Home About us Contact
|
Home About us Contact | ||
|
|
||
Electrical Characteristics (electrical + characteristic)
Selected AbstractsElectrical Characteristics of an Electronic Control Device Under a Physiologic Load: A Brief ReportPACING AND CLINICAL ELECTROPHYSIOLOGY, Issue 3 2010DONALD M. DAWES M.D. Background:,Law enforcement officers use electronic control devices (ECDs), such as the TASER X26 (TASER International, Inc., Scottsdale, AZ, USA), to control resisting subjects. Some of the debate on the safety of the devices has centered on the electrical characteristics of the devices. The electrical characteristics published by TASER International have historically based on discharges into a 400 , resistor. There are no studies that the authors are aware of that report the electrical characteristics under a physiologic load. In this study, we make an initial attempt to determine the electrical characteristics of the TASER X26 during a 5-second exposure in human volunteers. Methods:,Subjects received an exposure to the dry, bare chest (top probe), and abdomen (bottom probe) with a standard TASER X26 in the probe deployment mode for 5 seconds. There were 10,11 pulse captures during the 5 seconds. Resistance was calculated using the sum of the absolute values of the instantaneous voltage measurements divided by the sum of the absolute values of the instantaneous current measurements (Ohm's Law). Results:,For the eight subjects, the mean spread between top and bottom probes was 12.1 inches (30.7 cm). The mean resistance was 602.3 ,, with a range of 470.5,691.4 ,. The resistance decreased slightly over the 5-second discharge with a mean decrease of 8.0%. The mean rectified charge per pulse was 123.0 ,C. The mean main phase charge per pulse was 110.5 ,C. The mean pulse width was 126.9 ,s. The mean voltage per pulse was 580.1 V. The mean current per pulse was 0.97 A. The average peak main phase voltage was 1899.2 V and the average peak main phase current was 3.10 A. Conclusions:,The mean tissue resistance was 602.3 , in this study. There was a decrease in resistance of 8% over the 5-second exposure. This physiologic load is different than the 400 , laboratory load used historically by the manufacturer. We recommend future characterization of these devices use a physiologic load for reporting electrical characteristics. We also recommend that all the electrical characteristics be reported. (PACE 2010; 33:330,336) [source] Development of microdevices for physioelectrical measurement of biological cellsELECTRONICS & COMMUNICATIONS IN JAPAN, Issue 1 2008Takanori Akagi Abstract Electrical characteristics of biological cells are important indices for obtaining information about the state and function of a cell. In this paper, we report the development of microdevices for physioelectrical measurement of cells by applying nano/microfabrication technologies. These devices enable the highly precise measurement of cell membrane potential and zeta potential of individual cells in a minimally invasive manner. Such a fusion of the microdevice technologies and biotechnologies is expected to provide power diagnostic tools for future cell study and cell therapy. © 2008 Wiley Periodicals, Inc. Electron Comm Jpn, 91(1): 40, 45, 2008; Published online in Wiley InterScience (www.interscience.wiley.com). DOI 10.1002/eej.10027 [source] Electrical characteristics of Al/polyindole Schottky barrier diodes.JOURNAL OF APPLIED POLYMER SCIENCE, Issue 5 2009Abstract In this study, the forward and reverse bias current,voltage (I,V), capacitance,voltage (C,V), and conductance,voltage (G/,,V) characteristics of Al/polyindole (Al/PIN) Schottky barrier diodes (SBDs) were studied over a wide temperature range of 140,400 K. Zero-bias barrier height ,B0(I,V), ideality factor (n), ac electrical conductivity (,ac), and activation energy (Ea), determined by using thermionic emission (TE) theory, were shown fairly large temperature dispersion especially at lower temperatures due to surface states and series resistance of Al/PIN SBD. I,V characteristics of the Al/PIN SBDs showed an almost rectification behavior, but the reverse bias saturation current (I0) and n were observed to be high. This high value of n has been attributed to the particular distribution of barrier heights due to barrier height inhomogeneities and interface states that present at the Al/PIN interface. The conductivity data obtained from G/,V measurements over a wide temperature range were fitted to the Arrhenius and Mott equations and observed linear behaviors for ,ac vs. 1/T and ln ,ac vs. 1/T1/4 graphs, respectively. The Mott parameters of T0 and K0 values were determined from the slope and intercept of the straight line as 3.8 × 107 and 1.08 × 107 Scm,1K1/2, respectively. Assuming a value of 6 × 1012 s,1 for ,0, the decay length ,,1 and the density states at the Fermi energy level, N(EF) are estimated to be 8.74 Å and 1.27 × 1020 eV,1cm,3, respectively. © 2009 Wiley Periodicals, Inc. J Appl Polym Sci, 2009 [source] Electrical characteristics of temperature-difference liquid phase