High-resolution transmission electron microscopy (HRTEM) observation of dislocation structures in AlN thin films

2008 ◽  
Vol 23 (8) ◽  
pp. 2188-2194 ◽  
Author(s):  
Yuki Tokumoto ◽  
Naoya Shibata ◽  
Teruyasu Mizoguchi ◽  
Masakazu Sugiyama ◽  
Yukihiro Shimogaki ◽  
...  
Keyword(s):  
Electron Microscopy ◽  
Transmission Electron Microscopy ◽  
High Resolution ◽  
Film Growth ◽  
Threading Dislocations ◽  
Organic Vapor ◽  
Transmission Electron ◽  
Hrtem Observation ◽  
Metal Organic ◽  
Edge Dislocations

The structure and configuration of threading dislocations (TDs) in AlN films grown on (0001) sapphire by metal–organic vapor phase epitaxy (MOVPE) were characterized by high-resolution transmission electron microscopy (HRTEM). It was found that the TDs formed in the films were mainly the perfect edge dislocations with the Burgers vector of b = ⅓〈11¯20〉. The majority of the edge TDs were not randomly formed but densely arranged in lines. The arrays of the edge TDs were mainly observed on the {11¯20} and {10¯10} planes. These two planes showed different configurations of TDs. TD arrays on both of these planes constituted low-angle boundaries. We suggest that these TDs are introduced to compensate for slight misorientations between the subgrains during the film growth.

Transmission Electron Microscopy Studies of 5-cycled Na Alanate with Ti Based Additive

2005 ◽  
Vol 884 ◽  
Author(s):  
Carmen M. Andrei ◽  
John C. Walmsley ◽  
Randi Holmestad ◽  
Gianluigi A. Botton ◽  
Sesha S. Srinivasan ◽  
...  
Keyword(s):  
Electron Microscopy ◽  
Transmission Electron Microscopy ◽  
High Resolution ◽  
Electron Diffraction ◽  
Hydrogen Storage Material ◽  
Hydrogen Diffusivity ◽  
Storage Material ◽  
X Ray ◽  
Transmission Electron ◽  
Edge Dislocations

AbstractTi doped NaAlH4 hydride is proposed as a reversible hydrogen storage material. In this work, the microstructure of NaAlH4 with 2% TiCl3 additive was studied after 5 hydrogen cycles using a combination of transmission electron microscopy (TEM) techniques including energy dispersive spectroscopy (EDS) X-ray analysis. Selected area diffraction and high-resolution (HR) imaging confirmed the presence of the NaH phase in the material. Electron diffraction was dominated by Al. HRTEM showed the presence of edge dislocations, which might influence the hydrogen diffusivity process in these materials.

Dislocations in SrTiO3 thin films grown on LaAlO3 substrates

2002 ◽  
Vol 17 (12) ◽  
pp. 3117-3126 ◽  
Author(s):  
Y. L. Qin ◽  
C. L. Jia ◽  
K. Urban ◽  
J. H. Hao ◽  
X. X. Xi
Keyword(s):  
Electron Microscopy ◽  
Thin Films ◽  
Transmission Electron Microscopy ◽  
High Resolution ◽  
Lattice Mismatch ◽  
Orthogonal Arrays ◽  
Threading Dislocations ◽  
Misfit Dislocations ◽  
Burgers Vector ◽  
Transmission Electron

The dislocation configurations in SrTiO3 thin films grown epitaxially on LaAlO3 (100) substrates were studied by conventional and high-resolution transmission electron microscopy. Misfit dislocations had, in most cases, a Burgers vector a〈100〉 and line directions of 〈100〉 These dislocations constitute orthogonal arrays of parallel dislocations at the interface, relieving the lattice mismatch between SrTiO3 and LaAlO3. Threading dislocations were found to be the major defects in the films. Two types of threading dislocations with the Burgers vectors a〈100〉?and a〈100〉?were identified. The relations of these threading dislocations with the misfit dislocations were investigated and are discussed in this paper.

