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Journal articles on the topic 'Charge carriers'

Author: Grafiati
Published: 4 June 2021
Last updated: 1 February 2025

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1

Hermosilla Palacios, Martha Alejandra, Marissa Martinez, Jeff Blackburn, and Alexander Spokoyny. "Quantifying Free Carriers in Doped SWCNTs: An Optical and Magnetic Resonance Approach." ECS Meeting Abstracts MA2023-01, no. 10 (August 28, 2023): 1188. http://dx.doi.org/10.1149/ma2023-01101188mtgabs.

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Single-walled carbon nanotubes (SWCNTs) have become increasingly important for opto-electronic devices due to their strong optical absorption, tunable carrier densities, and large carrier mobilities. To produce electricity in applications like photovoltaics and sensors, after light absorption the bound exciton must be separated into free charges carriers. However, the nature of charges in s-SWCNTs is still unclear and a way to quantify them has remained elusive. To better understand free carriers in doped semiconducting SWCNTs we employ a new class of molecular charge-transfer dopants, functionalized dodecaborane (DDB) molecules, to tune the charge carrier density. These DDB dopants form delocalized hole charge carriers on the SWCNTs due to the spatial separation between nanotube surface and the boron cluster containing the negative counterion. Importantly, the fluorine-decorated DDB dopants have strong 19F resonances, characteristic of the negatively charged molecules, that can quantify the absolute concentrations of DDB- and SWCNT+. As such, we use a combined approach of steady state optical spectroscopy and 19F NMR studies. Optical spectroscopy allows to track the excitonic absorption quenching and trion signature due to charge carrier density while correlating it to the concentration of carriers extracted from NMR experiments. This combined methodology allows for quantitative determination of a molar extinction coefficient for free carriers in semiconducting SWCNTs. This molar extinction coefficient can then be used in further studies to determine the yield and mobility of free carriers generated in a variety of samples and applications, for example at a heterojunction in photovoltaic devices, to determine quantitative charge transfer efficiencies and dynamics.
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2

Katayama, Kenji, Kei Kawaguchi, Yuta Egawa, and Zhenhua Pan. "Local Charge Carrier Dynamics for Photocatalytic Materials Using Pattern-Illumination Time-Resolved Phase Microscopy." Energies 15, no. 24 (December 16, 2022): 9578. http://dx.doi.org/10.3390/en15249578.

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We showed two demonstrations of the local charge carrier dynamics measurements of photocatalytic materials using our recently developed time-resolved phase-contrast microscopic technique combined with the clustering analyses. In this microscopic time-resolved technique, we observed the charge carrier dynamics via the refractive index change instead of the luminescence or absorption change, where we could often observe non-radiative charge carrier processes such as charge carrier trapping and non-radiative relaxation. By the clustering analyses of all the pixel-by-pixel responses, we could extract various different charge carrier dynamics because photocatalytic materials have inhomogeneity on surfaces and the charge carrier behavior depends on the local structure and species. Even for typical photocatalytic materials, titanium oxide and hematite, we could recognize various charge carrier dynamics, which cannot be differentiated by the general fitting procedure for the averaged time response. We could categorize the surface-trapped charge carriers (holes and electrons) and bulk carriers in the nanosecond to millisecond order, which indicates that this analytical procedure will play an important role in understanding the charge carrier dynamics for various photocatalytic materials.
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3

Galovic, Slobodanka, Katarina Djordjevic, Milica Dragas, Dejan Milicevic, and Edin Suljovrujic. "Dynamics of Photoinduced Charge Carrier and Photothermal Effect in Pulse-Illuminated Narrow Gap and Moderate Doped Semiconductors." Mathematics 13, no. 2 (January 14, 2025): 258. https://doi.org/10.3390/math13020258.

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When a sample of semiconducting material is illuminated by monochromatic light, in which the photon energy is higher than the energy gap of the semiconductor, part of the absorbed electromagnetic energy is spent on the generation of pairs of quasi-free charge carriers that are bound by Coulomb attraction. Photo-generated pairs diffuse through the material as a whole according to the density gradients established, carrying part of the excitation energy and charge through the semiconducting sample. This energy is indirectly transformed into heat, where the excess negatively charged electron recombines with a positively charged hole and causes additional local heating of the lattice. The dynamic of the photoexcited charge carrier is described by a non-linear partial differential equation of ambipolar diffusion. In moderate doped semiconductors with a low-level injection of charge carriers, ambipolar transport can be reduced to the linear parabolic partial differential equation for the transport of minority carriers. In this paper, we calculated the spectral function of the photoinduced charge carrier distribution based on an approximation of low-level injection. Using the calculated distribution and inverse Laplace transform, the dynamics of recombination photoinduced heat sources at the surfaces of semiconducting samples were studied for pulse optical excitations of very short and very long durations. It was shown that the photoexcited charge carriers affect semiconductor heating depending on the pulse duration, velocity of surface recombination, lifetime of charge carriers, and their diffusion coefficient.
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4

Juška, Gytis, Kęstutis Arlauskas, and Kristijonas Genevičius. "Charge carrier transport and recombination in disordered materials." Lithuanian Journal of Physics 56, no. 3 (October 17, 2016): 182–89. http://dx.doi.org/10.3952/physics.v56i3.3367.

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In this brief review the methods for investigation of charge carrier transport and recombination in thin layers of disordered materials and the obtained results are discussed. The method of charge carrier extraction by linearly increasing voltage (CELIV) is useful for the determination of mobility, bulk conductivity and density of equilibrium charge carriers. The extraction of photogenerated charge carriers (photo-CELIV) allows one to independently investigate relaxation of both the mobility and density of photogenerated charge carriers. The extraction of injected charge carriers (i-CELIV) is effective for the independent investigation of transport peculiarities of both injected holes and electrons in bulk heterojunctions. For the investigation of charge carrier recombination we proposed integral time-of-flight (TOF) and double-injection (DI) current transient methods. The methods allowed us to obtain the following significant results: to determine the reason of the conductivity dependence on electric field strength and temperature in the amorphous and microcrystalline hydrogenated silicon and π-conjugated polymers, the time dependent Langevin recombination, the impact of morphology on charge carrier mobility, the reason of reduced Langevin recombination in RR-PHT (regioregular poly(3-hexylthiophene))/PCBM (1-(3-methoxycarbonyl)propyl-1phenyl-[6,6]-methanofullerene) bulk heterojunction structures – 2D Langevin recombination; and to evaluate that the mobility of holes is predetermined by off-diagonal dispersion in poly-PbO.
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5

Roy, Palas. "Hot-carriers in organic photovoltaics." Pure and Applied Chemistry 93, no. 2 (January 28, 2021): 223–30. http://dx.doi.org/10.1515/pac-2020-1001.

