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Topic: Charge carriers

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	Tensen Physics Dictionary (C)
		The word "charge" is generally used to denote electrical charge, but it may also refer to gravitational charge (usually called mass), to weak charge, or to color charge.
		charge carrier, negative: A negative charge carrier is an electron which is in the conduction band, the flow of which explicitly creates the electrical current.
		The conduction of the charge carriers is the electrical current.
	www.mcm.edu /~christej/dictionary/dictC.html (880 words)

	oe magazine - tutorial - photodiodes see the light (Site not responding. Last check: 2007-11-03)
		Charge carriers diffuse across the pn junction (diffusive force) driven by a concentration gradient that produces an internal electrical field across the junction.
		In a p-i-n photodiode, charge carriers produced by photon absorption are swept across the junction by the internal (and any external) voltage bias, which produces a small photocurrent at the electrodes.
		Charge carriers created outside the depletion region will move randomly, many of them eventually entering the depletion region to be swept rapidly across the junction.
	oemagazine.com /fromTheMagazine/aug01/tutorial.html (1596 words)

	Energy conversion system - Patent 4772816
		This charges the target electrode (10), and the increased energy is extracted from the apparatus by connecting an electrical load between the target electrode and a point of lower or higher potential.
		A process according to claim 1 in which the generated electric potential is directly or indirectly used to maintain the generation of charge carriers and the internal temperature of the space traversed by the magnetic field and the applied magnetic field.
		For an electron carrying a charge e, and moving at a speed v over distance d, the total force on the electron is the centripetal force.SIGMA.H.e.v, less the force exerted on the electron in the opposite direction by the centrifugal force, which is.SIGMA.mv.sup.2 r.sup.-1.
	www.freepatentsonline.com /4772816.html (3704 words)

	Electric current
		Electric current is the rate of charge flow past a given point in an electric circuit, measured in coulombs/second which is named amperes.
		The influence of charges is characterized in terms of the forces between them (Coulomb's law) and the electric field and voltage produced by them.
		Although it is electrons which are the mobile charge carriers which are responsible for electric current in conductors such as wires, it has long been the convention to take the direction of electric current as if it were the positive charges which are moving.
	hyperphysics.phy-astr.gsu.edu /hbase/electric/elecur.html (698 words)

	Charge carrier - Wikipedia, the free encyclopedia
		Charge carrier denotes in physics a free (mobile, unbound) particle carrying an electric charge.
		In semiconductor physics, the travelling vacancies in the valence-band electron population (holes) are treated as charge carriers.
		In metals, the charge carriers are the electrons forming the Fermi gas in the metal lattice.
	en.wikipedia.org /wiki/Charge_carrier (301 words)

	ORTEC - Semiconductor Radiation Detectors
		The charge carriers created by the ionizing radiation drift to the contacts of opposite polarity, following the lines of force of the electric field established by the applied voltage.
		Trapping of a charge carrier in a semiconductor occurs when the carrier is captured by an impurity or imperfection center and is temporarily lost to any charge transport process.
		This phenomenon is unimportant in the detection of light particles, gamma, or x rays because the probability of carrier recombination in a semiconductor region with a high electric field is negligible.
	www.ortec-online.com /detectors/review_physics/pulse.htm (1200 words)

	Thermoelectrics By Tellurex Corporation
		Charge carriers are the physical components of a material which allow it to conduct electricity.
		With differing capacities for moving charge carriers in response to thermal flow, the current level in one conductor will overcome (or in some cases, complement) the potential for thermally-generated current flow in the other conductor.
		As the heat moves from the hot to the cold side of the pellet, the charge carriers (i.e., electrons from the dopants) are carried with the heat.
	www.tellurex.com /12most2.html (2011 words)

	How Fast Does a Charge Decay?
		The field from a given charge will always be proportional to the charge, but the factor of proportionality will depend upon the geometry and dielectric properties of the charged body and its surroundings.
		However, part of the flux from the charge will run in the adjoining layers, and the "driving field," that is, the field in the conductive layer, will depend upon the permittive properties of the adjoining insulators.
		The sample is allegedly charged by the electrodes when they are connected to a voltage supply, and the charge decay is taken as the reading of the field meter after the electrodes are grounded.
	www.ce-mag.com /archive/2000/marapril/mrstatic.html (2119 words)

	[No title]
		When a photon of light is absorbed, it excites an electron and produces a single pair of charge carriers, an electron and a hole, where a hole is simply the absence of an electron in the semiconductor lattice.
		Because charge carriers cannot reside in this region, it is termed the “depletion region.” A generic pin photodiode is shown schematically in Figure 2.
		This movement of charge carriers across the junction upsets the electrical balance and produces a small photocurrent, which can be detected at the electrodes, as shown in Figure 2.
	www.advancedphotonix.com /word_docs/PRIMER_OE_Magazine_.doc (1433 words)

