Temperature Dependent Structural Evolution of Graphene Layers on 4H-SiC(0001)

2011 ◽  
Vol 679-680 ◽  
pp. 797-800 ◽  
Author(s):  
Sushant Sonde ◽  
Carmelo Vecchio ◽  
Filippo Giannazzo ◽  
Corrado Bongiorno ◽  
Salvatore di Franco ◽  
...  
Keyword(s):  
Electron Microscopy ◽  
Structural Evolution ◽  
Morphological Transformation ◽  
Temperature Dependent ◽  
Microscopy Imaging ◽  
Graphene Layers ◽  
Force Microscopy ◽  
Atomic Force ◽  
Transmission Electron ◽  
Mode Atomic Force Microscopy

In this study we examined the structural evolution of graphene grown on 8° off-axis 4H-SiC(0001) substrates at temperatures from 1600°C to 1700°C in Ar ambient. Morphological transformation of SiC substrate after annealing was examined by Tapping Mode Atomic Force Microscopy. Moreover, by etching-out graphene layers from graphitized SiC substrates in selective trenches we determined the number of graphene layers. Numbers of graphene layers were then independently confirmed by Transmission Electron Microscopy imaging.

Investigation of the Morphology of Recombinant Von Willebrand Factor by Two High-Resolution Microscopic Techniques

Blood ◽  
2010 ◽  
Vol 116 (21) ◽  
pp. 1409-1409
Author(s):  
Hanspeter Rottensteiner ◽  
Birgit K Seyfried ◽  
Gernot Friedbacher ◽  
Guenter Allmaier ◽  
Nicola Ilk ◽  
...  
Keyword(s):  
Electron Microscopy ◽  
Transmission Electron Microscopy ◽  
Life Sciences ◽  
Force Microscopy ◽  
Atomic Force ◽  
University Of Technology ◽  
Transmission Electron ◽  
Von Willebrand ◽  
Willebrand Factor ◽  
Mode Atomic Force Microscopy

Abstract Abstract 1409 Von Willebrand factor (VWF) is the largest known glycoprotein circulating in human blood plasma and is composed of a series of multimers with molecular weights ranging from 600 to 20,000 kDa or even more. In this study, we investigated the morphology of recombinant VWF (rVWF) and compared it to that of plasma-derived VWF (pdVWF) by tapping mode atomic force microscopy and transmission electron microscopy. Tapping mode atomic force microscopy showed that both rVWF and pdVWF contain globular and stretched domains. Mean chain lengths of the filaments and diameters of the core globular domains were determined and analyzed on a statistical basis. About 70% of the rVWF and pdVWF molecules were 100–300 nm long. The portion of very long molecules (>300 nm) was only slightly greater in rVWF than in pdVWF (20% versus 18%). The diameters of the globular core structures were in the range of 12 to 30 nm for both types of VWF. Inspection of a purified rVWF dimer revealed a similar range for the globular domain (14-32 nm). Upon exposure to high shear stress, a dramatic conformational change was observed for rVWF, just as has been reported for pdVWF. Investigation of negatively stained preparations of rVWF by transmission electron microscopy showed a highly organized structure. The heterogeneity in size observed was as expected for a polymeric VWF that consists of a mixture of multimers of varying sizes. The micrographs also revealed the presence of coiled and elongated structures. Analysis of pdVWF led to similar results, which were also in agreement with data from the literature. The results confirmed that the morphology of rVWF is similar to that observed for VWF purified from human normal plasma. Disclosures: Rottensteiner: Baxter Innovations GmbH: Employment. Seyfried:Baxter Innovations GmbH: Employment. Friedbacher:Vienna University of Technology: Consultancy. Allmaier:Vienna University of Technology: Consultancy. Ilk:University of Natural Resources and Applied Life Sciences: Consultancy. Sleytr:University of Natural Resources and Applied Life Sciences: Consultancy. Ehrlich:Baxter Innovations GmbH: Employment. Turecek:Baxter BioScience: Employment.

Preparation of a P(FcA-co-ANI)/graphene composite for application in supercapacitors

2016 ◽  
Vol 29 (5) ◽  
pp. 524-532 ◽  
Author(s):  
Yunlong Li ◽  
Yuying Zheng
Keyword(s):  
Electron Microscopy ◽  
Electrochemical Impedance ◽  
Proton Nuclear Magnetic Resonance ◽  
Diffusion Resistance ◽  
X Ray Diffraction ◽  
Graphene Layers ◽  
Force Microscopy ◽  
Atomic Force ◽  
Transmission Electron ◽  
Surface Morphologies