deposited SiO2 on GaN with (NH4)2Sx treatmentPHYSICA STATUS SOLIDI (A) APPLICATIONS AND MATERIALS SCIENCE, Issue 11 2008Ming-Kwei Lee Abstract The characteristics of a SiO2 film grown on (NH4)2Sx treated GaN by temperature-difference liquid phase deposition were investigated. Hydrofluorosilicic acid and boric acid were used as deposition solutions. For GaN without the (NH4)2Sx treatment, an Al/SiO2/GaN MOS diode shows poor electrical characteristics due to the native oxides existing at the interface. With (NH4)2Sx treatment of GaN, a stable sulfide-terminated surface is obtained and the leakage current density of SiO2/GaN is improved from 6.15 × 10,4 A/cm2 to 2.08 × 10,5 A/cm2 at the electric field of 2 MV/cm. The effective oxide charges decrease from 6.09 × 1011 C/cm2 to 2.23 × 1011 C/cm2. (© 2008 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim) [source] Influence of laser shock waves on As implanted HgCdTePHYSICA STATUS SOLIDI (C) - CURRENT TOPICS IN SOLID STATE PHYSICS, Issue 4 2007V. Yakovyna Abstract The principal purpose of our research is to show that low-temperature treatment of materials can be successfully used instead of annealing. Laser shock waves (LSW) were chosen as an alternative to form p-n junctions in HgCdTe after arsenic ions were implanted. Electrical characteristics of As implanted HgCdTe bulk crystals were studied to determine the effect of LSW generated by nanosecond laser irradiation pulses. The samples were of n -type conductivity immediately after the implantation. Then LSW processing was performed under increasingly growing laser beam power density and shock wave pressure. The experiment demonstrated that a threshold shock wave pressure should be reached to ensure the p -to- n conductivity conversion in the surface layer of samples. On the whole the results provide evidence that LSW combined with ion implantation can be used to form p - n junctions in HgCdTe. (© 2007 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim) [source] Electrical properties of modified-grafted polypropyleneJOURNAL OF APPLIED POLYMER SCIENCE, Issue 6 2007Naeem M. El-Sawy Abstract The electrical properties of polypropylene (PP), grafted polypropylene (PP- g -PVP), and modified-grafted PVP with ,-cyano-,-(2-thienyl) crotononitrile were investigated. Also, the electrical characteristic of the modified-grafted PVP subjected to ,-irradiation (60 kGy) was studied. The results show that the , of trunk polymer undergoing different degree of grafting generally increases as function of the grafting yield. The grafting yield between 64.1 and 149% resulted in a progressive decrease in ,E, value. Inclusion of sulfur-containing substrate in different films, having various grafting yields, leads to both increase and decrease in , values. A significant increase in , values is observed upon inclusion of sulfur-containing substrate having maximum grafting yield (149%). These changes are accompanied by fluctuation in , values. The exposure of sulfur-containing substrate in grafting film to a dose of 60 kGy results in a significant decrease in ,E, values for the films undergoing a grafting yield between 64.1 and 149%. The observed changes in ,E, of different films investigated could be attributed mainly to corresponding changes in , values. The observed improvement in electrical properties is mainly because of possible increase in concentration of charge carrier and/or their mobilities. The scanning electron micrographs of some selected films show significant changes in the morphology of the films investigated due to changing the grafting yield, inclusion of sulfur-containing substrate, and exposure to ,-irradiation. © 2007 Wiley Periodicals, Inc. J Appl Polym Sci 104: 3797,3803, 2007 [source] Growth and electrical properties of flash evaporated AgGaTe2 thin filmsCRYSTAL RESEARCH AND TECHNOLOGY, Issue 2 2006B. H. Patel Abstract Thin films have been prepared by flash evaporation technique of a stoichiometric bulk of AgGaTe2 compound in vacuum and analysed using X-ray diffraction, transmission electron microscopy, selected area diffraction and energy dispersive analysis of X-rays. The effect of substrate temperature on the structural properties , grain size, film orientation, composition, and stoichiometry of the films have been studied. It was found that the polycrystalline, stoichiometric films of AgGaTe2 can be grown in the substrate temperature range of 473K < Ts < 573K. The influence of substrate temperature (Ts) on the electrical characteristics- Resistivity, Hall Mobility, Carrier concentration of AgGaTe2 thin films were studied. The electrical resistivity was found to decrease with increase in substrate temperature up to 573K and then increases. The variation of activation energy of AgGaTe2 thin films were also investigated. The implications are discussed. (© 2006 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim) [source] Novel modelling of residual operating time of transformer oilEUROPEAN TRANSACTIONS ON ELECTRICAL POWER, Issue 4 2003M. A. A. Wahab This paper presents techniques developed to accurately