Growth of Thin Nickel Silicide Layers on Clean B-Doped Si(111) Surfaces at Room Temperature

1989 ◽  
Vol 160 ◽  
Author(s):  
L. Luo ◽  
G. A. Smith ◽  
W. M. Gibson
Keyword(s):  
Monte Carlo ◽  
Computer Simulations ◽  
Room Temperature ◽  
High Energy ◽  
Nickel Silicide ◽  
Growth Stages ◽  
Initial Growth ◽  
Fourth Layer ◽  
Ion Channeling ◽  
Thin Nickel

AbstractThe initial growth stages of Ni on clean B-doped Si(111) were studied at room temperature using high energy Ion channeling and Monte Carlo computer simulations of the Ni/Si interface. The results suggest that the first monolayer of Ni atoms diffuse to reaction sites in the fourth layer of the Si(111) substrate where nickel suicide growth begins. Further Ni deposition (up to ~ 3 ML) leads to the growth of NiSi2 which is thought to be a diffusion barrier that terminates further formation of NiSi2 at room temperature.

Silver Nanocrystals at Cavities Created by High Energy Helium Implantation in Bulk Silicon

2007 ◽  
Vol 994 ◽  
Author(s):  
Rachid El Bouayadi ◽  
Gabrielle Regula ◽  
Maryse Lancin ◽  
Eduardo Larios ◽  
Bernard Pichaud ◽  
...  
Keyword(s):  
Room Temperature ◽  
High Energy ◽  
Nickel Silicide ◽  
Bulk Silicon ◽  
Shape Characteristic ◽  
Transmission Electron ◽  
Helium Implantation ◽  
Ag Deposition ◽  
First Time ◽  
Good Agreement

AbstractHigh resolution transmission electron microscopy observations show for the first time the presence of two orientations of pure silver precipitates in nanocavities induced in bulk silicon by implantation at 1.6 MeV with a dose of 5×1016 He+ cm−2 and a two hour annealing at 1050°C. These precipitates were called A and B to refer to the two well-known nickel silicide (NiSi2) precipitates or Ag films on a {111} silicon surface. Thus, the A precipitate corresponds to a growth of silver nanocrystal on {111} cavity walls in epitaxy with the Si matrix with an orientation relationship Ag(-111)[211]||Si(-111)[211]. The B precipitate develops on a {111} plane parallel to a {111} cavity wall as well, but in a twin orientation with respect to the Si matrix defined by Ag(-111)[211]||Si(-111)[-2-1-1]. The Ag nanocrystals have a size ranging from a few nm to 50 nm. Most of them have the faceted-shape characteristic of “clean” cavities. They are either A precipitates or they contain alternatively A and B bands in good agreement with both the low stacking fault energy of silver and the two types of nanocrystal orientations obtained by Ag deposition on (111) Si substrate at room temperature. Some Ag precipitates were also found at dislocations located at the He+ projection range, but these trapping sites were found thermally unstable as compared to the cavity ones. Indeed, during a second identical annealing, the precipitates grow in cavities whereas they fade at dislocations.

ALLOY FORMATION OF ULTRATHIN Ni FILMS ON Al(111) SURFACE AT ROOM TEMPERATURE

1999 ◽  
Vol 06 (05) ◽  
pp. 781-786 ◽  
Author(s):  
Y. W. KIM ◽  
G. A. WHITE ◽  
R. REIBEL ◽  
R. J. SMITH
Keyword(s):  
Photoelectron Spectroscopy ◽  
Room Temperature ◽  
High Energy ◽  
Alloy Formation ◽  
Ion Scattering ◽  
Xps Spectra ◽  
Ion Channeling ◽  
Low Energy Ion Scattering ◽  
Nial Phase ◽  
Nial Alloy

The growth characteristics of ultrathin Ni films deposited on Al(111) surfaces at room temperature have been studied using high energy ion scattering/channeling (HEIS), X-ray photoelectron spectroscopy (XPS) and low energy ion scattering (LEIS). Ion channeling results show that Ni atoms deposited on the Al(111) surface react with Al substrate atoms to form two different Ni–Al alloys between 0 and 5.5 ML of Ni coverage. Alloy phases of Ni 2 Al 3 up to 1.5 ML and NiAl up to 5.5 ML were determined by XPS peak analysis. At higher Ni coverage, LEIS and XPS spectra suggest that islands of Ni metal were formed on the surface. Diffusion of Ni into the Al substrate or segregation of Al to the surface was observed during the alloy formation. The Ni 2 Al 3 phase was apparently transformed into the NiAl phase by the additional Ni deposition, and the islands of Ni metal formed on the Al-rich surface of the NiAl alloy.

