Literature Review - INFLIBNET Centre · 2018. 9. 15. · In this paper, ZnO nanoparticles (NPs)...
Transcript of Literature Review - INFLIBNET Centre · 2018. 9. 15. · In this paper, ZnO nanoparticles (NPs)...
Literature Review:
Mishra, Srivastava, Prakash, Yadav, and Panday (2011),
In this paper, cadmium sulfide (CdS) quantum dots (QDs) are synthesized
by a simple co-precipitation method. X-ray diffraction (XRD) confirmed
the formation of a cubical zinc blend structure of CdS nanoparticles.
Transmission Electron Microscopy (TEM) images revealed that the CdS
QDs are of 2-5 nm in size. To study the photoconductivity, the field
dependence of the photocurrent and the dark-current was assessed, as was
the time-resolved rise and decay photocurrent spectrum and wavelength
dependence photocurrent spectrum assessment of the CdS QDs. The
wavelength-dependence of the photocurrent was found to be close to the
absorption and PL spectrum. These CdS QDs can find potential
application in optoelectronic devices and photodetectors.
Chen, Wang, Chien, Chang, Chuang (2011),
In this paper, proposes a new method for reducing power consumption
and enhancing the luminous efficiency of powder inorganic
electroluminescence devices by introducing a composite dielectric layer
into their structure. The composite dielectric layer contains a composite
BaTiO3-carbon nanotube (CNT) film, which is formed by adding single-
wall CNTs into a BaTiO3 layer. With an appropriate CNT mixing ratio,
the power consumption decreased by more than 30%, and the luminous
efficiency increased by approximately 50% at a brightness of 400 nits and
an operation frequency of 1 kHz.
Mishra, Srivastava, Srivastava, Panday, Prakash (2011),
In this paper, simple, low-cost, and direct route is used for the UV-
photodetection and photoluminescent zinc-oxide nanoparticles (NPs) by
decomposing zinc acetate in air at 400 0C for 12 hrs. The X-ray
diffraction (XRD) result indicates that the synthesized ZnO NPs is pure
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and single crystalline structure with wurtzite type. The synthesized ZnO
NPs exhibits several photoluminescence peaks centered at 396 nm, 418
nm, 441 nm, 481 nm and 522 nm. The variation of photo and dark-current
with applied field is found to follow power law i.e I α V. At low voltage
the behavior is sub-linear which becomes super-linear at high voltages.
Mishra, Srivastava, Prakash, Yadav, Panday (2011),
In this paper, Mn-doped CdS nanoparticles (NPs) have been synthesized
by co-precipitation method and effect of Mn concentration on the
structural, photoluminescence and photoconductivity properties have
been studied. The X-ray diffraction (XRD) patterns show that the
synthesized NPs have a cubical (zinc blende) phase. In photoconductivity
study, variation of photocurrent with voltage on ln-ln scale is found to
follow power law superlinearly due to injection of additional charge
carriers from one of the electrodes. The growth and decay in photocurrent
spectra exhibit anomalous behaviors which may be attributed to photo-
induced chemisorptions of oxygen molecules on surface of NPs.
Maurya, Chauhan, Mishra, Srivastava (2011),
In this paper, the influence of two different calcination temperatures 80 ◦C
and 450 ◦C on the structural, optical and charge transport properties of
rutile TiO2 nanocrystals has been investigated. TiO2 nanocrystals have
been prepared at low temperature by a simple hydrolysis method using
titanium tetrachloride as starting precursor. The results of X-ray
diffraction (XRD) showed that the prepared nanocrystals have a rutile
tetragonal crystalline structure. The red-shift in photoluminescence (PL)
is attributed to the change in strain from compressive to tensile.
Photoconductivity (PC) measurements showed that capture cross-section
of 80 ◦C (R1) and 450 ◦C (R2) calcinated rutile nanocrystals are
55.10×10−10
and 39.50×10−10
cm2 respectively.
