• Journal of the Korean Institute of Telematics and Electronics D
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• v.35D no.2
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• pp.40-51
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• 1998

Electron transport properties are investigated by Monte Carlo simulation in n-HgCdTe. The material is easily degenerated at low temperature or being slightly doped, and is characterized by small band gap and large nonparabolic factor. The degeneracy is incorporated in the Monte Carlo simulation by taking into account the electron-electron scattering and the pauli exclusion principle. In the conventional method, however, the electron-electron scattering rate was developed under the assumption of parabolic conduction band. A new formulation of the electron-electron scattering rate is develop considering the band nonparabolicity and overlap integral. The electron-electron scattering effects on the electron distribution,impact ionization coefficienty, electron temperature, drift velocity and electron energy are presented.

• Transactions on Electrical and Electronic Materials
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• v.17 no.1
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• pp.37-40
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• 2016

Performance enhancement of organic light-emitting diodes (OLEDs) is investigated in a device structure of ITO/TPD/Alq₃/LiF/Al and ITO/TPD/Alq₃/BCP/LiF/Al. Here, bathocuproine (BCP) is used as an electron-transport layer. Current density-voltage-luminance characteristics of the OLEDs show that the performance of the device is better with BCP layer than without BCP layer. The current density, luminance, luminous efficiency, and external-quantum efficiency are improved by approximately 22%, 50%, 2%, and 18%, respectively. Since the BCP layer lowers the electron energy barrier, electron transport is facilitated and the movement of hole is blocked as the applied voltage increases. This results in an increased recombination rate of holes and electrons.

• Journal of Photoscience
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• v.10 no.2
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• pp.199-202
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• 2003

The relationship between the morphology of nanostructured TiO$_2$ films and the photo-injected electron transport has been investigated using intensity-modulated photocurrent spectroscopy (IMPS). For this purpose, three different TiO$_2$ films with 5 ${\mu}{\textrm}{m}$ thickness are prepared: The rutile TiO$_2$ film with 500 nm-sized cluster-like spherical bundles composed of the individual needles (Tl), the rutile TiO$_2$ film made up of non-oriented, homogeneously distributed rod-shaped particles having a dimension of approximately 20${\times}$80 nm (T2), and the anatase TiO$_2$ film with 20 nm-sized spherically shaped particles (T3). Cross sectional scanning electron micrographs show that all of the TiO$_2$films have a quite different particle packing density: poorly packed Tl film, loosely packed T2 film and densely packed T3 film. The electron transport is found to be significantly influenced by film morphology. The effective electron diffusion coefficient D$_{eff}$ derived from the IMPS time constant is an order of magnitude lower for T2 than for T3, but the D$_{eff}$ for the Tl sample is much lower than T2. These differences in the rate of electron transport are ascribed to differences in the extent of interparticle connectivity associated with the particle packing density.ity.

• Journal of the Korean Institute of Electrical and Electronic Material Engineers
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• v.22 no.4
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• pp.327-332
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• 2009

In the devices structure of ITO/N,N'-diphenyl-N,N' bis (3-methylphenyl)-1,1'-biphenyl-4,4'-diamine (TPD) /tris (8-hydroxyquinoline)aluminum$(Alq_3)$electron-transport-layer(ETL)(2,9-Dimethyl-4,7-diphenyl-1,10-phenanthroline(BCP))/Al, we have studied the efficiency improvement of organic light-emitting diodes depending on the thickness variation of BCP using electron transport layer. The thickness of TPD and $Alq_3$ was manufactured 40 nm, 60 nm under a base pressure of $5{\times}10^{-6}$ Torr using at thermal evaporation, respectively. The TPD and $Alq_3$ layer were evaporated to be deposition rate of $2.5{\AA}/s$. And the BCP was evaporated to be a4 a deposition of $1.0{\AA}/s$. As the experimental results, we found that the luminous efficiency and the external quantum efficiency of the device is superior to others when thickness of BCP is 5 nm. Also, operating voltage is lowest. Compared to the ones from the devices without BCP layer, the luminous efficiency and the external quantum efficiency were improved by a factor of four hundred ninty and five hundred, respectively. And operating voltage is reduced to about 2 V.

