Initial Stage of Solid Phase Epitaxial Growth of GaAs Films on Vicinal Si (001) Substrate

1992 ◽  
Vol 263 ◽  
Author(s):  
W.K. Choo ◽  
I. Kim ◽  
J.Y. Lee ◽  
K.I. Cho ◽  
J.-L. Lee ◽  
...  
Keyword(s):  
Electron Microscopy ◽  
Critical Thickness ◽  
Solid Phase ◽  
Three Dimensional ◽  
Stacking Faults ◽  
Cross Sectional ◽  
Transmission Electron ◽  
Initial Stage ◽  
Gaas Films ◽  
Phase Proceeds

ABSTRACTThe initial stage of solid phase epitaxial (SPE) growth of GaAs films on the vicinal Si (001) substrate was investigated by high resolution transmission electron microscopy (H-RTEM). Cross-sectional [110] and [110] HRTEM images show that the SPE growth of crystalline GaAs islands from the amorphous phase proceeds via the formation of three-dimensional islands at the initial stage and islands' size and spacing are not critically dependent on the substrate tilt direction. The average vertical and lateral dimensions of islands were found to be 9 nm and 14 nm respectively, and the average island spacing was 10 nm. Moreover, many internal stacking faults (and/or microtwins) and a few dislocations have been already formed at this initial stage of growth. In addition, the critical thickness for misfit dislocation formation is found to depend upon the islands' lateral dimensions as well as the heights.

Solid Phase Epitaxial Regrowth of Implantation Amorphized Si0.7Ge0.3 Grown on (100) Silicon

1991 ◽  
Vol 235 ◽  
Author(s):  
C. Lee ◽  
K. S. Jones
Keyword(s):  
Defect Density ◽  
Solid Phase ◽  
Three Dimensional ◽  
Stacking Faults ◽  
Solid Phase Epitaxy ◽  
Cross Sectional ◽  
Strained Layers ◽  
Epitaxial Regrowth ◽  
Transmission Electron ◽  
Interfacial Strain

ABSTRACTThe solid phase epitaxial regrowth (SPER) process of implantation amorphized Si0.7Ge0.3 layers (850± Å thick) grown on (100) Si has been studied by cross-sectional transmission electron microscopy. For amorphous layers produced by 40 Ar+ implantation highly defective three dimensional regrowth was observed in both Si0.7Ge0.3 and Si. Stacking faults were the principle defect formed of both materials during regrowth. SPER after amorphization via 73 Ge+ implantation was also investigated. It was found that the SPER velocity of the 73 Ge+ implanted Si0.7 Ge0.7 Ge0.3 was about twice the velocity of the 40 Ar+ implanted samples; for 73 Ge+ implanted Si it was about three times that of the 40Ar+ implanted samples. The activation energy for SPER in 40Ar+ and in 73 Ge+ implanted Si0.7 Geo0.3 was about 1.6 and 2.6 eV, respectively. The defect density was significantly reduced in 73 Ge+ amorphized Si but not in the 73 Ge+ amorphized Si0.7 Ge0.3. It is proposed that limited Ar solubility inhibits high quality regrowth in both SiGe and Si. Upon 73 Ge+ amorphization and solid phase epitaxy the interfacial strain between the SiGe and Si cannot be accommodated. Thus the epitaxial process is poor in these SiGe strained layers regardless of the amorphizing species.

