High-Resolution Core Level Studies of Interdiffusion and Reaction at Metal-Semiconductor Interfaces

1986 ◽  
Vol 77 ◽  
Author(s):  
M. Del Giudice ◽  
J. J. Joyce ◽  
F. Boscherini ◽  
C. Capasso ◽  
J. H. Weaver
Keyword(s):  
High Resolution ◽  
Binding Energy ◽  
Refractory Metal ◽  
Room Temperature ◽  
Chemical Shifts ◽  
Microscopic Investigation ◽  
Core Level ◽  
Semiconductor Surface ◽  
Intensity Attenuation ◽  
Semiconductor Interfaces

ABSTRACTWe present a detailed microscopic investigation of interactions and reactions occurring at refractory-metal silicon interfaces at room temperature. High resolution core level photoemission results for Ti coverages in the range 0.2–16 monolayers on cleaved Si(111)2×1 show that three new distinct Si environments are created by semiconductor surface disruption. In agreement with heats of formation or electronegativity differences, all the chemical shifts are at lower binding energy. Each of them represents a different metal-Si coordination or configuration. Analogous results for Sc overlayers indicate that at least two reacted species are present. For both Ti and Sc, the reaction is started at submonolayer coverages. Analysis of the Si 2p intensity attenuation curves shows an evolution characterized by the sequential growth of the different species. Indeed, each species grows, reaches saturation, and is then attenuated. This is associated with the competition between diffusion and reaction at the interface.

Synchrotron Photoemission Studies of Surfaces and Overlayers

1988 ◽  
Vol 143 ◽  
Author(s):  
T.-C. Chiang
Keyword(s):  
High Resolution ◽  
Binding Energy ◽  
Electronic Properties ◽  
Atomic Structure ◽  
Chemical Shifts ◽  
Quantitative Description ◽  
Photoemission Spectroscopy ◽  
Electronegativity Difference ◽  
Model Structures ◽  
Reference Samples

AbstractHigh-resolution core-level photoemission spectroscopy allows the distinction of atoms in different layers and in inequivalent sites by their binding energy shifts. By comparison with model structures and reference samples, the number of atoms in each distinct chemical configuration can be determined. The chemical shifts induced by adsorption can be correlated with the electronegativity difference between the substrate and the adsorbate atoms. These observations provide a quantitative description of the interaction and reaction between adsorbates and surfaces, and important information about the atomic structure and the electronic properties can be deduced. Results from several representative systems including the adsorption of In, Ag, and Sn on Si(100) will be discussed.

An ESCA Investigation of some Halogeno(methyl)-Silane and -Germane Series

1975 ◽  
Vol 53 (23) ◽  
pp. 3602-3612 ◽  
Author(s):  
John E. Drake ◽  
Chris Riddle ◽  
L. Coatsworth
Keyword(s):  
Binding Energy ◽  
Chemical Shifts ◽  
Binding Energies ◽  
Core Level ◽  
Atomic Charges ◽  
Electronegativity Equalization

Core-level binding energies of all atoms are reported for two series of compounds; MenMCl4−n and Me3MX (n = 0 → 4, M = Si or Ge, X = F, Cl, Br, I and (for M = Ge) CN, N3, and NCS ). Binding energy shifts are discussed using a 'whole-molecule' approach and are correlated with estimated atomic charges derived from an electronegativity-equalization procedure. Carbon 1s binding energies are also correlated to 13C n.m.r. chemical shifts.

HIGH-RESOLUTION Si2p CORE-LEVEL STUDY OF THE K/Si(111)-(3 × 1) SURFACE

2002 ◽  
Vol 09 (02) ◽  
pp. 1235-1239 ◽  
Author(s):  
KAZUYUKI SAKAMOTO ◽  
H. M. ZHANG ◽  
ROGER I. G. UHRBERG
Keyword(s):  
High Resolution ◽  
Binding Energy ◽  
Photoelectron Spectroscopy ◽  
Binding Energies ◽  
Core Level ◽  
Three Components

The structure of the K/Si (111)-(3 × 1) surface was studied by high-resolution core-level photoelectron spectroscopy. Five surface components were observed in the Si 2p core-level spectra. Compared to the bulk component, three components are shifted to lower and two to higher binding energies. The two components with the lowest binding energies are assigned to the top-layer Si atoms bonded to the K atoms with different configurations. The component with highest binding energy has a contribution from the π-bonded Si atoms of the top layer. The two other components originate from the Si atoms of the second and third layers.

