The Energy Dependence of Ion Damage in A1xGa1−xAs/GaAs HETErostructures and The Effects of Implanted Impurity

1991 ◽  
Vol 235 ◽  
Author(s):  
A. G. Cullis ◽  
D. C. Jacobson ◽  
A. Polman ◽  
P. W. Smith ◽  
J. M. Poate ◽  
...  
Keyword(s):  
Gaas Layer ◽  
Local Concentration ◽  
Significant Protection ◽  
Damage Resistance ◽  
Ion Channeling ◽  
Transmission Electron ◽  
Layer Structures ◽  
Ion Damage ◽  
Lattice Damage ◽  
First Time

ABSTRACTBombardment damage produced by Si+ ions in AlxGa1−xAs/GaAs layer structures has been studied using transmission electron microscopy and ion channeling and backscattering spectrometry. The damage resistance of A1xGa1−xAs alloy layers increases with Al concentration. In particular, by comparison of complementary Si+ ion doses yielding similar nuclear displacement densities at 150keV and 2MeV bombardment energies, it is demonstrated for the first time that the local concentration of implanted Si impurity is likely to be a significant factor in controlling lattice damage build-up, especially for the highest Si+ ion implantation doses. It is also shown that, in a manner analogous to A1As, the alloy layers can confer a significant protection from ion damage upon adjacent, epitaxially-bonded narrow zones of crystalline GaAs.

Growth and Characterizations of Gaas on Inp with Different Buffer Structures by Molecular Beam Epitaxy

1989 ◽  
Vol 148 ◽  
Author(s):  
Xiaoming Liu ◽  
Henry P. Lee ◽  
Shyh Wang ◽  
Thomas George ◽  
Eicke R. Weber ◽  
...  
Keyword(s):  
Low Temperature ◽  
Buffer Layer ◽  
Gaas Layer ◽  
Optical Quality ◽  
Cross Sectional ◽  
Transmission Electron ◽  
Layer Structures ◽  
Gaas Films ◽  
Initial Deposition ◽  
Strained Layer Superlattices

ABSTRACTWe report the growth and characterizations of 31μm thick GaAs films grown on (100) InP substrates by MBE employing different buffer layer structures during the initial deposition. The buffer layer structures under study are: 1) GaAs layer grown at low temperature; 2) GaAs layer grown at low temperature plus two sets of In0.08Ga0.92As/GaAs strained layer superlattices (SLS) and 3) a transitional compositionally graded InxGal-xAs layer between the InP substrate and the GaAs film. After the buffer layer deposition, the growth was continued by conventionalMBE to a total thickness of 3μm for all samples. From the 77K photoluminescence (PL) measurement, it was found that the sample with SLS layers has the highest PL intensity and the narrowest PL linewidth. Cross-sectional transmission electron microscopy (TEM) studies showed that the SLS is effective in reducing the propagation of threading dislocations and explains the observed superior optical quality from the PL measurement.

Stratified Ion Damage and in Situ Regrowth in GaAs/AlAs Heterostructures

1990 ◽  
Vol 201 ◽  
Author(s):  
A G Cullis ◽  
D J Eaglesham ◽  
D C Jacobson ◽  
J M Poate ◽  
C R Whitehouse ◽  
...  
Keyword(s):  
Electron Microscopy ◽  
Point Defects ◽  
Multilayer Structures ◽  
Dependent Manner ◽  
Characteristic Boundary ◽  
Transmission Electron ◽  
Wide Range ◽  
Ion Damage ◽  
Lattice Damage

AbstractThe material-dependent manner in which ion damage occurs in AlAs/GaAs heteroepitaxial structures is demonstrated using conventional and high resolution transmission electron microscopy. Both 150keV and 2MeV Si+ ion implants are employed over a wide range of ion doses. Under conditions which yield rapid build-up of lattice damage in GaAs, the AlAs is found to be relatively resistant to structure breakdown. Indeed, the crystalline AlAs exerts a novel protective effect on immediately adjacent regions of the GaAs layers. For high implantation doses amorphous-crystal superlattices are formed in multilayer structures. For the highest ion doses the AlAs lattice begins to be disrupted by a characteristic, boundary-dependent, heterogeneous mechanism. These observations suggest that mobile point defects play a significant role in AlAs in situ restructuring processes.

