Organometallic epitaxy of HgCdTe on CdTeSe substrates with high compositional uniformity

1988 ◽  
Vol 52 (5) ◽  
pp. 392-394 ◽  
Author(s):  
Sorab K. Ghandhi ◽  
Ishwara B. Bhat ◽  
Hamid Fardi
Keyword(s):  
Compositional Uniformity ◽  
Organometallic Epitaxy

scholarly journals Boron Influence on Defect Structure and Properties of Lithium Niobate Crystals

Crystals ◽  
2021 ◽  
Vol 11 (5) ◽  
pp. 458
Author(s):  
Nikolay V. Sidorov ◽  
Natalia A. Teplyakova ◽  
Olga V. Makarova ◽  
Mikhail N. Palatnikov ◽  
Roman A. Titov ◽  
...  
Keyword(s):  
Lithium Niobate ◽  
Defect Structure ◽  
Photorefractive Effect ◽  
Ferroelectric Properties ◽  
High Concentration ◽  
Oh Groups ◽  
Boron Doped ◽  
Compositional Uniformity ◽  
Boron Dopant ◽  
Lithium Niobate Crystals

Defect structure of nominally pure lithium niobate crystals grown from a boron doped charge have been studied by Raman and optical spectroscopy, laser conoscopy, and photoinduced light scattering. An influence of boron dopant on optical uniformity, photoelectrical fields values, and band gap have been also studied by these methods in LiNbO3 crystals. Despite a high concentration of boron in the charge (up to 2 mol%), content in the crystal does not exceed 10−4 wt%. We have calculated that boron incorporates only into tetrahedral voids of crystal structure as a part of groups [BO3]3−, which changes O–O bonds lengths in O6 octahedra. At this oxygen–metal clusters MeO6 (Me: Li, Nb) change their polarizability. The clusters determine optically nonlinear and ferroelectric properties of a crystal. Chemical interactions in the system Li2O–Nb2O5–B2O3 have been considered. Boron, being an active element, structures lithium niobate melt, which significantly influences defect structure and physical properties of a crystal grown from such a melt. At the same time, amount of defects NbLi and concentration of OH groups in LiNbO3:B is close to that in stoichiometric crystals; photorefractive effect, optical, and compositional uniformity on the contrary is higher.

scholarly journals Eocene-Oligocene sedimentation in the external areas of the Moldavide Basin (Marginal Folds Nappe, Eastern Carpathians, Romania): sedimentological, paleontological and petrographic approaches

2009 ◽  
Vol 60 (5) ◽  
pp. 397-417 ◽  
Author(s):  
Crina Miclăuş ◽  
Francesco Loiacono ◽  
Diego Puglisi ◽  
Dorin Baciu
Keyword(s):  
Source Area ◽  
Late Eocene ◽  
Low Rank ◽  
Coarse Grained ◽  
Facies Association ◽  
Compositional Uniformity ◽  
Eastern Carpathians ◽  
Extensional Tectonic ◽  
Facies Associations ◽  
Depositional Systems

Eocene-Oligocene sedimentation in the external areas of the Moldavide Basin (Marginal Folds Nappe, Eastern Carpathians, Romania): sedimentological, paleontological and petrographic approachesThe Marginal Folds Nappe is one of the most external tectonic units of the Moldavide Nappe System (Eastern Carpathians), formed by Cretaceous to Tertiary flysch and molasse deposits, piled up during the Miocene closure of the East Carpathian Flysch basin, cropping out in several tectonic half-windows, the Bistriţa half-window being one of them. The deposits of this tectonic unit were accumulated in anoxic-oxic-anoxic conditions, in a forebulge depozone (sensuDeCelles & Giles 1996), and consist of a pelitic background sporadically interrupted by coarse-grained events. During the Late Eocene the sedimentation registered a transition from calcareous (Doamna Limestones) to pelitic (Bisericani Beds) grading to Globigerina Marls at the Eocene-Oligocene boundary, and upward during the Oligocene in deposits rich in organic matter (Lower Menilites, Bituminous Marls, Lower and Upper Dysodilic Shales) with coarsegrained interlayers. Seven facies associations were recognized, and interpreted as depositional systems of shallow to deeper water on a ramp-type margin. Two mixed depositional systems of turbidite-like facies association separated by a thick pelitic interval (Bituminous Marls) have been recognized. They were supplied by a "green schists" source area of Central Dobrogea type. The petrography of the sandstone beds shows an excellent compositional uniformity (quartzarenite-like rocks), probably representing a first cycle detritus derived from low rank metamorphic sources, connected with the forebulge relief developed on such a basement. The sedimentation was controlled mainly by different subsidence of blocks created by extensional tectonic affecting the ramp-type margin of the forebulge depozone.

scholarly journals Are Large Particles of Iron Detrimental to Properties of Powder Metallurgy Steels?

