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Topic: Photoconductivity

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	Photoconductive member having an amorphous silicon layer - Patent 4501807
		A photoconductive member according to claim 1, wherein the state of distribution of the atoms (A) is uniform in the direction of the layer thickness.
		A photoconductive member according to claim 14, wherein the relation between the layer thickness T.sub.0 of the amorphous layer and the layer thickness t.sub.B of the second layer region is t.sub.B /T.sub.0.ltoreq.0.4.
		In the photoconductive member according to the present invention, improvements of higher dark resistance and better adhesion between the amorphous layer and the support on which it is directly provided or between the amorphous layer or other layers are intended preponderantly by incorporation of oxygen atoms in the first layer region (O).
	www.freepatentsonline.com /4501807.html (11581 words)

	Photoconductive membrane for exhibiting photoconductivity upon illumination by electromagnetic light in the visible to ...
		Therefore, when a photoconductive layer is formed of such a material and has so great a film thickness, as that found in a photosensitive member, light having a long wavelength may be absorbed by a portion near the base of the photoconductive layer.
		In the second layer (the second blocking layer or the first photoconductive layer) formed on the first layer, at least one of the elements of Group III or V of the Periodic Table is lightly doped, and the second layer is an intrinsic (i-type) semiconductor layer.
		A first photoconductive layer 16 is stacked on the layer 14 and has a thickness of 5.mu.m to 60.mu.m, and comprises a-Si:N or a-Si:C containing a Group III element in an amount falling within the range between 1.0.times.10.sup..times.8 atomic % and 1.0.times.10.sup.-4 atomic %.
	www.freepatentsonline.com /4724193.html (4554 words)

	2003 Building Publications - Photoconductivity Technique for the Assessment of Pigment Photoreactivity. (Site not responding. Last check: 2007-10-08)
		The primary objective of this research is to develop a standardized technique for the measurement of photoreactivity, one with a scientific basis that would provide the most direct correlation to end-use performance.
		One such technique involves measuring the photoconductivity of the pigments under ultraviolet (UV) irradiation.
		A prototype photoconductivity testing device and preliminary results from a variety of TiO2 systems will be presented.
	fire.nist.gov /bfrlpubs/build03/art044.html (232 words)

	Science.lt
		By using the presented methodology, photoconductivity is determined as the value proportional to the derivative of the photoelectric response signal.
		Photoconductivity according to the model exponentially decays because of the equilibration of the proton fluxes between both states separated by an energy barrier.
		We conclude that the negative part of the photoresponse signal of the samples of oriented PMs results from the polarization of the surrounding of the retinal and not from the proton transfer, while the slower positive part of the kinetics is caused by the proton transfer.
	www.fi.lt /science/anketa.php?id=169&lg= (274 words)

	photoconductivity - a Whatis.com definition
		Photoconductivity is the tendency of a substance to conduct electricity to an extent that depends on the intensity of light-radiant energy (usually infrared transmission or visible light) striking the surface of a sample.
		When there is no illumination, a photoconductive sample has a conductance that depends on its dimensions, on the specific material(s) from which it is made, and on the temperature.
		Photoconductive materials are used in the manufacture of photoelectric devices.
	whatis.techtarget.com /gDefinition/0,294236,sid44_gci213704,00.html (182 words)

	Integrated opto-electronic relay using a semiconductor with persistent photoconductivity and a matrix of such relays - ...
		Finally, the heating of the photoconductive layer, as a result of which it is possible to eliminate the conductivity of the material, can only be obtained by a means separate from that of the ultraviolet source.
		The photoconductive layer is deposited on one of the faces of a substrate 12 constituted by a semiconductor material which is made insulating (e.g.
		In this drawing, each photoconductive layer 10 is in contact by its upper face with a metal band 40 and by its lower face with a conductive band 42 obtained by ion implantation of GaAs in the substrate in order to make it conductive.
	www.freepatentsonline.com /4412235.html (1446 words)

