bluuebunny/crossref_metadata_2025_split huggingface dataset:
Electrokinetic Assembly of Microsphere and Cellular Arrays
Authors: Ozkan Mihrimah , Esener Sadik C. , Bhatia Sangeeta N. 
Published: April 2011

AbstractWe have developed a novel electrochemical system for field assisted, fluidic assembly of objects on a microfabricated silicon substrate by means of electrical addressing. The principle of our technique is based on the movement of charged species in solution to oppositely charged electrodes, as seen commonly in electrophoresis. Here, charged species such as beads and cells are moved electrokinetically through an aqueous solution towards a charged electrode. Micro patterning of the electrodes allows localization of charged species. We present a theoretical framework to predict the electric potential for assembly and disassembly of spherical objects. We correlate theoretical predictions with the motion of negatively charged polystyrene beads of 20 μm diameter on 100 μm feature micro patterned substrates. In addition, we extended these results to arraying of 20-30 μm diameter live mammalian cells by means of electrical addressing. This technique has applications in creation of ‘active’ cellular arrays for cell biology research, drug discovery and tissue engineering.
Energy Level Alignment and Exciton Binding Energies Using Model Interfaces between Metals and Evaporable Organic Electroluminescent Materials
Authors: Alvarado Santos F. , Rieβ Walter 
Published: April 2011

ABSTRACTWe report on a scanning probe spectroscopy study of the electronic properties of model organic/metal interfaces. The experiments allow us to determine parameters that are critical in charge carrier injection and transport, as are the energy gap between positive and negative polaronic states and the height of the barrier for charge carrier injection at metal/organic interfaces. In combination with optical absorption measurements, we gauge the exciton binding energy, a parameter determining energy transport and electroluminescence efficiency. The study was performed on thin films of tris(8-hydroxyquinolato)aluminum (Alq3) deposited on clean and LiF-covered Au(111), and on N,N'-di(naphthalen-1-yl)-N,N'-diphenylbenzidine (NPB) on Ni(111) and substrates.
Synthesis and Characterisation of Polypyridine Derivatives: Towards Regioregular PPY
Authors: Horsburgh Lockhart E. , Monkman Andrew P. , Wang Changsheng , Bryce Martin R. 
Published: April 2011

ABSTRACTPoly(2,5-pyridinediyl) was prepared from 2-bromo-5-iodopyridine, by a method which combines organomagnesium and organonickel chemistry, and leads to the regioselective formation of poly(2,5-pyridinediyl) (rPPY). The product of the reaction was compared to conventional poly(2,5-pyridinediyl) (PPY), thus enabling us to estimate that rPPY consists of 84±6% head-to-tail linkages. Photophysical properties of rPPY were also measured, and found to be generally similar to those of PPY, although there are some significant differences.
Effects of Inserting Highly Polar Salts Between the Cathode and Active Layer of Bulk Heterojunction Photovoltaic Devices
Authors: Shaheen Sean E. , Brabec Christoph J. , Sariciftci N. Serdar , Jabbour Ghassan E. 
Published: April 2011

ABSTRACTThermal deposition of small amounts of various salts at the interface between the active layer and the aluminum cathode was shown to alter the performance of bulk heterojunction photovoltaic devices. LiF and LiBr were found to enhance the power conversion efficiency as compared to devices with no interfacial salt, but Cs and K compounds were found to severely diminish the device performance. It is suggested that the Li compounds preferentially align to produce a bulk dipole moment at the interface, whereas the Cs and K compounds do not.
Preparation of Diarylethene Substituted Polymer Films for Optical Recording
Authors: Cho Song Yun , Kim Eunkyoung 
Published: April 2011

