Lattice constant variation in GaN:Si layers grown by HVPE

2002 ◽  
Vol 743 ◽  
Author(s):  
A. Usikov ◽  
O. V. Kovalenkov ◽  
M. M. Mastro ◽  
D. V. Tsvetkov ◽  
A. I. Pechnikov ◽  
...  
Keyword(s):  
Defect Formation ◽  
Strain Relaxation ◽  
Growth Conditions ◽  
Optical And Electrical Properties ◽  
X Ray Diffraction ◽  
Proper Selection ◽  
X Ray ◽  
Lattice Constants ◽  
Si Doping ◽  
Selection Of

ABSTRACTThe structural, optical, and electrical properties of HVPE-grown GaN-on-sapphire templates were studied. The c and a lattice constants of the GaN layers were measured by x-ray diffraction. It was observed that the c and a lattice constants vary non-monotonically with Si-doping. The proper selection of Si-doping level and growth conditions resulted in controllable strain relaxation, and thus, influenced defect formation in GaN-on-sapphire templates. It was also observed that HVPE homoepitaxial GaN layers grown on the templates have better crystal quality and surface morphology than the initial templates.

Selective Area Heteroepitaxy of Nano-AlGaN UV Excitation Sources for Biofluorescence Application

2006 ◽  
Vol 916 ◽  
Author(s):  
Vibhu Jindal ◽  
James Grandusky ◽  
Fatemeh Shahedipour-Sandvik ◽  
Steven LeBoeuf ◽  
Joleyn Balch ◽  
...  
Keyword(s):  
Growth Rate ◽  
Growth Parameters ◽  
Growth Conditions ◽  
X Ray Diffraction ◽  
High Quality ◽  
X Ray ◽  
Selective Area ◽  
Mask Material ◽  
Uv Excitation ◽  
Selection Of

AbstractWe report on the selective area heteroepitaxy and facet evolution of AlGaN nanostructures on GaN/sapphire substrate using various mask materials. We also report on the challenges associated with selection of an appropriate mask material for selective area heteroepitaxy of AlGaN with varying Al composition. The shape and the growth rate of the nanostructures are observed to be greatly affected by the mask material. The evolution of the AlGaN nanostructures and Al incorporation were studied exhaustively as a function of growth parameters; including temperature, pressure, NH3 flow, total alkyl flow and TMAl/(TMAl+TMGa) ratio. The growth rate of nanostructures was reduced drastically when higher Al percentage AlGaN nanostructures were grown. The growth rates were increased for higher Al percentage AlGaN using a surfactant which resulted in a high quality pyramidal structure. As indicated by high resolution x-ray diffraction (XRD) and cathodoluminescence (CL) spectroscopy, composition of Al in the AlGaN nanostructure is significantly different from that of a thin film grown under the same growth conditions.

Selective area heteroepitaxy of nano-AlGaN ultraviolet excitation sources for biofluorescence application

2007 ◽  
Vol 22 (4) ◽  
pp. 838-844 ◽  
Author(s):  
Vibhu Jindal ◽  
James R. Grandusky ◽  
Neeraj Tripathi ◽  
Fatemeh Shahedipour-Sandvik ◽  
Steven LeBoeuf ◽  
...  
Keyword(s):  
Growth Rate ◽  
Growth Parameters ◽  
Growth Conditions ◽  
X Ray Diffraction ◽  
X Ray ◽  
Ultraviolet Excitation ◽  
Selective Area ◽  
Cathodoluminescence Spectroscopy ◽  
Mask Material ◽  
Selection Of

We report on the selective area heteroepitaxy and facet evolution of AlGaN nanostructures on GaN/sapphire substrate using various mask materials. We also report on the challenges associated with selection of an appropriate mask material for selective area heteroepitaxy of AlGaN with varying Al composition. The shape and the growth rate of the nanostructures are observed to be greatly affected by the mask material. The evolution of the AlGaN nanostructures and Al incorporation were studied exhaustively as a function of growth parameters including temperature, pressure, NH3 flow, total alkyl flow, and TMAl/(TMAl+TMGa) ratio. The growth rate of nanostructures was reduced drastically when higher Al percentage AlGaN nanostructures were grown. The growth rates were increased for higher Al percentage AlGaN using a surfactant, which resulted in a high-quality pyramidal structure. As indicated by high-resolution x-ray diffraction and cathodoluminescence spectroscopy, the composition of Al in the AlGaN nanostructure is significantly different from that of a thin film grown under the same growth conditions.

