Atomic Structure of the Epitaxial Al/Si Interface

1984 ◽  
Vol 37 ◽  
Author(s):  
F. K. LeGoues ◽  
W. Krakow ◽  
P. S. Ho
Keyword(s):  
Electron Microscopy ◽  
Atomic Structure ◽  
Amorphous Layer ◽  
The Other ◽  
Atomic Model ◽  
Native Oxide ◽  
Cross Sectional ◽  
Disordered Layer

AbstractAl was deposited on Si(l l l) and observed by cross-sectional electron microscopy, both in the annealed and as deposited states. It is shown that Al is strongly textured when deposited on Si(111), with Al(111)//Si(111) and AI<110>//Si<110> or AI(100)//Si(111) and AI<I10>//Si<110>. Annealed samples are completely epitaxial with A1(111)//Si(111) and A1<110>//Si<110>. Lattices imaging of the interfaces shows an amorphous layer (native Si oxide) between Al and Si, in the as-deposited case. The two lattices are in contact only at pinholes in the native oxide and fringes on both sides of the interface are seen to be continuous through the interface only at those points. Annealed samples do not show any amorphous or disordered layer at the interface: The two lattices are completely in contact, with lattice fringes extending from one side of the interface to the other. An atomic model of the annealed interface, based on energy considerations and consistent with TEM observations, is proposed.

Role of Implant Energy on Defect Structures for Phosphorus Implanted Silicon

1986 ◽  
Vol 71 ◽  
Author(s):  
S. Prussin ◽  
Kevin S. Jones
Keyword(s):  
Electron Microscopy ◽  
Transmission Electron Microscopy ◽  
Energy Range ◽  
Amorphous Layer ◽  
The Other ◽  
Defect Structures ◽  
Cross Sectional ◽  
Transmission Electron ◽  
Good Contact

AbstractA series of 18 wafers were implanted with phosphorus ions covering an energy range of 25 to 180 keV at a dose of 1 × 1015 cm−2 using a Waycool end station which provides good contact between the wafers and a thermal sink. Half the wafers had {100} surfaces and the other half {111} surfaces. The morphology of the as-implanted surface, defined by the thickness of the amorphous layer and whether that layer was submerged or lay at the surface, was affected by implant energy and surface orientation. After a 550°C regrowth and an activation anneal of 30 minutes at 900°C, the defect structures were evaluated by plan and cross-sectional transmission electron microscopy. A dear correlation was found between the implant morphology, the wafer orientation, and the defect structures.

Role of EM in interface science and engineering

1992 ◽  
Vol 50 (1) ◽  
pp. 208-209
Author(s):  
Gareth Thomas
Keyword(s):  
Electron Microscopy ◽  
Phase Contrast ◽  
Displacement Vector ◽  
The Other ◽  
Science And Engineering ◽  
Cross Sectional ◽  
Important Group ◽  
The World ◽  
Interface Science

The world of materials is a world of interfaces. Indeed many technologically significant materials have properties both physical and mechanical which are determined by the structure, composition, and bonding of the interfaces within these materials. Thus, electron microscopy and microanalysis, with its high resolution and specificity of information, is one of the key methods needed for characterization. Imaging can be done by amplitude contrast but is limited by the factor g • R (where R is a displacement vector), or resolution in phase contrast, and in today's modern instruments atomic arrangements can be imaged directly, both in plan and cross-sectional views. Beautiful examples are now being published. However so far, few developments to utilize this information for materials design have been forthcoming. On the other hand, interface or intergranular phases are very important in many metallurgical and ceramic systems. In fact many materials are composites of one kind or another and composites involving intergranular phases are an important group of such materials.