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Kripal, Gupta, Srivastava, Mishra (2011),
In this paper, photoconductivity and photoluminescence studies of ZnO
nanoparticles (NPs) synthesized by coprecipitation method capped with
thioglycerol are carried out. The effect of annealing at 300 0C is also
studied. The transmission electron micrograph (TEM) and X-ray
diffraction (XRD) pattern confirm the hexagonal wurtzite structure of
ZnO nanoparticles. The photoluminescence (PL) spectra of assynthesized
ZnO NPs show band edge emission as well as blue–green emission. After
annealing band edge emission is quenched. Photocurrent is found to vary
super linearly at high voltage for both as-synthesized as well as annealed
ZnO NPs. Time resolved rise and decay photocurrent spectra are found to
exhibit anomalous photoconductivity for as-synthesized as well as
annealed ZnO NPs wherein the photocurrent decreases even during
steady illumination.
Nalla, Polavarapu, Manga, Goh, Loh, Xu and Ji (2010),
In this paper, a water soluble conjugated thiophene polymer, sodium salt
of poly[2-(3-thienyl)ethoxy-4-butylsulfonate] (TPP), and graphene oxide
(GO) composite film (GO–TPP) device was prepared. Transient
photoconductivity measurements were carried out on the GO–TPP
composite film using 150 ns laser pulses of 527 nm wavelength. The
relationships of the film photoconductivity, photocurrent decay time and
electron decay times with the incident light intensity were investigated.
The photoconductive gain of the film was determined to be greater than
40% and to be independent of the light intensity.
Chen, Chen, Lien, Ding, and He (2010),
In this paper, the Au nanoparticle (NP) decoration as an effective way to
enhance both photocurrent and photoconductive gain of single ZnO
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nanowire (NW) photodetectors (PDs) through localized Schottky effects.
The enhancement is caused by the enhanced space charge effect due to
the existence of the localized Schottky junctions under open circuit
conditions at the NW surfaces, leading to a more pronounced electron-
hole separation effect. Since the band-bending under illumination varies
relatively small for an Au NP-decorated ZnO NW, the decay of gain is
less prominent with increased excitation power, demonstrating the
feasibility for a PD to maintain a high gain under high-power
illumination.
Singh, Mishra, Srivastava and Gopal (2010),
In this paper, semiconductor quantum dots (QDs) and their assemblies
have shown potential research interest due to their size dependent optical
and electronic properties. Most of the available reports in this field are
related to the laser induced modification of shape, size, and morphology
of noble metal nanoparticles, while only few exist for semiconductors.
UV-visible absorption, XRD, TEM, and PL spectroscopic methods are
utilized for the characterization of as synthesized QDs and raw NPs. Size
and hence optical properties of produced selenium QDs are found to be
highly dependent on the time of irradiation. The size of the produced
selenium QDs follows a second order exponential decay function of
irradiation time, while the rate of size reduction, da/dt, is directly
dependent on the diameter, a, of the instantaneous QDs, very similar to
the radioactive decay model.
Antic, Krsmanovic, Marinovic-Cincovic and Dramicanin (2010),
In this paper, there is an increasing interest in obtaining and investigating
composite materials that comprise nanoparticles as fillers and polymers
as matrix. Such composites may display combined features of both
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components, and sometimes even novel properties resulting from their
mutual interactions. It is important that both unique size-dependent
properties of nanoparticles and favorable properties of polymer material
remain preserved in the composite. Influence of Gd2O3:Eu3+
filler on the
modification of glass transition and thermo-degradable properties of the
polymer matrix is also investigated. Thermal analyses give evidence of
unchanged thermal stability of polymer phase in the composites.
Zou and Gao (2010),
In this paper, we have reported our most recent work on processing and
microstructure of nano-structured oxides and their photoluminescence
and photo-catalysis properties. Zinc oxide and related transition metal
oxides such as vanadium pentoxide and titanium dioxide were produced
by a combination of magnetron sputtering, hydrothermal growth and
atmosphere controlled heat treatment. These structures showed special
properties such as much enhanced photoluminescence and chemical
reactivity. The photo-catalytic properties have also been promoted
significantly. The transition metal oxides with different band gaps have
much enhanced photoluminescence under laser stimulation. The mixed
oxide complex may provide a promising way to high-efficiency photo
emitting materials and photo-catalysts.
