Kinetically controlled superstructural phases at the Sb/Si (5 5 12) interface

2005 ◽  
Vol 891 ◽  
Author(s):  
Mahesh Kumar ◽  
Vinod Kumar Paliwal ◽  
Govind ◽  
A. G. Vedeshwar ◽  
S. M. Shivaprasad
Keyword(s):  
Surface Characterization ◽  
Room Temperature ◽  
Dominant Role ◽  
High Index ◽  
Adsorption And Desorption ◽  
Different Temperatures ◽  
Low Energy Electron ◽  
Electron Energy Loss

ABSTRACTThe adsorption of Sb on the high index Si (5 5 12) has been studied at higher substrate temperature (HT) (800°C), using in situ surface characterization techniques like Auger Electron Spectroscopy (AES), Low Energy Electron Diffraction (LEED), and Electron Energy Loss Spectroscopy (EELS). The surface morphology of this high index Si (5 5 12) surface has row like trenches along (110) direction. We have performed the study of Sb adsorption and desorption on the Si (5 5 12) substrate held at different temperatures. The different pathways adopted during adsorption and desorption have suggested the dominant role of kinetics I forming various surface phases on the Si (5 5 12) substrate. The adsorption at room temperature resulted in the formation of (225) surface phase, while the adsorption at 680°C resulted in the (337) phase. The sequential thermal desorption of the room temperature and high temperature adsorbed surface resulted in the formation of (337) phases at 800°C, with anisotropic growth along one direction. While the adsorption at 800°C resulted in the formation of anisotropic (337) like phases, the further increase in the coverage formed a 2x Si (225) phase. Annealing this 2x Si (225) phase again resulted in the formation of anisotropic (337) phase. Thus formation of interface by controlling the growth kinetics can result in the formation of various tailored structures with desired properties.

scholarly journals The Vulnerability of Vessels Involved in the Role of Embolism and Hypoperfusion in the Mechanisms of Ischemic Cerebrovascular Diseases

2016 ◽  
Vol 2016 ◽  
pp. 1-11 ◽  
Author(s):  
Yong Peng Yu ◽  
Lan Tan
Keyword(s):  
Cerebral Infarction ◽  
Dominant Role ◽  
Cerebrovascular Diseases ◽  
Effective Care ◽  
Cerebrovascular Events ◽  
Accurate Definition ◽  
Ischemic Cerebrovascular Diseases ◽  
Vascular Stenosis

Accurate definition and better understanding of the mechanisms of stroke are crucial as this will guide the effective care and therapy. In this paper, we review the previous basic and clinical researches on the causes or mechanisms of ischemic cerebrovascular diseases (ICVD) and interpret the correlation between embolism and hypoperfusion based on vascular stenosis and arterial intimal lesions. It was suggested that if there is no embolus (dynamic or in situ emboli), there might be no cerebral infarction. Three kinds of different clinical outcomes of TIA were theoretically interpreted based on its mechanisms. We suppose that there is a correlation between embolism and hypoperfusion, and which mechanisms (hypoperfusion or hypoperfusion induced microemboli) playing the dominant role in each type of ICVD depends on the unique background of arterial intimal lesions (the vulnerability of vessels). That is to say, the vulnerability of vessels is involved in the role of embolism and hypoperfusion in the mechanisms of ischemic cerebrovascular diseases. This inference might enrich and provide better understandings for the underlying etiologies of ischemic cerebrovascular events.

Study of scalable IBS nanopatterning mechanisms for III-V semiconductors using in-situ surface characterization

2011 ◽  
Vol 1354 ◽  
Author(s):  
Jean Paul Allain ◽  
Osman El-Atwani ◽  
Alex Cimaroli ◽  
Daniel L. Rokusek ◽  
Sami Ortoleva ◽  
...  
Keyword(s):  
Surface Chemistry ◽  
Surface Characterization ◽  
Ion Irradiation ◽  
Ion Beam ◽  
Low Energy ◽  
Self Organization ◽  
Beam Parameter ◽  
Ion Beam Sputtering