Structure and Chemistry of Ti Overlayers on α-Αl2O3(0001)

1997 ◽  
Vol 472 ◽  
Author(s):  
S. Bernath ◽  
T. Wagner ◽  
S. Hofmann ◽  
M. Rühle
Keyword(s):  
Thin Films ◽  
Electron Diffraction ◽  
Room Temperature ◽  
Growth Stage ◽  
Molecular Beam ◽  
High Energy ◽  
Initial Growth ◽  
High Energy Electron ◽  
Incoherent Interface ◽  
Temperature Deposition

ABSTRACTTi thin films were grown by molecular-beam epitaxy (MBE) on α-Al2O3(0001) substrates. During room temperature deposition, in the very initial growth stage, AES investigations revealed a chemical reaction between the Ti and the α-Al2O3 substrate. An analysis of the AES data based on simple assumptions showed that ∼ 2 monolayers of Ti are oxidized. However, HRTEM analysis indicated an atomically smooth, incoherent interface, without a reaction layer. Reflection high-energy electron diffraction (RHEED) analysis revealed an epitaxial orientation relationship (0001)<2110> Ti ∥ (0001)<1010>Al2O3 between Ti and α-Al2O3(0001).

The Growth of GaAs on Si by Molecular Beam Epitaxy

1986 ◽  
Vol 67 ◽  
Author(s):  
S. M. Koch ◽  
S. J. Rosner ◽  
Darrell Schlom ◽  
J. S. Harris
Keyword(s):  
Growth Temperature ◽  
Molecular Beam ◽  
High Energy ◽  
Buffer Layers ◽  
Initial Growth ◽  
Photoluminescence Intensity ◽  
Ion Channeling ◽  
Gaas On Si

ABSTRACTSuccessful growth of GaAs on Si has recently been demonstrated. This work is directed toward an understanding of the processes occurring during the growth and their effects on the quality of the GaAs epilayers. Reflection High Energy Electron Diffraction monitoring of the growth in situ shows that the islands that are initially formed coalesce into an epilayer with a 2×4 surface reconstruction. Ion channeling indicates that the crystallinity of the entire epilayer improves with coverage. Substantial reordering of the material occurs when buffer layers grown at low temperatures are annealed at 575°C before and during further growth at this temperature. Comparison of 300 nm layers differing in the growth temperature of the first 100 nm shows no variation in the crystallinity as determined by ion channeling. Surface morphology degrades, however, and 77K photoluminescence intensity rises with the initial growth temperature. The optical and structural properties of 2μm thick films are also discussed.

Long Range Order in Ultra-Thin SiO2 Grown on Ordered Si(100)

1999 ◽  
Vol 567 ◽  
Author(s):  
Q.B. Hurst ◽  
N. Herbots ◽  
J.M. Shaw ◽  
M.M. Floyd ◽  
D.J. Smith ◽  
...  
Keyword(s):  
Room Temperature ◽  
Ion Beam ◽  
Ambient Air ◽  
High Energy ◽  
Thermally Grown Oxide ◽  
Chemical Cleaning ◽  
Ion Channeling ◽  
Beam Analysis ◽  
Charge Analysis ◽  
Wet Chemical

ABSTRACTIn this paper, we investigate the correlation of electrical properties and structure of 1-4 nm thick SiO2 grown on H-passivated Si(100) for ultra-thin gate applications. Ordered (1×1) Si(100) stable in ambient air is obtained at room temperature by wet chemical cleaning. Ion Beam Analysis using a combination of ion channeling and 16O(α,α)16O nuclear resonance yields Si areal densities lower than that of a bulk-terminated Si crystal as calculated by Monte-Carlo simulations. This result indicates shadowing of Si substrate atoms by Si atoms in the thermally grown oxide. Detection of order by ion channeling is supported by Reflection High Energy Electron Diffraction (RHEED). C-V and I-V measurements are generally inconclusive for ultra-thin (1-2 nm) oxides because of leakage and breakdown. Surface charge analysis enables a comparison between ordered oxides and conventional oxides. The results are promising.

scholarly journals Exploiting the Nucleophilicity of the Nitrogen Atom of Imidazoles: One-Pot Three-Component Synthesis of Imidazo-Pyrazines