A conducting copolymer of 1,1′-ferrocenediacyl anilide and aniline (P(FcA-co-ANI)) was synthesized, which had a conjugated structure and ferrocene moieties in the main chain. The monomer and copolymer were characterized using proton nuclear magnetic resonance and Fourier-transform infrared (FTIR) spectroscopies. A P(FcA-co-ANI)/reduced graphene oxide (rGO) composite was synthesized by oxidation polymerization, using rGO as a substrate. The characteristic peaks of P(FcA-co-ANI) and rGO were observed in the FTIR spectrum of P(FcA-co-ANI)/rGO. The X-ray diffraction pattern of P(FcA-co-ANI)/rGO exhibited similar peaks to the pattern of P(FcA-co-ANI), except for the absence of the weak broad peak at 9.0° owing to rGO. The surface morphologies of the materials were characterized by atomic force microscopy, transmission electron microscopy and scanning electron microscopy. The interlayer distances of rGO and P(FcA-co-ANI)/rGO were 0.96 and 1.38 nm, respectively. The morphology of the copolymer was spherical, and it contained island structures covering the surface of the graphene layers. The electrochemical properties of the composite were measured by cyclic voltammetry, galvanostatic charge–discharge measurements and electrochemical impedance spectroscopy. The maximum specific capacitance of the composite was 722.5 F/g at 0.5 A/g. The diffusion resistance was very small, and the composites durability was sufficient for subjecting to prolonged oxidation and reduction.

Structural Characterization of Graphene Grown by Thermal Decomposition of Off-Axis 4H-SiC (0001)

2012 ◽  
Vol 711 ◽  
pp. 141-148 ◽  
Author(s):  
Filippo Giannazzo ◽  
Martin Rambach ◽  
Wielfried Lerch ◽  
Corrado Bongiorno ◽  
Salvatore di Franco ◽  
...  
Keyword(s):  
Electron Microscopy ◽  
Thermal Decomposition ◽  
Cross Section ◽  
Structural Characterization ◽  
Plan View ◽  
Graphene Layers ◽  
Force Microscopy ◽  
Atomic Force ◽  
Transmission Electron

We present a nanoscale morphological and structural characterization of few layers of graphene grown by thermal decomposition of off-axis 4H-SiC (0001). A comparison between transmission electron microscopy (TEM) in cross-section and in plan view allows to fully exploit the potentialities of TEM. Such a comparison was used to get information on the number of graphene layers as well as on the rotational order between the layers and with respect to the substrate. Some peculiar structures observed by TEM (wrinkles) could only be systematically measured by atomic force microscopy (AFM). In particular, the density and the height of the wrinkles in the few layers of graphene was investigated.

Defect-Engineered Graded GexSi1-x Buffers on Si (001) with Extreme Low Threading Dislocation Density

1995 ◽  
Vol 378 ◽  
Author(s):  
G. Kissinger ◽  
T. Morgenstern ◽  
G. Morgenstern ◽  
H. B. Erzgräber ◽  
H. Richter
Keyword(s):  
Electron Microscopy ◽  
Transmission Electron Microscopy ◽  
Atomic Force Microscopy ◽  
Dislocation Density ◽  
Threading Dislocation ◽  
Force Microscopy ◽  
Atomic Force ◽  
Transmission Electron ◽  
Dislocation Densities ◽  
Threading Dislocation Density

AbstractStepwise equilibrated graded GexSii-x (x≤0.2) buffers with threading dislocation densities between 102 and 103 cm−2 on the whole area of 4 inch silicon wafers were grown and studied by transmission electron microscopy, defect etching, atomic force microscopy and photoluminescence spectroscopy.

Effectiveness and Reliability of Metal Diffusion Barriers for Copper Interconnects

1995 ◽  
Vol 403 ◽  
Author(s):  
G. Bai ◽  
S. Wittenbrock ◽  
V. Ochoa ◽  
R. Villasol ◽  
C. Chiang ◽  
...  
Keyword(s):  
Electron Microscopy ◽  
Vapor Deposition ◽  
Physical Vapor Deposition ◽  
Chemical Vapor ◽  
Diffusion Barriers ◽  
Copper Interconnects ◽  
Time To Failure ◽  
Force Microscopy ◽  
Atomic Force ◽  
Transmission Electron

AbstractCu has two advantages over Al for sub-quarter micron interconnect application: (1) higher conductivity and (2) improved electromigration reliability. However, Cu diffuses quickly in SiO2and Si, and must be encapsulated. Polycrystalline films of Physical Vapor Deposition (PVD) Ta, W, Mo, TiN, and Metal-Organo Chemical Vapor Deposition (MOCVD) TiN and Ti-Si-N have been evaluated as Cu diffusion barriers using electrically biased-thermal-stressing tests. Barrier effectiveness of these thin films were correlated with their physical properties from Atomic Force Microscopy (AFM), Transmission Electron Microscopy (TEM), Secondary Electron Microscopy (SEM), and Auger Electron Spectroscopy (AES) analysis. The barrier failure is dominated by “micro-defects” in the barrier film that serve as easy pathways for Cu diffusion. An ideal barrier system should be free of such micro-defects (e.g., amorphous Ti-Si-N and annealed Ta). The median-time-to-failure (MTTF) of a Ta barrier (30 nm) has been measured at different bias electrical fields and stressing temperatures, and the extrapolated MTTF of such a barrier is > 100 year at an operating condition of 200C and 0.1 MV/cm.