ABSTRACTEffect of photo-irradiation on the color change of diarylethene polymer films was investigated. Diarylethene polymer films were prepared from photopolymerization of a radical curable mixture of diarylethene compound and a fluoroalkylacrylate containing a photo initiator. 1-[6'-(Methacryloxyethyloxycarbonyl)-2'-methylbenzo[b]thiophene-3'-yl]-2- (2"-methylbenzo[b]thiophene-3"-yl)hexafluorocyclopentene (MMBTF6) was synthesized from 2,3-bis(2-methylbenzo[b]thiophene-3-yl)hexafluorocyclopentene (BTF6) in three steps. 2,2,3,3-Tetrafluoro-1,4-butyldiacrylate (TFBDA) was synthesized from the corresponding diol and acryloyl chloride in the presence of a base. The photocurable mixture was coated on a substrate and subjected to antinic irradiation, to afforded homogeneous transparent film. A mask image was recovered on the film by a light of 365 nm and read by a visible light (λ > 700 nm) without destruction of the image. To erase the recorded image, a white light or a visible light was irradiated. Photochromic quantum yield and photo-induced refractive index change of the diarylethene bound polymer film were determined as 0.12 and 0.0006 respectively.
Synthesis and Optical Properties of a Novel Oligobipyridine
Authors: Fu Y. J. , Wong T.K.S. , Zhang H.X. , Wang G. M. , Hu X. , Gao Z.S. , Jiang M.H. 
Published: April 2011

ABSTRACTIn this paper, 5,5' –bis [ 4'– methyl- ( 2,2'– bipyridin– 4- yl)- ethyl ]- 2,2'– bipyridine (BMBPYBPY), a partially conjugated derivative of oligobipyridine, has been synthesized and found to show strong photoluminescence (PL). Compared with the pyridine-based conjugated polymers, the shortened conjugation length shifts the emission color from green to violet-blue. The effects of morphology on its PL properties have been studied. From its as-precipitated powder state, an emission peak at 418 nm can be observed. However the emission spectra from its diffused states such as doped in KBr, or dissolved in CHCl3, as well as from its amorphous film state fabricated by vacuum evaporation are more complex. Also carried out are preliminary electroluminescent studies. Single layer devices ITO/BMBPYBPY/Al do not emit although current can be observed prominently. Double layer devices ITO/TPD/ BMBPYBPY/Al show emissions both from TPD and BMBPYBPY.
Electrical Conduction Mechanism of Highly Transparent and Conductive ZnO Thin Films
Authors: Minami Tadatsugu , Suzuki Shingo , Miyata Toshihiro 
Published: April 2011

ABSTRACTIn this paper, we describe the underlying theory along with experiments concerning the electrical conductivity of transparent conducting ZnO films with a carrier concentration of 1019-1021 cm−3. The experimentally determined mobility as a function of carrier concentration in the range of 1019-1021 cm−3 could be quantitatively referenced to a theoretically calculated mobility that is dominated by not only grain boundary scattering but also ionized impurity scattering using the Brooks-Herring-Dingle theory with both degeneracy and nonparabolicity of the conduction band taken into account. Concerning nonparabolicity, the conduction band effective mass as a function of carrier concentration was theoretically analyzed and experimentally determined.
Bipolar Electrical Conductive Transparent Oxide, CuInO2
Authors: Yanagi Hiroshi , Ueda Kazushige , Ohta Hiromichi , Hirano Masahiro , Hosono Hideo 
Published: April 2011

ABSTRACTA transparent oxide semiconductor with delafossite structure, CuInO2, was found to exhibit both p-type and n-type conduction by doping of an appropriate impurity and tuning of proper film-deposition conditions. Thin films of Ca-doped or Sn-doped CuInO2 were prepared on -Al2O3 (001) single crystal substrates by pulsed laser deposition method. The films were deposited at 723 K in O2 atmosphere of 1.0 Pa for the Ca-doped films or 1.5 Pa for the Sn-doped films. The positive sign of the Seebeck coefficient demonstrated p-type conduction in the Ca-doped films, while the Seebeck coefficient of the Sn-doped films was negative indicating n-type conductivity. The electrical conductivities of Ca-doped and Sn-doped CuInO2 thin films were 2.8×10−3 S·cm−1 and 3.8×10−3 S·cm−1, respectively, at 300 K. The optical band gap of each film was estimated to be ∼3.9 eV. Since CuInO2 exhibited bipolarity in electrical conduction, transparent p-n homojunctions based on CuInO2 were fabricated on (111) surface of yttria-stabilized zirconia single-crystal substrates. The structure of the diode was In2O3:Sn / n-CuInO2:Sn / p-CuInO2:Ca / In2O3:Sn electrode on the substrate. The contact between the n-and p-type CuInO2 semiconducting oxides was found to be rectifying. The turn-on voltage was ∼1.8 V.
Electrical Characteristics of Doped and Undoped High Dielectric Constant BCTZ Thin Films
Authors: Yi Woo-Chul , Kalkur T. S. , Philofsky Elliott , Kammerdiner Lee 
Published: April 2011

