Studies of In0.53Ga0.47As/InP Superlattice Mixing and Conversion

1988 ◽  
Vol 144 ◽  
Author(s):  
S.A. Schwarz ◽  
P. Mei ◽  
D.M. Hwang ◽  
C.L. Schwartz ◽  
T. Venkatesan ◽  
...  
Keyword(s):  
Secondary Ion Mass Spectrometry ◽  
Threshold Concentration ◽  
High Dose ◽  
Cation Site ◽  
Transmission Electron Microscopy Micrographs ◽  
Strained Layers ◽  
Transmission Electron ◽  
The Difference ◽  
Si Films ◽  
Highly Strained

ABSTRACTSealed ampoule Zn diffusions into an unstrained In0.53Ga0.47As/InP superlattice are observed to preferentially induce cation (In, Ga) interdiffusion. The extent of interdiffusion is monitored in these studies by SIMS (secondary ion mass spectrometry). In some cases, Zn entirely displaces In in the InP layers forming an In1−xGaxAs/Zn3P2 superlattice. Under still more stringent conditions, all In and Ga is replaced, resulting in a Zn3As2/Zn3P2 superlattice. These structures are capable of supporting considerable strain due to the absence of grown-in defects. TEM (transmission electron microscopy) micrographs of several samples reveal defect free highly strained layers with thicknesses exceeding the predicted critical values. A high dose Zn implant was examined in which mixing proceeded until the Zn concentration dropped below a threshold concentration of approximately 1020 cm−3 during the anneal. These results, in total, strongly support a kickout mechanism for Zn induced mixing. Si diffusion was observed, in one case, to induce comparable cation and anion interdiffusion, thereby reducing the layer bandgap disparity, as opposed to Zn which increases the difference in layer bandgaps. Almost no interdiffusion was induced by Si diffusion from MBE (molecular beam epitaxy) polycrystalline Si films, due either to the very high resultant Si concentrations or to the capping effect of the film. The data suggest that both anion and cation site defects play a role in the Si induced mixing process.

Composition and Strain Analysis of Semiconductor Heterostructures Using Thickness Fringes on Tem Images

1994 ◽  
Vol 332 ◽  
Author(s):  
H. Kakibayashi ◽  
R. Tsuneta ◽  
F. Nagata
Keyword(s):  
Multiple Quantum Well ◽  
Strain Analysis ◽  
Dynamical Theory ◽  
Multiple Quantum ◽  
Strained Layers ◽  
Quantum Well Structures ◽  
Depth Profiles ◽  
Transmission Electron ◽  
The Difference ◽  
Induced Defects

ABSTRACTComposition and strain depth profiles in heterostructures such as AlGaAs/GaAs, InGaAs/InP and SiGe/Si have been analyzed with a high resolution of 0.5 nm by using the thickness fringes in a transmission electron microscope image. This diagnostic method is found to successfully evaluate the compositional disordering caused by annealing multiple quantum well structures with abrupt interfaces, and determine the difference in strain distribution in the strained-layers with various lattice mismatches. Both the composition and strain depth-profiles are analyzed quantitatively by the image simulation based on the dynamical theory of electron diffraction. This method is also useful for sensitively detecting ion-implantation-induced defects.

Damage Removal Processes in Ion Implanted, Rapidly Annealed GaAs

1985 ◽  
Vol 52 ◽  
Author(s):  
D. C. Jacobson ◽  
S. J. Pearton ◽  
R. Hull ◽  
J. M. Poate ◽  
J. S. Williams
Keyword(s):  
Carrier Mobility ◽  
Secondary Ion Mass Spectrometry ◽  
High Dose ◽  
Electrical Characteristics ◽  
Dislocation Loops ◽  
Transmission Electron ◽  
Capacitance Voltage ◽  
Lattice Damage ◽  
Removal Processes ◽  
Secondary Ion

ABSTRACTThe removal of lattice damage and consequent activation by rapid thermal annealing of implanted Si, Se, Zn and Be in GaAs was investigated by capacitance-voltage profiling, Hall measurements, transmission electron microscopy (TEM), secondary ion mass spectrometry and Rutherford backscattering. The lighter species show optimum electrical characteristics at lower annealing temperatures (˜850°C for Be, ˜950°C for Si) than the heavier species (˜900°C for Zn, ˜1000°C for Se), consistent with the amount of lattice damage remaining after annealing. TEM reveals the formation of high densities (107 cm−2) of dislocation loops after 800°C, 3s anneals of high dose (1×1015 cm−2) implanted GaAs, which are gradually reduced in density after higher temperatures anneals (˜1000°C). The remaining loops do not appear to effect the electrical activation or carrier mobility in the implanted layer, the latter being comparable to bulk values.

