Identification of Microdefects in Multicrystalline Silicon

1997 ◽  
Vol 469 ◽  
Author(s):  
M. Werner ◽  
H. J. Möller ◽  
E. Wolf
Keyword(s):  
Point Defects ◽  
Stacking Faults ◽  
Multicrystalline Silicon ◽  
Etch Pits ◽  
Qualitative Comparison ◽  
Amorphous Silicon Dioxide ◽  
Agglomeration Process ◽  
Transmission Electron ◽  
Different Types ◽  
Defects And Impurities

ABSTRACTMicrodefects in multicrystalline silicon grown by directional solidification have been investigated by transmission electron microscopy. Their density (=106 cm−2) correlates with the density of shallow etch pits observed after chemomechanical polishing and selective etching. Different types of microdefects (size 10 – 100 nm) could be identified: i) spherical precipitates most likely amorphous silicon dioxide, ii) small plates lying on {111} planes and iii) groups of closely spaced stacking faults having the character of dipoles. It is argued that these defects are the result of agglomeration process of intrinsic point defects and impurities, where oxygen and carbon are the main candidates. A qualitative comparison to the point defects agglomeration observed in Cz material will be given.

scholarly journals TEM Study of Defects in Laterally Overgrown GaN Layers

1999 ◽  
Vol 4 (S1) ◽  
pp. 459-464 ◽  
Author(s):  
Z. Liliental-Weber ◽  
M. Benamara ◽  
W. Swider ◽  
J. Washburn ◽  
J. Park ◽  
...  
Keyword(s):  
Electron Microscopy ◽  
Point Defects ◽  
Crystallographic Direction ◽  
Initial Growth ◽  
Lateral Growth ◽  
Planar Defects ◽  
Transmission Electron ◽  
Defects And Impurities ◽  
Two Sides ◽  
Line Direction

Transmission electron microscopy was applied to study defects in laterally overgrown GaN layers, with initial growth on Al2O3 substrates followed by further growth over SiO2 masks. Dislocations found in the overgrown areas show changes in line direction. Most dislocations propagate along c-planes. In the overgrown material planar defects (faulted loops) are present on c-planes and their presence is most probably related to segregation of excess point defects and impurities present in this material. They appear to be initiated by the fast lateral growth. Some dislocations with screw orientation become helical resulting from climb motion.Formation of voids and also a high dislocation density was observed at the boundaries where two overgrowing fronts meet. Tilt and twist components were observed for these boundaries that were different for different overgrown strips grown in the same crystallographic direction suggesting that the GaN subgrain orientations on the two sides of a SiO2 mask are responsible for the final tilt and twist value.

Manifestation of structural defects in photoluminescence from GaN

2003 ◽  
Vol 798 ◽  
Author(s):  
M. A. Reshchikov ◽  
J. Jasinski ◽  
F. Yun ◽  
L. He ◽  
Z. Liliental-Weber ◽  
...  
Keyword(s):  
Point Defects ◽  
Molecular Beam ◽  
Stacking Faults ◽  
Structural Defects ◽  
Large Set ◽  
X Ray Diffraction ◽  
Cross Sectional ◽  
X Ray ◽  
Transmission Electron ◽  
Gan Crystal

ABSTRACTSharp peaks of unidentified nature are detected in the low-temperature photoluminescence (PL) spectrum of undoped GaN in the photon energy range between 3.0 and 3.46 eV. These PL lines are commonly attributed to excitons bound to yet unidentified structural defects. We analyzed X-ray diffraction data in a large set of GaN samples grown by molecular beam epitaxy in order to find any correlation between these unusual PL peaks and the GaN crystal structure. Moreover, in selected samples exhibiting such peaks, cross-sectional transmission electron microscopy was taken in an effort to detect the presence and density of various structural defects. The preliminarily results indicate that most of unusual PL lines in GaN (Y lines) are not directly related to the observed structural defects, such as edge, screw, mixed dislocations, or stacking faults. However, there exists the possibility that point defects trapped at dislocations or other structural defects are responsible for these PL lines.

