Tem Assessment of Defects in (CdHg)Te Heterostructures

1990 ◽  
Vol 216 ◽  
Author(s):  
S.G. Lawson-Jack ◽  
I.P. Jones ◽  
D.J. Williams ◽  
M.G. Astles
Keyword(s):  
Electron Microscopy ◽  
Transmission Electron Microscopy ◽  
Buffer Layer ◽  
High Density ◽  
Misfit Dislocations ◽  
Cross Sectional ◽  
Burgers Vector ◽  
Density Of Dislocations ◽  
Transmission Electron ◽  
Interfacial Plane

ABSTRACTTransmission electron microscopy has been used to assess the defect contents of the various layers and interfaces in (CdHg) Te heterostructures. Examination of cross sectional specimens of these materials suggests that the density of misfit dislocations at the interfaces is related to the layer thicknesses, and that the high density of dislocations which are generated at the GaAs/CdTe interface are effectively prevented from penetrating into the CdHgTe epilayer by a 3um thick buffer layer. The majority of the dislocations in the layers were found to have a Burgers vector b = a/2<110> and either lie approximately parallel or inclined at an angle of ∼ 60° to the interfacial plane.

Transmission Electron Microscopy Study of Epitaxial Co/Au and Co/Pd (111) Multilayers

1992 ◽  
Vol 263 ◽  
Author(s):  
A.E.M. de Veirman ◽  
F. Hakkens ◽  
W. Coene ◽  
F.J.A. Den Broeder
Keyword(s):  
Electron Microscopy ◽  
Transmission Electron Microscopy ◽  
High Resolution Electron Microscopy ◽  
Microscopy Study ◽  
Electron Microscopy Study ◽  
Interface Plane ◽  
Misfit Dislocations ◽  
Transmission Electron Microscopy Study ◽  
Cross Sectional ◽  
Transmission Electron

ABSTRACTThe results of a transmission electron microscopy study of Co/Au and Co/Pd multilayers are reported. Special emphasis is put on the epitaxial growth and the relaxation of the misfit strain of these high misfit systems. In bright-field cross-sectional images, periodic contrast fringes are observed at the interfaces, which are the result of Moiré interference and which allow determination of the degree of misfit relaxation at the interface. It was established that 80-85% of the misfit is relaxed. From high resolution electron microscopy images the Burgers vector of the misfit dislocations was derived, being a/2<110> lying in the (111) interface plane. The results obtained for the Co/Au and Co/Pd multilayers will be discussed in comparison with those obtained for a bilayer of Co and Au.

Characterization of Dislocations in GaN Thin Film and GaN/AlN Multilayer

2012 ◽  
Vol 725 ◽  
pp. 75-78
Author(s):  
Noriko Ohmori ◽  
Tomonori Uchimaru ◽  
Hiroyuki Fujimori ◽  
Jun Komiyama ◽  
Yoshihisa Abe ◽  
...  
Keyword(s):  
Thin Film ◽  
Electron Microscopy ◽  
Transmission Electron Microscopy ◽  
Dislocation Density ◽  
Buffer Layer ◽  
Direction Parallel ◽  
Density Of Dislocations ◽  
Transmission Electron ◽  
Sudden Decrease

The dislocations in GaN thin film with GaN/AlN multilayer (ML) as the buffer layer were evaluated using transmission electron microscopy. A high density of dislocations parallel to the GaN/ML interface and a sudden decrease in the dislocation density at the GaN/ML interface were found. Dislocation propagation in the direction parallel to the GaN/ML interface by turning horizontally on the GaN/ML interface is considered to be effective in decreasing the dislocation density at the top layer of GaN.

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.

Structure and Electronic Properties of Misfit Dislocations in ZnSe/GaAs(001) Heterojunctions

1994 ◽  
Vol 340 ◽  
Author(s):  
Y. Chen ◽  
X. Liu ◽  
E. Weber ◽  
E. D. Bourret ◽  
D. J. Olego ◽  
...  
Keyword(s):  
Electron Microscopy ◽  
Transmission Electron Microscopy ◽  
Electrical Properties ◽  
Electronic Properties ◽  
Misfit Dislocation ◽  
Orthogonal Array ◽  
High Density ◽  
Misfit Dislocations ◽  
Transmission Electron ◽  
Dislocation Arrays

ABSTRACTStudies of the structure and electrical properties of regular and irregular misfit dislocations in undoped and N-doped ZnSe epilayers grown on GaAs(001) substrates by transmission electron microscopy (TEM), cathodoluminescence (CL) are reported. In undoped ZnSe epilayers, two sets of misfit dislocation arrays were observed: a straight orthogonal array along [110] and, and an irregular array roughly along [100] and [010] directions. The CL observations suggest that the irregular dislocations trap carriers more efficiently than the dislocations along <110>, possibly due to the high density of kinks existing along the zig-zag irregular dislocations. These irregular dislocations can be eliminated by doping nitrogen in the ZnSe epilayer with [N]≥l×1018 cm−3.