	Method of electronic processing of exposed photographic material - Patent 4788131
		Use of radiofrequency photoconductivity apparatus for detection of the presence or absence of a latent image following a pulsed, high intensity, relatively longer wavelength radiation exposure of the photographic material provides enhanced sensitivity measurement utilizing lower frequency fields of high intensity radiation in comparison with microwave photoconductivity measurements mentioned in the prior art.
		Measurement of photoconductivity in an exposed photographic element is accomplished at reduced temperatures.
		2 illustrates a photoconductive measurement apparatus 1 comprising a radiofrequency oscillator 2 and a radiofrequency bridge 3.
	www.freepatentsonline.com /4788131.html (2907 words)

	Advanced Method of Transient Microwave Photoconductivity (AMTMP)
		The first due to the change in the bandwidth is known as a photoconductivity and usually is related to a change in the imaginary part of dielectric constant.
		The second due to the shift of the resonance frequency is known as a photodielectric effect and usually is related to a change in the real part of dielectric constant.
		This distinction is of great importance because in the first case the kinetics gives the true lifetime but in the second the observed time constant is related to the rate of release from traps present.
	www.chembio.uoguelph.ca /serguei/AMTMP.HTM (972 words)

	Photoconductivity of Single Carbon Nanotubes (Site not responding. Last check: 2007-10-08)
		In conclusion, we have measured the photoconductivity of individual carbon nanotubes, which act as the channel of a FET, upon infrared laser illumination.
		From the wavelength and polarization dependence of the photocurrent, we identified that the mechanism of photocurrent generation involves the resonant excitation of the second exciton state of the semiconducting nanotube.
		In addition to photoconductivity, photovoltage was observed when two nonequivalent Schottky barriers at the contacts break the mirror symmetry of the device.
	pubs.acs.org /cgi-bin/jcen?nalefd/3/i08/html/nl034313e.html (3696 words)

	Nano and Giga Abstract (Site not responding. Last check: 2007-10-08)
		Spectral dependence of the photoconductivity was studied at the range 0.6 - 2.0 mm.
		In particular, this photoconductivity shows great time of photocurrent's reaching stationary condition and its relaxation (~10-15 s.).
		Photoconductivity with great times of reaching of stationary condition was found in superthin films (d
	www.atomicscaledesign.net /moscow/abstracts/pudonin (217 words)

	Photoconductivity
		Photoconductivity refers to the difference of electrical conductivity of a device with and without illumination.
		Measurement of photoconductivity consists of I - V measurements conducted under dark (reference) and under illumination (having the intensity of light and its wavelength as parameters).
		Very important for safety of the Lamp is to turn off first the left side switch (Lamp) and wait until current(lamp filament) drops to zero then turn off general switch of lamp Power supply.
	www.fisk.edu /~aburger/Published03_06/Measurement_/Photoconductivity/photoconductivity.html (350 words)

	Nano and Giga Abstract
		The unusually high value of the photoconductivity effect in the nanogranular materials attracts the attention of a number of researchers.
		However, some specific features of photoconductivity in nanogranular materials is still a puzzling problem.
		The observed features of photoconductivity behavior are interpreted qualitatively accounting for the nanopores existing in the studied samples.
	www.atomicscaledesign.net /moscow/abstracts/ryzhikov1 (201 words)

	2004 Sixth Annual Symposium - Bond-Watts Abstract (Site not responding. Last check: 2007-10-08)
		In addition, the photoconductivity of the aggregates was analyzed.
		Four effects have been observed in conductivity experiments; a fast rise in photoconductivity followed by a slow phase, a slow decay of photoconductivity without light excitation, and a short circuit photocurrent.
		Photoconductivity of thin films of TPPS aggregates was also explored.
	www.beckman-foundation.com /04bsp/bwatts.html (205 words)

	Lifetime and Longevity of an Intense, Photoconductivity - Switched Stacked Blumlein Modulator for Ultra - Wideband HPM ...
		Issues concerning the switch longevity were studied by fabrication and testing the GaAs photoconductive switches treated with the amorphic diamond under different switch configuration, gap settings, and diamond coating thickness.
		A significant improvement in switch lifetime was demonstrated by coating the cathode and anode areas of a GaAs photoconductive switch with amorphic diamond and testing its performance in a high power operation with a prototype stacked Blumlein pulser.
		In addition, elementary processes involved in conduction of a diamond-treated photoconductive switch were extensively examined.In this work, experiments with the stacked Blumlein prototype pulsers were conducted under different conditions of operation at power levels bypassing 100 MW.
	www.stormingmedia.us /38/3886/A388614.html (472 words)