Enamel Crystal Shape: History of an Idea

1987 ◽  
Vol 1 (2) ◽  
pp. 322-329 ◽  
Author(s):  
H. Warshawsky
Keyword(s):  
Electron Microscopy ◽  
Transmission Electron Microscopy ◽  
Cross Sections ◽  
Three Dimensional ◽  
Unit Cell ◽  
Cross Sectional ◽  
Transmission Electron ◽  
History Of ◽  
Sectional Shape ◽  
Imaging Plane

The purpose of this paper is to review evidence which casts doubt on the interpretation universally applied to hexagonal images seen in sectioned enamel. The evidence is based on two possible models to explain the hexagonal profiles seen in mammalian enamel with transmission electron microscopy. The "hexagonal ribbon" model proposes that hexagonal profiles are true cross-sections of elongated hexagonal ribbons. The "rectangular ribbon" model proposes that hexagonal profiles are caused by three-dimensional segments that are parallelepipeds contained in the Epon section. Since shadow projections of such rectangular segments give angles that are inconsistent with the hexagonal unit cell, a model based on ribbons with rhomboidal cut ends and angles of 60 and 120° is proposed. The "rhomboidal ribbon" model projects shadows with angles that are predicted by the unit cell. It is suggested that segments of such crystallites in section project as opaque hexagons on the imaging plane in routine transmission electron microscopy. Morphological observations on crystallites in sections - together with predictions from the hexagonal, rectangular, and rhomboidal ribbon models - indicate that crystallites in rat incisor enamel are flat ribbons with rhomboidal cross-sectional shape. Hexagonal images in electron micrographs of thin-sectioned enamel can result from rhomboidal-ended, parallelepiped-shaped segments of these crystallites projected and viewed as two-dimensional shadows.

Characterization of pulsed laser deposited MoS2 by transmission electron microscopy

1993 ◽  
Vol 8 (11) ◽  
pp. 2933-2941 ◽  
Author(s):  
S.D. Walek ◽  
M.S. Donley ◽  
J.S. Zabinski ◽  
V.J. Dyhouse
Keyword(s):  
Electron Microscopy ◽  
Thin Films ◽  
Transmission Electron Microscopy ◽  
Solid Phase ◽  
Analytical Electron Microscopy ◽  
Pulsed Laser ◽  
Cross Sectional ◽  
Aerospace Applications ◽  
Transmission Electron ◽  
Novel Method

Molybdenum disulfide is a technologically important solid phase lubricant for vacuum and aerospace applications. Pulsed laser deposition of MoS2 is a novel method for producing fully dense, stoichiometric thin films and is a promising technique for controlling the crystallographic orientation of the films. Transmission electron microscopy (TEM) of self-supporting thin films and cross-sectional TEM samples was used to study the crystallography and microstructure of pulsed laser deposited films of MoS2. Films deposited at room temperature were found to be amorphous. Films deposited at 300 °C were nanocrystalline and had the basal planes oriented predominately parallel to the substrate within the first 12–15 nm of the substrate with an abrupt upturn into a perpendicular (edge) orientation farther from the substrate. Spherically shaped particles incorporated in the films from the PLD process were found to be single crystalline, randomly oriented, and less than about 0.1 μm in diameter. A few of these particles, observed in cross section, had flattened bottoms, indicating that they were molten when they arrived at the surface of the growing film. Analytical electron microscopy (AEM) was used to study the chemistry of the films. The x-ray microanalysis results showed that the films have the stoichiometry of cleaved single crystal MoS2 standards.

High Resolution Transmission Electron Microscopy of Proton Implanted Gallium Arsenide

1985 ◽  
Vol 46 ◽  
Author(s):  
D. K. Sadana ◽  
J. M. Zavada ◽  
H. A. Jenkinson ◽  
T. Sands
Keyword(s):  
Electron Microscopy ◽  
Transmission Electron Microscopy ◽  
High Resolution ◽  
Phenomenological Model ◽  
Room Temperature ◽  
Stacking Faults ◽  
High Dose ◽  
Cross Sectional ◽  
Projected Range ◽  
Transmission Electron

AbstractHigh resolution transmission electron microscopy (HRTEM) has been performed on cross-sectional specimens from high dose (1016 cm−2) H+ implanted (100) GaAs (300 keV at room temperature). It was found that annealing at 500°C created small (20-50Å) loops on {111} near the projected range (Rp)(3.2 μm). At 550-600°C, voids surrounded by stacking faults, microtwins and perfect dislocations were observed near the Rp. A phenomenological model explaining the observed results is proposed.

