Enhanced Carbon Diffusion in Silicon During 900°0 Annealing

1984 ◽  
Vol 36 ◽  
Author(s):  
L. A. Ladd ◽  
J. P. Kalejs ◽  
U. Gösele
Keyword(s):  
Diffusion Coefficient ◽  
Surface Oxidation ◽  
Carbon Diffusion ◽  
Sample Surface ◽  
Carbon Accumulation ◽  
Interstitial Oxygen ◽  
Enhanced Diffusion ◽  
Carbon Precipitation ◽  
High Concentrations

ABSTRACTEnhanced diffusion of carbon Is observed to be produced during anneal ing of silicon at 900°C under conditions of surface oxidation and phosphorus in-diffusion. Silicon containing high concentrations of carbon (∼9 × 1017/cm3 substitutional) and varying levels of interstitial oxygen and differing defect concentrations has been studied. Diffusion coefficient enhancement over the value found for an anneal in an inert ambient is by a factor of three during oxidation and a factor of forty with phosphorus in-diffusion. Carbon accumulation takes place in a region 0.3–0.5 microns from the sample surface only under conditions of phosphorus in-diffusion and is attributed to carbon precipitation. A model that assumes Interactions between silicon self-interstitials and the carbon can explain both the enhanced diffusion and the carbon accumulation.

scholarly journals In-Situ Synchrotron X-ray Diffraction Investigation of Microstructural Evolutions During Low-Pressure Carburizing

2021 ◽  
Author(s):  
Ogün Baris Tapar ◽  
Jérémy Epp ◽  
Matthias Steinbacher ◽  
Jens Gibmeier
Keyword(s):  
Carbon Content ◽  
Carbon Diffusion ◽  
Low Pressure ◽  
Carbon Accumulation ◽  
Experimental Chamber ◽  
Carbide Formation ◽  
X Ray Diffraction ◽  
X Ray ◽  
Carbon Supply

AbstractAn experimental heat treatment chamber and control system were developed to perform in-situ X-ray diffraction experiments during low-pressure carburizing (LPC) processes. Results from the experimental chamber and industrial furnace were compared, and it was proven that the built system is reliable for LPC experiments. In-situ X-ray diffraction investigations during LPC treatment were conducted at the German Electron Synchrotron Facility in Hamburg Germany. During the boost steps, carbon accumulation and carbide formation was observed at the surface. These accumulation and carbide formation decelerated the further carbon diffusion from atmosphere to the sample. In the early minutes of the diffusion steps, it is observed that cementite content continue to increase although there is no presence of gas. This effect is attributed to the high carbon accumulation at the surface during boost steps which acts as a carbon supply. During quenching, martensite at higher temperature had a lower c/a ratio than later formed ones. This difference is credited to the early transformation of austenite regions having lower carbon content. Also, it was noticed that the final carbon content dissolved in martensite reduced compared to carbon in austenite before quenching. This reduction was attributed to the auto-tempering effect.

Diffusion of Zn into Gaas 0.6 P0.4:Te From Zn-Doped Oxide Films By Rapid Thermal Processing

1987 ◽  
Vol 92 ◽  
Author(s):  
A. Usami ◽  
Y. Tokuda ◽  
H. Shiraki ◽  
H. Ueda ◽  
T. Wada ◽  
...  
Keyword(s):  
Diffusion Coefficient ◽  
Thermal Processing ◽  
Rapid Thermal Processing ◽  
Oxide Films ◽  
Zn Diffusion ◽  
Enhanced Diffusion ◽  
Conventional Furnace ◽  
Zn Concentration ◽  
The Difference ◽  
Doped Oxide