	Position sensor microsystem based on Hall devices
		The change in offset voltage is proportionnal to the change in conductivity of the two resistances in the bridge that are not covered with metal.
		Since free excess carriers are recombined very quickly after the light has been switched off, the persistent photoconductivity we are then measuring should be related to the deep electronic states with very low emission and capture timeconstants.
		The current used for driving the bridge was 500 µA. The average change in offset voltage is 140 µV for the CZ and 5 µV for the FZ.
	lmis3.epfl.ch /research/old/photocond (530 words)

	On Thermal Quenching of the Photoconductivity in Hydrogenated Amorphous Silicon (Site not responding. Last check: 2007-10-08)
		On Thermal Quenching of the Photoconductivity in Hydrogenated Amorphous Silicon
		Thermal quenching (TQ) of the photoconductivity sigma(p) is the decrease in sigma(p) with increasing temperature.
		With computer simulations employing the theory of Simmons and Taylor, we show that TQ is caused by the natural density of gap states of a-Si:H. The onset of thermal quenching occurs at the temperature T-TQ where the trapped hole density in the valence band tail has decreased to twice the density N-D of dangling bonds.
	mrsec.uchicago.edu /new_abstracts/fritzsche014.html (125 words)

	MIJ-NSR Vol. 5S1, Art. W11.45, A. J. Ptak et al. (Site not responding. Last check: 2007-10-08)
		Photoconductance decay and spectral photoconductance measurements were made on a set of ten undoped layers of GaN grown by rf-plasma MBE.
		Spectral photoconductance indicated transitions at 1.0-1.1, 1.92, 2.15, 3.08 and 3.2-3.4 eV.
		Analysis of photoconductance decay indicates that more than one type of persistent photoconductivity may be present.
	nsr.mij.mrs.org /5S1/W11.45 (195 words)

	Journal of Electronic Materials: DC photoconductivity study of semi-insulating Cs(1-X)Zn(X)Te crystals
		A direct current (DC) photoconductivity study of the detector grade CZT crystals is helpful to characterize and improve the transport properties of CZT.
		The main purpose of this paper is to correlate the detector performance with DC photocurrent measurements, and to distinguish surface effects from bulk effects.
		This model has been successfully employed to study the surface generation and recombination effects in the photoconductivity of HgI^sub 2^ single crystals.2 In this paper, we show that the recombination velocities of two surfaces can differ dramatically even though both surfaces are treated in the same etching solution.
	www.findarticles.com /p/articles/mi_qa3776/is_200106/ai_n8955672 (1119 words)

	IYTE-Thesis Subjects of Graduated Students / Gökhan ERDOĞAN
		In this study low temperature photoconductivity of undoped hydrogenated amorphous silicon(a-Si:H) thin films have been studied to investigate the effect of native and Staebler-Wronski defects.
		Fg) is close to unity and varies between 0.70 to 0.90, indicating recombination kinetics through the midgap defect states in the bandgap of a-Si:H. Low temperature photoconductivity versus 1000/T spectrum shows three distinctly different regions.
		The shape of low temperature photoconductivity spectra becomes almost the same for all samples even drastic differences were observed in the annealed state.
	www.iyte.edu.tr /tez/2001-2002/erdogan_ing.htm (485 words)

	Imaging On-Line Store (Site not responding. Last check: 2007-10-08)
		The effect of water desorption on the dark conductivity and photoconductivity at elevated temperatures has been investigated in evaporated thin films of the X-phase of MgPc.
		Both dark conductivity and photoconductivity are found to greatly diminish with the onset of water desorption around 150 ° C. This is due to the scattering of charge carriers at defects formed by collapse of the vacancies of water molecules.
		Especially, the photoconductivity is quite sensitive to subtle structural changes due to thermal motion of water molecules in the lattice, even before water desorption.
	www.imaging.org /store/epub.cfm?abstrid=22098 (304 words)