model the characteristics of transformer oil for the purpose of predicting the effect of aging on these characteristics. Aging causes some of the transformer oil characteristics to violate the internationally specified limits. The purpose of this simulation is to develop alternative techniques to predict the operating time after which these characteristics would violate the limits. The results obtained from monitoring of twenty in-service power transformers for long period of operating time up to ten years have been implemented in developing the proposed models. The physical, chemical and electrical characteristics have been determined periodically by internationally specified testing methods. The patterns of violation sequence of the standard limits, against operating time, by different transformer oil characteristics have been revealed and the most common pattern has been determined. The definition of residual operating time (trot) of the different transformer oil characteristics has been introduced. The choice of transformer oil breakdown voltage trot to represent that of the transformer oil characteristics has been justified. Modelling of trot as a function of transformer oil breakdown voltage, total acidity and water content by multiple-linear regression has been proposed and verified. Also, polynomial regression model of trot as a function only of transformer oil breakdown voltage has been given. The accuracy and applicability of these models and the different modelling techniques have been discussed and proved. [source] Evolution of Electrical, Chemical, and Structural Properties of Transparent and Conducting Chemically Derived Graphene Thin FilmsADVANCED FUNCTIONAL MATERIALS, Issue 16 2009Cecilia Mattevi Abstract A detailed description of the electronic properties, chemical state, and structure of uniform single and few-layered graphene oxide (GO) thin films at different stages of reduction is reported. The residual oxygen content and structure of GO are monitored and these chemical and structural characteristics are correlated to electronic properties of the thin films at various stages of reduction. It is found that the electrical characteristics of reduced GO do not approach those of intrinsic graphene obtained by mechanical cleaving because the material remains significantly oxidized. The residual oxygen forms sp3 bonds with carbon atoms in the basal plane such that the carbon sp2 bonding fraction in fully reduced GO is ,0.80. The minority sp3 bonds disrupt the transport of carriers delocalized in the sp2 network, limiting the mobility, and conductivity of reduced GO thin films. Extrapolation of electrical conductivity data as a function of oxygen content reveals that complete removal of oxygen should lead to properties that are comparable to graphene. [source] Threshold Voltage Shifts in Organic Thin-Film Transistors Due to Self-Assembled Monolayers at the Dielectric SurfaceADVANCED FUNCTIONAL MATERIALS, Issue 6 2009Stefan K. Possanner Abstract Recently, it has been shown by several groups that the electrical characteristics of organic thin-film transistors (OTFTs) can be significantly influenced by depositing self-assembled monolayers (SAMs) at the organic semiconductor/dielectric interface. In this work, the effect of such SAMs on the transfer characteristics and especially on the threshold voltage of OTFTs is investigated by means of two-dimensional drift-diffusion simulations. The impact of the SAM is modeled either by a permanent space charge layer that can result from chemical reactions with the active material, or by a dipole layer representing an array of ordered dipolar molecules. It is demonstrated that, in both model cases, the presence of the SAM significantly changes the transfer characteristics. In particular, it gives rise to a modified, effective gate voltage Veff that results in a rigid shift of the threshold voltage, ,Vth, relative to a SAM-free OTFT. The achievable amount of threshold voltage shift, however, strongly depends on the actual role of the SAM. While for the investigated device dimensions, an organic SAM acting as a dipole layer can realistically shift the threshold voltage only by a few volts, the changes in the threshold voltage can be more than an order of magnitude larger when the SAM leads to charges at the interface. Based on the analysis of the different cases, a route to experimentally discriminate between SAM-induced space charges and interface dipoles is proposed. The developed model allows for qualitative description of the behavior of organic transistors containing reactive interfacial layers; when incorporating rechargeable carrier trap states and a carrier density-dependent mobility, even a quantitative agreement between theory and recent experiments can be achieved. [source] Detailed Characterization of Contact Resistance, Gate-Bias-Dependent Field-Effect Mobility, and Short-Channel Effects with Microscale Elastomeric Single-Crystal Field-Effect TransistorsADVANCED FUNCTIONAL MATERIALS, Issue 5 2009Colin Reese Abstract The organic field-effect