scholarly journals Evaluation of the Thickness in Nanolayers Using the Transfer Matrix Method for Modeling the Spectral Reflectivity

2009 ◽  
Vol 2009 ◽  
pp. 1-4 ◽  
Author(s):  
Juan E. González-Ramírez ◽  
Juan Fuentes ◽  
Luis C. Hernández ◽  
Luís Hernández
Keyword(s):  
Transfer Matrix ◽  
Semiconductor Films ◽  
Experimental Room ◽  
Spectral Reflectivity ◽  
Present Procedure ◽  
Transmission Electron ◽  
Reflectivity Spectra ◽  
Gaas Films ◽  
Transparent Region ◽  
Microscopy Techniques

The reflectivity spectra have been traditionally used to determine the thicknesses in semiconductor films. However, thicknesses of nanofilms are not easy to evaluate because the interference fringes are not visible in the transparent region. In this paper, we present a computed method based on the transfer matrix (TM) which is used to match the calculated and experimental room temperature reflectivity spectra of the ZnTe/GaAs films and to determine its thickness film values afterwards. The TM method needs only to know refraction indices and absorption coefficients as a function of wavelength for the film and the substrate. The thickness nanofilms evaluated by our method are in agreement with the values measured by ellipsometry, Rutherford backscattering spectroscopy and transmission electron microscopy techniques. The present procedure extends the application of the standard spectral reflectance technique to determine semiconductor nanolayer thicknesses.

Nanoscale Structural and Chemical Segregation in Pt50Ru50 Electrocatalysts

2001 ◽  
Vol 7 (S2) ◽  
pp. 1112-1113
Author(s):  
Rhonda M. Stroud ◽  
Jeffrey W. Long ◽  
Karen E. Swider-Lyons ◽  
Debra R. Rolison
Keyword(s):  
Methanol Oxidation ◽  
Structural Heterogeneity ◽  
Oxidation Activity ◽  
Bimetallic Alloy ◽  
Transmission Electron ◽  
Chemical Segregation ◽  
High Fraction ◽  
Argon Mixture ◽  
Microscopy Techniques ◽  
Electron Energy Loss

To address how the chemical and structural heterogeneity of Pt50Ru50 nanoparticles affects methanol oxidation activity, we have employed an arsenal of transmission electron microscopy techniques (conventional bright field-imaging, selected area diffraction, atomic-resolution lattice imaging, electron-energy loss spectroscopy, and energy-dispersive x-ray spectroscopy) to characterize 2.5-nm particles in differing oxidation and hydration states. Our studies demonstrate that electrocatalysts containing a high fraction of Ru-rich hydrous oxide, as apposed to the anhydrous PtRu bimetallic alloy, have as much as 250x higher methanol oxidation activityThe nominally 2.5-nm Pt50Ru50 particles were studied in as-received, reduced and reoxidized forms. The reducing treatment consisted of 2 h at 100 °C in flowing 10% PL/argon mixture. For re-oxidation, the reduced particles were heated for 20 h at 100 °C in an H2O-saturated oxygen atmosphere. The particles were suspended in methanol, and pipetted onto holey-carboncoated Cu grids for TEM studies.

Orientation domains in the intermediate product Na3TiOF5during the synthesis of anatase TiO2nanosheets with exposed reactive {001} facets

2013 ◽  
Vol 46 (6) ◽  
pp. 1741-1748 ◽  
Author(s):  
Yi Xiong ◽  
Shuangfeng Jia ◽  
Jianbo Wang ◽  
Shang Peng ◽  
Lu Lu ◽  
...  
Keyword(s):  
Intermediate Product ◽  
Cubic Phase ◽  
Monoclinic Structure ◽  
Theory Analysis ◽  
Selected Area Electron Diffraction ◽  
Transmission Electron ◽  
Domain Boundaries ◽  
Coherent Domain ◽  
Microscopy Techniques ◽  
Orientation Domain

A powder of oxyfluorotitanate Na3TiOF5crystals is acquired as an intermediate product during the synthesis of anatase titanium dioxide (TiO2) nanosheets with a large percentage of exposed reactive {001} facets. By application of transmission electron microscopy techniques, mainly energy dispersive spectroscopy and selected-area electron diffraction, coherent domain variants of Na3TiOF5are shown to possess monoclinic structure with space groupP21/n. The occurrence of these orientation domain variants is attributed to the reduction of crystal symmetry as a result of the phase transition from the high-temperature cubic phase to the low-temperature monoclinic phase. Through a detailed group theory analysis, the orientation domains are shown to exhibit 12 variants and 11 domain boundaries, which can be categorized into three types of perpendicular twins and two types of antiparallel twins. This work may provide meaningful insight for understanding the growth mechanism of anatase TiO2with a high percentage of reactive facets.

