scholarly journals Epitaxial Growth of Ordered In-Plane Si and Ge Nanowires on Si (001)

Nanomaterials ◽  
2021 ◽  
Vol 11 (3) ◽  
pp. 788
Author(s):  
Jian-Huan Wang ◽  
Ting Wang ◽  
Jian-Jun Zhang
Keyword(s):  
Electron Microscopy ◽  
Epitaxial Growth ◽  
Molecular Beam ◽  
Core Shell ◽  
High Quality ◽  
Quantum Devices ◽  
Wafer Scale ◽  
Transmission Electron ◽  
Controllable Growth

Controllable growth of wafer-scale in-plane nanowires (NWs) is a prerequisite for achieving addressable and scalable NW-based quantum devices. Here, by introducing molecular beam epitaxy on patterned Si structures, we demonstrate the wafer-scale epitaxial growth of site-controlled in-plane Si, SiGe, and Ge/Si core/shell NW arrays on Si (001) substrate. The epitaxially grown Si, SiGe, and Ge/Si core/shell NW are highly homogeneous with well-defined facets. Suspended Si NWs with four {111} facets and a side width of about 25 nm are observed. Characterizations including high resolution transmission electron microscopy (HRTEM) confirm the high quality of these epitaxial NWs.

CHARACTERIZATION AND ELECTRICAL PROPERTIES OF ALIGNED CARBON NANOTUBES WITH HIGH ASPECT RATIO

2011 ◽  
Vol 10 (01n02) ◽  
pp. 23-28
Author(s):  
RAVI BHATIA ◽  
V. PRASAD ◽  
M. REGHU
Keyword(s):  
Electron Microscopy ◽  
Carbon Nanotubes ◽  
Aspect Ratio ◽  
Multiwall Carbon Nanotubes ◽  
High Quality ◽  
Transmission Electron Microscopy Analysis ◽  
Transmission Electron ◽  
Electron Microscopy Analysis ◽  
High Degree

High-quality multiwall carbon nanotubes (MWNTs) were produced by a simple one-step technique. The production of MWNTs was based on thermal decomposition of the mixture of a liquid phase organic compound and ferrocene. High degree of alignment was noticed by scanning electron microscopy. The aspect ratio of as-synthesized MWNTs was quite high (more than 4500). Transmission electron microscopy analysis showed the presence of the catalytic iron nanorods at various lengths of MWNTs. Raman spectroscopy was used to know the quality of MWNTs. The ratio of intensity of the G-peak to the D-peak was very high which revealed high quality of MWNTs. Magnetotransport studies were carried out at low temperature and a negative MR was noticed.

Characterization and Growth Mechanism of B12As2 Epitaxial Layers Grown on (1-100) 15R-SiC

2008 ◽  
Vol 1069 ◽  
Author(s):  
Hui Chen ◽  
Guan Wang ◽  
Michael Dudley ◽  
Zhou Xu ◽  
James. H. Edgar ◽  
...  
Keyword(s):  
Electron Microscopy ◽  
Transmission Electron Microscopy ◽  
High Resolution ◽  
Growth Mechanism ◽  
Heteroepitaxial Growth ◽  
High Quality ◽  
X Ray ◽  
Transmission Electron ◽  
Substrate Choice

ABSTRACTA systematic study is presented of the heteroepitaxial growth of B12As2 on m-plane 15R-SiC. In contrast to previous studies of B12As2 on other substrates, including (100) Si, (110) Si, (111) Si and (0001) 6H-SiC, single crystalline and untwinned B12As2 was achieved on m-plane 15R-SiC. Observations of IBA on m-plane (1100)15R-SiC by synchrotron white beam x-ray topography (SWBXT) and high resolution transmission electron microscopy (HRTEM) confirm the good quality of the films on the 15R-SiC substrates. The growth mechanism of IBA on m-plane 15R-SiC is discussed. This work demonstrates that m-plane 15R-SiC is potentially a good substrate choice to grow high quality B12As2 epilayers.

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.

