LPCVD of Silicon Nitride Films From Hexachlorodisilane and Ammonia

1987 ◽  
Vol 105 ◽  
Author(s):  
R. C. Taylor ◽  
B. A. Scot
Keyword(s):  
Activation Energy ◽  
Growth Rate ◽  
Silicon Nitride ◽  
Physical Properties ◽  
Growth Rates ◽  
Rate Data ◽  
Kcal Mole ◽  
Silicon Nitride Films ◽  
Kinetically Controlled ◽  
Controlled Deposition

AbstractHexachlorodisilane (Si2Cl6) has been used as an alternative to dichlorosilane and silane for growth of silicon nitride films. The films were grown at a pressure of 0.7 Torr at temperatures between 450° and 850°C. Growth rate data indicates a kinetically controlled deposition with an activation energy of 29.3 kcal/mole. Growth rates are substantially higher than those obtained from SiH2Cl2 under similar conditions, and the physical properties of the films are essentially the same. At the higher growth temperatures stoichiometric Si3N4 films with no detectable chlorine can be obtained when a NH3/Si2Cl6 ratio of 60 or greater is used.

Vulcanization of Elastomers. 23. The Chemical Kinetics of Vulcanization Reactions and The Physical Properties of The Vulcanizates. I

1960 ◽  
Vol 33 (2) ◽  
pp. 335-341
Author(s):  
Walter Scheele ◽  
Karl-Heinz Hillmer
Keyword(s):  
Activation Energy ◽  
Physical Properties ◽  
Chemical Kinetics ◽  
Kcal Mole ◽  
First Order ◽  
Equilibrium Swelling ◽  
Kinetics Of ◽  
Kinetics Of Vulcanization ◽  
Limiting Value ◽  
Good Agreement

Abstract As a complement to earlier investigations, and in order to examine more closely the connection between the chemical kinetics and the changes with vulcanization time of the physical properties in the case of vulcanization reactions, we used thiuram vulcanizations as an example, and concerned ourselves with the dependence of stress values (moduli) at different degrees of elongation and different vulcanization temperatures. We found: 1. Stress values attain a limiting value, dependent on the degree of elongation, but independent of the vulcanization temperature at constant elongation. 2. The rise in stress values with the vulcanization time is characterized by an initial delay, which, however, is practically nonexistent at higher temperatures. 3. The kinetics of the increase in stress values with vulcanization time are both qualitatively and quantitatively in accord with the dependence of the reciprocal equilibrium swelling on the vulcanization time; both processes, after a retardation, go according to the first order law and at the same rate. 4. From the temperature dependence of the rate constants of reciprocal equilibrium swelling, as well as of the increase in stress, an activation energy of 22 kcal/mole can be calculated, in good agreement with the activation energy of dithiocarbamate formation in thiuram vulcanizations.

Chemical control of physical properties in silicon nitride films

2012 ◽  
Vol 111 (3) ◽  
pp. 867-876 ◽  
Author(s):  
Xiangdong Xu ◽  
Dong Zhou ◽  
Qiong He ◽  
Yadong Jiang ◽  
Taijun Fan ◽  
...  
Keyword(s):  
Silicon Nitride ◽  
Physical Properties ◽  
Chemical Control ◽  
Silicon Nitride Films

Homoepitaxial Growth Rate Studies on Diamond (110), (111), and (100) Surfaces in a Hot-Filament Reactor

1992 ◽  
Vol 270 ◽  
Author(s):  
C. Judith Chu ◽  
Benjamin J. Bai ◽  
Norma J. Komplin ◽  
Donald E. Patterson ◽  
Mark P. D'evelyn ◽  
...  
Keyword(s):  
Growth Rate ◽  
Substrate Temperature ◽  
Growth Rates ◽  
Radical Mechanism ◽  
Effective Activation ◽  
Methyl Radical ◽  
Kcal Mole ◽  
Hot Filament ◽  
Substrate Temperatures ◽  
Methane Concentrations

ABSTRACTGrowth rates of homoepitaxial (110), (111), and (100) diamond films were experimentally determined, for the first time, in a hot filament reactor using methane and carbon tetrachloride as the carbon source. Methane concentrations from 0.07 % to 1.03 % in H2 were studied at a substrate temperature of 970°C. Growth rates were found to be crystal-face dependent with respect to methane concentration, being linear or first order for the (100)-orientation, sublinear for (110), and sigmoidal for (111). The observed growth kinetics of (111) suggest the viability of an acetylene mechanism for (111), along with the methyl radical mechanism at methane concentrations above 0.73%. CC14 concentrations from 0.06% to 0.69% in H2 were also investigated at a substrate temperature of 970°C. Growth rate behavior was similar to that of methane for all three crystal faces.The temperature dependence of the growth rates was also crystal-orientation dependent. At substrate temperatures above 730°C, growth rates are thought to be mainly transport limited, yielding effective activation energies of 8±3, 18±2, and 12±4 kcal/mole for (100), (110), and (111) orientations, respectively. At substrate temperatures below 730°C, growth rates are thought to be surface reaction rate-limited, with an overall effective activation energy of 50±19 kcal/mole for the three crystal-orientations studied.

