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	Indirect bandgap - Wikipedia, the free encyclopedia
		In semiconductor physics, an indirect bandgap is a bandgap in which the minimum energy in the conduction band is shifted by a k-vector, which is determined by the material's crystal structure.
		Semiconductors with an indirect bandgap are inefficient at emitting light.
		Silicon is an indirect bandgap semiconductor, and hence is not generally useful for light-emitting diodes or laser diodes.
	en.wikipedia.org /wiki/Indirect_bandgap (215 words)

	Direct bandgap -- Facts, Info, and Encyclopedia article (Site not responding. Last check: 2007-11-05)
		A semiconductor with a direct bandgap can be used to emit light.
		Indirect bandgap semiconductors such as (Click link for more info and facts about crystalline silicon) crystalline silicon cannot do so efficiently.
		The prime example of a direct bandgap semiconductor is (Click link for more info and facts about gallium arsenide) gallium arsenide - a material commonly used in (Click link for more info and facts about laser diode) laser diodes.
	www.absoluteastronomy.com /encyclopedia/d/di/direct_bandgap.htm (105 words)

	Researchers Create Tunable Photonic Bandgap Crystal: Photonics Technology News January 2000
		Semiconductor materials with electronic bandgaps -- electron energies that are forbidden within the crystal -- were the cornerstone of the electronics revolution.
		The liquid crystal reduces the bandgap to 1.6 percent, but it can now be completely closed via an external magnetic field.
		The tunable bandgap could be used not only for simple on/off switching, but also for more localized control of the propagation.
	www.physics.utoronto.ca /~john/techCrystal.html (491 words)

	Photonic Bandgap Fiber Eyed for Telecommunications - April, 2004 (Site not responding. Last check: 2007-11-05)
		In a close analogy to the electronic bandgap in a semiconductor, a photonic bandgap occurs in a periodic optical material when the periodicity prohibits solutions to Maxwell's equations for certain wavelengths.
		A photonic bandgap fiber consists of a hollow core surrounded by a cladding whose periodicity creates a bandgap for the photons guided in the fiber's core (Figure 1).
		Photonic bandgap fibers are of intense interest for telecom applications because their optical characteristics -- e.g., birefringence and dispersion -- can be tailored readily by fiber design, and because they have the potential to have lower loss than conventional glass fiber.
	www.photonics.com /spectra/research/XQ/ASP/preaid.177/QX/read.htm (634 words)

	Design
		bandgap in Mosis 0.18 micron process was to determine the resistor values required to case the output voltage to minimize temperature independence.
		The spike on the graph of N4 is startup circuit energizing the bandgap.
		The layout of a bandgap is more demanding than that of say a digital core.
	www.qsl.net /kb9jzp/ICDesign.htm (587 words)

	World Intellectual Property Organization (Site not responding. Last check: 2007-11-05)
		The operation of the photodetector in reverse bias mode is similar to that previously described in connection with figures 2a and 2d, although the photodetector of course is positioned at or close to the peak of the optical field distribution 1 in the principal optical path.
		This enables the photodetector contact 22,31, 35 to be used to inject carriers (using a forward bias mode of operation) into the bandgap shifted/non-shifted regions of the device to monitor the effectiveness of the intermixing process used to create the bandgap shift.
		The device of claim 1 further including at least one bandgap shifted region in the optical path, having a larger band gap than in the optically active region, in which the second contact is positioned at least partly over the bandgap shifted region.
	www.wipo.int /ipdl/IPDL-CIMAGES/view/pct/getbykey5?KEY=03/88367.031023&ELEMENT_SET=DECL (3807 words)

	Photonic Bandgap Fiber Makes Unique Gas Sensor - November, 2004 (Site not responding. Last check: 2007-11-05)
		Photonic crystal and photonic bandgap fibers are both members of the family of microstructured fibers or, as they are known colloquially, holey fibers.
		In a photonic bandgap fiber, however, the periodicity of the airholes in the cladding creates a region in which photons of given energy cannot exist, so light is guided in the core because it cannot exist in the cladding.
		The physics of a photonic bandgap fiber is analogous to that of a semiconductor, in which the crystal periodicity creates a region where electrons of given energy cannot exist.
	www.photonics.com /spectra/research/XQ/ASP/preaid.208/QX/read.htm (657 words)

	Bandgap of indium nitride measured as 0.7 eV (November 2002) - News - Compound Semiconductor
		Bandgap of indium nitride measured as 0.7 eV
		It was found that the bandgap of InGaN decreased with increasing In content, from 3.4 eV for pure GaN to 0.7 eV for InN.
		The bandgap of 0.7 eV for InN is equivalent to a wavelength of around 1.77 microns.
	www.compoundsemiconductor.net /articles/news/6/11/17/1 (445 words)