Ftir Spectroscopy and Spectroscopic Ellipsometry Study of Nanocrystalline Layers Formed by High-Dose Hydrogen and Deuterium Implantation of Silicon

2000 ◽  
Vol 609 ◽  
Author(s):  
L.N. Safronov ◽  
E.V. Spesivtsev ◽  
V.P. Popov ◽  
I.V. Antonova ◽  
A.K. Gutakovskii ◽  
...  
Keyword(s):  
Ftir Spectroscopy ◽  
Spectroscopic Ellipsometry ◽  
Secondary Ion Mass Spectrometry ◽  
Crystalline Silicon ◽  
Silicon Layer ◽  
High Dose ◽  
Ir Absorption ◽  
Hydrogen Atoms ◽  
High Hydrogen ◽  
Transmission Electron

ABSTRACTStructural study of a-Si layers formed by high fluence hydrogen or deuterium implantation (up to 5×1017 cm−2) using high current beams with means of current up 40 mA/cm2 was carried out in the present work. The Si:H(D) silicon films were characterized using FTIR spectroscopy, spectroscopic ellipsometry, transmission electron microscopy and secondary ion mass spectrometry. Hydrogen solubility in crystalline silicon is low but ion implantation allows one to introduce hydrogen atoms in the concentration of 1022cm−3 or even more in thin silicon layer. High defect concentration in combination with high hydrogen activity causes the formation of mixed amorphous and crystalline phases with structure similar to silicon produced PECVD or laser ablation. The transformation of optical properties of this film during annealing in temperature range of 200-1050°C was investigated. The changes in optical characteristics and number of Si-H or Si-D bonds in the spectra of IR absorption is correlated with increase in crystalline volume of silicon with a temperature.

Mn Implantation for New Applications of 4H-SiC

2012 ◽  
Vol 717-720 ◽  
pp. 221-224 ◽  
Author(s):  
Margareta K. Linnarsson ◽  
Jennifer Wong-Leung ◽  
Anders Hallén ◽  
S.I. Khartsev ◽  
A.M. Grishin
Keyword(s):  
Electron Microscopy ◽  
Heat Treatment ◽  
Near Infrared ◽  
Secondary Ion Mass Spectrometry ◽  
Stacking Faults ◽  
Structural Disorder ◽  
High Dose ◽  
Transmission Electron ◽  
New Applications ◽  
Secondary Ion

Structural disorder and lattice recovery of high dose, manganese implanted, semi-insulating, 4H-SiC have been studied by secondary ion mass spectrometry, Rutherford backscattering in channeling directions, visible-to-near infrared optical spectroscopy as well as with transmission electron microscopy. After heat treatment at 1400 and 1600 °C, a substantial rearrangement of manganese is observed in the implanted region. However, the crystal has not been fully recovered. More disorder remains in the [11 3] compared to the [0001] channel direction. Stacking faults, voids and 3C inclusions are observed in the implanted region. A Mn containing phase has most likely formed.

Fabrication and Evaluation of Ternary Co-Fe-Si Structures Produced by Ion Beam Synthesis

1992 ◽  
Vol 279 ◽  
Author(s):  
Tim D. Hunt ◽  
Brian J. Sealy ◽  
Jochen Hanebeck ◽  
Karen J. Reeson ◽  
Kevin P. Homewood ◽  
...  
Keyword(s):  
Single Phase ◽  
Low Dose ◽  
Secondary Ion Mass Spectrometry ◽  
Ion Beam ◽  
Single Species ◽  
High Dose ◽  
Cross Sectional ◽  
Transmission Electron ◽  
Secondary Ion

