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.

Imaging micro-twin distributions in as-grown CVD diamond films with TEM

1992 ◽  
Vol 50 (1) ◽  
pp. 336-337
Author(s):  
Z.L. Wang ◽  
L.L. Horton ◽  
R.E. Clausing ◽  
L. Heatherly ◽  
J. Bentley
Keyword(s):  
Diamond Films ◽  
Chemical Vapor ◽  
Cvd Diamond ◽  
Dark Field ◽  
Specimen Preparation ◽  
Preparation Technique ◽  
Bright Field ◽  
Fracture Specimen ◽  
Transmission Electron ◽  
Conventional Transmission Electron Microscope

Fractured edges of diamond films grown by chemical vapor deposition (CVD) have been examined directly in a conventional transmission electron microscope (TEM) without thinning, An important advantage of the fracture specimen preparation technique is that the microstructures in the diamond grains at the growth face can be characterized directly by bright-field (BF) and dark-field (DF) TEM imaging and diffraction. Additionally, the topography of the same region can be directly determined from secondary electron (SE) images available in the same TEM.

Fabrication and Characterization of NiO Bicrystals

1994 ◽  
Vol 357 ◽  
Author(s):  
Yong-Chae Chung ◽  
Bernhardt J. Wuensch
Keyword(s):  
Lattice Mismatch ◽  
Chemical Vapor ◽  
Growth Direction ◽  
Atomic Scale ◽  
Chemical Vapor Transport ◽  
Growth Surface ◽  
Free Standing ◽  
Transmission Electron ◽  
Tilt Boundaries

AbstractFabrication of NiO bicrystals having Σ5 (310) and Σ13 (510) coincidence-site tilt boundaries was successfully carried out by a CVT (Chemical Vapor Transport) method. The CVT method was a very advantageous way to grow ultra pure crystals since it preferentially transported NiO from the source pellet to the substrate by reaction with a HCl carrying gas. Single crystal MgO was used as a substrate for epitaxial growth of NiO as the readily available MgO crystals have only a 1% lattice mismatch with NiO. Moreover, MgO is soluble in acids while NiO is not. This permitted removal of the substrate crystal after growth to provide a free-standing NiO crystal. Using two single crystals of MgO with the desired tilt orientation as a substrate, NiO bicrystals were fabricated at growth rates greater than 100 μm/hour at 1,400K using 250 torr of HCI(g) as a carrying agent. The purity of the epitaxial NiO crystals was determined by mass spectrometry and neutron activation analysis. The grain boundary in the bicrystals is exactly perpendicular to the (100) growth surface. Highly-reflective facets along the growth direction suggest high mechanical quality. High-resolution transmission electron microscopy of the Σ13 boundary revealed structure at the atomic scale that provided no evidence for segregated phases.

Enhancement of Contrast in the CEM and STEM Using Bumpy Specimens and Employing the “Dappled Field” Mode of Operation

1974 ◽  
Vol 32 ◽  
pp. 552-553 ◽  
Author(s):  
L. Gandolfi ◽  
J. Reiffel
Keyword(s):  
Operating Mode ◽  
Scanning Transmission Electron Microscope ◽  
Dark Field ◽  
Specimen Preparation ◽  
Field Mode ◽  
Preparation Methods ◽  
Scanning Transmission Electron ◽  
Transmission Electron ◽  
Mode Of Operation ◽  
Scanning Transmission

Calculations have been performed on the contrast obtainable, using the Scanning Transmission Electron Microscope, in the observation of thick specimens. Recent research indicates a revival of an earlier interest in the observation of thin specimens with the view of comparing the attainable contrast using both types of specimens.Potential for biological applications of scanning transmission electron microscopy has led to a proliferation of the literature concerning specimen preparation methods and the controversy over “to stain or not to stain” in combination with the use of the dark field operating mode and the same choice of technique using bright field mode of operation has not yet been resolved.

TEM evaluation of graded SixGe1-x heterolayers

1991 ◽  
Vol 49 ◽  
pp. 894-895
Author(s):  
N. David Theodore ◽  
Mamoru Tomozane ◽  
Ming Liaw
Keyword(s):  
Heterojunction Bipolar Transistors ◽  
Gas Flow ◽  
Field Effect Transistors ◽  
Chemical Vapor ◽  
Dark Field ◽  
Bipolar Transistors ◽  
Structural Quality ◽  
Weak Beam ◽  
Transmission Electron ◽  
And Behavior

There is extensive interest in SiGe for use in heterojunction bipolar transistors. SiGe/Si superlattices are also of interest because of their potential for use in infrared detectors and field-effect transistors. The processing required for these materials is quite compatible with existing silicon technology. However, before SiGe can be used extensively for devices, there is a need to understand and then control the origin and behavior of defects in the materials. The present study was aimed at investigating the structural quality of, and the behavior of defects in, graded SiGe layers grown by chemical vapor deposition (CVD).The structures investigated in this study consisted of Si1-xGex[x=0.16]/Si1-xGex[x= 0.14, 0.13, 0.12, 0.10, 0.09, 0.07, 0.05, 0.04, 0.005, 0]/epi-Si/substrate heterolayers grown by CVD. The Si1-xGex layers were isochronally grown [t = 0.4 minutes per layer], with gas-flow rates being adjusted to control composition. Cross-section TEM specimens were prepared in the 110 geometry. These were then analyzed using two-beam bright-field, dark-field and weak-beam images. A JEOL JEM 200CX transmission electron microscope was used, operating at 200 kV.

