RHEED Intensity Oscillation Studies of the Kinetics of GaAs Deposition During Chemical Beam Epitaxy(CBE)

1987 ◽  
Vol 102 ◽  
Author(s):  
A. Robertson ◽  
T.H. Chiu ◽  
W.T. Tsang ◽  
J.E. Cunningham
Keyword(s):  
Growth Rate ◽  
Arrival Rate ◽  
Maximum Growth ◽  
Growth Front ◽  
Propagation Mechanism ◽  
Chemical Beam Epitaxy ◽  
Group V ◽  
Partially Saturated ◽  
Kinetics Of

ABSTRACTRecently we have reported the measurement of RHEED intensity oscillations during Chemical Beam Epitaxy(CBE) of GaAs using triethylgallium(TEG) and As2 derived from an arsine cracker(Appl. Phys. Lett. 50(19), May 11,1987). The existence of RHEED intensity oscillations during CBE growth of GaAs indicates that over the range of conditions studied, growth proceeds via nucleation of islands which grow two-dimensionally as opposed to a vicinal step propagation mechanism. In the same study we observed a significant variation of the GaAs growth rate with substrate temperature at constant flux. In addition, the variation of growth rate with incident flux at constant temperature was found to be non-linear below approximately 500°C and linear above 500'C for incident fluxes yielding maximum growth rates between.2 and 1.8 monolayers/sec. Additional measurements of the dependence of the damping of RHEED intensity oscillations on V/11 ratio have indicated much less sensitivity of the growth front morphology to group V flux in CBE. This behavior is thought to reflect the role of highly mobile, partially saturated ethyl-gallium radicals in epitaxial growth by CBE. Measurements of As2 arrival rate limited intensity oscillations on gallium rich surfaces prepared by pyrolyzing TEG in the absence of As2 have shown that the pyrolysis of TEG is not self-limiting at 500°C and that excess gallium can be deposited on gallium rich surfaces. This paper also describes a simple model of the surface pyrolysis of TEG which is consistent with the above experimental observation.

Role of Surface Reconstruction and External Ion Beam in the Growth Kinetics of III-V Molecular Beam Epitaxy

1987 ◽  
Vol 94 ◽  
Author(s):  
S. B. Ogale ◽  
M. Thomsen ◽  
A. Madhukar
Keyword(s):  
Molecular Beam Epitaxy ◽  
Low Temperature ◽  
Surface Reconstruction ◽  
Molecular Beam ◽  
Ion Beam ◽  
Growth Front ◽  
Kinetic Rates ◽  
Kinetics Of ◽  
Low Temperature Epitaxy

ABSTRACTComputer simulations of III-V molecular beam epitaxy (MBE) show that surface reconstruction induced modulation of kinetic rates could give rise to ordering in alloys. Results are also presented for the possible influence of an external ion beam in achieving low temperature epitaxy as well as smoother growth front under usual conditions.

scholarly journals Transformation kinetics of vapor-deposited thin film organic glasses: the role of stability and molecular packing anisotropy

2015 ◽  
Vol 17 (46) ◽  
pp. 31195-31201 ◽  
Author(s):  
Cristian Rodríguez-Tinoco ◽  
Marta Gonzalez-Silveira ◽  
Joan Ràfols-Ribé ◽  
Aitor F. Lopeandía ◽  
Javier Rodríguez-Viejo
Keyword(s):  
Thin Film ◽  
Thermodynamic Stability ◽  
Growth Front ◽  
Molecular Packing ◽  
Front Velocity ◽  
Transformation Kinetics ◽  
Organic Glasses ◽  
Kinetics Of ◽  
Deposition Conditions

The growth front velocity of indomethacin glasses depends on deposition conditions but is not unambigously determined by its thermodynamic stability when the structure is not completely isotropic.

