The Nature of Oxygen-Related Polytypoids in the Aluminum Nitride-Aluminum Oxide System

1993 ◽  
Vol 319 ◽  
Author(s):  
R.A. Youngman
Keyword(s):  
Oxygen Content ◽  
Stacking Faults ◽  
High Resolution Electron Microscopy ◽  
Oxide System ◽  
Extended Defects ◽  
Low Oxygen ◽  
Inversion Domain ◽  
Resolution Electron ◽  
Related Point ◽  
Inversion Domain Boundaries

AbstractPrevious investigations into the nature of polytypoid structures in the A1N-A12O3 and A1NSiO2 systems have concluded that these structures are comprised of ordered stacking faults which accommodate oxygen (and silicon) in the basic wurtzite (2H) AIN structure. The polytypoids are distinct chemical phases intimately related to the pure 2H AIN. More recent work in low oxygen content (<6 at.%) A1N has elucidated the evolution of oxygen-related point defects, and transformation of these defects into extended structures. These studies have shown that all oxygenrelated extended defects in the A1N-A12O3 system are inversion domain boundaries (IDBs).We present here extensions of the concepts developed from low oxygen content studies which lead to direct application in understanding the polytypoid structures. High resolution electron microscopy (HREM), specific electron diffraction experiments, and structural models are utilized to prove that the polytypoid structures are not based on stacking faults, but, in fact are based on IDBs.

Interaction Between Basal Stacking Faults and Prismatic Inversion Domain Boundaries in GaN

2000 ◽  
Vol 639 ◽  
Author(s):  
Philomela Komninou ◽  
Joseph Kioseoglou ◽  
Eirini Sarigiannidou ◽  
George P. Dimitrakopulos ◽  
Thomas Kehagias ◽  
...  
Keyword(s):  
Electron Microscopy ◽  
High Resolution ◽  
Stacking Faults ◽  
High Resolution Electron Microscopy ◽  
High Energy ◽  
Low Energy ◽  
Inversion Domain ◽  
Resolution Electron ◽  
Domain Boundaries ◽  
Inversion Domain Boundaries

ABSTRACTThe interaction of growth intrinsic stacking faults with inversion domain boundaries in GaN epitaxial layers is studied by high resolution electron microscopy. It is observed that stacking faults may mediate a structural transformation of inversion domain boundaries, from the low energy types, known as IDB boundaries, to the high energy ones, known as Holt-type boundaries. Such interactions may be attributed to the different growth rates of adjacent domains of inverse polarity.

Deformation and microstructure of rutile

1990 ◽  
Vol 429 (1876) ◽  
pp. 175-202 ◽  
Keyword(s):  
Electron Microscopy ◽  
High Resolution Electron Microscopy ◽  
Extended Defects ◽  
Low Oxygen ◽  
Transmission Electron ◽  
Medium Resolution ◽  
Resolution Electron ◽  
Wide Range ◽  
Range Of Values ◽  
Low Oxygen Pressure

Studies of the mechanical properties of rutiles are described, in particular the behaviour of the elastic limit under compression with respect to variations in temperature (pure rutile), intrinsic non-stoichiometry (pure rutile reduced under low oxygen pressure) and extrinsic non­-stoichiometry (rutile doped with chromia and alumina). A wide range of values is obtained, which may be understood in terms of the interaction of dislocations belonging to the slip systems {101} <1̄01> and {110} <001> with impurities, non-stoichiometric small and extended defects and precipitates. Transmission electron microscopy at medium resolution as well as high-resolution electron microscopy have been used to relate mechanical behaviour with microstructure.

Oxygen incorporation in aluminum nitride via extended defects: Part III. Reevaluation of the polytypoid structure in the aluminum nitride-aluminum oxide binary system

1995 ◽  
Vol 10 (10) ◽  
pp. 2573-2585 ◽  
Author(s):  
Alistair D. Westwoord ◽  
Robert A. Youngman ◽  
Martha R. McCartney ◽  
Alasiair N. Cormack ◽  
Michael R. Notis
Keyword(s):  
Aluminum Nitride ◽  
Stacking Faults ◽  
Structural Rearrangement ◽  
Extended Defects ◽  
Structural Elements ◽  
Inversion Domain ◽  
Transmission Electron ◽  
New Variant ◽  
Domain Boundaries ◽  
Inversion Domain Boundaries

This paper extends the concepts that were developed to explain the structural rearrangement of the wurtzite AlN lattice due to incorporation of small amounts of oxygen, and to directly use them to assist in understanding the polytypoid structures. Conventional and high-resolution transmission electron microscopy, specific electron diffraction experiments, and atomistic computer simulations have been used to investigate the structural nature of the polytypoids. The experimental observations provide compelling evidence that polytypoid structures are not arrays of stacking faults, but are rather arrays of inversion domain boundaries (IDB's). A new model for the polytypoid structure is proposed with the basic repeat structural unit consisting of a planar IDB-P and a corrugated IDB. This model shares common structural elements with the model proposed by Thompson, even though in his model the polytypoids were described as consisting of stacking faults. Small additions (≃ 1000 ppm) of silicon were observed to have a dramatic effect on the polytypoid structure. First, it appears that the addition of Si causes the creation of a new variant of the planar IDB (termed IDB-P'), different from the IDB-P defect observed in the AlN-Al2O3 polytypoids; second, the addition of Si influences the structure of the corrugated IDB, such that it appears to become planar.