scholarly journals Ultrastructure of the adrenal gland of paca (Cuniculus paca, Linnaeus, 1766) in captivity

2021 ◽  
Vol 15 (3) ◽  
pp. 203-208
Author(s):  
Sérgio Pinter Garcia Filho ◽  
Leandro Luis Martins ◽  
Paulo Fernandes Marcusso ◽  
Tais Harumi de Castro Sasahara ◽  
Márcia Rita Fernandes Machado
Keyword(s):  
Electron Microscopy ◽  
Adrenal Gland ◽  
Adrenal Glands ◽  
Comparative Anatomy ◽  
The Body ◽  
Cortical Region ◽  
Lateral Incision ◽  
Transmission Electron ◽  
In Captivity ◽  
Microscopy Techniques

Lowland paca (Cuniculus paca, Linnaeus, 1766) is a medium-sized rodent that belongs to the Brazilian fauna. Yet little information on its morphology is found in the specialized literature. Thus, the objective of the work was to study the morphology of the adrenal gland of paca by means of microscopic ultrastructure analysis. The adrenal gland secretes specialized substances in the body which promote biological functions of great importance and will provide valuable information to studies in comparative anatomy. Two (2) adult lowland pacas were used, male and female. Soon after death, the animals were positioned in the supine position; their abdominal cavities were opened by pre-retro umbilical and lateral incision followed by folding of the abdominal walls to expose the glands. The adrenal glands were removed; fragments were collected, fixed and prepared for ultrastructure observations using scanning electron microscopy and transmission electron microscopy techniques. It was observed that the adrenal glands of the paca have divisions as well as the limits of the cortical and medullary region, as well as the subdivisions of the glomerulosa, fasciculated and reticulated areas of the cortical region as in other rodents. An ultrastructure of cells and their components also showed a lot of similarity to that already demonstrated in different rodents.

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.

Stress Relaxation Behavior of GH4169 Alloy

2020 ◽  
Vol 1013 ◽  
pp. 52-58
Author(s):  
Xu Dong Lu ◽  
Song Yi Shi ◽  
Bo Wen ◽  
Ya Wei Zhang ◽  
Jin Hui Du
Keyword(s):  
Electron Microscopy ◽  
Transmission Electron Microscopy ◽  
Stress Relaxation ◽  
Initial Stress ◽  
Relaxation Behavior ◽  
Stress Relaxation Behavior ◽  
Transmission Electron ◽  
Microscopy Techniques ◽  
The Relationship ◽  
Gh4169 Alloy

The relaxation properties of GH4169 alloy were studied contrastively at temperatures ranging from 600 oC to 700 °C and initial stress ranging from 550 MPa to 850 MPa. The relationship between the microstructure and relaxation behavior was evaluated using transmission electron microscopy techniques. It was found that the relaxation limit and relaxation stability of the alloy decreased obviously with the increase of temperature. Further investigations show that the relaxation behavior is mainly depend on both precipitate characteristics and its interaction with dislocations. The alloy with higher strength lever has more excellent stress relaxation stability, because of the inhibition of a large number subgrains on dislocations motion.

The Starting Members of the Series Pr4n+2(C2)nBr5n+5 (n = 1, 2, 3)

2009 ◽  
Vol 64 (8) ◽  
pp. 922-928 ◽  
Author(s):  
Manuel Christian Schaloske ◽  
Hansjürgen Mattausch ◽  
Viola Duppel ◽  
Lorenz Kienle ◽  
Arndt Simon
Keyword(s):  
Electron Microscopy ◽  
Transmission Electron Microscopy ◽  
Single Crystals ◽  
Lattice Parameters ◽  
Space Group ◽  
X Ray ◽  
Transmission Electron ◽  
General Series ◽  
Microscopy Techniques