Molecules ◽  
2019 ◽  
Vol 24 (10) ◽  
pp. 1959
Author(s):  
Ubaldina Galli ◽  
Rejdia Hysenlika ◽  
Fiorella Meneghetti ◽  
Erika Del Grosso ◽  
Sveva Pelliccia ◽  
...  
Keyword(s):  
Nitrogen Atom ◽  
Multicomponent Reaction ◽  
Room Temperature ◽  
High Energy ◽  
One Pot ◽  
Ion Channeling

A novel one-pot multicomponent reaction to synthesize substituted imidazopyrazines is described. In brief, 1H-(imidazol-5-yl)-N-substituted methanamines react with aldehydes and isocyanides in methanol at room temperature to give imidazopyrazine derivatives in excellent yields. The imidazole nitrogen atom was able to intercept the nascent nitrilium ion, channeling the reaction toward to the sole formation of imidazopyrazines, suppressing the competitive formation of other possible side products deriving from the reaction with the high-energy nitrilium ion. The number of examples and the variability of the nature of isocyanides, aldehydes, and amine components herein employed, witness the robustness of this novel methodology.

Epitaxial growth manner and structure of superconducting oxide films

1990 ◽  
Vol 48 (4) ◽  
pp. 2-3
Author(s):  
Yoshichika Bando ◽  
Takahito Terashima ◽  
Kenji Iijima ◽  
Kazunuki Yamamoto ◽  
Kazuto Hirata ◽  
...  
Keyword(s):  
Ultrathin Films ◽  
Film Surface ◽  
High Energy ◽  
Epitaxial Films ◽  
Layer By Layer ◽  
Initial Growth ◽  
In Situ Growth ◽  
High Quality ◽  
Activated Reactive Evaporation

The high quality thin films of high-Tc superconducting oxide are necessary for elucidating the superconducting mechanism and for device application. The recent trend in the preparation of high-Tc films has been toward “in-situ” growth of the superconducting phase at relatively low temperatures. The purpose of “in-situ” growth is to attain surface smoothness suitable for fabricating film devices but also to obtain high quality film. We present the investigation on the initial growth manner of YBCO by in-situ reflective high energy electron diffraction (RHEED) technique and on the structural and superconducting properties of the resulting ultrathin films below 100Å. The epitaxial films have been grown on (100) plane of MgO and SrTiO, heated below 650°C by activated reactive evaporation. The in-situ RHEED observation and the intensity measurement was carried out during deposition of YBCO on the substrate at 650°C. The deposition rate was 0.8Å/s. Fig. 1 shows the RHEED patterns at every stage of deposition of YBCO on MgO(100). All the patterns exhibit the sharp streaks, indicating that the film surface is atomically smooth and the growth manner is layer-by-layer.

Monte Carlo Modelling of Secondary Electron Yield from Rough Surfaces

1990 ◽  
Vol 48 (1) ◽  
pp. 422-423
Author(s):  
John C. Russ
Keyword(s):  
Monte Carlo ◽  
Energy Loss ◽  
Secondary Electron ◽  
Secondary Electron Emission ◽  
Analytical Calculation ◽  
Mean Free Path ◽  
Single Scattering ◽  
High Energy ◽  
Secondary Electron Yield ◽  
Electron Yield

Monte-Carlo programs are well recognized for their ability to model electron beam interactions with samples, and to incorporate boundary conditions such as compositional or surface variations which are difficult to handle analytically. This success has been especially powerful for modelling X-ray emission and the backscattering of high energy electrons. Secondary electron emission has proven to be somewhat more difficult, since the diffusion of the generated secondaries to the surface is strongly geometry dependent, and requires analytical calculations as well as material parameters. Modelling of secondary electron yield within a Monte-Carlo framework has been done using multiple scattering programs, but is not readily adapted to the moderately complex geometries associated with samples such as microelectronic devices, etc.This paper reports results using a different approach in which simplifying assumptions are made to permit direct and easy estimation of the secondary electron signal from samples of arbitrary complexity. The single-scattering program which performs the basic Monte-Carlo simulation (and is also used for backscattered electron and EBIC simulation) allows multiple regions to be defined within the sample, each with boundaries formed by a polygon of any number of sides. Each region may be given any elemental composition in atomic percent. In addition to the regions comprising the primary structure of the sample, a series of thin regions are defined along the surface(s) in which the total energy loss of the primary electrons is summed. This energy loss is assumed to be proportional to the generated secondary electron signal which would be emitted from the sample. The only adjustable variable is the thickness of the region, which plays the same role as the mean free path of the secondary electrons in an analytical calculation. This is treated as an empirical factor, similar in many respects to the λ and ε parameters in the Joy model.