The Atomic Structure of Extended Defects in GaN

1999 ◽  
Vol 595 ◽  
Author(s):  
P. Ruterana ◽  
G. Nouet
Keyword(s):  
Grain Boundaries ◽  
Atomic Structure ◽  
Stacking Faults ◽  
Threading Dislocations ◽  
Extended Defects ◽  
High Angle ◽  
Inversion Domain ◽  
Domain Boundaries ◽  
Inversion Domain Boundaries ◽  
Edge Dislocations

AbstractGaN layers contain large densities (1010 cm−2) of threading dislocations, nanopipes, (0001) and { 1120 } stacking faults, and { 1010 } inversion domains. Three configurations have been found for pure edge dislocations, mainly inside high angle grain boundaries where the 4 atom ring cores can be stabilized. Two atomic configurations, related by a 1/6 < 1010 > stair rod dislocation, have been observed for the { 1120 } stacking fault in (Ga-Al)N layers. For the {1010} inversion domain boundaries, a configuration corresponding to the Holt model was observed, as well as another with no N-N or Ga-Ga bonds.

Fine structure and properties of defects in naturally occurring silicates and oxides

1990 ◽  
Vol 48 (4) ◽  
pp. 460-461
Author(s):  
David R. Veblen
Keyword(s):  
Chemical Reactions ◽  
High Resolution Electron Microscopy ◽  
Extended Defects ◽  
Single Chain ◽  
Naturally Occurring ◽  
Resolution Electron ◽  
Fine Structures ◽  
Image Simulations ◽  
Similar Crystal Structure

Extended defects and interfaces control many processes in rock-forming minerals, from chemical reactions to rock deformation. In many cases, it is not the average structure of a defect or interface that is most important, but rather the structure of defect terminations or offsets in an interface. One of the major thrusts of high-resolution electron microscopy in the earth sciences has been to identify the role of defect fine structures in reactions and to determine the structures of such features. This paper will review studies using HREM and image simulations to determine the structures of defects in silicate and oxide minerals and present several examples of the role of defects in mineral chemical reactions. In some cases, the geological occurrence can be used to constrain the diffusional properties of defects.The simplest reactions in minerals involve exsolution (precipitation) of one mineral from another with a similar crystal structure, and pyroxenes (single-chain silicates) provide a good example. Although conventional TEM studies have led to a basic understanding of this sort of phase separation in pyroxenes via spinodal decomposition or nucleation and growth, HREM has provided a much more detailed appreciation of the processes involved.

Junction lines of inversion domain boundaries with stacking faults in GaN

2004 ◽  
Vol 70 (11) ◽  
Author(s):  
J. Kioseoglou ◽  
G. P. Dimitrakopulos ◽  
Ph. Komninou ◽  
H. M. Polatoglou ◽  
A. Serra ◽  
...  
Keyword(s):  
Stacking Faults ◽  
Inversion Domain ◽  
Domain Boundaries ◽  
Inversion Domain Boundaries

Crystal Structure of and Defects in the Pentacene Thin Film Phase

2002 ◽  
Vol 734 ◽  
Author(s):  
Lawrence F. Drummy ◽  
Paul K. Miska ◽  
David C. Martin
Keyword(s):  
Thin Film ◽  
Electron Microscopy ◽  
Low Voltage ◽  
Field Effect Transistors ◽  
High Resolution Electron Microscopy ◽  
Orthorhombic Symmetry ◽  
Extended Defects ◽  
X Ray Diffraction ◽  
Voltage Electron ◽  
Resolution Electron

The aromatic hydrocarbon pentacene is currently under investigation for use as the active layer in electronic devices such as thin film field effect transistors. We have used X-Ray Diffraction (XRD), Electron Diffraction (ED), Low Voltage Electron Microscopy (LVEM), High Resolution Electron Microscopy (HREM) and molecular modeling to investigate the thin film phase of pentacene. We will report the orthorhombic symmetry and lattice parameters of the thin film phase measured experimentally from these techniques. The structure of extended defects such as dislocations and grain boundaries will influence the electrical and mechanical characteristics of the films. Here we show a direct image of an edge dislocation in the thin film phase and discuss the way in which the lattice accommodates the defect.

Misfit Dislocations at II-VI/GaAs Interfaces

1990 ◽  
Vol 183 ◽  
Author(s):  
A. F. Schwartzman
Keyword(s):  
Lattice Mismatch ◽  
High Resolution Electron Microscopy ◽  
Interfacial Structure ◽  
Misfit Dislocations ◽  
Extended Defects ◽  
Partial Dislocations ◽  
Resolution Electron ◽  
Before And After ◽  
Slip Planes ◽  
Efficient Type

AbstractHigh-resolution electron microscopy -is used to characterize the defect structure of CdTe/GaAs and ZnTe/GaAs heterojunctions before and after annealing. For as-deposited films, a variety of defects exist both in the form of perfect misfit dislocations at the interface and extended defects into the thin film. The extended defects result from dissociation of 60° dislocations and reactions between perfect and partial dislocations lying on intersecting slip planes. The annealed interfaces consist of a periodic array of perfect edge Lomer dislocations, the most efficient type of misfit dislocation for accomodating the lattice mismatch, 14.6 % for CdTe/GaAs and 8 % for ZnTe/GaAs. In both cases, the spacing between dislocations corresponds to the value predicted for completely strain-free thin fims, 31 and 54 Å for CdTe and ZnTe respectively. This paper concentrates on the different dislocation reactions which transform the interfacial structure from the as-deposited case to the annealed case.

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