A Novel Process to Form Epitaxial Si Structures With Buried Silicide

1991 ◽  
Vol 235 ◽  
Author(s):  
YU. N. Erokhin ◽  
R. Grotzschel ◽  
S. R. Oktyabrski ◽  
S. Roorda ◽  
W. Sinke ◽  
...  
Keyword(s):  
Electron Microscopy ◽  
Thermal Annealing ◽  
Crystalline Silicon ◽  
Rutherford Backscattering Spectrometry ◽  
Amorphous Layer ◽  
Cross Sectional ◽  
X Ray ◽  
Metal Atoms ◽  
Transmission Electron ◽  
High Metal

ABSTRACTThe interaction during low temperature thermal annealing of metal atoms from a Ni film evaporated on top of Si structures with a buried amorphous layer formed by ion implantation has been investigated. Rutherford Backscattering Spectrometry (RBS)/channeling, cross-sectional transmission electron microscopy (XTEM) and X-ray microanalysis were used to determine structures and compositions. It is shown that the combination of such silicon properties as the increased rate of silicidation reaction for amorphous silicon with respect to the crystalline one in combination with high metal atom diffusivity leads to formation of buried epitaxial Ni silicide islands at the interface between the amorphous and the top crystalline silicon layers. During thermal annealing at temperatures as low as 350° C, these islands move through the a-Si layer leaving behind epitaxially recrystallized Si.

Implant Damage in AlGaAs Based Superlattices and Alloys at 77K

1989 ◽  
Vol 147 ◽  
Author(s):  
E. A. Dobisz ◽  
H. Dietrich ◽  
A. W. McCormick ◽  
J. P. Harbison
Keyword(s):  
Electron Microscopy ◽  
Transmission Electron Microscopy ◽  
Layer Thickness ◽  
Room Temperature ◽  
Amorphous Layer ◽  
Current Work ◽  
Cross Sectional ◽  
Bulk Gaas ◽  
Transmission Electron ◽  
Extensive Damage

AbstractPreviously, it was shown that superlattices implanted with Si at 77K, exhibited more extensive damage and uniform compositional mixing upon subsequent annealing than samples implanted at room temperature.[l,2] The current work focuses on the damage in samples implanted with Si at 77K. The study shows that for a given dose, the amount of damage depends upon the layer thickness and the composition. Specimens of bulk GaAs, Al 3Ga. 7As, 7.5 nm GaAs -10 nm Al. 3Ga. 7As superlattice (SL1), 5.5 nm GaAs −3.5 nm AlAs superlattice (SL2), and 8.0 nm GaAs −8.0 nm AlAs superlat-tice (SL3) were implanted at 77K with 100 KeV Si, with doses ranging from 3 × 1013 cm−2 to 1 × 1015 cm−2. The samples were examined by ion channelling and cross sectional transmission electron microscopy (TEM). At 77K and a dose of 1 × 1014 cm−2, the GaAs and SLi showed an amorphous layer, while no damage peak was observed in SL2. The 77K amorphization thresholds of the Al 3Ga. 7As alloy, SL2, and SL3 were 2.5 × 1014 cm−2, 4 × 1014 cm−2, and 1 × 1015 cm−2 respectively. The sharpness of the amorphization threshold varied with the material.

scholarly journals The Ultrastructure of Schmidt-Lanterman Clefts and Related Shearing Defects of the Myelin Sheath

1958 ◽  
Vol 4 (1) ◽  
pp. 39-46 ◽  
Author(s):  
J. David Robertson
Keyword(s):  
Electron Microscopy ◽  
Endoplasmic Reticulum ◽  
Schwann Cell ◽  
Outer Layer ◽  
Dynamic Process ◽  
Myelin Sheath ◽  
The Other ◽  
Cross Sectional ◽  
Thin Sections ◽  
Sciatic Nerves

Schmidt-Lanterman clefts in frog sciatic nerves have been studied in thin sections by electron microscopy utilizing permanganate fixation and araldite embedding. It is shown that they are shearing defects in myelin in which the lamellae are separated widely at the major dense lines. Each lamella consisting of two apposed Schwann cell unit membranes ∼ 75 A across traverses the cleft intact. The unit membranes composing each lamella sometimes are slightly (∼ 50 to 100 A) separated in the clefts. The layers between the lamellae contain membranous structures which may be components of the endoplasmic reticulum. These layers are continuous with the outer layer of Schwann cytoplasm and the thin and inconstant cytoplasmic layer next to the axon (Mauthner's sheath). Each of these layers in perfect clefts constitutes a long helical pathway through the myelin from the axon. One of these is connected with Schwann cytoplasm and the other directly with the outside. A type of cross-sectional shearing defect, not hitherto recognized, is described and shown to be a kind of Schmidt-Lanterman cleft. Incomplete clefts are seen and interpreted as representing stages in a dynamic process whereby the myelin lamellae may be constantly separating and coming together again in life.