ABSTRACTBa1−xCaxTi1-yZryO3 materials have very high dielectric constant (up to 30,000) in the bulk form. In this paper, we are presenting the electrical and structural characteristics of undoped and 0.4% Mg-doped Ba0.96Ca0.04Ti0.84Zr0.16O3 (BCTZ) thin films on Pt/Ti/SiO2/Si substrates. The BCTZ films were deposited by spin on metal-organic decomposition method and annealed at a temperature 600-900°C in oxygen environment. The annealed thin films were characterized by X-ray diffraction. The electrical characteristics of the annealed thin films were analyzed by capacitance–voltage and current–voltage measurements. The as-annealed thin films were post- annealed in nitrogen and oxygen environments and the effect of post-annealing on their electrical characteristics were also presented in conjunction with 0.4% Mg doping effect of BCTZ thin films for possible high dielectric constant material applications.
Phase Formation Kinetics in Sol-Gel Derived Strontium Bismith Tantalate
Authors: Sung Yun-Mo , Kwack Woo-Chul 
Published: April 2011

ABSTRACTPhase formation characteristics of Sr0.7Bi2.4Ta2O9 (SBT) powder, synthesized via sol-gel and pyrolysis process, was investigated by using thermal analysis. Each of the two exotherms, appearing in differential thermal analysis (DTA) scan curves, was identified as crystallization of fluorite phase and transformation of fluorite to aurivillius phase, respectively by using x-ray diffraction (XRD). By applying non-isothermal kinetic analyses to the DTA results, activation energy values for the formation of fluorite and aurivillius phases were determined as 192 and 375 kJ/mol, respectively and Avrami exponent values for each reaction were determined as 0.91 and 0.96, respectively. These activation energy and Avrami exponent values were discussed in detail to understand phase formation mechanism in SBT system.
Kinetic Analysis of PbTiO3 Phase Formation Via Diffusion Couple Method
Authors: Sung Yun-Mo , Kwack Woo-Chul 
Published: April 2011

ABSTRACTA detail kinetic analysis was performed on the PbTiO3 phase formation reaction occurring via PbO-TiO2 diffusion couple experiments. The diffusion model of Pb2+ and O2− ions was used to derive the kinetics equation of PbTiO3 phase formation reaction. From the parabolic kinetics between the thickness of PbTiO3 layer and time, the reaction rate constant for PbTiO3 formation was determined to be a function of the average diffusion coefficient of Pb2+ ions. By substituting the diffusion couple experimental results into the present kinetics equation, average diffusion coefficient values of Pb2+ ions in PbTiO3 layer were calculated according to temperature values. The activation energy value for the diffusion of Pb2+ ions was estimated for PbTiO3 formation using Arrhenius plot and the equation for the diffusion coefficient of Pb2+ ions was determined.
Microstructure and Physical Properties of Ferroelectric-gate Memory Capacitors with Various Buffer Layers
Authors: Caragianis-Broadbridge Christine , Han Jin-ping , Ma T. P. , Lehman Ann Hein , Zhu Wenjuan , Luo Zhijiong , Pechkis Daniel L. , Laube Bruce L. 
Published: April 2011

