摘要:

Post growth thermal annealing has been used to reduce the defect density of GaAs layers grown on Si substrates by molecular beam epitaxy. Transmission electron microscopy indicates a 100× reduction of the true defect density. Twins and stacking faults were eliminated entirely. Most misfit dislocations were confined within the first ∼150 A˚ GaAs layer and formed a regular and narrow network along the Si/GaAs interface. Similar results were obtained from an ion implanted and annealed specimen.

ISSN:0003-6951    

DOI:10.1063/1.98117

出版商:AIP    

年代:1987

数据来源: AIP

摘要:

Photocurrent spectra of GaAs/Al0.38Ga0.62As lattice‐matched superlattice electrodes were obtained in photoelectrochemical cells containing nonaqueous liquid electrolyte; spectra were compared for two electron acceptors, cobalticinium and ferrocinium, having redox potentials (energy levels) that differ by 1.33 V. The spectra were found to be independent of acceptor energy levels, in sharp contrast to previous results with GaAs/GaAs0.5P0.5As strained‐layer superlattices. These results indicate that for lattice‐matched systems hot‐electron transfer from upper quantum states in the quantum wells is not a dominant process. This is explained by the much lower surface trapping rates in lattice‐matched superlattices compared to strained‐layer superlattices.

ISSN:0003-6951    

DOI:10.1063/1.98118

出版商:AIP    

年代:1987

数据来源: AIP

摘要:

We report a detailed study of the effect of lattice mismatch on ZnSe epilayers grown on ⟨001⟩ GaAs by molecular beam epitaxy using photoluminescence (PL), x‐ray diffraction, and transmission electron microscopy (TEM) techniques. We find that our samples are of high quality, exhibiting sharp and strong bound excitons, and that these bound excitons shift to higher energies due to tetragonal distortion as the thickness of the ZnSe epilayer is systematically reduced from ∼1 to 0.1 &mgr;m. Fairly good agreement is found between PL and x‐ray data for the total strain relaxation as a function of layer thickness. TEM measurements are also used to estimate an inelastic component of the strain relaxation in the layers.

ISSN:0003-6951    

DOI:10.1063/1.98119

出版商:AIP    

年代:1987

数据来源: AIP

摘要:

Faulted dipoles in GaAs have been directly imaged by high‐resolution transmission electron microscopy. The dislocation dipoles were introduced into the GaAs by deforming a sample in compression along a ⟨110⟩ axis. Both theZcharacter of the dipole and the intrinsic nature of the stacking faults could be determined directly from the high‐resolution images. Using convergent‐beam electron diffraction, it has been shown that it is possible to determine the polarity of the sample and thereby to differentiate between the &agr; and &bgr; partial dislocations.

ISSN:0003-6951    

DOI:10.1063/1.98120

出版商:AIP    

年代:1987

数据来源: AIP

摘要:

A photoluminescence emission band at 830 nm has been detected in single heterojunction quantum well structures (modulation‐doped structures) in the range of 250–400 K. This emission band is observed neither in heterojunction structures without a two‐dimensional electron gas (2DEG), nor inn+AlGaAs and GaAs. The intensity of the emission band increases as the mobility of the samples with 2DEG and shows excitonic behavior in its variation with incident laser excitation intensity. This photoluminescence emission was observed in samples grown by both molecular beam epitaxy and by organometallic vapor phase epitaxy. This effect may be useful as a rough identification of high quality, modulation‐doped heterostructures.

ISSN:0003-6951    

DOI:10.1063/1.98121

出版商:AIP    

年代:1987

数据来源: AIP

摘要:

Electrons in the electron/hole creation event are shown to be the prime catalytic agent in photon‐stimulated oxidation enhancement of silicon. Oxidation enhancement in the 10–50% range occurs at only moderate power density levels of visible wavelength light and increases greatly for photon energies just exceeding the conduction‐band edge between SiO2and Si. ‘‘Hot’’‐electron injection into the SiO2is thought to enhance the oxidation via a process of electron attachment to some of the in‐diffusing O2species, with subsequent dissociation into O and O−species. This injected hot‐electron flux reaction with O2is thought to also occur at a reduced level during standard thermal oxidation.

ISSN:0003-6951    

DOI:10.1063/1.98126

出版商:AIP    

年代:1987

数据来源: AIP

摘要:

The doping of molecular beam epitaxial GaAs with erbium up to a concentration of 2×1019cm−3has been successfully demonstrated. Up to a concentration of about 5×1018cm−3the surface morphology remained good but for higher doping levels the surface became structured. Hall and profile measurements indicate that erbium doping gives rise to a trapping level capable of compensating silicon‐doped layers. For the first time photoluminescence from a rare earth element incorporated in a III‐V semiconductor has been observed at room temperature.

ISSN:0003-6951    

DOI:10.1063/1.98127

出版商:AIP    

年代:1987

数据来源: AIP

摘要:

Coherence length in a semiconductor induced by the superconductor proximity effect is obtained experimentally from superconducting transition temperature measurements based on the de Gennes–Werthamer–Hauser theory. It was found that the coherence length in the semiconductor increases with increase in the carrier concentrationnas a function ofn1/3. This result agreed with the numerical result derived from the Seto–Van Duzer theory.

ISSN:0003-6951    

DOI:10.1063/1.98129

出版商:AIP    

年代:1987

数据来源: AIP