ABSTRACTIon-beam sputtering (IBS) has been studied as a means for scalable, mask-less nanopatterning of surfaces. Patterning at the nanoscale has been achieved for numerous types of materials including: semiconductors, metals and insulators. Although much work has been focused on tailoring nanopatterning by systematic ion-beam parameter manipulation, limited work has addressed elucidating on the underlying mechanisms for self-organization of multi-component surfaces. In particular there has been little attention to correlate the surface chemistry variation during ion irradiation with the evolution of surface morphology and nanoscale self-organization. Moreover the role of surface impurities on patterning is not well known and characterization during the time-scale of modification remains challenging. This work summarizes an in-situ approach to characterize the evolution of surface chemistry during irradiation and its correlation to surface nanopatterning for a variety of multi-components surfaces. The work highlights the importance and role of surface impurities in nanopatterning of a surface during low-energy ion irradiation. In particular, it shows the importance of irradiation-driven mechanisms in GaSb(100) nanopatterning by low-energy ions and how the study of these systems can be impacted by oxide formation.

The role of platinum on the NOx storage and desorption behavior of ceria: An online FT-IR study combined with in situ Raman and UV-Vis spectroscopy

2020 ◽  
Author(s):  
Anastasia Filtschew ◽  
Pablo Beato ◽  
Søren Birk Rasmussen ◽  
Christian Hess
Keyword(s):  
Gas Phase ◽  
Phase Analysis ◽  
Room Temperature ◽  
Storage Mechanism ◽  
In Situ Raman ◽  
Vis Spectroscopy ◽  
Ft Ir ◽  
Ir Study

The role of platinum on the room temperature NOx storage mechanism and the NOx desorption behavior of ceria was investigated by combining online FT-IR gas-phase analysis with in situ Raman...

The role of structural and fluidic aspects of room temperature ionic liquids in influencing the morphology of CdSe nano/microstructures grown in situ

2014 ◽  
Vol 43 (31) ◽  
pp. 11843-11854 ◽  
Author(s):  
Apurav Guleria ◽  
Ajay K. Singh ◽  
Madhab C. Rath ◽  
Sisir K. Sarkar ◽  
Soumyakanti Adhikari
Keyword(s):  
Ionic Liquids ◽  
Room Temperature ◽  
Cdse Nanoparticles ◽  
Multiple Roles ◽  
Room Temperature Ionic Liquids ◽  
Intrinsic Structure

Influence of the intrinsic structure of RTIL on the morphology of as synthesized CdSe nanoparticles is demonstrated. IL plays multiple roles,i.e.as a solvent, stabilizer and shape directing template.

The growth of AuGa2 thin films on GaAs(001) to form chemically unreactive interfaces

1986 ◽  
Vol 1 (4) ◽  
pp. 537-542 ◽  
Author(s):  
Jeffrey R. Lince ◽  
Tsai C. Thomas ◽  
Williams R. Stanley
Keyword(s):  
Electron Spectroscopy ◽  
Auger Electron ◽  
Room Temperature ◽  
Substrate Surface ◽  
Film Deposition ◽  
X Ray ◽  
Low Energy Electron Diffraction ◽  
Interface Roughening ◽  
Low Energy Electron ◽  
Electron Energy Loss

Thin AuGa2 films were grown by codeposition from separate Au and Ga evaporation sources on clean GaAs(001) substrates in ultrahigh vacuum, and were studied by Auger electron spectroscopy, electron energy-loss spectroscopy, low-energy electron diffraction, scanning electron microscopy, and x-ray diffractometry. The morphology and crystallinity of the AuGa2 were highly dependent upon the film deposition and annealing history. Films grown on room-temperature substrates were continuous, specular, and polycrystalline, but the dominant orientation was with the (001) planes of the crystallites parallel to the substrate surface. Annealing to temperatures between 300°and 480°C caused the film to break up and coalesce into rectangular crystallites, which were all oriented with (001) parallel to the surface. An anneal to 500°C, which is above the AuGa2 melting point, resulted in the formation of irregular polycrystalline islands of AuGa2 on the GaAs(001) substrate. No interface roughening or chemical reactions between the film and substrate or interface were observed for even the highest-temperature anneals.