	The p-n Junction Diode
		The positive charge carriers actually correspond to vacancies or deficiencies of electrons in the bonds holding the atoms in the crystal lattice.
		There is then a separation of charges: negative fixed charges on the p-type side of the depletion layer and positive fixed charges on the n-type side.
		Remembering that the built-in potential opposes the flow of majority carriers across the junction, a reduction in that potential makes it easier for holes in the p-type region to cross the junction and for electrons in the n-type region to cross the junction in the opposite direction.
	library.thinkquest.org /12666/junction.html (2386 words)

	Charge transport in polar crystals and holographic time of flight
		We exploit the fact that any movement of the photoexcited charge carriers away from their photoexcitation place is a displacement of charge that leads to an electric field.
		It is the refractive index modulation induced by this electric field that allows us to detect (by diffraction of an optical wave) how fast the charge carriers move and consequently determine their mobility, or the free carrier lifetime.
		We are currently applying this method to the fundamental investigation of charge transport in polar inorganic and organic crystals where the mobility is limited by formation of polarons and by a small overlap between electronic states.
	www.lehigh.edu /~inlo/htof.html (311 words)

	charge quantity - a definition from Whatis.com
		Charge quantity is an expression of the extent to which an object is electrically charged.
		For any two charged bodies, the force decreases in proportion to the square of the distance between their charge centers, assuming the charges on the objects do not change.
		A unit electric charge is the charge quantity contained in a single electron or proton.
	whatis.techtarget.com /definition/0,,sid9_gci550477,00.html (286 words)

	Charge density - Wikipedia, the free encyclopedia
		The charge density is the amount of electric charge in a volume.
		It should not be confused with the charge carrier density.
		The charge density appears in the continuity equation which follows from Maxwell's Equations in the electromagnetic theory.
	en.wikipedia.org /wiki/Charge_density (277 words)

	Charge -- from Eric Weisstein's World of Physics
		The MKS unit of charge is the Coulomb, while the cgs unit is the electrostatic unit, or esu.
		The smallest measurable unit of charge is that carried by the electron,
		chose to call "positive" the charge opposite that carried by the usual charge carriers (i.e., electrons).
	scienceworld.wolfram.com /physics/Charge.html (107 words)

	Current in a Wire
		Current is a measure of the rate at which charge is flowing past some point in a wire.
		In a wire, collisions of the conduction charges with impurities, imperfections, and vibrations of the atomic lattice causes the motion of the conduction charges to be slowed down.
		The current in a wire can be expressed as function of the number of charge carriers/volume, the magnitude of the charge carriers, the drift velocity of the charge carriers, and the cross-sectional are of the wire,
	www.ac.wwu.edu /~vawter/PhysicsNet/Topics/DC-Current/Current.html (385 words)

	Regulatory Commission of Alaska - Phone Bill Charges
		One flat monthly charge may be shown for all local service furnished under the same telephone number, and this charge may be billed one month in advance.
		All toll charges must be itemized, specifying on a call-by-call basis the date of the call, the locations connected, the duration of the call, whether the call required special assistance (e.g., person-to-person, operated assisted, etc.), and the charge for the call.
		The Alaska ’s TRS carrier is South Dakota Association of the Deaf d/b/a Alaska Relay, CSD of Alaska.
	www.state.ak.us /rca/Consumer/PhoneCharges.html (1288 words)

	Hardware Analysis - Semiconductor Physics, Part 2 - Charge Carriers, Understanding Conduction
		Space charge neutrality is the idea that a sample of material will always contain the same total amount of charge, or in other words, the same number of electrons (remember that protons cannot move, so the only way to change the amount of charge in a substance is to add or remove electrons).
		The one that emerged from the other end is not the same one we pushed in, thus we can picture the idea of free electrons as charge carriers in a chain, that are free to be pushed along from one end or another by other charge carriers.
		This is an example of an open circuit, a gap in the loop preventing charge carriers from moving, thus preventing current.
	www.hardwareanalysis.com /content/article/1588.2 (618 words)

	Hardware Analysis - Semiconductor Physics, Part 2 - Excess Charge Carriers
		Now that we know that conductivity relates to free charge carriers, we can change that statement slightly, to say that they’re useful because we can easily and significantly alter the number of charge carriers available.
		We saw two means of increasing charge carriers in Part 1, namely Thermal Generation and Optical Generation.
		So keeping the device around room temperature would ensure that we always had a certain number of charge carriers available, but for pure intrinsic silicon, as we’ve been considering, the number of charge carriers available due to thermal excitation, even well above room temperature, is minimal.
	www.hardwareanalysis.com /content/article/1588.4 (632 words)