MISHRA, SRIVASTAVA, PRAKASH, YADAV, and PANDAY
(2010),
In this paper, ZnO nanoparticles (NPs) with particle size of 20–50 nm
have been synthesized by hydrothermal method. Photoluminescence (PL)
and photoconductive device characteristics, including field response, light
intensity response, rise and decay time response, and spectral response
have been studied systematically. In spectral response curve of ZnO NPs,
the wavelength dependence of the photocurrent is very close to the
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absorption and photoluminescence spectra. The photo generated current,
Ipc = (Itotal – Idark) and dark current Idc varies according to the power law
with the applied field Ipc α Vr and with the intensity of illumination Ipc α
ILr, due to the defect related mechanism including both recombination
centers and traps. The photo and dark conductivities of ZnO NPs have
been measured using thick film of powder without any binder.
SRIVASTAVA, MISHRA, YADAV, SRIVASTAVA, PANDAY,
PRAKASH (2010),
In this paper, an attempt has been made to study the photoconductivity
and dark-conductivity characteristics of doped ZnS nanoparticles.
Photoconductivity and dark-conductivity are measured at room
temperature under visible illumination. The Mn-doped ZnS nanoparticles
synthesized by co-precipitation technique are found to exhibit anomalous
behavior of photocurrent which decreases with increased intensity of
illumination. At 5000 lux of illumination photocurrent is found to be even
lower than the dark-current. The variation of photocurrent with applied
voltage is super-linear. Structural studies using XRD and TEM have been
performed.
Kripal, Gupta, Mishra, Srivastava, Pandey, Prakash (2010),
In this paper, Mn2+
doped ZnS nanoparticles are characterized using UV–
vis, photoluminescence and photoconductivity studies. The size of Mn2+
doped ZnS NPs is estimated to be 2–4nm by X-ray diffraction. UV–vis
spectra show a blue shift in absorption edge as compared to bulk
counterpart. Photoluminescence spectra indicate that orange
luminescence varies with Mn2+
concentration. The Mn2+
doped ZnS
nanoparticles are found to be photosensitive. The doping of Mn2+
ions
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improves the photosensitivity of the ZnS nanoparticles system. The time-
resolved rise and decay of photocurrent indicate anomalous behavior
during steady state illumination.
MISHRA, MISHRA, PRAKASH (2009),
In this paper, transparent conducting tin oxide (SnO2) thin film has been
deposited on glass substrate by spray pyrolysis technique, taking starting
material tin chloride solution (SnCl2.2H2O) and using ultrasonic nebulizer
at substrate temperature 300±10 oC. The XRD result shows a regular,
smooth morphology. The deposited film was found to be polycrystalline..
The optical absorption, transmittance, reflectance and optical
conductivity have been measured. It was found that the average
transmittance of the film is around 78 % at wavelength 550 nm. Finally
the ethanol gas sensing properties of the film was also performed.
Wang, Ye, Zhang, Li, G. H. (2009),
In this paper, ZnTiO3 thin films were prepared by radio frequency
cosputtering of ZnO and TiO2. It was found the as-prepared film is
amorphous and the cubic phase ZnTiO3 films form after annealing at
temperature above 500°C. The absorption spectra indicate that the optical
band gap of the crystalline ZnTiO3 film is about 3.70 eV. A strong
photoluminescence band centered at 355 nm consisting of two emission
peaks was observed in 800°C annealed ZnTiO3 thin film, and the peak
positions of these two emission move to short wavelength with increasing
annealing temperature.