Effect of high salinity on yeast activated sludge reactor operation

2016 ◽  
Vol 74 (9) ◽  
pp. 2124-2134 ◽  
Author(s):  
Matthew Dubois Frigon ◽  
Dongfang Liu
Keyword(s):  
Growth Rate ◽  
Activated Sludge ◽  
High Salinity ◽  
Yeast Species ◽  
Maximum Growth ◽  
Maximum Growth Rate ◽  
Reactor Operation ◽  
Activated Sludge Reactor ◽  
Kinetics Of ◽  
Salinity Wastewater

Yeast activated sludge was developed and operated at salinities of 0, 15, 30, 45, and 60 g/l NaCl. The kinetics of the various sludges degrading a wastewater with glycerol as the carbon source were determined. Inhibition due to salinity was analyzed and it was found that the limiting concentration of NaCl is 120 g/l. Salinity affects the maximum growth rate of the sludge. Reactors were exposed to shock salinity changes. Salt shocks affected maximum growth rate of the reactors but treatment was still effective. The effect of pH adjustment was investigated and it was determined that hourly adjustments of pH led to the most effective treatment outcomes. Finally, DNA of the reactors was investigated. Although Scheffersomyces spartinae (Debaryomycetaceae family) was clearly more suited to the high salinity environment than other yeast species, even at high salinity the number of species was diverse. This suggests the potential to use a number of yeast species for high salinity wastewater treatment.

MBE growth of compound semiconductors: Part II. Applications of the stochastic model

1992 ◽  
Vol 7 (5) ◽  
pp. 1235-1242 ◽  
Author(s):  
R. Venkatasubramanian
Keyword(s):  
Growth Rate ◽  
Surface Roughness ◽  
Phase Separation ◽  
Stochastic Model ◽  
Diffusion Process ◽  
Surface Diffusion ◽  
Growth Front ◽  
Mbe Growth ◽  
Temperature Range ◽  
Kinetics Of

In this part of the work (Part II), two typical applications of the stochastic model to the MBE growth kinetic studies are presented. The applications are the MBE growth kinetics of a hypothetical compound semiconductor, ab, and diamond cubic alloy, ax. In this study, the effect of the surface diffusion process on the MBE growth kinetics is analyzed. In the case of the compound, ab, the results of the present stochastic model are compared with that of a Monte Carlo simulation study in the temperature range of 600–850 K. The results of the two studies agree qualitatively. Higher substrate temperatures result in higher growth rate and growth front smoothness due to higher surface diffusion. Beyond 800 K, the growth rate and the growth front smoothness become independent of temperature because of the saturation of the interlayer diffusion process. In the case of the alloy studies, the kinetics of a hypothetical diamond cubic alloy in which the thermodynamics favors phase separation, is studied in the temperature range of 573–898 K. Below 648 K, due to negligible surface diffusion, there is no clustering of the alloy, but the surface roughness is very large. In the intermediate temperature range of 573–798 K, with increasing temperature, the surface diffusion increases, resulting in more clustering and less surface roughness. Above 798 K, due to very high surface diffusion, complete phase separation of the alloy and a smooth surface result.

Updraft/Downdraft Constraints for Moist Baroclinic Modes and Their Implications for the Short-Wave Cutoff and Maximum Growth Rate

2005 ◽  
Vol 62 (12) ◽  
pp. 4450-4458 ◽  
Author(s):  
Pablo Zurita-Gotor
Keyword(s):  
Growth Rate ◽  
Vertical Structure ◽  
Baroclinic Instability ◽  
Maximum Growth ◽  
Static Stability ◽  
Short Wave ◽  
Maximum Growth Rate ◽  
Unstable Solutions ◽  
Baroclinic Modes