Tem Study of the Structure of Mbe GaAs Layers Grown at Low Temperature

1990 ◽  
Vol 198 ◽  
Author(s):  
Zuzanna Liliental-Weber
Keyword(s):  
Electron Microscopy ◽  
Low Temperature ◽  
Molecular Beam ◽  
Critical Thickness ◽  
Stacking Faults ◽  
Structural Quality ◽  
Crystalline Perfection ◽  
Transmission Electron ◽  
Low Temperature Gaas

ABSTRACTThe structural quality of GaAs layers grown at 200°C by molecular beam epitaxy (MBE) was investigated by transmission electron microscopy (TEM). We found that a high crystalline perfection can be achieved in the layers grown at this low temperature for thickness up to 3 μm. In some samples we observed pyramid-shaped defects with polycrystalline cores surrounded by microtwins, stacking faults and dislocations. The size of these cores increased as the growth temperature was decreased and as the layer thickness was increased. The upper surface of layers with pyramidal defects became polycrystalline at a critical thickness of the order of 3μm. We suggested that the low-temperature GaAs becomes polycrystalline at a critical thickness either because of a decrease in substrate temperature during growth or because strain induced by excess As incorporated in these layers leads to the formation of misoriented GaAs nuclei, thereby initiating polycrystalline growth. The pyramidal shape of the defects results from a growth-rate hierarchy of the low index planes in GaAs.

scholarly journals Oblique Stacking of Three-Dimensional Dome Islands in Ge/Si Multilayers

2000 ◽  
Vol 648 ◽  
Author(s):  
P. Sutter ◽  
E. Sutter ◽  
L. Vescan
Keyword(s):  
Electron Microscopy ◽  
Transmission Electron Microscopy ◽  
Three Dimensional ◽  
Surface Curvature ◽  
Surface Strain ◽  
Complex Interplay ◽  
Cross Sectional ◽  
Transmission Electron ◽  
Planar Substrate ◽  
Inherent Tendency

AbstractThe organization of Ge ‘dome’ islands in Ge/Si multilayers has been investigated by cross-sectional transmission electron microscopy. Ge ‘domes’ are found to spontaneously arrange in oblique stacks, replicating at a well-defined angle from one bilayer to the next. The formation of oblique island stacks is governed by a complex interplay of surface strain - generated by the already buried islands - and surface curvature - caused by the inherent tendency of large ‘domes’ to carve out material from the surrounding planar substrate.

Si1-xGex Critical Thickness for Surface Wave Generation During UHV-CVD Growth at 525°C

1995 ◽  
Vol 399 ◽  
Author(s):  
H. Lafontaine ◽  
D.C. Houghton ◽  
B. Bahierathan ◽  
D.D. Perovic ◽  
J.-M. Baribeau
Keyword(s):  
Electron Microscopy ◽  
Surface Waves ◽  
Critical Thickness ◽  
Critical Value ◽  
Misfit Dislocations ◽  
Cross Sectional ◽  
Force Microscopy ◽  
Atomic Force ◽  
Transmission Electron ◽  
Cvd Growth

ABSTRACTSeveral Si1-xGex/Si heterostructures were grown at 525°C using a commercially available UHV-CVD reactor. Layers with a germanium fraction ranging from 0.15 to 0.5 were examined by means of cross-sectional transmission electron microscopy and atomic force microscopy. Surface waves were found in layers with a thickness above a critical value which decreases rapidly as the Ge fraction is increased. Both experimental and modeling results show that surface waves are generated before misfit dislocations for Ge fractions above 0.3.