ABSTRACTThis paper reports the microstructure and physical properties of ferroelectric capacitors formed from SrBi2Ta2O9(SBT) layers on Si with various buffer layers including jet-vapor deposited silicon nitride, zirconium oxide, hafnium oxide and thermally grown silicon oxide. Results from cross-sectional transmission electron microscopy (X-TEM), energy dispersive spectroscopy (EDS), X-Ray diffraction (XRD), X-ray photoelectron spectroscopy (XPS) and non-contact atomic force microscopy (nc-AFM) data coupled with capacitance-voltage (C-V) and current- voltage (I-V) data indicate that both the microstructure and physical properties of SBT films deposited on silicon are dependent on the buffer layer material employed.
Abnormal Spectral Behavior of Trivalent Neodymium Ions in Potassium Yttrium Fluoride Crystals
Authors: Yang Chunlai , Bartolo Baldassare Di 
Published: April 2011

ABSTRACTNd3+ ions in KYF4 can occupy different sites. The energy transfer processes that take place between them are responsible for the unusual behavior of Nd3+. From the spectroscopic measurements at different temperatures we found an anomalous spectroscopic behavior in the low temperature range (20K - 100K). Based on an energy transfer model, we proposed an explanation to this abnormal behavior. We derived the formula to describe the deexcitation process and make a data fitting on our dynamic decay measurements.
Influence of Pressure on 5d → 4f Emission Transitions of Ce3+
Authors: Cunningham Garry B. , Shen Yongrong , Bray Kevin L. , Mendoza Ulisses R. Rodriguez 
Published: April 2011

ABSTRACTHigh pressure is used to tune the emission and band structure of the phosphors Ce3+:Lu2S3 and Ce3+:Lu2SiO5. A significant red shift of the broad 5d → 4f emission of Ce3+ was observed in both phosphors. In Ce3+:Lu2S3, we also observed a significant decrease in the emission intensity of Ce3+ and attribute the quenching to a pressure-induced electronic crossover of the Lu2S3 conduction bandedge with the emitting 5d state of Ce3+. In Ce3+:Lu2SiO5, two Ce3+ sites are present and we observed energy transfer from one site (Ce(2)) to the other (Ce(1)) at low pressure. At high pressure, the energy transfer ceases and emission is no longer observed from the Ce(1) site. We propose an exciton recombination model of the energy transfer process.
Divalent and Trivalent Europium Doped Alumina Waveguides Elaborated by Pulsed Laser Deposition
Authors: Minardi Anne , Garapon Claudine , Mugnier Jacques , Champeaux Corinne 
Published: April 2011

ABSTRACTEuropium doped alumina Al2O3optical waveguides were prepared by pulsed laser deposition (PLD) using a KrF laser. The targets were obtained by sintering doped powders synthesized by a sol-gel method. Depending on the oxygen pressure used during the deposition, Eu3+ (for 0.1 mbar) or Eu2+ (for 10−5 mbar) are obtained in the films. Two kinds of Eu2+ ions are present, with a 4f-5d broad excitation band peaking at 330 nm and emission bands located at 490 nm or 585 nm respectively. For Eu3+ doped films, the usual 5D0 to the 7FJ multiplets emission spectra were observed. The emission lines are strongly inhomogeneously broadened. Low temperature site selective fluorescence measurements were achieved in order to correlate the different Eu3+ sites observed with the structure of the films (amorphous or γ crystallized).
PL due to Discrete Gap Levels in Some Chalcogenide Glasses- A Configurational Coordinate Diagram Illustration
Authors: Bhat N. Asha , Sangunni K.S. , Rao K.S.R.K. 
Published: April 2011

