A comparison of the water vapor oxidation characteristics AlAs, Al0.98Ga0.02As, and an AlxGa1−xAs digital alloy was performed. The consists periods 49 monolayers AlAs 1 monolayer GaAs has equivalent composition x=0.98. Oxidation rates structural integrity three layers were compared. When oxidized in vapor, have similar rates, both which are twice as fast Al0.98Ga0.02As layer. Post-oxidation annealing these samples at 450 °C showed severe delamination oxide/GaAs interface sample while not damaged.

To determine the prevalence and trends of antiretroviral drug resistance among HIV-1-infected Taiwanese patients who have been provided with free-of-charge therapy (ART) since 1990.Blood samples collected from 786 1999 to 2006 were subjected genotypic assay. Antiretroviral mutations identified in accordance mutation list International AIDS Society-USA Consensus Guidelines. Trends studied enrolled two periods: before (period 1, January December 2003) after 2, 2004 2006) CRF07_BC outbreak...

Abstract Research has shown that spatial perception is not only one of the essential abilities for success in science, technology, engineering, and mathematics (STEM), but also closely related to quality human existence. However, a variety reasons, many students' skills are less than ideal. In recent years, various video games showing great potential as low‐cost effective training tools improve educational level cognitive skills. This paper presented novel serious strategy game named Magic...

We report the development of a low temperature (∼400 °C) and pressure (∼0.5 kg/cm2) spin-on-glass (SOG) wafer bonding technique that can bond compound semiconductors silicon without using chemical-mechanical polishing, surface etching or other intermediate materials in process. The relation quality applied was studied. Cross sectional transmission electron microscopy analysis shows interface is smooth, uniform did not generate dislocations. Using this SOG method, simulated vertical-cavity...

High electron mobility transistor structures containing Inx(AlGa)1−xAs and InxGa1−xAs device layers with X=0.3–0.4 were grown on metamorphic buffer GaAs substrates. The exhibited good flatness a root mean square roughness of 9 Å. Cross-sectional transmission micrographs indicated that the threading dislocations from growth contained in graded layer. For double pulse doped structures, sheet densities up to 4×1012 cm−2 readily achieved. Room temperature mobilities 8600–8800 cm2/V s obtained...

The evolution of the surface morphology InAs nanostructures grown on InGaAs/InP by molecular-beam epitaxy was studied through atomic force microscopy imaging. Randomly distributed quantum dots and wires were reproducibly achieved adjusting proper growth parameters such as deposition thickness, temperature, arsenic overpressure, rate. It is observed that a thick layer, high rate promote formation dots. We propose when deposited, interaction total strain in layer distribution underlying matrix...

Metamorphic heterojunction bipolar transistor (M-HBT) structures and metamorphic P–I–N (M-PIN) photodiode were grown on GaAs substrates. A compositionally graded AlGaInAs buffer layer was used to expand the lattice constant that of InP. Cross-sectional transmission electron micrographs M-HBT structure showed dislocations from compositional grading predominantly localized in device layers possessed planar interfaces. Secondary ion mass spectroscopy depth profiles 4×1019 cm−3 beryllium-doped...

A novel metallic bonding method using AuGeNiCr as the medium was developed for fabrication of long-wavelength vertical-cavity surface-emitting lasers (VCSELs). The process can be performed at a low temperature 320 °C within 1 h and it does not require chemical-mechanical polishing or etching treatments on surfaces. As determined by atomic force microscopy, tolerate surface roughness ∼10 nm samples. Cross-sectional transmission electron microscopy shows that interface is smooth damage-free....

The properties of InAs quantum dots (QDs) deposited on compositionally homogenous and laterally modulated surfaces is investigated by photoluminescence (PL), atomic force microscopy (AFM), transmission electron microscopy. We use solid source molecular beam epitaxy (100)-oriented InP substrates to fabricate the samples. It found that QDs grown a surface are more uniform in size. This implied decrease 22% full width at half maximum (FWHM) PL signal 77 K for as opposed equal monolayer coverage...

The growth parameters of In0.25Ga0.75As grown on GaAs by molecular beam epitaxy were investigated. Low substrate temperatures coupled with lower rates and low arsenic overpressures explored the corresponding threading dislocation densities determined using transmission electron microscopy. Threading in layers much thicker than critical thickness found to be as 1×107 cm−2 optimal conditions. In addition, ternary alloy was estimated. evolution misfit dislocations also examined a function...

Polycrystalline (Ga,As) grown by molecular-beam epitaxy (MBE) is compared to polycrystalline formed annealing amorphous also MBE. Both and materials were at 100 °C crystallinity controlled the As overpressure. material was annealed varying temperatures from 300 500 several properties of changed such as levels excess in material, grain structure strength adhesion crystallized layer, conductivity material. After around 400 °C, specular, polycrystalline, has good adhesion, very conductive....

We propose a method for forming top distributed Bragg reflector (DBR) during very-low temperature (VLT) molecular-beam epitaxy (MBE) growth that is independent of the substrate being used. By varying arsenic overpressure VLT MBE, it was determined by Auger electron spectroscopy and cross-section transmission microscopy alternating layers polycrystalline GaAs amorphous (Al,As) can be deposited. Because these are not single crystal, they grown on any host lattice. After lateral wet oxidation,...

