Theoretical and Experimental Investigation of Disordering Effects on Photoluminescence Spectra of InGaAs/InGaAsP Quantum Wells

1999 ◽  
Vol 607 ◽  
Author(s):  
J. C. Yi ◽  
W. J. Choi ◽  
S. Lee ◽  
D.H. Woo ◽  
S. H. Kim
Keyword(s):  
Quantum Wells ◽  
Theoretical Calculations ◽  
Diffusion Constant ◽  
Diffusion Time ◽  
Photoluminescence Spectra ◽  
Group Iii ◽  
Diffusion Constants ◽  
Diffusion Temperature ◽  
And Diffusion ◽  
Lattice Matched

AbstractThe effect of disordering on photoluminescence spectra of InGaAs/InGaAsP quantum wells has been investigated experimentally and theoretically taking into account the valence band intermixing, strain, exciton effects, and the non-identical diffusion constants for group III and V materials. The disordering profile of 1.55Q InGaAs/InGaAsP quantum wells lattice matched to InP has been controlled by choice of the cap layer materials as well as the diffusion time and diffusion temperature. By comparing the experimental data and theoretical calculations, the diffusion constant for each material has been extracted.

Effects of diffusion temperature and diffusion time on fabrication of Na-diffused p-type ZnO thin films

2012 ◽  
Vol 80 ◽  
pp. 175-177 ◽  
Author(s):  
Huibin Liu ◽  
Xinhua Pan ◽  
Ping Ding ◽  
Zhizhen Ye ◽  
Haiping He ◽  
...  
Keyword(s):  
Thin Films ◽  
Diffusion Time ◽  
Zno Thin Films ◽  
Diffusion Temperature ◽  
P Type ◽  
And Diffusion

The Distribution Trend of Boron Atoms in Semiconductor Silicon under High Temperature

2021 ◽  
Vol 871 ◽  
pp. 243-247
Author(s):  
Zhi Huan Zhao ◽  
Zhi Bin Zhao ◽  
Ming Ming Jiang ◽  
Chuan Zhong Chen ◽  
Wei Hai Song ◽  
...  
Keyword(s):  
Geometric Model ◽  
Impurity Distribution ◽  
Diffusion Time ◽  
Internal Dynamic ◽  
Diffusion Test ◽  
Hydrodynamic Parameters ◽  
Whole Process ◽  
Diffusion Temperature ◽  
The Relationship ◽  
And Diffusion

The ProENGINEER software is used to build a geometric model for the whole process cavity and internal structure and conduct the internal dynamic simulation of cavity with different diffusion temperatures of 1,000°C, 1,050°C, 1,100°C and 1,150°C, and different diffusion time of 5 min, 10 min, 15 min and 20 min. Analyze the process control indexes by combining with specific thermal diffusion test, and study the relationship between hydrodynamic parameters and diffusion uniformity, Comprehensively investigate the effects of the diffusion temperature and diffusion time on doping, achieving the requirements of impurity distribution in materials.

Highly Strained InAsxPl-X/InP Quantum wells Prepared by Flow Modulation Epitaxy

1989 ◽  
Vol 145 ◽  
Author(s):  
R. P. Schneider ◽  
B. W. Wessels
Keyword(s):  
Quantum Wells ◽  
Atmospheric Pressure ◽  
Growth Conditions ◽  
Photoluminescence Spectra ◽  
Quantum Well Structures ◽  
Flow Modulation ◽  
Modulation Techniques ◽  
Lateral Extent ◽  
Highly Strained ◽  
Lattice Matched

AbstractFlow modulation techniques have been used to prepare highly strained InAsxPl-x/InP quantum well structures in an atmospheric pressure organometallic vapor phase epitaxial reactor. The compositions of the pseudomorphic wells ranged from x=0.40 to 0.74, corresponding to biaxial compressive strains of 1.3-2.4%. Well thicknesses ranged from 2 to 26 monolayers. The flow modulation growth conditions were found to have a strong influence on interface formation in the wells. For wells grown under optimized modulation conditions, low-temperature photoluminescence spectra revealed peak-splitting of the emission from the thinnest wells. This splitting is attributed to emission from regions in the wells with atomically smooth interfaces over areas greater in lateral extent than the exciton diameter. The full-width at half-maximum of the peaks is in the 6-15 meV range, comparable to the best reported values for lattice- matched InGaAs(P)/InP quantum wells grown by any technique, and is independent of well thickness or composition.