The Formation and Cathodoluminescence Activity of Buffer Layer Edge Dislocations in In0.12Ga0.88As/GaAs Heterostructures

1987 ◽  
Vol 104 ◽  
Author(s):  
E. A. Fitzgerald ◽  
P. D. Kirchner ◽  
G. D. Petit ◽  
J. M. Woodall ◽  
D. G. Ast
Keyword(s):  
Electron Microscopy ◽  
Transmission Electron Microscopy ◽  
Buffer Layer ◽  
Defect Structure ◽  
Radiative Recombination ◽  
Tem Analysis ◽  
Cross Sectional ◽  
Transmission Electron ◽  
Gaas Buffer Layer ◽  
Edge Dislocations

ABSTRACTThe defect structure of lattice-mismatched one micron In0.12 Ga0.88As epilayers on (001) GaAs was studied with scanning cathodoluminescence (CL) and transmission electron microscopy (TEM). CL examination of the GaAs buffer layer revealed the formation of a segmented network of defects below the interface. Cross-sectional TEM analysis shows that these defects are dislocation half-loops extending from the interface, and the vast majority of these loops lie on the GaAs side of the interface. The dislocations in the GaAs buffer layer were determined to be edge dislocations. Thus, CL images show that edge dislocations in this system are centers for non-radiative recombination. We propose that two 60° dislocations with opposite screw and interface tilt components can glide into the buffer layer to form edge dislocations. Potential energy plots for 60° dislocations near the interface and interacting with interface dislocations supports this model.

Structures of Nb/Al2O3 Interfaces Produced by Different Experimental Routes

1990 ◽  
Vol 183 ◽  
Author(s):  
J. Mayer ◽  
W. Mader ◽  
D. Knauss ◽  
F. Ernst ◽  
M. Rühle
Keyword(s):  
Electron Microscopy ◽  
Transmission Electron Microscopy ◽  
Molecular Beam ◽  
Al Alloy ◽  
Misfit Dislocations ◽  
Orientation Relationships ◽  
Cross Sectional ◽  
Mbe Growth ◽  
Sapphire Substrates ◽  
Transmission Electron

AbstractNb/Al2O3 interfaces were produced by (i) diffusion bonding of single crystalline Nb and Al2O3 at 1973 K, (ii) internal oxidation of a Nb-3at.% Al alloy at 1773 K, and (iii) molecular beam epitaxy (MBE) growth of 500 nm thick Nb overlayers on sapphire substrates at 1123 K. Cross-sectional specimens were prepared and studied by conventional (CTEM) and high resolution transmission electron microscopy (HREM). The orientation relationships between Nb and Al2O3 were identified by diffraction studies. HREM investigations revealed the structures of the different interfaces including the presence of misfit dislocations at or near the interface. The results for the different interfaces are compared.

High dose neutron irradiation damage in alpha alumina

1991 ◽  
Vol 6 (10) ◽  
pp. 2178-2187 ◽  
Author(s):  
R.A. Youngman ◽  
T.E. Mitchell ◽  
F.W. Clinard ◽  
G.F. Hurley
Keyword(s):  
Electron Microscopy ◽  
Transmission Electron Microscopy ◽  
Void Formation ◽  
High Density ◽  
Irradiation Damage ◽  
High Dose ◽  
Dislocation Loops ◽  
Density Of Dislocations ◽  
Transmission Electron ◽  
Alpha Alumina

Bulk samples of single crystalline and polycrystalline alpha alumina have been neutron-irradiated in the Experimental Breeder Reactor-II (EBR-II) to doses of 1026 n/m2 at temperatures of 925 K and 1100 K. The samples were found to swell macroscopically between 3% and 6%, depending on the temperature of irradiation and the form of the material. The damaged microstructures were investigated via transmission electron microscopy in order to understand the origin of the macroscopic swelling. In both single crystals and polycrystals the damage consists of a high density of dislocations containing predominately b = 1/3<101> dislocation loops on the (0001) planes coexistent with a high density of voids, which are aligned along the c-axis in this rhombohedral material. The established theory of void formation in metals is utilized to explain the formation of voids in alumina. The polycrystalline samples were extensively microcracked, and this is thought to be due to anisotropic swelling of the grains which in turn leads to stresses and fracturing at the grain boundaries.

