Single domain structure of 2H-AlN films on Si(001) substrates

2001 ◽  
Vol 680 ◽  
Author(s):  
Joerg Jinschek ◽  
Vadim Lebedev ◽  
Ute Kaiser ◽  
Wolfgang Richter
Keyword(s):  
Surface Defects ◽  
Substrate Surface ◽  
Lattice Misfit ◽  
Film Structure ◽  
Single Domain ◽  
Misfit Dislocations ◽  
Transmission Electron ◽  
Aln Film ◽  
Lattice Planes

ABSTRACTAluminum nitride (2H-AlN) films were grown by plasma-assisted molecular beam epitaxy (MBE) on Si(001). By conventional (CTEM) and high resolution transmission electron microscopy (HRTEM) investigations the influence of the off-axis angle of the substrate surface on the film structure was studied. Three types of Si(001) substrates were used: on-axis, ∼1°, and ∼5° off-axis. The 2H-AlN layer on an exact oriented Si(001) substrates consists of 3 AlN film domains: two main film domains, AlNI and AlNII, and a small domain AlNIII at substrate surface defects. Their c-axis orientations are parallel to the c-axis of the substrate: [0001]AlNI,II,III ∥ [001]Si. The a-axes of AlNI and AlNII rotated by 30° to each other: [11 20]AlNII∥[01 10]AlNII ∥ [1 1 0]Si. The orientation of AlNIII is [01 10]AlNIII ∥ [100]Si. In 2H-AlN films grown on off-axis Si(001) substrates (∼1° and ∼5°) the ratio between the AlNI and AlNII film domains changes dramatically as far as a single domain film structure consisting of mainly AlNI is reached. The AlN c-axes of all domains on the off-axis substrates are not parallel to the Si c-axis but tilted by the off-axis angle of the Si(001) substrate (∼1° respectively ∼5°), i.e. [0001]AlN is parallel to the Si(001) substrate surface orientation. Determination of the AlNI domain / Si(001) interface structure by HRTEM illuminates the origin of the preference of this domain in the 2H-AlN film by using off-axis Si(001) substrates. On the on-axis substrate a regular array of misfit dislocations causes a 5:4 fit between the (1 1 00)AlN and ( 1 1 0)Si lattice planes. The off-axis Si(001) leads to a rotation of the AlN lattice in respect of the Si lattice. An array of misfit dislocations with a 4:3 fit between (1 1 01)AlN and ( 1 1 1)Si lattice planes decreases the residual lattice misfit from -1.6% to -0.8%.

Transmission electron microscopy of misfit dislocation and strain relaxation in lattice mismatched III-V heterostructures versus substrate surface treatment

2011 ◽  
Vol 1324 ◽  
Author(s):  
Y. Wang ◽  
P. Ruterana ◽  
L. Desplanque ◽  
S. El Kazzi ◽  
X. Wallart
Keyword(s):  
Electron Microscopy ◽  
Transmission Electron Microscopy ◽  
Surface Treatment ◽  
Substrate Surface ◽  
Strain Relaxation ◽  
Dislocation Core ◽  
Misfit Dislocations ◽  
Heteroepitaxial Growth ◽  
Transmission Electron ◽  
Growth Initiation

ABSTRACTHigh resolution transmission electron microscopy in combination with geometric phase analysis is used to investigate the interface misfit dislocations, strain relaxation, and dislocation core behavior versus the surface treatment of the GaAs for the heteroepitaxial growth of GaSb. It is pointed out that Sb-rich growth initiation promotes the formation of a high quality network of Lomer misfit dislocations that are more efficient for strain relaxation.