scholarly journals Characteristic Growth Processes of Ice Crystals on the Antarctic Ice Sheet

1988 ◽  
Vol 11 ◽  
pp. 104-108 ◽  
Author(s):  
Hiroshi Nishimura ◽  
Norikazu Maeno
Keyword(s):  
Activation Energy ◽  
Growth Rate ◽  
Temperature Gradient ◽  
Apparent Activation Energy ◽  
Temperature Dependence ◽  
Growth Rates ◽  
Ice Crystals ◽  
Gradient Layer ◽  
Isothermal Layer ◽  
Characteristic Growth

Characteristic growth processes were investigated by measuring cross-sectional areas of ice crystals for four 30 m snow cores drilled in Mizuho Plateau, Antarctica. Considerable difference was found in the growth rate of crystals between a temperature-gradient layer above 6 m depth and an isothermal layer below 10 m depth: the growth rate in the temperature-gradient layer was much larger than that in the isothermal layer. In the isothermal layer, temperature dependence of the growth rate K was expressed by an equation K = K 0 exp(−E/RT), where R and T are the gas constant and absolute temperature respectively. The apparent activation energy E is 44.7 kJ mol−1. On the other hand, in the temperature-gradient layer, the apparent activation energy was as small as 12 kJ mol−1: the difference was explained as due to the temperature gradient. Using the temperature profiles in snow that have been estimated from the meteorological data from several stations, the growth rates in the temperature-gradient layer were calculated. The calculated temperature dependence of the growth rates, taking into consideration vertical flux of water vapor between ice particles caused by the temperature gradient, showed good agreement with measured results. It is concluded that the growth process in the layer above 6 m depth is mainly due to vapor transport under the vertical temperature gradient.

Ultrathin Nitride Films Grown Under Low-Energy Ion Bombardment

1993 ◽  
Vol 316 ◽  
Author(s):  
Zhong-Min Ren ◽  
Zhi-Feng Ying ◽  
Xia-Xing Xiong ◽  
Mao-Qi He ◽  
Yuan-Cheng DU ◽  
...  
Keyword(s):  
Activation Energy ◽  
Silicon Nitride ◽  
Substrate Temperature ◽  
Photoelectron Spectroscopy ◽  
Ion Beam ◽  
Atomic Ratio ◽  
Low Energy ◽  
Ion Energy ◽  
Silicon Nitride Films ◽  
Thermal Nitridation

ABSTRACTBombardment of silicon surfaces by low-energy nitrogen ions has been investigated as a possible process for growing films of silicon nitride at relatively low temperature(<500°C). Broad ion beams of energy 300–1200eV have been used to grow ultrathin silicon nitride films. Film thickness and chemical states are analyzed using ellipsometery, X-ray photoelectron spectroscopy (XPS), and Auger electron spectroscopy(AES). As a result, thicknesses dependence on ion energy, substrate temperature and implantation time have been investigated. The thicknesses of films obtained appear to increase with ion energy in the range from 300 to 1200eV, and with time of bombardment. The thicknesses are also observed to vary slightly with substrate temperature. The growth mechanism has also been investigated and discussed. The average activation energy of nitridation rates is about 3.5meV which indicates nonthermal process kinetics, compared to an activation energy of 0.2–0.6eV for thermal nitridation. AES results show that the atomic ratio [N]/[Si] is about 1.5, larger than that of pure Si3N4. All the analyses show that silicon nitride films of about 60Å thickness have been grown on silicon by low-energy ion beam nitridation.

scholarly journals Effect of frequency of pasture measurement on estimation of pasture growth rates: field observations and predictions of a whole farm model

2002 ◽  
pp. 91-95
Author(s):  
W.E. Prewer ◽  
J.A. Lile ◽  
K.A. Macdonald ◽  
K.P. Bright ◽  
C.C. Palliser ◽  
...  
Keyword(s):  
Growth Rate ◽  
Growth Rates ◽  
Human Error ◽  
Climatic Factors ◽  
Dairy Farm ◽  
Visual Assessment ◽  
Accurate Estimate ◽  
Rate Data ◽  
Mass Model ◽  
Farm Model