Metals ◽  
2020 ◽  
Vol 10 (4) ◽  
pp. 431
Author(s):  
Ahmed Abdallah ◽  
Mahdi Habibnejad-Korayem ◽  
Dmitri V. Malakhov
Keyword(s):  
Powder Metallurgy ◽  
Apparent Density ◽  
Heavy Tail ◽  
Number Density ◽  
Iron Powders ◽  
Distribution Histogram ◽  
Compositional Uniformity ◽  
Large Particles ◽  
Size Distribution Histogram ◽  
Sintered Materials

It is experimentally shown that a removal of particles exceeding 100 microns in size from iron powders typically used in the fabrication of medium density powder metallurgy steels has a weak effect on apparent density, flowability and compressibility of blends as well as on density and strength of green bodies. An elimination of such particles, i.e., cutting off a heavy tail of a size distribution histogram at the 100 μm threshold, improves a compositional uniformity of sintered materials, but has no noticeable beneficial effect upon the strength of a final product, which is likely be determined by a fraction of pores and their shapes. A presence of soft pearlitic inclusions hardly matters unless their number density becomes so large that a 3D continuity (integrity) of a hard martensitic matrix is lost. This finding suggests that such an expensive preparatory step as sieving away large particles from as-received mixtures would bear no technological advantages. It was experimentally found that an attempt to lower the threshold below 100 μm noticeably worsened apparent density, flowability and compressibility.

Strain and misorientation in GaAs grown on Si(001) by organometallic epitaxy

1988 ◽  
Vol 53 (13) ◽  
pp. 1204-1206 ◽  
Author(s):  
S. K. Ghandhi ◽  
J. E. Ayers
Keyword(s):  
Organometallic Epitaxy

Compositional uniformity of a Si 0.5 Ge 0.5 crystal grown on board the International Space Station

2015 ◽  
Vol 419 ◽  
pp. 47-51 ◽  
Author(s):  
K. Kinoshita ◽  
Y. Arai ◽  
Y. Inatomi ◽  
T. Tsukada ◽  
H. Miyata ◽  
...  
Keyword(s):  
International Space Station ◽  
Space Station ◽  
International Space ◽  
Compositional Uniformity

High Quality Al-Ga-In-N Heterostructures Fabricated by MOVPE Growth in Multiwafer Reactors

1997 ◽  
Vol 2 ◽  
Author(s):  
D. Schmitz ◽  
R. Beccard ◽  
O. Schoen ◽  
R. Niebuhr ◽  
B. Wachtendorf ◽  
...  
Keyword(s):  
High Efficiency ◽  
Optical Quality ◽  
Efficient Production ◽  
Acceptor Doping ◽  
Thickness Uniformity ◽  
Si Doping ◽  
Compositional Uniformity ◽  
Wavelength Variation ◽  
Better Than

We present results on the growth of Al-Ga-In-N films in multiwafer reactors with 7×2″ wafer capacity. The design of these reactors allows the combination of high efficiency (TMGa efficiency for GaN around 30%) and excellent uniformity. Results on the growth of all materials from the Al-Ga-In-Nitride family are presented in detail. GaN is grown with an excellent optical quality and very good thickness uniformity below 2% across 2″ wafers. The material quality is shown by electron mobility of more than 500 cm2/Vs at an intentional Si-doping of approximately 1×1017 cm−3. Controlled acceptor doping with Mg yields carrier concentrations between 5×1016 and 1018 cm−3. The layer thickness uniformity of the films are better than 2% over a 2″ wafer area. GaInN is grown with PL emission wavelengths in the visible blue region showing a uniformity better than 1.5 nm standard deviation. The film thickness uniformity represents the same figures as obtained for the binary. The compositional uniformity of AlGaN is in the sub 1% range corresponding to a wavelength variation below 1 nm.The fabrication of heterostructures from these binary and ternary materials is described as well as results from the characterization of these structures. The results show that reliable and efficient production of Al-Ga-In-Nitride based optoelectronic devices can be performed in multiwafer reactors.

Effect of process conditions on the quality of CdTe grown on InSb by organometallic epitaxy

1986 ◽  
Vol 49 (19) ◽  
pp. 1290-1292 ◽  
Author(s):  
S. K. Ghandhi ◽  
N. R. Taskar ◽  
I. B. Bhat
Keyword(s):  
Process Conditions ◽  
Organometallic Epitaxy
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