transistor (OFET) has proven itself invaluable as both the fundamental element in organic circuits and the primary tool for the characterization of novel organic electronic materials. Crucial to the success of the OFET in each of these venues is a working understanding of the device physics that manifest themselves in the form of electrical characteristics. As commercial applications shift to smaller device dimensions and structure/property relationships become more refined, the understanding of these phenomena become increasingly critical. Here, we employ high-performance, elastomeric, photolithographically patterned single-crystal field-effect transistors as tools for the characterization of short-channel effects and bias-dependent parasitic contact resistance and field-effect mobility. Redundant characterization of devices at multiple channel lengths under a single crystal allow the morphology-free analysis of these effects, which is carried out in the context of a device model previously reported. The data show remarkable consistency with our model, yielding fresh insight into each of these phenomena, as well as confirming the utility of our FET design. [source] Direct Spectroscopic Evidence for a Photodoping Mechanism in Polythiophene and Poly(bithiophene- alt -thienothiophene) Organic Semiconductor Thin Films Involving Oxygen and Sorbed MoistureADVANCED MATERIALS, Issue 46 2009Jing-Mei Zhuo Direct infrared spectroscopic evidence has been obtained for photodoping of high mobility regioregular poly(3-alkylthiophene) and poly[2,5-bis(3-alkyllthiophen-2-yl) thieno (3,2-b)thiophene] with the attendant formation of hydroxide counter-ions. This reveals the central role of dissolved water, explains the key features of degradation of the electrical characteristics of organic semiconductors in the ambient (see figure), and points to possible strategies to further improve their stability. [source] Coupling electrical and mechanical effects in discrete element simulationsINTERNATIONAL JOURNAL FOR NUMERICAL METHODS IN ENGINEERING, Issue 2 2008M. Renouf Abstract When investigating the electrical characteristics of granular assemblies under dynamical solicitations (powder, steel bead assemblies, etc.), it is difficult to distinguish between effects that are purely electrical and those that are strongly dependent on mechanical effects. Although numerous experimental works have permitted better understanding of the static electrical behaviour of such media, it is difficult to determine the effects control the multi-physical behaviour of the medium, especially under dynamical solicitations. In the present paper, numerical investigations of the electrical characteristics of granular material are proposed. Moreover, it presents the formulation of a new model, embedded in the general scheme of discrete element methods, that couples electrical and mechanical effects and takes into account the oxidation phenomenon. Numerical simulations on the basis of experimental works are performed to validate the model, and the results of dynamical simulations are discussed. Copyright © 2007 John Wiley & Sons, Ltd. [source] Single-Crystal Polythiophene Microwires Grown by Self-Assembly,ADVANCED MATERIALS, Issue 6 2006H. Kim Single-crystal polythiophene microwires with unprecedented electrical characteristics such as low resistance (0.5,M,), a channel current as high as 25,,A, and well-resolved gate modulation (see figure) have been obtained by specific control over the supramolecular organization of individual polymer chains, which show preferential well-ordered interchain stacking along the wire axis. This approach offers a promising protocol for new flexible electronics. [source] Integrating electrical and aerodynamic characteristics for DFIG wind energy extraction and control studyINTERNATIONAL JOURNAL OF ENERGY RESEARCH, Issue 12 2010Shuhui Li Abstract A doubly fed induction generator (DFIG) wind turbine depends on the control of the system at both generator and turbine levels, and the operation of the turbine is affected by the electrical characteristics of the generator and the aerodynamic characteristics of the turbine blades. This paper presents a DFIG energy extraction and control study by combining the two characteristics together in one integrative environment to examine various factors that are critical for an optimal DFIG system design. The generator characteristics are examined for different d-q control conditions, and the extracted power characteristics of the turbine blades versus generator slip are presented. Then, the two characteristics are analyzed in a joint environment. An integrative study is conducted to examine a variety of parametric data simultaneously for DFIG maximum wind power extraction evaluation. A close-loop transient simulation using SimPowerSystem is developed to validate the effectiveness of steady-state results and to further investigate the wind energy extraction and speed control in a feedback control environment. Copyright © 2009 John Wiley & Sons, Ltd. [source] Critical Electric Field Strengths of