Synthesis of Si1-xGex-on-Insulator by 74Ge+ Ion Implantation in a Simox Substrate

1993 ◽  
Vol 316 ◽  
Author(s):  
C.J. Patel ◽  
C.D. Marsh ◽  
U. Magnusson ◽  
C. Jeynes ◽  
M. Ostling ◽  
...  
Keyword(s):  
Electron Microscopy ◽  
Heat Treatment ◽  
Defect Density ◽  
Rutherford Backscattering Spectrometry ◽  
Final Heat Treatment ◽  
Conductivity Measurements ◽  
Band Gap Engineering ◽  
High Defect Density ◽  
Transmission Electron ◽  
Different Temperatures

ABSTRACTA single crystalline Si1-xGex overlayer on insulator is realised by the implantation of germanium into a SIMOX (Separation by IMplantation of OXygen) substrate. Two SIMOX samples were implanted with 74Ge+ at elevated temperature (≈600°C), and subsequently annealed at different temperatures and anneal ambients. The microstructure, stoichiometry, and conductivity of the Si1-xGex over-layer were studied using transmission electron microscopy, Rutherford backscattering spectrometry/ion channelling and two-probe conductivity measurements. As a result of lattice reordering after final heat treatment, and despite high defect density observed in the XTEM microstructure, the measured conductivity of the over-layer is higher than of the starting SIMOX material. These results suggest a possibility of band-gap engineering by synthesis of Si1-xGex-on-insulator.

Dechannealing Study of Nanocrystalline Si:H Layers Produced by High Dose Hydrogen Irradiation of Silicon Crystals

1998 ◽  
Vol 536 ◽  
Author(s):  
V. P. Popov ◽  
A. K. Gutakovsky ◽  
I. V. Antonova ◽  
K. S. Zhuravlev ◽  
E. V. Spesivtsev ◽  
...  
Keyword(s):  
Electron Microscopy ◽  
Transmission Electron Microscopy ◽  
Rutherford Backscattering Spectrometry ◽  
Nanocrystalline Structure ◽  
Structural Defects ◽  
High Dose ◽  
Silicon Crystals ◽  
Strong Energy ◽  
Transmission Electron ◽  
Hydrogen Implantation

AbstractA study of Si:H layers formed by high dose hydrogen implantation (up to 3x107cm-2) using pulsed beams with mean currents up 40 mA/cm2 was carried out in the present work. The Rutherford backscattering spectrometry (RBS), channeling of He ions, and transmission electron microscopy (TEM) were used to study the implanted silicon, and to identify the structural defects (a-Si islands and nanocrystallites). Implantation regimes used in this work lead to creation of the layers, which contain hydrogen concentrations higher than 15 at.% as well as the high defect concentrations. As a result, the nano- and microcavities that are created in the silicon fill with hydrogen. Annealing of this silicon removes the radiation defects and leads to a nanocrystalline structure of implanted layer. A strong energy dependence of dechanneling, connected with formation of quasi nanocrystallites, which have mutual small angle disorientation (<1.50), was found after moderate annealing in the range 200-500°C. The nanocrystalline regions are in the range of 2-4 nm were estimated on the basis of the suggested dechanneling model and transmission electron microscopy (TEM) measurements. Correlation between spectroscopic ellipsometry, visible photoluminescence, and sizes of nanocrystallites in hydrogenated nc-Si:H is observed.

The orientation relationships of nanobelt-like Si2Hf precipitates in an Al–Si–Mg–Hf alloy

2016 ◽  
Vol 49 (4) ◽  
pp. 1223-1230 ◽  
Author(s):  
Xueli Wang ◽  
Huilan Huang ◽  
Xinfu Gu ◽  
Yanjun Li ◽  
Zhihong Jia ◽  
...  
Keyword(s):  
Electron Microscopy ◽  
Heat Treatment ◽  
Coincident Site Lattice ◽  
Orthorhombic Structure ◽  
Orientation Relationships ◽  
Lattice Distribution ◽  
Site Lattice ◽  
Transmission Electron ◽  
Habit Planes ◽  
Al Matrix

The orientation relationships (ORs) between the Al matrix and Si2Hf precipitates with an orthorhombic structure in an Al–Si–Mg–Hf alloy after heat treatment at 833 K for 20 h were investigated by transmission electron microscopy and electron diffraction. Four ORs are identified as (100)Al||(010)p, (0\overline {1}1)Al||(101)pand [011]Al||[\overline {1}01]p; (11\overline {1})Al||(010)pand [011]Al||[\overline {1}01]p; (12\overline {1})Al||(010)p, (101)Al||(100)pand [1\overline {11}]Al||[001]p; (\overline {11}1)Al||(010)pand [112]Al||[\overline {1}01]p. The habit planes of these four ORs are rationalized by the fraction of good atomic matching sites at the interface. In addition, the formation of Si2Hf precipitates with a nanobelt-like morphology is interpreted on the basis of the near-coincident site lattice distribution.