Positronium Lifetimes and Gas Permeation in Aquivion® for Fuel Cells

2012 ◽  
Vol 733 ◽  
pp. 61-64 ◽  
Author(s):  
Hamdy F.M. Mohamed ◽  
Yoshinori Kobayashi ◽  
Seiichi Kuroda ◽  
Akihiro Ohira
Keyword(s):  
Fuel Cells ◽  
Relative Humidity ◽  
Free Volume ◽  
Room Temperature ◽  
Gas Permeability ◽  
Gas Permeation ◽  
Positronium Lifetime ◽  
Different Temperatures ◽  
Linear Correlations

Variations of ortho-positronium (o-Ps) lifetime and gas permeability of the Aquivion® E8705 membrane were studied as functions of temperature under vacuum and relative humidity at room temperature. When the temperature was varied between 0 and 100 °C in vacuum, the hole volume of Aquivion® E8705, deduced from the ortho-positronium lifetime, gradually increased. However, when the relative humidity was changed at room temperature, the hole volume was essentially unchanged. Good linear correlations between the logarithm of permeabilities of O2 and H2 and reciprocal hole volume at different temperatures indicates the importance role of free volume in gas permeation in dry Aquivion® E8705. However, for hydrated Aquivion® E8705 the permeability less depends on hole volume.

Room Temperature Nitridation and Oxidation of Si, Ge and Mbegrown Sige Using Low Energy Ion Beams (0.1-1 Kev).

1991 ◽  
Vol 223 ◽  
Author(s):  
O. Vancauwenberghe ◽  
O. C. Hellman ◽  
N. Herbots ◽  
J. L. Olson ◽  
W. J. Tan ◽  
...  
Keyword(s):  
Room Temperature ◽  
Ion Beam ◽  
Film Properties ◽  
Dielectric Thin Films ◽  
Ion Energy ◽  
Insulating Films ◽  
Ion Energies ◽  
Energy Dependent

ABSTRACTDirect Ion Beam Nitridation (IBN) and Oxidation (IBO) of Si, Ge, and Si0.8Ge0.2 were investigated at room temperature as a function of ion energy. The ion energies were selected between 100 eV and 1 keV to establish the role of energy on phase formation and film properties. Si0.8Ge0.2 films were grown by MBE on Si (100) and transferred in UHV to the ion beam processing chamber. The modification of composition and chemical binding was measured as a function of ion beam exposure by in situ XPS analysis. The samples were nitridized or oxidized using until the N or O 1s signal reached saturation for ion doses between 5×1016 to 1×1017 ions/cm2. Combined characterization by XPS, SEM, ellipsometry and cross-section TEM showed that insulating films of stoichiometric SiO2 and Si-rich Si3N4 were formed during IBO and IBN of Si at all energies used. The formation of Ge dielectric thin films by IBO and IBN was found to be strongly energy dependent and insulating layers could be grown only at the lower energies (E ≤ 200 eV). In contrast to pure Ge, insulating SiGe-oxide and SiGe-nitride were successfully formed on Si0.8Ge0.20.2 at all energies studied.

Dominant role of aortic baroreceptors in the cardiac baroreflex of the rat in situ

2008 ◽  
Vol 142 (1-2) ◽  
pp. 32-39 ◽  
Author(s):  
Anthony E. Pickering ◽  
Annabel E. Simms ◽  
Julian F.R. Paton
Keyword(s):  
Dominant Role ◽  
Aortic Baroreceptors

Photoemission Study of the Si, Ge Epitaxial Growth Process Using Surfactants

1992 ◽  
Vol 259 ◽  
Author(s):  
Xiaoyu Yang ◽  
Renyu Cao ◽  
Jeff Terry ◽  
Piero Pianetia
Keyword(s):  
Free Energy ◽  
Growth Process ◽  
Room Temperature ◽  
Energy Deposition ◽  
Low Energy ◽  
Heteroepitaxial Growth ◽  
Low Energy Electron Diffraction ◽  
Low Energy Electron ◽  
Photoemission Study

ABSTRACTHeteroepitaxial growth of Ge on Si(100) and Si on Ge(100) surfaces with Sb as a surfactant has been investigated by in situ high resolution photoemission and low energy electron diffraction (LEED). Our results show that an ordered monolayer of Sb atoms saturate the surface dangling bonds and consequently lower the surface free energy. Deposition of Ge or Si on the Sb/Si(100) or Sb/Ge(100) surfaces either at room temperature, followed by mild annealing or deposition at elevated temperature, result in an epitaxial layer of Ge or Si on the substrate, respectively. We provide clear experimental evidence that the deposited Ge or Si atoms changes position with the surface Sb atoms in this process. Ge or Si atoms occupy the epitaxial sites previously occupied by the Sb atoms. The Sb atoms in turn segregate to the surface and form a new ordered layer. The Bi-assisted growth process is also discussed.

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