Characterization of ErAs/GaAs and GaAs/ErAs/GaAs Structures

1989 ◽  
Vol 160 ◽  
Author(s):  
Jane G. Zhu ◽  
Chris J. Palmstrøm ◽  
Suzanne Mounier ◽  
C. Barry Carter
Keyword(s):  
Electron Microscopy ◽  
High Resolution Electron Microscopy ◽  
Gaas Layer ◽  
Misfit Dislocations ◽  
Weak Beam ◽  
Transmission Electron ◽  
Resolution Electron ◽  
Small Grains ◽  
Major Defect

AbstractA series of ErAs/GaAs and GaAs/ErAs/GaAs epilayers have been grown on (100) GaAs substrates by molecular-beam epitaxy. Misfit dislocations at the ErAs/GaAs interface have been analyzed using the weak-beam technique of transmission electron microscopy. The microstructure of GaAs/ErAs/GaAs layers have been characterized using conventional and high-resolution electron microscopy. Twinning inside the upper GaAs layer is the major defect. Although the desired epitactic (100) GaAs on (100) ErAs does dominate, small grains of GaAs with (111) or {122} orientations have been observed at the GaAs/ErAs heterojunction.

Interface structures in polycrystalline ceramic materials

1986 ◽  
Vol 44 ◽  
pp. 468-471
Author(s):  
K. J. Morrissey
Keyword(s):  
Electron Microscopy ◽  
Analytical Electron Microscopy ◽  
Physical And Mechanical Properties ◽  
High Resolution Electron Microscopy ◽  
Ceramic Materials ◽  
Polycrystalline Materials ◽  
Transmission Electron ◽  
Resolution Electron ◽  
Interface Structures

Grain boundaries and interfaces play an important role in determining both physical and mechanical properties of polycrystalline materials. To understand how the structure of interfaces can be controlled to optimize properties, it is necessary to understand and be able to predict their crystal chemistry. Transmission electron microscopy (TEM), analytical electron microscopy (AEM,), and high resolution electron microscopy (HREM) are essential tools for the characterization of the different types of interfaces which exist in ceramic systems. The purpose of this paper is to illustrate some specific areas in which understanding interface structure is important. Interfaces in sintered bodies, materials produced through phase transformation and electronic packaging are discussed.

AlN Nanorods synthesized by a Mechanothermal Process

2011 ◽  
Vol 1288 ◽  
Author(s):  
G. Rosas ◽  
J. Chihuaque ◽  
C. Patiño-Carachure ◽  
R. Esparza ◽  
R. Pérez
Keyword(s):  
Electron Microscopy ◽  
Mechanical Milling ◽  
Annealing Treatment ◽  
High Resolution Electron Microscopy ◽  
Dynamical Theory ◽  
Transmission Electron ◽  
Resolution Electron ◽  
Structural Configurations ◽  
Simulated Images

ABSTRACTWell-crystallized AlN nanorods have been produced by mechanical milling and subsequent annealing treatment of the milling powders (mechanothermal process). High purity AlN powders were used as the starting material. Mechanical milling was carried out in a vibratory SPEX mill for 30 h, using vials and balls of silicon nitride. The annealing treatment was carried out at 1200 ºC for 10 min. The characterization of the samples was performed by X-ray diffractometry and transmission electron microscopy (TEM). TEM observations indicated that the synthesized nanorods consisted of 30 nm in diameter and 100 nm in length. High resolution electron microscopy observations have been used in the structural characterization. AlN nanorods exhibit a well-crystallized structure. The growing direction of the nanorods is close to the [001] direction. The structural configurations have been explored through comparisons between experimental HREM images and theoretically simulated images obtained with the multislice method of the dynamical theory of electron diffraction.

Epitaxial Growth and Structure of Cubic and Pseudocubic Perovskite Films on Perovskite Substrates

1995 ◽  
Vol 401 ◽  
Author(s):  
P. A. Langjahr ◽  
T. Wagner ◽  
M. RÜhle ◽  
F. F. Lange
Keyword(s):  
Electron Microscopy ◽  
Epitaxial Growth ◽  
Lattice Mismatch ◽  
High Resolution Electron Microscopy ◽  
Lattice Parameter ◽  
Ternary Oxide ◽  
Misfit Dislocations ◽  
X Ray Diffraction ◽  
Transmission Electron ◽  
Resolution Electron

AbstractCubic and pseudocubic perovskite films on perovskite substrates are used to study the influence of the lattice mismatch on the epitaxial growth of thin films on substrates of the same structure. For the growth of the films, a metalorganic decomposition route (MOD) using 2-ethylhexanoates and neodecanoates as precursors, was developed. The decomposition of the precursors was investigated with thermogravimetric analysis (TGA) and x-ray diffraction (XRD). The films were spin-coated on (001)-oriented SrTiO3- and LaAlO3-substrates, pyrolyzed and afterwards annealed between 600°C and 1200°C. XRD-nvestigations and conventional transmission electron microscopy (CTEM) show, that epitaxial films with the orientation relationship [100](001) film ║ [100](001) substrate can be grown. With XRD, it could be shown, that not only ternary oxide films (SrZrO3, BaZrO3 and BaCeO3), but also perovskite solid solution films (SrTi0.5Zr0.5O3and BaCe0.5Zr0.5O3) can be prepared. Strong interdiffusion, detected by a shift of the film lattice parameter towards the substrate lattice parameter was found in SrZrO3- and BaZrO3-films on SrTiO3, annealed at temperatures above 1050°C. High resolution electron microscopy (HREM) studies of SrZrO3 on SrTiO3 show that a crystalline semicoherent interface with a periodical array of misfit dislocations is present.

