Spatially Resolved Characterization of Microstructure, Defects and Tilts in GaN Layers Grown on Si(111) Substrates by Maskless Cantilever Epitaxy

2006 ◽  
Vol 934 ◽  
Author(s):  
Rozaliya Barabash ◽  
C. Roder ◽  
G. E. Ice ◽  
S. Einfeldt ◽  
J. D. Budai ◽  
...  
Keyword(s):  
Orientation Imaging Microscopy ◽  
Growth Conditions ◽  
Threading Dislocations ◽  
Misfit Dislocations ◽  
X Ray ◽  
Orientation Imaging ◽  
Spatially Resolved ◽  
Dislocation Arrays ◽  
Tilt Boundaries

ABSTRACTThe spatially resolved distribution of strain, misfit and threading dislocations, and crystallographic orientation in uncoalesced GaN layers grown on Si(111) substrates by maskless cantilever epitaxy was studied by white-beam Laue x-ray microdiffraction, scanning electron microscopy, and orientation imaging microscopy. Tilt boundaries formed at the column/wing interface with the misorientation strongly depending on the growth conditions. A depth-dependent deviatoric strain gradient is found in the GaN. Types and density of misfit dislocations as well as their arrangement within different dislocation arrays was quantified. The results are discussed with respect to the miscut of the Si(111) surface and misfit dislocations formed at the interface.

Microstructural study of GaAs epitaxial layers on Ge(100) substrates

1995 ◽  
Vol 10 (4) ◽  
pp. 843-852 ◽  
Author(s):  
N. Guelton ◽  
R.G. Saint-Jacques ◽  
G. Lalande ◽  
J-P. Dodelet
Keyword(s):  
Electron Microscopy ◽  
Surface Preparation ◽  
Growth Conditions ◽  
Vapor Transport ◽  
Threading Dislocations ◽  
Misfit Dislocations ◽  
Antiphase Boundaries ◽  
Microstructural Study ◽  
Mismatch Strain ◽  
Transmission Electron

GaAs layers grown by close-spaced vapor transport on (100) Ge substrates have been investigated as a function of the experimental growth conditions. The effects on the microstructure of the surface preparation, substrate misorientation, and annealing were studied using optical microscopy and transmission electron microscopy. Microtwins and threading dislocations are suppressed by oxide desorption before deposition. Single domain GaAs layers have been obtained using a 50 nm thick double domain buffer layer on an annealed Ge substrate misoriented 3°toward [011]. The mismatch strain is mainly accommodated by dissociated 60°dislocations. These misfit dislocations extend along the interface by the glide of the threading dislocations inherited from the substrate, but strong interaction with antiphase boundaries (APB's) prevents them from reaching the interface. These results are discussed and compared with previous reports of GaAs growth on Ge(100).

scholarly journals Spatially Resolved Characterization of Biogenic Manganese Oxide Production within a Bacterial Biofilm

2005 ◽  
Vol 71 (3) ◽  
pp. 1300-1310 ◽  
Author(s):  
Brandy Toner ◽  
Sirine Fakra ◽  
Mario Villalobos ◽  
Tony Warwick ◽  
Garrison Sposito
Keyword(s):  
Careful Consideration ◽  
Bacterial Biofilm ◽  
Bacterial Cells ◽  
X Ray ◽  
Spatially Resolved ◽  
Nexafs Spectroscopy ◽  
Promising Tool ◽  
Scanning Transmission ◽  
X Ray Absorption

ABSTRACT Pseudomonas putida strain MnB1, a biofilm-forming bacterial culture, was used as a model for the study of bacterial Mn oxidation in freshwater and soil environments. The oxidation of aqueous Mn+2 [Mn+2 (aq)] by P. putida was characterized by spatially and temporally resolving the oxidation state of Mn in the presence of a bacterial biofilm, using scanning transmission X-ray microscopy (STXM) combined with near-edge X-ray absorption fine structure (NEXAFS) spectroscopy at the Mn L2,3 absorption edges. Subsamples were collected from growth flasks containing 0.1 and 1 mM total Mn at 16, 24, 36, and 48 h after inoculation. Immediately after collection, the unprocessed hydrated subsamples were imaged at a 40-nm resolution. Manganese NEXAFS spectra were extracted from X-ray energy sequences of STXM images (stacks) and fit with linear combinations of well-characterized reference spectra to obtain quantitative relative abundances of Mn(II), Mn(III), and Mn(IV). Careful consideration was given to uncertainty in the normalization of the reference spectra, choice of reference compounds, and chemical changes due to radiation damage. The STXM results confirm that Mn+2 (aq) was removed from solution by P. putida and was concentrated as Mn(III) and Mn(IV) immediately adjacent to the bacterial cells. The Mn precipitates were completely enveloped by bacterial biofilm material. The distribution of Mn oxidation states was spatially heterogeneous within and between the clusters of bacterial cells. Scanning transmission X-ray microscopy is a promising tool for advancing the study of hydrated interfaces between minerals and bacteria, particularly in cases where the structure of bacterial biofilms needs to be maintained.