ABSTRACTPhotoluminescence (PL) studies were carried out on a-Se and a few Ge20Se80−xBix and Ge20Se70−xBixTe10 bulk glassy semiconductors at 4.2 K with Ar+ laser as excitation source. While a-Se and samples with lesser at% of Bi show fine structured PL with a large Stokes shift, samples with higher at% of Bi did not show any detectable PL. The investigations show at least three radiative recombination transitions. Features extracted by deconvoluting the experimental spectra show that the discrete gap levels associated with the inherent coordination defects are involved in the PL transitions. Absence of PL in samples with higher Bi at% are explained on the basis of nonradiative transition mechanisms. Overall PL mechanism involving gap levels in chalcogenide glasses is illustrated with the help of a configurational coordinate diagram.
Enhancement of Cathodoluminescent Characteristic from CaTiO3:Pr3+, by Ga3+ Addition
Authors: Byun Jung-Woo , Lee Byung-Kyo , Kim Dong-Kuk , Kang Seong-Gu , Kang Seung-Youl , Suh Kyung-Soo 
Published: April 2011

ABSTRACTCaTiO3:Pr3+ as an oxide phosphor is expected to be applied for a field emission display(FED) due to its relatively high conductivity. For the practical use, however, the CL intensity of CaTiO3:Pr3+ has to be enhanced. We introduced Ga3+ as a co-activator into the phosphor and investigated the CL characteristics with various Ga3+ concentrations. The CL intensity of CaTiO3:Pr3+ was remarkably increased when Ti4+ atom was replaced by the Ga3+. When the Ga3+ concentration is 5 times of Pr3+ molar concentration, the emission intensity of the CaTiO3:Pr3+ phosphor with Ga3+ is about 5 times higher than Ga3+-free samples. So, it was concluded that the addition of Ga3+ is essential to enhance CL property at low voltage. We proposed the following mechanism that excitation into the host lattice leads to the formation of electrons in the conduction band and holes in the valence band. The electrons in the conduction band recombine with the holes trapped at Ga3+ and this energy is effectively transferred to Pr3+ ion, which gives its own characteristic red emission.
Luminescence of doped nanocrystalline ZnSe
Authors: Suyver J. F. , Wuister S. F. , van der Beek T. , Kelly J. J. , Meijerink A. 
Published: April 2011

ABSTRACTLuminescence of nanocrystalline ZnSe:Mn2+ and ZnSe:Cu2+ prepared via an organic chemical synthesis method are described. The spectra show distinct ZnSe, Mn2+ and Cu2+ related emissions, all of which are excited via the host lattice. The Mn2+ emission wavelength depends on the concentration of Mn2+incorporated into the ZnSe lattice, which is attributed to the presence of Mn2+ pair-states at higher concentrations. The ZnSe:Cu2+ luminescence was studied as a function of the crystal-size. Temperature-dependent photoluminescence spectra and photoluminescence lifetime measurements are also presented and the results are compared to those of Mn2+ and Cu2+ in bulk ZnSe.
Blue Room-Temperature Photoluminescence of AlN Films, Prepared by RF Magnetron Sputtering
Authors: Ligatchev V. , Yoon S.F. , Ahn J. , Zhang Q. , Rusli  , Chew K. , Zhgoon S. 
Published: April 2011

ABSTRACTPhoto luminescence (PL) signal from the aluminum nitride (AlN) films, excited by near UV (363.8 nm) laser has been measured at the room temperature. The AlN films are deposited by radio frequency (RF) sputtering of aluminum in argon-nitrogen-hydrogen gas mixture. Positions of the PL peaks maximums are influenced by the AlN preparation regimes. The analysis of the PL data is based on the results of the structural studies and electron spectrum investigations.
Structural and Optical Properties of ZnS:Mn Films Grown by Pulsed Laser Deposition
Authors: Yeung K. M. , Lu S. G. , Mak C. L. , Wong K. H. 
Published: April 2011

