bluuebunny/crossref_metadata_2025 huggingface dataset:
Diagnosis and treatment of hepatic encephalopathy
Authors: Savlan Ilona , Liakina Valentina , Valantinas Jonas
Published: May 2013

Background. Hepatic encephalopathy (HE) is a neuropsychiatric complication of liver cirrhosis which symptoms may vary from imperceptible to severe ones. In recent years, there have been some changes of fundamental hepatic encephalopathy pathogenesis and treatment. The early HE on the stage of minimal hepatic encephalopathy (MHE) is rarely diagnosed and treatable condition worldwide and in Lithuania as well, however, this HE stage is responsible for the cognitive disorders which impair the quality of life of cirrhotic patients. According to resent data, MHE can be diagnosed in up to 70% of cirrhotic patients.
Aim. To evaluate new diagnostic and treatment strategies for HE and especially MHE for further use in clinical practice to cure the quality of life of cirrhotic patients and prevent clinical manifestation of HE.
Methods and materials. This article is based on relevant original publications and reviews in English (1991–2012) that were retrieved by a selective key word based search in the Medline and PubMed databases.
Results. It is recommended not to decrease an amount of proteins in food and consume products containing more branched-chain amino acids. Non-absorbable disaccharides (lactulose) are still the drugs of the first choice, though recent data show significant concerns about their effectiveness. Rifaximin is increasingly used all over the world for hepatic encephalopathy treatment. Other drugs for HE treatment are of secondary importance. Lactulose, probiotics are recommended for minimal hepatic encephalopathy treatment.
Diagnosis, especially of minimal hepatic encephalopathy, remains complicated. There are no reliable and validated blood indicators to establish minimal hepatic encephalopathy diagnosis, and to follow up treatment efficacy. Psychometric and neurophysiologic methods, visualisation methods are used more in scientific researches. Computerized methods, such as inhibitory control and critical flicker frequency tests, are also promising.
Conclusions. Further studies are necessary to design proper algorithms of hepatic encephalopathy diagnostic and treatment.
Low-Temperature Au–Au Bonding Using Nanoporous Au–Ag Sheets
Authors: Mimatsu Hayata , Mizuno Jun , Kasahara Takashi , Saito Mikiko , Nishikawa Hiroshi , Shoji Shuichi
Published: May 2013

In this study, we proposed low-temperature Au–Au bonding using nanoporous Au–Ag sheets, fabricated by dealloying a Au–Ag sheet in HNO3 solution, as a joint layer. The influence of the annealing temperature on the pore structure and chemical properties of the sheets was investigated. The chemical composition of the sheet was analyzed by X-ray photoelectron spectroscopy (XPS). It was found that the strength of Au–Au bonding with the nanoporous sheet increased. A sheet treated with liquid N2 was also tested; the strength of the Au–Au bond increased as a result of this low-temperature treatment.
Ag/Ni/Ag Multilayer Reflector for GaN-Based Vertical Light-Emitting Diode
Authors: Yum Woong-Sun , Jeon Joon-Woo , Sung Jun-Suk , Jin Sungho , Seong Tae-Yeon
Published: May 2013

We investigate the effect of Ni insertion on the electrical and thermal properties of Ag-based reflectors for GaN-based light emitting diodes (LEDs). It is shown that after annealing at 500 °C, the surface of Ag only sample becomes significantly roughened due to agglomeration, whereas the surface of Ni-inserted Ag sample get roughened with elongated Ag hillocks on an ∼100-nm-thick Ag film. The Ni-inserted Ag contacts show higher reflectance (at 460 nm) than the Ag only sample after annealing at 500 °C. The 500-°C-annealed Ni-inserted Ag samples exhibit lower specific contact resistance than the annealed Ag only contacts. LEDs fabricated with the 500-°C-annealed Ni-inserted Ag contact give lower forward-bias voltage and series resistance as compared to those of LEDs with the 500-°C-annealed Ag only contact. The LEDs with the 500-°C-annealed Ni-inserted Ag contact exhibit 18% higher light output power (at 20 mA) than the LEDs with the Ag only contacts annealed at 500 °C. Based on the X-ray photoelectron spectroscopy and scanning electron microscopy results, the temperature dependence of the electrical characteristics of the Ni-inserted Ag contacts is described and discussed.
Effects of Using a Ag Anode with a Co-evaporation Thin Film of MoOx and α-Naphthyl Diamine Derivative in Organic Light-Emitting Diode
Authors: Park Sang-Geon , Wang Haiying , Mori Tatsuo
Published: May 2013