• Journal of Plant Biology
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• v.35 no.3
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• pp.247-252
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• 1992

The effect of iso-butanol on the electron transport rate of PS I and PS II was investigated in isolated spinach chloroplasts. In photosystem I, the rate of electron transport increased in the presence of 1 to 4% of isobutanol but decreased in 5 to 9% of iso-butanol. But in photosystem II, the rate of electron transport decreased when treated with 0.2 to 1% of iso-butanol. The inhibitory effect of isomers of butanol on PS II electron transport rate increased in the order of 2-butanol, tert-butanol, iso-butanol and I-butanol. This means that PS II activity was affected according to the arrangement of carbon atoms in butanol. The inhibitory effect of iso-butanol reduced when DPC was added in the solution. This means that iso-butanol affects PS II reduction side of thylakoid membrane primarily. The inhibitory effect of iso-butanol was reduced when $Mn^{2+},\;C^{2+}$ or BSA were added in the solution. PS II activity was restored when 1% iso-butanol treated chloroplast solution was diluted to twentyfold or when $Mn^{2+},\;C^{2+}$ or BSA was added to the diluted solution. However, the SDS-PAGE banding pattern of thylakoid membrane proteins was similar even in 2% iso-butanol treated chloroplasts and the control ones. Only in 5% iso-butanol treated chloroplasts these bands were very weak. These observations suggest that low concentrations of iso-butanol releases manganese and calcium ions from chloroplasts and inhibits the electron transport system. This inhibitory effect can be reversible in low concenterations but in high concentrations the inhibitory effect of iso-butanol become irreversible.rsible.

• Electrical & Electronic Materials
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• v.10 no.3
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• pp.268-273
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• 1997

In this paper the transient electron transport in GaAs bulk is simulated by using ensemble Monte Carlo method. To analyze the transient electron transport the 10000 electrons in the .GAMMA. valley are simulated simultaneously for 10 picoseconds. The electric field-velocity relation is obtained. The high impurity density reduces the negative differential resistance effect. The result of transient average velocity shows the electron velocity in the transient state is faster than that in the steady state. This transient velocity overshoot is caused by the intervalley scattering mechanism. And we confirmed the fact that the energy relaxation time is longer than the momentum relaxation time.

• Journal of Environmental Science International
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• v.1 no.1
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• pp.1.1-11
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• 1992

To find heavy metal-specific effects on the photosynthetic apparatus of higher plants, we investigated effects of $CuCl_2$, HgCl_2$ and $ZnCl_2$ on electron transport activity and chlorophyll fluorescence induction kinetics of chloroplasts isolated from barley seedlings. Effects on some related processes such as germination, growth and photosynthetic pigments of the test plants were also studied. Germination and growth rate were inhibited in a concentration-dependent manner by these metals. Mercury was shown to be the most potent inhibitor of germination, growth and biosynthesis of photosynthetic pigments of barley plants. In the inhibition of electron transport activity, quantum yield of PS II, and chlorophyll fluorescence induction kinetics of chloroplasts isolated from barley seedlings, mercury chloride showed more pronounced effects than other two metals. Contrary to the effects of other two metals, mercury chloride increased variable fluorescence significantly and abolished qE in the fluorescence induction kinetics from broken chloroplasts of barley seedlings. This increase in variable fluorescence is due to the inhibition of the electron transport chain after PS ll and the following dark reactions. The inhibition of qE could be attributed to the interruption of pH formation and do-epoxidation of violaxathin to zeaxanthin in thylakoids by mercury. This unique effect of mercury on chlorophyll fluorescence induction pattern could be used as a good indicator for testing the presence and/or the concentration of mercury in the samples contaminated with heavy metals.

