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.

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.

Scanning Transmission Electron Microscopy of Polyethylene Crystals

1980 ◽  
Vol 38 ◽  
pp. 242-245
Author(s):  
F. Khoury ◽  
L. H. Bolz
Keyword(s):  
Electron Microscopy ◽  
Transmission Electron Microscopy ◽  
Crystallization Temperature ◽  
Scanning Transmission Electron Microscopy ◽  
Growth Habit ◽  
Lateral Growth ◽  
Scanning Transmission Electron ◽  
Transmission Electron ◽  
Scanning Transmission ◽  
Growth Habits

The lateral growth habits and non-planar conformations of polyethylene crystals grown from dilute solutions (<0.1% wt./vol.) are known to vary depending on the crystallization temperature.1-3 With the notable exception of a study by Keith2, most previous studies have been limited to crystals grown at <95°C. The trend in the change of the lateral growth habit of the crystals with increasing crystallization temperature (other factors remaining equal, i.e. polymer mol. wt. and concentration, solvent) is illustrated in Fig.l. The lateral growth faces in the lozenge shaped type of crystal (Fig.la) which is formed at lower temperatures are {110}. Crystals formed at higher temperatures exhibit 'truncated' profiles (Figs. lb,c) and are bound laterally by (110) and (200} growth faces. In addition, the shape of the latter crystals is all the more truncated (Fig.lc), and hence all the more elongated parallel to the b-axis, the higher the crystallization temperature.

Structure of vacuum-deposited Zn3P2 films

1986 ◽  
Vol 64 (10) ◽  
pp. 1369-1373 ◽  
Author(s):  
U. von Sacken ◽  
D. E. Brodie
Keyword(s):  
Electron Microscopy ◽  
Transmission Electron Microscopy ◽  
Film Thickness ◽  
Substrate Temperature ◽  
Columnar Structure ◽  
Major Effect ◽  
Film Structure ◽  
Electron Bombardment ◽  
Initial Growth ◽  
Transmission Electron

The structure of polycrystalline Zn3P2 films has been studied for 1- to 2-μm-thick vacuum-deposited films on glass substrates. Transmission electron microscopy and X-ray diffraction techniques have been used to obtain a detailed, quantitative analysis of the film structure. The initial growth consists of small (≤ 10 nm), randomly oriented grains. As the film thickness increases, the growth of crystallites with the {220} planes oriented approximately parallel to the substrate is favoured, and a columnar structure develops along with a highly preferred orientation. This structure has been observed directly by transmission electron microscopy of thin cross sections of the films. The size of the grains at the free surface increases with the film thickness, reaching approximately 200–300 nm when the film is 1 μm thick. The effects of substrate temperature and low-energy (0.5–2 keV) electron bombardment of the film during growth have also been studied. Neither substrate temperature nor electron bombardment appear to have a major effect on the film structure. The primary effect of electron bombardment appears to be the creation of preferred nucleation sites on the substrate.

Defects in Germanium Nanocrystals Produced by Ion Implantation

2013 ◽  
Vol 709 ◽  
pp. 148-152
Author(s):  
Yu Juan Zhang ◽  
Lei Shang
Keyword(s):  
Electron Microscopy ◽  
Light Emission ◽  
Stacking Faults ◽  
Implantation Dose ◽  
Defect Structures ◽  
High Temperature Annealing ◽  
Planar Defects ◽  
Transmission Electron ◽  
Microstructural Defects ◽  
Germanium Nanocrystals

Germanium nanocrystals (Ge-nc) were produced by the implantation of Ge+ into a SiO2 film deposited on (100) Si, followed by a high-temperature annealing. High-resolution transmission electron microscopy (HRTEM) has been used to investigate the defect structures inside the Ge-nc produced by different implantation doses (1×1016, 2×1016, 4×1016 and 8×1016 cm-2). It has been found that the planar defects such as nanotwins and stacking faults (SFs) are dominant in Ge-nc (60%) for the samples with implantation doses higher than 2×1016 cm-2, while for the sample with an implantation dose lower than 1×1016 cm-2, fewer planar defects are observed in the Ge-nc (20%). The percentages of nanotwins in the planar defects are 87%, 77%, 67% and 60% in four samples, respectively. The twinning structures include single twins, double twins and multiple twins. We also found that there are only SFs in some nanocrystals, and in others the SFs coexist with twins. These microstructural defects are expected to play an important role in the light emission from the Ge-nc.