Mechanisms of misfit strain relaxation in epitaxially grown BLT (Bi4-xLaxTi3O12, x = 0.75) thin films

2003 ◽  
Vol 779 ◽  
Author(s):  
Hyung Seok Kim ◽  
Sang Ho Oh ◽  
Ju Hyung Suh ◽  
Chan Gyung Park
Keyword(s):  
Electron Microscopy ◽  
Thin Films ◽  
Transmission Electron Microscopy ◽  
Strain Relaxation ◽  
Lattice Misfit ◽  
Misfit Strain ◽  
Misfit Dislocations ◽  
Transmission Electron ◽  
Means Of Transmission ◽  
20 Nm

AbstractMechanisms of misfit strain relaxation in epitaxially grown Bi4-xLaxTi3O12 (BLT) thin films deposited on SrTiO3 (STO) and LaAlO3 (LAO) substrates have been investigated by means of transmission electron microscopy (TEM). The misfit strain of 20 nm thick BLT films grown on STO substrate was relaxed by forming misfit dislocations at the interface. However, cracks were observed in 100 nm thick BLT films grown on the same STO. It was confirmed that cracks were formed because of high misfit strain accumulated with increasing the thickness of BLT, that was not sufficiently relaxed by misfit dislocations. In the case of the BLT film grown on LAO substrate, the magnitude of lattice misfit between BLT and LAO was very small (~1/10) in comparison with the case of the BLT grown on STO. The relatively small misfit strain formed in layered structure of the BLT films on LAO, therefore, was easily relaxed by distorting the film, rather than forming misfit dislocations or cracks, resulting in misorientation regions in the BLT film.

Determination of The State of Deformation in Epitaxial Layers Using High Resolution X-Ray Diffraction

1993 ◽  
Vol 319 ◽  
Author(s):  
P.J. Dugdale ◽  
R.C. Pond ◽  
S.J. Barnett
Keyword(s):  
High Resolution ◽  
The State ◽  
Epitaxial Layers ◽  
Misfit Dislocations ◽  
X Ray Diffraction ◽  
X Ray ◽  
Additional Information ◽  
Transmission Electron ◽  
Dislocation Densities

AbstractThe state of deformation in epitaxial layers of InGaAs grown by MBE on GaAs substrates has been determined using high resolution X-ray diffraction. This method enables the strains and rigid body rotations which occur in the layers to be measured and these are described by means of a tensor. Layers of different thicknesses have been grown on substrates whose dislocation densities differ by three orders of magnitude in order to assess the influence of this parameter on layer relaxation through the motion of misfit dislocations to the interface. Transmission electron microscopy has also been used to provide additional information on the relaxations.

Strain Relaxation in GaAs on Si by Two Groups of Misfit Dislocations

1995 ◽  
Vol 399 ◽  
Author(s):  
M. Tamura ◽  
T. Saitoh ◽  
T. Yodo
Keyword(s):  
Strain Relaxation ◽  
Lattice Misfit ◽  
Misfit Dislocations ◽  
Cross Sectional ◽  
Plan View ◽  
Partial Dislocations ◽  
Group I ◽  
Transmission Electron ◽  
Before And After ◽  
Gaas Films

ABSTRACTHigh-resolution cross-sectional and conventional plan-view transmission electron microscope observations have been carried out for molecular beam epitaxially grown GaAs films on vicinal Si (001) as a function of film thicknesses and observation directions between two orthogonal <110> directions before and after annealing. Two groups of misfit dislocations are characterized by analyzing whether their extra half planes exist in the film and the substrate side. The group I misfit dislocations due to a stress caused by a lattice misfit between GaAs and Si consist of partial and, 60° and 90° complete dislocations in an as-grown state. After annealing partial dislocations almost disappear and 90° perfect dislocations are predominantly observed. The group II misfit dislocations due to a thermal-expansion misfit-induced stress are all of the 60° type complete dislocations, independent of film thickness and annealing.

Defects in Large-Misfit Heteroepitaxy

1988 ◽  
Vol 116 ◽  
Author(s):  
D.J. Eaglesham ◽  
M. Aindow ◽  
R.C. Pond
Keyword(s):  
Substrate Surface ◽  
Threading Dislocations ◽  
Misfit Dislocations ◽  
Island Growth ◽  
Island Nucleation ◽  
Inversion Domain ◽  
Transmission Electron ◽  
Nucleation Mechanisms ◽  
Defect Nucleation ◽  
Inversion Domain Boundaries