Onion Tissues Treated by Pulsed Electric FieldsJOURNAL OF FOOD SCIENCE, Issue 7 2010Suvaluk Asavasanti Abstract:, The impact of pulsed electric fields (PEF) on cellular integrity and texture of Ranchero and Sabroso onions (Allium cepa L.) was investigated. Electrical properties, ion leakage rate, texture, and amount of enzymatically formed pyruvate were measured before and after PEF treatment for a range of applied field strengths and number of pulses. Critical electric field strengths or thresholds (Ec) necessary to initiate membrane rupture were different because dissimilar properties were measured. Measurement of electrical characteristics was the most sensitive method and was used to detect the early stage of plasma membrane breakdown, while pyruvate formation by the enzyme alliinase was used to identify tonoplast membrane breakdown. Our results for 100-,s pulses indicate that breakdown of the plasma membrane occurs above Ec= 67 V/cm for 10 pulses, but breakdown of the tonoplast membrane is above either Ec= 200 V/cm for 10 pulses or 133 V/cm for 100 pulses. This disparity in field strength suggests there may be 2 critical electrical field strengths: a lower field strength for plasma membrane breakdown and a higher field strength for tonoplast membrane breakdown. Both critical electric field strengths depended on the number of pulses applied. Application of a single pulse at an electric field up to 333 V/cm had no observable effect on any measured properties, while significant differences were observed for n,10. The minimum electric field strength required to cause a measurable property change decreased with the number of pulses. The results also suggest that PEF treatment may be more efficient if a higher electric field strength is applied for a fewer pulses. [source] Multidrug resistance modulator interactions with neutral and anionic liposomes: membrane binding affinity and membrane perturbing activityJOURNAL OF PHARMACY AND PHARMACOLOGY: AN INTERNATI ONAL JOURNAL OF PHARMACEUTICAL SCIENCE, Issue 5 2005Madeleine Castaing A variety of cationic lipophilic compounds (modulators) have been found to reverse the multidrug resistance of cancer cells. In order to determine the membrane perturbing efficacy and the binding affinity of such drugs in neutral and anionic liposomes, the leakage of Sulfan blue induced by five modulators bearing different electric charges was quantified using liposomes with and without phosphatidic acid (xEPA = 0 and 0.1), at four lipid concentrations. The binding isotherms were drawn up using the indirect method based on the dependency of the leakage rate on the modulator and the lipid concentrations. Upon inclusion of negatively charged lipids in the liposomes: (i) the binding of cationic drugs was favoured, except in a case where modulator aggregation occurred in the lipid phase; (ii) the drugs with a net electric charge greater than 1.1 displayed a greater enhancement in their potency to produce membrane perturbation; and (iii) the EPA effect on membrane permeation was due mainly to that on membrane perturbation (,50%) and, to a lesser extent, to that on the binding affinity (,50%). The present study provides evidence that drug-membrane interactions are the result of a complex interplay between the structural and electrical characteristics of the drugs and those of the membranes. [source] Improved Aging Characteristics of NTC Thermistor Thin Films Fabricated by a Hybrid Sol,Gel,MOD ProcessJOURNAL OF THE AMERICAN CERAMIC SOCIETY, Issue 1 2006Dmitry A. Kukuruznyak Negative temperature coefficient thermistor oxide thin films with improved aging characteristics are described. Better thermal stability has been achieved by incorporating sol,gel techniques with metallo-organic decomposition methods. A compositional range was identified whereby borosilicate may incorporate into the thermistor oxides, forming nanocomposites showing thermistor electrical characteristics. Thermistor thin films, with composition Ni0.48Co0.24Cu0.6Mn1.68O4·0.22SiO2·0.15B2O3 were deposited onto glass substrates from a solution containing organic transition metal salts, tetraethyl orthosilicate and triethyl borate. Electrical resistance measurements verified characteristic thermistor behavior. Nanocomposite thin films exhibited a factor of four improvement as compared with pure oxides after aging at 150°C for 500 h. [source] Electrical Characteristics of an Electronic Control Device Under a Physiologic Load: A Brief ReportPACING AND CLINICAL ELECTROPHYSIOLOGY, Issue 3 2010DONALD M. DAWES M.D. Background:,Law enforcement officers use electronic control devices (ECDs), such as the TASER X26 (TASER International, Inc., Scottsdale, AZ, USA), to control resisting subjects. Some of the debate on the safety of the devices has centered on the electrical characteristics of the devices. The electrical characteristics published by TASER International have historically based on discharges into a 400 , resistor. There are no studies that the authors are aware of that report the electrical characteristics under a physiologic