scholarly journals Thermal Annealing of High Dose P Implantation in 4H-SiC

2019 ◽  
Vol 963 ◽  
pp. 399-402 ◽  
Author(s):  
Cristiano Calabretta ◽  
Massimo Zimbone ◽  
Eric G. Barbagiovanni ◽  
Simona Boninelli ◽  
Nicolò Piluso ◽  
...  
Keyword(s):  
Electron Microscopy ◽  
Transmission Electron Microscopy ◽  
Raman Spectroscopy ◽  
Ion Implantation ◽  
Epitaxial Layer ◽  
Point Defects ◽  
High Dose ◽  
Double Step ◽  
Post Annealing ◽  
Transmission Electron

In this work, we have studied the crystal defectiveness and doping activation subsequent to ion implantation and post-annealing by using various techniques including photoluminescence (PL), Raman spectroscopy and transmission electron microscopy (TEM). The aim of this work was to test the effectiveness of double step annealing to reduce the density of point defects generated during the annealing of a P implanted 4H-SiC epitaxial layer. The outcome of this work evidences that neither the first 1 hour isochronal annealing at 1650 - 1700 - 1750 °C, nor the second one at 1500 °C for times between 4 hour and 14 hour were able to recover a satisfactory crystallinity of the sample and achieve dopant activations exceeding 1%.

Identification of Growth Induced Planar Defects in Silicon

1985 ◽  
Vol 62 ◽  
Author(s):  
H. P. Strunk ◽  
A. Kessler ◽  
E. Bauser
Keyword(s):  
Electron Microscopy ◽  
Transmission Electron Microscopy ◽  
Crystal Growth ◽  
Epitaxial Layers ◽  
Growth Interface ◽  
Fringe Contrast ◽  
Planar Defects ◽  
Transmission Electron ◽  
Contrast Analysis ◽  
Preferential Incorporation

ABSTRACTPlanar defects have been detected by transmission electron microscopy in silicon epitaxial layers that have been grown from Ga solutions below 500 °C. According to fringe contrast analysis, this defect can be modelled by a plane of Ga atoms within the Si lattice. This plane forms during crystal growth due to local preferential incorporation of Ga atoms at crystallographically defined sites, that occur repetitively in the trains of monomolecular growth steps at the liquid/solid growth interface.

Structural and Chemical Properties of MBE Grown Niobium Overlayers on (110) Rutile

1996 ◽  
Vol 441 ◽  
Author(s):  
J. Marien ◽  
T. Wagner ◽  
M. Rühle
Keyword(s):  
Electron Microscopy ◽  
Transmission Electron Microscopy ◽  
Defect Structure ◽  
Chemical Properties ◽  
High Energy ◽  
Initial Growth ◽  
High Energy Electron ◽  
Transmission Electron ◽  
Different Temperatures ◽  
And Chemical Properties

AbstractThin Nb films were grown by MBE in a UHV chamber at two different temperatures (50°C and 950°C) on the (110) surface of TiO2 (rutile).At a growth temperature of 50°C, reflection high energy electron diffraction (RHEED) revealed epitaxial growth of Nb on rutile: (110)[001] TiO2 ¦¦ (100)[001] Nb. In addition, investigations with Auger electron spectroscopy (AES) revealed that a chemical reaction took place between the Nb overlayer and the TiO2 substrate at the initial growth stage. A 2 nm thick reaction layer at the Nb/TiO2 interface has been identified by means of conventional transmission electron microscopy (CTEM) and high-resolution transmission electron microscopy (HRTEM).At a substrate temperature of 950°C, during growth, the Nb film was oxidized completely, and NbO2 grew epitaxially on TiO2. The structure and the chemical composition of the overlayers have been investigated by RHEED, AES, CTEM and HRTEM. Furthermore, it was determined that the reaction of Nb with TiO2 is governed by the defect structure of the TiO2 and the relative oxygen affinities of Nb and TiO2.

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