AbstractA Transmission Electron Microscopy (TEM) study is presented of GaAs on Si (100) and CdTe on GaAs (100), and the implications for defect nucleation mechanisms are discussed. MOCVD GaAs/Si is shown to grow by island nucleation followed by 3D growth. Single islands are free of inversion domain boundaries (or “APBs”) implying that a single domain is able to grow over a demi-step on the substrate surface during this 3D growth. Misfit dislocations are shown to be edge type during island growth, with 60° type being generated at island junctions. The predominant threading dislocations are found to have inclined a/2 <110> Burgers vectors. The implied mechanisms for the generation of both misfit and threading dislocations are discussed. In MOCVD CdTe/GaAs the microstructure is shown to have a number of qualitatively similar features; in addition, study of this much larger misfit system allows us to deduce a possible explanation for misorientation effects in these systems.

Interfacial and twin boundary structures of nanostructured Cu–Ag filamentary composites

2003 ◽  
Vol 18 (9) ◽  
pp. 2194-2202 ◽  
Author(s):  
K. H. Lee ◽  
S. I. Hong
Keyword(s):  
Twin Boundary ◽  
Lattice Misfit ◽  
Longitudinal Section ◽  
Copper Matrix ◽  
Misfit Strain ◽  
Boundary Structure ◽  
Misfit Dislocations ◽  
Transmission Electron ◽  
The Matrix ◽  
Twinning Shear

A high-resolution transmission electron microscope was used to study the interfacial and twin boundary structure of nanostructured Cu–Ag filamentary composites. Copper matrix and silver filaments have the orientation relationship {111}Cu∥{111}Ag and 〈111〉Cu∥〈111〉Ag. In some regions, twin bands propagated through the silver filaments with some boundary steps at the matrix/filament interface, and the silver filament appeared to be kinked in the twin band in the same direction as the twinning shear. This suggests that twins propagated after the formation of silver filament, and twin bands were deformation twins. At the matrix/filament interface, misfit interface dislocations were introduced periodically to relieve the misfit strain. The distance between interfacial misfit dislocations along the matrix/filament interface in the longitudinal section was measured to be 1.88 nm, which is in good agreement with that (1.81 nm) calculated based on lattice misfit. In Cu–Ag nanocomposites, the spacing between Moire fringes was found to be quite close to that between interfacial misfit dislocations.

The Fine-Structure, Classification, and Orientation of Small Vapor-Deposited Metal Particles

1975 ◽  
Vol 33 ◽  
pp. 92-93
Author(s):  
Klaus Heinemann
Keyword(s):  
Bragg Reflection ◽  
Substrate Surface ◽  
Dark Field ◽  
Crystallographic Structure ◽  
Transmission Electron ◽  
Deposited Metal ◽  
Muscovite Mica ◽  
Lattice Planes ◽  
Substrate Surfaces ◽  
Multiply Twinned Particles

The crystallographic structure and overgrowth orientation of small gold particles vapor deposited onto vacuum cleaved muscovite mica and {100} LiF substrate surfaces were examined by regular and selected zone dark field (SZDF) transmission electron microscopy in connection with the Bragg reflection imaging (BRI) method. In the case of Au/LiF, only very few (less than 2% particles) were found which exhibited the characteristic triangular shape of single crystalline, {111} oriented overgrowth crystallites with {220} lattice planes as lowest index planes normal to the substrate surface (Fig. 1, particle F). All other particles could be classified as multiply twinned particles, more than 90% of them having a {111} oriented nucleus.

Preparation of wurtzitic AlN thin films with a novel crystallographic alignment on MgO substrates by molecular-beam epitaxy

1998 ◽  
Vol 13 (6) ◽  
pp. 1414-1417 ◽  
Author(s):  
J. R. Heffelfinger ◽  
D. L. Medlin ◽  
K. F. McCarty
Keyword(s):  
Electron Microscopy ◽  
Thin Films ◽  
Transmission Electron Microscopy ◽  
Molecular Beam Epitaxy ◽  
Molecular Beam ◽  
Substrate Surface ◽  
Transmission Electron ◽  
Aln Film

Thin films of wurtzitic AlN have been deposited by molecular-beam epitaxy onto (001) oriented MgO substrates. The films are epitactic and align with the and the , as evidenced by transmission electron microscopy. This configuration, which matches a close-packed direction of the film and substrate, allows for growth of two symmetrically equivalent orientation variants of the AlN film. These variants are distinguished by a 90° rotation about the direction that is normal to the substrate surface. Each variant also aligns the and the to within 5° of being parallel to the (200)MgO. The microstructure of the AlN films and origins of these novel alignments are discussed.

