On the microstructure, chemistry, and dielectric function of BaTiO3 MOCVD thin films

1994 ◽  
Vol 9 (2) ◽  
pp. 426-430 ◽  
Author(s):  
V.P. Dravid ◽  
H. Zhang ◽  
L.A. Wills ◽  
B.W. Wessels
Keyword(s):  
Thin Films ◽  
Electron Diffraction ◽  
Dielectric Function ◽  
Lattice Strain ◽  
Chemical Vapor ◽  
Convergent Beam Electron Diffraction ◽  
Organic Chemical ◽  
Beam Electron ◽  
Spatially Resolved ◽  
Convergent Beam

Thin films of BaTiO3 deposited on (100)LaAlO3 substrate by metal-organic chemical vapor deposition (MOCVD) are investigated using several electron-optical techniques. Combined high resolution transmission electron microscopy (HRTEM), electron energy loss spectrometry (EELS), and convergent beam electron diffraction (CBED) indicate a substantial influence of lattice strain on the structural and optical characteristics of BaTiO3 films. Spatially resolved EELS and CBED studies indicate that the substrate influence persists up to about 40 nm away from the interface. The changes in the dielectric function of the films, as inferred from spatially resolved EELS, appear to correlate well with internal lattice strain in the films as deduced from convergent beam electron diffraction (CBED).

Burgers Vector Analysis of Vertical Dislocations in Ge Crystals by Large-Angle Convergent Beam Electron Diffraction

2015 ◽  
Vol 21 (3) ◽  
pp. 637-645 ◽  
Author(s):  
Heiko Groiss ◽  
Martin Glaser ◽  
Anna Marzegalli ◽  
Fabio Isa ◽  
Giovanni Isella ◽  
...  
Keyword(s):  
Electron Diffraction ◽  
Large Angle ◽  
Three Dimensional ◽  
Chemical Vapor ◽  
Dark Field ◽  
Convergent Beam Electron Diffraction ◽  
Vector Analysis ◽  
Burgers Vector ◽  
Beam Electron ◽  
Convergent Beam

AbstractBy transmission electron microscopy with extended Burgers vector analyses, we demonstrate the edge and screw character of vertical dislocations (VDs) in novel SiGe heterostructures. The investigated pillar-shaped Ge epilayers on prepatterned Si(001) substrates are an attempt to avoid the high defect densities of lattice mismatched heteroepitaxy. The Ge pillars are almost completely strain-relaxed and essentially defect-free, except for the rather unexpected VDs. We investigated both pillar-shaped and unstructured Ge epilayers grown either by molecular beam epitaxy or by chemical vapor deposition to derive a general picture of the underlying dislocation mechanisms. For the Burgers vector analysis we used a combination of dark field imaging and large-angle convergent beam electron diffraction (LACBED). With LACBED simulations we identify ideally suited zeroth and second order Laue zone Bragg lines for an unambiguous determination of the three-dimensional Burgers vectors. By analyzing dislocation reactions we confirm the origin of the observed types of VDs, which can be efficiently distinguished by LACBED. The screw type VDs are formed by a reaction of perfect 60° dislocations, whereas the edge types are sessile dislocations that can be formed by cross-slips and climbing processes. The understanding of these origins allows us to suggest strategies to avoid VDs.

Nanopipes and Inversion Domains in High-Quality GaN Epitaxial Layers

1996 ◽  
Vol 449 ◽  
Author(s):  
F. A. Ponce ◽  
W. T. Young ◽  
D. Cherns ◽  
J. W. Steeds ◽  
S. Nakamura
Keyword(s):  
Electron Microscopy ◽  
Thin Films ◽  
Electron Diffraction ◽  
Convergent Beam Electron Diffraction ◽  
The Other ◽  
High Quality ◽  
Beam Electron ◽  
Convergent Beam ◽  
And Inversion ◽  
Conventional Electron Microscopy

ABSTRACTIn this paper we report that, in addition to dislocations, two other types of defects are observed in high quality GaN thin films. These defects have a filamentary nature, are oriented along the <0001> direction. and may not be easily distinguished from the pure dislocations. Using a combination of conventional electron microscopy with convergent beam electron diffraction techniques we show that one of these types of dislocations consist of nanopipes, which are coreless dislocations with Burgers vectors <0001>. The other type of observed defects consist of inversion domains with [0001 ] orientation within the [0001] matrix. The origin of the inversion domains and nanopipes is discussed.

Lattice strain and static disorder determination inSi/Si1−xGex/Siheterostructures by convergent beam electron diffraction

1999 ◽  
Vol 60 (19) ◽  
pp. 13750-13761 ◽  
Author(s):  
Stefano Frabboni ◽  
Francesca Gambetta ◽  
Aldo Armigliato ◽  
Roberto Balboni ◽  
Simone Balboni ◽  
...  
Keyword(s):  
Electron Diffraction ◽  
Lattice Strain ◽  
Convergent Beam Electron Diffraction ◽  
Static Disorder ◽  
Beam Electron ◽  
Convergent Beam
Sign in / Sign up

Export Citation Format

Share Document