Sreels Analysis of Oxygen-Rich Inversion Domain Boundaries in Aluminum Nitride

1994 ◽  
Vol 357 ◽  
Author(s):  
J. Bruley ◽  
A.D. Westwood ◽  
R. A. Youngman ◽  
J.-C. Zhao ◽  
M.R. Notis
Keyword(s):  
Aluminum Nitride ◽  
Structural Model ◽  
Domain Boundary ◽  
Edge Structure ◽  
Spatially Resolved ◽  
Inversion Domain ◽  
Domain Boundaries ◽  
Length Data ◽  
Inversion Domain Boundaries ◽  
Electron Energy Loss

AbstractSpatially resolved electron energy loss spectroscopy analysis has been conducted on planar inversion domain boundaries in aluminum nitride. The defects were found to contain 1.5 monolayers of oxygen, in agreement with the most recent structural model of Westwood. From variations in near-edge structure, the local atomic environments of both oxygen and aluminum are compared with α-A1203, γ-A1203 and γ-AION standards. Based upon this study the stnrcture of the inversion domain boundary is found to resemble that of the cubic γ-AION spinel, and eliminates from consideration those structural models based upon ai-Al203. Furthermore, quantification of the shape resonances provided Al-O bond-length data from the inversion domain boundary interface. These distances closely agree with the Youngman Model that has recently been further refined by Westwood et al.

Investigations of the chemistry and bonding at niobiumsapphire interfaces

1994 ◽  
Vol 9 (10) ◽  
pp. 2574-2583 ◽  
Author(s):  
J. Bruley ◽  
R. Brydson ◽  
H. Müllejans ◽  
J. Mayer ◽  
G. Gutekunst ◽  
...  
Keyword(s):  
Energy Loss ◽  
Basal Plane ◽  
Molecular Beam ◽  
Structural Model ◽  
Edge Structure ◽  
Spatially Resolved ◽  
Two Samples ◽  
Metal Ceramic ◽  
Electron Energy Loss ◽  
Atomistic Structure

Spatially resolved electron energy-loss data have been recorded at the interface between niobium and sapphire (α-Al2O3), a model metal/ceramic couple. The spatial-difference technique is used to extract interface specific components of the energy-loss near-edge structure (ELNES), which are dependent on the chemistry and bonding across the interface. Multiple scattering calculations of aluminum, oxygen, and niobium clusters were performed to simulate the measured Al L2,3 ELNES. Two samples fabricated by different techniques were examined. The first interface was made by diffusion bonding pure crystals. Its interface spectrum is identified with tetrahedral coordination of the Al ions at the interface. The calculations match the experimental edge structures, supporting the notion of aluminum to niobium metal bonding and concurring with a structural model in which the basal plane of sapphire at the interface is terminated by a full monolayer (i.e., 67% excess) of aluminum. The second sample was produced by molecular beam epitaxy. The spectrum of this interface is consistent with an atomistic structure in which the interfacial basal plane of sapphire is terminated by oxygen. An unoccupied band of states within the band gap of Al2O3 is observed, signifying chemical bonding between metal and ceramic.

Enhanced Light Emission at Self-assembled GaN Inversion Domain Boundary

2011 ◽  
Vol 1324 ◽  
Author(s):  
Mei-Chun Liu ◽  
Yuh-Jen Cheng ◽  
Jet-Rung Chang ◽  
Chun-Yen Chang
Keyword(s):  
Molecular Beam ◽  
Light Emission ◽  
Domain Boundary ◽  
Mbe Growth ◽  
Polarity Inversion ◽  
Circular Pattern ◽  
Inversion Domain ◽  
Domain Boundaries ◽  
Self Assembled ◽  
Inversion Domain Boundaries

ABSTRACTWe report the fabrication of GaN lateral polarity inversion heterostructure with self assembled crystalline inversion domain boundaries (IDBs). The sample was fabricated by two step molecular-beam epitaxy (MBE) with microlithography patterning in between to define IDBs. Despite the use of circular pattern, hexagonal crystalline IDBs were self assembled from the circular pattern during the second MBE growth. Both cathodoluminescent (CL) and photoluminescent (PL) measurements show a significant enhanced emission at IDBs and in particular at hexagonal corners. The ability to fabricate self assembled crystalline IDBs and its enhanced emission property can be useful in optoelectronic applications.