	Semiconductor - Wikipedia, the free encyclopedia
		In the parlance of solid-state physics, semiconductors (and insulators) are defined as solids in which at absolute zero (0 K), the uppermost band of occupied electron energy states, known as the valence band, is completely full.
		The ease with which electrons in a semiconductor can be excited from the valence band to the conduction band depends on the band gap between the bands, and it is the size of this energy bandgap that serves as an arbitrary dividing line between semiconductors and insulators.
		Materials with a bandgap energy of less than about 3 electronvolts (eV) are generally considered semiconductors, while those with a greater bandgap energy are considered insulators..
	en.wikipedia.org /wiki/Semiconductor (1944 words)

	Use of chemical-mechanical polishing for fabricating photonic bandgap structures (US5998298)
		The use of chemical-mechanical planarization allows the photonic bandgap structure to be formed over a large area with a layer uniformity of about two-percent.
		Air-gap photonic bandgap structures can also be formed by removing a spacer material separating the arrayed elements by selective etching.
		The method is useful for fabricating photonic bandgap structures including Fabry-Perot resonators and optical filters for use at wavelengths in the range of about 0.2-20 mu m.
	www.delphion.com /details?&pn=US05998298__ (452 words)

	Efficient broadband antenna system using photonic bandgap crystals (US5541613)
		The multiple crystals are attached together to form a photonic bandgap substrate whose bandwidth varies as a function of location on the substrate.
		A broadband antenna that can cover a wide frequency range, and whose active region shifts to different portions of the antenna as a function of frequency, is formed on the substrate such that the active region of the antenna is always on a crystal that has a corresponding operating bandwidth.
		The photonic bandgap crystals provide a nearly 100 percent efficient reflector for radiation emitted into the substrate that would otherwise be trapped or dissipated therein.
	www.delphion.com /details?&pn=US05541613__ (415 words)

	Solar Energy Technologies Program: Bandgap Energies of Semiconductors and Light
		This level of energy, known as the "bandgap energy," is the amount of energy required to dislodge an electron from its covalent bond and allow it to become part of an electrical circuit.
		To free an electron, the energy of a photon must be at least as great as the bandgap energy.
		Most PV cells cannot use about 55% of the energy of sunlight, because this energy is either below the bandgap of the material or carries excess energy.
	www.eere.energy.gov /solar/bandgap_energies.html?print (375 words)

	Inside-out gem channels light TRN 120501
		The dream for photonic bandgap materials is that manipulation of the photonic bandgap will lead to a similar revolution in photonics," said David Norris, a researcher at NEC research.
		Photonic bandgap crystals could also eventually be used to make all the components of a computer chip, which would make them much faster than today's electronic versions.
		But to make a photonic bandgap opal, the researchers inverted the gemstone process, replacing the spheres with space and the gaps between the spheres with silicon.
	www.trnmag.com /Stories/2001/120501/Inside-out_gem_channels_light_120501.html (925 words)

	Beta Compensation Complicates Bandgap Startup (Site not responding. Last check: 2007-11-05)
		The bandgap circuit shown in figure 1 produces a voltage that is stable with temperature[1].
		form a feedback path that stablizes the bandgap voltage and provides an output voltage that is a multiple of the bandgap voltage.
		Bandgaps produce a reference voltage to the first order, independent of temperature and supply voltage.
	www.ele.uri.edu /Courses/ele535/startup.kills (406 words)

	Pressure Dependence
		Recently InN was found to have a narrow fundamental bandgap of 0.7 eV [1-3] instead of the previously believed 1.9 eV.
		The hydrostatic pressure dependence of the fundamental bandgap is studied by the blue shifts of the optical absorption edge in a diamond anvil cell (Figure 1).
		The fundamental bandgap is determined by extrapolating the base line and the absorption edge.
	www.mse.berkeley.edu /~xli/SLi_Homepage/P_dep.htm (681 words)

	New twist for photonic bandgap crystals (May 2001) - News - optics.org
		Physicists Sajeev John and Ovidiu Toader at the University of Toronto in Canada say that they have created a blueprint of a three-dimensional photonic bandgap crystal that opens a new door for the development of all-optical devices.
		Their chiral crystal architecture should result in a material that has a large photonic bandgap in three dimensions and that is easy and affordable to produce.
		The physicists' calculations suggest that the structure will have a photonic bandgap between the fourth and fifth bands of the photon dispersion relation that is very robust to variations in the crystal's geometrical parameters.
	optics.org /articles/news/7/5/17/1 (356 words)

	Ragan, Regina (2002-01-16) Direct energy bandgap group IV alloys and nanostructures. ...
		Deformation potential theory calculations were performed to predict the effect of coherency strain on the extrema points of the conduction band and the valence band.
		Coherency strain did not change the SnxGe1-x energy bandgap when the strain axis was along [001] but deformation potential theory predicted the absence of an indirect to direct energy bandgap transition when the strain axis was along [111].
		A high degree of tunability of the bandgap energy with the quantum dot radius is expected for a-Sn.
	etd.caltech.edu /etd/available/etd-02142002-211940 (488 words)