Mishra, Srivastava, Prakash (2009),
In this paper, we report on the photoconductivity (PC), dark-conductivity
and photoluminescence (PL) measurements of hydrothermally
synthesized Zinc oxide (ZnO) nanoparticles (NPs) with particle size 20-
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50 nm. The photoconductivity is observed in ZnO nanoparticles due to
photoexcitation in the visible range (400 nm- 691 nm). The photo and
dark current behavior as a function of various parameters such as field
response, rise and decay time response was studied. The photocurrent
(Ipc) and dark-current (Idc) follows power law with applied field, Ipc α V r
due to the defect related mechanism including both recombination centers
and traps.
Aizawa, Ohtani (2009),
In this paper, we fabricated and characterized electroluminescence (EL)
devices using ferroelectric polyvinylidene fluoride/trifluoroethylene
(PVDF/TrFE) copolymer composites mixed with Mn- and Cu-activated
ZnS phosphor particles. Increases of the luminescence were observed in
the fabricated EL devices using PVDF/TrFE copolymer in comparison
with using PVDF polymer as dielectrics. EL emission intensities were
also enhanced by applying the bipolar pulses. These results suggest an
effect of polarization reversal in the composite films.
Cheng, Lu, Shambat, Yu, Saraswat, Vuckovic, and Nishi (2009),
In this paper, we report the room temperature electroluminescence (EL)
at 1.6 μm of a Ge n+/p light emitting diode on a Si substrate. Unlike
normal electrically pumped devices, this device shows a superlinear
luminescence enhancement at high current. By comparing different n type
doping concentrations, we observe that a higher concentration is required
to achieve better efficiency of the device. Thermal enhancement effects
observed in temperature dependent EL spectra show the capability of this
device to operate at room temperature or above. These detailed studies
show that Ge can be a good candidate for a Si compatible light emitting
device.
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Chassaing, Demangeot, Paillard, Zwick, Combe, Pagès, Kahn,
Maisonnat and Chaudret (2007),
In this paper, surface optical phonons in freestanding cylindrical ZnO
nanoparticles surrounded by organic molecules have been theoretically
investigated using a dielectric continuum model and experimentally with
Raman spectrometry. We also investigate the dispersion of these modes
regarding the dielectric constant of the outer medium. By modelling the
organic shell of nanoparticles with a dielectric constant and based on
experimental results of Raman spectrometry, we show that we observed a
top surface mode of nanoparticles.
O’Brien, Kherani, Zukotynski, Ozin, Vekris, Tetreault, Chutinan,
John, Mihi, and Míguez (2007),
In this paper, photonic crystals (PCs) are a remarkable class of materials
wherein the periodicity of the index of refraction can be engineered to
obtain unprecedented optical properties that have no parallels in other
materials. Some interesting optical phenomena inherent to PCs include
second harmonic generation, the super-prism effect, photonic bandgaps
(PBGs) and “slow photons”. The ability of defect modes in PCs to
confine photons is expected to provide the infrastructure for optical
circuits. Moreover, lossless light propagation along PBG waveguides
with coupling to quantum dots or optical cavities could provide new
avenues for quantum information processing.
VOMVAS1, POMONI, TRAPALIS, TODOROVA (2007),
In this paper, thin TiO2 sol-gel films, with and without ammonia
treatment, were prepared using the dip-coating technique and then heat
treated at 500 ºC. The time dependences of the photoconductivity at
various light intensities were studied in vacuum and in air at 27 ºC. The
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transient photoconductivity is very sensitive to the environment and
dramatically higher than the dark one for samples both in vacuum and in
air. The results are discussed in terms of the competition of the
photogeneration, recombination, thermal release, and the influence of
NH3 treatment.
LI, CHEN, SHEN, JIANG, ZHANG (2007),
In this paper, α-Si3N4 was prepared using MgO and Al2O3 as the sintering
additives and spark plasma sintering (SPS) technique. The SPS sintering
behavior and mechanism have been discussed. The relationship between
the content of sintering additives, sintering temperature, and relative
densities of the samples has been analyzed. The phase composition was
determined by XRD, the microstructures of the fracture surfaces were
observed by SEM and the dielectric properties have been tested. The
dielectric loss, influenced by the liquid phase, is less than 1×10–2
.
