Generation of misfit dislocations by basal-plane slip in InGaN∕GaN heterostructures

2006 ◽  
Vol 89 (20) ◽  
pp. 201911 ◽  
Author(s):  
R. Liu ◽  
J. Mei ◽  
S. Srinivasan ◽  
F. A. Ponce ◽  
H. Omiya ◽  
...  
Keyword(s):  
Basal Plane ◽  
Misfit Dislocations

Threading Dislocation Density Reduction in GaN/Sapphire Heterostructures.

1999 ◽  
Vol 595 ◽  
Author(s):  
A. Kvit ◽  
A. K. Sharma ◽  
J. Narayan
Keyword(s):  
Basal Plane ◽  
Stacking Faults ◽  
High Density ◽  
Thin Layers ◽  
Interfacial Region ◽  
Threading Dislocation ◽  
Threading Dislocations ◽  
Misfit Dislocations ◽  
Plan View ◽  
Partial Dislocations

AbstractLarge lattice mismatch between GaN and α-Al2O3 (15%) leads to the possibility of high threading dislocation densities in the nitride layers grown on sapphire. This investigation focused on defect reduction in GaN epitaxial thin layer was investigated as a function of processing variables. The microstructure changes from threading dislocations normal to the basal plane to stacking faults in the basal plane. The plan-view TEM and the corresponding selected-area diffraction patterns show that the film is single crystal and is aligned with a fixed epitaxial orientation to the substrate. The epitaxial relationship was found to be (0001)GaN∥(0001)Sap and [01-10]GaN∥[-12-10]Sap. This is equivalent to a 30° rotation in the basal (0001) plane. The film is found to contain a high density of stacking faults with average spacing 15 nm terminated by partial dislocations. The density of partial dislocations was estimated from plan-view TEM image to be 7×109 cm−2. The cross-section image of GaN film shows the density of stacking faults is highest in the vicinity of the interface and decreases markedly near the top of the layer. Inverted domain boundaries, which are almost perpendicular to the film surface, are also visible. The concentration of threading dislocation is relatively low (∼;2×108 cm−2), compared to misfit dislocations. The average distance between misfit dislocations was found to be 22 Å. Contrast modulations due to the strain near misfit dislocations are seen in high-resolution cross-sectional TCM micrograph of GaN/α-Al2O3 interface. This interface is sharp and does not contain any transitional layer. The interfacial region has a high density of Shockley and Frank partial dislocations. Mechanism of accommodation of tensile, sequence and tilt disorder through partial dislocation generation is discussed. In order to achieve low concentration of threading dislocations we need to establish favorable conditions for some stacking disorder in thin layers above the film-substrate interface region.

Misfit Dislocations in the Interface between the Metallic and Insulating Phases in Cr Doped V203

1983 ◽  
Vol 31 ◽  
Author(s):  
Nobuo Otsuka ◽  
Hiroshi Sato
Keyword(s):  
Basal Plane ◽  
Room Temperature ◽  
Misfit Dislocations ◽  
Weak Beam ◽  
Principal Axes ◽  
Beam Technique

ABSTRACTThe formation of misfit dislocations in the interface between the metallic and insulating phases which occur in 1.2% Cr doped V203 near room temperature was confirmed by TEM. Orientations of Burgers vectors of misfit dislocations were determined by the weak beam technique. The Burger vectors were parallel to principal axes in the basal plane (<100>) and inclined somewhat to interfaces. The Burgers vectors of misfit dislocations are, however, close enough to the direction of the maximum misfit in the interface. Only one or two misfit dislocations appear in an interface regardless of the thickness of specimens, and these were always located near the surface.

Basal plane misfit dislocations and stress relaxation in III-nitride semipolar heteroepitaxy

2011 ◽  
Vol 109 (10) ◽  
pp. 103522 ◽  
Author(s):  
Alexey E. Romanov ◽  
Erin C. Young ◽  
Feng Wu ◽  
Anurag Tyagi ◽  
Chad S. Gallinat ◽  
...  
Keyword(s):  
Stress Relaxation ◽  
Basal Plane ◽  
Misfit Dislocations

Intersecting basal plane and prismatic stacking fault structures and their formation mechanisms in GaN

2005 ◽  
Vol 892 ◽  
Author(s):  
Jie Bai ◽  
X. Huang ◽  
M. Dudley
Keyword(s):  
Basal Plane ◽  
Lattice Mismatch ◽  
Strain Relaxation ◽  
Stacking Faults ◽  
Stacking Fault ◽  
Formation Mechanisms ◽  
Misfit Dislocations ◽  
Aln Film ◽  
Film Forming ◽  
Fault Structures