	[No title] (Site not responding. Last check: 2007-11-05)
		Bandgap Voltage Reference Bandgap reference circuit is one where uses two quantities with opposite temperature coefficients are added with a proper weighing factor to result in a zero temperature coefficient.
		Bandgap terminology a) Bandgap Voltage Bandgap voltage of a semiconductor measured in eV refers to the potential difference between the valence band and the conduction band for that semiconductor.
		Bandgap reference principle Most of the modern bandgap reference circuits are made on the Paul Brokaw school of thought.
	www.rit.edu /~aad1943/Thesis.doc (2102 words)

	Circuit Sage: Bandgap Tools and Links
		Choppered CMOS Bandgap Reference, A good article, which talks about bandgap variance and noise.
		Effect of Ground Drop on Bandgaps, by Jim Daly: a case for routing bandgap currents and Kelvin connections.
		The making of a bandgap reference, an interesting tutorial on how to design a bipolar bandgap.
	www.circuitsage.com /bandgap.html (354 words)

	Semiconductor's Bandgap (Site not responding. Last check: 2007-11-05)
		A larger bandgap means the electron releases a more energetic photon of light.
		Kenneth Mellendorf ========================================================= The bandgap is the amount of energy required to raise a valence band electron into the conduction band.
		Conversely, it is the minimum amount of energy released when an electron moves directly from the conduction band to the valence band.
	www.newton.dep.anl.gov /askasci/phy00/phy00226.htm (201 words)

	BG001 - Untrimmed Precision Bandgap Voltage/Current Reference
		The BG001 is a low deviation Darlington Bandgap that uses stacked PNP bipolar transistors, low offset opamps, and matched polysilicon resistors to get high accuracy without using trim or dynamic techniques.
		(1) Although the bandgap may be implemented in any of the C5x processes, it should be noted that due to differences in sheet resistance between single polysilicon, double polysilicon, and high resistivity polysilicon processes, the bandgap output voltage may shift and will need to be recentered.
		Two of the most common questions regarding Bandgap performance are “what is the tolerance” and “what is the temperature Coefficient?” There are two important things to consider when talking about bandgap tolerance.
	www.amis.com /tech_resources/tech_docs/featuresheets/bg001 (640 words)

	Bandgap Encyclopedia Article, Definition, History, Biography (Site not responding. Last check: 2007-11-05)
		Find bandgap - Your relevant result is a click away!
		In solid state physics and related applied fields, the band gap is the energy difference between the top of the valence band and the bottom of the conduction band in insulators and semiconductors.
		Special purpose temperature-sensor integrated circuits such as the DS1621 exploit this property to provide electronic temperature readings.
	encyclopedia.localcolorart.com /encyclopedia/Bandgap (475 words)

	KTH in your Pocket: Implantation technology for wide bandgap semiconductors
		For electronic devices it is currently the high frequency, high power and high temperature applications that are of interest, but one can also envision novel electronic or opto-electronic device concepts based on hetero junctions and/or combinations with today's technology.
		The access to high-quality wide bandgap material has for long been restricted, but recent progress in the growth of for instance silicon carbide (SiC), gallium nitride (GaN) and also diamond (C), the ultimate wide bandgap semiconductor, has now made these materials available for device research.
		The ion implantation technology has been extremely successful for silicon technology and helped to push this material to be the number one semiconductor material today, but for the more complex wide bandgap materials the damage created by the implantation process limits the usefulness of this doping technology.
	www.kth.se /forskning/pocket/project.asp?id=12442 (261 words)

	INTRINSIC Semiconductor. Silicon carbide (SiC) wafers, substrates, GaN epitaxy (Site not responding. Last check: 2007-11-05)
		DULLES, VA – August 4, 2004 – INTRINSIC Semiconductor, a privately held manufacturer of wide bandgap materials, today announced that it is has entered into a definitive agreement to acquire Bandgap Technologies, Inc. (Columbia, SC).
		Bandgap Technologies is a defense contractor and a manufacturer of silicon carbide (SiC) wafer products.
		Bandgap Technologies, founded in 2000, has developed proprietary technology for producing the highest quality SiC wafers.
	www.intrinsicsemi.com /home02_aug04.html (273 words)

	Optical dispersive device based on photonic bandgap... (Site not responding. Last check: 2007-11-05)
		A new optical micro-structure which has highly dispersive properties and can thus be used to multiplex or demultiplex light for optical communications applications.
		It is a planar device and shares advantages of the so-called photonic bandgap "superprism" in that it is more compact than arrayed waveguide gratings and is also not limited by multiple diffraction orders.
		However, it is superior to currently disclosed superprism designs in that it is more amenable to available fabrication techniques and should display greatly reduced scattering loss.
	www.mcgill.ca /ott/technologies/pureappsci/04010 (218 words)

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