Anomalies and regularities in the broadening, shifting, and diffusion of D2 in D2 and D2-He mixtures

2000 ◽  
Vol 78 (5-6) ◽  
pp. 579-598 ◽  
Author(s):  
S H Fakhr-Eslam ◽  
G D Sheldon ◽  
P M Sinclair ◽  
A D May ◽  
J R Drummond
Keyword(s):  
Ab Initio Calculations ◽  
Ab Initio ◽  
Empirical Relation ◽  
Diffusion Constant ◽  
Collision Model ◽  
Diffusion Constants ◽  
Meaningful Comparison ◽  
And Diffusion

Precise and accurate measurements of the Q branch lines of D2 in D2 and D2–He mixtures at several temperatures and low densities reveal a regular broadening at very low densities but only if allowance is made for departures from the soft-collision model. Above about 2 amagat the broadening becomes anomalous and is consistent with earlier observations. Because of the anomalies, a meaningful comparison between broadening and shifting coefficientsand ab initio calculations was not possible. Diffusion constants, as extracted from the data for mixtures, allow us to establish an empirical relation between this diffusion constant and those for pure D2 and for D2 infinitely diluted in He.PACS Nos. 33.70Jg and 33.70-W

Meridional Circulation, Turbulence, and Diffusion Processes in Stars

1976 ◽  
Vol 32 ◽  
pp. 109-116 ◽  
Author(s):  
S. Vauclair
Keyword(s):  
Convection Zone ◽  
Diffusion Processes ◽  
Meridional Circulation ◽  
Diffusion Time ◽  
Work In Progress ◽  
First Results ◽  
Stellar Envelopes ◽  
And Diffusion ◽  
Turbulence And Diffusion ◽  
Hr Diagram

This paper gives the first results of a work in progress, in collaboration with G. Michaud and G. Vauclair. It is a first attempt to compute the effects of meridional circulation and turbulence on diffusion processes in stellar envelopes. Computations have been made for a 2 Mʘstar, which lies in the Am - δ Scuti region of the HR diagram.Let us recall that in Am stars diffusion cannot occur between the two outer convection zones, contrary to what was assumed by Watson (1970, 1971) and Smith (1971), since they are linked by overshooting (Latour, 1972; Toomre et al., 1975). But diffusion may occur at the bottom of the second convection zone. According to Vauclair et al. (1974), the second convection zone, due to He II ionization, disappears after a time equal to the helium diffusion time, and then diffusion may happen at the bottom of the first convection zone, so that the arguments by Watson and Smith are preserved.

scholarly journals Water and Deuterium Oxide Permeability through Aquaporin 1: MD Predictions and Experimental Verification

2007 ◽  
Vol 130 (1) ◽  
pp. 111-116 ◽  
Author(s):  
Artem B. Mamonov ◽  
Rob D. Coalson ◽  
Mark L. Zeidel ◽  
John C. Mathai
Keyword(s):  
Deuterium Oxide ◽  
Diffusion Constant ◽  
Structural Data ◽  
Md Simulations ◽  
Water Model ◽  
Aquaporin 1 ◽  
Self Diffusion ◽  
Osmotic Permeability ◽  
Protein Channels ◽  
And Diffusion