The frequency of measurements to generate pasture growth rate data varies. Commonly measurements are made once weekly or fortnightly and averaged monthly, using a variety of methods. To assess the effect of frequency of measurement on estimates of pasture growth rate, weekly visual assessment of farm pasture cover was compared with the fortnightly and monthly average and also with predictions by a Whole Farm Model. Weekly observed pasture growth rates had large fluctuations but these were removed when the weekly values were averaged monthly. The fluctuations are due to the variety of paddocks assessed, climatic factors, inconsistencies of operators and inherent errors in the technique used. Values calculated by a Whole Farm Model also showed daily variation in pasture growth rate but the fluctuations were not as severe as those in the observed pasture growth rate data because human error of assessment and error in the technique were removed. Observed monthly pasture growth rates were also compared with values calculated by the model. The model closely predicted observed pasture growth rates for most months. To obtain an accurate estimate for monthly growth rates it is better to average a number of assessments. In the field, this could be an average of weekly observations. Because the model calculates rates daily, it can be used to predict pasture growth rates on a more frequent basis (e.g. weekly) to aid feed budgeting. Keywords: dairy farm, herbage mass, model, pasture growth, simulation

THE REACTION OF CYCLOPENTANE VAPOR WITH Hg 6(3P1) ATOMS AT ELEVATED TEMPERATURES: THE RECOMBINATION, DISPROPORTIONATION, AND DECOMPOSITION OF CYCLOPENTYL RADICALS

1964 ◽  
Vol 42 (2) ◽  
pp. 357-370 ◽  
Author(s):  
Harry E. Gunning ◽  
Richard L. Stock
Keyword(s):  
Activation Energy ◽  
Thermal Decomposition ◽  
Elevated Temperatures ◽  
Arrhenius Plot ◽  
New Products ◽  
Reaction Vessel ◽  
Rate Data ◽  
Kcal Mole ◽  
Low Light ◽  
Ethylene Propylene

The static reaction of Hg 6(3P1) atoms with cyclopentane vapor (c-C5H10) has been studied with temperatures from 26 to 376°, at constant c-C5H10 concentration and at low light intensities.From 26 to 250°, the only important products are hydrogen, cyclopentene, and bicyclopentyl. Above 250° new products appearing are ethylene, biallyl, and allyl cyclopentane, together with smaller yields of propylene, ethane, propane, and methane. To 250°, the reaction can be explained in terms of a 5-step paraffinic sequence, involving initial C—H scission to form H atoms and cyclopentyl (c-C5H9) radicals. The Arrhenius plot of a function equal to kdisp/kcomb for c-C5H9 radicals showed that Edisp−Ecomb = 0. Above 250° c-C5H9 radicals decompose into C2H4 and C3H5 radicals. The activation energy for this process was determined from a number of product functions to be 36.9 ± 1.2 kcal/mole. Evidence was also found for scission of c-C5H9 into cyclopentene and H atoms, above ca. 300°.A brief examination was also made of the thermal decomposition of c-C5H10 up to 457° in a quartz reaction vessel. The substrate is unstable above 350° forming ethylene, propylene, cyclopentene, cyclopentadiene, and hydrogen. The rate data can be satisfactorily explained by two intramolecular decompositions of the substrate into (a) ethylene and propylene and (b) cyclopentene and hydrogen with the cyclopentene further dehydrogenating to cyclopentadiene. From the data Ea = 49.6 ± 2.0 kcal/mole and Eb = 44.0 ± 2.0 kcal/mole.

An Investigation of the Effects of Microstructure on Fatigue Crack Growth in Ti-6242

2005 ◽  
Vol 127 (1) ◽  
pp. 46-57 ◽  
Author(s):  
F. McBagonluri ◽  
E. Akpan ◽  
C. Mercer ◽  
W. Shen ◽  
W. O. Soboyejo
Keyword(s):  
Growth Rate ◽  
Fatigue Crack ◽  
Crack Growth Rate ◽  
Fatigue Crack Growth ◽  
Crack Growth ◽  
Growth Rates ◽  
Surface Crack ◽  
Rate Data ◽  
Aspect Ratios ◽  
Crack Growth Rates

Surface and subsurface crack nucleation and growth mechanisms are elucidated for equiaxed (microstructure 1), elongated (microstructure 2), and colony (microstructure 3) microstructures of Ti6242. Prominent cleavage facets, indicative of a Stroh-type dislocation-pile phenomenon characterize the nucleation sites. Beachmarking and scanning electron microscopy (SEM) techniques are used to study fatigue crack growth rates and crack shape evolution in the short and long crack regimes. The studies reveal that surface crack growth rate data are generally comparable to the through-crack growth rate data in the long crack growth regime. However, the depth crack growth rates are somewhat slower than the through-crack growth rates. Surface crack evolution profiles are shown to exhibit a tendency towards “Preferred Propagation Paths” (PPPs). However, the magnitudes of the aspect ratios along the PPPs are different from those reported for square or rectangular cross sections subjected to cyclic tension or bending loads. Finally, the measured crack lengths and aspect ratios are compared with predictions obtained from a fracture mechanics model.

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