High-Resolution Core Level Study of the Co/Si(111) Interface

1986 ◽  
Vol 83 ◽  
Author(s):  
F. Boscherini ◽  
J. J. Joyce ◽  
M. W. Ruckman ◽  
J. H. Weaver
Keyword(s):  
High Temperature ◽  
High Resolution ◽  
Schottky Barrier ◽  
Barrier Height ◽  
Room Temperature ◽  
Schottky Barrier Height ◽  
Core Level ◽  
Reaction Products ◽  
Semiconductor Structures ◽  
Epitaxial Interface

There has recently been considerable interest in the reaction between Co and a clean Si surface. This interest stems from the epitaxy of CoSi2 and NiSi2 on Si and its potential for the construction of reliable and stable metal-semiconductor structures. In fact, the fabrication of a Si/CoSi2/Si transistor has been recently reported.[l] On a more fundamental side, it has been possible to address the problem of the relation between Schottky barrier height and structure at the NiSi2/Ni interface, which exhibits both a rotated (B-type) and unrotated (A-type) geometry.[2] For CoSi2/Si only the 180° rotated, B-type disilicide is formed. By studying the room temperature interface, we have attempted to describe the nature and physical extent of reaction products; such knowledge is important to understand the formation of interface silicides which ultimately control the nature of the high temperature epitaxial interface.

HIGH RESOLUTION CORE LEVEL SPECTROSCOPY AT THE Cu/Ru(0001) INTERFACE

2002 ◽  
Vol 09 (02) ◽  
pp. 723-727 ◽  
Author(s):  
T. H. ANDERSEN ◽  
L. BECH ◽  
J. ONSGAARD ◽  
S. V. HOFFMANN ◽  
Z. LI
Keyword(s):  
High Resolution ◽  
Synchrotron Radiation ◽  
Binding Energy ◽  
Energy Shift ◽  
Core Level ◽  
Photoemission Spectroscopy ◽  
Copper Adsorption ◽  
X Ray ◽  
Level Shifts ◽  
Binding Energy Shift

Copper adsorption on Ru(0001) has been studied by synchrotron radiation. The clean Ru 3d 5/2 spectra were found to consist of two components with a binding energy shift of 400 meV. The component with the lower binding energy represents the first layer of ruthenium atoms. Adsorption of copper gives rise to core level shifts of the Ru 3d 5/2 components, which were studied as a function of Cu coverage. Experiments were carried out with copper coverages varying from the submonolayer range up to two monolayers of copper. The binding energy of the Cu 2p 3/2 level was measured by X-ray photoemission spectroscopy.

A Liquid Nitrogen Cooled Stage for STEM

1974 ◽  
Vol 32 ◽  
pp. 444-445
Author(s):  
Louis T. Germinario
Keyword(s):  
Electron Microscope ◽  
High Resolution ◽  
Liquid Nitrogen ◽  
Room Temperature ◽  
Objective Lens ◽  
Thermal Drift ◽  
Specimen Holder ◽  
Resolution Capability ◽  
Focal Position

A liquid nitrogen stage has been developed for the JEOL JEM-100B electron microscope equipped with a scanning attachment. The design is a modification of the standard JEM-100B SEM specimen holder with specimen cooling to any temperatures In the range ~ 55°K to room temperature. Since the specimen plane is maintained at the ‘high resolution’ focal position of the objective lens and ‘bumping’ and thermal drift la minimized by supercooling the liquid nitrogen, the high resolution capability of the microscope is maintained (Fig.4).