Transmission Electron Microscopy (TEM) Specimen Preparation Technique using Focused Ion Beam (FIB): Application to Material Characterization of Chemical Vapor Deposition of Tungsten (W) and Tungsten Silicides (WSix)

1997 ◽  
Author(s):  
K. Doong ◽  
J.-M. Fu ◽  
Y.-C. Huang
Keyword(s):  
Electron Microscopy ◽  
Transmission Electron Microscopy ◽  
Chemical Vapor Deposition ◽  
Vapor Deposition ◽  
Focused Ion Beam ◽  
Ion Beam ◽  
Chemical Vapor ◽  
Specimen Preparation ◽  
Preparation Technique ◽  
Transmission Electron

Abstract The specimen preparation technique using focused ion beam (FIB) to generate cross-sectional transmission electron microscopy (XTEM) samples of chemical vapor deposition (CVD) of Tungsten-plug (W-plug) and Tungsten Silicides (WSix) was studied. Using the combination method including two axes tilting[l], gas enhanced focused ion beam milling[2] and sacrificial metal coating on both sides of electron transmission membrane[3], it was possible to prepare a sample with minimal thickness (less than 1000 A) to get high spatial resolution in TEM observation. Based on this novel thinning technique, some applications such as XTEM observation of W-plug with different aspect ratio (I - 6), and the grain structure of CVD W-plug and CVD WSix were done. Also the problems and artifacts of XTEM sample preparation of high Z-factor material such as CVD W-plug and CVD WSix were given and the ways to avoid or minimize them were suggested.

Control of Morphology and Growth Direction of Gallium Nitride Nanostructures

2003 ◽  
Vol 789 ◽  
Author(s):  
Seung Yong Bae ◽  
Hee Won Seo ◽  
Jeunghee Park
Keyword(s):  
Electron Microscopy ◽  
Gallium Nitride ◽  
Large Scale ◽  
Chemical Vapor ◽  
Growth Direction ◽  
Chemical Vapor Deposition Method ◽  
X Ray Diffraction ◽  
Oxide Mixture ◽  
Temperature Range ◽  
Transmission Electron

ABSTRACTVarious shaped single-crystalline gallium nitride (GaN) nanostructures were produced by chemical vapor deposition method in the temperature range of 900–1200 °C. Scanning electron microscopy, transmission electron microscopy, electron diffraction, x-ray diffraction, electron energy loss spectroscopy, Raman spectroscopy, and photoluminescence were used to investigate the structural and optical properties of the GaN nanostructures. We controlled the GaN nanostructures by the catalyst and temperature. The cylindrical and triangular shaped nanowires were synthesized using iron and gold nanoparticles as catalysts, respectively, in the temperature range of 900 – 1000 °C. We synthesized the nanobelts, nanosaws, and porous nanowires using gallium source/ boron oxide mixture. When the temperature of source was 1100 °C, the nanobelts having a triangle tip were grown. At the temperature higher up to 1200 °C the nanosaws and porous nanowires were formed with a large scale. The cylindrical nanowires have random growth direction, while the triangular nanowires have uniform growth direction [010]. The growth direction of the nanobelts is perpendicular to the [010]. Interestingly, the nanosaws and porous nanowires exhibit the same growth direction [011]. The shift of Raman, XRD, and PL bands from those of bulk was correlated with the strains of the GaN nanostructures.

Structure And Morphology Of Carbon Nanofibers Synthesized On Cu Nanopowders

2016 ◽  
Vol 11 (3) ◽  
pp. 62-71
Author(s):  
Gulmira Partizan ◽  
Batyr Mansurov ◽  
Botagoz Medyanova ◽  
Аizhan Koshanova ◽  
Madina Mansurova ◽  
...  
Keyword(s):  
Carbon Nanofibers ◽  
Chemical Vapor ◽  
Temperature Growth ◽  
Copper Clusters ◽  
Transmission Electron ◽  
Amorphous Nature ◽  
Diffraction Patterns ◽  
Stable Growth ◽  
Different Diameters ◽  
Copper Nanopowders

This article presents the results of experiments on the synthesis of carbon nanofibers by thermal chemical vapor deposition using copper nanopowders obtained by electric explosion of wire as catalysts. Stable growth of carbon nanofibers was carried out at temperatures significantly lower than normally used. The process parameters that are optimal for low-temperature growth of carbon nanofibers have been identified during the performed experiments. The synthesized samples have different diameters and morphology (from spiral to direct). Copper clusters are both at the ends and inside the fibers. The results of IR spectroscopy indicate that the structure of the obtained carbon nanofibers is polymeric. X-ray analysis revealed the presence of a halo on the diffraction patterns at small values of the angle 2θ, which proves that the grown structures have an amorphous nature. There are no groups that are responsible for long-range order in all Raman spectra. Studies by transmission electron microscopy showed that nanostructures do not have an internal channel and nanofibers are solid.

