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.

Planar and Curved Defects in Aluminum Nitride: Their Microstructure and Microchemistry

1989 ◽  
Vol 167 ◽  
Author(s):  
Alistair D. Westwood ◽  
Michael R. Notis
Keyword(s):  
Electron Microscopy ◽  
Aluminum Nitride ◽  
Analytical Electron Microscopy ◽  
Microchemical Analysis ◽  
Inversion Domain ◽  
Transmission Electron ◽  
Proposed Model ◽  
Domain Boundaries ◽  
Convergent Beam ◽  
Inversion Domain Boundaries

AbstractThe microstructure and microchemistry of planar and curved defects in Aluminum Nitride (AIN) has been investigated using Conventional Transmission Electron Microscopy (CTEM), Convergent Beam Electron Diffraction (CBED), and Analytical Electron Microscopy (AEM) techniques. Both defect morphologies were identified as Inversion Domain Boundaries (IDB). Microchemical analysis revealed oxygen segregation to the planar faults; when present on the curved defects, oxygen was at a lower concentration than in the planar defect case. Annealing experiments on defect containing AIN support our microchemical analysis of oxygen segregation. A proposed model for the formation of these two types of boundaries is presented.

Oxygen incorporation in aluminum nitride via extended defects: Part II. Structure of curved inversion domain boundaries and defect formation

1995 ◽  
Vol 10 (5) ◽  
pp. 1287-1300 ◽  
Author(s):  
Alistair D. Westwood ◽  
Robert A. Youngman ◽  
Martha R. McCartney ◽  
Alastair N. Cormack ◽  
Michael R. Notis
Keyword(s):  
Electron Microscopy ◽  
Transmission Electron Microscopy ◽  
Aluminum Nitride ◽  
Displacement Vector ◽  
Interfacial Structure ◽  
Formation Mechanisms ◽  
Inversion Domain ◽  
Transmission Electron ◽  
Domain Boundaries ◽  
Inversion Domain Boundaries

Three distinct morphologies of curved (curved, facetted, and corrugated) inversion domain boundaries (IDB's), observed in aluminum nitride, have been investigated using conventional transmission electron microscopy, convergent beam electron diffraction, high-resolution transmission electron microscopy, analytical electron microscopy, and atomistic computer simulations. The interfacial structure and chemistry of the curved and facetted defects have been studied, and based upon the experimental evidence, a single model has been proposed for the curved IDB which is consistent with all three observed morphologies. The interface model comprises a continuous nitrogen sublattice, with the aluminum sublattice being displaced across a {1011} plane, and having a displacement vector R = 0.23〈0001〉. This displacement translates the aluminum sublattice from upwardly pointing to downwardly pointing tetrahedral sites, or vice versa, in the wurtzite structure. The measured value of the displacement vector is between 0.05〈0001〉 and 0.43〈0001〉; the variation is believed to be due to local changes in chemistry. This is supported by atomistic calculations which indicate that the interface is most stable when both aluminum vacancies and oxygen ions are present at the interface, and that the interface energy is independent of displacement vector in the range of 0.05〈0001〉 to 0.35〈0001〉. The curved IDB's form as a result of nonstoichiometry within the crystal. The choice of curved IDB morphology is believed to be controlled by local changes in chemistry, nonstoichiometry at the interface, and proximity to other planar IDB's (the last reason is explained in Part III). A number of possible formation mechanisms are discussed for both planar and curved IDB's. The Burgers vector for the dislocation present at the intersection of the planar and curved IDB's was determined to be b = 1/3〈1010〉 + t〈0001〉, where tmeas = 0.157 and tcalc = 0.164.

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.

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.

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

Microstructral Investigations on GaN Films Grown by Laser Induced Molecular Beam Epitaxy

1999 ◽  
Vol 595 ◽  
Author(s):  
H. Zhou ◽  
F. Phillipp ◽  
M. Gross ◽  
H. Schröder
Keyword(s):  
Molecular Beam Epitaxy ◽  
Molecular Beam ◽  
Threading Dislocations ◽  
Planar Defects ◽  
Sapphire Substrates ◽  
Inversion Domain ◽  
Transmission Electron ◽  
Domain Boundaries ◽  
Line Defects ◽  
Inversion Domain Boundaries

AbstractMicrostructural investigations on GaN films grown on SiC and sapphire substrates by laser induced molecular beam epitaxy have been performed. Threading dislocations with Burgers vectors of 1/3<1120>, 1/3<1123> and [0001] are typical line defects, predominantly the first type of dislocations. Their densities are typically 1.5×1010 cm−2 and 4×109 cm−2 on SiC and sapphire, respectively. Additionally, planar defects characterized as inversion domain boundaries lying on {1100} planes have been observed in GaN/sapphire samples with an inversion domain density of 4×109 cm−2. The inversion domains are of Ga-polarity with respect to the N-polarity of the adjacent matrix. However, GaN layers grown on SiC show Ga-polarity. Possible reasons for the different morphologies and structures of the films grown on different substrates are discussed. Based on an analysis of displacement fringes of inversion domains, an atomic model of the IDB-II with Ga-N bonds across the boundary was deduced. High resolution transmission electron microscopy (HRTEM) observations and the corresponding simulations confirmed the IDB-II structure determined by the analysis of displacement fringes.