Oxidation and crystallization of an amorphous Zr60Al15Ni25 alloy

1996 ◽  
Vol 11 (11) ◽  
pp. 2738-2743 ◽  
Author(s):  
X. Sun ◽  
S. Schneider ◽  
U. Geyer ◽  
W. L. Johnson ◽  
M-A. Nicolet
Keyword(s):  
Electron Microscopy ◽  
Transmission Electron Microscopy ◽  
Amorphous Alloy ◽  
Oxidation Process ◽  
Amorphous Layer ◽  
Intermetallic Phases ◽  
Annealing Duration ◽  
Oxide Layer Thickness ◽  
Cross Sectional ◽  
Transmission Electron

The amorphous ternary metallic alloy Zr60Al15Ni25 was oxidized in dry oxygen in the temperature range 310 °C to 410 °C. Rutherford backscattering (RBS) and cross-sectional transmission electron microscopy (TEM) studies suggest that during this treatment an amorphous layer of zirconium-aluminum-oxide is formed at the surface. Nickel was depleted in the oxide and enriched in the amorphous alloy near the interface. The oxide layer thickness grows parabolically with annealing duration, with a transport constant of 2.8 × 10−5 m2/s × exp(−1.7 eV/kT). The oxidation rate may be controlled by the diffusion of Ni in the amorphous alloy. At later stages of the oxidation process, precipitates of nanocrystalline ZrO2 appear in the oxide near the interface. Finally, two intermetallic phases nucleate and grow simultaneously in the alloy, one at the interface and one within the alloy. An explanation involving preferential oxidation is proposed.

scholarly journals Extreme Sub-Wavelength Structure Formation from Mid-IR Femtosecond Laser Interaction with Silicon

Nanomaterials ◽  
2021 ◽  
Vol 11 (5) ◽  
pp. 1192
Author(s):  
Kevin Werner ◽  
Enam Chowdhury
Keyword(s):  
Electron Microscopy ◽  
Femtosecond Laser ◽  
Structure Formation ◽  
Single Crystal Silicon ◽  
Pulse Number ◽  
Native Oxide ◽  
New Paradigm ◽  
Crystal Silicon ◽  
Cross Sectional ◽  
Sub Wavelength

Mid-infrared (MIR) wavelengths (2–10 μm) open up a new paradigm for femtosecond laser–solid interactions. On a fundamental level, compared to the ubiquitous near-IR (NIR) or visible (VIS) laser interactions, MIR photon energies render semiconductors to behave like high bandgap materials, while driving conduction band electrons harder due to the λ2 scaling of the ponderomotive energy. From an applications perspective, many VIS/NIR opaque materials are transparent for MIR. This allows sub-surface modifications for waveguide writing while simultaneously extending interactions to higher order processes. Here, we present the formation of an extreme sub-wavelength structure formation (∼λ/100) on a single crystal silicon surface by a 3600 nm MIR femtosecond laser with a pulse duration of 200 fs. The 50–100 nm linear structures were aligned parallel to the laser polarization direction with a quasi-periodicity of 700 nm. The dependence of the structure on the native oxide, laser pulse number, and polarization were studied. The properties of the structures were studied using scanning electron microscopy (SEM), atomic force microscopy (AFM), cross-sectional transmission electron-microscopy (CS-TEM), electron diffraction (ED), and energy-dispersive X-ray spectroscopy (EDX). As traditional models for the formation of laser induced periodic surface structure do not explain this structure formation, new theoretical efforts are needed.