WODECKA-DUŚ, LISIŃSKA-CZEKAJ, ORKISZ, ADAMCZYK,
OSIŃSKA, KOZIELSKI, CZEKAJ (2007),
In this paper, the sol-gel derived powders of the chemical composition
(Ba0.6Sr0.4)TiO3 (BST) were used in the preparation of ceramic samples.
Barium acetate, strontium acetate and tetra-butyl titanate were used as
starting materials. The free sintering method was used for the final
densification of ceramics. The ceramic samples were characterized in
terms of their crystalline structure (X-ray diffraction), microstructure
(scanning electron microscopy), chemical composition (energy dispersive
spectroscopy), and dielectric properties.
Tang, Teng, hao, Liang, Wang (2007),
In this paper, photoconductivity is considered to be an important tool for
providing information regarding the nature of the photo-excitations. Since
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last decade the photoconductive properties of the inorganic nanoparticles
have become subject of intensive study.
He, Lin, McConney, Tsukruk, and Wang (2007),
In this paper, UV photodetector fabricated using a single ZnO nanobelt
NB has shown a photo response enhancement up to 750 times higher than
that of a bare ZnO NB after coating with -20 nm plasma polymerized
acrylonitrile PP-AN nanoscale film. The mechanism for this colossal
photoconductivity is suggested as a consequence of the efficient exciton
dissociation under UV illumination due to enhanced electron transfer
from valence band of ZnO NB to the PP-AN and then back to the
conduction band of ZnO. This process has demonstrated an easy and
effective method for improving the performance of the nanowire/NB-
based devices, possibly leading to supersensitive UV detector for
applications in imaging, photosensing, and intrachip optical
interconnects.
Hu, Zhang, and Gao (2006),
In this paper, solid-state electroluminescent devices based on organic
polymers have been extensively studied in recent years for potential
display and lighting applications. Electroluminescence (EL) is the
generation of light by electrical excitation. For a material to exhibit EL, a
general criterion is that it must also possess photoluminescence (PL),
which is an intrinsically more efficient process, as electrons and holes are
always created in pairs and in close proximity, making radiative
recombination a favorable process. A material that is not
photoluminescent or whose PL is heavily quenched is therefore very
unlikely to be a good candidate for EL. Although most “conventional”
polymer light-emitting diodes (PLEDs) are metal–insulator–metal (MIM)
structures based on pristine luminescent polymers, EL from polymers can
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be achieved alternatively by the formation of a light-emitting p–n
junction via in situ electrochemical doping.
ANDRI, ANIN, JOKANOVI, ANIN, MITRI, VIANA (2006),
In this paper, the luminescent properties of a composite made from
isotactic polypropylene and silicate nano powder doped with trivalent
europium ion were investigated. The method for obtaining the
investigated composite is presented. Thermo-chemical properties of the
composite were determined by DSC and TG measurements, while the
structure was checked by X-ray diffraction measurements. Luminescent
properties for two differently crystallized nano-composites were
determined by measuring room temperature excitation and emission
spectra, as well as the emission lifetime of the 5D0-7F2 transition. In
addition, much stronger luminescence intensity was noticed for the case
of polypropylene of higher crystallinity.
Murphy, Moazzami and Phillips (2006),
In this paper, a strong photoconductive response is observed for ZnO
epilayers in the presence of both above bandgap and below bandgap
photoexcitation. Photoexcitation for energies larger than the band gap,
results in a photoconductive response with fast and slow time constants
on the order of nanoseconds and larger than milliseconds respectively. A
model for the photoconductive response based on rate equations is
presented providing an accurate fit to measured photoconductivity data.
The passivation of the ZnO surface with SiO2 shows significantly reduced
photoconductive transient decay time constants, suggesting a significant
reduction of deep surface defects on the ZnO material.
