Influence of Antimony Doping on Nanoscale Arsenic Clusters and Dislocation Loops in Low-Temperature Grown Gallium Arsenide Films

2000 ◽  
Vol 652 ◽  
Author(s):  
V.V. Chaldyshev ◽  
N.A. Bert ◽  
A.E. Romanov ◽  
A.A. Suvorova ◽  
A.L. Kolesnikova ◽  
...  
Keyword(s):  
Electron Microscopy ◽  
Low Temperature ◽  
Molecular Beam ◽  
Dislocation Loops ◽  
Gaas Matrix ◽  
Transmission Electron ◽  
Antimony Doping ◽  
Gaas Films ◽  
Sb Doping ◽  
Ripening Rate

ABSTRACTTransmission electron microscopy was employed to study the microstructure of GaAs films grown by molecular-beam epitaxy at low temperature and delta-doped with Sb. Thus obtained material contained 0.5 at.% of excess arsenic that precipitates upon post-growth anneals. The Sb doping was found to strongly affect the microstructure of arsenic clusters and their ripening rate upon annealing. Segregation of Sb impurities in the As clusters was revealed. In contrast to the well known pure As clusters, the As-Sb clusters induced strong local deformations in the surrounding GaAs matrix. Relaxation of these deformations resulted in formation of dislocation loops, which was studied both experimentally and theoretically.

Tem Study of the Structure of Mbe GaAs Layers Grown at Low Temperature

1990 ◽  
Vol 198 ◽  
Author(s):  
Zuzanna Liliental-Weber
Keyword(s):  
Electron Microscopy ◽  
Low Temperature ◽  
Molecular Beam ◽  
Critical Thickness ◽  
Stacking Faults ◽  
Structural Quality ◽  
Crystalline Perfection ◽  
Transmission Electron ◽  
Low Temperature Gaas

ABSTRACTThe structural quality of GaAs layers grown at 200°C by molecular beam epitaxy (MBE) was investigated by transmission electron microscopy (TEM). We found that a high crystalline perfection can be achieved in the layers grown at this low temperature for thickness up to 3 μm. In some samples we observed pyramid-shaped defects with polycrystalline cores surrounded by microtwins, stacking faults and dislocations. The size of these cores increased as the growth temperature was decreased and as the layer thickness was increased. The upper surface of layers with pyramidal defects became polycrystalline at a critical thickness of the order of 3μm. We suggested that the low-temperature GaAs becomes polycrystalline at a critical thickness either because of a decrease in substrate temperature during growth or because strain induced by excess As incorporated in these layers leads to the formation of misoriented GaAs nuclei, thereby initiating polycrystalline growth. The pyramidal shape of the defects results from a growth-rate hierarchy of the low index planes in GaAs.

Strain-Field Induced Crosshatch Formation During Molecular Beam Epitaxy of InGaAs/GaAs Films

1993 ◽  
Vol 312 ◽  
Author(s):  
X. C. Zhou ◽  
J. Jiang ◽  
A. Y. Du ◽  
J. W. Zhao ◽  
S. M. Mu ◽  
...  
Keyword(s):  
Electron Microscopy ◽  
Molecular Beam Epitaxy ◽  
Molecular Beam ◽  
Direct Evidence ◽  
Surface Strain ◽  
Misfit Dislocations ◽  
Strain Fields ◽  
Transmission Electron ◽  
Gaas Films ◽  
Reflection Electron Microscopy

AbstractUsing reflection electron microscopy (REM), transmission electron microscopy (TEM), and Nomarski optical microscopy we obtained direct evidence that local surface strain-fields, originated from misfit dislocations, are responsible for the formation of morphological crosshatches during molecular beam epitaxy of lattice mismatched InGaAs/GaAs layers. A mechanism is proposed to correlate the formation of the crosshatched patterns with the variation of the growth rate across the epitaxial surface under the perturbation of network shaped strain-fields in the surface.

Heteroepitaxial Growth of High Quality GaAs Films on Rapid-Thermal-anealing Processed CaF2/Si(511) Structures

1988 ◽  
Vol 144 ◽  
Author(s):  
Tanemasa Asano ◽  
Hiroshi Ishiwara ◽  
Seijiro Furukawa
Keyword(s):  
Electron Microscopy ◽  
Molecular Beam ◽  
Crystalline Quality ◽  
Heteroepitaxial Growth ◽  
High Quality ◽  
Ion Channeling ◽  
Surface Steps ◽  
Transmission Electron ◽  
Good Crystalline Quality ◽  
Gaas Films

ABSTRACTHeteroepitaxial growth of CaF2 films on (511)Si and GaAs films on CaF2/Si(511) structures is investigated. CaF2 films and GaAs films are grown by vacuum evaporation and molecular beam epitaxy, respectively. Ion channeling measurements and replica transmission electron microscopy show that CaF2 films having good crystalline quality and surface steps can be formed by annealing at 900°C for 30 sec after the growth at 550° C. GaAs films having smooth surfaces and good crystalline quality can be grown on the annealed CaF2/Si(511) structures.

Structural Characterization of Low-Temperature InN Buffer Layer Grown by RF-MBE

2003 ◽  
Vol 798 ◽  
Author(s):  
T. Araki ◽  
Y. Nanishi
Keyword(s):  
Electron Microscopy ◽  
Transmission Electron Microscopy ◽  
Low Temperature ◽  
Buffer Layer ◽  
Molecular Beam ◽  
Cubic Phase ◽  
Local Fluctuations ◽  
Transmission Electron ◽  
Surface Migration

ABSTRACTThe microstructure of an InN buffer layer grown on (0001) sapphire at low temperature by radio-frequency molecular beam epitaxy (RF-MBE) is characterized by transmission electron microscopy. The low-temperature InN buffer layer is found to contain local inhomogeneous regions of island-like grains surrounded by misoriented InN grains and inclusions of cubic phase. The generation of such anti-phase InN nuclei near the island-like grains is expected to give rise to defects at the interface. It is considered that these anti-phase InN nuclei are formed by local fluctuations of stoichiometry due to inadequate surface migration during the growth of the InN buffer layer, indicating the important of controlling the surface stoichiometry during InN growth.