ABSTRACTHigh-quality manganese-doped zinc sulfide (ZnS:Mn) thin films have been deposited on various substrates using pulsed laser deposition (PLD). Effects of back-filled Ar pressure and substrate temperature on the structural as well as optical properties of ZnS:Mn films were studied. Structural properties of these films were characterized by X-ray diffraction (XRD) and scanning electron microscopy (SEM). Photoluminescence (PL) and optical transmittance were used to characterize the optical properties of these films. Our results reveal that ZnS:Mn films were polycrystalline with a mixed phase structure consisting of both wurtzite and zinc-blende structure. The ratio of these two structures was strongly depended on the change of substrate temperature. Low substrate temperature facilitated the formation of zinc-blende structure while the wurtzite phase became dominant at high substrate temperature. ZnS:Mn films with preferred wurtzite structure were obtained at a substrate temperature as low as 450°C. An orange-yellow emission band was observed at ∼590 nm. As the substrate temperature increased, the peak of this PL band shifted to a shorter wavelength. Furthermore, shifts in the absorption edge and the energy gap due to the change in substrate temperature were also observed. The variation in these optical properties will be correlated to their structural change.
Photoluminescence of multi-layer GeSi dots grown on Si (001)
Authors: Wan J. , Luo Y. H. , Jin G. L. , Jiang Z. M. , Liu J. L. , Liao X. Z. , Zou J. , Wang Kang L. 
Published: April 2011

ABSTRACTTemperature and power dependent photoluminescence measurements were carried out on the multi-layer structure of GeSi dots grown on Si(001) substrate by gas-source molecular beam epitaxy. The transfer of photon-induced carriers from wetting layers into the dots and the region near the dots was evidenced. Different power dependent behaviors of the photoluminescence peak position were observed for the dots and the wetting layer. Accordingly, type-II and type-I band alignments were proposed for the dots and the wetting layers, respectively. After annealing, the photoluminescence peaks from the dots and the wetting layers showed blueshift due to the atomic intermixing. For the samples annealed at temperature above 850°C for 5min, the band alignment of the dots changes from type-II to type-I.
SSRM and SCM observation of modified lateral diffusion of As, BF2 and Sb induced by nitride spacers.
Authors: Eyben P. , Duhayon N. , Stuer C. , Wolf I. De , Rooyackers R. , Clarysse T. , Vandervorst W. , Badenes G. 
Published: April 2011

ABSTRACTInitial studies (using Scanning Spreading Resistance Microscopy) on the lateral diffusion of B and As have shown an important influence of the thickness of oxy/nitride spacers. The latter phenomenon was tentatively ascribed to stress enhanced diffusion under the spacer region [1]. These studies have been complemented with Scanning Capacitance Microscopy (SCM) measurements, which confirm the SSRM-data. In fact both techniques shows a similar increase in lateral diffusion with increasing spacer thickness (∼ 0.2 nm/nm spacer thickness), whereby no effect is observed on the vertical diffusion. When using spacers with or without TEOS-liner, fairly similar enhancements could be seen. Micro-Raman and CBED stress measurements for these cases do however show a large reduction in stress when a TEOS-liner is used, suggesting that the correlation (at least to the final) stress is not really justified. A possible explanation could however be that the lateral diffusion occurs before the stress relaxation within the thermal treatment. In order to elucidate the diffusion mechanism (initial stress, interstitials, hydrogen incorporation, TED,..) we have expandedthe experimental matrix with a vacancy diffuser such as Sb and simulated the potential H-incorporation duringthe nitride deposition by a hydrogen anneal. Moreover we also have studied the impact of TED by splits with RTP-anneals before the nitride deposition.
Self-Diffusion in Intrinsic and Extrinsic Silicon Using Isotopically Pure 30Silicon Layer
Authors: Nakabayashi Yukio , Osman Hirman I. , Segawa Toru , Toyonaga Kazunari , Matsumoto Satoru , Murota Junichi , Wada Kazumi , Abe Takao 
Published: April 2011

ABSTRACTSilicon self–diffusion coefficients were measured in intrinsic and extrinsic silicon from870 to 1070°C using isotopically pure 30Si layer. 30Si diffusion profiles are determined by secondary ion mass spectrometry. The temperature dependence of intrinsic diffusion coefficient in bulk Si isobtained. Comparing it in heavily As-doped or B-doped Si, it is found that Si self-diffusion is entirely mediated by interstitialcy mechanism at lower temperatures below 870°C.