Abstract This paper examines the dynamics of moist baroclinic modes, based on the idealized model of moist baroclinic instability devised by Emanuel et al. These authors found that the finite static stability along the downdraft prevents the explosive short-wave cyclogenesis of the zero stratification limit in the moist problem, and allows only moderate (order 2) changes in the growth rate and short-wave cutoff, even when the moist static stability vanishes. To understand the limiting role of the dry static stability, a constraint is derived in this paper that relates the updraft and downdraft structures. This constraint is based on continuity and implies that a bulk wavenumber (defined in the paper) scales as the relevant deformation radius in each region. Because neutral solutions are separable, the vertical structure can be encapsulated in terms of a single, equivalent wavenumber based on the downdraft width. This allows an interpretation of the results in terms of the equivalent dry mode. As the ratio between moist and dry static stability decreases, the downdraft width takes an increasingly larger fraction of the total wavelength. In the limit of moist neutrality all the wavelength is occupied by the downdraft, so that the short-wave cutoff is halved. The vertical phase tilt makes unstable solutions nonseparable, and prevents defining an equivalent wavenumber in that case. However, the constraint between the bulk wavenumbers still applies. As the moist stability is reduced, the updraft solution becomes more suboptimal; in the limit of moist neutrality, the updraft wavenumber equals the short-wave cutoff. This provides a bound to the maximum growth rate in the moist problem, which is in agreement with the results of Emanuel et al.

scholarly journals Mechanism of Electromigration Failure in Al Thin Film Interconnects Containing Sc

1995 ◽  
Vol 391 ◽  
Author(s):  
Choong-Un Kim ◽  
S. H. Kang ◽  
F.Y. Génin ◽  
J. W. Morris
Keyword(s):  
Thin Film ◽  
Growth Rate ◽  
Grain Growth ◽  
Annealing Time ◽  
Grain Refiner ◽  
Rate Of Evolution ◽  
Failure Statistics ◽  
Al Thin Film ◽  
Kinetics Of

AbstractIn order to understand the role of Sc on electromigration (EM) failure, Al interconnects with 0.1 and 0.3 wt.% Sc were tested as a function of post-pattern annealing time. In response to the evolution of the line structure, the statistics of lifetime evolved. While the addition of Sc greatly reduces the rate of evolution of the failure statistics because the grain growth rate decreases, the MTF variation was found to be very similar to that of pure Al. These observations seem to show that Sc has little influence on the kinetics of Al EM; however, it has some influence on the EM resistance of the line since it is an efficient grain refiner. Unlike Cu in Al, Sc does not seem to migrate, which may explain its lack of influence on the kinetics of Al EM.

Investigation of the Mechanism and Growth Kinetics of Homoepitaxial 4H-SiC Growth Using CH3Cl Carbon Precursor

2006 ◽  
Vol 527-529 ◽  
pp. 171-174 ◽  
Author(s):  
Huang De Lin ◽  
Jeffery L. Wyatt ◽  
Yaroslav Koshka
Keyword(s):  
Growth Rate ◽  
Gas Flow ◽  
Linear Trend ◽  
Maximum Growth ◽  
Maximum Growth Rate ◽  
Gas Flow Rate ◽  
Flow Conditions ◽  
Precursor Decomposition ◽  
Carrier Gas Flow ◽  
Kinetics Of

In this work, the mechanism of the epitaxial growth of 4H SiC using CH3Cl as the carbon source gas was investigated. The experiments were conducted with a H2 carrier gas flow rate reduced in comparison to the standard conditions used for device-quality, full-wafer C3H8 growth. Low-H2 conditions have been found favorable for investigating the differences between the two gas systems. A non-linear trend of the growth rate dependence on CH3Cl flow was observed. This dependence was quantitatively different for C3H8 growth, which serves as an indication of different kinetics of CH3Cl and C3H8 precursor decomposition, as well as differences in Si droplet formation and dissociation. The maximum growth rate that we were able to achieve was by a factor of two higher for the CH3Cl precursor than for the C3H8 precursor at the same temperature and flow conditions. The growth on lower off-axis angle substrates produced surface morphology degradation similar for both CH3Cl and C3H8 precursor systems.