Study of Corrosion Behavior of Conventional and Nanostructured WC-Co HVOF Sprayed Coats

2010 ◽  
Vol 64 ◽  
pp. 13-18 ◽  
Author(s):  
Shahin Khameneh Asl ◽  
Mohammad Reza Saghi Beyragh ◽  
Mahdi Ghassemi Kakroudi
Keyword(s):  
Electron Microscopy ◽  
Heat Treatment ◽  
Corrosion Resistance ◽  
Electrochemical Impedance ◽  
Heat Treating ◽  
Crystalline Phases ◽  
Chemical Test ◽  
Transmission Electron ◽  
Hvof Spray ◽  
Wear And Corrosion Resistance

Interest in nanomaterials has increased in recent years. This is due to the potential of size reduction to nanometric scale to provide properties of materials such as hardness, toughness, wear, and corrosion resistance. The current study is focused on WC-Co cermet coats, materials that are extensively used in applications requiring wear resistance. In this work, WC-17Co powder was thermally sprayed onto mild steel using High Velocity Oxy Fuel (HVOF) spray technique. The nanostructured specimen was produced from sprayed sample by heat-treating at 1100°C in a vacuum chamber. Their structures were studied by using X-ray diffraction (XRD), scanning electron microscopy (SEM), and transmission electron microscopy (TEM). Polarization and electrochemical impedance spectroscopy (EIS) tests were performed on the both types of coated samples in 3.5% NaCl solution. The amorphous phase in WC-17Co coating was transformed to crystalline phases by heat treatment at high temperatures. The heat treatment of these coatings at high temperature also resulted in partially dissolution of WC particles and formation of new crystalline phases. Generation of these phases produced the nanostructured coating with better mechanical properties. Comparative electro chemical test results showed that, the heat treatment could improve corrosion resistance of the nanostructured WC-17Co coat than the as sprayed coats.

Deposition of nitrides and oxides of aluminum and titanium by pulse laser irradiation

1992 ◽  
Vol 7 (3) ◽  
pp. 725-733 ◽  
Author(s):  
S.R. Nishitani ◽  
S. Yoshimura ◽  
H. Kawata ◽  
M. Yamaguchi
Keyword(s):  
Electron Microscopy ◽  
Laser Irradiation ◽  
Pulse Laser ◽  
Rutherford Backscattering Spectrometry ◽  
Metal Vapor ◽  
Pulse Laser Irradiation ◽  
X Ray ◽  
Transmission Electron ◽  
Ambient Gas ◽  
Scanning Electron

Deposits of nitrides and oxides of Al and Ti have been produced by laser irradiation of Al and Ti targets in air, N2, and NH3 + N2 gases. Microstructure and constituent phases in these deposits have been examined by scanning electron microscopy (SEM), transmission electron microscopy (TEM), and x-ray diffractometry (XRD). The distribution of metalloid elements has been investigated by Rutherford backscattering spectrometry (RBS). On the basis of the results of these examinations, the nitride and oxide deposits have been shown to be formed by reactions between ambient gas and metal-melt or metal-vapor which take place during pulse laser irradiation.

scholarly journals Characterization of Gaas/Si/GaAs Heterointerfaces

1989 ◽  
Vol 148 ◽  
Author(s):  
Zuzanna Liliental-Weber ◽  
Raymond P. Mariella
Keyword(s):  
Electron Microscopy ◽  
Transmission Electron Microscopy ◽  
Low Temperature ◽  
Defect Density ◽  
Si Substrate ◽  
Reverse Polarity ◽  
Si Substrates ◽  
Transmission Electron ◽  
Metal Semiconductor Metal

ABSTRACTTransmission electron microscopy of GaAs grown on Si for metal-semiconductor-metal photodetectors is presented in this paper. Two kinds of samples are compared: GaAs grown on a 15 Å Si epilayer grown on GaAs, and GaAs grown at low temperature (300°C) on Si substrates. It is shown that the GaAs epitaxial layer grown on thin Si layer has reverse polarity to the substrate (antiphase relation). Higher defect density is observed for GaAs grown on Si substrate. This higher defect density correlates with an increased device speed, but with reduced sensitivity.