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Abstract Photogenerated charge carriers in organic photovoltaics (OPVs) suffer relaxation and recombination losses. However, extracting these carriers at higher energy (‘Hot-carriers’) has been found to be effective to overcome such loss pathways and improve efficiency of OPVs. Excess energy and long delocalization length promotes hot-carrier escape from Coulombic attraction and dissociation into free charges. Here, I have reviewed the ways to generate hot-carriers and their extraction in organic backbones. In-depth understanding of their energetics and dynamics will help designing hot-carrier photovoltaics.
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6

Kumar, Krishan, and Maria Wächtler. "Unravelling Dynamics Involving Multiple Charge Carriers in Semiconductor Nanocrystals." Nanomaterials 13, no. 9 (May 8, 2023): 1579. http://dx.doi.org/10.3390/nano13091579.

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The use of colloidal nanocrystals as part of artificial photosynthetic systems has recently gained significant attention, owing to their strong light absorption and highly reproducible, tunable electronic and optical properties. The complete photocatalytic conversion of water to its components is yet to be achieved in a practically suitable and commercially viable manner. To complete this challenging task, we are required to fully understand the mechanistic aspects of the underlying light-driven processes involving not just single charge carriers but also multiple charge carriers in detail. This review focuses on recent progress in understanding charge carrier dynamics in semiconductor nanocrystals and the influence of various parameters such as dimension, composition, and cocatalysts. Transient absorption spectroscopic studies involving single and multiple charge carriers, and the challenges associated with the need for accumulation of multiple charge carriers to drive the targeted chemical reactions, are discussed.
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7

Lascialfari, A., P. Ghigna, and S. De Gennaro. "Susceptibility and Evidences of Charge Carriers Interaction above Tc in Nd1.85Ce0.15CuO4+δ." International Journal of Modern Physics B 13, no. 09n10 (April 20, 1999): 1151–56. http://dx.doi.org/10.1142/s0217979299001107.

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The charge carrier density plays a crucial role in the transition between normal and superconducting state in the copper-oxide superconductors. In Nd 1.85 Ce 0.15 CuO 4+δ sample, for charge carrier density n = nc≃ 0.07 the superconductivity sets in. In order to investigate the magnetic properties around nc, a set of magnetic susceptibility measurements in the temperature range 3-260K for samples with different charge carriers concentrations were realized. Magnetic susceptibility curves of Nd 1.85 Ce 0.15 CuO 4+δ revealed novel behavior well above the critical temperature T c: at fixed T ≥45 K , the susceptibility χ, reported as a function of the charge carrier density n, shows a peak around n=0.06 and drops to significantly lower values for n greater than 0.07, the value at which the samples become superconducting. The effective magnetic moment μeff shows the same behavior. The comparison of the present experimental results with recent transport ones gives evidence of a possible interaction between charge carriers above T c. The possibility that this effect could be due to a bipolarons-like mechanism of charge carriers interaction is discussed.
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8

Nagaya Wong, Narumi, Seung Kyun Ha, Kristopher Williams, Wenbi Shcherbakov-Wu, James W. Swan, and William A. Tisdale. "Robust estimation of charge carrier diffusivity using transient photoluminescence microscopy." Journal of Chemical Physics 157, no. 10 (September 14, 2022): 104201. http://dx.doi.org/10.1063/5.0100075.

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Transient microscopy has emerged as a powerful tool for imaging the diffusion of excitons and free charge carriers in optoelectronic materials. In many excitonic materials, extraction of diffusion coefficients can be simplified because of the linear relationship between signal intensity and local excited state population. However, in materials where transport is dominated by free charge carriers, extracting diffusivities accurately from multidimensional data is complicated by the nonlinear dependence of the measured signal on the local charge carrier density. To obtain accurate estimates of charge carrier diffusivity from transient microscopy data, statistically robust fitting algorithms coupled to efficient 3D numerical solvers that faithfully relate local carrier dynamics to raw experimental measurables are sometimes needed. Here, we provide a detailed numerical framework for modeling the spatiotemporal dynamics of free charge carriers in bulk semiconductors with significant solving speed reduction and for simulating the corresponding transient photoluminescence microscopy data. To demonstrate the utility of this approach, we apply a fitting algorithm using a Markov chain Monte Carlo sampler to experimental data on bulk CdS and methylammonium lead bromide (MAPbBr3) crystals. Parameter analyses reveal that transient photoluminescence microscopy can be used to obtain robust estimates of charge carrier diffusivities in optoelectronic materials of interest, but that other experimental approaches should be used for obtaining carrier recombination constants. Additionally, simplifications can be made to the fitting model depending on the experimental conditions and material systems studied. Our open-source simulation code and fitting algorithm are made freely available to the scientific community.
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9

Geiregat, Pieter, Christophe Delerue, Yolanda Justo, Michiel Aerts, Frank Spoor, Dries van Thourhout, Laurens Siebbeles, Guy Allan, Arjan Houtepen, and Zeger Hens. "A Phonon Scattering Bottleneck for Carrier Cooling in Lead-Chalcogenide Nanocrystals." MRS Proceedings 1787 (2015): 1–5. http://dx.doi.org/10.1557/opl.2015.595.

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ABSTRACTThe cooling dynamics of hot charge carriers in colloidal lead chalcogenide nanocrystals is studied by white light transient absorption spectroscopy. We demonstrate a transient accumulation of charge carriers at a high-energy critical point in the Brillouin zone. Using a theoretical study of the cooling rate in lead chalcogenides, we attribute this slowing down of charge carrier cooling to a phonon scattering bottleneck around this critical point. Our approach allows for the first ever determination of hot carrier cooling rates, relevant in e.g. modeling of multiple exciton generation.
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10

Katayama, Kenji, Tatsuya Chugenji, and Kei Kawaguchi. "Charge Carrier Trapping during Diffusion Generally Observed for Particulate Photocatalytic Films." Energies 14, no. 21 (October 26, 2021): 7011. http://dx.doi.org/10.3390/en14217011.

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Photo-excited charge carriers play a vital role in photocatalysts and photovoltaics, and their dynamic processes must be understood to improve their efficiencies by controlling them. The photo-excited charge carriers in photocatalytic materials are usually trapped to the defect states in the picosecond time range and are subject to recombination to the nanosecond to microsecond order. When photo-excited charge carrier dynamics are observed via refractive index changes, especially in particulate photocatalytic materials, another response between the trapping and recombination phases is often observed. This response has always provided the gradual increase of the refractive index changes in the nanosecond order, and we propose that the shallowly trapped charge carriers could still diffuse and be trapped to other states during this process. We examined various photocatalytic materials such as TiO2, SrTiO3, hematite, BiVO4, and methylammonium lead iodide for similar rising responses. Based on our assumption of surface trapping with diffusion, the responses were fit with the theoretical model with sufficient accuracy. We propose that these slow charge trapping processes must be included to fully understand the charge carrier dynamics of particulate photocatalytic materials.
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11

Gungor, Arif Can, Stefan M. Koepfli, Michael Baumann, Hande Ibili, Jasmin Smajic, and Juerg Leuthold. "Modeling Hydrodynamic Charge Transport in Graphene." Materials 15, no. 12 (June 10, 2022): 4141. http://dx.doi.org/10.3390/ma15124141.