Transmission electron microscopy study of Co/Pd and Co/Au multilayers

1993 ◽  
Vol 8 (5) ◽  
pp. 1019-1027 ◽  
Author(s):  
F. Hakkens ◽  
A. De Veirman ◽  
W. Coene ◽  
Broeder F.J.A. den
Keyword(s):  
Electron Microscopy ◽  
Transmission Electron Microscopy ◽  
High Resolution ◽  
High Resolution Electron Microscopy ◽  
Microscopy Study ◽  
Columnar Structure ◽  
Electron Microscopy Study ◽  
Misfit Dislocations ◽  
Transmission Electron ◽  
Resolution Electron

The structure of Co/Pd and Co/Au (111) multilayers is studied using transmission electron microscopy and high resolution electron microscopy. We focused on microstructure, atomic stacking (especially at the interfaces), and coherency, as these are structural properties that have considerable magnetic effects. A columnar structure with a strong curvature of the multilayer influenced by substrate temperature during growth is observed. High resolution imaging shows numerous steps at the interfaces of the multilayer structure and the presence of misfit dislocations. In bright-field images, periodic contrast fringes are observed at these interfaces as the result of moiré interference. These moiré fringes are used to study the misfit relaxation at the interfaces, whereas electron diffraction gives the average relaxation over the whole layer. Both measurements determined that, for Co/Pd as well as Co/Au multilayers, 80–85% of the misfit is relaxed and 20–15% remains in the form of strain, independent of the Co layer thickness in the regime studied.

Structural Characterization Of Laser Lift-Off GaN

2000 ◽  
Vol 617 ◽  
Author(s):  
Eric A. Stach ◽  
M. Kelsch ◽  
W.S. Wong ◽  
E.C. Nelson ◽  
T. Sands ◽  
...  
Keyword(s):  
Electron Microscopy ◽  
Chemical Characterization ◽  
High Resolution Electron Microscopy ◽  
Economic Benefits ◽  
Thin Layers ◽  
Transmission Electron ◽  
Resolution Electron ◽  
Lift Off ◽  
Microscopy Techniques

AbstractLaser lift-off and bonding has been demonstrated as a viable route for the integration of III-nitride opto-electronics with mainstream device technology. A critical remaining question is the structural and chemical quality of the layers following lift-off. In this paper, we present detailed structural and chemical characterization of both the epitaxial layer and the substrate using standard transmission electron microscopy techniques. Conventional diffraction contrast and high resolution electron microscopy indicate that the structural alteration of the material is limited to approximately the first 50 nm. Energy dispersive electron spectroscopy line profiles show that intermixing is also confined to similar thicknesses. These results indicate that laser lift-off of even thin layers is likely to result in materials suitable for device integration. Additionally, because the damage to the sapphire substrate is minimal, it should be possible to polish and re-use these substrates for subsequent heteroepitaxial growths, resulting in significant economic benefits.

Synthesis and characterization of antimony oxide nanoparticles

2001 ◽  
Vol 16 (3) ◽  
pp. 803-805 ◽  
Author(s):  
Zaoli Zhang ◽  
Lin Guo ◽  
Wendong Wang
Keyword(s):  
Electron Microscopy ◽  
Water Solution ◽  
High Resolution Electron Microscopy ◽  
Antimony Oxide ◽  
Oxide Nanoparticles ◽  
Internal Standards ◽  
Transmission Electron ◽  
Initial Stage ◽  
Resolution Electron

Antimony oxide nanoparticles were synthesized in the presence of the polyvinyl alcohol in water solution through the reaction between SbCl3 and NaOH. The size of the particle ranges from 10 to 80 nm, and the largest one can even reach 200 nm, which may begin to grow in the initial stage of the reflux. Transmission electron microscopy and high-resolution electron microscopy (HREM) were used to characterize the microstructure of these nanoparticles. Using silicon single crystals as internal standards, the polycrystalline diffraction pattern analysis shows only presence of cubic Sb2O3 phase. The bright-field micrograph displays that the particles may have various polyhedral configurations. HREM results show that the particles are crystallographically perfect. Moreover, the formation mechanism of nanoparticles is discussed.