Stress and its Effect on Intermixing in Si1-xGex/Si Superlattices

1994 ◽  
Vol 356 ◽  
Author(s):  
S. M. Prokes
Keyword(s):  
Raman Spectroscopy ◽  
Tensile Stress ◽  
Defect Formation ◽  
Growth Conditions ◽  
External Stress ◽  
X Ray Diffraction ◽  
Strained Si ◽  
X Ray ◽  
Long Period ◽  
Kinetics Of

AbstractInterdiffusion behavior in long-period Si1-xGex/Si as a function of growth conditions and external stress is examined using x-ray diffraction and Raman Spectroscopy. Both symmetrically and asymmetrically-strained superlattices have been examined, and an activation energy for interdiffusion of 3.9 eV and 4.6 eV have been obtained, respectively. In addition, an enhanced interdiffusion has also been measured in an externally stressed asymmetric superlattice. In both cases, enhanced interdiffusion has been measured whenever the Si barrier layers experience tensile stress during annealing. The Raman spectroscopy supports this result, showing an enhanced Ge diffusion into the Si barriers when these barriers are put under tensile stress. This result will be discussed in terms of the kinetics of defect formation and motion in the strained Si barriers.

Lead titanate nano- and microtubes

2006 ◽  
Vol 21 (3) ◽  
pp. 685-690 ◽  
Author(s):  
Lili Zhao ◽  
Martin Steinhart ◽  
Jian Yu ◽  
Ulrich Gösele
Keyword(s):  
Lead Titanate ◽  
Porous Alumina ◽  
Macroporous Silicon ◽  
X Ray Diffraction ◽  
Proper Selection ◽  
X Ray ◽  
Inorganic Oxides ◽  
Precise Adjustment ◽  
Ordered Porous ◽  
Selection Of

Lead titanate (PbTiO3) nano- and microtubes were fabricated by wetting ordered porous alumina and macroporous silicon with precursor oligomers coupled with templated thermolysis. The diameters of the PbTiO3 tubes range from a few tens of nanometers up to one micron. The proper selection of the template allowed for a precise adjustment of their size over two orders of magnitude. Electron microscopy and x-ray diffraction revealed that the tube walls were polycrystalline. The generic approach presented here can be adapted for the fabrication of tubes and rods from a multitude of functional inorganic oxides.

Measurement of strain in InGaN/GaN nanowires and nanopyramids

2015 ◽  
Vol 48 (2) ◽  
pp. 344-349 ◽  
Author(s):  
Tomaš Stankevič ◽  
Simas Mickevičius ◽  
Mikkel Schou Nielsen ◽  
Olga Kryliouk ◽  
Rafal Ciechonski ◽  
...  
Keyword(s):  
Lattice Mismatch ◽  
Strain Relaxation ◽  
Shell Growth ◽  
X Ray Diffraction ◽  
X Ray ◽  
Lattice Constants ◽  
Shell Nanostructures ◽  
Vegard’S Law ◽  
Planar Films ◽  
The Individual

The growth and optoelectronic properties of core–shell nanostructures are influenced by the strain induced by the lattice mismatch between core and shell. In contrast with planar films, nanostructures contain multiple facets that act as independent substrates for shell growth, which enables different relaxation mechanisms. In this study, X-ray diffraction data are presented that show that InαGa1−αN shells grown on GaN cores are strained along each of the facets independently. Reciprocal space maps reveal multiple Bragg peaks, corresponding to different parts of the shell being strained along the individual facet planes. The strained lattice constants were found from the positions of the Bragg peaks. Vegard's law and Hooke's law for an anisotropic medium were applied in order to find the composition and strain in the InGaN shells. A range of nanowire samples with different InGaN shell thicknesses were measured and it is concluded that, with an In concentration of around 30%, major strain relaxation takes place when the thickness reaches 23 nm. InGaN shells of 6 and 9 nm thickness remain nearly fully strained biaxially along each of the \{10{\overline 1}0\} facets of the nanowires and the \{10{\overline 1}1\} facets of the nanopyramids.