scholarly journals Characterization of dislocations in germanium layers grown on (011)- and (111)-oriented silicon by coplanar and noncoplanar X-ray diffraction

2015 ◽  
Vol 48 (3) ◽  
pp. 655-665 ◽  
Author(s):  
Andrei Benediktovitch ◽  
Alexei Zhylik ◽  
Tatjana Ulyanenkova ◽  
Maksym Myronov ◽  
Alex Ulyanenkov
Keyword(s):  
Dislocation Line ◽  
Complementary Metal Oxide Semiconductor ◽  
Metal Oxide Semiconductor ◽  
Oxide Semiconductor ◽  
Misfit Dislocations ◽  
X Ray Diffraction ◽  
X Ray ◽  
Lattice Constants ◽  
Silicon And Germanium

Strained germanium grown on silicon with nonstandard surface orientations like (011) or (111) is a promising material for various semiconductor applications, for example complementary metal-oxide semiconductor transistors. However, because of the large mismatch between the lattice constants of silicon and germanium, the growth of such systems is challenged by nucleation and propagation of threading and misfit dislocations that degrade the electrical properties. To analyze the dislocation microstructure of Ge films on Si(011) and Si(111), a set of reciprocal space maps and profiles measured in noncoplanar geometry was collected. To process the data, the approach proposed by Kaganer, Köhler, Schmidbauer, Opitz & Jenichen [Phys. Rev. B, (1997),55, 1793–1810] has been generalized to an arbitrary surface orientation, arbitrary dislocation line direction and noncoplanar measurement scheme.

Characterization of Structural Defects in Germanium Epitaxially Grown on Nano-Structured Silicon

2011 ◽  
Vol 178-179 ◽  
pp. 43-49 ◽  
Author(s):  
Peter Zaumseil ◽  
Yuji Yamamoto ◽  
Joachim Bauer ◽  
Markus Andreas Schubert ◽  
Jana Matejova ◽  
...  
Keyword(s):  
Oxide Thickness ◽  
Growth Conditions ◽  
Structural Defects ◽  
Misfit Dislocations ◽  
Strain Partitioning ◽  
X Ray Diffraction ◽  
Reduced Pressure ◽  
Periodic Arrays ◽  
Transmission Electron

Selective epitaxial growth of germanium (Ge) on nano-structured Si(001) wafers is studied to evaluate the applicability of the nano-heteroepitaxy (NHE) approach on Ge-Si system. Based on a gate spacer technology established in advanced silicon microelectronics periodic arrays of nano-scaled Si islands are prepared, where Ge is deposited on top by reduced pressure CVD. The spacing of these structures is 360 nm. The structural perfection of the deposited Ge is investigated by transmission electron microscopy and X-ray diffraction. It is found that SiO2used as masking material is responsible for the suppression of the desired strain partitioning effect according to NHE. Even for 10 nm oxide thickness, the lattice of Ge layers deposited on Si nano-islands relaxes completely by generation of misfit dislocations at the interface. The occurrence of additional structural defects like stacking faults and micro twins can be controlled by suited growth conditions.

Investigation of Semiconductor Heterostructures by White Beam Synchrotron X-Ray Topography in Grazing Bragg-Laue and Conventional Bragg Geometries

1991 ◽  
Vol 35 (A) ◽  
pp. 247-253
Author(s):  
G.-D. Yao ◽  
J. Wu ◽  
T. Fanning ◽  
M. Dudley
Keyword(s):  
Penetration Depth ◽  
Grazing Incidence ◽  
Semiconductor Heterostructures ◽  
Misfit Dislocations ◽  
Strained Layers ◽  
X Ray ◽  
Main Reflection ◽  
White Beam ◽  
Topographic Imaging