Inversion Domain Boundaries in GaN Grown on Sapphire

1996 ◽  
Vol 449 ◽  
Author(s):  
L. T. Romano ◽  
J.E. Northrup
Keyword(s):  
Dark Field ◽  
Hydride Vapor Phase Epitaxy ◽  
Dark Field Imaging ◽  
Inversion Domain ◽  
Transmission Electron ◽  
Domain Boundaries ◽  
Convergent Beam ◽  
Inversion Domain Boundaries ◽  
Field Imaging ◽  
Beam Diffraction

ABSTRACTInversion domain boundaries (IDBs) in GaN grown on sapphire (0001) were studied by a combination of high resolution transmission electron microscopy, multiple dark field imaging, and convergent beam diffraction. Films grown by molecular beam epitaxy (MBE), metalorganic vapor deposition (MOCVD), and hydride vapor phase epitaxy (HVPE) were investigated and all found to contain IDBs. Inversion domains (IDs) that extended from the surface to the interface were found to be columnar with facets on the {10–10} and {11–20} planes. Other domains ended within the film that formed IDBs on the (0001) and {1–102} planes. The domains were found to grow in clusters and connect at points along the boundary.

Island Coalescence Induced Substructure Within GaP Epitaxial Layers Grown on (001), (111), (110) and (113) Si

2000 ◽  
Vol 618 ◽  
Author(s):  
V. Narayanan ◽  
S. Mahajan ◽  
K. J. Bachmann ◽  
V. Woods ◽  
N. Dietz
Keyword(s):  
Defect Formation ◽  
Chemical Beam Epitaxy ◽  
Inversion Domain ◽  
Transmission Electron ◽  
Domain Boundaries ◽  
Lattice Images ◽  
Tilt Boundaries ◽  
Island Coalescence ◽  
Inversion Domain Boundaries ◽  
Multiple Twinning

ABSTRACTGaP islands grown on selected surfaces of Si and their coalescence behavior have been investigated by transmission electron microscopy. These layers were grown by chemical beam epitaxy. A number of significant observations emerge from this study. First, planar defect formation has been shown to be related to stacking errors on the smaller P-terminated {111} facets of GaP islands. Amongst the four orientations, (111) epilayers have a higher density of stacking faults and first order twins because of more P-terminated {111} facets per island. Second, multiple twinning on exposed {111} facets can produce tilt boundaries and irregular growths when islands coalesce. Third, inversion domain boundaries lying on {110} planes have been shown to form during GaP island coalescence across monatomic steps on (001) Si. Image simulations have been performed to show that these boundaries can be seen in high resolution lattice images and the observed contrast is attributed to the presence of wrong Ga-Ga and P-P bonds at the inversion boundary.

On the nature of the oxygen-related defect in aluminum nitride

1990 ◽  
Vol 5 (8) ◽  
pp. 1763-1773 ◽  
Author(s):  
J. H. Harris ◽  
R. A. Youngman ◽  
R. G. Teller
Keyword(s):  
Thermal Conductivity ◽  
Aluminum Nitride ◽  
Lattice Parameter ◽  
Extended Defects ◽  
Inversion Domain ◽  
Transmission Electron ◽  
Oxygen Related Defect ◽  
Diffraction Lattice ◽  
Related Defect ◽  
Oxygen Concentrations

The oxygen-related defect in an aluminum nitride (AIN) single crystal and in polycrystalline ceramics is investigated utilizing photoluminescence spectroscopy, thermal conductivity measurements, x-ray diffraction lattice parameter measurements, and transmission electron microscopy. The results of these measurements indicate that at oxygen concentrations near 0.75 at.%, a transition in the oxygen accommodating defect occurs. On both sides of this transition, simple structural models for the oxygen defect are proposed and shown to be in good agreement with the thermal conductivity and lattice parameter measurements, and to be consistent with the formation of various extended defects (e.g., inversion domain boundaries) at higher oxygen concentrations.

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.

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