Microstructure of GaN Films Grown by RF-Plasma Assisted Molecular Beam Epitaxy

2000 ◽  
Vol 639 ◽  
Author(s):  
Philomela Komninou ◽  
Thomas Kehagias ◽  
Joseph Kioseoglou ◽  
Eirini Sarigiannidou ◽  
Theodoros Karakostas ◽  
...  
Keyword(s):  
Electron Microscopy ◽  
Low Temperature ◽  
Molecular Beam ◽  
Flux Ratio ◽  
Rf Plasma ◽  
Low Density ◽  
Transmission Electron ◽  
Cubic Gan ◽  
Gan Film ◽  
N Flux

ABSTRACTThe influence of the variation of the Ga/N flux ratio during deposition and of the different substrate nitridation temperatures on the microstructure of 2H-GaN films grown on (0001) sapphire, by RF plasma MBE, is investigated by conventional and high resolution Transmission Electron Microscopy (TEM-HREM). The different growth rates of the inverse polarity domains in Ga-rich and N-rich specimens result in film surfaces of different roughness, whereas the stacking fault (SF) content is significantly higher in samples grown under N-rich conditions. Low temperature nitridation of the substrate results in a low density of defects in GaN film. Cubic GaN “pockets”, near the substrate/GaN interface that are present in low temperature nitridated samples are not observed in high temperature nitridated samples.

Tin-Doping Induced Defects in GaAs Films Grown by Molecular Beam Epitaxy

1984 ◽  
Vol 41 ◽  
Author(s):  
S. H. Chen ◽  
P. Enquist ◽  
C. B. Carter
Keyword(s):  
Electron Microscopy ◽  
Transmission Electron Microscopy ◽  
Molecular Beam Epitaxy ◽  
Molecular Beam ◽  
Surface Region ◽  
Growth Conditions ◽  
Near Surface ◽  
Transmission Electron ◽  
Gaas Films ◽  
Induced Defects

AbstractHeavily Sn-doped GaAs films have been grown by molecular-beam epitaxy and found to contain single-crystal Sn particles situated in the near-surface region of the epilayer GaAs. The morphology and chemical composition of the particles have been examined by using cross-section transmission electron microscopy combined with energy-dispersive x-ray spectroscopy. Different growth conditions were used to study the Sn-particle formation and high-resolution transmission electron microscopy was used to investigate microstructures. The observations are discussed in terms of several models previously proposed for these phenomena.

Annealing Of Radiation Damage in Tungsten

1970 ◽  
Vol 28 ◽  
pp. 412-413
Author(s):  
Robert C. Rau ◽  
John Moteff
Keyword(s):  
Electron Microscopy ◽  
Transmission Electron Microscopy ◽  
Radiation Damage ◽  
Thermal Annealing ◽  
Neutron Fluence ◽  
Dislocation Loops ◽  
Defect Clusters ◽  
Polycrystalline Tungsten ◽  
Transmission Electron ◽  
Radiation Induced

Transmission electron microscopy has been used to study the thermal annealing of radiation induced defect clusters in polycrystalline tungsten. Specimens were taken from cylindrical tensile bars which had been irradiated to a fast (E > 1 MeV) neutron fluence of 4.2 × 1019 n/cm2 at 70°C, annealed for one hour at various temperatures in argon, and tensile tested at 240°C in helium. Foils from both the unstressed button heads and the reduced areas near the fracture were examined.Figure 1 shows typical microstructures in button head foils. In the unannealed condition, Fig. 1(a), a dispersion of fine dot clusters was present. Annealing at 435°C, Fig. 1(b), produced an apparent slight decrease in cluster concentration, but annealing at 740°C, Fig. 1(C), resulted in a noticeable densification of the clusters. Finally, annealing at 900°C and 1040°C, Figs. 1(d) and (e), caused a definite decrease in cluster concentration and led to the formation of resolvable dislocation loops.

Black-white contrast of dislocation loops

1978 ◽  
Vol 36 (1) ◽  
pp. 328-329
Author(s):  
J. J. Hren ◽  
W. D. Cooper ◽  
L. J. Sykes
Keyword(s):  
Electron Microscopy ◽  
Transmission Electron Microscopy ◽  
Dislocation Loops ◽  
Major Premise ◽  
Burgers Vector ◽  
Transmission Electron ◽  
Primary Means ◽  
Contrast Analysis ◽  
Dot Product ◽  
Imaging Conditions

Small dislocation loops observed by transmission electron microscopy exhibit a characteristic black-white strain contrast when observed under dynamical imaging conditions. In many cases, the topography and orientation of the image may be used to determine the nature of the loop crystallography. Two distinct but somewhat overlapping procedures have been developed for the contrast analysis and identification of small dislocation loops. One group of investigators has emphasized the use of the topography of the image as the principle tool for analysis. The major premise of this method is that the characteristic details of the image topography are dependent only on the magnitude of the dot product between the loop Burgers vector and the diffracting vector. This technique is commonly referred to as the (g•b) analysis. A second group of investigators has emphasized the use of the orientation of the direction of black-white contrast as the primary means of analysis.

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