摘要:

The temperature‐dependent performance of low‐voltage asymmetric Fabry–Perot transverse modulators is studied. While the heavy hole exciton moves with a rate of 2.4 A˚/°C, the Fabry–Perot mode shifts with a rate three times slower, 0.8 A˚/°C. This can provide a large and nearly constant value of reflection modulation (∼13%/V) over a relatively wide (15 °C) temperature range, as compared to more simple transverse absorption modulators. However, the contrast ratio varies from 15 to 3.5.

ISSN:0003-6951    

DOI:10.1063/1.103710

出版商:AIP    

年代:1990

数据来源: AIP

摘要:

We describe a technique for controllably etching nanometer size features into Si(100) and GaAs(100) surfaces with the scanning tunneling microscope while under a (0.05%) HF solution which dissolves oxides. The etching mechanism appears to be due to a field‐induced oxide growth followed by a chemical etching of the oxide. With this technique, we can etch features as small as 20 nm in linewidth.

ISSN:0003-6951    

DOI:10.1063/1.103711

出版商:AIP    

年代:1990

数据来源: AIP

摘要:

Rapid thermal processing chemical vapor deposition was employed for selective epitaxial growth of silicon. Defect‐free epitaxial islands were grown into oxide windows with ⟨110⟩ sidewall orientation on (100) silicon substrates. The effects of growth temperature on the degree of faceting have been studied. The hydrogen prebake temperatures as low as 1000 °C have proven to be sufficient for high quality Si deposition without sidewall oxide undercutting.

ISSN:0003-6951    

DOI:10.1063/1.103712

出版商:AIP    

年代:1990

数据来源: AIP

摘要:

We interpret published depth profiles of deuterium inn‐ andp‐type GaAs, following long anneals at 500 °C in a gaseous deuterium atmosphere, as indicating the indiffusion of a native defect (probably VAs) and an impurity (possibly O), both tagged with deuterium. Model fits yield the 500 °C diffusivity of the tagged impurity as 4×10−14cm2/s and the diffusivities of the tagged native defect as 3×10−15cm2/s inn‐GaAs and ∼8×10−15cm2/s inp‐GaAs.

ISSN:0003-6951    

DOI:10.1063/1.103713

出版商:AIP    

年代:1990

数据来源: AIP

摘要:

The decomposition of trimethylgallium (TMGa) on the gallium‐rich (4×6) and (1×6) GaAs (100) surface was studied with temperature programmed desorption, Auger electron spectroscopy, and low‐energy electron diffraction. TMGa was found to dissociatively chemisorb on the gallium‐rich surfaces, apparently at the gallium vacancies that exist on these surfaces. We have unambiguously identified methyl radicals desorbing from the surface with the maximum rate at ∼440 °C following a saturation TMGa exposure. Since TMGa was shown to decompose on the clean, gallium‐rich GaAs (100) surfaces, the self‐limiting deposition of gallium during atomic layer epitaxy must be due to the presence of surface methyl groups which inhibit further TMGa dissociative chemisorption.

ISSN:0003-6951    

DOI:10.1063/1.103714

出版商:AIP    

年代:1990

数据来源: AIP

摘要:

We investigate the structure of the conduction minibands in a two‐dimensional periodic array of rectangular quantum wires. The finite barrier height in such a GaAs/Ga1−xAlxAs heterostructure gives rise to a ‘‘checker‐board’’ pattern of wells and barriers, i.e., a checker‐board superlattice (CBSL). The energy bands are obtained using the finite element method, in the effective mass approximation, with current continuity at interfaces. The free‐carrier‐induced optical nonlinear susceptibility &khgr;(3)due to band nonparabolicity in the CBSL is obtained in both the rectangular directions. Our calculations predict an increase in &khgr;(3)of about 1–2 orders of magnitude over bulk GaAs, for specific ranges of carrier concentrations.

ISSN:0003-6951    

DOI:10.1063/1.103715

出版商:AIP    

年代:1990

数据来源: AIP

摘要:

The beam propagation method has been applied to find confined energy eigenvalues and eigenfunctions for a III‐V quantum well structure subjected to an external electric field. Quantum‐confined Stark shifts for both electrons and holes and excitonic states for single and double quantum wells are calculated. Excellent agreement with analytical results where available is demonstrated. A comparison with experimental data published in the literature is given.

ISSN:0003-6951    

DOI:10.1063/1.104106

出版商:AIP    

年代:1990

数据来源: AIP

摘要:

In this letter, we address the effectiveness of patterned growth in reducing defect density in GaAs on Si. Defect reduction is considered to be subject to the effect of edge profile and the density of defects in initial GaAs islands. Pattern edges (mask edges or large steps) are often the sites for generating microtwins/stacking faults. Mutual interaction of dislocations inhibits the gliding of dislocations to pattern edges, thus affecting the effectiveness of patterned growth in improving the epilayer quality. The study also shows that surface orientation influences the formation of misfit dislocations with a preferred Burgers vector. This observation is interpreted by considering the variation of misfit with different lattice planes across the interface between Si and ‘‘tilted’’ GaAs lattices.

ISSN:0003-6951    

DOI:10.1063/1.103716

出版商:AIP    

年代:1990

数据来源: AIP

摘要:

We describe the use of accumulation layers of electron charge in applications as magnetoresistive devices. We consider two such systems: an InGaAs/InP heterostructure in which we identify a two‐dimensional electron gas from the observation of the quantum Hall effect, and InAs films, in which a strong surface accumulation of charge is inferred from depth profiling studies of the galvanomagnetic coefficients. Magnetoresistive devices fabricated from these materials exhibit outstanding field sensitivity and temperature stability due to the existence of electrons of relatively high density and mobility in the accumulation regions. We also model the magnetosensitivity of our devices.

ISSN:0003-6951    

DOI:10.1063/1.103717

出版商:AIP    

年代:1990

数据来源: AIP

摘要:

Hole concentrations in excess of 1020cm−3have been achieved in AlxGa1−xAs using carbon doping during metalorganic molecular beam epitaxy. Hall and secondary‐ion mass spectrometry measurements show a 1:1 correspondence between the hole density and carbon concentration in as‐grown samples, although post‐growth annealing at 900 °C leads to a reduction in the net free‐carrier concentration (typically a decrease of ∼40% for 30 s anneals). The carbon‐localized vibrational modes (LVMs) show fine structure due to the presence of three different symmetries for substitutional carbon CAs, namelyTd, C2v, and C3v. The experimental CAsLVM line positions are in remarkable agreement with the predictions of a rigid ion model.

ISSN:0003-6951    

DOI:10.1063/1.103718

出版商:AIP    

年代:1990

数据来源: AIP