	Probing Organic Transistors with Infrared Beams
		In FETs, the charge carriers are confined to a nanometer-thick layer at the semiconductor–insulator interface, buried under several layers of the device.
		In addition, when these charges are displaced under the influence of an electric field, they drag the local polarization cloud of the molecular chains with them, forming so-called polarons.
		The variation of carrier density away from the injection contacts in the area shown by the blue square in the figure at top, obtained by spatially monitoring the spectroscopic fingerprints of the injected charges using infrared microspectroscopy.
	www-als.lbl.gov /als/science/sci_archive/127transistor.html (1045 words)

	Lab 3 (Site not responding. Last check: 2007-11-03)
		Semiconductors such as silicon require doping with impurity atoms from columns III and V of the periodic table to increase the number of charge carriers at room temperature to an acceptable level.
		Both the electrons and the holes are now charge carriers and will migrate (in opposite directions) under the influence of an electric field.
		Since the conductivity is limited by an insufficient numbers of carriers, a larger number of carriers serves to increase the conductivity as temperature goes up.
	mot.vuse.vanderbilt.edu /mse150/lab_3.htm (1498 words)

	hole - a definition from Whatis.com
		In physics, a hole is an electric charge carrier with a positive charge, equal in magnitude but opposite in polarity to the charge on the electron.
		Holes and electrons are the two types of charge carriers responsible for current in semiconductor materials.
		In the processing of semiconductors, the number of charge carriers can be increased by a process known as doping, which consists of adding minute amounts of elements called impurities.
	whatis.techtarget.com /definition/0,,sid9_gci214516,00.html (349 words)

	Fractional charge carriers discovered (October 1997) - News - PhysicsWeb
		Electric charge normally comes in an indivisible unit: the charge of an electron.
		Fluctuations in the current - shot noise - were used to measure the electrical charge of the carrier particles.
		By analysing the shot noise in this regime, both groups reported evidence that the electric current is carried by quanta with charge one-third that of the electron.
	physicsweb.org /article/news/1/10/7/1 (379 words)

	Science/AAAS \| Editors' Choice : 28 October 2005; 310 (5748)
		The study of recolonization and succession after catastrophic disturbance can offer insights into the rules governing the assembly of ecological communities and how species interact during colonization and invasion, as well as the speed and trajectory of recovery.
		The performance of electronic devices such as thin-film transistors or semiconductor-based light-emitting diodes depends crucially on the dynamics and spatial distribution of the carriers throughout the device.
		In the case of light-emitting diodes, carriers can be lost because of both radiative and nonradiative recombination.
	www.sciencemag.org /content/vol310/issue5748/twil.dtl (1313 words)

	Increasing charge mobility in single molecular organic crystals
		To find out which materials have the best potential for carrying current, Butko has been studying single crystals of molecular organic materials such as pentacene and rubrene.
		The key, says Butko, is to know whether the injected charge carriers will have a high mobility or stay localized.
		At these low temperatures the mobility edge can be probed without the complication of thermal activation -- a process that assists charge carrier transport in semiconductors due to large thermal energy at high temperatures.
	www.eurekalert.org /pub_releases/2005-03/dnl-icm031405.php (627 words)

	INCREASING CHARGE MOBILITY IN SINGLE MOLECULAR ORGANIC CRYSTALS
		At these low temperatures the mobility edge can be probed without the complication of thermal activation - a process that assists charge carrier transport in semiconductors due to large thermal energy at high temperatures.
		To carry out basic and applied research in long-term, high-risk programs at the frontier of science.
		To disseminate technical knowledge, to educate new generations of scientists and engineers, to maintain technical capabilities in the nation's workforce, and to encourage scientific awareness in the general public.
	www.newmaterials.com /news/2225.asp (618 words)

	Regulatory Commission of Alaska Telecommunications-Network Access Fee
		This pass-through of access charge costs from the local telephone company to the long distance company to the consumer\ generally prevents Alaska’s long distance carriers from charging less than 14 cents per minute for an in-state call.
		In the first year of the program, the reduction on access charge rates paid by the largest long distance carriers will be about two cents per minute on a typical in-state call.
		The federal subscriber line charge is currently capped at $6.50 per line for residential service and single line business service and $9.20 per line for multiple line business service.
	www.state.ak.us /rca/Telecom/naf (1721 words)

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