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Graphene has exceptional electronic properties, such as zero band gap, massless carriers, and high mobility. These exotic carrier properties enable the design and development of unique graphene devices. However, traditional semiconductor solvers based on drift-diffusion equations are not capable of modeling and simulating the charge distribution and transport in graphene, accurately, to its full extent. The effects of charge inertia, viscosity, collective charge movement, contact doping, etc., cannot be accounted for by the conventional Poisson-drift-diffusion models, due to the underlying assumptions and simplifications. Therefore, this article proposes two mathematical models to analyze and simulate graphene-based devices. The first model is based on a modified nonlinear Poisson’s equation, which solves for the Fermi level and charge distribution electrostatically on graphene, by considering gating and contact doping. The second proposed solver focuses on the transport of the carriers by solving a hydrodynamic model. Furthermore, this model is applied to a Tesla-valve structure, where the viscosity and collective motion of the carriers play an important role, giving rise to rectification. These two models allow us to model unique electronic properties of graphene that could be paramount for the design of future graphene devices.
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12

Juška, G., N. Nekrašas, and K. Genevičius. "Investigation of charge carriers transport from extraction current transients of injected charge carriers." Journal of Non-Crystalline Solids 358, no. 4 (February 2012): 748–50. http://dx.doi.org/10.1016/j.jnoncrysol.2011.12.016.

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13

Jiang, Kangbo, Wenzhong Wang, Jun Wang, Tianyu Zhu, Lizhen Yao, Ying Cheng, Yue Wang, Yujie Liang, and Junli Fu. "Cu2O nanoparticles sensitize TiO2/CdS nanowire arrays to prolong charge carrier lifetime and highly enhance unassisted photoelectrochemical hydrogen generation with 4.3% efficiency." Dalton Transactions 49, no. 27 (2020): 9282–93. http://dx.doi.org/10.1039/d0dt01643h.

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Effective separation of charge carriers and substantial prolongation of charge carrier lifetime are two vital issues for a photoanode to achieve highly efficient photoelectrochemical (PEC) hydrogen generation.
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14

Yuan, Yang, Brian A. Gregg, and Marcus F. Lawrence. "Time-of-flight study of electrical charge mobilities in liquid-crystalline zinc octakis(β-octoxyethyl) porphyrin films." Journal of Materials Research 15, no. 11 (November 2000): 2494–98. http://dx.doi.org/10.1557/jmr.2000.0358.

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Time-of-flight measurements performed on micron-thick films of liquid-crystalline zinc octakis(β-octoxyethyl) porphyrin indicated that charge carriers possess significantly high drift mobilities, attaining approximately 0.01 cm2 V−1s −1 and 0.008 cm2 V−1s −1 for holes and electrons, respectively, at room temperature. Upon heating the samples from 300 to 420 K, causing the porphyrin to go from the solid-crystalline to the discotic mesophase, the mobilities did not decrease drastically, and remained at values slightly larger than half those observed at room temperature. Charge transport in this material conformed to the Scher–Montroll model, which attributes a distribution of hopping times to the propagation of the initially formed charged carrier packet. Analysis of the “universal” plots prescribed by this model yielded a dispersion factor of 0.5 for both charge carriers.
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15

Dilmurat, Rishat, Suryoday Prodhan, Linjun Wang, and David Beljonne. "Thermally activated intra-chain charge transport in high charge-carrier mobility copolymers." Journal of Chemical Physics 156, no. 8 (February 28, 2022): 084115. http://dx.doi.org/10.1063/5.0082569.

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Disordered or even seemingly amorphous, donor–acceptor type, conjugated copolymers with high charge-carrier mobility have emerged as a new class of functional materials, where transport along the conjugated backbone is key. Here, we report on non-adiabatic molecular dynamics simulations of charge-carrier transport along chains of poly (indacenodithiophene-co-benzothiadiazole), within a model Hamiltonian parameterized against first-principles calculations. We predict thermally activated charge transport associated with a slightly twisted ground-state conformation, on par with experimental results. Our results also demonstrate that the energy mismatch between the hole on the donor vs the acceptor units of the copolymer drives localization of the charge carriers and limits the intra-chain charge-carrier mobility. We predict that room-temperature mobility values in excess of 10 cm2 V−1 s−1 can be achieved through proper chemical tuning of the component monomer units.
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16

Lukyanova, Lidia N., Vsevolod A. Kutasov, Piotr P. Konstantinov, and Valeri V. Popov. "Improved Thermoelectrics Based on Bismuth and Antimony Chalcogenides for Temperatures below 240 K." Advances in Science and Technology 74 (October 2010): 77–82. http://dx.doi.org/10.4028/www.scientific.net/ast.74.77.

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Thermoelectric and galvanomagnetic properties for solid solution based on bismuth and antimony chalcogenides were studied for the optimal compositions and carrier concentrations in the temperature interval 100-240 K. Galvanomagnetic properties were analyzed in the framework of the many–valley energy spectrum model with isotropic and anisotropic scattering of charge carries. The figure-of-merit is shown to be determined with optimal relations between the values of the density-of-states effective mass, the carrier mobility taking into account degeneration of charge carriers, and the lattice thermal conductivity. The figure-of-merit also depends on anisotropy of the constant energy surface and scattering mechanism. Average values of the figure-of-merit <Z> through the temperature interval 100-240 K are equal to (2.5-2.65) 10-3 K1 for optimal compositions and carrier concentrations.
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17

Dzhumanov, S. "METAL-INSULATOR TRANSITIONS IN DOPED La-BASED SUPER CONDUCTORS WITH SMALL-RADIUS DOPANTS." Eurasian Physical Technical Journal 19, no. 1 (39) (March 28, 2022): 15–19. http://dx.doi.org/10.31489/2022no1/15-19.

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n this work, we study the possibility of realizing two distinct mechanisms of metal-insulator transitions in hole-doped cuprates induced by the localization of charge carriers near the small-radius impurities and in a deformable lattice (i.e. in the absence of impurities). The purpose of this research is to determine the criteria (i.e. conditions) for the existence of the localized states of hole carriers and solve the problem of metal-insulator transitions in La-based cuprates. The advantage of La-based cuprate versus other types of cuprates is that two distinct metal-insulator transitions in La-based cuprates driven by the strong carrier-impurity-phonon and carrier-phonon interactions occur simultaneously in a wider doping range from the lightly doped to heavily doping regime. We show that at very low doping, the separate levels of hole carriers localized near impurities and in a deformable lattice are formed in the charge-transfer gap of the cuprates. As the doping level increases towards underdoped region, the energy levels of such charge carriers start to form energy bands which gradually broaden with increasing doping. We propose a new two-carrier cuprate superconductor model for studying two distinct metal-insulator transitions occurring simultaneouslyin hole-doped La-based cuprate compounds. We demonstrate that when hole carriers reside in impurity and polaron bands, these metal-insulator transitions in La-based superconductors with small-radius dopants occur accordingly in a wide doping range and relatively lower doping levels.
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18

Карамов, Д. Д., А. Н. Лачинов, C. А. Пшеничнюк, А. А. Лачинов, A. Ф. Галиев, А. Р. Юсупов, and С. Н. Салазкин. "Допирование несопряженного полимера органическим соединением с двумя устойчивыми энергетическими состояниями." Журнал технической физики 91, no. 5 (2021): 874. http://dx.doi.org/10.21883/jtf.2021.05.50702.285-20.