The interface when switching from AlAs to GaAs during solid source molecular-beam epitaxial growth is investigated. conditions for the layers were kept constant except As overpressure. Using a valved cracker cell, we varied V/III flux ratio ∼5.0 ∼25.0. Cross-sectional transmission electron microscopy, photoluminescence spectroscopy, and reflectivity measurements distributed Bragg reflectors indicate that material quality tends improve with increasing dimeric secondary ion mass it shown rough...

Because of its core role in the process tourism, tourism destination has always been focus discussion among industry, but comprehensive evaluation is rarely mentioned. This paper selects as investigation, gives method destination, adapts to trend modernization, and discusses quantifiable model evaluation. first several destinations samples, collects combs information related spatial equity destinations, determines main problem categories destinations. Then, through summary relevant data case...

The strain relaxation in In0.25Ga0.75As and In0.4Ga0.6As grown on GaAs substrates at low temperature has been studied before after laterally oxidizing an underlying Al0.98Ga0.02As layer. as a function of layer thickness measured by cross-sectional transmission electron microscopy x-ray analysis. It is found that oxidation the improves strained InxGa1−xAs Moreover, interfacial misfit dislocations have removed, threading dislocation density decreased approximately one order magnitude oxidation.

Amorphous and polycrystalline compounds of (Ga,As) (Al,As) grown at very low temperatures by molecular-beam epitaxy are characterized. The ultimate microstructure the amount excess arsenic incorporated in or layers found to depend on overpressure during low-temperature growth. With lower overpressure, a structure prevails less is observed inside layer. In contrast, high incorporation achieved high-arsenic overpressures leads formation amorphous films. Upon wet oxidation, lateral oxidation...

Using very-low temperature (VLT) molecular-beam epitaxy (MBE), polycrystalline GaP/Al–oxide distributed Bragg reflectors (DBRs) have been fabricated. The use of high-energy band gap materials, such as GaP, allows for applications in the visible spectrum with minimal absorption photons DBR. Through VLT-MBE and control group-V overpressure, microstructure can be controlled, resulting either amorphous or material. Due to nature material, requirement lattice matching is relaxed no adverse...

A novel metamorphic high electron mobility transistor (HEMT) structure was grown on GaAs substrates by solid-source molecular-beam epitaxy for potential microwave power applications. The HEMT device layers were strain compensated with pseudomorphic (tensile-strained) Al0.3In0.7P donor–barrier and a (compressive-strained) InP channel layer. Atomic force microscopy measurements of the yielded root-mean-square surface roughness 8 Å. Transmission micrographs exhibited flat interfaces dislocation...

Thermal wet oxidations of GaP and Al0.4Ga0.6P at 650 °C for various times have been performed. Comparisons are made on oxidation rates post morphology. Transmission electron microscopy shows that when oxidizing GaP, polycrystalline monoclinic GaPO4⋅2H2O forms without noticeable loss phosphorus. Oxidation 6 h or more leads to poor morphology resulting in cracks detachment. A thickness expansion about 2.5–3 is noticed as a result oxidation. In contrast, oxidized exhibits much better detachment...

Arsenic-doped GaN films and GaNAs have been synthesized by MOCVD. Samples were grown on sapphire, GaN-coated GaAs substrates. Composition, structure, phase distribution characterized EPMA, SIMS, XRD, TEM. The arsenic content increases demonstrably as the growth temperature descreases from 1030 to 700 °C. In high limit, quality arsenic-doped forms sapphire. low regime, nitrogen-rich under some conditions, with a maximum mole fraction of 3%, segregation in form precipitates occurs an increase...

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In this work, the structural, optical, and electrical properties of metamorphic films are examined compared to non-metamorphic films. Results for optical devices presented. Finally reliability HEMTs is examined.

Cu–Pt ordering is studied with cross-sectional transmission electron microscopy in p-type, n-type, and nominally undoped InAlP In(AlGa)P layers. These different doping conditions allow us to investigate the effect of acceptor magnesium donor tellurium on removing In(AlGa)P. Even more significant, however, ability native group III self-diffusion Our data indicate that rapidly diffusing Mg species less effective than relatively slow Te species. Also, our results defects play a important role...

Amorphous and polycrystalline (Ga,P) grown with the molecular beam epitaxy technique at low temperatures were developed as adhesive materials for wafer bonding technology. The microstructure V/III incorporation ratio in studied transmission electron microscopy (TEM) Auger spectroscopy. crystallinity of low-temperature-grown (LTG) (Ga,P), amorphous or polycrystalline, is controlled by phosphorus overpressure during growth. n-type GaP substrates, each LTG material on top, strongly bonded...

High-quality regrowth of InxGa1−xAs and In0.25Al0.75As layers on In0.25Ga0.75As pseudosubstrates was demonstrated. These were formed using lateral oxidation an underlying Al0.98Ga0.02As layer to improve the material quality a relaxed seeding layer. Using transmission electron microscopy, dislocation densities in regrown measured found be equal that (⩽106 cm−2). Doping characterization these films, Hall-effect measurements, also performed for both Si-doped Be-doped materials. The doped films...