ABSTRACTDual implantation of cobalt and iron into silicon (100) wafers and subsequent annealing has been used to form layers containing mixtures of CoSi2 and FeSi2. The structure and properties of the layers were followed by Secondary Ion Mass Spectrometry (SIMS), cross-sectional transmission electron microscopy (XTEM), Transmission Electron Diffraction (TED), Rutherford Backscattering Spectroscopy (RBS), and photoluminescence (PL). When a high dose of both species was implanted, segregation of the cobalt and iron occurred which for 1000°C anneals, resulted in an epitaxial layer of αFeSi2 upon a CoSi2 layer. The epitaxial quality of both of these layers was superior to those previously fabricated by single species implants. For a low dose cobalt implant followed by a high dose iron implant, a single phase solid solution was formed and segregation did not occur. Photoluminescence at 1.54 urn was observed from this layer, but with a much lower intensity and a broader line width than that from a pure βFeSi2 layer.

Influence of Cell Wall Composition on the Fossilisation of Bacteria and the Implications for the Search for Early Life Forms

1997 ◽  
Vol 161 ◽  
pp. 491-504 ◽  
Author(s):  
Frances Westall
Keyword(s):  
Cell Wall ◽  
Life Forms ◽  
Cation Binding ◽  
Positive Bacterium ◽  
Gram Positive ◽  
Gram Positive Bacteria ◽  
Transmission Electron ◽  
Hydrothermal Sediments ◽  
Identification Of Bacteria ◽  
The Difference

AbstractThe oldest cell-like structures on Earth are preserved in silicified lagoonal, shallow sea or hydrothermal sediments, such as some Archean formations in Western Australia and South Africa. Previous studies concentrated on the search for organic fossils in Archean rocks. Observations of silicified bacteria (as silica minerals) are scarce for both the Precambrian and the Phanerozoic, but reports of mineral bacteria finds, in general, are increasing. The problems associated with the identification of authentic fossil bacteria and, if possible, closer identification of bacteria type can, in part, be overcome by experimental fossilisation studies. These have shown that not all bacteria fossilise in the same way and, indeed, some seem to be very resistent to fossilisation. This paper deals with a transmission electron microscope investigation of the silicification of four species of bacteria commonly found in the environment. The Gram positiveBacillus laterosporusand its spore produced a robust, durable crust upon silicification, whereas the Gram negativePseudomonas fluorescens, Ps. vesicularis, andPs. acidovoranspresented delicately preserved walls. The greater amount of peptidoglycan, containing abundant metal cation binding sites, in the cell wall of the Gram positive bacterium, probably accounts for the difference in the mode of fossilisation. The Gram positive bacteria are, therefore, probably most likely to be preserved in the terrestrial and extraterrestrial rock record.

Destruction of Actin Filaments by Osmium Tetroxide

1977 ◽  
Vol 35 ◽  
pp. 466-467
Author(s):  
P. Maupin-Szamier ◽  
T. D. Pollard
Keyword(s):  
Actin Filaments ◽  
Time Course ◽  
Osmium Tetroxide ◽  
Rabbit Muscle ◽  
Muscle Actin ◽  
Sodium Phosphate Buffer ◽  
Transmission Electron ◽  
The Difference ◽  
Rates Of Decay ◽  
Short Time

We have studied the destruction of rabbit muscle actin filaments by osmium tetroxide (OSO4) to develop methods which will preserve the structure of actin filaments during preparation for transmission electron microscopy.Negatively stained F-actin, which appears as smooth, gently curved filaments in control samples (Fig. 1a), acquire an angular, distorted profile and break into progressively shorter pieces after exposure to OSO4 (Fig. 1b,c). We followed the time course of the reaction with viscometry since it is a simple, quantitative method to assess filament integrity. The difference in rates of decay in viscosity of polymerized actin solutions after the addition of four concentrations of OSO4 is illustrated in Fig. 2. Viscometry indicated that the rate of actin filament destruction is also dependent upon temperature, buffer type, buffer concentration, and pH, and requires the continued presence of OSO4. The conditions most favorable to filament preservation are fixation in a low concentration of OSO4 for a short time at 0°C in 100mM sodium phosphate buffer, pH 6.0.