Microstructural evolution of dense and porous pyroelectric Pb1−xCaxTiO3 thin films

1999 ◽  
Vol 14 (5) ◽  
pp. 2012-2022 ◽  
Author(s):  
Andreas Seifert ◽  
Laurent Sagalowicz ◽  
Paul Muralt ◽  
Nava Setter
Keyword(s):  
Electron Microscopy ◽  
Thin Films ◽  
Microstructural Evolution ◽  
Rutherford Backscattering Spectrometry ◽  
X Ray Diffraction ◽  
Porous Films ◽  
Transmission Electron ◽  
Ca Substitution ◽  
High Figure ◽  
Low Permittivity

Pb1−xCaxTiO3 thin films with x = 0−0.3 for pyroelectric applications were deposited on platinized silicon wafers by chemical solution processing. Ca-substitution for Pb in PbTiO3 results in a reduced c/a ratio of the unit cell, which, in turn, leads to better pyroelectric properties. Control of nucleation and growth during rapid thermal annealing to 650 °C allowed the formation of either highly porous or dense (111) oriented films. The inclusion of pores creates a matrix-void composite with the low permittivity desired for pyroelectric applications, resulting in a high figure of merit. The growth mechanisms for the microstructural evolution of both dense and porous films were analyzed by x-ray diffraction, transmission electron microscopy, scanning electron microscopy, and Rutherford backscattering spectrometry and allowed establishment of microstructure/property relationships.

Microstructural Studies of High Coercivity Nd15Fe77B8 Sintered Magnets

1987 ◽  
Vol 96 ◽  
Author(s):  
M. H. Ghandehari ◽  
J. Fidler
Keyword(s):  
Electron Microscopy ◽  
Heat Treatment ◽  
Transmission Electron Microscopy ◽  
Grain Boundary ◽  
Electron Microprobe ◽  
Boundary Phase ◽  
High Coercivity ◽  
Transmission Electron ◽  
Microstructural Studies ◽  
Domain Reversal

ABSTRACTMicrostructures of Nd15−xDyxFe77B8 prepared by alloying with Dy, and by using Dy2O3 as a sinl'ken adidive, have been determined using electron microprobe and transmission electron microscopy. The results have shown a higher Dy concentration near the grain boundaries of the 2–14–1 phase for magnets doped with Dy2O 3, as compared to the Dy-alloyed magnets. A two-step post sintering heat treatment was also studied for the two systems. The resultant concentration gradient of Dy in the 2–14–1 phase of the oxide-doped magnets is explained by the reaction of Dy2O3 with the Nd-rich grain boundary phase and its slow diffusion into thg 4–14–1 phase. Increased Dy concentration near the grain boundary is more effective in improving the coercivity, as domain reversal nucleation originates at or near this region.

The effect of grain size on microstructure and stress relaxation in polycrystalline Y1Ba2Cu3O7−δ

1989 ◽  
Vol 4 (2) ◽  
pp. 248-256 ◽  
Author(s):  
T. M. Shaw ◽  
S. L. Shinde ◽  
D. Dimos ◽  
R. F. Cook ◽  
P. R. Duncombe ◽  
...  
Keyword(s):  
Electron Microscopy ◽  
Heat Treatment ◽  
Transmission Electron Microscopy ◽  
Grain Size ◽  
Stress Relaxation ◽  
Optical Microscopy ◽  
Slow Cooling ◽  
Hierarchical Arrangement ◽  
Transmission Electron ◽  
Processing Variables

We have used transmission electron microscopy and optical microscopy to examine the effect that grain size and heat treatment have on twinning and microcracking in polycrystalline Y1Ba2Cu3O7−δ. It is shown that isothermal oxygenation heat treatments produce twin structures consisting of parallel twins, with a characteristic spacing that increases with increasing grain size. Slow cooling through the temperature range where the orthorhombic-to-tetragonal transformation induces twinning, however, produces a structure consisting of a hierarchical arrangement of intersecting twins, the scale of which appears to be independent of grain size. It is also shown that the microcracking induced by anisotropic changes in grain dimensions on cooling or during oxygenation can be suppressed if the grain size of the material is kept below about 1 μm. The results are examined in the light of current models for transformation twinning and microcracking and the models used to access the effect other processing variables such as oxygen content, doping or heat treatment may have on the microstructure of Y1Ba2Cu3O7−δ.

Dynamic Compaction of Al Alloys

1983 ◽  
Vol 28 ◽  
Author(s):  
J.W. Sears ◽  
B.C. Muddle ◽  
H.L. Fraser
Keyword(s):  
Electron Microscopy ◽  
Heat Treatment ◽  
Transmission Electron Microscopy ◽  
Al Alloys ◽  
Dynamic Compaction ◽  
Al Alloy ◽  
Analytical Transmission Electron Microscopy ◽  
Projectile Velocity ◽  
Transmission Electron

ABSTRACTPowders of Al alloy 7091 have been consolidated by means of dynamic compaction. The dependence of density and hardness on projectile velocity has been determined. The resulting as-compacted material has been characterized using analytical transmission electron microscopy and evidence of interparticle melting observed. The microstructural responseof the compacted material to heat treatment at 523 and 723°K has been investigated.

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