Hui and Onga, Lee and Dai (2005),
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In this paper, the effects of AlOx-cap layer on the optical and
photoelectrical properties of ZnO films have been studied by
cathodoluminescence (CL), photoluminescence (PL), and
photoconductivity (PC). Both the PL and CL show that the cap layer
improves the emission characteristics of ZnO by enhancing the band-edge
emission while at the same time reducing the deep-level emissions. To
study the origin of improvement, depth-resolved CL has been carried out
to map out the emissions at different depths. The PC measurement on the
capped ZnO at room temperature shows a distinctive excitonic feature at
3.29 eV and an overall increment of photo-response above the band gap.
SINGH, GANDOTRA, SINGH and CHAKRAVARTY (2005),
In this paper, minority carrier lifeline, t, is one of the most important
parameters which has a decisive effect on the performance of silicon
devices based on excess carriers. The value of t is greatly affected by the
presence of impurities and defects in silicon and its value provides a fair
indication of quality of the material. Photoconductivity decay (PCD) and
photocurrent generation (PCG) methods are simple and low cost methods
of measurement of minority carrier lifetime in silicon wafers. However,
their application requires care. For PCG method the t measurement under
vacuum conditions provides correct and consistent results.
BENOUIS, JUAREZ, AIDA, HAMZAOUI, BENHALILIBA (2005),
In this paper, the photoconductivity of ZnO thin films prepared by spray
pyrolysis of the zinc dehydrated was studied. The electrical, optical
behaviors and structural spectra show an important effect of substrate
temperature Ts and deposition time td. Under illumination, the
conductivity of as grown sample increased due to desorption of oxygen.
A small photoconductivity is representative of the electrical behavior of a
quasi intrinsic material. By following cessation of illumination, we
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remarked a saturation of decay photoconductivity; this can be attributed
to a trap which captures carriers.
Scheblykin, Lepnev, Vitukhnovsky, Auweraer (2001),
In this paper, a composite material of poly(phenylenevinylene) (PPV)
doped by dye aggregates was prepared. A very efficient and temperature
activated energy transfer (ET) from the PPV to the dye aggregates was
attributed to F. orster ET accompanied by exciton diffusion. A clear
complementary relation between the photoluminescence (PL) and
electroluminescence (EL) images was observed for thin (15 nm) PPV-
based OLEDs. So-called „„black spots‟‟ in EL become bright ones when
the photoluminescence of the same area was excited. This effect was
attributed to the presence of an insulating layer between the polymer and
aluminum.
Cordero, Carson, Estabrook, Strouse, and Buratto (2000),
In this paper, we show that the luminescence from CdSe quantum dot
monolayers can be strongly influenced by the interaction of water
molecules adsorbed on the surface. Light induced alterations in the
surface states following adsorption of water, results in quasi-reversible
luminescence changes in the quantum dot. The exciton emission exhibits
an exponential blue shift of nearly 16 nm (60 meV) over 1 h of
illumination. Our model suggests that water molecules adsorbed on the
surface of the quantum dot act to passivate surface traps, which results in
increased luminescence, similar to an effect well-known for bulk CdSe
surfaces.
Tajkhorshid, Suhai (1999),
In this paper, we performed DFT calculations, using the DMOL
implementation of the COSMO solvent model, to investigate the effect of
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different dielectric responses of the environment on the structure and
electronic configuration of two un-substituted Schiff base models of
retinal, including three and four conjugated double bonds, as well as a
monomethylated model. The results show that the application of different
dielectric constants in the calculations significantly influences the proton
affinity of the molecule.
Studenikin, Golego, and Cocivera (1998),
In this paper, photoluminescent, undoped ZnO films have been fabricated
using spray pyrolysis of zinc nitrate solution. The luminescent films had a
polycrystalline hexagonal wurtzite type structure with no preferred
orientation. Photoluminescence intensity was critically dependent on
substrate temperature during spray pyrolysis and on post-annealing
temperature. Green, photoluminescent films possessed a porous structure
while orange films possessed a close packed granular morphology. Green
luminescence appears to be due to oxygen vacancies in a layer just below
the crystallite surface.