load. In this study, we make an initial attempt to determine the electrical characteristics of the TASER X26 during a 5-second exposure in human volunteers. Methods:,Subjects received an exposure to the dry, bare chest (top probe), and abdomen (bottom probe) with a standard TASER X26 in the probe deployment mode for 5 seconds. There were 10,11 pulse captures during the 5 seconds. Resistance was calculated using the sum of the absolute values of the instantaneous voltage measurements divided by the sum of the absolute values of the instantaneous current measurements (Ohm's Law). Results:,For the eight subjects, the mean spread between top and bottom probes was 12.1 inches (30.7 cm). The mean resistance was 602.3 ,, with a range of 470.5,691.4 ,. The resistance decreased slightly over the 5-second discharge with a mean decrease of 8.0%. The mean rectified charge per pulse was 123.0 ,C. The mean main phase charge per pulse was 110.5 ,C. The mean pulse width was 126.9 ,s. The mean voltage per pulse was 580.1 V. The mean current per pulse was 0.97 A. The average peak main phase voltage was 1899.2 V and the average peak main phase current was 3.10 A. Conclusions:,The mean tissue resistance was 602.3 , in this study. There was a decrease in resistance of 8% over the 5-second exposure. This physiologic load is different than the 400 , laboratory load used historically by the manufacturer. We recommend future characterization of these devices use a physiologic load for reporting electrical characteristics. We also recommend that all the electrical characteristics be reported. (PACE 2010; 33:330,336) [source] The effect of oxygen remote plasma treatment on ZnO TFTs fabricated by atomic layer depositionPHYSICA STATUS SOLIDI (A) APPLICATIONS AND MATERIALS SCIENCE, Issue 8 2010Seungjun Lee Abstract We deposited ZnO thin films by atomic layer deposition (ALD) and then investigated the chemical and electrical characteristics after plasma treatment. The chemical bonding states were examined by X-ray photoelectron spectroscopy (XPS). The XPS spectra of O 1s showed that the intensity of oxygen deficient regions of the ZnO film decreased from 27.6 to 19.4%, while the intensity of the oxygen bound on the surface of the ZnO film increased from 15.0 to 21.9% as plasma exposure times increased. The ZnO film exhibited a decrease in carrier concentration from 4.9,×,1015 to 1.2,×,1014,cm,3 and an increase in resistivity from 1.2,×,102 to 9.8,×,103,,,cm as the plasma exposure times increased. To verify the changes in the chemical and electrical properties of the ZnO films caused by the oxygen remote plasma treatment, ZnO thin film transistors were fabricated and their electrical properties were investigated. We found that the Ion/Ioff ratio increased from 7.3,×,104 to 8.6,×,106, the subthreshold swings improved from 1.67 to 0.45,V/decade, and the saturation mobility (µsat) decreased from 1.63 to 0.72,cm2/V,s as plasma exposure times were increased. [source] On the mechanism of conductivity enhancement and work function control in PEDOT:PSS film through UV-light treatmentPHYSICA STATUS SOLIDI (A) APPLICATIONS AND MATERIALS SCIENCE, Issue 7 2010Abderrafia Moujoud Abstract In this work, we study the effect of UV light on the work function of PEDOT:PSS films. The authors found that UV irradiation lead to an increase in the work function. Several devices with UV exposed and unexposed PEDOT:PSS were fabricated and measured. The current,voltage characteristics have been obtained for ITO/PEDOT:PSS/InZnO samples. We found that UV irradiated devices show better electrical characteristics and lead to Ohmic contact. The trend in device performance was explained by the observed changes in the work function of the PEDOT:PSS layer. The change in the work function was measured by ultraviolet photoelectron spectroscopy. The structural and morphological properties of PEDOT:PSS films with and without UV treatment were investigated by X-ray photoelectron spectroscopy and atomic force microscopy techniques. The change in the work function of PEDOT:PSS is mainly due to the surface conformational change. The stability of devices with and without UV treatment has been investigated under normal environmental conditions. Electrical properties of the devices have been studied over a period of 30 and 60 days. The stability tests show that devices with UV treatment are more stable that those without UV treatment. [source] Electrical characteristics of temperature-difference liquid phase deposited SiO2 on GaN with (NH4)2Sx treatmentPHYSICA STATUS SOLIDI (A) APPLICATIONS AND MATERIALS SCIENCE, Issue 11 2008Ming-Kwei Lee Abstract The characteristics of a SiO2 film grown on (NH4)2Sx treated GaN by temperature-difference liquid phase deposition were investigated. Hydrofluorosilicic acid and boric acid were used as deposition solutions. For GaN without the (NH4)2Sx treatment, an Al/SiO2/GaN MOS diode shows poor electrical characteristics due to the native oxides existing at the interface. With (NH4)2Sx treatment of GaN, a stable sulfide-terminated surface is obtained