Microstructure and growth of joins in melt-textured YBa2Cu3O7−δ

2001 ◽  
Vol 16 (8) ◽  
pp. 2298-2305 ◽  
Author(s):  
A. D. Bradley ◽  
W. Lo ◽  
M. Mironova ◽  
N. H. Babu ◽  
D. A. Cardwell ◽  
...  
Keyword(s):  
Electron Microscopy ◽  
Transmission Electron Microscopy ◽  
Liquid Phase ◽  
Grain Boundary ◽  
Electron Probe ◽  
High Quality ◽  
Strongly Coupled ◽  
External Agent ◽  
Transmission Electron

Joining of melt-textured YBa2Cu3O7-δ (Y123) grains has been achieved without use of an external agent. The technique uses barium-cuprate liquid phase released from platelet boundaries to mediate the growth of Y123 at the interface between two grains. The epitaxial nature and high quality of the growth was determined by optical and transmission electron microscopy. The composition of Ba–Cu–O phases found in some parts of the joins was determined by electron probe microanalysis. A clean low-angle join was found to consist of a grain boundary with dislocation networks and facets. Transport critical current measurements on this type of join revealed strongly coupled behavior. The technique shows promise for the joining of melt-textured material for power engineering applications.

Molecular Beam Epitaxial Growth of Cdl-xznxTe Matched to HgCdTe Alloys

1986 ◽  
Vol 90 ◽  
Author(s):  
N. Magnea ◽  
F. Dal'bo ◽  
J. L. Pautrat ◽  
A. Million ◽  
L. Di Cioccio ◽  
...  
Keyword(s):  
Electron Microscopy ◽  
Transmission Electron Microscopy ◽  
Molecular Beam ◽  
Bulk Material ◽  
Strained Layers ◽  
Molecular Beam Epitaxial ◽  
Transmission Electron ◽  
Molecular Beam Epitaxial Growth ◽  
Thick Layers

ABSTRACTCD1−xZnxTe alloys of various composition have been grown by the Molecular Beam Epitaxy Technique and characterized by Transmission Electron Microscopy. C(V) measurements and photoluminescence spectroscopy techniques. The quality of the thick layers is comparable to that of bulk material. Thin strained layers have also been grown whose interfaces are structurally good. The recombination within a CdTe well confined between Cd1−xZnxTe barriers is dominated by intrinsic processes.

IMPROVED CHEMICAL SYNTHESIS OF GRAPHENE USING A SAFER SOLVOTHERMAL ROUTE

2011 ◽  
Vol 10 (01n02) ◽  
pp. 39-42 ◽  
Author(s):  
DILIP KUMAR SINGH ◽  
P. K. IYER ◽  
P. K. GIRI
Keyword(s):  
Electron Microscopy ◽  
Graphene Sheets ◽  
Pyrolysis Process ◽  
High Quality ◽  
Force Microscopy ◽  
Atomic Force ◽  
Transmission Electron ◽  
Afm Analysis ◽  
Bulk Production

Graphene has been synthesized using thermal decomposition of ethyl alcohol in a medium pressure autoclave. The synthesis was carried out in the presence of strong alkaline solution at a temperature of ~230°C and pressure of 60 bar. The as-synthesized graphene has been characterized using atomic force microscopy (AFM) and high-resolution transmission electron microscopy (HRTEM). AFM analysis on various graphene sheets shows the presence of monolayer (n = 1) to trilayer (n = 3) graphene sheets with thickness of ~1.168 nm. HRTEM studies confirm the high quality of graphene obtained after purification of as-synthesized product. Use of chemically nonexplosive material for synthesis and reduced reaction time along with the absence of post-pyrolysis process make it a commercially viable process for bulk production of graphene.

scholarly journals Bi Incorporation and Segregation in the MBE-Grown GaAs-(Ga,Al)As-Ga(As,Bi) Core-Shell Nanowires

2021 ◽  
Author(s):  
Janusz Sadowski ◽  
Anna Kaleta ◽  
Serhii Kryvyi ◽  
Dorota Janaszko ◽  
Bogusława Kurowska ◽  
...  
Keyword(s):  
Electron Microscopy ◽  
Transmission Electron Microscopy ◽  
Molecular Beam ◽  
Flux Ratio ◽  
Growth Conditions ◽  
Nanowire Growth ◽  
Core Shell ◽  
Zinc Blende ◽  
Transmission Electron ◽  
Shell Nanowires

Abstract Incorporation of Bi into GaAs-(Ga,Al)As-Ga(As,Bi) core-shell nanowires grown by molecular beam epitaxy is studied with transmission electron microscopy. Nanowires are grown on GaAs(100) substrates with Au-droplet assisted mode. Bi-doped shells are grown at low temperature (300 °C) with a close to stoichiometric Ga/As flux ratio. At low Bi fluxes, the Ga(As,Bi) shells are smooth, with Bi completely incorporated into the shells. Higher Bi fluxes (Bi/As flux ratio ~ 4%) led to partial segregation of Bi as droplets on the nanowires sidewalls, preferentially located at the nanowire segments with wurtzite structure. We demonstrate that such Bi droplets on the sidewalls act as catalysts for the growth of branches perpendicular to the GaAs trunks. Due to the tunability between zinc-blende and wurtzite polytypes by changing the nanowire growth conditions, this effect enables fabrication of branched nanowire architectures with branches generated from selected (wurtzite) nanowire segments.