Spatially resolved photoluminescence of inversion domain boundaries in GaN-based lateral polarity heterostructures

2001 ◽  
Vol 79 (7) ◽  
pp. 952-954 ◽  
Author(s):  
P. J. Schuck ◽  
M. D. Mason ◽  
R. D. Grober ◽  
O. Ambacher ◽  
A. P. Lima ◽  
...  
Keyword(s):  
Spatially Resolved ◽  
Inversion Domain ◽  
Domain Boundaries ◽  
Inversion Domain Boundaries

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.

Inversion Domain Boundaries and Oxygen Accommodation in Aluminum Nitride

1989 ◽  
Vol 167 ◽  
Author(s):  
R. A. Youngman ◽  
J. H. Harris ◽  
P. A. Labun ◽  
R. J. Graham ◽  
J. K. Weiss
Keyword(s):  
Aluminum Nitride ◽  
Domain Boundary ◽  
Stacking Faults ◽  
Interface Energy ◽  
Optical Methods ◽  
Extended Defect ◽  
Inversion Domain ◽  
Inversion Domain Boundaries ◽  
Structural Aspects

AbstractAluminum nitride is known to have a large affinity for oxygen as an impurity. At high levels (>∼4 wt/o) the oxygen is incorporated in the form of planar stacking faults where “pure” 2H AIN is regularly interspersed with a layer of oxygen at the faults. At oxygen levels lower than ∼ 4 wt/o the structure shows an expanded c-axis. The present authors have not observed this effect, rather a random distribution of stacking faults is observed along with another, more prevalent, extended defect identified as an inversion domain boundary (IDB). The IDBs are significantly aplanar (indicating a low interface energy), and often have precipitates and other, faceted defects associated with them. The role of these defects in oxygen accommodation in AIN has been investigated both structurally and chemically by electron optical methods (SEM, TEM, STEM, HREM, CBED, EDS, EELS, and CL-TEM). The structural nature of the boundaries, in the absence of oxygen, requires Al-Al or N-N bonding to occur with some frequency across the boundary. Such bonding is unlikely due to the excess energy required. Chemical analysis (EELS) and luminescence studies (CL-TEM) reveal that oxygen is often associated with the boundaries and may mediate the bonding at the boundary. A model is proposed for the IDB which includes structural aspects combined with considerations of stoichiometry in an effort to understand the origin and energetics of this defect.

Inversion Domain Boundary Dislocations in Heteroepitaxial Films

1988 ◽  
Vol 144 ◽  
Author(s):  
T. T. Cheng ◽  
P. Pirouz ◽  
F. Ernst
Keyword(s):  
Electron Microscope ◽  
Domain Boundary ◽  
Relative Displacement ◽  
Boundary Dislocation ◽  
Fringe Contrast ◽  
Burgers Vector ◽  
Inversion Domain ◽  
Transmission Electron ◽  
Domain Boundaries ◽  
Inversion Domain Boundaries

ABSTRACTTransmission electron microscope (TEM) images of inversion domain boundaries (IDB) show fringe contrast, thus indicating a relative displacement between the two adjoining domains. When the IDBs are facetted, different facets may have different displacement fault vectors. This implies that when the facetting changes from one plane to another, there should be a dislocation at the intersection of the planes. This is termed an “inversion domain boundary dislocation” and it will have a Burgers vector b=R1–R2 where R1, and R2 are the fault vectors of the two facets. Experimental results for facetted IDBs and IDB dislocations in SiC grown heteroepitaxially on (001) silicon are presented.

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.

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