Studenikin, Golego, and Cocivera (1998),
In this paper, slow relaxation of the photoconductivity over a period of
days was studied in polycrystalline ZnO and TiO2 films prepared by
spray pyrolysis. The phenomenon is described by a model involving deep
sensitizing hole traps in the forbidden gap. The trap state distribution
based on this model was calculated using an improved Laplace transform
method. For ZnO and TiO2 films, the density of states was shown to have
a peak-like distribution with a maximum near the lower third of the
energy gap.
Shen and Perera (1998),
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In this paper, the photoconductivity generation mechanism and
photoconductive gain in internal photoemission infrared detectors have
been studied. A simple model is proposed and it shows that the
photoconductive gain of internal photoemission detectors is less than but
close to unity and independent of the number of the emitter layers, while
the current responsivity is proportional to the number of emitter layers.
The results, in good agreement with the experiments, are contrary to
those of quantum-well photodetectors due to the different photocarrier
generation mechanisms between the quantum-well photodetectors and
internal photoemission detectors.
Bernatskii (1994),
In this paper, the photoluminescence (PL) spectrum of thin films of
cadmium fluoride (CdF2), activated by manganese chloride (MnC12),
consists of a band with )~ max = 520 nm, characteristic of the Mn 2 +
ion in this compound, and bands with maxima 685 and 780 nm, which
depend on the energy of the exciting radiation . In the x-ray and cathode
luminescence spectra, bands with maxima 375, 530 and 530 nm,
respectively, are observed, and in the electroluminescence spectrum a
band with hma x = 530 nm.
Devi and Prakash (1994),
In this paper, we deals with the photoconductivity studies of (PbCrO4-
HgO-ZnO) composites comprising of base materials of three different
energy gaps. The response of (10%PbCrO4-80%HgO-10%ZnO) and
(20%PbCrO4-60%HgO-20%ZnO) composites is faster than that of other
compositions and of base materials. The dark current for (20%PbCrO4-
60%HgO-20%ZnO) is trap limited-space charge limited at higher
voltages while it shows non-ohmic behavior at lower voltages. The
photocurrent for (20%PbCrO4-60%HgO-20%ZnO) composition shows
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non-ohmic behavior at lower voltages and tends to saturation at higher
voltages. The photocurrent for the above composition varies sublinearly
with the intensity of illumination.
Lee, Yu, Moses, and Heeger (1994),
In this paper, we report the results of transient-photoconductivity
measurements on films of poly (phenylenevinylene) (PPV) in the sub-
nanosecond-time regime. The initial fast transient photocurrent decays
exponentially with a decay time of about 100 ps, followed by a slower
component with a decay time of about 600 ps. The magnitude of the fast
component is proportional to the light intensity and independent of
temperature, while the magnitude of the slower component is
proportional to the square root of the light intensity and decreases as
temperature decreases with thermal-activation energy of about 100 meV.
We attribute the initial response to photo-generated electrons and holes
{polarons) and the following slower decay to bipolarons in the non-
degenerate ground-state conducting polymer.
Watanabe, Haga, Tosomiya (1992),
In this paper, it has been shown that the photoconductive characteristics
of a dispersion composite of a photoconductive inorganic metal oxide,
such as TiO2, with a polymer are significantly enhanced by annealing.
For the poly (methyl methacrylate) (PMMA) dispersion composite TiO2-
PMMA, the relative sensitivity is 101 ∼ 10
2 times higher than that of the
unannealed sample. The space-charge limited current is observed in the
dark current-voltage characteristics of the annealed TiO2-PMMA. From
the light intensity index of the annealed TiO2-PMMA, it is found that the
annealed sample has a large sensitizing effect.
Objective of the present work:
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1. Study the dielectric material and its applications
2. Study of material with X-ray Diffraction (XRD)
3. Techniques or methods used for the fabrication of cell
4. Study the properties of photoconductivity in different ratio of the
material
5. Study the Photoelectret property of the material
6. Study the property of electroluminescence in different ratio of the
composite