Defect clustering in GaN irradiated with O+ ions

2002 ◽  
Vol 17 (11) ◽  
pp. 2945-2952 ◽  
Author(s):  
C. M. Wang ◽  
W. Jiang ◽  
W. J. Weber ◽  
L. E. Thomas
Keyword(s):  
Point Defects ◽  
Basal Plane ◽  
Room Temperature ◽  
Dynamic Recovery ◽  
Stacking Faults ◽  
Extended Defects ◽  
Dislocation Loops ◽  
Defect Clusters ◽  
Transmission Electron ◽  
High Resolution Tem

Transmission electron microscopy (TEM) was used to study microstructures formed in GaN irradiated with 600-keV O+ ions at room temperature. Three types of defect clusters were identified in the irradiated GaN: (i) basal-plane stacking faults with dimensions ranging from 5 to 30 nm, (ii) pyramidal dislocation loops, and (iii) local regions of highly disordered material. High-resolution TEM imaging clearly revealed that one type of the basal-plane stacking faults corresponded to insertion of one extra Ga–N basal plane in the otherwise perfect GaN lattice. The interpretation of these results indicated that interstitials of both Ga and N preferentially condensed on the basal plane to form a new layer of Ga–N under these irradiation conditions. The formation of these extended defects and their interactions with the point defects produced during irradiation contributed to a dramatic increase in the dynamic recovery of point defects in GaN at room temperature.

Tem Study of Defects in Laterally Overgrown GaN Layers

1998 ◽  
Vol 537 ◽  
Author(s):  
Z. Liliental-Weber ◽  
M. Benamara ◽  
W. Swider ◽  
J. Washburn ◽  
J. Park ◽  
...  
Keyword(s):  
Electron Microscopy ◽  
Point Defects ◽  
Crystallographic Direction ◽  
Initial Growth ◽  
Lateral Growth ◽  
Planar Defects ◽  
Transmission Electron ◽  
Defects And Impurities ◽  
Two Sides ◽  
Line Direction

AbstractTransmission electron microscopy was applied to study defects in laterally overgrown GaN layers, with initial growth on A12O3 substrates followed by further growth over SiO2 masks. Dislocations found in the overgrown areas show changes in line direction. Most dislocations propagate along c-planes. In the overgrown material planar defects (faulted loops) are present on c-planes and their presence is most probably related to segregation of excess point defects and impurities present in this material. They appear to be initiated by the fast lateral growth. Some dislocations with screw orientation become helical resulting from climb motion.Formation of voids and also a high dislocation density was observed at the boundaries where two overgrowing fronts meet. Tilt and twist components were observed for these boundaries that were different for different overgrown strips grown in the same crystallographic direction suggesting that the GaN subgrain orientations on the two sides of a SiO2 mask are responsible for the final tilt and twist value.

The Defect Structures of Fe9S10

1983 ◽  
Vol 31 ◽  
Author(s):  
Thao A. Nguyen ◽  
Linn W. Hobbs
Keyword(s):  
Electron Microscopy ◽  
Transmission Electron Microscopy ◽  
Stacking Faults ◽  
Defect Structures ◽  
Transmission Electron ◽  
Vacancy Ordering ◽  
Different Types ◽  
Lattice Images ◽  
Antiphase Domains ◽  
Complex Features

ABSTRACTThe defect structures of Fe9S10 have been studied by high-resolution transmission electron microscopy. Lattice images of the 3C and 4C superstructures and at least one other phase, which has not been previously reported, were observed. It has been found that the 4C superstructure transforms into the 3C superstructure rather than the MC phase as previously suggested. Intrinsic stacking faults in the sulfur sublattice and two different types of vacancy-ordering antiphase domains were also observed. Evidence from optical diffratograms of areas containing these defects suggests that complex features in the electron diffraction pattern may be artifactual.

Study of dislocation loops in Arsenic-Rich as-grown GaAs

1987 ◽  
Vol 45 ◽  
pp. 350-351
Author(s):  
Byung-Teak Lee
Keyword(s):  
Point Defects ◽  
Electronic Devices ◽  
Arsenic Concentration ◽  
Stoichiometric Compound ◽  
Dislocation Loops ◽  
Gaas Crystal ◽  
Ion Milling ◽  
Transmission Electron ◽  
Arsenic Source ◽  
High Arsenic

Grown-in dislocations in GaAs have been a major obstacle in utilizing this material for the potential electronic devices. Although it has been proposed in many reports that supersaturation of point defects can generate dislocation loops in growing crystals and can be a main formation mechanism of grown-in dislocations, there are very few reports on either the observation or the structural analysis of the stoichiometry-generated loops. In this work, dislocation loops in an arsenic-rich GaAs crystal have been studied by transmission electron microscopy.The single crystal with high arsenic concentration was grown using the Horizontal Bridgman method. The arsenic source temperature during the crystal growth was about 630°C whereas 617±1°C is normally believed to be optimum one to grow a stoichiometric compound. Samples with various orientations were prepared either by chemical thinning or ion milling and examined in both a JEOL JEM 200CX and a Siemens Elmiskop 102.

