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Topic: Crystallographic defects

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	Crystallographic defects: Definition and Links by Encyclopedian.com
		Crystallographic solids have an atomic structure which is very regular: that is, the local positions of atoms with respect to each other is repeated at the atomic scale.
		These arrangements are called crystal structures, the study of which is called crystallography However, most crystalline materials are not perfect: the regular pattern of atomic arrangement is interrupted by crystal defects.
		The analogy with a stack of paper is apt: if a half a piece of paper is inserted in a stack of paper, the defect in the stack is only noticeable at the edge of the half sheet.
	www.encyclopedian.com /cr/Crystallographic-defects.html (877 words)

	Crystallography - QuickSeek Encyclopedia (Site not responding. Last check: 2007-10-19)
		Crystallographic methods now rely on the analysis of the diffraction patterns that emerge from a sample that is targeted by a beam of some type.
		Crystallographers often explicitly state the type of illumination used when referring to a method, as with the terms X-ray diffraction, neutron diffraction and electron diffraction.
		Although many universities that engage in crystallographic research have their own X-ray producing equipment, Synchrotrons are often used as X-ray sources, because of the purer and more complete patterns such sources can generate.
	crystallographer.quickseek.com (1423 words)

	Crystal Growing K-12 Experiments for Lesson Plans & Science Fair Projects
		Some crystallographers consider the hexagonal crystal system not to be its own crystal system, but instead a part of the trigonal crystal system.
		The crystallographic point group or crystal class is the set of non-translational symmetry operations that leave the appearance of the crystal structure unchanged.
		Real crystals feature defects or irregularities in the ideal arrangements described above and it is these defects that critically determine many of the electrical and mechanical properties of real materials.
	www.juliantrubin.com /encyclopedia/chemistry/crystal.html (2408 words)

	Crystallographic defect - Wikipedia, the free encyclopedia
		Dislocations are linear defects around which some of the atoms of the crystal lattice are misaligned.
		The screw dislocation is more difficult to visualise, but basically comprises a structure in which a helical path is traced around the linear defect (dislocation line) by the atomic planes of atoms in the crystal lattice.
		Disinclinations are line defects corresponding to "adding" or "subtracting" an angle around a line.
	en.wikipedia.org /wiki/Crystallographic_defect (1066 words)

	Dissertation Defense, WMU Graduate College
		In type-II superconductors, magnetic flux pinning is caused by the inhomogeneities present in the materials in the form of impurities, or crystallographic defects, which prevent the motion of the quantized magnetic flux lines, or vortices.
		The dynamics of the magnetic vortices and their interaction with the defects is not yet completely understood and irradiation induced defects are extensively used in order to study this interaction.
		The presence of the different types, and densities of defects in the crystallographic structure yield a very reach and diverse magnetic phase diagram of high temperature materials.
	www.wmich.edu /~grad/dissertation/dis-archive/tobos.html (330 words)

	Crystallographic defects in diamond - Wikipedia, the free encyclopedia
		Crystallographic defects in the crystal lattice of diamond are common; they may be the result of extrinsic substitutional impurities, or intrinsic (interstitial and structural) anomalies.
		The material properties of diamond are affected by these defects and determine to which type a diamond is assigned; the most dramatic effects are on a diamond's color and semiconductivity, as explained by the band theory.
		C center defects consist of single substitutional nitrogen atoms in the diamond lattice that are spacially isolated.
	en.wikipedia.org /wiki/Crystallographic_defects_in_diamond (1964 words)

	Diamond treatment for passivating stress surface defects - Patent 5916456
		It is believed that a passive carbide layer is created at the stressed surface defects in the diamond passivating those defects and significantly lowering their reactivity to oxygen at elevated temperature, i.e.
		It is also possible to convert the carbide which remains at the surface defects, after removal of the layer, to another form, for example, an oxide or a nitride, to increase transmission of radiation such as IR radiation.
		The experiments have shown that the crystallographic defects (including grain boundaries) present in CVD diamond are etched by high temperature air.
	www.freepatentsonline.com /5916456.html (2806 words)

	Infrared Laser Scattering Defects in Silicon Heavily Doped With Boron
		It is well recognized that the crystallographic defects associated with oxygen precipitation in the bulk region of silicon wafers are important for the integrated circuit (IC) device manufacturing process because the bulk defects are effective gettering sites for metallic impurities.
		Control of relaxation-induced gettering utilizing the bulk defects as the gettering sites, on the other hand, is a complex process because the oxygen precipitation in highly doped silicon behaves in an anomalous manner during the multistep IC device annealing process [6-9].
		Even though defects having sizes of several hundred Å can be detected by IR laser scattering due to a large difference in the refractive index between silicon and the defect, inherent problems still exist, such as free-carrier absorption resulting from heavily doping in epitaxial substrate wafer [13].
	www.nmsresearch.com /TechnologyReviews/TECH002-081103.htm (999 words)