AbstractComparative TEM studies have been carried out on GaN/AlN epifilms grown on both on-axis and off-cut 6H-SiC substrates to study the defects formed in the GaN/AlN films and the state of strain relaxation at the interface. Prismatic Stacking Faults (PSFs) are observed to form at I1 type substrate steps in both the on-axis and vicinal samples. In the vicinal samples, the PSFs expand into GaN/AlN film forming intersecting stacking fault configurations comprising faults that fold back and forth from the basal plane (I1 Basal-Plane Stacking Faults; BSFs) to the prismatic plane (PSFs). On the other hand, in the on-axis sample the PSFs are observed to mostly annihilate each other to form enclosed domains confined to the near-interface region. In addition, HRTEM studies suggest the existence of Geometric Partial Misfit Dislocations (GPMDs) at the SiC/AlN interface of the vicinal sample, which form at I2 type substrate steps. These GPMDs simultaneously accommodate the lattice mismatch and stacking sequence mismatch present at the SiC/AlN interface. This provides explanation of the improved strain relaxation observed in the vicinal versus the on-axis sample.

Observation of Misfit Dislocations Introduced by Epi-Layer Growth on 4H-SiC

2008 ◽  
Vol 600-603 ◽  
pp. 309-312 ◽  
Author(s):  
Hirofumi Matsuhata ◽  
Hirotaka Yamaguchi ◽  
Ichiro Nagai ◽  
Toshiyuki Ohno ◽  
Ryouji Kosugi ◽  
...  
Keyword(s):  
Basal Plane ◽  
Grazing Incidence ◽  
Lattice Parameter ◽  
Layer Growth ◽  
Misfit Dislocations ◽  
Screw Dislocations ◽  
Incidence Geometries ◽  
The Difference ◽  
Edge Dislocations ◽  
Monochromatic Synchrotron

4H-SiC substrate wafers with epi-layers were observed using monochromatic synchrotron X-ray topography in grazing incidence geometries, to investigate the defects in the epi-layer. Misfit dislocations with b=+1/3[11 2 0] caused by the difference in lattice parameter between the epi-layer and the substrate were observed. The misfit dislocations are located near the interface as edge dislocations, and appear at the top surface as screw dislocations on basal planes. It was observed that more than half of them were introduced from the growing epi-layer surface. The misfit dislocations and some screw dislocations with b=+1/3[11 2 0] are observed to remain as basal plane dislocations at the surface, while other basal plane dislocations were converted to threading edge dislocations in the epi-layer.

Structural aspects of silicon diffusion in quaternary III-V thin-film semiconductors

1991 ◽  
Vol 49 ◽  
pp. 850-851
Author(s):  
F. A. Ponce ◽  
R. L. Thornton ◽  
G. B. Anderson
Keyword(s):  
Semiconductor Lasers ◽  
Wide Bandgap ◽  
Semiconductor Diode ◽  
Visible Range ◽  
P System ◽  
Misfit Dislocations ◽  
Lattice Match ◽  
Semiconductor Diode Laser ◽  
Thin Film Semiconductors ◽  
Silicon Diffusion

The InGaAlP quaternary system allows the production of semiconductor lasers emitting light in the visible range of the spectrum. Recent advances in the visible semiconductor diode laser art have established the viability of diode structures with emission wavelengths comparable to the He-Ne gas laser. There has been much interest in the growth of wide bandgap quaternary thin films on GaAs, a substrate most commonly used in optoelectronic applications. There is particular interest in compositions which are lattice matched to GaAs, thus avoiding misfit dislocations which can be detrimental to the lifetime of these materials. As observed in Figure 1, the (AlxGa1-x)0.5In0.5P system has a very close lattice match to GaAs and is favored for these applications.In this work, we have studied the effect of silicon diffusion in GaAs/InGaAlP structures. Silicon diffusion in III-V semiconductor alloys has been found to have an disordering effect which is associated with removal of fine structures introduced during growth. Due to the variety of species available for interdiffusion, the disordering effect of silicon can have severe consequences on the lattice match at GaAs/InGaAlP interfaces.

Observations of the Thermal Decomposition of Brucite

1968 ◽  
Vol 26 ◽  
pp. 446-447
Author(s):  
P. L. Burnett ◽  
W. R. Mitchell ◽  
C. L. Houck
Keyword(s):  
Thermal Decomposition ◽  
Magnesium Oxide ◽  
Basal Plane ◽  
Magnesium Ions ◽  
A Value ◽  
Reaction Proceeds

Natural Brucite (Mg(OH)2) decomposes on heating to form magnesium oxide (MgO) having its cubic ﹛110﹜ and ﹛111﹜ planes respectively parallel to the prism and basal planes of the hexagonal brucite lattice. Although the crystal-lographic relation between the parent brucite crystal and the resulting mag-nesium oxide crystallites is well known, the exact mechanism by which the reaction proceeds is still a matter of controversy. Goodman described the decomposition as an initial shrinkage in the brucite basal plane allowing magnesium ions to shift their original sites to the required magnesium oxide positions followed by a collapse of the planes along the original <0001> direction of the brucite crystal. He noted that the (110) diffraction spots of brucite immediately shifted to the positions required for the (220) reflections of magnesium oxide. Gordon observed separate diffraction spots for the (110) brucite and (220) magnesium oxide planes. The positions of the (110) and (100) brucite never changed but only diminished in intensity while the (220) planes of magnesium shifted from a value larger than the listed ASTM d spacing to the predicted value as the decomposition progressed.