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We investigate the effect of doping by a small-molecular-weight organic compound phenolphthalein of non-conjugated polymer polydiphenylenephthalide. It is known that phenolphthalein has two energetically stable states - neutral and charged, as a result of the capture of an excess electron. The morphology of polymer films surfaces observed by atomic force microscopy. Analysis of the current-voltage characteristics showed that an increase of the dopant concentration leads to an increase in conductivity. Mounted connection nontrivial fact conductivity growth and mobility of charge carriers with increasing dopant concentration. At same time, an increase in the concentration of the dopant does not lead to a significant change in the charge-carrier concentration.
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19

Карамов, Д. Д., А. Н. Лачинов, C. А. Пшеничнюк, А. А. Лачинов, A. Ф. Галиев, А. Р. Юсупов, and С. Н. Салазкин. "Допирование несопряженного полимера органическим соединением с двумя устойчивыми энергетическими состояниями." Журнал технической физики 91, no. 5 (2021): 874. http://dx.doi.org/10.21883/jtf.2021.05.50702.285-20.

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We investigate the effect of doping by a small-molecular-weight organic compound phenolphthalein of non-conjugated polymer polydiphenylenephthalide. It is known that phenolphthalein has two energetically stable states - neutral and charged, as a result of the capture of an excess electron. The morphology of polymer films surfaces observed by atomic force microscopy. Analysis of the current-voltage characteristics showed that an increase of the dopant concentration leads to an increase in conductivity. Mounted connection nontrivial fact conductivity growth and mobility of charge carriers with increasing dopant concentration. At same time, an increase in the concentration of the dopant does not lead to a significant change in the charge-carrier concentration.
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20

Shukri, Seyfan Kelil, and Lemi Demeyu Deja. "Charge Carriers Density, Temperature, and Electric Field Dependence of the Charge Carrier Mobility in Disordered Organic Semiconductors in Low Density Region." Condensed Matter 6, no. 4 (November 3, 2021): 38. http://dx.doi.org/10.3390/condmat6040038.

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We investigate the transport properties of charge carriers in disordered organic semiconductors using a model that relates a mobility with charge carriers (not with small polarons) hopping by thermal activation. Considering Miller and Abrahams expression for a hopping rate of a charge carrier between localized states of a Gaussian distributed energies, we employ Monte Carlo simulation methods, and calculate the average mobility of finite charge carriers focusing on a lower density region where the mobility was shown experimentally to be independent of the density. There are Monte Carlo simulation results for density dependence of mobility reported for hopping on regularly spaced states neglecting the role of spatial disorder, which does not fully mimic the hopping of charge carriers on randomly distributed states in disordered system as shown in recent publications. In this work we include the spatial disorder and distinguish the effects of electric field and density which are not separable in the experiment, and investigate the influence of density and electric field on mobility at different temperatures comparing with experimental results and that found in the absence of the spatial disorder. Moreover, we analyze the role of density and localization length on temperature and electric field dependence of mobility. Our results also give additional insight regarding the value of localization length that has been widely used as 0.1b where b is a lattice sites spacing.
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21

Bebenin, N. G., N. N. Loshkareva, Yu P. Sukhorukov, A. P. Nossov, R. I. Zainullina, V. G. Vassiliev, B. V. Slobodin, K. M. Demchuk, and V. V. Ustinov. "Charge carriers in La0.67−xYxBa0.33MnO3." Solid State Communications 106, no. 6 (May 1998): 357–61. http://dx.doi.org/10.1016/s0038-1098(98)00030-1.

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22

Pimbley, J. M. "Recombination of injected charge carriers." Solid-State Electronics 33, no. 11 (November 1990): 1333–38. http://dx.doi.org/10.1016/0038-1101(90)90105-n.

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23

Choquet, Isabelle, Pierre Degond, and Christian Schmeiser. "Hydrodynamic Model for Charge Carriers." Communications in Mathematical Sciences 1, no. 1 (2003): 74–86. http://dx.doi.org/10.4310/cms.2003.v1.n1.a7.

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24

Benetti, Daniele, and Federico Rosei. "A bridge for charge carriers." Nature Energy 4, no. 11 (November 2019): 910–11. http://dx.doi.org/10.1038/s41560-019-0499-7.

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25

Förner, Wolfgang, and Wolfram Utz. "Nonlinear Charge Carriers in Polyacetylene." Journal of Molecular Modeling 4, no. 1 (January 1998): 12–32. http://dx.doi.org/10.1007/s008940050067.

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26

Lee, Hyangsook, Maria Boile, and Sotirios Theofanis. "Modeling Carrier Interactions in an International Freight Transport System." International Journal of Information Systems and Supply Chain Management 7, no. 1 (January 2014): 15–39. http://dx.doi.org/10.4018/ijisscm.2014010102.

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This paper presents a novel multi-level hierarchical approach which models carrier interactions in international maritime freight transportation networks. Ocean carriers, land carriers and port terminal operators are considered. Port terminal operators, providing transportation services within a port complex, are regarded as a special type of the carrier, based on their behavior. The carriers make pricing and routing decisions at different parts of the multimodal network, having hierarchical relationships. Ocean carriers are regarded as the leaders in a maritime shipping market. Port terminal operators are the followers of ocean carriers as well as the leaders of land carriers. The individual carrier problem is formulated at each level using Nash equilibrium to find the optimal service charge and routing pattern for which each carrier obtains the greatest profit. Interactions among different types of carriers are captured in a three-level model. The concept of multi-leader-follower game is applied to a multi-level game. A numerical example is used to demonstrate the validity of the developed three-level model.
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27

Blackburn, Jeff, Martha Alejandra Hermosilla Palacios, Obadiah Reid, and Andrew Ferguson. "(Invited) Signatures of Charge Carrier (De)Localization in Semiconducting Single-Walled Carbon Nanotubes." ECS Meeting Abstracts MA2023-01, no. 10 (August 28, 2023): 1174. http://dx.doi.org/10.1149/ma2023-01101174mtgabs.