Microstructure - Roughness Interelation in Ru/C and Ru/B4C X-RAY Multilayers

1992 ◽  
Vol 280 ◽  
Author(s):  
Tai D. Nguyen ◽  
Ronald Gronsky ◽  
Jeffrey B. Kortricht
Keyword(s):  
Electron Microscopy ◽  
Transmission Electron Microscopy ◽  
High Resolution ◽  
Diffuse Component ◽  
Interfacial Roughness ◽  
Cross Sectional ◽  
X Ray ◽  
Specular Scattering ◽  
Transmission Electron ◽  
Hrtem Observation

ABSTRACTX-ray specular and non-specular scattering, and high-resolution transmission electron microscopy (HRTEM) were performed to study the evolution of the microstructures and interfacial roughness in Ru/C and RU/B4C multilayers upon annealing. The microstructure of the approximately 1.4 nm thick Ru layers in the as-prepared 3.5 nm period multilayers is predominantly amorphous. The Ru layers in the Ru/B4C multilayer show RuB2nano-crystallites after annealing at 600°C for one hour, while those in the Ru/C multilayer crystallize to form hexagonal Ru crystallites. Cross-sectional HRTEM of the annealed Ru/C multilayer also shows agglomeration of the Ru layers. Non-specular measurements of the Ru/C multilayers indicate an enhanced uncorrelated roughness upon annealing. The diffuse component in the as-prepared and annealed RU/B4C multilayers shows insignificant changes. The increase in interfacial roughness in the Ru/C multilayer results from agglomeration of the Ru after annealing, consistent with HRTEM observation.

Study of the Origin of Misorientation in GaN Grown by Pendeo-Epitaxy

2002 ◽  
Vol 743 ◽  
Author(s):  
D. N. Zakharov ◽  
Z. Liliental-Weber ◽  
A. M. Roskowski ◽  
S. Einfeldt ◽  
R. F. Davis
Keyword(s):  
Electron Microscopy ◽  
Transmission Electron Microscopy ◽  
Dislocation Density ◽  
Growth Temperature ◽  
Threading Dislocations ◽  
Transmission Electron ◽  
Edge Dislocations ◽  
Seed Layers

ABSTRACTGrowth of pendeo-epitaxial (PE) layers introduces misorientation between the seed layers and the overgrown wing layers. The origin of this misorientation has been studied by Transmission Electron Microscopy (TEM) using a set of samples in which subsequent procedures utilized in PE were applied, i.e. growth of GaN template, stripe etching, annealing at the growth temperature of the PE layers and final PE growth. It was shown that etching of seed-stripes did not change the type of defects or their distribution. However, heating to the PE growth temperature drastically modified the surface and V-shaped pits were formed. The surface became smooth again after the PE growth took place. Overgrowth of the V-shaped pits resulted in formation of edge threading dislocations over a seed-stripe region with a dislocation density of 8.0×108 cm−2. Formation of new edge dislocations over the seed can have an influence on the misorientation between the PE grown regions.

HRTEM Observation of Precipitates in Mg-Gd-Zr and Mg-Y-Zr Alloys Aged at 423 K

2012 ◽  
Vol 706-709 ◽  
pp. 1205-1208
Author(s):  
Tokimasa Kawabata ◽  
Kenji Matsuda ◽  
Susumu Ikeno
Keyword(s):  
Electron Microscopy ◽  
Transmission Electron Microscopy ◽  
High Resolution ◽  
Early Stage ◽  
Magnesium Matrix ◽  
Transmission Electron ◽  
Hrtem Observation ◽  
Peak Aged ◽  
Zr Alloy ◽  
Zr Alloys

High resolution transmission electron microscopy (HRTEM) observation was performed to clarify the early stage of precipitation in Mg-Gd (-Zr) alloy and Mg-Y(-Zr) alloy aged at 423 K. At the early stage of agigng at 423 K, the intensity of the diffuse spots become higher at the 1/2 distance of 1100 or 2110 corresponding to magnesium matrix spots with aging time. Contrasts of mono layers on {100}Mgplanes, and the feature of D019type structure, precipitates with five layers corresponding the feature of (020)b'plane and b' phase co-existed and b' phase formed predominantly in the peak aged Mg-Gd (-Zr) alloy at 423 K, wheres in the peak aged Mg-Y(-Zr) alloy at 423 K, monolayer and precursor of precipitates with five layers corresponding the feature of (020)b'plane formed predominantly.