Ion Beam Synthesis of IrSi3 by Implantation of 2 MeV Ir Ions+

1992 ◽  
Vol 279 ◽  
Author(s):  
T. P. Sjoreen ◽  
H.-J. Hinneberg ◽  
M. F. Chisholm
Keyword(s):  
Substrate Temperature ◽  
Ion Beam ◽  
Layer Formation ◽  
Cross Sectional ◽  
Implantation Energy ◽  
Precipitate Coarsening ◽  
Ion Channeling ◽  
Transmission Electron ◽  
Lattice Damage ◽  
Substrate Temperatures

ABSTRACTThe formation of a buried IrSi3 layer in (111) oriented Si by ion implantation and annealing has been studied at an implantation energy of 2 MeV for substrate temperatures of 450–550°C. Rutherford backscattering (RBS), ion channeling and cross-sectional transmission electron microscopy showed that a buried epitaxial IrSi3 layer is produced at 550°C by implanting ≥ 3.4 × 1017 Ir/cm2 and subsequently annealing for 1 h at 1000°C plus 5 h at 1100°C. At a dose of 3.4 × 1017 Ir/cm2, the thickness of the layer varied between 120 and 190 nm and many large IrSi3 precipitates were present above and below the film. Increasing the dose to 4.4 × 1017 Ir/cm2 improved the layer uniformity at the expense of increased lattice damage in the overlying Si. RBS analysis of layer formation as a function of substrate temperature revealed the competition between the mechanisms for optimizing surface crystallinity vs. IrSi3 layer formation. Little apparent substrate temperature dependence was evident in the as-implanted state but after annealing the crystallinity of the top Si layer was observed to deteriorate with increasing substrate temperature while the precipitate coarsening and coalescence improved.

Complex Layer Stacking In Muscovite: A Hrtem Study

1999 ◽  
Vol 5 (S2) ◽  
pp. 152-153
Author(s):  
Chi Ma ◽  
George R. Rossman
Keyword(s):  
Electron Microscopy ◽  
Short Range ◽  
Analytical Electron Microscopy ◽  
Disordered Structures ◽  
Transmission Electron ◽  
Layer Structures ◽  
Layer Stacking ◽  
Disordered Layer ◽  
Sheet Silicate ◽  
First Time

One-, two- and three-layer polytypes are common in muscovite (sheet silicate). Based on high-resolution transmission electron microscopy (HRTEM) and analytical electron microscopy (AEM) examinations, we report in the discovery of complex 5-layer and 7- layer polytypes in natural muscovite for the first time (Fig. 1) and the implications of polytype transitions.Three main structures are found in muscovite crystals in a sample from Oreana, Nevada, which are 1M, 2M1, and a disordered structure often containing short-range ordered stacking sequences. On the scale of a few micrometers, muscovite occurs as ordered crystals, disordered crystals, and crystals with regions of ordered and disordered layer stacking.Short-range ordered 5- or 7-layer repeats are found in some disordered structures where single 4-, 6-, 9- or 10-layer intergrowths occur occasionally with 2- and 3-layer repeats. Such complex polytypes have not been observed before in either natural or synthetic muscovite, although 5- and 7-layer structures are commonly present in trioctahedral micas (i.e., biotite) (Baronnet, 1992).

Interfacial Reactions of Co and Si/Co Films on GaAs

1994 ◽  
Vol 337 ◽  
Author(s):  
J. S. Kwak ◽  
H. K. Baik ◽  
J. I. Lee ◽  
S. K. Noh ◽  
D. W. Shin ◽  
...  
Keyword(s):  
Ternary Phase ◽  
Gaas Layer ◽  
Interfacial Reactions ◽  
X Ray Diffraction ◽  
Subsequent Reaction ◽  
Cross Sectional ◽  
Quaternary Phase ◽  
Transmission Electron ◽  
Layer Structures ◽  
Higher Temperature

ABSTRACTInterfacial reactions of Co and Si/Co films on GaAs have been investigated using X-ray diffraction(XRD), Auger electron spectroscopy(AES), cross-sectional transmission electron microscopy(XTEM), microdiffraction, and energy dispersive spectroscopy(EDS). Cobalt starts to react with GaAs at 380°C by formation of ternary phase, most probably Co2GaAs. At 420°C, CoGa nucleates at the Co and Co2GaAs interface and grows with Co2GaAs. At higher temperature, Co2GaAs disappears and CoGa/GaAs layer structures are formed. Annealing of the layer-deposited Si/Co films at 380°C results in the formation of Co2GaAs. At 420°C, the entire layer of Co is consumed, while Co2Si transforms to CoSi, and binary phases, CoGa and CoAs, are formed on top of the ternary phase beneath the CoSi layer. In the subsequent reaction, CoSi grows at the expense of the decompositions of CoGa and CoAs at 460°C. At 600°C, ternary phase is decomposed, and CoSi forms interface with GaAs. This finding can be understood from the calculated Si-Co-Ga-As quaternary phase diagram.