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Semiconducting single-walled carbon nanotubes (s-SWCNTs) are attractive materials for a variety of opto-electronic devices and applications due their strong and energetically tunable optical absorption, and high charge carrier mobilities that result from the delocalized nature of the π-electron system. To realize the full potential of s-SWCNTs in these applications, it is critical to understand the generation, transport, interfacial transfer, and recombination of free charge carriers (electrons and holes). As with many pi-conjugated semiconductors, there remain uncertainties regarding the degree of (de)localization for charge carriers generated in s-SWCNTs either through photogenerated exciton dissociation or through charge injection by adsorbed redox dopants or gating. In this presentation, I will compare the various signatures of charge carrier localization and delocalization that appear in spectroscopic and transport studies of s-SWCNTs in a variety of different environments and over several decades of carrier density. These comparisons help to elucidate the important roles of intrinsic and extrinsic factors on carrier (de)localization and the information that spectroscopic signatures in the visible, near-IR, and mid-IR can provide on such (de)localization.
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28

Mishchanka, Valery N. "First-principles modeling of electron-phonon scattering rates in graphene." Modern Electronic Materials 10, no. 3 (October 14, 2024): 177–84. http://dx.doi.org/10.3897/j.moem.10.3.134474.

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Graphene, which has a high mobility of charge carriers, which exceeds the mobility of charge carriers for all known materials, is currently considered as one of the most promising materials for the creation of new semiconductor devices. The results of modeling of electron scattering rates are presented for the acoustic and optical phonons in a single layer of graphene without a substrate for small values of energy, which do not exceed 1 eV. When modeling these rates, variants of both emission and absorption of phonons are considered. The obtained dependences of the charge carrier scattering rates will allow us to study the main characteristics of charge carrier transport in semiconductor structures containing graphene layers by modeling using the Monte Carlo method. Characteristics and parameters of graphene can be used to create new heterostructure devices with improved output characteristics.
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Stepanov N.P., Ivanov M.S., Stepanova L.E., and Vinogradova L.V. "Regularities of behavior of temperature dependences of resistivity of crystals of solid solutions (Bi-=SUB=-2-x-=/SUB=-Sb-=SUB=-x-=/SUB=-)Te-=SUB=-3-=/SUB=- (0&lt;x&lt;2)." Semiconductors 56, no. 9 (2022): 679. http://dx.doi.org/10.21883/sc.2022.09.54214.9839.

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It is shown that the change in the resistivity of crystals of solid solutions (Bi2-xSbx)Te3 (0&lt;x&lt;2) p-type in the temperature range preceding the onset of intrinsic conductivity is due not only to a change in the static relaxation time, the behavior of which in the temperature range from 80 to 300 K is determined mainly by carrier scattering on the vibrations of the crystal lattice, but also by changing the concentration of light holes. The latter is a consequence of the transition of charge carriers from the subzone of heavy holes to the subzone of light holes, as a result of which the concentration of light holes, which make the main contribution to electrical conductivity, decreases with increasing temperature. As a consequence, the plasmon energy proportional to the concentration of charge carriers also decreases with increasing temperature, and the energy of this transition, comparable to the plasmon energy, increases. In this regard, crystals (Bi2-xSbx)Te3 have a specific feature due to the convergence of the plasmon energy and the interband transition, which creates conditions for increasing the intensity of the electron-plasmon interaction. Keywords: thermoelectric materials, bismuth and antimony tellurides, resistivity, interband transitions, plasma of free charge carriers.
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30

Lykakh, V. A., and E. S. Syrkin. "Carriers Spectra of Functionalized Semiconducting Nanowire and Conformational Transition in Molecules." Ukrainian Journal of Physics 57, no. 7 (July 30, 2012): 710. http://dx.doi.org/10.15407/ujpe57.7.710.

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The tuning of the spectrum of semiconducting nanowires as a result of the functionalization by a layer of molecules with a conformational transition is investigated. The situation where the electric charge carrier induces the conformational transition with a change of the orientation of the intrinsic electric dipole moments of molecules is expected. The spectrum of a carrier and the parameters of the arising quantum well are determined by the derived self-consistent system of transcendent equations. The system includes the Schrödinger equation for a charge carrier, nonlinear equations for the intrinsic electric-dipole moments, the material equations de4scribing the interaction of an extra carrier in the nanowire and molecular electric dipoles. In a semiconductor nanowire, the hole and electron spectra are symmetric. It is shown that the layer of adsorbed molecules breaks this symmetry when themolecular dipoles create the conditions for a localization of carriers of only one kind, which depends on the charge sign and the orientation of dipoles. The functionalized nanowires can be used as a semiconductor rectifier.
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31

Kahmann, Simon, and Maria A. Loi. "Hot carrier solar cells and the potential of perovskites for breaking the Shockley–Queisser limit." Journal of Materials Chemistry C 7, no. 9 (2019): 2471–86. http://dx.doi.org/10.1039/c8tc04641g.

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32

Zolnikov, Konstantin, Evgeny Shmakov, Andrey Artemiev, and Larisa Prykina. "Modeling of radiation effects at the physical and technological level in the IET CAD." E3S Web of Conferences 592 (2024): 06025. http://dx.doi.org/10.1051/e3sconf/202459206025.

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The article considers the issues of energy distribution and use management by means of modeling changes in the electrophysical characteristics of semico nductor structures under the influence of static radiation. The change in the main electrical parameters of transistor structures is given, such as, change in the concentration of the main charge carriers, change in specific resistance, change in the mobility of charge carriers, change in threshold voltage, change in the lifetime of charge carriers. Also in the article within the framework of changing other parameters of transistors the following calculations are carried out: change in the slope of the drain-gate characteristic, change in the leakage current in the drain circuit, thermal generation current, surface leakage current, change in input resistance.
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33

Shamirzaev, Timur S., Victor V. Atuchin, Vladimir E. Zhilitskiy, and Alexander Yu Gornov. "Dynamics of Vacancy Formation and Distribution in Semiconductor Heterostructures: Effect of Thermally Generated Intrinsic Electrons." Nanomaterials 13, no. 2 (January 11, 2023): 308. http://dx.doi.org/10.3390/nano13020308.

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The effect of thermally generated equilibrium carrier distribution on the vacancy generation, recombination, and mobility in a semiconductor heterostructure with an undoped quantum well is studied. A different rate of thermally generated equilibrium carriers in layers with different band gaps at annealing temperatures forms a charge-carrier density gradient along a heterostructure. The nonuniform spatial distribution of charged vacancy concentration that appears as a result of strong dependence in the vacancy formation rate on the local charge-carrier density is revealed. A model of vacancy-mediated diffusion at high temperatures typical for post-growth annealing that takes into account this effect and dynamics of nonequilibrium vacancy concentration is developed. The change of atomic diffusivity rate in time that follows on the of spatial vacancy distribution dynamics in a model heterostructure with quantum wells during a high-temperature annealing at fixed temperatures is demonstrated by computational modeling.
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34

RAMADURAI, DINAKAR, TAKAYUKI YAMANAKA, YANG LI, MILANA VASUDEV, VISWANATH SANKAR, MITRA DUTTA, MICHAEL A. STROSCIO, TIJANA RAJH, and ZORAN SAPONJIC. "INTERACTIONS OF THz VIBRATIONAL MODES WITH CHARGE CARRIERS IN DNA: POLARON-PHONON INTERACTIONS." International Journal of High Speed Electronics and Systems 17, no. 02 (June 2007): 293–309. http://dx.doi.org/10.1142/s0129156407004515.