ABSTRACTRapid thermal processing using halogen lamps was applied to the diffusion of Zn into GaAs0.6 P0.4:Te from Zn-doped oxide films. The Zn diffusion coefficient of the rapid thermal diffused (RTD) samples at 800°C for 6 s was about two orders of magnitude higher than that of the conventional furnace diffused samples at 800°C for 60 min. The enhanced diffusion of Zn by RTD may be ascribed to the stress field due to the difference in the thermal expansion coefficient between the doped oxide films and GaAs0.6P0.4 materials, and due to the temperature gradient in GaAs0.6P0 4 materials. The Zn diffusion coefficient at Zn concentration of 1.0 × l018 cm−3 was 3.6 × 10−11, 3.1 × 10−11 and 5.0 × 10−12 cm2 /s for the RTD samples at 950°C for 6 s from Zn-, (Zn,Ga)- and (Zn,P)-doped oxide films, respectively. This suggests that Zn diffusibility was controlled by the P in the doped oxide films.

A Calculation Model of Carbon Diffusion Coefficient in the Austenite for Spheroidal Graphite Cast Iron

2014 ◽  
Vol 789 ◽  
pp. 593-598
Author(s):  
Hong Liang Zheng ◽  
Lin Li ◽  
Xin Xin Yuan ◽  
Xue Lei Tian
Keyword(s):  
Diffusion Coefficient ◽  
Cast Iron ◽  
Carbon Content ◽  
Cooling Rate ◽  
Nodular Cast Iron ◽  
Carbon Diffusion ◽  
Calculation Model ◽  
Spheroidal Graphite ◽  
Atom Diffusion ◽  
Graphite Cast Iron

This paper presents the relationship between the carbon atom diffusion coefficient in the austenite and the temperature during the nodular cast iron solidification under different cooling rates or with different carbon contents. Pouring the wedge-shaped casting explores the influence of cooling rate on the diffusion coefficient. The other part explores the change of the diffusion coefficient with different carbon contents by water quenching to save the organization in the solidification. Results show that both the cooling rate and the carbon content can affect the diffusion coefficient, and it decreases as the cooling rate increases. More attempts were also done to correlate the diffusion coefficient with the temperature in different carbon content. It has been found that the diffusion coefficient decreases as the temperature increase.

Enhanced Diffusion in a Model of Molecular Motors with Potential Switching

2019 ◽  
Vol 18 (02) ◽  
pp. 1940005 ◽  
Author(s):  
Ryota Shinagawa ◽  
Kazuo Sasaki
Keyword(s):  
Diffusion Coefficient ◽  
External Force ◽  
Molecular Motors ◽  
Periodic Potential ◽  
Brownian Particle ◽  
Molecular Motor ◽  
Free Diffusion ◽  
Enhanced Diffusion ◽  
Additional Peak ◽  
Diffusion Enhancement

Diffusion enhancement is a phenomenon in which the diffusion coefficient of a system is increased by an external force and it becomes larger than that of the force-free diffusion in thermal equilibrium. It is known that this phenomenon occurs for a Brownian particle in a periodic potential under a constant external force. Recently, it was found that diffusion enhancement also occurred in a biological molecular motor, whose moving part could move itself by switching the potentials generated by the other parts. It was shown that the diffusion coefficient exhibited peaks as a function of a constant external force. Here, we report the occurrence of an additional peak and investigate the condition governing its appearance.

scholarly journals Effect of Lay-Up on the Sorption Behaviour of Woven Glass-Polyester Composites

1998 ◽  
Vol 7 (6) ◽  
pp. 096369359800700
Author(s):  
R. Elleuch ◽  
A. Chateauminois ◽  
Ch. Bradai ◽  
N. Derbel
Keyword(s):  
Numerical Simulation ◽  
Diffusion Coefficient ◽  
Diffusion Rate ◽  
Stratified Media ◽  
Sorption Behaviour ◽  
Enhanced Diffusion ◽  
Linear Behaviour ◽  
Polyester Composites ◽  
Diffusion Behaviour ◽  
Sorption Curve

The effects of the lay-up on the water diffusion behaviour of hand made woven glass/polyester composites have been investigated by means of sorption experiments and numerical simulation of the diffusion process in a stratified media. Experimental sorption curves exhibited a non linear behaviour during the initial sorption step. On the basis of the numerical simulations, this behaviour was attributed to an enhanced diffusion rate in the superficial matrix layers. These effects were found to affect significantly the measurement of the diffusion coefficient from the sorption curve.

