

摘要:

The depth profiles measured by secondary‐ion mass spectrometry of 56 MeV oxygen ions implanted into Si, GaAs, and InP are reported. Most of the oxygen is contained within a sharp (full width at half maximum ∼2 &mgr;m) non‐Gaussian profile centered at ∼31 &mgr;m in GaAs, ∼36 &mgr;m in InP, and ∼46 &mgr;m in Si, with the distribution skewed towards greater depths. The experimental projected ranges appear to be 10% larger than theoretical predictions. Changes in the electrical, optical, and structural properties of the material were measured by transmission electron microscopy (TEM), photoluminescence, and spreading resistance profiling. In the as‐implanted Si, the maximum perturbation in the electrical properties occurs at ∼37 &mgr;m. No defects are visible by TEM in any of the as‐implanted semiconductors for oxygen ion doses of 1.35×1015cm−2but the photoluminescent intensity in GaAs and InP is reduced by more than an order of magnitude as a result of this type of implantation.

ISSN:0003-6951    

DOI:10.1063/1.103906

出版商:AIP    

年代:1990

数据来源: AIP