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This paper presents models and experimental measurements that shed light on THz-phonon mediated transport of polarons in biomolecules. Polaron transport in DNA has been considered recently in view of the expected derealization of charge carriers on a one-dimensional wire as well as the highly charged nature of DNA.1,2 An understanding of the electrical transport properties and THz-phonon interactions of biomolecules is important in view of DNA's potential applications both as electrically conductive wires and as structures that facilitate the chemically-directed assembly of massively integrated ensembles of nanoscale semiconducting elements into terascale integrated networks. Moreover, understanding these interactions provides information of the THz spectrum of vibrational modes in DNA. A primary focus of this paper is on charge transport in biomolecules using indirect-bandgap colloidal nanocrystals linked with biomolecules.3 Through a combination of theoretical and experimental approaches,4-7 this paper focuses on understanding the electrical properties and THz-frequency interactions of DNA. Moreover, this paper presents observed charge transport phenomena in DNA and discusses how these measurements are related to carrier scattering from the THz vibrational modes in DNA. Indeed, carrier transport in DNA is analyzed in light of theoretical calculations of the effects of THz-frequency phonon emission by propagating carriers, THz-frequency phonon absorption by propagating and trapped carriers, and effective mass calculations for specific sequences of the DNA bases.1-7 These studies focus on THz-phonon-mediated processes since an extra carrier on a one-dimensional chain minimizes its energy by forming an extended polaron, and since many biomolecules, including DNA, exhibit THz vibrational spectra.8 Accordingly, these calculations focus on THz-phonon-mediated processes. These results are discussed in terms of the role of THz-phonon-mediated charge trapping and detrapping effects near guanine-rich regions of the DNA as well as on the understanding and identification of DNA with specific base sequences that promote charge transport. As in previous studies, optical excitation is used to inject carriers into DNA wires. Moreover, this paper reports on the use of gel electrophoresis to study charge-induced cleavage of DNA and the related transport of charge in DNA. Phonon absorption and emission from polarons in DNA,9 is analyzed using parameters from the well-known Su-Schrieffer-Heeger Hamiltonian.
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35

Druzhinin, A. A. "Peculiarities of charge carriers transport in submicron Si-Ge whiskers." Functional materials 22, no. 1 (April 20, 2015): 27–33. http://dx.doi.org/10.15407/fm22.01.027.

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36

RAMADURAI, DINAKAR, TAKAYUKI YAMANAKA, MILANA VASUDEV, YANG LI, VISWANATH SANKAR, MITRA DUTTA, MICHAEL A. STROSCIO, TIJANA RAJH, ZORAN SAPONJIC, and SONG XU. "ENVIRONMENTAL EFFECTS INFLUENCING THE VIBRATIONAL MODES OF DNA: NANOSTRUCTURES COUPLED TO BIOMOLECULES." International Journal of High Speed Electronics and Systems 18, no. 01 (March 2008): 47–61. http://dx.doi.org/10.1142/s0129156408005126.

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The interactions of charges in DNA with the vibrational modes in DNA depend on the spectra of these vibrational modes. Using (a) the Su-Schrieffer-Heeger (SSH) Hamiltonian approach, (b) integrated structures of DNA and manmade nanostructures, and (c) gel electrophoresis techniques,1 the interaction between charges in DNA and the vibrational modes of DNA are investigated. As is well-known, DNA has a rich spectrum of modes in the THz spectral regime. The use of manmade nanostructures integrated with DNA facilitates the engineering of nanoscale systems useful in studying the role of environmental effects on the vibrational modes of DNA as well as the interaction of these modes with charge carriers in DNA. Among the DNA-based structures considered in this account are: B-DNA and Z-DNA strands related by a conformational change; and DNA molecules bound on one terminal to indirect bandgap semiconductor quantum dots. Gel electrophoresis is used as a tool for the analysis of carrier interactions in novel integrated DNA-manmade-nanostructure complexes, and models based on the SSH Hamiltonian2 are employed as a means of analyzing the interactions between the vibrational modes of DNA and charge carriers in DNA.3-4
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37

Kiermasch, David, Andreas Baumann, Mathias Fischer, Vladimir Dyakonov, and Kristofer Tvingstedt. "Revisiting lifetimes from transient electrical characterization of thin film solar cells; a capacitive concern evaluated for silicon, organic and perovskite devices." Energy & Environmental Science 11, no. 3 (2018): 629–40. http://dx.doi.org/10.1039/c7ee03155f.

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38

Rau, EI, and VNE Robinson. "A Novel Method for Contactless, Non Destructive Investigation of Semi Conductor Structures in the SEM." Microscopy and Microanalysis 3, S2 (August 1997): 495–96. http://dx.doi.org/10.1017/s1431927600009363.

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It is known that scanning a focussed laser beam across the surface of a semi conductor wafer, can produce a photon induced voltage (PIV) at electrically active sites. This technique depends upon the incident photons inducing charge carriers, both electrons and holes, on or just below the surface of the semi conductor. These charge carriers drift through the device until they are captured by a defect, at which stage they accumulate, producing a voltage at the surface. These voltages are only associated with a charge carrier capture site, which means that a voltage build up only occurs at a defect. This PIV technique has been used for contactless imaging of semiconductor wafers, allowing easy identification of electrically active sites such as crystallographic defects, imperfections and inhomogenieties on or just below the surface [1,2].Nothing in the above mechanism excludes the use of an electron beam to induce charge carriers and produce an electron induced voltage (EIV).
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39

Lachinov, Alexey N., Danfis D. Karamov, Azat F. Galiev, Sergey N. Salazkin, Vera V. Shaposhnikova, Tatiana N. Kost, and Alla B. Chebotareva. "Non-Conjugated Copoly(Arylene Ether Ketone) for the Current-Collecting System of a Solar Cell with Indium Tin Oxide Electrode." Polymers 15, no. 4 (February 13, 2023): 928. http://dx.doi.org/10.3390/polym15040928.

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The mechanism of charge carrier transport in the indium tin oxide (ITO)/polymer/Cu structure is studied, where thin films of copoly(arylene ether ketone) with cardo fluorene moieties are used. This copoly(arylene ether ketone) is non-conjugated polymer which has the properties of electronic switching from the insulating to the highly conductive state. The dependence on the polymer film thickness of such parameters as the potential barrier at the ITO/polymer interface, the concentration of charge carriers, and their mobility in the polymer is studied for the first time. The study of this system is of interest due to the proven potential of using the synthesized polymer in the contact system of a silicon solar cell with an ITO top layer. The parameters of charge carriers and ITO/polymer barrier are evaluated based on the analysis of current–voltage characteristics of ITO/polymer/Cu structure within the injection current models and the Schottky model. The thickness of the polymer layer varies from 50 nm to 2.1 µm. The concentration of intrinsic charge carriers increases when decreasing the polymer film thickness. The charge carrier mobility depends irregularly on the thickness, showing a maximum of 9.3 × 10−4 cm2/V s at 210 nm and a minimum of 4.7 × 10−11 cm2/V s at 50 nm. The conductivity of polymer films first increases with a decrease in thickness from 2.1 µm to 210 nm, but then begins to decrease upon transition to the globular structure of the films at smaller thicknesses. The dependence of the barrier height on polymer thickness has a minimum of 0.28 eV for films 100–210 nm thick. The influence of the supramolecular structure and surface charge field of thin polymer films on the transport of charge carriers is discussed.
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40

Schindler, Karl-Michael, and Marinus Kunst. "Sensitization and Charge Carrier Kinetics in ZnO Powders." Zeitschrift für Naturforschung A 43, no. 3 (March 1, 1988): 189–92. http://dx.doi.org/10.1515/zna-1988-0301.