In situ TEM measurements of the electrical properties of interface dislocations

1992 ◽  
Vol 50 (2) ◽  
pp. 1338-1339
Author(s):  
F. M. Ross ◽  
R. Hull ◽  
D. Bahnck ◽  
J. C. Bean ◽  
L. J. Peticolas ◽  
...  
Keyword(s):  
Electrical Properties ◽  
Electronic Device ◽  
In Situ Tem ◽  
Device Performance ◽  
Misfit Dislocations ◽  
Electrical Characteristics ◽  
Strained Layer ◽  
Transmission Electron ◽  
Interfacial Dislocations

We describe an investigation of the electrical properties of interfacial dislocations in strained layer heterostructures. We have been measuring both the structural and electrical characteristics of strained layer p-n junction diodes simultaneously in a transmission electron microscope, enabling us to correlate changes in the electrical characteristics of a device with the formation of dislocations.The presence of dislocations within an electronic device is known to degrade the device performance. This degradation is of increasing significance in the design and processing of novel strained layer devices which may require layer thicknesses above the critical thickness (hc), where it is energetically favourable for the layers to relax by the formation of misfit dislocations at the strained interfaces. In order to quantify how device performance is affected when relaxation occurs we have therefore been investigating the electrical properties of dislocations at the p-n junction in Si/GeSi diodes.

Growth of spinel into alumina

1987 ◽  
Vol 45 ◽  
pp. 294-295
Author(s):  
Y. Kouh Simpson ◽  
C. B. Carter
Keyword(s):  
Misfit Dislocations ◽  
Phase Boundaries ◽  
Large Rotation ◽  
Alumina Phase ◽  
Metallic Interfaces ◽  
Small Rotation

The structure of spinel/alumina phase boundaries has recently been studied using the selected- area diffraction technique. It has been found that there exist several dominant topotactic relationships; of these, the two most common situations are when the {111} plane of spinel is parallel to either the (0001) plane or the {1120} plane of alumina. In both of these cases, it has been found that there is often a small rotation from exact topotaxy (typically 0° to 2° but with larger rotations possible) which partially eliminates the need for misfit dislocations. This rotation is a special phenomenon that may be unique to non-metallic interfaces such as phase boundaries in ceramics. In this report, a special spinel/alumina interface in which a large rotation from the exact topotaxy exists between the (111) plane of spinel and the (OOOl) plane of alumina is discussed.

Atomic structure of stair rod misfit dislocations at the GaAs on Si(100) interface

1990 ◽  
Vol 48 (4) ◽  
pp. 342-343
Author(s):  
D. Gerthsen
Keyword(s):  
Lattice Constant ◽  
Atomic Structure ◽  
Spherical Aberration ◽  
Stacking Faults ◽  
Misfit Dislocations ◽  
Gaas On Si ◽  
Thermal Expansion Coefficients ◽  
Transmission Electron ◽  
Intersection Line ◽  
Oriented Parallel

The prospect of technical applications has induced a lot of interest in the atomic structure of the GaAs on Si(100) interface and the defects in its vicinity which are often studied by high resolution transmission electron microscopy. The interface structure is determined by the 4.1% lattice constant mismatch between GaAs and Si, the large difference between the thermal expansion coefficients and the polar/nonpolar nature of the GaAs on Si interface. The lattice constant mismatch is compensated by misfit dislocations which are characterized by a/2<110> Burgers vectors b which are oriented parallel or inclined on {111} planes with respect to the interface. Stacking faults are also frequently observed. They are terminated by partial dislocations with b = a/6<112> on {111} planes. In this report, the atomic structure of stair rod misfit dislocations is analysed which are located at the intersection line of two stacking faults at the interface.A very thin, discontinous film of GaAs has been grown by MBE on a Si(100) substrate. Fig.1.a. shows an interface section of a 27 nm wide GaAs island along [110] containing a stair rod dislocation. The image has been taken with a JEOL 2000EX with a spherical aberration constant Cs = 1 mm, a spread of focus Δz = 10 nm and an angle of beam convergence ϑ of 2 mrad.

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