and the leakage current density of SiO2/GaN is improved from 6.15 × 10,4 A/cm2 to 2.08 × 10,5 A/cm2 at the electric field of 2 MV/cm. The effective oxide charges decrease from 6.09 × 1011 C/cm2 to 2.23 × 1011 C/cm2. (© 2008 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim) [source] Surface treatments of indium-tin oxide substrates for polymer electroluminescent devicesPHYSICA STATUS SOLIDI (A) APPLICATIONS AND MATERIALS SCIENCE, Issue 15 2006Z. Y. Zhong Abstract In this work, three different sets of processing techniques (wet, dry, and combined treatments) were utilized to modify the surfaces of indium-tin oxide (ITO) substrates for polymer electroluminescent devices (PELDs), and the influence of surface treatments on the surface properties of ITO substrates were investigated by X-ray photoelectron spectroscopy (XPS), atomic force microscopy (AFM), contact angle, and four-point probe. The surface energies of ITO substrates were also calculated from the measured contact angles. Experimental results show that the surface properties of the ITO substrates strongly depend on the surface treatments. Oxygen plasma treatment effectively improves the ITO surface properties since plasma decreases the surface roughness and sheet resistance, improves the surface stoichiometry and wetting. Furthermore, the PELDs with the differently treated ITO substrates as hole-injecting electrodes were fabricated and characterized. We observe that the optical and electrical characteristics of devices are greatly influenced by the surface treatments on ITO substrates. Oxygen plasma treatment decreases turn-on voltage, increases brightness and efficiency, and thereby improves the device performance of PELDs. (© 2006 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim) [source] Improved electrical, optical, and structural properties of undoped ZnO thin films grown by water-mist-assisted spray pyrolysisPHYSICA STATUS SOLIDI (A) APPLICATIONS AND MATERIALS SCIENCE, Issue 10 2006L. Martínez Pérez Abstract Undoped ZnO thin films were prepared using the ultrasonic spray pyrolysis deposition technique with zinc acetylacetonate dissolved in N,N-dimethylformamide as the source materials solution. The addition of water mist in a parallel flux to the spray solution stream was also used during deposition of the films. The addition of water mist improved the electrical characteristics of the ZnO films. Fresh ZnO samples were then thermally annealed in a H2 reducing atmosphere. X-ray diffraction patterns show mainly the wurzite crystalline ZnO phase in the films. An electrical resistivity (, ) of around 2.7 × 10,2 , cm was measured at room temperature for the best undoped ZnO film. , is approximately one order of magnitude lower than the resistivities found in undoped ZnO films obtained by means of similar non-vacuum deposition techniques. (© 2006 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim) [source] The effect of oxygen content on the electrical characteristics of ZnOPHYSICA STATUS SOLIDI (B) BASIC SOLID STATE PHYSICS, Issue 5 2007E. S. Jung Abstract This work presents the influence of the variation of oxygen content in the ZnO films on their electrical characteristics. We applied the post-thermal annealing in N2 and air ambient to control the oxygen content of ZnO films, which improved crystallinity and optical properties of ZnO films. The oxygen concentration was measured by Auger electron spectroscopy and the electrical characteristics were obtained by Hall measurement in the van der Pauw configuration and transmission line method. As result, it was shown that the electron concentration varies from 1016 to 1021/cm3, while the resistivity from 10,3 to tens ohm-cm with respect to Zn/O concentration ratio. (© 2007 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim) [source] Alternating-current conductance and capacitance of a diamond diode in the presence of deep-level impuritiesPHYSICA STATUS SOLIDI (C) - CURRENT TOPICS IN SOLID STATE PHYSICS, Issue 2 2010Ana Rodrigues Abstract The alternating-current conductance and capacitance of a diamond film/aluminium diode was measured over the temperature range 230,330 K. Loss tangent curves for the frequency range 100 Hz,1 MHz exhibited three maxima. Doping of the CVD diamond was not uniform, indicating the presence of deep-level impurities. Results were analysed for the temperature range 230,270 K, at which it is possible to observe processes that are supposed to occur in grains and grain boundary regions of polycrystalline diamond. A loss tangent curve was simulated using an equivalent circuit model composed of resistances and capacitances corresponding to depletion regions and the bulk and of the electrical characteristics of the two phases of diamond. This model explicitly includes deep impurities. The curve-fitting parameters for the loss tangent plot demonstrate that at medium frequency (4 kHz, activation energy 0.2 eV) the bulk resistance is high (100 k,) and the maximum is related to the presence of microcrystals, which exhibit low conductivity. At high frequency (800 