High-Resolution Scanning Electron Microscopy of Biological Specimens

1988 ◽  
Vol 46 ◽  
pp. 186-187
Author(s):  
M. Müller ◽  
R. Hermann
Keyword(s):  
High Resolution ◽  
Freeze Drying ◽  
Room Temperature ◽  
Structural Information ◽  
Freeze Substitution ◽  
Critical Point Drying ◽  
Sem Study ◽  
Major Factors ◽  
Structural Preservation ◽  
Preparation Techniques

Three major factors must be concomitantly assessed in order to extract relevant structural information from the surface of biological material at high resolution (2-3nm).Procedures based on chemical fixation and dehydration in graded solvent series seem inappropriate when aiming for TEM-like resolution. Cells inevitably shrink up to 30-70% of their initial volume during gehydration; important surface components e.g. glycoproteins may be lost. These problems may be circumvented by preparation techniques based on cryofixation. Freezedrying and freeze-substitution followed by critical point drying yields improved structural preservation in TEM. An appropriate preservation of dimensional integrity may be achieved by freeze-drying at - 85° C. The sample shrinks and may partially collapse as it is warmed to room temperature for subsequent SEM study. Observations at low temperatures are therefore a necessary prerequisite for high fidelity SEM. Compromises however have been unavoidable up until now. Aldehyde prefixation is frequently needed prior to freeze drying, rendering the sample resistant to treatment with distilled water.

High-resolution z-contrast imaging of semiconductor interfaces

1989 ◽  
Vol 47 ◽  
pp. 468-469
Author(s):  
S. J. Pennycook
Keyword(s):  
High Resolution ◽  
Phase Contrast ◽  
Contrast Imaging ◽  
Compositional Modulation ◽  
Semiconductor Interfaces ◽  
Complex Figure ◽  
Thin Region ◽  
Stem Image ◽  
Annular Detector ◽  
Z Contrast

Using a high-angle annular detector on a high-resolution STEM it is possible to form incoherent images of a crystal lattice characterized by strong atomic number or Z contrast. Figure 1 shows an epitaxial Ge film on Si(100) grown by oxidation of Ge-implanted Si. The image was obtained using a VG Microscopes' HB501 STEM equipped with an ultrahigh resolution polepiece (Cs ∽1.2 mm, demonstrated probe FWHM intensity ∽0.22 nm). In both crystals the lattice is resolved but that of Ge shows much brighter allowing the interface to be located exactly and interface steps to be resolved (arrowed). The interface was indistinguishable in the phase-contrast STEM image from the same region, and even at higher resolution the location of the interface is complex. Figure 2 shows a thin region of an MBE-grown ultrathin super-lattice (Si8Ge2)100. The expected compositional modulation would show as one bright row of dots from the 2 Ge monolayers separated by 4 rows of lighter Si columns. The image shows clearly that strain-induced interdiffusion has occurred on the monolayer scale.

The High Resolution NMR Spectra of Pesticides. II. The DDT-Type Compounds

1969 ◽  
Vol 52 (5) ◽  
pp. 1074-1092 ◽  
Author(s):  
L H Keith ◽  
A L Alford ◽  
A W Garrison
Keyword(s):  
Nuclear Magnetic Resonance ◽  
High Resolution ◽  
Nmr Spectra ◽  
Chemical Shifts ◽  
Coupling Constants ◽  
Aromatic Rings ◽  
Nuclear Magnetic Resonance Spectra ◽  
High Resolution Nmr ◽  
Related Compounds ◽  
Deshielding Effect

Abstract The high resolution nuclear magnetic resonance spectra of the DDT class of pesticides and related compounds are discussed, including a study of the resonances of the aromatic protons as they are affected by various substiluents. The CCl3 moiety on the α-carbon strongly deshields the ortho protons on the aromatic rings, and this deshielding effect is greatly enhanced by substitution of a chlorine ortho rather than para on the aromatic ring. These deshielding effects are explained by a consideration of the electronegativity of the substituents and the stereochemistry of the molecule. The chemical shifts and coupling constants are tabulated.

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