Structure of stacking faults in pyrite using TEM techniques

1992 ◽  
Vol 50 (1) ◽  
pp. 358-359
Author(s):  
Raja Subramanian ◽  
Kenneth S. Vecchio
Keyword(s):  
Lattice Structure ◽  
Stacking Faults ◽  
Covalent Bond ◽  
Group Symmetry ◽  
Iron Pyrite ◽  
Dislocation Glide ◽  
Partial Dislocations ◽  
Transmission Electron ◽  
Contrast Analysis ◽  
Chlorine Ions

The structure of stacking faults and partial dislocations in iron pyrite (FeS2) have been studied using transmission electron microscopy. Pyrite has the NaCl structure in which the sodium ions are replaced by iron and chlorine ions by covalently-bonded pairs of sulfur ions. These sulfur pairs are oriented along the <111> direction. This covalent bond between sulfur atoms is the strongest bond in pyrite with Pa3 space group symmetry. These sulfur pairs are believed to move as a whole during dislocation glide. The lattice structure across these stacking faults is of interest as the presence of these stacking faults has been preliminarily linked to a higher sulfur reactivity in pyrite. Conventional TEM contrast analysis and high resolution lattice imaging of the faulted area in the TEM specimen has been carried out.

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.

Flux-pinning-related defect structures in melt-processed YBa2Cu3O7-x

1993 ◽  
Vol 51 ◽  
pp. 936-937
Author(s):  
Z. L. Wang ◽  
R. Kontra ◽  
A. Goyal ◽  
D. M. Kroeger ◽  
L.F. Allard
Keyword(s):  
Volume Fraction ◽  
Local Density ◽  
Stacking Faults ◽  
Image Resolution ◽  
Defect Structures ◽  
Atomic Structures ◽  
Transmission Electron ◽  
Point Image ◽  
Related Defect ◽  
Point To Point

Previous studies of Y2BaCuO5/YBa2Cu3O7-δ(Y211/Y123) interfaces in melt-processed and quench-melt-growth processed YBa2Cu3O7-δ using high resolution transmission electron microscopy (HRTEM) and energy dispersive X-ray spectroscopy (EDS) have revealed a high local density of stacking faults in Y123, near the Y211/Y123 interfaces. Calculations made using simple energy considerations suggested that these stacking faults may act as effective flux-pinners and may explain the observations of increased Jc with increasing volume fraction of Y211. The present paper is intended to determine the atomic structures of the observed defects. HRTEM imaging was performed using a Philips CM30 (300 kV) TEM with a point-to-point image resolution of 2.3 Å. Nano-probe EDS analysis was performed using a Philips EM400 TEM/STEM (100 kV) equipped with a field emission gun (FEG), which generated an electron probe of less than 20 Å in diameter.Stacking faults produced by excess single Cu-O layers: Figure 1 shows a HRTEM image of a Y123 film viewed along [100] (or [010]).

scholarly journals The impact of point defects in n-type GaN layers on thermal decomposition of InGaN/GaN QWs

2021 ◽  
Vol 11 (1) ◽  
Author(s):  
Mikolaj Grabowski ◽  
Ewa Grzanka ◽  
Szymon Grzanka ◽  
Artur Lachowski ◽  
Julita Smalc-Koziorowska ◽  
...  
Keyword(s):  
Quantum Wells ◽  
High Temperatures ◽  
Point Defects ◽  
X Ray Diffraction ◽  
Helium Ions ◽  
X Ray ◽  
Sapphire Substrates ◽  
Transmission Electron ◽  
The Impact ◽  
Ingan Quantum Wells

AbstractThe aim of this paper is to give an experimental evidence that point defects (most probably gallium vacancies) induce decomposition of InGaN quantum wells (QWs) at high temperatures. In the experiment performed, we implanted GaN:Si/sapphire substrates with helium ions in order to introduce a high density of point defects. Then, we grew InGaN QWs on such substrates at temperature of 730 °C, what caused elimination of most (but not all) of the implantation-induced point defects expanding the crystal lattice. The InGaN QWs were almost identical to those grown on unimplanted GaN substrates. In the next step of the experiment, we annealed samples grown on unimplanted and implanted GaN at temperatures of 900 °C, 920 °C and 940 °C for half an hour. The samples were examined using Photoluminescence, X-ray Diffraction and Transmission Electron Microscopy. We found out that the decomposition of InGaN QWs started at lower temperatures for the samples grown on the implanted GaN substrates what provides a strong experimental support that point defects play important role in InGaN decomposition at high temperatures.

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