We investigated the effects of using a Ag anode with the co-evaporation of molybdenum oxide (MoO
x
) and N,N '-bis(1-naphthyl)-N,N '-diphenyl-1,1'-diphenyl-1,4'-diamine (α-NPD). The current density of the device with a Ag anode and a co-evaporation thin film was the highest among the various devices used owing to a low sheet resistance and charge transport. We discussed the mobility and carrier density of the co-evaporation thin film as compared with the electrical properties of the α-NPD thin film. The device with a Ag anode achieved high electroluminescence (EL) efficiency due to the optical design. In particular, the device with a Ag anode and a co-evaporation thin film showed an approximately 55% higher current efficiency than that with indium–tin oxide (ITO) and a MoO
x
layer.
Cross-Sectional Transmission Electron Microscopy Analysis of Nanogap Electrode Fabricated by Atomic Force Microscope Local Oxidation
Authors: Moriya Rai , Ikenaga Eriko , Masubuchi Satoru , Machida Tomoki
Published: May 2013

We present a cross-sectional transmission electron microscopy (TEM) analysis of a nanogap electrode fabricated by atomic force microscope (AFM) local oxidation. We successfully visualized a nanogap structure composed of Al | Al-oxide | Al with an Al-oxide width of less than 100 nm. We measured the composition of aluminum and oxygen by in situ energy-dispersive X-ray spectroscopy (EDX), and showed that Al is fully oxidized by AFM local oxidation. Our findings demonstrate that the depth of the Al-oxide can be precisely controlled to create a nanogap electrode without damaging the underlying substrate layer.
Solution-Refined Method for Electrostatic Potential Distribution of Large-Scale Electron Optics
Authors: Lee Yen-Min , Li Jia-Han , Sheu Tony Wen-Hann , Tsai Kuen-Yu , Yen Jia-Yush
Published: May 2013

The solution-refined method is developed to solve electrostatic fields of the electron-beam direct-write lithography system. The prediction of accurate electron trajectories and the geometry of the developed photoresist patterns rely on high-resolution electrostatic fields in the whole system. Considering fabrication errors, such electrostatic fields cannot be solved using a cylindrical symmetry. Thus, this problem is a multiscale problem that requires a huge computer memory to solve. In our cases, the minimum number of grids of 1 nm length are applied and the total memory required approaches 75 Gbyte. Since the proposed solution-refined technique has a tradeoff with computational time, fewer central processing units (CPUs) are needed to solve this system because each CPU that solves the problem exceeds its available storage memory. The proposed technique can be used to solve the electron-beam direct-write lithography system at higher resolution and the problems exceed the available storage memory.
0.65Pb(Mg1/3Nb2/3)O3–0.35PbTiO3 Thick Films for High-Frequency Piezoelectric Transducer Applications
Authors: Uršič Hana , Levassort Franck , Holc Janez , Lethiecq Marc , Kosec Marija
Published: May 2013

The properties of 0.65Pb(Mg1/3Nb2/3)O3–0.35PbTiO3 (0.65PMN–0.35PT) thick films were studied for high-frequency piezoelectric transducer applications. The films were prepared by screen-printing a thick-film paste on platinized alumina substrates and subsequent sintering at 950 °C. The effective thickness-coupling factor of these films was close to 48%, which is comparable with bulk ceramics having the same compositions. Furthermore, simulations of two configurations representing one element of a high-frequency linear-array transducer (30 MHz) suggests that 0.65PMN–0.35PT thick-films in 50 Ω electrical matching environment improves the performance in comparison with standard Pb(Zr,Ti)O3 (PZT) compositions.
Theoretical and Experimental Analyses of Particle Trapping in a Capillary Tube Using a Flexural Acoustic Wave
Authors: Kim Eun-Sun , Kim Jin-Tae , Lee Min-Hwan , Kim Sung-Hyun , Hwang In-Kag
Published: May 2013