Metal-Oxide Interfacial Structures Produced By Internal Oxidation

1991 ◽  
Vol 238 ◽  
Author(s):  
P. Lu ◽  
I.-C. Tung ◽  
F. Cosandey
Keyword(s):  
Orientation Relationship ◽  
Internal Oxidation ◽  
Spinel Phase ◽  
Al Alloys ◽  
Misfit Dislocations ◽  
Cube Orientation ◽  
Transmission Electron ◽  
Interfacial Structures ◽  
Oxide Phases ◽  
Lattice Planes

ABSTRACTInterfaces in Cu/MgO, Pd/MgO, Pd/Al2O3, Ni/NiAl2O4 and Ni/Al2O3 systems produced by internal oxidation have been studied by transmission electron microscopy. For the Cu/MgO system, the MgO particles, with a cube-on-cube orientation with respect to Cu matrix, are faceted with principal faces parallel to {111} lattice planes of Cu and MgO. For the Pd/MgO system, the MgO particles, with a cube-on-cube orientation with Pd matrix, are faceted with interfaces parallel to the {100} and {111} lattice planes of MgO and Pd. Additional plate-like MgO particles with main facets parallel to {111} lattice planes possess a twin orientation relationship with the Pd matrix. Interfaces in Cu/MgO and Pd/MgO systems are all partially coherent with interfacial misfit dislocations. For the Pd/Al2O3 system, various transition oxide phases such as η, δ, and θ-Al2O3 and stable α-Al2O3 phase have been observed. The [1100] direction of α-Al2O3 is parallel to the [110] direction of Pd and the (0001) plane of α-Al2O3 is parallel or nearly parallel to the (110) plane of Pd. The NiAl2O4 spinel phase and Al2O3 phases are formed in Ni-Al alloys under two different oxidation conditions. The NiAl2O4 particles have a plate-like morphology with a cube-on-cube orientation relationship with the Ni matrix, while Al2O3 particles are randomly oriented.

scholarly journals Revisit the Role of Steps/Disconnections on Misfit Cancellation at Semi-Coherent Interface—Bridging the O-Line Model and the Topological Model

Crystals ◽  
2019 ◽  
Vol 9 (10) ◽  
pp. 525 ◽  
Author(s):  
Dong Qiu
Keyword(s):  
Coincidence Site Lattice ◽  
Lattice Misfit ◽  
Interface Structure ◽  
Current Approach ◽  
Topological Model ◽  
Misfit Dislocations ◽  
Line Model ◽  
Coherent Interface ◽  
Lattice Planes

It has been a long-standing topic how the lattice misfit is cancelled at a semi-coherent interphase boundary consisting of terraces and steps. Apart from a set of misfit dislocations separating the coherent patches, the role of steps (which is frequently called ‘disconnections’) on misfit cancellation remains ambiguous because these steps do not destroy the continuity of lattice planes across the interface. This paper aims to clarify such ambiguity through identification of a set of secondary dislocations through a rigorous constrained coincidence site lattice (CCSL)/constrained displacive shift complete lattice (CDSCL) analysis. A semi-coherent interface between body-centred cubic (BCC) Cr-rich precipitate and face-centred cubic (FCC) Cu-rich matrix that holds a near N-W orientation relationship (OR) is used as an example to demonstrate the procedure to determine the secondary dislocations that are coincident with steps along the interface. The current approach does not only redefine the disconnections in the topological model, but also extends the description of interface structure from the O-line model. As a result, the ‘discrepancy’ between these two popular crystallographic models can be completely eliminated when the interface is required to contain a pair of parallel close-packed directions.

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