Tem Structure Characterization Of Ti/Al and Ti/Al/Ni/Au Ohmic Contacts For n-GaN

1996 ◽  
Vol 423 ◽  
Author(s):  
S. Ruvimov ◽  
Z. Liliental-Weber ◽  
J. Washburn ◽  
K. J. Duxstad ◽  
E. E. Hailer ◽  
...  
Keyword(s):  
Electron Microscopy ◽  
Transmission Electron Microscopy ◽  
High Resolution ◽  
Ohmic Contacts ◽  
High Resolution Electron Microscopy ◽  
Structure Characterization ◽  
Transmission Electron ◽  
Resolution Electron ◽  
Thin Polycrystalline

AbstractTransmission electron microscopy has been applied to characterize the structure of Ti/Al and Ti/Al/Ni/Au ohmic contacts on n-type GaN (˜1017 cm−3 ) epitaxial layers. A thin polycrystalline cubic TiN layer epitaxially matched to the (0001) GaN surface was detected at the interface with the GaN substrate. This layer was studied in detail by electron diffraction and high resolution electron microscopy. The orientation relationship between the cubic TiN and the GaN was found to be: {111}TiN//{00.1}GaN, [110]TiN//[11.0]GaN, [112 ]TiN//[ 10.0]GaN. The formation of this cubic TiN layer results in an excess of N vacancies in the GaN close to the interface which is considered to be the reason for the low resistance of the contact.

The Effect of Xe Ion Beam Treatment on the Interaction Between Gold and GaAs

1992 ◽  
Vol 260 ◽  
Author(s):  
B. Pécz ◽  
G. Radnóczi ◽  
Zs. J. Horváth ◽  
P. B. Barna ◽  
Erika Jároli ◽  
...  
Keyword(s):  
Electron Microscopy ◽  
Ion Beam ◽  
High Resolution Electron Microscopy ◽  
Gaas Layer ◽  
High Dose ◽  
Cross Sectional ◽  
Transmission Electron ◽  
Resolution Electron ◽  
Ion Beam Treatment ◽  
Defective Area

ABSTRACTThe effect of the defective nature of the substrate on the alloying behaviour of Xe implanted Au(55 ran)/n-GaAs system was studied using cross sectional transmission electron microscopy.Low dose Xe implantation (700 keV, 1*1014 ions/cm2) caused the formation of about SO nm thick polycrystalline region of GaAs beneath the gold layer. Annealing the implanted sample at 450°C gold diffused through the polycrystalline GaAs region and formed large pits of Au(Ga) solid solution in the defective area of GaAs having stacking faults and twins. The formation of a regrown GaAs covering layer was observed on the top of the reacted metallization simultaneously.High dose implantation of Xe++ ions resulted in the formation of amorphous GaAs layer with a thickness of about 750 nm. Twinned regions of GaAs were observed at the amorphous - crystalline GaAs interface by high resolution electron microscopy. Ion beam caused phase transition was observed in this sample. The amorphous GaAs region recrystallized to single crystalline GaAs due to annealing at 400°C.

Strain Relief Mechanisms and Nature of Misfit Dislocations in GaAs/Si Heterostructures

1988 ◽  
Vol 130 ◽  
Author(s):  
S. Sharan ◽  
J. Narayan ◽  
J. P. Salerno ◽  
J. C. C. Fan
Keyword(s):  
Electron Microscopy ◽  
Cross Section ◽  
Elastic Strain ◽  
Strain Relaxation ◽  
Minimum Energy ◽  
High Resolution Electron Microscopy ◽  
Misfit Dislocations ◽  
Transmission Electron ◽  
Resolution Electron ◽  
Theoretical Predictions

AbstractThe nucleation and glide of misfit dislocations in GaAs/Si system is investigated using transmission electron microscopy. GaAs epilayers of different thicknesses were examined by electron microscopy (plan and cross-section) and the elastic strain remaining in the film has been related to the average spacing of the misfit dislocations at the interface. A model is developed based on minimum energy considerations to determine the strain-thickness relationship. The theoretical predictions of strain relaxation are compared with experimental observations using high resolution electron microscopy.

High-resolution electron microscopy of nanostructured materials

1995 ◽  
Vol 53 ◽  
pp. 172-173
Author(s):  
M. José-Yacamán
Keyword(s):  
Electron Microscopy ◽  
High Resolution ◽  
Grain Boundaries ◽  
Nanostructured Materials ◽  
High Resolution Electron Microscopy ◽  
Hrem Image ◽  
Small Particles ◽  
Resolution Electron ◽  
Nanophase Materials

Electron microscopy is a fundamental tool in materials characterization. In the case of nanostructured materials we are looking for features with a size in the nanometer range. Therefore often the conventional TEM techniques are not enough for characterization of nanophases. High Resolution Electron Microscopy (HREM), is a key technique in order to characterize those materials with a resolution of ~ 1.7A. High resolution studies of metallic nanostructured materials has been also reported in the literature. It is concluded that boundaries in nanophase materials are similar in structure to the regular grain boundaries. That work therefore did not confirm the early hipothesis on the field that grain boundaries in nanostructured materials have a special behavior. We will show in this paper that by a combination of HREM image processing, and image calculations, it is possible to prove that small particles and coalesced grains have a significant surface roughness, as well as large internal strain.

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