Acoustic trapping of particles in a capillary tube using a flexural acoustic wave was studied both theoretically and experimentally. Acoustic force potential was calculated using numerical simulation based on the finite element method. The distribution of particles which resulted from the force potential was categorized into four cases, depending on the physical properties of particles and fluid. Acoustic trapping was demonstrated using a robust, compact acoustic transducer, providing arbitrary interaction length. Theoretical estimation was successfully confirmed experimentally.
Transparent Thin Films Deposited onto Polyester Film Substrate by Radio Frequency Sputtering with a Poly(tetrafluoroethylene) Target
Authors: Seino Shou , Nagai Yuki , Kobayashi Masashi , Iwamori Satoru , Noda Kazuhiro
Published: May 2013

Improvement technologies for antireflection property of transparent plastic substrates are required in computer displays. Inorganic coatings have been used to reduce the surface reflection. We have already reported that fluorocarbon thin films sputtered with a poly(tetrafluoroethylene) (PTFE) target are transparent and can be used for an antireflection film, although the pristine PTFE plate used for the sputtering target is white. The fluorocarbon thin films were deposited onto a polyester (PET) film substrate by an rf sputtering, and characterized their optical properties. Elemental ratio, fluorine for carbon, of the thin films increased and degree of cross-linking of the thin films decreased with an increase of the rf power. Arithmetical surface roughness of the fluorocarbon thin films slightly increased with an increase of the rf power. Surface roughness of the fluorocarbon thin film affects the transmittance as well as the chemical structure of the thin film. To enhance the transparency, the diffuse transmittance should be suppressed, and flat surface thin films should be prepared by the sputtering at lower rf power and pressure.
Low-Temperature Solution Processable Electrodes for Piezoelectric Sensors Applications
Authors: Tuukkanen Sampo , Julin Tuomas , Rantanen Ville , Zakrzewski Mari , Moilanen Pasi , Lupo Donald
Published: May 2013

Piezoelectric thin-film sensors are suitable for a wide range of applications from physiological measurements to industrial monitoring systems. The use of flexible materials in combination with high-throughput printing technologies enables cost-effective manufacturing of custom-designed, highly integratable piezoelectric sensors. This type of sensor can, for instance, improve industrial process control or enable the embedding of ubiquitous sensors in our living environment to improve quality of life. Here, we discuss the benefits, challenges and potential applications of piezoelectric thin-film sensors. The piezoelectric sensor elements are fabricated by printing electrodes on both sides of unmetallized poly(vinylidene fluoride) film. We show that materials which are solution processable in low temperatures, biocompatible and environmental friendly are suitable for use as electrode materials in piezoelectric sensors.
A Printable Humidity Sensing Material Based on Conductive Polymer and Nanoparticles Composites
Authors: Lee Chang-Hung , Chuang Wen-Yu , Lin Shih-Hui , Wu Wen-Jong , Lin Chih-Ting
Published: May 2013

To monitor humidity, the polymer-based humidity sensing material has become an emerging candidate because of its low-cost and low-power characteristics. To implement polymer sensing materials, however, the fabrication capability and stability are major concerns. In this work, an inkjet printable humidity sensing material, poly(3,4-ethylenedioxythiophene):poly(styrene sulfonate) (PEDOT:PSS), is developed to improve the fabrication capability. Besides, different kinds of nanoparticles, SiO2 and aluminum zinc oxide (AZO), are also employed to enhance the stability and sensitivity to humidity sensing. Based on experimental results, the sensitivity can be improved by 100%; the stability can also be noticeably enhanced. To understand the sensing mechanism, X-ray diffraction (XRD), Fourier transforms infrared diffraction (FTIR), and photoluminescence (PL) spectrometer measurements are performed. Based on these material investigations, the sensing enhancement is due to physical adsorption of the blending nanoparticles. This work proposes a high sensitivity and low cost humidity sensing material for different applications.
Interfacial and Network Characteristics of Silicon Nanoparticle Layers Used in Printed Electronics
Authors: Männl Ulrich , Chuvilin Andrey , Magunje Batsirai , Jonah Emmanuel Ohieku , Härting Margit , Britton David Thomas
Published: May 2013