Anoxic control of odour and corrosion from sewer networks

2004 ◽  
Vol 50 (4) ◽  
pp. 341-349 ◽  
Author(s):  
W. Yang ◽  
J. Vollertsen ◽  
T. Hvitved-Jacobsen
Keyword(s):  
Growth Rate ◽  
Respiration Rate ◽  
Maximum Growth ◽  
Maximum Growth Rate ◽  
Endogenous Respiration ◽  
Batch Reactors ◽  
Fundamental Knowledge ◽  
Basic Understanding ◽  
Kinetics Of ◽  
Sewer Networks

Anoxic processes can effectively control odour and corrosion in sewer networks. However, the absence of fundamental knowledge on the kinetics of anoxic transformation of sewage prevents the engineering applications of anoxic control in sewers. This paper focuss on a basic understanding of the anoxic transformations needed for a conceptual simulation of the water phase processes. Experiments conducted in batch reactors have shown that nitrite builds up in wastewater during denitrification. Part of the nitrate-reducing biomass is capable of utilizing nitrite after nitrate is depleted. Compared with aerobic transformation, anoxic processes have low values of maximum growth rate of the biomass and also a low endogenous respiration rate. Heterotrophic yield determined under anoxic conditions, at level of 0.25 mmol e-eq (mmol e-eq)-1, accounted for less than 40% of the corresponding aerobic values.

scholarly journals THE KINETICS BOTH OF GROWTH AND METABOLITE PRODUCTION OF X.CAMPESTRIS USING OF 4% LIQUID SUGAR SUBSTRATE FROM CASSAVA HYDROLISATE

2017 ◽  
Vol 6 (1) ◽  
pp. 45-49
Author(s):  
Nancy Siti Djenar ◽  
Edi Wahyu Sri Mulyono
Keyword(s):  
Growth Rate ◽  
Xanthan Gum ◽  
Maximum Growth ◽  
Process Conditions ◽  
Metabolite Production ◽  
Method Of Calculation ◽  
Cell Weight ◽  
Dry Cell Weight ◽  
Kinetics Of ◽  
Dry Cell

X. campestris is aerobic bacteria producing extracellular biopolymers (EPS, extracellular polysaccharide) known as xanthan gum. To determine the technology and the process conditions appropriate to the formation of this product, therefore the understanding of both the kinetics of growth and metabolite production of bacteria is needed. In this research, to assess the growth of X. campestris using the method of calculation of dry cell weight. For determining the kinetics of production of metabolite used substrates of 4% liquid sugar from cassava starch hydrolysate. From this research was showed that X. campestris maximum growth in NB medium obtained in about 58thhour, at the growth rate of about 0.04 g / hour, stationary phase obtained at the 60th hour with a maximum dry cell weight of 2.7688 g/L and specific growth rate (?) of X. campestris amounted to 0.043 hour-1. Based on the kinetic curves both on growth and its metabolite production, X.campestris has non-growth associated product pattern. In this case the production of xanthan gum occured after cell growth stopped then its product is a secondary metabolite with highest amount of 3.73 g / L at 102nd hour, ie the 4th day of fermentation. Overall of this research indicated that Nutrient Broth (NB) may be used for the growth of X. campestris. But based on the value of ? above, the rate of cell reproduction was still low. Liquid sugar can be used as a substrate to produce xanthan gum. However to increase its productivity, there should be an addition of other carbon or energy and nitrogen sources.

Defects in Photo-Assisted CBE-Grown GaAs

1992 ◽  
Vol 282 ◽  
Author(s):  
Peter J. Goodhew ◽  
R. Beanland ◽  
T. Farrell
Keyword(s):  
Electron Microscopy ◽  
Growth Rate ◽  
Excimer Laser ◽  
Secondary Electron ◽  
Laser Light ◽  
Maximum Growth ◽  
Maximum Growth Rate ◽  
Chemical Beam Epitaxy ◽  
High Fluence ◽  
Microstructure Of The Material

ABSTRACTExcimer laser light has been used to achieve the maximum growth rate of GaAs in a chemical beam epitaxy system when temperatures were more than a hundred degrees below the normalgrowth temperature. Secondary electron and transmitted electron microscopy of material grown using laser assistance shows the presence of surface ripples aligned with crystallographic directions. Layers grown at the lowest temperatures using a high fluence of excimer laser light contain a high density of small dislocation tangles (>1011 cm-−2 ). Lower fluences have no effect on the microstructure of the material.

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