A Tem Study Of The Microstructural Evolution Of Mbe-Grown Gan

1997 ◽  
Vol 482 ◽  
Author(s):  
David M. Tricker ◽  
Paul D. Brown ◽  
Graeme Martin ◽  
J. Lu ◽  
D. I. Westwood ◽  
...  
Keyword(s):  
Molecular Beam ◽  
Early Stage ◽  
Misfit Strain ◽  
High Energy ◽  
The Other ◽  
High Energy Electron ◽  
Zinc Blende ◽  
Gaas Substrates ◽  
Transmission Electron ◽  
Final Microstructure

AbstractThe evolution of the microstructure of GaN grown by molecular beam epitaxy on {001} and {111} oriented GaAs substrates has been followed using transmission electron microscopy and reflection high energy electron diffraction. A thin layer of GaN has been shown to form during the nitridation of the GaAs surface prior to growth. Growth of GaN then proceeds by an island mechanism. Faulting on the four {111} planes of the cubic zinc-blende phase which grows on the {001 } surface occurs at an early stage as a consequence of misfit strain. The distribution of the {111} microtwins is initially isotropic, but growth of one pair of {111} twins proceeds much faster than that of the other pair, leading to a final microstructure which has an anisotropic distribution of microtwins. Doping of GaN with Si hinders the growth of the zinc-blende phase, leading to a textured, columnar (0001) wurtzite microstructure. Evidence is presented to show that addition of Mg as a dopant may reduce the stacking fault energy of wurtzite GaN.

Epitaxial Si films Grown on Lattice Matched (LaxY1-x)O3/Si (111) Structures by Molecular Beam Epitaxy

2002 ◽  
Vol 747 ◽  
Author(s):  
V. Narayanan ◽  
S. Guha ◽  
N. A. Bojarczuk ◽  
M. Copel
Keyword(s):  
Molecular Beam ◽  
Early Stage ◽  
Three Dimensional ◽  
Stacking Faults ◽  
High Energy ◽  
High Energy Electron ◽  
Planar Defects ◽  
Transmission Electron ◽  
Si Films ◽  
Lattice Matched

ABSTRACTGrowth of epitaxial Si epitaxial overlayers on lattice matched (LaxY1-x)2O3/Si (LaYO/Si) structures has been investigated by high resolution transmission electron microscopy and reflection high energy electron diffraction. Results indicate that smooth two-dimensional near lattice-matched LaYO (111) films can be grown on Si (111) substrates. However, subsequent Si epitaxial growth on the LaYO/Si structures nucleates as three-dimensional islands, a consequence of the high energy of the Si overlayer/LaYO interface. We have investigated the effect of growth temperature on the microstructure of the Si overlayers. Higher temperatures resulted in the nucleation of large faceted islands and rough overlayers while lower temperatures result in smaller islands that coalesce at an early stage and produce smoother films. In addition, formation of planar defects in these films is attributed to stacking errors on the {111} facets of initial Si islands with lower temperatures resulting in a higher density of stacking faults and twins.

Temperature Dependent Quasi-Periodic Facetting of AlAs Grown by MBE on (100) GaAs Substrates

1993 ◽  
Vol 312 ◽  
Author(s):  
Richard Mirin ◽  
Mohan Krishnamurthy ◽  
James Ibbetson ◽  
Arthur Gossard ◽  
John English ◽  
...  
Keyword(s):  
Growth Conditions ◽  
High Energy ◽  
High Energy Electron ◽  
Temperature Dependent ◽  
Cross Sectional ◽  
Mbe Growth ◽  
Atomic Force ◽  
Gaas Substrates ◽  
Transmission Electron ◽  
Facet Formation

AbstractHigh temperature (≥ 650°C) MBE growth of AlAs and AlAs/GaAs superlattices on (100) GaAs is shown to lead to quasi-periodic facetting. We demonstrate that the facetting is only due to the AlAs layers, and growth of GaAs on top of the facets replanarizes the surface. We show that the roughness between the AlAs and GaAs layers increases with increasing number of periods in the superlattice. The roughness increases to form distinct facets, which rapidly grow at the expense of the (100) surface. Within a few periods of the initial facet formation, the (100) surface has disappeared and only the facet planes are visible in cross-sectional transmission electron micrographs. At this point, the reflection high-energy electron diffraction pattern is spotty, and the specular spot is a distinct chevron. We also show that the facetting becomes more pronounced as the substrate temperature is increased from 620°C to 710°C. Atomic force micrographs show that the valleys enclosed by the facets can be several microns long, but they may also be only several nanometers long, depending on the growth conditions.