What Does Self-Diffusion Tell Us about Ultra Shallow Junctions?

2000 ◽  
Vol 610 ◽  
Author(s):  
Ant Ural ◽  
Serene Koh ◽  
P. B. Griffin ◽  
J. D. Plummer
Keyword(s):  
Point Defects ◽  
High Concentration ◽  
Enhanced Diffusion ◽  
Self Diffusion ◽  
Native Point Defects ◽  
Junction Formation ◽  
Ultra Shallow Junctions ◽  
High Concentrations ◽  
Temperature Furnace ◽  
Dopant Profiles

AbstractUnderstanding the coupling between native point defects and dopants at high concentrations in silicon will be key to ultra shallow junction formation in silicon technology. Other effects, such as transient enhanced diffusion (TED) will become less important. In this paper, we first describe how thermodynamic properties of the two native point defects in silicon, namely vacancies and self-interstitials, have been obtained by studying self-diffusion in isotopically enriched structures. We then discuss what this tells us about dopant diffusion. In particular, we show that the diffusion of high concentration shallow dopant profiles is determined by the competition between the flux of mobile dopants and those of the native point defects. These fluxes are proportional to the interstitial or vacancy components of dopant and self-diffusion, respectively. This is why understanding the microscopic mechanisms of silicon self-diffusion is important in predicting and modeling the diffusion of ultra shallow dopant profiles. As an example, we show experimental data and simulation fits of how these coupling effects play a role in the annealing of shallow BF2 ion implantation profiles. We conclude that relatively low temperature furnace cycles following high temperature rapid thermal anneals (RTA) have a significant effect on the minimum junction depth that can be achieved.

Diffusion Behavior of Carbon Atoms in Austenite Region of SCM435 Steel

2016 ◽  
Vol 850 ◽  
pp. 266-270 ◽  
Author(s):  
Dong Xu ◽  
Bing Zheng ◽  
Xing Liang Gao ◽  
Miao Yong Zhu
Keyword(s):  
Activation Energy ◽  
Diffusion Coefficient ◽  
Arrhenius Equation ◽  
Diffusion Constant ◽  
Carbon Diffusion ◽  
Diffusion Activation Energy ◽  
Diffusion Behavior ◽  
Scm435 Steel ◽  
The Relationship ◽  
Diffusion Activation

The research on the decarbonizing behavior of the austenite region of SCM435 steel was carried out. And the experimental results shewed that the relationship between the diffusion coefficient and temperature totally agreed with the Arrhenius equation and that the diffusion constant and the diffusion activation energy were uniform within the temperature range of 900-1100°C. However, when the austenite reached certain temperature, the carbon diffusion coefficient decreased significantly as temperature increased and its relationship with temperature no longer agreed with the Arrhenius equation.

Boron Segregation and Out-diffusion in Single-Crystal Si 1-y C y

2003 ◽  
Vol 765 ◽  
Author(s):  
E. J. Stewart ◽  
J.C. Sturm
Keyword(s):  
Diffusion Process ◽  
Single Crystal ◽  
Carbon Diffusion ◽  
Subsequent Oxidation ◽  
Boron Segregation ◽  
Carbon Precipitation

AbstractBoron segregation and its effect on carbon diffusion is studied in single-crystal Si1-yCy. We find that boron segregates from silicon to Si0.996C0.004 at a level m=[B]SiC/[B]Si = 1.7 during a 2 hour, 850°Cannealin N2. After this anneal, if most of the carbon is then removed from the Si1-yCy layer (via an oxidation-enhanced out-diffusion process), most of the boron segregation is removed as well. This argues against immobile B-C defects as the predominant mechanism driving the segregation. Boron is shown to increase carbon diffusion during the N2 anneal, but also appears to enhance carbon precipitation during a subsequent oxidation.