Electron Energy Analysis of Germanium and Silica Layers on Silicon Substrates

1975 ◽  
Vol 33 ◽  
pp. 96-97
Author(s):  
R. W. Ditchfield ◽  
A. G. Cullis
Keyword(s):  
Epitaxial Growth ◽  
Electron Energy ◽  
Silicon Substrates ◽  
Secondary Phases ◽  
Si Substrates ◽  
Transmission Electron ◽  
Layer Structures ◽  
Si Films ◽  
Electron Energy Loss ◽  
Growth Centres

An energy analyzing transmission electron microscope of the Möllenstedt type was used to measure the electron energy loss spectra given by various layer structures to a spatial resolution of 100Å. The technique is an important, method of microanalysis and has been used to identify secondary phases in alloys and impurity particles incorporated into epitaxial Si films.Layers Formed by the Epitaxial Growth of Ge on Si Substrates Following studies of the epitaxial growth of Ge on (111) Si substrates by vacuum evaporation, it was important to investigate the possible mixing of these two elements in the grown layers. These layers consisted of separate growth centres which were often triangular and oriented in the same sense, as shown in Fig. 1.

Growth of near noble metal Pd and Pt thin film silicides morphology and structure

1984 ◽  
Vol 42 ◽  
pp. 498-499
Author(s):  
E. I. Alessandrini ◽  
M. O. Aboelfotoh
Keyword(s):  
Noble Metals ◽  
Annealing Temperature ◽  
Chemical Compounds ◽  
Barrier Properties ◽  
Solid State Reactions ◽  
Transmission Electron ◽  
Stable Chemical ◽  
Metal Thickness ◽  
Amorphous Si ◽  
Si Films

Considerable interest has been generated in solid state reactions between thin films of near noble metals and silicon. These metals deposited on Si form numerous stable chemical compounds at low temperatures and have found applications as Schottky barrier contacts to silicon in VLSI devices. Since the very first phase that nucleates in contact with Si determines the barrier properties, the purpose of our study was to investigate the silicide formation of the near noble metals, Pd and Pt, at very thin thickness of the metal films on amorphous silicon.Films of Pd and Pt in the thickness range of 0.5nm to 20nm were made by room temperature evaporation on 40nm thick amorphous Si films, which were first deposited on 30nm thick amorphous Si3N4 membranes in a window configuration. The deposition rate was 0.1 to 0.5nm/sec and the pressure during deposition was 3 x 10 -7 Torr. The samples were annealed at temperatures in the range from 200° to 650°C in a furnace with helium purified by hot (950°C) Ti particles. Transmission electron microscopy and diffraction techniques were used to evaluate changes in structure and morphology of the phases formed as a function of metal thickness and annealing temperature.

Microprobe analysis of inclusion bodies related to two benzofuran derivatives

1987 ◽  
Vol 45 ◽  
pp. 672-673
Author(s):  
T. L. Benning ◽  
P. Ingram ◽  
J. D. Shelburne
Keyword(s):  
Inclusion Bodies ◽  
Uranyl Acetate ◽  
Multiple Organ ◽  
High Dose ◽  
En Bloc ◽  
Tissue Samples ◽  
Transmission Electron ◽  
Organ Systems ◽  
Dense Inclusion ◽  
Melanin Complex

Two benzofuran derivatives, chlorpromazine and amiodarone, are known to produce inclusion bodies in human tissues. Prolonged high dose chlorpromazine therapy causes hyperpigmentation of the skin with electron-dense inclusion bodies present in dermal histiocytes and endothelial cells ultrastructurally. The nature of the deposits is not known although a drug-melanin complex has been hypothesized. Amiodarone may also cause cutaneous hyperpigmentation and lamellar lysosomal inclusion bodies have been demonstrated within the cells of multiple organ systems. These lamellar bodies are believed to be the product of an amiodarone-induced phospholipid storage disorder. We performed transmission electron microscopy (TEM) and energy dispersive x-ray microanalysis (EDXA) on tissue samples from patients treated with these drugs, attempting to detect the sulfur atom of chlorpromazine and the iodine atom of amiodarone within their respective inclusion bodies.A skin biopsy from a patient with hyperpigmentation due to prolonged chlorpromazine therapy was fixed in 4% glutaraldehyde and processed without osmium tetroxide or en bloc uranyl acetate for Epon embedding.

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