Ohmic Contact Formation Mechanism in the Ge/Pd/N-GaAs System

1989 ◽  
Vol 148 ◽  
Author(s):  
E.D. Marshall ◽  
S.S. Lau ◽  
C.J. Palmstrøm ◽  
T. Sands ◽  
C.L. Schwartz ◽  
...  
Keyword(s):  
Electron Microscopy ◽  
Mass Spectrometry ◽  
Secondary Ion Mass Spectrometry ◽  
Solid Phase ◽  
Cross Sectional ◽  
Ohmic Behavior ◽  
Transmission Electron ◽  
Solid Phase Regrowth ◽  
Ohmic Contact Formation ◽  
Secondary Ion

ABSTRACTAnnealed Ge/Pd/n-GaAs samples utilizing substrates with superlattice marker layers have been analyzed using high resolution backside secondary ion mass spectrometry and cross-sectional transmission electron microscopy. Interfacial compositional and microstructural changes have been correlated with changes in contact resistivity. The onset of good ohmic behavior is correlated with the decomposition of an intermediate epitaxial Pd4(GaAs,Ge2) phase and solid-phase regrowth of Ge-incorporated GaAs followed by growth of a thin Ge epitaxial layer.

In-Situannealing Transmission Electron Microscopy(Tem) Study of the Ti/GaAs Interfacial Reactions

1989 ◽  
Vol 148 ◽  
Author(s):  
Ki-Bum Kim ◽  
Robert Sinclair
Keyword(s):  
Electron Microscopy ◽  
Gaas Substrate ◽  
Metal Film ◽  
Interfacial Reactions ◽  
Cross Sectional ◽  
Plan View ◽  
Transmission Electron ◽  
Initial Stage ◽  
Random Manner

ABSTRACTIn-situ annealing TEM experiments were performed on the Ti/GaAs system in order to study the dynamic behavior of interfacial reactions. Both plan-view and cross-sectional samples were investigated in either diffraction and imaging (both conventional and high resolution) modes. During experiments, we observed the following: (a) At the initial stage of reaction, the TiAs phase formed at the original Ti/GaAs interface with a distinct orientation with respect to the substrate; (b) as the reaction proceeded, the TiAs phase formed in a random manner; (c) finally, the liberated Ga species from the GaAs diffused out to the metal film and formed TiGa2 phase in the plan-view sample similar to the furnace-annealed case. For the cross-sectional sample, however, we did not observe any Ti:Ga phase formation. Instead, we observed the formation of voids both in the Ti film and in the GaAs substrate. The formation of different microstructure between in-situ and furnace annealed cases is explained by the sample geometry during annealing.

XTEM microscopy of martensitic transformations in noble gas implanted stainless steel

1990 ◽  
Vol 48 (4) ◽  
pp. 206-207
Author(s):  
E. Johnson ◽  
A. Johansen ◽  
L. Sarholt-Kristensen ◽  
E. Gerritsen ◽  
J. Politiek ◽  
...  
Keyword(s):  
Electron Microscopy ◽  
Transmission Electron Microscopy ◽  
Stainless Steels ◽  
Solid Phase ◽  
Noble Gas ◽  
Thick Layer ◽  
Austenitic Stainless Steels ◽  
Martensitic Transformations ◽  
Cross Sectional ◽  
Transmission Electron

Cross-sectional transmission electron microscopy (XTEM) has been used to study the microstructure of noble gas implanted austenitic stainless steels, and in particular to analyse the depth distribution of implantation induced martensite in relation to the general radiation damage distribution.Large discs of low-austenitic stainless steels have been ion implanted with noble gases to fluences in the range l.1020 - 1.1021 m-2. Samples of the implanted discs for cross-sectional transmission electron microscopy (XTEM) were made by electroplating the implanted surface with a 3 mm thick layer of nickel, cutting 3 mm discs from the interface and electropolishing the discs to perforation using a Struers TENUPOL immersion jet apparatus.In samples implanted with low fluences (1-1020 m-2) the implantation zone consists of a heavily damaged top layer containing a dense distribution of microscopic noble gas inclusions, which are visible in defocusing phase contrast. The inclusions are ∽ 3-5 nm in diameter, and the smallest inclusions contain noble gas in the solid phase.

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