scholarly journals CADEM: calculate X-ray diffraction of epitaxial multilayers

2017 ◽  
Vol 50 (1) ◽  
pp. 288-292 ◽  
Author(s):  
Paulina Komar ◽  
Gerhard Jakob
Keyword(s):  
Strain Relaxation ◽  
Diffraction Theory ◽  
Layer By Layer ◽  
Material System ◽  
X Ray Diffraction ◽  
X Ray ◽  
Lattice Constants ◽  
Out Of Plane ◽  
Xrd Patterns ◽  
Epitaxial Multilayers

Epitaxial multilayers and superlattice (SL) structures are gaining increasing importance as they offer the opportunity to create artificial crystals with new functionalities. These crystals deviate from the parent bulk compounds not only in terms of the lattice constants but also in the symmetry classification, which renders calculation of their X-ray diffraction (XRD) patterns tedious. Nevertheless, XRD is essential to get information on the multilayer/SL structure such as, for example, out-of-plane lattice constants, strain relaxation and period length of the crystalline SL. This article presents a powerful yet simple program, based on the general one-dimensional kinematic X-ray diffraction theory, which calculates the XRD patterns of tailor-made multilayers and thus enables quantitative comparison of measured and calculated XRD data. As the multilayers are constructed layer by layer, the final material stack can be entirely arbitrary. Moreover, CADEM is very flexible and can be straightforwardly adapted to any material system. The source code of CADEM is available as supporting material for this article.

Study on TlBr Single Crystal Growth Using Improved Electro Dynamic Gradient Method

2011 ◽  
Vol 415-417 ◽  
pp. 1979-1982
Author(s):  
Zhi Ping Zheng ◽  
Jing Wang ◽  
Lin Quan ◽  
Shu Ping Gong ◽  
Dong Xiang Zhou
Keyword(s):  
Growth Rate ◽  
Crystal Growth ◽  
Electrical Properties ◽  
Temperature Gradient ◽  
Growth Conditions ◽  
Single Crystal Growth ◽  
Optical And Electrical Properties ◽  
X Ray Diffraction ◽  
X Ray

Electro Dynamic Gradient (EDG) method was utilized for TlBr crystal growth in this paper. The influence of crystal growth conditions such as temperature gradient and growth rate on optical and electrical properties of grown TlBr crystals was investigated. The quality of TlBr crystals was characterized by infrared (IR) transmittance spectrum, X-ray diffraction, and I-V measurements.

Preparation and Characterisation of TiO2 Thick Films Fabricated by Electrophoretic Deposition

2007 ◽  
Vol 561-565 ◽  
pp. 2163-2166 ◽  
Author(s):  
H.Z. Abdullah ◽  
Charles C. Sorrell
Keyword(s):  
Electron Microscopy ◽  
Scanning Electron Microscopy ◽  
Grain Growth ◽  
Electrophoretic Deposition ◽  
Defect Formation ◽  
Titanium Foil ◽  
X Ray Diffraction ◽  
Voltage Range ◽  
X Ray ◽  
Scanning Electron

Rutile nano-powders were suspended in a solution of acetylacetone and iodine. The suspensions were electrophoretically deposited on titanium foil at a voltage range of 5-30 V over times of 5-120 s. The dried tapes then were sintered at 800°C for 2 h in flowing argon. Both the green and fired tapes were examined by field emission scanning electron microscopy, optical microscopy, X-ray diffraction, and Raman microspectroscopy. The thickness of the films depended on the voltage and the time of deposition. The sintered microstructures depended significantly on the thickness of the film, which was a function the proximity to the Ti/TiO2 interface. The interface is critical to the microstructure because it acts as the source of defect formation, which enhances sintering, grain growth, and grain facetting.

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