	Crystal Defects in Silicon - Page 1 of 3 - Point Defects, etc.
		The presence of most of these crystalline defects is undesirable in silicon wafers, although certain types of 'defects' are essential in semiconductor manufacturing.
		Aside from the formation of Schottky and Frenkel defects, there's a third mechanism by which an intrinsic point defect may be formed, i.e., the movement of a surface atom into an interstitial site.
		The presence of point defects is important in the kinetics of diffusion and oxidation.
	www.siliconfareast.com /crystaldefects.htm (407 words)

	Thursday Afternoon Sessions (June 27)
		Hydrogen passivation of defects at grain boundaries in polycrystalline silicon and of interface defects in MOS devices are well-known technological applications of hydrogenation, the adoption of which predates our understanding of the underlying microscopic processes.
		The defect at 0.37 eV is due to misfit defects introduced during growth since it is present in both the oxygen-doped and control samples.
		We present evidence that crystallographic defects in the active region are responsible for this "power slump" and that these defects originate during device operation due to the high strain fields which exist as the result of passivation layer processing.
	www.tms.org /Meetings/EMC96/thursT1.html (2831 words)

	research
		Through the investigation of growth defects, micro-crystallographic change to the crystal lattice related to impurity incorporation, local structure of impurity species incorporated in crystal, the surface growth mechanism and chemistry and the structure nature of impurity incorporation can possibly be determined.
		X-ray topography to determine single crystal defects in order to understand how the individual crystal surfaces have developed with respect to each other and how their growth has been mediated by lattice defects such as growth striations, dislocations, inclusions, etc.
		Molecular and crystallographic modelling, based on experimental study of impurity in crystal, to solve the structure associated with the impurity adsorption process and in crystal lattice.
	www.leeds.ac.uk /chemeng/STAFF/Lai/reseach.htm (312 words)

	Materials Science and Engineering
		Topics to be presented include elementary theory of metals, defects and related phenomena, soidification, phase phenomena, solid state diffusion, nucleation and growth kinetics, as well as transformation and deformation processes.
		Crystallographic defects in solids, namely point defects such as vacancies and interstitial, line defects such as dislocations, and planar defects such as grain boundaries.
		Correlation of these defects to the mechanical, electrical and optical behavior of materials is examined in particular.
	www.njit.edu /v2/archivecatalog/graduate/96/67.html (881 words)

	Crystalline Structures \| Crystal Lattice \| Crystal System
		The Cubic system has three crystallographic axes that are all perpendicular to each other and equal in length.
		The Hexagonal crystal system is has four crystallographic axes consisting of three equal horizontal or equatorial (a, b, and d) axes at 120º, and one vertical (c) axis that is perpendicular to the other three.
		The (a) and (c) crystallographic axes are inclined toward each other at an oblique angle, and the (b) axis is perpendicular to a and c.
	www.khulsey.com /jewelry/crystalline_structures.html (753 words)

	Device Failures due to Wafer Crystal Defects
		The presence of defects and electrically neutral impurities in the crystal decreases the minority carrier lifetime, since these defects and impurities tend to form recombination centers within the crystal that 'trap' active carriers.
		The interesting aspect of this issue is the fact that the collector-base and base-emitter leakage currents may remain at minimal levels, even while there is a marked increase in collector-emitter leakage.
		Higher gate oxide defect density, which also reduces the oxide's breakdown voltage, has also been correlated with the presence of oxygen precipitates at the wafer surface.
	www.siliconfareast.com /wafer-failures.htm (652 words)

	National Synchrotron Light Source
		The role of crystallographic defects on the performance of semiconductor devices has been studied using the example of pn junction diodes in the modern semiconductor compound silicon carbide.
		The correlation of the locations of crystallographic defects as observed by the Synchrotron White-beam X ray Diffraction Topography technique and the electrical characteristics of the electronic devices allows us to draw conclusions about the importance of high-quality semiconductor material for reliable device operation.
		The results showed a clear correlation between the presence of crystallographic defects and a reduced performance of the affected diodes.
	www.nsls.bnl.gov /newsroom/science/2003/07-zimmerman.htm (759 words)

	Crystal
		Most crystalline materials have a variety of crystallographic defects.
		The types and structures of these defects often control the properties of the materials.
		Some crystalline materials may exhibit special electrical properties such as the ferroelectric effect.
	www.ebroadcast.com.au /lookup/encyclopedia/cr/Crystal.html (243 words)

	Crystallography Summary
		Point defects include missing atoms or substituted atoms; line defects are defects that extend along straight or curved lines in a crystal; plane defects extend along true planes or curved surfaces within crystals.
		The next great crystallographer was the French mineralogist René-Just Haüy (1743-1822), who became involved in the science quite accidentally.
		Crystallographic methods now depend on the analysis of the diffraction patterns that emerge from a sample that is targeted by a beam of some type.
	www.bookrags.com /Crystallography (8757 words)