Direct Synthesis of Silicon Nanowires using Silane and Molten Gallium

2002 ◽  
Vol 737 ◽  
Author(s):  
Shashank Sharma ◽  
Mahendra K. Sunkara ◽  
Elizabeth C. Dickey
Keyword(s):  
Silicon Nanowires ◽  
Crystalline Silicon ◽  
Direct Synthesis ◽  
Growth Direction ◽  
Single Crystalline ◽  
Gas Phase Chemistry ◽  
Transmission Electron ◽  
Phase Chemistry ◽  
First Time ◽  
Low Solubility

ABSTRACTWe report for the first time, bulk synthesis of single crystalline silicon nanowires using molten gallium pools and an activated vapor phase containing silane. The resulting silicon nanowires were single crystalline with <100> growth direction. Nanowires contained an unexpectedly thin, non-uniform oxide sheath determined using high-resolution Transmission Electron Microscopy (TEM). Nanowires were tens of nanometers in diameter and tens to hundreds of microns long. The use of activated gas phase chemistry containing solute of interest over molten metal pools of low-solubility eutectics such as gallium offer a viable route to generate nanowire systems containing abrupt compositional hetero-interfaces.

Characterization of Inversion Domains in GaN by Electric Force Microscopy in Conjunction with Transmission Electron Microscopy and Wet Chemical Etching

2001 ◽  
Vol 680 ◽  
Author(s):  
F. Yun ◽  
P. Visconti ◽  
K. M. Jones ◽  
A. A. Baski ◽  
H. Morkoç ◽  
...  
Keyword(s):  
Electron Microscopy ◽  
Transmission Electron Microscopy ◽  
Control Sample ◽  
Chemical Vapor ◽  
Dark Field ◽  
Electric Force ◽  
Contact Potential ◽  
Force Microscopy ◽  
Transmission Electron ◽  
Electric Force Microscopy

ABSTRACTInversion domains (IDs) in III-nitride semiconductors degrade the performance of such devices, and so their identification and elimination is critical.An inversion domain on a Ga- polarity samples appears as an N-polarity domain, which has a polarization reversed with respect to the rest of the surface and therefore has a different surface potential. Surface-contact-potential electric force microscopy (SCP-EFM) is an extension of atomic force microscopy (AFM) that allows imaging of the surface electrostatic potential. Previously, we established the particular mode of operation necessary to identify inversion domains on III-nitrides using a control sample. We have now studied inversion domains in GaN films grown by metalorganic chemical vapor deposition (MOCVD) and molecular beam epitaxy (MBE). The existence of inversion domains was also verified by transmission electron microscopy (TEM) using multiple dark field imaging. In MOCVD grown GaN, we found predominant Ga-polarity with very low density of IDs, while in the MBE GaN, a mix polarity feature was identified.

A Study of the Origin of Band-A Emission in Homoepitaxial Diamond Thin Films

1999 ◽  
Vol 588 ◽  
Author(s):  
Daisuke Takeuchi ◽  
Hideyuki Watanabe ◽  
Sadanori Yamanaka ◽  
Hideyo Okushi ◽  
Koji Kajimura ◽  
...  
Keyword(s):  
Electron Microscopy ◽  
Transmission Electron Microscopy ◽  
High Resolution ◽  
Grain Boundaries ◽  
Microwave Plasma ◽  
Diamond Films ◽  
Chemical Vapor ◽  
Plasma Chemical Vapor Deposition ◽  
Transmission Electron ◽  
Excitonic Emission

AbstractThe band-A emission (around 2.8 eV) observed in high quality (device-grade) homoepitaxial diamond films grown by microwave-plasma chemical vapor deposition (CVD) was studied by means of scanning cathodoluminescence spectroscopy and high-resolution transmission electron microscopy. Recent progress in our study on homoepitaxial diamond films was obtained through the low CH4/H2 conditions by CVD. These showed atomically flat surfaces and the excitonic emission at room temperature, while the band-A emission (2.95 eV) decreased. Using these samples, we found that the band-A emission only appeared at unepitaxial crystallites (UC) sites, while other flat surface parts still showed the excitonic emission. High-resolution transmission electron microscopy revealed that there were grain boundaries which contained π-bonds in UC. This indicates that one of the origin of the band-A emission in diamond films is attributed to π bonds of grain boundaries.

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