AbstractWhite beam synchrotron X-ray topography has been applied both to the characterization of two semiconductor heterostructures, GaAs/Si and InxGa1-xAs/GaAs strained layers, and a substrate to be used for growing semiconductor epilayers, Cd1-xZnxTe. In the case of the heterostructures, misfit dislocations were observed using depth sensitive X-ray topographic imaging in grazing incidence Bragg-Laue geometries. The X-ray penetration depth, which can be varied from several hundreds of angstroms to hundreds of micrometers by rotating about the main reflection vector, which in this specific case was (355), is governed by kinernatical theory. This is justified by comparing dislocation contrast and visibility with the extent of the calculated effective misorientalion field in comparison to the effective X-ray penetration depth. For the case of Cd1-xZnxTe, twin configurations are observed, and their analysis is presented.

scholarly journals Characterization of spatially resolved high resolution x-ray spectrometers for high energy density physics and light source experiments

2014 ◽  
Vol 85 (11) ◽  
pp. 11D612 ◽  
Author(s):  
K. W. Hill ◽  
M. Bitter ◽  
L. Delgado-Aparacio ◽  
P. Efthimion ◽  
N. A. Pablant ◽  
...  
Keyword(s):  
High Resolution ◽  
Energy Density ◽  
Light Source ◽  
High Energy ◽  
High Energy Density ◽  
X Ray ◽  
High Energy Density Physics ◽  
Spatially Resolved

MOCVD Growth and Characterization of High-Quality ZnSe on GaAs

1994 ◽  
Vol 340 ◽  
Author(s):  
J. C. Chen ◽  
Bing Yang ◽  
F. Semendy ◽  
W. W. Clark ◽  
P. R. Boyd ◽  
...  
Keyword(s):  
Electron Microscopy ◽  
Secondary Ion Mass Spectrometry ◽  
Defect Density ◽  
Growth Conditions ◽  
Misfit Dislocations ◽  
High Quality ◽  
Double Crystal ◽  
X Ray ◽  
Mocvd Growth ◽  
Order Of Magnitude

ABSTRACTHigh-quality ZnSe epilayers on GaAs substrates have been grown by MOCVD. Diethylzinc (DEZn) and diethylselenide (DESe) were used as source materials. Growth studies were done at 400°C under different growth conditions in an atmospheric pressure MOCVD reactor. The as-grown ZnSe epilayers were characterized by a wide variety of techniques, such as double crystal x-ray diffraction, low-temperature photoluminescence (PL), transmission electron microscopy (TEM), secondary ion mass spectrometry (SIMS), and scanning electron microscopy (SEM).The results show excellent structural and optical properties of ZnSe. The best material was grown on undoped GaAs at the VI/II ratio near unity. The full-width-at-half-maximum (FWHM) of ZnSe (∼0.2/μm thick) x-ray peak as low as 90 arc seconds was achieved. TEM results also show very low defect density. The density of stacking faults is less than 105/cm2 which is four orders of magnitude less than that of samples grown by conventional MBE [J. Petruzzello et al. J. Appl. Phys. 63, 2299 (1988)] and MOCVD [J.L. Batstone et al. Philos. Mag A, 66, 609, 1992]. The spacing between misfit dislocations is between 5 to 10,μm which is one order of magnitude larger than that of reported sample of comparable thickness.

scholarly journals Spatially Resolved Characterization of Electromigration-Induced Plastic Deformation in al (0.5WT% CU) Interconnect

2002 ◽  
Vol 738 ◽  
Author(s):  
R.I. Barabash ◽  
G.E. Ice ◽  
N. Tamura ◽  
J.R. Patel ◽  
B.C. Valek ◽  
...  
Keyword(s):  
Plastic Deformation ◽  
Dislocation Structure ◽  
Early Stage ◽  
X Ray ◽  
Spatially Resolved ◽  
Cu Interconnect ◽  
Interconnect Lines ◽  
Distributed Dislocations

ABSTRACTElectromigration during accelerated testing can induce early stage plastic deformation in Al interconnect lines as recently revealed by the white beam scanning X-ray microdiffraction. In the present paper, we provide a first quantitative analysis of the dislocation structure generated in individual micron-sized Al grains during anin-situelectromigration experiment. Laue reflections from individual interconnect grains show pronounced streaking after electric current flow. We demonstrate that the evolution of the dislocation structure during electromigration is highly inhomogeneous and results in the formation of unpaired randomly distributed dislocations as well as geometrically necessary dislocation boundaries. Approximately half of all unpaired dislocations are grouped within the walls. The misorientation created by each boundary and density of unpaired individual dislocations is determined.

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