	Genetic Birth Defects
		in materials science, a crystallographic defect is a structural imperfection in a eugfcrystal.
		A bug, defect, error, are all examples of failures.
		Crystalline solids have a very regular atomic structure: that is, the local positions of atoms with respect to each other are repeated at the atomic scale.
	www.breadlike.com /pages7/35/genetic-birth-defects.html (727 words)

	Solid State Technology - Improving 300mm wafer yield using x-ray diffraction inspection
		Digital x-ray imaging for crystallographic defects has the potential to deliver substantial savings in a semiconductor manufacturing environment by identifying defects that may cause device failure or wafer breakage during ultra-fast annealing.
		However, defects that disturb the perfection of the lattice (i.e., those that introduce strain and/or tilt) alter the diffraction conditions, giving rise to variations in the diffracted intensity near the defects.
		Transmission geometry, on the other hand, is capable of identifying defects through the whole depth of the wafer, from the back side to the front surface, including the area under the bevel.
	sst.pennnet.com /articles/article_display.cfm?section=home&article_id=253398&version_num=3&p=5 (1071 words)

	Visualization of the first-order vortex-lattice melting transition
		This is an example of the melting process in a large BSCCO crystal, which has three visible crystallographic defects seen as three parallel inclined lines.
		This is another crystal that has a defect across the center of the sample with a small step in thickness.
		The lower boundary of the liquid expands with the field, however, the upper solid-liquid interface is fully pinned at the defect.
	www.weizmann.ac.il /home/fnsup/research-mo-visualiz.html (1250 words)

	1991 Published Proceeding Volumes
		This symposium focuses on the science and technology of chemical and crystallographic defects in silicon crystals and wafers.
		Among the defects of concern are oxygen, carbon, nitrogen, hydrogen, other electrically "inactive" impurities; heavy metals; vacancies; self-interstitials; dislocations; stacking faults; oxide or metallic precipitates; and near-surface damage.
		Topics include the origin of these defects; mechanical, chemical, and electrical effects of defects in the bulk or at the surface; interactions between two or more defect species; and techniques for characterizing and controlling defects.
	www.electrochem.org /dl/pv/published/1991/1991.htm (831 words)

	Transene - Etchants
		For characterization and identification of crystallographic defects in semiconductors.
		The effectiveness of Wright Etchant and AB Etchant permits superior delineation of crystal defects.
		Defect delineation etchants reveal crystal dislocations, striations, slip lines, and faults.
	www.transene.com /wright.html (168 words)

	Crystallographic defects in CoCrPt thin film media
		Crystallographic defects in CoCrPt thin film media: effect on interactions and magnetic viscosity
		We propose that this is due to the reduction in the anisotropy fields caused by the crystallographic defects which then allows exchange coupling to dominate the reversal, causing cooperative reversal.
		We have also investigated the degree of in- and out-of-plane c-axis texture in the films and find that this is also dependent on the level of nitrogen contamination, as the c-axis texture is very poor in the film grown in the worst vacuum conditions.
	stacks.iop.org /0022-3727/35/512 (447 words)

	Contactless LSI junction leakage testing method - Patent 4015203
		Production yield in high density large scale integration transistor processing is adversely effected by the presence of crystallographic defects which create "pipes" or undesired pathways between collector and emitter along which impurities diffuse to produce collector to emitter leakage resistance.
		It is important that such crystallographic defects be detected at an early stage before completion of LSI transistor devices to minimize any production investment in unacceptable devices.
		A semiconductor PN junction may be represented by the equivalent circuit consisting of three elements connected in parallel with each other, i.e., a capacitor representing junction capacitance, a diode representing the rectification properties of the junction, and a resistor representing the leakage resistance of the junction.
	www.freepatentsonline.com /4015203.html (3344 words)

	Control of Microstructural Features, Page 2
		In this paper we will emphasize the role that underlayers and interlayers play in the development of the crystallographic texture and grain size of thin magnetic films and only briefly discuss the role of the other process variables.
		In order to produce a thin film of a cobalt based alloy (hcp, P6 /mmc) with its c axes in or near the plane of the film, an underlayer must be used (1-9).
		It should be noted that it is the structure which determines the crystallographic growth texture, not the Bravais Lattice (10).
	neon.mems.cmu.edu /laughlin/pdf/180/p1-2.html (342 words)

	X-Ray Tool detects defects in semiconductor wafers., Bede
		Defect mapping tool uses non-destructive X-ray diffraction to identify anomalies in incoming and processed wafers and delivers quantitative data that enables in-line statistical control of manufacturing processes.
		A revolutionary defect mapping tool, BedeScan uses non-destructive X-ray diffraction (XRD) to identify a wide range of anomalies in both incoming and processed wafers, including thermal slip dislocations, edge damage, and other crystallographic defects.
		A versatile tool, BedeScan allows for imaging of wafers in both reflection and transmission modes, providing information about crystallographic defects in the surface region and bulk of wafers.
	news.thomasnet.com /fullstory/464059 (504 words)

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