Determining the mechanisms of flux through protein channels requires a combination of structural data, permeability measurement, and molecular dynamics (MD) simulations. To further clarify the mechanism of flux through aquaporin 1 (AQP1), osmotic pf (cm3/s/pore) and diffusion pd (cm3/s/pore) permeability coefficients per pore of H2O and D2O in AQP1 were calculated using MD simulations. We then compared the simulation results with experimental measurements of the osmotic AQP1 permeabilities of H2O and D2O. In this manner we evaluated the ability of MD simulations to predict actual flux results. For the MD simulations, the force field parameters of the D2O model were reparameterized from the TIP3P water model to reproduce the experimentally observed difference in the bulk self diffusion constants of H2O vs. D2O. Two MD systems (one for each solvent) were constructed, each containing explicit palmitoyl-oleoyl-phosphatidyl-ethanolamine (POPE) phospholipid molecules, solvent, and AQP1. It was found that the calculated value of pf for D2O is ∼15% smaller than for H2O. Bovine AQP1 was reconstituted into palmitoyl-oleoyl-phosphatidylcholine (POPC) liposomes, and it was found that the measured macroscopic osmotic permeability coefficient Pf (cm/s) of D2O is ∼21% lower than for H2O. The combined computational and experimental results suggest that deuterium oxide permeability through AQP1 is similar to that of water. The slightly lower observed osmotic permeability of D2O compared to H2O in AQP1 is most likely due to the lower self diffusion constant of D2O.

Diffusion Constant and Diffusion Coefficient

Science ◽  
1955 ◽  
Vol 121 (3137) ◽  
pp. 215-216 ◽  
Author(s):  
J. VERDUIN
Keyword(s):  
Diffusion Coefficient ◽  
Diffusion Constant ◽  
And Diffusion

ULTRACENTRIFUGE AND DIFFUSION STUDIES ON GLUTEN

1942 ◽  
Vol 20c (3) ◽  
pp. 130-159 ◽  
Author(s):  
A. G. McCalla ◽  
Nils Gralén
Keyword(s):  
Sodium Salicylate ◽  
Minimum Weight ◽  
Average Molecular Weight ◽  
Sedimentation Equilibrium ◽  
Velocity Sedimentation ◽  
Molecular Characteristics ◽  
Weight Average Molecular Weight ◽  
Diffusion Constants ◽  
Diffusion Studies ◽  
And Diffusion

The molecular characteristics of gluten in sodium salicylate solutions were studied by means of sedimentation velocity, sedimentation equilibrium, and diffusion measurements. The proportion of total gluten protein molecularly dispersed increased with increase in concentration of sodium salicylate up to 12%, but the dispersed portions had essentially the same sedimentation constant (2.5 ± 0.15) regardless of the concentration of the dispersing medium.The most soluble 25 per cent of the gluten was all molecularly dispersed, but was definitely inhomogeneous. The weight-average molecular weight of this fraction was 44,000, but there is reason to believe the minimum weight may be about 35,000. None of the other fractions was entirely molecularly dispersed, the proportion decreasing with decreasing solubility of the fractions. Aggregates of many sizes existed in all of these fractions, but only the most insoluble contained aggregates large enough to cause opacity. Sedimentation constants of the molecularly dispersed portions increased slightly with decreasing solubility, while diffusion constants decreased markedly. None of the fractions yielded normal curves (diffusion diagrams) but the more soluble the fraction, the more nearly normal the curve. The inhomogeneity responsible for the varying rates of diffusion was due partly to differences in proportion and properties of the molecularly dispersed gluten and partly to aggregates.All properties showed progressive changes both within and between the arbitrarily produced fractions. These results, therefore, support the hypothesis that gluten is a protein system showing progressive and regular changes in properties with change in solubility.

Exciton localization in group-III nitride quantum wells

1999 ◽  
Vol 59 (15) ◽  
pp. 9783-9786 ◽  
Author(s):  
V. I. Litvinov ◽  
M. Razeghi
Keyword(s):  
Quantum Wells ◽  
Group Iii ◽  
Exciton Localization ◽  
Group Iii Nitride
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