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Abstract The influence of the excess charge carrier injection mechanism on the excess charge carrier dynamics in ZnO powder is investigated by contactless transient photoconductivity measurements. Excess charge carriers were produced by above bandgap light, subbandgap light and by injection from an adsorbed dye (Rhodamine B) after excitation of this dye. In all these cases the transient photoconductivity decay extends over a large time range but only after band-to-band excitation an appreciable decay is observed in the microsecond time range. The experimental results are discussed in particular with respect to photocatalysis.
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41

Du, Sichao, Juxin Yin, Hao Xie, Yunlei Sun, Tao Fang, Yu Wang, Jing Li, et al. "Auger scattering dynamic of photo-excited hot carriers in nano-graphite film." Applied Physics Letters 121, no. 18 (October 31, 2022): 181104. http://dx.doi.org/10.1063/5.0116720.

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Charge carrier scattering channels in graphite bridging its valence and conduction band offer an efficient Auger recombination dynamic to promote low energy charge carriers to higher energy states. It is of importance to answer the question whether a large number of charge carriers can be promoted to higher energy states to enhance the quantum efficiency of photodetectors. Here, we present an experimental demonstration of an effective Auger recombination process in the photo-excited nano-graphite film. The time-resolved hot carrier thermalization was analyzed based on the energy dissipation via the Auger scattering channels. We split the Auger recombination occurrence centered at 0.40 eV energy state into scattering and recombination parts, for characterizing the scattering rate in the conduction band and the recombination rate toward the valence band. The scattering time with respect to the energy state was extracted as 8 ps · eV−1, while the recombination time with respect to the energy state was extracted as 24 ps · eV−1. Our study indicates a 300 fs delay between the hot carrier recombination and generation, leading to a 105 ps−1 · cm−3 Auger scattering efficiency. The observed duration for the Auger recombination to generate hot carriers is prolonged for 1 ps, due to the hot carriers energy relaxation bottleneck with optical-phonons in the nano-graphite. The presented analytic expression gives valuable insights into the Auger recombination dynamic to estimate its most efficient energy regime for mid-infrared photodetection.
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42

Freund, Friedemann, Michael M. Masuda, and Minoru M. Freund. "Highly mobile oxygen hole-type charge carriers in fused silica." Journal of Materials Research 6, no. 8 (August 1991): 1619–22. http://dx.doi.org/10.1557/jmr.1991.1619.

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Some peculiar positive charge carriers are thermally generated in fused silica above 500 °C. These charge carriers appear to be positive holes, chemically O− states, probably arising from dissociation of peroxy defects. The charge carriers give rise to a pronounced positive surface charge which disappears upon cooling but can be quenched by rapid quenching from ≍800 °C. Reheating to ≍200 °C remobilizes these charge carriers and causes them to anneal below 400 °C. The generation of positive holes charge carriers may be important to understand failure mechanisms of SiO2 insulators.
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43

Tian, Yuan, Dong Yang, Yu Ma, Zhongwen Li, Jun Li, Zhen Deng, Huanfang Tian, Huaixin Yang, Shuaishuai Sun, and Jianqi Li. "Spatiotemporal Visualization of Photogenerated Carriers on an Avalanche Photodiode Surface Using Ultrafast Scanning Electron Microscopy." Nanomaterials 14, no. 3 (February 3, 2024): 310. http://dx.doi.org/10.3390/nano14030310.

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The spatiotemporal evolution of photogenerated charge carriers on surfaces and at interfaces of photoactive materials is an important issue for understanding fundamental physical processes in optoelectronic devices and advanced materials. Conventional optical probe-based microscopes that provide indirect information about the dynamic behavior of photogenerated carriers are inherently limited by their poor spatial resolution and large penetration depth. Herein, we develop an ultrafast scanning electron microscope (USEM) with a planar emitter. The photoelectrons per pulse in this USEM can be two orders of magnitude higher than that of a tip emitter, allowing the capture of high-resolution spatiotemporal images. We used the contrast change of the USEM to examine the dynamic nature of surface carriers in an InGaAs/InP avalanche photodiode (APD) after femtosecond laser excitation. It was observed that the photogenerated carriers showed notable longitudinal drift, lateral diffusion, and carrier recombination associated with the presence of photovoltaic potential at the surface. This work demonstrates an in situ multiphysics USEM platform with the capability to stroboscopically record carrier dynamics in space and time.
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44

Du, Luchao, Xiaoping Shi, Menghan Duan, and Ying Shi. "Pressure-Induced Tunable Charge Carrier Dynamics in Mn-Doped CsPbBr3 Perovskite." Materials 15, no. 19 (October 8, 2022): 6984. http://dx.doi.org/10.3390/ma15196984.

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All-inorganic perovskite materials (CsPbX3) have attracted increasing attention due to their excellent photoelectric properties and stable physical and chemical properties. The dynamics of charge carriers affect the photoelectric conversion efficiencies of perovskite materials. Regulating carrier dynamics by changing pressure is interesting with respect to revealing the key microphysical processes involved. Here, ultrafast spectroscopy combined with high-pressure diamond anvil cell technology was used to study the generation and transfer of photoinduced carriers of a Mn-doped inorganic perovskite CsPbBr3 material under pressure. Three components were obtained and assigned to thermal carrier relaxation, optical phonon–acoustic phonon scattering and Auger recombination. The time constants of the three components changed under the applied pressures. Our experimental results show that pressure can affect the crystal structure of Mn-doped CsPbBr3 to regulate carrier dynamics. The use of metal doping not only reduces the content of toxic substances but also improves the photoelectric properties of perovskite materials. We hope that our study can provide dynamic experimental support for the exploration of new photoelectric materials.
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45

Ferguson, Andrew J., Justin Earley, Martha Alejandra Hermosilla Palacios, Tucker Murrey, Marissa Martinez, Garry Rumbles, Alexander Spokoyny, Obadiah Reid, and Jeff Blackburn. "(Invited) Probing Charge Carrier-Induced Changes in the Complex Dielectric Function in Carbon Nanotube Dispersions." ECS Meeting Abstracts MA2024-01, no. 9 (August 9, 2024): 895. http://dx.doi.org/10.1149/ma2024-019895mtgabs.

