Self-Diffusion in Compound Semiconductors

1982 ◽  
Vol 14 ◽  
Author(s):  
Arthur F.W. Willoughby
Keyword(s):  
Recent Progress ◽  
Significant Contribution ◽  
Compound Semiconductors ◽  
Device Fabrication ◽  
Self Diffusion ◽  
Diffusion Studies ◽  
Diffusion Mechanisms ◽  
Elemental Semiconductors ◽  
Ion Implanted

ABSTRACTSelf-diffusion studies are vital in the elucidation of atomic mechanisms of diffusion; as well as in the better understanding of device fabrication processes, such as the annealing of ion-implanted layers. This review outlines first the major reasons for interest in self-diffusion in III–V and II–VI compounds. It discusses the main differences with elemental semiconductors, including the wide variety of possible defects in the compounds, the role of departures from stoichiometry, and the value of tracer and interdiffusion studies. Self-diffusion studies in III–V compounds are next reviewed, including recent measurements in GaAs, where more information on diffusion mechanisms is becoming available. Interdiffusion between different III–V compounds is also discussed in the light of self-diffusion studies. Next, recent progress on self-diffusion in certain II–VI compounds is discussed, where interdiffusion studies have also provided a significant contribution. The review concludes by suggesting areas where research is urgently needed to clarify diffusion mechanisms.

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.

Diffusion Modeling of the Redistribution of Ion Implanted Impurities

1985 ◽  
Vol 52 ◽  
Author(s):  
Alwin E. Michel
Keyword(s):  
Thermal Processing ◽  
Rapid Thermal Processing ◽  
Device Fabrication ◽  
Diffusion Modeling ◽  
Enhanced Diffusion ◽  
The Common ◽  
Diffusion Mechanisms ◽  
Silicon Device ◽  
Temperature Furnace ◽  
Ion Implanted

ABSTRACTTransient enhanced diffusion during rapid thermal processing has been reported for most of the common dopants employed for silicon device fabrication. For arsenic a large amount of the available data is fit by a computational model based on accepted diffusion mechanisms. Ion implanted boron on the other hand exhibits anomalous tails and transient motiou. A time dependence of this displacement is demonstrated at lower temperatures. High temperature rapid anneals are shown to reduce some of the anomalous motion observed for low temperature furnace anneals. A model is described that links the electrical activation with the diffusion and describes both the transient diffusion of rapid thermal processing and the large anomalous diffusion reported many years ago for furnace anneals.

Economic Development of Bangladesh: The Role of IBBL

IIUC Studies ◽  
2015 ◽  
Vol 9 ◽  
pp. 323-334
Author(s):  
Shafiqur Rahman ◽  
Nicholas McDonald
Keyword(s):  
Economic Development ◽  
Content Analysis ◽  
Foreign Trade ◽  
Rural Economy ◽  
Significant Contribution ◽  
Annual Report ◽  
Housing Sector

This paper presents the role of Islami Bank Bangladesh Limited (IBBL) to the recent economic development in Bangladesh. The study analyses published texts, articles, websites and annual report of this bank through a content analysis. Key findings of this study manifest the contribution of this bank in different areas of economic development in Bangladesh like generating employment, earning foreign remittance, strengthening rural economy, promoting ecology and green banking, boosting industrialization, developing the SMEs, assisting in foreign trade (import-export), developing the housing sector etc. This study also identifies IBBL’s significant contribution to the national exchequer. This paper contributes to the field of economic development of Bangladesh and the role of IBBL behind it and fills the gap of literature in this specific area.IIUC Studies Vol.9 December 2012: 323-334

Participation of ABCA1 transporter in development of chronic obstructive pulmonary disease

2020 ◽  
Vol 28 (3) ◽  
pp. 360-370
Author(s):  
Stanislav N. Kotlyarov ◽  
Anna A. Kotlyarova
Keyword(s):  
Chronic Obstructive Pulmonary Disease ◽  
Pulmonary Disease ◽  
Significant Contribution ◽  
Modern Medicine ◽  
Lipid Homeostasis ◽  
Chronic Obstructive ◽  
Obstructive Pulmonary Disease ◽  
Reverse Transport ◽  
Current Paradigm

Despite all achievements of the modern medicine, the problem of chronic obstructive pulmonary disease (COPD) does not lose its relevance. The current paradigm suggests a key role of macrophages in inflammation in COPD. Macrophages are known to be heterogeneous in their functions. This heterogeneity is determined by their immunometabolic profile and also by peculiarities of lipid homeostasis of cells. Aim. To analyze the role of the ABCA1 transporter, a member of the ABC A subfamily, in the pathogenesis of COPD. The expression of ABCA1 in lung tissues is on the second place after the liver, which shows the important role of the carrier and of lipid homeostasis in the function of lungs. Analysis of the literature shows that participation of the transporter in inflammation consists in regulation of the content of cholesterol in the lipid rafts of the membranes, in phagocytosis and apoptosis. Conclusion. Through regulation of the process of reverse transport of cholesterol in macrophages of lungs, ABCA1 can change their inflammatory response, which makes a significant contribution to the pathogenesis of COPD.