Spontaneous Crystalline Multilayer Formation in Ni Implanted Al at 100 K

2000 ◽  
Vol 647 ◽  
Author(s):  
Alexandre Cuenat ◽  
Aicha Hessler-Wyser ◽  
Max Döbeli ◽  
Rolf Gotthardt
Keyword(s):  
Electron Microscopy ◽  
Transmission Electron Microscopy ◽  
Rutherford Backscattering Spectrometry ◽  
Local Concentration ◽  
Crystal Transformation ◽  
Transmission Electron ◽  
Recrystallization Front ◽  
Multilayer Formation ◽  
First Time ◽  
Sharp Interfaces

AbstractThe microstructure evolution of aluminum implanted with nickel at 5 MeV and at 100 K to a local concentration of 25 at. % is described. Transmission Electron Microscopy (TEM) observa- tions and Rutherford Backscattering Spectrometry (RBS) experiments are conducted to deter-mine the Ni profile and the microstructure of the implanted samples. For lower Ni concentration, it has been previously observed that Al0.75Ni0.25 amorphous precipitates are formed together with a high dislocation density. When the Ni concentration reaches 25 at. %, a new crystalline multi-layered microstructure is observed: the TEM observations reveal the presence of well-defined crystalline layers separated by sharp interfaces. To our knowledge, it is the first time that such a structure is observed without further annealing of the implanted sample. A series of mechanisms describing the formation of the crystalline multilayer are briefly discussed. It is argued that its formation is the result of a recrystallization front produced by the exothermal amorphous to crystal transformation.

Comparative Microstructures of Ion Milled and Electrochemically Thinned Composite Materials

1974 ◽  
Vol 32 ◽  
pp. 546-547
Author(s):  
R.R. Russell
Keyword(s):  
Electron Microscopy ◽  
Transmission Electron Microscopy ◽  
Composite Materials ◽  
Great Difficulty ◽  
Ion Milling ◽  
Transmission Electron ◽  
Ion Damage ◽  
Intermetallic Composite

Transmission electron microscopy of metallic/intermetallic composite materials is most challenging since the microscopist typically has great difficulty preparing specimens with uniform electron thin areas in adjacent phases. The application of ion milling for thinning foils from such materials has been quite effective. Although composite specimens prepared by ion milling have yielded much microstructural information, this technique has some inherent drawbacks such as the possible generation of ion damage near sample surfaces.

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.

A Novel TEM Technique for Characterizing As-Grown CVD Diamond Films

1991 ◽  
Vol 49 ◽  
pp. 956-957 ◽  
Author(s):  
Z.L. Wang ◽  
J. Bentley ◽  
R.E. Clausing ◽  
L. Heatherly ◽  
L.L. Horton
Keyword(s):  
Diamond Films ◽  
Chemical Vapor ◽  
Growth Direction ◽  
Dark Field ◽  
Growth Surface ◽  
Specimen Preparation ◽  
Transmission Electron ◽  
Diffraction Patterns ◽  
First Time ◽  
Microstructural Studies

Microstructural studies by transmission electron microscopy (TEM) of diamond films grown by chemical vapor deposition (CVD) usually involve tedious specimen preparation. This process has been avoided with a technique that is described in this paper. For the first time, thick as-grown diamond films have been examined directly in a conventional TEM without thinning. With this technique, the important microstructures near the growth surface have been characterized. An as-grown diamond film was fractured on a plane containing the growth direction. It took about 5 min to prepare a sample. For TEM examination, the film was tilted about 30-45° (see Fig. 1). Microstructures of the diamond grains on the top edge of the growth face can be characterized directly by transmitted electron bright-field (BF) and dark-field (DF) images and diffraction patterns.

scholarly journals Quartz Crystallite Size and Moganite Content as Indicators of the Mineralogical Maturity of the Carboniferous Chert: The Case of Cherts from Eastern Asturias (Spain)

Minerals ◽  
2021 ◽  
Vol 11 (6) ◽  
pp. 611
Author(s):  
Celia Marcos ◽  
María de Uribe-Zorita ◽  
Pedro Álvarez-Lloret ◽  
Alaa Adawy ◽  
Patricia Fernández ◽  
...  
Keyword(s):  
Electron Microscopy ◽  
Transmission Electron Microscopy ◽  
Crystallite Size ◽  
Archaeological Sites ◽  
X Ray Diffraction ◽  
X Ray ◽  
Transmission Electron ◽  
Infrared And Raman Spectroscopy ◽  
First Time ◽  
Geological Formations

Chert samples from different coastal and inland outcrops in the Eastern Asturias (Spain) were mineralogically investigated for the first time for archaeological purposes. X-ray diffraction, X-ray fluorescence, transmission electron microscopy, infrared and Raman spectroscopy and total organic carbon techniques were used. The low content of moganite, since its detection by X-ray diffraction is practically imperceptible, and the crystallite size (over 1000 Å) of the quartz in these cherts would be indicative of its maturity and could potentially be used for dating chert-tools recovered from archaeological sites. Also, this information can constitute essential data to differentiate the cherts and compare them with those used in archaeological tools. However, neither composition nor crystallite size would allow distinguishing between coastal and inland chert outcrops belonging to the same geological formations.

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