The compounds Pr6(C2)Br10, Pr10(C2)2Br15 and Pr14(C2)3Br20 were prepared from PrBr3 and the appropriate amounts of Pr and C and characterized by X-ray structure analyses of single crystals. All three compounds crystallize in space group P1 with lattice parameters a = 7.571(2), b = 9.004(2), c = 9.062(2) Å ,α = 108.57(3), β = 97.77(3), γ = 106.28(3)◦ for Pr6(C2)Br10; a = 9.098(2), b = 10.127(2), c = 10.965(2) A° , α = 70.38(3), β = 66.31(3), γ = 70.84(3)◦ for Pr10(C2)2Br15; a = 9.054(2), b = 10.935(2), c = 13.352(3) Å , α = 86.27(3), β = 72.57(3), γ = 66.88(3)◦ for Pr14(C2)3Br20. They are members of a general series Ln4n+2(C2)nBr5n+5 and isostructural with the corresponding iodides known for Ln = La, Ce, Pr. Pr6(C2)Br10 was further characterized via transmission electron microscopy techniques

The Creation and Annealing of Heavy Ion Damage in Silicon

1987 ◽  
Vol 93 ◽  
Author(s):  
L. M. Howe ◽  
M. H. Rainville
Keyword(s):  
Electron Microscopy ◽  
Transmission Electron Microscopy ◽  
Spatial Distribution ◽  
High Resolution ◽  
Heavy Ion ◽  
High Energy ◽  
Transmission Electron ◽  
Ion Damage ◽  
Deposited Energy ◽  
Microscopy Techniques

ABSTRACTHigh resolution transmission electron microscopy techniques have been used to obtain information on the contrast, spatial distribution, size and annealing behaviour of the damaged regions produced within individual collision cascades by heavy ion (As, Sb and Bi) bombardment (10–120 KeV) of silicon with 1.0 × 1011 – 6.0 × 1011 ions cm−2. The fraction of the theoretical cascade volume occupied by a heavily damaged region steadily increased as the average deposited energy density within the cascade increased. At high energy densities, the visible damage produced in the main cascade consisted of a single, isolated damaged region. With decreasing values of (i.e. increasing ion implant energies), there was an increasing tendency for multiple damaged regions to be produced within the main cascade.

scholarly journals Scanning Microscopy Techniques as an Assessment Tool of Materials and Interventions for the Protection of Built Cultural Heritage

Scanning ◽  
2019 ◽  
Vol 2019 ◽  
pp. 1-20 ◽  
Author(s):  
Antonia Moropoulou ◽  
Elisabetta Zendri ◽  
Pilar Ortiz ◽  
Ekaterini T. Delegou ◽  
Ioanna Ntoutsi ◽  
...  
Keyword(s):  
Electron Microscopy ◽  
Scanning Electron Microscopy ◽  
Assessment Tool ◽  
Scanning Microscopy ◽  
Spectroscopy Analysis ◽  
Built Heritage ◽  
Research Areas ◽  
Transmission Electron ◽  
Microscopy Techniques ◽  
Scanning Electron

Scanning microscopy techniques have emerged as powerful scientific tools for analysing materials of architectural or archaeological interest, since the commercialization of the first scanning electron microscopy instrumentation in the early 60s. This study is aimed at reviewing and highlighting the significance of several scanning microscopy techniques employed in the protection of built heritage. The diffusion of scanning electron microscopy with energy-dispersive X-ray spectroscopy analysis (SEM-EDX) is proven to be the widest among the available scanning microscopy techniques, while transmission electron microscopy (TEM) applications are steadily present in the field of built heritage protection. The building material characterization, the weathering mechanism investigation, and the development of compatible and performing conservation materials are some major research areas where the application of the aforementioned techniques is discussed. The range of techniques, along with aspects of instrumentation and sample preparation are, also, considered.

Role of Electron Microscopy in Semiconductor Electronic Defects Analysis

1985 ◽  
Vol 46 ◽  
Author(s):  
P. M. Petroff
Keyword(s):  
Electron Microscopy ◽  
Transmission Electron Microscopy ◽  
Transmission Electron ◽  
Semiconductor Electronic ◽  
Scanning Transmission ◽  
Electronic Defect ◽  
Defects Analysis ◽  
Microscopy Techniques ◽  
Electronic Defects

AbstractA review of the Transmission Electron Microscopy and Scanning Transmission Electron Microscopy techniques used for electronic defect identification is presented. The structural, chemical and STEM based spectroscopy methods for electronic defect analysis are discussed along with selected examples.

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