Role of miRNA in circadian rhythmicity: recent progress

2011 ◽  
Vol 31 (10) ◽  
pp. 1137-1139
Author(s):  
Qing-min WANG ◽  
Hui WAN ◽  
Fen-zhou SHI ◽  
Jun SHEN ◽  
Qiu-hong LIU
Keyword(s):  
Recent Progress ◽  
Circadian Rhythmicity

Recent Progress in the Therapeutic Role of Serelaxin in Vascular Dysfunction

2018 ◽  
Vol 19 (11) ◽  
pp. 1079-1087 ◽  
Author(s):  
Ghulam Murtaza ◽  
Adeel Siddiqui ◽  
Izhar Hussain
Keyword(s):  
Recent Progress ◽  
Vascular Dysfunction ◽  
Therapeutic Role

scholarly journals Emerging Silk Material Trends: Repurposing, Phase Separation and Solution-Based Designs

Materials ◽  
2021 ◽  
Vol 14 (5) ◽  
pp. 1160
Author(s):  
F. Philipp Seib
Keyword(s):  
Phase Separation ◽  
Recent Progress ◽  
Fiber Formation ◽  
Live Cells ◽  
Specific Reference ◽  
New Developments ◽  
Silk Fabrics ◽  
Induced Crystallization ◽  
Liquid Liquid Phase Separation

Silk continues to amaze. This review unravels the most recent progress in silk science, spanning from fundamental insights to medical silks. Key advances in silk flow are examined, with specific reference to the role of metal ions in switching silk from a storage to a spinning state. Orthogonal thermoplastic silk molding is described, as is the transfer of silk flow principles for the triggering of flow-induced crystallization in other non-silk polymers. Other exciting new developments include silk-inspired liquid–liquid phase separation for non-canonical fiber formation and the creation of “silk organelles” in live cells. This review closes by examining the role of silk fabrics in fashioning facemasks in response to the SARS-CoV-2 pandemic.

Tackling Rape Culture in Québec Universities: A Network of Feminist Resistance

2019 ◽  
Vol 25 (11) ◽  
pp. 1290-1308 ◽  
Author(s):  
Sandrine Ricci ◽  
Manon Bergeron
Keyword(s):  
Sexual Violence ◽  
Significant Contribution ◽  
Political Agenda ◽  
The Political ◽  
Feminist Activism ◽  
University Campuses ◽  
Government Institutions ◽  
University Communities ◽  
Dual Perspective

Québec university communities are facing intensified pressure to address the incidence of sexual violence on campus. The ESSIMU ( Enquête Sexualité, Sécurité et Interactions en Milieu Universitaire) survey (2016) revealed that one third of respondents (students and employees from six universities, all genders combined) reported having experienced at least one form of sexual violence since arriving at university, committed by someone affiliated with the same university. As the issue is becoming increasingly institutionalized, a process that often erodes activism, this article highlights the role feminist activism has played in placing sexual violence on university campuses on the political agenda. From the dual perspective of feminist activists and researchers on the ESSIMU team, the article explores the backdrop of this mobilization, and the network of feminist resistance that fostered the ESSIMU study, itself a significant contribution to the increased recognition of sexual violence in universities. It also considers the role of university and government institutions in (re)producing such violence and the role of media in making it a public issue.

Atomistic Modeling of Interfacial Diffusion in the Lamellar Li0 TiAl

1999 ◽  
Vol 578 ◽  
Author(s):  
M. Nomura ◽  
D. E. Luzzi ◽  
V. Vitek
Keyword(s):  
Atomistic Simulation ◽  
Effective Activation Energy ◽  
Surprising Result ◽  
Atomistic Modeling ◽  
Many Body ◽  
Interfacial Diffusion ◽  
Self Diffusion ◽  
Diffusion Mechanisms ◽  
And Migration ◽  
Lamellar Interfaces

AbstractAtomistic simulation employing many-body central-force potentials was performed to elucidate the diffusion mechanisms in the bulk and at lamellar interfaces assuming a vacancy mechanism. First the self- diffusion of Ti and Al in stoichiometric structures was studied. It was found that the diffusion was faster along lamellar interfaces than in the bulk; the effective activation energy for the diffusion coefficient is about ∼15% lower. The simulations were then extended to investigate diffusion along lamellar boundaries with segregated Ti which is likely in Ti rich alloys. The surprising result is that diffusion remains practically unchanged when compared with the stoichiometric case. The reason is that while the path controlling the diffusion is different, the corresponding effective formation and migration energies are practically the same as in the stoichiometric case.

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