Effects of substrates and catalysts compositions on the crystalline quality of InP Nanowires grown on SrTiO3 (001), Si(001) and InP (111)

2010 ◽  
Vol 1258 ◽  
Author(s):  
Khalid Naji ◽  
Herve Dumont ◽  
Guillaume Saint-Girons ◽  
Gilles Patriarche ◽  
michel Gendry
Keyword(s):  
Molecular Beam ◽  
Defect Formation ◽  
High Energy ◽  
Growth Direction ◽  
Crystalline Quality ◽  
Metal Catalyst ◽  
Cubic Phase ◽  
High Energy Electron ◽  
Transmission Electron

AbstractIndium phosphide (InP) nanowires (NWs) were grown by molecular beam epitaxy on various substrates including SrTiO3 (001), Si (001) and InP (111) at a growth temperature of 380°C. We used the Vapor Liquid Solid assisted method with Au as a metal catalyst. The composition of the catalyst particles and the crystalline structure of the nanowires were compared using reflection high energy electron diffraction, scanning electron microscopy and high resolution transmission electron microscope. It is found that InP nanowires grown onto InP and SrTiO3 substrates are structurally defects free with a wurtzite structure. On Si (001) substrates, the presence of stacking faults and cubic phase insertion along the growth direction is observed. The effect of the substrate on the composition of catalyst droplets and consequently on the crystalline quality of the nanowires is discussed for the conditions of nucleation and defect formation.

MBE-Grown Epitaxial Co/Cr Superlattices

1991 ◽  
Vol 231 ◽  
Author(s):  
W. Vavra ◽  
S. Elagoz ◽  
Roy Clarke ◽  
C. Uher
Keyword(s):  
Electron Microscopy ◽  
Transmission Electron Microscopy ◽  
Molecular Beam ◽  
High Energy ◽  
Squid Magnetometry ◽  
High Energy Electron ◽  
Deposition Rates ◽  
Saturation Field ◽  
Transmission Electron ◽  
Hall Effect Measurements

AbstractA series of epitaxial Co/Cr superlattices has been grown by molecular beam epitaxy. The Cr is in a metastable hcp phase as confirmed by transmission electron microscopy, selected area diffraction, and reflection high energy electron diffraction. The Cr layers are 10Å thick in all samples while the Co layers are varied from 12Å to 40Å. The diffusion between Co and Cr is studied by SQUID magnetometry and indicates step-like interfaces in the best samples. Interfacial sharpness has also been found to be unusually sensitive to Co deposition rates, and in contrast with other superlattice systems, we find that sharper interfaces enhance parallel anisotropy. Hall effect measurements of the saturation field are within 10% of SQUID values. Magnetoresistance at 4.2K is only 1/3% which we believe is a consequence of the high density of states at the Fermi level of hcp Cr.

The Heteronucleation of and Defect Generation in MBE-Grown InAs Layers

1988 ◽  
Vol 144 ◽  
Author(s):  
M. M. AI-Jassim ◽  
J. P. Goral ◽  
P. Sheldon ◽  
K. M. Jones
Keyword(s):  
Molecular Beam Epitaxy ◽  
Electron Diffraction ◽  
Molecular Beam ◽  
High Energy ◽  
Misfit Dislocations ◽  
High Energy Electron ◽  
Cross Sectional ◽  
Plan View ◽  
Gaas Substrates

ABSTRACTEpitaxial InAs layers were grown by molecular beam epitaxy (MBE) on GaAs substrates. The initial stages of nucleation were studied by in situ reflection high energy electron diffraction (RHEED). Cross-sectional TEM examination was used to investigate the morphology of the growing layer, while plan-view examination revealed the generation of misfit dislocations. The growth mode was found to depend mainly on the conditions used to nucleate the epitaxial layer. In most cases, Stranski-Krastanov type of growth was observed.

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