Neutron dose evaluation of Elekta Linac at two energies (10 & 18 MV) by MCNP code and comparison with experimental measurements

2014 ◽  
Vol 6 (1) ◽  
pp. 1006-1015
Author(s):  
Negin Shagholi ◽  
Hassan Ali ◽  
Mahdi Sadeghi ◽  
Arjang Shahvar ◽  
Hoda Darestani ◽  
...  
Keyword(s):  
Monte Carlo ◽  
Measurement Data ◽  
Calculated Data ◽  
High Energy ◽  
Neutron Dose ◽  
Dose Assessment ◽  
Photon Flux ◽  
Dose Equivalent ◽  
Monte Carlo Techniques ◽  
Neutron Dose Equivalent

Medical linear accelerators, besides the clinically high energy electron and photon beams, produce other secondary particles such as neutrons which escalate the delivered dose. In this study the neutron dose at 10 and 18MV Elekta linac was obtained by using TLD600 and TLD700 as well as Monte Carlo simulation. For neutron dose assessment in 2020 cm2 field, TLDs were calibrated at first. Gamma calibration was performed with 10 and 18 MV linac and neutron calibration was done with 241Am-Be neutron source. For simulation, MCNPX code was used then calculated neutron dose equivalent was compared with measurement data. Neutron dose equivalent at 18 MV was measured by using TLDs on the phantom surface and depths of 1, 2, 3.3, 4, 5 and 6 cm. Neutron dose at depths of less than 3.3cm was zero and maximized at the depth of 4 cm (44.39 mSvGy-1), whereas calculation resulted  in the maximum of 2.32 mSvGy-1 at the same depth. Neutron dose at 10 MV was measured by using TLDs on the phantom surface and depths of 1, 2, 2.5, 3.3, 4 and 5 cm. No photoneutron dose was observed at depths of less than 3.3cm and the maximum was at 4cm equal to 5.44mSvGy-1, however, the calculated data showed the maximum of 0.077mSvGy-1 at the same depth. The comparison between measured photo neutron dose and calculated data along the beam axis in different depths, shows that the measurement data were much more than the calculated data, so it seems that TLD600 and TLD700 pairs are not suitable dosimeters for neutron dosimetry in linac central axis due to high photon flux, whereas MCNPX Monte Carlo techniques still remain a valuable tool for photonuclear dose studies.

scholarly journals Research Progress toward Room Temperature Sodium Sulfur Batteries: A Review

Molecules ◽  
2021 ◽  
Vol 26 (6) ◽  
pp. 1535
Author(s):  
Yanjie Wang ◽  
Yingjie Zhang ◽  
Hongyu Cheng ◽  
Zhicong Ni ◽  
Ying Wang ◽  
...  
Keyword(s):  
Energy Storage ◽  
Room Temperature ◽  
High Energy ◽  
Safety Performance ◽  
High Energy Density ◽  
Research Progress ◽  
Storage Performance ◽  
Sulfur Battery ◽  
Sodium Sulfur Battery ◽  
Sodium Sulfur

Lithium metal batteries have achieved large-scale application, but still have limitations such as poor safety performance and high cost, and limited lithium resources limit the production of lithium batteries. The construction of these devices is also hampered by limited lithium supplies. Therefore, it is particularly important to find alternative metals for lithium replacement. Sodium has the properties of rich in content, low cost and ability to provide high voltage, which makes it an ideal substitute for lithium. Sulfur-based materials have attributes of high energy density, high theoretical specific capacity and are easily oxidized. They may be used as cathodes matched with sodium anodes to form a sodium-sulfur battery. Traditional sodium-sulfur batteries are used at a temperature of about 300 °C. In order to solve problems associated with flammability, explosiveness and energy loss caused by high-temperature use conditions, most research is now focused on the development of room temperature sodium-sulfur batteries. Regardless of safety performance or energy storage performance, room temperature sodium-sulfur batteries have great potential as next-generation secondary batteries. This article summarizes the working principle and existing problems for room temperature sodium-sulfur battery, and summarizes the methods necessary to solve key scientific problems to improve the comprehensive energy storage performance of sodium-sulfur battery from four aspects: cathode, anode, electrolyte and separator.

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