scholarly journals Master curve of boosted diffusion for 10 catalytic enzymes

2020 ◽  
Vol 117 (47) ◽  
pp. 29435-29441
Author(s):  
Ah-Young Jee ◽  
Tsvi Tlusty ◽  
Steve Granick
Keyword(s):  
Diffusion Coefficient ◽  
Molecular Motors ◽  
Master Curve ◽  
Turnover Rate ◽  
Gibbs Free Energy Change ◽  
High Turnover ◽  
Enhanced Diffusion ◽  
Catalytically Active ◽  
Instrumental Resolution ◽  
Slow Turnover

Molecular agitation more rapid than thermal Brownian motion is reported for cellular environments, motor proteins, synthetic molecular motors, enzymes, and common chemical reactions, yet that chemical activity coupled to molecular motion contrasts with generations of accumulated knowledge about diffusion at equilibrium. To test the limits of this idea, a critical testbed is the mobility of catalytically active enzymes. Sentiment is divided about the reality of enhanced enzyme diffusion, with evidence for and against. Here a master curve shows that the enzyme diffusion coefficient increases in proportion to the energy release rate—the product of Michaelis-Menten reaction rate and Gibbs free energy change (ΔG)—with a highly satisfactory correlation coefficient of 0.97. For 10 catalytic enzymes (urease, acetylcholinesterase, seven enzymes from the glucose cascade cycle, and one other), our measurements span from a roughly 40% enhanced diffusion coefficient at a high turnover rate and negativeΔGto no enhancement at a slow turnover rate and positiveΔG. Moreover, two independent measures of mobility show consistency, provided that one avoids undesirable fluorescence photophysics. The master curve presented here quantifies the limits of both ideas, that enzymes display enhanced diffusion and that they do not within instrumental resolution, and has possible implications for understanding enzyme mobility in cellular environments. The striking linear dependence of ΔGfor the exergonic enzymes (ΔG<0), together with the vanishing effect for endergonic enzyme (ΔG>0), are consistent with a physical picture in which the mechanism boosting the diffusion is an active one, utilizing the available work from the chemical reaction.

Quantification of Large Scale Micro-X-Ray Fluorescence Elemental Images

2001 ◽  
Vol 55 (11) ◽  
pp. 1448-1454 ◽  
Author(s):  
Christopher G. Worley ◽  
George J. Havrilla ◽  
Paul S. Dunn
Keyword(s):  
Concentration Distribution ◽  
Large Scale ◽  
Surface Oxidation ◽  
Sample Surface ◽  
High Energy ◽  
Depleted Uranium ◽  
Established Method ◽  
X Ray ◽  
Elemental Concentrations ◽  
Relative Differences

Niobium is commonly alloyed with uranium to prevent surface oxidation, and determining how the niobium concentration is distributed throughout a sample is useful in explaining observed material properties. The niobium concentration distribution was determined across the surface of depleted uranium samples using micro-X-ray fluorescence (MXRF). To date, MXRF has been employed primarily as a qualitative tool for determining relative differences in elemental concentrations across a sample surface. Here, a process was developed to convert qualitative MXRF niobium distribution images from depleted uranium samples into images displaying concentration values. Thus, MXRF was utilized to determine elemental concentrations across a surface in a manner similar to that of the established method of electron microprobe X-ray analysis (EMPA). However, MXRF can provide such information from relatively large sample areas many cm2 in size that are too large to examine by the higher spatial resolution technique of EMPA. Although the sample surfaces were polished to the same degree as the standards, little or no sample preparation should be necessary for sample systems where a high energy analyte XRF line can be used for imaging.

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