Edge dislocations in fibrous grunerite

1981 ◽  
Vol 44 (335) ◽  
pp. 287-291
Author(s):  
E. J. W. Whittaker ◽  
B. A. Cressey ◽  
J. L. Hutchison
Keyword(s):  
Electron Microscopy ◽  
Transmission Electron Microscopy ◽  
High Resolution ◽  
Cross Sections ◽  
The Other ◽  
Two Dimensional ◽  
Equal Frequency ◽  
Burgers Vector ◽  
Transmission Electron ◽  
Edge Dislocations

AbstractSections perpendicular to [001] of ion-thinned specimens of fibrous grunerite (amosite) have been examined by high-resolution transmission electron microscopy. In this orientation, two kinds of dislocation have been observed with about equal frequency. One lies on [001] and has a Burgers vector a. The other is on [001] and has a Burgers vector ½a+½b Interpretation of features associated with these dislocations has been assisted by the use of two-dimensional models of I-beam cross-sections which can be interlocked to simulate the possible modes of stacking.

Age-Hardening Behaviour and HRTEM Observation of Precipitates in Excess Mg Type Al-Mg-Si-Ag Alloy

2006 ◽  
Vol 519-521 ◽  
pp. 507-510 ◽  
Author(s):  
Azusa Furihata ◽  
Kenji Matsuda ◽  
Junya Nakamura ◽  
Susumu Ikeno ◽  
Yasuhiro Uetani
Keyword(s):  
Electron Microscopy ◽  
Transmission Electron Microscopy ◽  
High Resolution ◽  
Age Hardening ◽  
Transmission Electron ◽  
Hrtem Observation ◽  
Excess Mg

In this work, the age-hardening of Al- 1.0 mass% Mg2Si- 0.4 mass% Mg – 0.5 mass% Ag (ex.Mg-Ag alloy) alloy has been investigated. It showed increase of hardness and age-hardening response. Precipitates in this alloy aged at 523 K have been observed by high resolution transmission electron microscopy (HRTEM) and classified into five types based on characteristics in their HRTEM images.

Transmission electron microscopy study of epitaxial InN thin films grown on c-plane sapphire

2006 ◽  
Vol 21 (7) ◽  
pp. 1693-1699 ◽  
Author(s):  
C.J. Lu ◽  
X.F. Duan ◽  
Hai Lu ◽  
William J. Schaff
Keyword(s):  
Electron Microscopy ◽  
Thin Films ◽  
Transmission Electron Microscopy ◽  
Film Growth ◽  
Microscopy Study ◽  
Electron Microscopy Study ◽  
Threading Dislocations ◽  
Transmission Electron Microscopy Study ◽  
Transmission Electron ◽  
Gan Buffer Layer

High-quality epitaxial InN thin films grown on (0001) sapphire with GaN buffer were characterized using transmission electron microscopy. It was found that the GaN buffer layer exhibits the (0001) Ga polarity and the InN film has In-terminated polarity. At the InN/GaN interface, there exists a high density of misfit dislocation (MD) array. Perfect edge threading dislocations (TDs) with (1/3)〈1120〉 Burgers vectors are predominant defects that penetrate the GaN and InN layers. Pure screw and mixed TDs were also observed. Overall, the TD density decreases during film growth due to annihilation and fusion. The TD density in GaN is as high as ∼1.5 × 1011 cm−2, and it drops rapidly to ∼2.2 × 1010 cm−2 in InN films. Most half-loops in GaN are connected with MD segments at the InN/GaN interface to form loops, while some TD segments threaded the interface. Half-loops were also generated during the initial stages of InN growth.

A High Resolution Study of G.P. Zones in Aluminum - 4.2 at % Silver

1982 ◽  
Vol 40 ◽  
pp. 722-723 ◽  
Author(s):  
R. Gronsky
Keyword(s):  
Electron Microscopy ◽  
Transmission Electron Microscopy ◽  
High Resolution ◽  
Computer Simulations ◽  
Structural Characteristics ◽  
X Ray Diffraction ◽  
X Ray ◽  
Transmission Electron ◽  
Resolution Study

The phenomenon of clustering in Al-Ag alloys has been extensively studied since the early work of Guinierl, wherein the pre-precipitation state was characterized as an assembly of spherical, ordered, silver-rich G.P. zones. Subsequent x-ray and TEM investigations yielded results in general agreement with this model. However, serious discrepancies were later revealed by the detailed x-ray diffraction - based computer simulations of Gragg and Cohen, i.e., the silver-rich clusters were instead octahedral in shape and fully disordered, atleast below 170°C. The object of the present investigation is to examine directly the structural characteristics of G.P. zones in Al-Ag by high resolution transmission electron microscopy.

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