Self-diffusion processes in semidilute solutions of nonionic surfactant (C16E7) studied by light scattering and pulsed-gradient spin echo methods

1993 ◽  
Vol 97 (15) ◽  
pp. 3910-3917 ◽  
Author(s):  
Tadashi Kato ◽  
Toshiaki Terao ◽  
Michiko Tsukada ◽  
Tsutomu Seimiya
Keyword(s):  
Light Scattering ◽  
Nonionic Surfactant ◽  
Diffusion Processes ◽  
Spin Echo ◽  
Self Diffusion ◽  
Semidilute Solutions

Pulsed and Steady Field Gradient NMR Diffusion Measurements in Polymers

1985 ◽  
Vol 58 (3) ◽  
pp. 527-560 ◽  
Author(s):  
Ernst D. von Meerwall
Keyword(s):  
Spin Echo ◽  
Concentrated Solutions ◽  
Free Volume Theory ◽  
Polymer Systems ◽  
Polymer Molecules ◽  
Self Diffusion ◽  
Semidilute Solutions ◽  
Nmr Diffusion ◽  
Nmr Methods ◽  
And Diffusion

Abstract Some twenty years after the development of the steady and pulsed gradient spin-echo NMR methods of measuring self-diffusion, these techniques are now maturing and experiencing a surge of interest, much of it concentrated on polymer systems. The methods are briefly reviewed here, together with the most important results in polymers, with particular concentration on work described within the last few years. The research is divisible into three categories: diffusion of diluent and penetrant molecules in rubbery high polymers, diffusion of polymer molecules in dilute and semidilute solutions with liquid solvents, and diffusion of macromolecules dissolved in concentrated solutions or melts of equivalent or different polymers of arbitrary molecular weight. The review includes the main theoretical interpretations of the experiments, particularly the free-volume theory in its various forms and power-law behaviors postulated by recent refinements of tube/reptation and scaling theory. This article represents an updated elaboration of an earlier review.

Diffusion Mechanisms in Sige Alloys

1999 ◽  
Vol 568 ◽  
Author(s):  
Arthur F.W. Willoughby ◽  
Janet M. Bonar ◽  
Andrew D.N. Paine
Keyword(s):  
Diffusion Processes ◽  
Dopant Diffusion ◽  
Elemental Silicon ◽  
Self Diffusion ◽  
Si Substrates ◽  
Marker Layer ◽  
Diffusion Mechanisms ◽  
Silicon And Germanium ◽  
Charged Defects

ABSTRACTInterest in diffusion processes in SiGe alloys arises from their potential in HBT's, HFET's, and optoelectronics devices, where migration over distances as small as a few nanometres can be significant. Successful modelling of these processes requires a much improved understanding of the mechanisms of self- and dopant diffusion in the alloy, although recent progress has been made. It is the purpose of this review to set this in the context of diffusion processes in elemental silicon and germanium, and to identify how this can help to elucidate behaviour in the alloy. Firstly, self diffusion processes are reviewed, from general agreement that self-diffusion in germanium is dominated by neutral and acceptor vacancies, to the position in silicon which is still uncertain. Germanium diffusion in silicon, however, appears to be via both vacancy and interstitial processes, and in the bulk alloy there is evidence for a change in dominant mechanism at around 35 percent germanium. Next, a review of dopant diffusion begins with Sb, which appears to diffuse in germanium by a mechanism similar to self-diffusion, and in silicon via monovacancies also, from marker layer evidence. In SiGe, the effects of composition and strain in epitaxial layers on Si substrates are also consistent with diffusion via vacancies, but questions still remain on the role of charged defects. The use of Sb to monitor vacancy effects such as grown-in defects by low temperature MBE, are discussed. Lastly, progress in assessing the role of vacancies and interstitials in the diffusion of boron is reviewed, which is dominated by interstitials in silicon-rich alloys, but appears to change to domination by vacancies at around 40 percent germanium, although studies in pure germanium are greatly needed.

scholarly journals Self- and Dopant Diffusion in Extrinsic Boron Doped Isotopically Controlled Silicon Multilayer Structures

2002 ◽  
Vol 719 ◽  
Author(s):  
Ian D. Sharp ◽  
Hartmut A. Bracht ◽  
Hughes H. Silvestri ◽  
Samuel P. Nicols ◽  
Jeffrey W. Beeman ◽  
...  
Keyword(s):  
Multilayer Structure ◽  
Secondary Ion Mass Spectrometry ◽  
Diffusion Processes ◽  
Quantitative Description ◽  
Multilayer Structures ◽  
Dopant Diffusion ◽  
Enhanced Diffusion ◽  
Self Diffusion ◽  
Boron Doped ◽  
P Type

AbstractIsotopically controlled silicon multilayer structures were used to measure the enhancement of self- and dopant diffusion in extrinsic boron doped silicon. 30Si was used as a tracer through a multilayer structure of alternating natural Si and enriched 28Si layers. Low energy, high resolution secondary ion mass spectrometry (SIMS) allowed for simultaneous measurement of self- and dopant diffusion profiles of samples annealed at temperatures between 850°C and 1100°C. A specially designed ion-implanted amorphous Si surface layer was used as a dopant source to suppress excess defects in the multilayer structure, thereby eliminating transient enhanced diffusion (TED) behavior. Self- and dopant diffusion coefficients, diffusion mechanisms, and native defect charge states were determined from computer-aided modeling, based on differential equations describing the diffusion processes. We present a quantitative description of B diffusion enhanced self-diffusion in silicon and conclude that the diffusion of both B and Si is mainly mediated by neutral and singly positively charged self-interstitials under p-type doping. No significant contribution of vacancies to either B or Si diffusion is observed.

Measurements of Light Scattering Intensities on Extremely Dilute Solutions of Nonionic Surfactant

Langmuir ◽  
1995 ◽  
Vol 11 (6) ◽  
pp. 1867-1869 ◽  
Author(s):  
Tadashi Kato ◽  
Masaki Kanada ◽  
Tsutomu Seimiya
Keyword(s):  
Light Scattering ◽  
Nonionic Surfactant ◽  
Dilute Solutions
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