kHz, activation energy 0.5 eV) the bulk resistance is low (1 k,), suggesting that the maximum is associated with grain boundary regions. The low values of the relaxation times obtained (10,28 and 4×10,27 s) are justified. (© 2010 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim) [source] The effect of absorption layer of different quantum well arrangement on optoelectronic characteristics of nitride-based photovoltaic cells grown by MOCVDPHYSICA STATUS SOLIDI (C) - CURRENT TOPICS IN SOLID STATE PHYSICS, Issue S2 2009Y. K. Fu Abstract In this study, III-nitride solar cells with multi-quantum well (MQW) absorption layer were grown on sapphire substrates by metal organic chemical vapor deposition (MOCVD). The effect of different quantum well (QW) arrangement on optoelectronic characteristics of III-nitrides photovoltaic cells was investigated. It was found that the upper quantum well (QW) layer will dominate electroluminescence (EL) emission mechanism and the electrical characteristics of solar cell. The advantage of modulating the short-circuit current density (JSC) and open-circuit voltage (VOC) can be obtained by different arrangement of blue and green QW in MQW absorption layer. The optimum electrical characteristics of solar cell with a JSC of 0.30 mA/cm2, a VOC up to 1.51 V, fill factor (FF) as high as 0.601, and a series resistance (RS) of 9 , can be obtained by using MQW absorption layer. (© 2009 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim) [source] On dot and out of dot electrical characteristics of silicon oxide nanodots patterned by scanning probe lithographyPHYSICA STATUS SOLIDI (C) - CURRENT TOPICS IN SOLID STATE PHYSICS, Issue 4 2009Sabar D. Hutagalung Abstract Silicon oxide nanodot arrays were grown on pre-cleaned silicon (100) substrate by scanning probe nanolithography. In this study, a conductive AFM was used to fabricate nanoscale oxide dots in humidity controlled environment. The AFM is equipped with a nanotechnology software package providing the control of tip-sample voltage and tip motion according to pre-designed patterns. The surface topography and size of obtained patterns (diameter and height) were investigated by a noncontact AFM mode. A series of five silicon oxide nanodot array with diameter in the range of 146.05-247.65 nm and height 2.14-4.87 nm had been successfully fabricated. Meanwhile, a contact AFM mode was used to investigate the localized I-V characteristics on the dots and out of dot position. It was found, the on dot characteristics are highly nonohmic due to potential barrier interface between silicon oxide and silicon substrate. However, the out of dot characteristic is linear indicates an ohmic contact between AFM tip and sample. (© 2009 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim) [source] Direct growth of GaN on off-oriented SiC (0001) by molecular-beam epitaxy for GaN/SiC heterojunction bipolar transistorPHYSICA STATUS SOLIDI (C) - CURRENT TOPICS IN SOLID STATE PHYSICS, Issue 7 2005Y. Nakano Abstract Direct growth of GaN on misoriented 4H- and 6H-SiC (0001) Si-face substrates and electrical characteristics of n-GaN/p-SiC heterojunction mesa diodes are presented. GaN was grown by molecular-beam epitaxy (MBE) using elemental Ga and rf plasma-excited active nitrogen. SiC substrates misoriented 8° toward the [11-20] direction were used in this study. The surfaces of MBE-grown GaN layers have wavy features with peak-to-valley height of 30 nm. These features originated from the substrate misorientation. It was found that step bunching and large faceting along [01-10] and [10-10] directions occurred during the growth of GaN. Lowering the growth temperature suppresses large faceting, and results in reduction of the peak-to-valley height to 3 nm. However, the surface still has the same undulating features (on a smaller length scale). Mesa diodes were fabricated from the grown GaN layers. The correlation between the diode electrical characteristics and GaN growth conditions is discussed. (© 2005 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim) [source] Schottky diodes fabricated on cracked GaN epitaxial layer grown on (111) siliconPHYSICA STATUS SOLIDI (C) - CURRENT TOPICS IN SOLID STATE PHYSICS, Issue 7 2005Sung-Jong Park Abstract The planar Schottky diodes were fabricated, characterized and modelled to study the electrical characteristics of cracked GaN epitaxial layer on (111) silicon substrate. We deposited Ti/Al/Ni/Au as the ohmic metal and Pt as the Schottky metal. The ohmic contact resistivity was 5.51 × 10,5 ,·cm2 after annealing in N2 ambient at 700 °C for 30 s. The fabricated Schottky diode exhibited the barrier height of 0.7 eV and the ideal factor was 2.4. We got the cutoff wavelength at 360 nm, peak responsivity of 0.097 A/W at 300 nm, and UV/visible rejection ratio was about 104. The SPICE simulation with the circuit model, which was composed with one Pt/GaN diode and three parasitic diodes, showed good agreement with the experiment. (© 2005 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim) [source] | |||||||||||||||||||