Dislocations in alumina deformed by prismatic slip

1978 ◽  
Vol 36 (1) ◽  
pp. 606-607
Author(s):  
J. Cadoz ◽  
J. Castaing ◽  
J. Philibert
Keyword(s):  
Electron Microscopy ◽  
Transmission Electron Microscopy ◽  
Basal Slip ◽  
Prismatic Slip ◽  
Compression Tests ◽  
Thin Sections ◽  
Burgers Vector ◽  
Maximum Deformation ◽  
Transmission Electron ◽  
Mechanical Thinning

Plastic deformation of alumina has been much studied; basal slip occurs and dislocation structures have been investigated by transmission electron microscopy (T.E.M.) (1). Non basal slip has been observed (2); the prismatic glide system <1010> {1210} has been obtained by compression tests between 1400°C and 1800°C (3). Dislocations with <0110> burgers vector were identified using a 100 kV microscope(4).We describe the dislocation structures after prismatic slip, using high voltage T.E.M. which gives much information.Compression tests were performed at constant strainrate (∿10-4s-1); the maximum deformation reached was 0.03. Thin sections were cut from specimens deformed at 1450°C, either parallel to the glide plane or perpendicular to the glide direction. After mechanical thinning, foils were produced by ion bombardment. Details on experimental techniques can be obtained through reference (3).

Black-white contrast of dislocation loops

1978 ◽  
Vol 36 (1) ◽  
pp. 328-329
Author(s):  
J. J. Hren ◽  
W. D. Cooper ◽  
L. J. Sykes
Keyword(s):  
Electron Microscopy ◽  
Transmission Electron Microscopy ◽  
Dislocation Loops ◽  
Major Premise ◽  
Burgers Vector ◽  
Transmission Electron ◽  
Primary Means ◽  
Contrast Analysis ◽  
Dot Product ◽  
Imaging Conditions

Small dislocation loops observed by transmission electron microscopy exhibit a characteristic black-white strain contrast when observed under dynamical imaging conditions. In many cases, the topography and orientation of the image may be used to determine the nature of the loop crystallography. Two distinct but somewhat overlapping procedures have been developed for the contrast analysis and identification of small dislocation loops. One group of investigators has emphasized the use of the topography of the image as the principle tool for analysis. The major premise of this method is that the characteristic details of the image topography are dependent only on the magnitude of the dot product between the loop Burgers vector and the diffracting vector. This technique is commonly referred to as the (g•b) analysis. A second group of investigators has emphasized the use of the orientation of the direction of black-white contrast as the primary means of analysis.

Microstructure of laser-irradiated, conducting Kapton polyimide

1995 ◽  
Vol 53 ◽  
pp. 502-503
Author(s):  
D. L. Callahan ◽  
Z. Ball ◽  
H. M. Phillips ◽  
R. Sauerbrey
Keyword(s):  
Electron Microscopy ◽  
Phase Transition ◽  
Transmission Electron Microscopy ◽  
Cross Section ◽  
Film Surface ◽  
Cross Sectional ◽  
General Utility ◽  
Transmission Electron ◽  
Considerable Debate ◽  
Potential Applications

Ultraviolet laser-irradiation can be used to induce an insulator-to-conductor phase transition on the surface of Kapton polyimide. Such structures have potential applications as resistors or conductors for VLSI applications as well as general utility electrodes. Although the percolative nature of the phase transformation has been well-established, there has been little definitive work on the mechanism or extent of transformation. In particular, there has been considerable debate about whether or not the transition is primarily photothermal in nature, as we propose, or photochemical. In this study, cross-sectional optical microscopy and transmission electron microscopy are utilized to characterize the nature of microstructural changes associated with the laser-induced pyrolysis of polyimide.Laser-modified polyimide samples initially 12 μm thick were prepared in cross-section by standard ultramicrotomy. Resulting contraction in parallel to the film surface has led to distortions in apparent magnification. The scale bars shown are calibrated for the direction normal to the film surface only.

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