• Applied Microscopy
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• v.17 no.2
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• pp.55-71
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• 1987

To investigate the effects of lead on the electron transport system and ultrastructure of mouse kidney mitochondria, various lead acetate concentrations were treated in vitro and respiration rate, enzyme activities were measured. Ultrastructural changes at state IV respiration were also observed. To compare with in vivo experiments, mouse were injected intraperitoneally of 100 mg lead acetate per kg body weight and state IV respiration rate and enzyme activities were measured. Ultrastructure of renal proximal tubular cells were also observed. In in vitro treatement, decreased state IV respiration, decreased enzyme activities, ruptured membranes and inhibition of condensed to orthodox transformation were observed. In in vivo treatment, decreased state IV respiration and decreased enzyme activities were observed after 24 hrs of i.p. injection. Cytochrome c oxidase activity showed twice the inhibition compared to NADH-CoQ reductase activity at 24 hrs. Continuous decreased state IV respiration was observed after 48 and 72 hrs of injection, however, the enzyme activities were increased to control level. Lead-protein complex which probably inhibits the toxic effects of lead appeared. To conclude, dominant effect of lead on the electron transport system appeared at cytochrome c oxidase activity, and the increased enzyme activities may be a result of appearance of lead-protein complex.

• Proceedings of the Korean Vacuum Society Conference
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• 2011.02a
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• pp.27-27
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• 2011

For the design of real applicable molecular devices, current-voltage properties through molecular nanostructures such as metal-molecule-metal junctions (molecular junctions) have been studied extensively. In thiolate monolayers on the gold electrode, the chemical bonding of sulfur to gold and the van der Waals interactions between the alkyl chains of neighboring molecules are important factors in the formation of well-defined monolayers and in the control of the electron transport rate. Charge transport through the molecular junctions depends significantly on the energy levels of molecules relative to the Fermi levels of the contacts and the electronic structure of the molecule. It is important to understand the interfacial electron transport in accordance with the increased film thickness of alkyl chains that are known as an insulating layer, but are required for molecular device fabrication. Thiol-tethered RuII terpyridine complexes were synthesized for a voltage-driven molecular switch and used to understand the switch-on mechanism of the molecular switches of single metal complexes in the solid-state molecular junction in a vacuum. Electrochemical voltammetry and current-voltage (I-V) characteristics are measured to elucidate electron transport processes in the bistable conducting states of single molecular junctions of a molecular switch, Ru(II) terpyridine complexes. (1) On the basis of the Ru-centered electrochemical reaction data, the electron transport rate increases in the mixed self-assembled monolayer (SAM) of Ru(II) terpyridine complexes, indicating strong electronic coupling between the redox center and the substrate, along the molecules. (2) In a low-conducting state before switch-on, I-V characteristics are fitted to a direct tunneling model, and the estimated tunneling decay constant across the Ru(II) terpyridine complex is found to be smaller than that of alkanethiol. (3) The threshold voltages for the switch-on from low- to high-conducting states are identical, corresponding to the electron affinity of the molecules. (4) A high-conducting state after switch-on remains in the reverse voltage sweep, and a linear relationship of the current to the voltage is obtained. These results reveal electron transport paths via the redox centers of the Ru(II) terpyridine complexes, a molecular switch.

• Proceedings of the Korean Institute of Electrical and Electronic Material Engineers Conference
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• 2003.07b
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• pp.1102-1105
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• 2003

Energy distribution function for electrons in $SF_6$-Ar mixtures gas used by MCS-BEq algorithm has been analysed over the E/N range $30{\sim}300[Td]$ by a two term Boltzmann equation and by a Monte Carlo Simulation using a set of electron cross sections determined by other authors, experimentally the electron swarm parameters for 0.2(%) and 0.5(%) $SF_6$-Ar mixtures were measured by time-of-flight(TOF) method, The results show that the deduced electron drift velocities, Electrons Drift Velocities for a rang of E/N values. As a consequence, it was known that the spatial growth rates and the dielectric behaviors in $SF_6$-Ar mixtures are strongly dependent on the addition rate of $SF_6$ gas but the transport coefficients of electrons are insensitive to the addition rate of $SF_6$ gas. The results obtained from Boltzmann equation method and Monte Carlo simulation have been compared with present and previously obtained data and respective set of electron collision cross sections of the molecules.