	2.1.3 Far-infrared photoconductivity of GaN MOCVD epilayers grown on sapphire (Site not responding. Last check: 2007-10-08)
		Therefore we suggest that the photoconductivity is due to changes of the mobility of the carriers responsible for the low temperature conductivity, caused by the FIR radiation.
		To model such behaviour the FIR response of the sample (layer and substrate) was calculated using the transfer matrix method on the basis of the Dynamic Dielectric function, taking into account GaN and sapphire phonons.
		The quantity E describes the photoconductive response of a conducting layer on an isolating substrate, due to the bolometric effect.
	www.magniel.com /hmtj/annual/213.html (407 words)

	Temperature dependence of dc photoconductivity in CdTe thin films (Site not responding. Last check: 2007-10-08)
		The temperature dependence of dc photoconductivity in the measuring range 303--417 K
		A decrease in photosensitivity with increase in temperature is attributed to the reduction of photoexcitation process.
		It is observed that the minority carrier lifetime varies inversely with light intensity which supports the sublinear relationship of photoconductivity with the intensity of light and thereby confirms the defect-controlled photoconductivity in CdTe thin films.
	www.ias.ac.in /pramana/v60/p1247/abs.htm (134 words)

	Journal of Electronic Materials: hall mobility and its relationship with persistent photoconductivity of undoped GaN, ... (Site not responding. Last check: 2007-10-08)
		The induced persistent photoconductivity (PPC) effect is therefore related to the Hall mobility through intrinsic electrically active defects.
		The properties of those defects were further investigated by monitoring a transient change of resistivity after removal of illumination at different temperatures.
		It reveals that the recapturing process of excited electrons into illumination-neutralized defects is the mechanism responsible for the PPC effect of undoped GaN.
	www.findarticles.com /p/articles/mi_qa3776/is_200001/ai_n8895018 (1140 words)

	Photoelectric phenomena and metastable states in amorphous semiconductors (Site not responding. Last check: 2007-10-08)
		Systematic studies of conductivity, photoconductivity and optical absorption in doped and undoped a-Si:H enable to understand the main recombination mechanisms of nonequilibrium carriers in a-Si:H and the influence of the temperature and doping on these processes, including thermal quenching of photoconductivity.
		Characteristics of the temperature dependence of the photoconductivity of a-Si:H, doped lightly with boron.
		Saturation of the photoconductivity and characteristics of annihilation of photostimulated defects in undoped a-Si:H. Sov.
	scon155.phys.msu.su /eng/amorph.html (326 words)

	Persistent photoconductivity and photoinduced superconductivity in oxides (Site not responding. Last check: 2007-10-08)
		Persistent photoconductivity (PPC) is a phenomenon where the conductivity of a material shows persistent increases when illuminated at a certain wavelength.
		By persistent we refer to a situation where the light induced conductivity does not decay when illumination ceases, as is normally the case in semiconductors.
		To study this physics we employ thin film growth by reactive sputtering, structural characterization techniques and a wide range of photoconductivity and magnetotransport measurements.
	physics.ucsd.edu /~iksgrp/PPC.html (277 words)

	Characteristics of photoconductivity in As-Sb-Se glasses (Site not responding. Last check: 2007-10-08)
		The temperature dependence of photoconductivity has been analysed in terms of the ABFH model and both systems are found to exhibit type I photoconductivity.
		The composition dependence of photoconductivity is explained on the basis of chemi-cally ordered covalent network (COCN) model.
		Photoconductivity response time of the two systems have been determined from frequency-resolved photocurrent (FRPC) measurements.
	www.ias.ac.in /pramana/nov1999/p5126.htm (132 words)

	Research Interests (Site not responding. Last check: 2007-10-08)
		This also allows to determine optical bandgap of a-Si:H. Since transmission and reflection measurements are not sensitive at lower energies, absorption coefficient due to defect states for lower energies can be obtained using sub-bandgap absorption techniques which directly give information about the densities of continuous midgap defect states lying in the bandgap.
		Because there are several advantages of DBP over other techniques, I have extensively used DBP technique together with steady-state photoconductivity and optical absorption in the visible region.
		From the self-consistent analysis of sub-bandgap absorption and steady-state photoconductivity results It has been found that three Gaussian distributions of charged defect states are the better representation of native and Staebler-Wronski defects in a-Si:H thin films.
	photon.iyte.edu.tr /~mgunes/Research.htm (1122 words)

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