Development of Ge Nanoparticles Embedded in GeO2 Matrix

2008 ◽  
Vol 8 (8) ◽  
pp. 4081-4085 ◽  
Author(s):  
Y. Batra ◽  
D. Kabiraj ◽  
D. Kanjilal
Keyword(s):  
Electron Microscopy ◽  
Annealing Temperature ◽  
Spectroscopic Studies ◽  
Electron Beam Evaporation ◽  
Granular Structure ◽  
Raman Analysis ◽  
Force Microscopy ◽  
Atomic Force ◽  
Transmission Electron ◽  
Ge Nanocrystals

Germanium (Ge) nanoparticles have attracted a lot of attention due to their excellent optical properties. In this paper, we report on the formation of Ge nanoparticles embedded in GeO2 matrix prepared by electron beam evaporation and subsequent annealing. Transmission electron microscopy (TEM) studies clearly indicate the formation of Ge nanocrystals in the films annealed at 500 °C. Fourier transform infrared (FTIR) spectroscopic studies are carried out to verify the evolution of the structure after annealingat each stage. Micro-Raman analysis also confirms the formation of Ge nanoparticles in the annealed films. Development of Ge nanoparticles is also established by photoluminescence (PL) analysis. Surface morphology study is carried out by atomic force microscopy (AFM). It shows the evolution of granular structure of the films with increasing annealing temperature.

scholarly journals Measuring the Autocorrelation Function of Nanoscale Three-Dimensional Density Distribution in Individual Cells Using Scanning Transmission Electron Microscopy, Atomic Force Microscopy, and a New Deconvolution Algorithm

2017 ◽  
Vol 23 (3) ◽  
pp. 661-667 ◽  
Author(s):  
Yue Li ◽  
Di Zhang ◽  
Ilker Capoglu ◽  
Karl A. Hujsak ◽  
Dhwanil Damania ◽  
...  
Keyword(s):  
Electron Microscopy ◽  
Density Distribution ◽  
Scanning Transmission Electron Microscopy ◽  
Mass Density ◽  
Three Dimensional ◽  
Force Microscopy ◽  
Statistical Measures ◽  
Atomic Force ◽  
Transmission Electron ◽  
Scanning Transmission

AbstractEssentially all biological processes are highly dependent on the nanoscale architecture of the cellular components where these processes take place. Statistical measures, such as the autocorrelation function (ACF) of the three-dimensional (3D) mass–density distribution, are widely used to characterize cellular nanostructure. However, conventional methods of reconstruction of the deterministic 3D mass–density distribution, from which these statistical measures can be calculated, have been inadequate for thick biological structures, such as whole cells, due to the conflict between the need for nanoscale resolution and its inverse relationship with thickness after conventional tomographic reconstruction. To tackle the problem, we have developed a robust method to calculate the ACF of the 3D mass–density distribution without tomography. Assuming the biological mass distribution is isotropic, our method allows for accurate statistical characterization of the 3D mass–density distribution by ACF with two data sets: a single projection image by scanning transmission electron microscopy and a thickness map by atomic force microscopy. Here we present validation of the ACF reconstruction algorithm, as well as its application to calculate the statistics of the 3D distribution of mass–density in a region containing the nucleus of an entire mammalian cell. This method may provide important insights into architectural changes that accompany cellular processes.

scholarly journals Spore Coat Architecture of Clostridium novyi NT Spores

2007 ◽  
Vol 189 (17) ◽  
pp. 6457-6468 ◽  
Author(s):  
Marco Plomp ◽  
J. Michael McCaffery ◽  
Ian Cheong ◽  
Xin Huang ◽  
Chetan Bettegowda ◽  
...  
Keyword(s):  
Electron Microscopy ◽  
Transmission Electron Microscopy ◽  
Anaerobic Bacterium ◽  
Amorphous Layer ◽  
Spore Coat ◽  
Experimental Animals ◽  
Force Microscopy ◽  
Atomic Force ◽  
Clostridium Novyi ◽  
Transmission Electron

ABSTRACT Spores of the anaerobic bacterium Clostridium novyi NT are able to germinate in and destroy hypoxic regions of tumors in experimental animals. Future progress in this area will benefit from a better understanding of the germination and outgrowth processes that are essential for the tumorilytic properties of these spores. Toward this end, we have used both transmission electron microscopy and atomic force microscopy to determine the structure of both dormant and germinating spores. We found that the spores are surrounded by an amorphous layer intertwined with honeycomb parasporal layers. Moreover, the spore coat layers had apparently self-assembled, and this assembly was likely to be governed by crystal growth principles. During germination and outgrowth, the honeycomb layers, as well as the underlying spore coat and undercoat layers, sequentially dissolved until the vegetative cell was released. In addition to their implications for understanding the biology of C. novyi NT, these studies document the presence of proteinaceous growth spirals in a biological organism.

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