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The injection of charge carriers into pi-conjugated semiconductors, whether by electrochemical injection or chemical charge transfer, is a powerful approach to tune their electrical conductivity. Recently, the concept of dielectric catastrophe, where the charge carrier density is sufficiently large to significantly alter the intrinsic dielectric properties, has been demonstrated at high doping levels in organic semiconductor thin films. The observed increase in the dielectric constant leads to reduced coulombic interactions between charge carriers and the associated counterions, promoting enhanced free carrier generation and transport. Here, we employ a combination of steady state optical spectroscopy, quantitative 19F NMR studies, and microwave dielectric loss spectroscopy to probe charge carrier density and transport in doped single-walled carbon nanotube dispersions. We demonstrate that a similar dielectric catastrophe phenomenon can be observed even in isolated single-walled carbon nanotubes dispersed in a low dielectric constant solvent AND, perhaps more surprisingly, at carrier densities less than one carrier per nanotube. The precise details of the observed changes in complex dielectric function are dependent on the chemical structure of the charge-transfer dopant, with a near-instantaneous increase in the dielectric constant and electrical conductivity observed for low carrier densities using bulky benzyloxy-substituted icosahedral dodecaborane cluster dopants, DDBs. We attribute the observations to weak coulombic interactions between the injected charge carrier and the dopant counterion, along with the large polarizability afforded by the unique physicochemical properties of single-walled carbon nanotubes. If time permits, we will show results from recent studies where we extend this approach to the doping of other nanocarbons.
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46

Zmeskal, Oldrich, Jan Pospisil, Jakub Altsmid, and Stanislav Nespurek. "Barrier Properties of Printed Composite Zinc Phthalocyanine/Fullerene Sandwiched between Indium Tin Oxide and Alluminium Electrodes." Applied Mechanics and Materials 377 (August 2013): 156–60. http://dx.doi.org/10.4028/www.scientific.net/amm.377.156.

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TO/ZnPcSu-PCBM/Al heterostructure was prepared by ink-printing and studied by DC (current-voltage characteristics) and AC (dielectric spectroscopy) techniques (ZnPcSu means 3-diethylamino-1-propylsulphonamide substituted Zn phthalocyanine, PCBM phenyl-C61-butyric acid-methylester fullerene). At the Al contact a Schottky barrier was formed. To explain the shape of current-voltage characteristic two effects had to be taken into account, emission effect, overcoming the potential barrier effect, formed by the superposition of the image Coulombic, space-charge and external potentials, by charge carrier. Dielectric spectroscopy made possible to determine effective lifetime of charge carriers and characteristic time related to electron diffusion; lifetime of charge carriers was τd = 2.10-5 s, and the electron mobility was of order 104 cm2V-1s-1.
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47

Bochkareva N. I. and Shreter Y. G. "Space-Charge-Limited Efficiency of Electrically-Injected Carriers Localization." Physics of the Solid State 65, no. 1 (2023): 133. http://dx.doi.org/10.21883/pss.2023.01.54987.458.

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The mechanism for the influence of defects in theGaN on the efficiency of localization of electrically-injected charge carriers in the InGaN|GaN quantum well is studied using tunnel spectroscopy of deep centers. It is found that the curves of the quantum efficiency and the spectral efficiency of radiative recombination dependencies on forward bias have the shape with maximum and humps at the biases corresponding to the impurity bands of color centers in GaN. The quantum efficiency droop with increasing bias is accompanied by a blue shift of the emission spectrum. We explain these effects based on the model of carrier localization in the quantum well, which takes into account the significant contribution to the tunneling transparency of the potential walls of the quantum well from ionized deep centers and their recharging with increasing forward bias. Keywords: gallium nitride, quantum well, charge carrier localization, tunneling, quantum effeciency, color centers.
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48

Gokhfel’d, V. M., O. V. Kirichenko, and V. G. Peschanskii. "Acoustoelectronic size effects in metals (review)." Low Temperature Physics 19, no. 1 (January 1, 1993): 1–22. https://doi.org/10.1063/10.0033343.

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We consider acoustoelectronic phenomena in conductors with a high density of charge carriers under conditions when their mean free path compares to or exceeds the specimen thickness. In an external magnetic field, the scattering of electrons by the specimen boundary being close to the specular, a number of resonant and oscillatory effects occur that are due to the magneto-size quantization of the charge carrier energy or due to the effect of scattering at the conductor surface on their ballistics. These effects are analyzed over a wide range of acoustic frequencies for an arbitrary dispersion law of charge carriers. The oscillation period and the resonance magnetic field values contain more detailed information on the local characteristics of the Fermi surface as compared to acoustoelectronic phenomena in bulk specimens. Analysis of the smoothly (vs. H) varying part of the sound absorption decrement allows a detailed investigation into the dissipation mechanism in the system of electrons, which stems from their scattering by the specimen boundary. Acoustoelectronic phenomena have been analyzed for the condition of Andreev reflection of charge carriers by the normal metal–superconductor interface. Effect of the surface scattering of charge carriers on the electron-mediated transport of acoustic pulses is considered and the possibility is demonstrated of using a metal with open Fermi surfaces as a multiplier of sound pulses.
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49

Wang, Chenglong, Jiayi You, Miaomiao Gao, Peipei Zhang, Guoxiong Xu, and Hongjing Dou. "Bio-inspired gene carriers with low cytotoxicity constructed via the assembly of dextran nanogels and nano-coacervates." Nanomedicine 15, no. 13 (June 2020): 1285–96. http://dx.doi.org/10.2217/nnm-2020-0065.

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Aim: To achieve safe and biocompatible gene carriers. Materials & methods: A core/shell-structured hierarchical carrier with an internal peptide/gene coacervate ‘core’ and a dextran nanogel ‘shell’ on the surface has been designed. Results: The dextran nanogels shield coacervate (DNSC) can effectively condense genes and release them in reducing environments. The dextran nanogel-based ‘shell’ can effectively shield the positive charge of the peptide/gene coacervate ‘core’, thus reducing the side effects of cationic gene carriers. In contrast with the common nonviral gene carriers that had high cytotoxicities, the DNSC showed a high transfection efficiency while maintaining a low cytotoxicity. Conclusion: The DNSC provides an effective environmentally responsive gene carrier with potential applications in the fields of gene therapy and gene carrier development.
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50

SCHÖNENBERGER, CH, and S. F. ALVARADO. "PROBING SINGLE CHARGES BY SCANNING FORCE MICROSCOPY." Modern Physics Letters B 05, no. 13 (June 10, 1991): 871–76. http://dx.doi.org/10.1142/s0217984991001076.

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The scanning force microscopy is used to charge insulating films locally and to monitor the decay thereafter. On Si 3 N 4 films the charge decay shows up as a discontinuous staircase, demonstrating single charge carrier resolution. The decay is controlled by thermionic emission. The smallest charge amount transferred into a PMMA film was only one or two electrons. The imaged charge area showed no broadening with time, indicating that the excess carriers are immobile.
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