Tem Study of Temperature Influence on The Crystalline Quality of InGaAs/Si Epilayers

1992 ◽  
Vol 263 ◽  
Author(s):  
A. Vila ◽  
A. Cornet ◽  
J.R. Morante ◽  
D.I. Westwood
Keyword(s):  
Electron Microscopy ◽  
Transmission Electron Microscopy ◽  
Molecular Beam ◽  
Temperature Influence ◽  
X Ray Diffraction ◽  
Double Crystal ◽  
X Ray ◽  
Transmission Electron ◽  
Different Temperatures

ABSTRACTA Transmission Electron Microscopy (TEM) study of In0.53Ga0.47As Molecular Beam Epitaxy films grown at different temperatures onto misoriented Si (100) substrates is presented. The evolution of the density of the different kind of defects is discussed as a function of the growth temperature in the range between 200 and 500° C. The results are compared with the characterization techniques of Double Crystal X-Ray Diffraction and Hall effect.

Defect Structures in Heteroepitaxial InAs/GaAs and GaAs/InAs Grown by Atomic Layer Molecular Beam Epitaxy

1992 ◽  
Vol 262 ◽  
Author(s):  
S. I. Molina ◽  
G. Aragon ◽  
R. Garcia
Keyword(s):  
Electron Microscopy ◽  
Transmission Electron Microscopy ◽  
Molecular Beam Epitaxy ◽  
Molecular Beam ◽  
Atomic Layer ◽  
Defect Structures ◽  
Planar Defects ◽  
Transmission Electron

ABSTRACTA Transmission Electron Microscopy (TEM) study on ALMBE grown InAs/GaAs (001) is presented. The density and the types of defects contained in InAs and GaAs layers are clearly different. A relation between the planar defects in these layers and the compressive and extensive nature of the growth for each layer is found. Atomic Layer Molecular Beam Epitaxy (ALMBE) grown InAs layers possess a better quality of defects than other InAs layers grown on GaAs (001) by conventional MBE. Several ways of nucleation are presented as possible for explaining the existence of the different defects found in the studied heterostructure.

scholarly journals Mechanism for Improved Quality B12As2 Epitaxial Films on (0001) 4H-SiC Substrates by Tilting toward [1-100] Direction

2010 ◽  
Vol 1246 ◽  
Author(s):  
Yu Zhang ◽  
Hui Chen ◽  
Michael Dudley ◽  
Yi Zhang ◽  
James Edgar ◽  
...  
Keyword(s):  
Electron Microscopy ◽  
Substrate Surface ◽  
Epitaxial Films ◽  
High Quality ◽  
X Ray ◽  
Transmission Electron ◽  
Device Applications ◽  
Substrate Choice ◽  
Single Orientation

AbstractIn this work, 4H-SiC substrates intentionally misoriented from the (0001) plane toward [1-100] direction are shown to eliminate rotational twinning in icosahedral boron arsenide (B12As2, abbreviated here as IBA) epitaxial films. Previous studies of IBA on other substrates, including (100), (110), (111) Si and (0001) 6H-SiC, produced polycrystalline and twinned epilayers. Comparisons of IBA on on-axis and off-axis c-plane 4H-SiC by synchrotron white beam x-ray topography (SWBXT), and high resolution transmission electron microscopy (HRTEM) confirm the single crystalline and much higher quality of the films on the latter substrates. Furthermore, no intermediate layer between the epilayer and substrate was observed for IBA on off-axis 4H-SiC. Steps formed on the off-axis 4H-SiC substrate surface before deposition cause the film to adopt a single orientation, a process that is not seen with substrates with either no misorientation, or those tilted toward the [11-20] direction. This work demonstrates that c-plane 4H-SiC with 7° offcut toward (1-100) is potentially a good substrate choice for the growth of high-quality, untwinned B12As2 epilayers for future device applications.

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