Kinetics of Metallic Glass Formation by Solid State Reactions

1985 ◽  
Vol 57 ◽  
Author(s):  
K. Samwer ◽  
H Schröder ◽  
M. Moske
Keyword(s):  
Electron Microscopy ◽  
Solid State ◽  
Metallic Glass ◽  
Glass Formation ◽  
Amorphous Layer ◽  
Solid State Reactions ◽  
Diffusion Couples ◽  
Cross Sectional ◽  
Transmission Electron ◽  
Kinetics Of

AbstractMetallic glass formation by solid state reactions has been observed in multilayer Zr-Co diffusion couples. The kinetics of the reaction are limited by the diffusion of the Co-atoms in the growing amorphous layer, at least for longer times, as shown by cross-sectional transmission electron microscopy and resistance measurements. The latter one provides the interdiffusion constant and the activation energy of about 1.1 eV. Deposition of the crystalline layers at 77 K results in an enhanced amorphization process in the first stage of the reaction and gives preliminary answers about the nucleation of the amorphous phase.

Kinetic and Thermodynamic Aspects of Phase Evolution in Ti/a-Si Multilayer Films

1990 ◽  
Vol 187 ◽  
Author(s):  
E. Ma ◽  
L.A. Clevenger ◽  
C.V. Thompson ◽  
K.N. Tu
Keyword(s):  
Electron Microscopy ◽  
Metastable Phase ◽  
Phase Evolution ◽  
Amorphous Layer ◽  
Multilayer Films ◽  
Solid State Reactions ◽  
Scanning Calorimetry ◽  
Cross Sectional ◽  
Subsequent Formation ◽  
Transmission Electron

AbstractThe growth of an amorphous Ti-Si phase and subsequent formation of crystalline silicides during solid-state reactions in Ti/a-Si multilayer films have been studied using power-compensated differential scanning calorimetry, cross-sectional transmission electron microscopy, and thin-film x-ray diffraction. By analyzing calorimetric data we have determined the activation energies for the formation of the various silicides (amorphous Ti-silicide, TiSi, C49-TiSi2, Ti5Si3) as well as their heats of formation. An amorphous silicide is the first phase to form during heating and we have measured the composition profile of this amorphous layer using scanning transimission electron microscopy. Metastable phase equilibria in the Ti-Si system are discussed in light of the thermodynamic and compositional information obtained in our experiments.

scholarly journals Atomic structure of the 26S proteasome lid reveals the mechanism of deubiquitinase inhibition

eLife ◽  
2016 ◽  
Vol 5 ◽  
Author(s):  
Corey M Dambacher ◽  
Evan J Worden ◽  
Mark A Herzik ◽  
Andreas Martin ◽  
Gabriel C Lander
Keyword(s):  
Electron Microscopy ◽  
Atomic Structure ◽  
26S Proteasome ◽  
Atomic Model ◽  
Cellular Proteins ◽  
Cryo Electron Microscopy ◽  
Substrate Degradation ◽  
Conformational Rearrangements ◽  
Substrate Processing ◽  
Insight Into

The 26S proteasome is responsible for the selective, ATP-dependent degradation of polyubiquitinated cellular proteins. Removal of ubiquitin chains from targeted substrates at the proteasome is a prerequisite for substrate processing and is accomplished by Rpn11, a deubiquitinase within the ‘lid’ sub-complex. Prior to the lid’s incorporation into the proteasome, Rpn11 deubiquitinase activity is inhibited to prevent unwarranted deubiquitination of polyubiquitinated proteins. Here we present the atomic model of the isolated lid sub-complex, as determined by cryo-electron microscopy at 3.5 Å resolution, revealing how Rpn11 is inhibited through its interaction with a neighboring lid subunit, Rpn5. Through mutagenesis of specific residues, we describe the network of interactions that are required to stabilize this inhibited state. These results provide significant insight into the intricate mechanisms of proteasome assembly, outlining the substantial conformational rearrangements that occur during incorporation of the lid into the 26S holoenzyme, which ultimately activates the deubiquitinase for substrate degradation.

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