In printed electronics the use of semiconducting silicon nanoparticles allows more than the simple printing of conductive materials. It gives the possibility of fabricating robust and inexpensive, active and reactive components like temperature sensors which are shown as an example. In our approach high quality silicon nanoparticles with stable, essentially oxide-free surfaces are used to replace the pigment in water-based graphic inks, which on curing have unique semiconducting properties, arising from the transport of charge through a percolation network of crystalline silicon nanoparticles. In this study scanning electron microscopy (SEM) and high-resolution transmission electron microscopy (HRTEM) were employed to investigate the mesoscale structure of the particle network and, more importantly the structure of the interface between particles. An intimate contact between lattice planes of different particles was observed, without the presence of an intervening oxide layer.
Estimation of Gas Permeation Characteristics of Ultrahigh Barrier Edge Sealing Materials from Asymptotic Solution of Diffusion Equation
Authors: Shimada Toshihiro , Yanase Takashi , Nagahama Taro , Kanno Toshiyuki
Published: May 2013

Materials and structures for water vapor barrier sealing are now actively studied, as the commercialization of organic electronic devices has become a reality. In this paper, we focus on the edge sealing barriers, in which diffusion plays an essential role. In the past, the diffusion-limited gas barrier properties were analyzed in the steady-state approximation, which is never reached within the device lifetime in the application for organic electronics. We analyze them using a simple analytical model. The diffusion before reaching the steady state is a strongly non-linear process, as is well known, and the length scale of approximately 1–10 mm is very important when a practical polymer resin is used for the edge seal.
Preparation and Properties of Poly(phenazasiline) with Various Substituents
Authors: Hayashi Hideki , Nakao Hidenobu , Miyabayashi Takeshi , Murase Makoto
Published: May 2013

Poly(phenazasiline) (PPhenaz) with various substituents was prepared, and the substituent effect was discussed. PPhenaz was prepared by dehalogenative polycondensation of the corresponding dibromophenazasiline (Phenaz). The conductivity of an electrochemically doped PPhenaz film was 10-1–101 S cm-1. Using PPhenaz as a hole-transporting layer, a double layer electroluminescent (EL) device was fabricated. The properties of the EL device improved, when the substituent of PPhenaz was small. We also fabricated organic thin-film transistors (OTFTs) using PPhenaz films. The transistors showed p-type properties. The conductivity and the transistor properties were not dependent on the density of phenazasiline in PPhenaz, whereas the properties of PPhenaz-containing EL devices depended on the size of the substituent in PPhenaz.
Dual Emissive-Reflective Display Materials with Large Emission Switching Using Highly Luminescent Lanthanide(III) Complex and Electrochromic Material
Authors: Kanazawa Kenji , Nakamura Kazuki , Kobayashi Norihisa
Published: May 2013

Electroswitching of emission and coloration was achieved by a combination of a luminescent Eu(III) complex and an electrochromic molecule of diheptyl viologen (HV2+), in order to utilize them as novel display devices with dual emissive-reflective modes. The coloration was associated with the HV2+ electrochromism. Emission control was also achieved by the HV2+ electrochromism via intermolecular energy transfer from the excited state of the Eu(III) ion to the HV+. In order to improve ON–OFF contrast in emission, the emission quantum yield of Eu(III) complex were considerably improved using low vibrational phosphine oxide ligands, resulting in the large control of emission switching.
Generation of Protein Nanogradients by Microcontact Printing
Authors: Schwaab Daniel , Zentis Peter , Winter Silke , Meffert Simone , Offenhäusser Andreas , Mayer Dirk
Published: May 2013

High resolution lithography combined with microcontact printing (µCP) by means of polyolefine polymer (POP) stamps enabled to create protein gradient patterns. By this means, discrete purely biochemical gradients of extracellular matrix proteins were fabricated. It was possible to adjust independently both the size of elements of a protein pattern and the distance between them with sub 100 nm resolution. Adhesion of primary neurons and directed neuronal outgrowth were observed on these protein patterns. Cellular constituents such as filopodia adhere to different printed protein elements of the discontinuous gradient including features as small as 75 nm.
Preparation of a Functionally Graded Fluoropolymer Thin Film and Its Application to Antireflective Coating
Authors: Senda Kazuo , Matsuda Tsuyoshi , Kawanishi Takumi , Tanaka Kuniaki , Usui Hiroaki
Published: May 2013

Fluoropolymer thin films were prepared by the ion-assisted vapor deposition polymerization (IAD) of 2-(perfluorohexyl) ethylacrylate (Rf-6) under Ar ion irradiation. The ion acceleration voltage V
a largely affected the film characteristics. With increasing V
a, the adhesion strength between the film and the substrate improved, while the surface energy and the refractive index increased. To attain a high adhesion strength, a low surface energy, and a low optical reflectivity simultaneously, a functionally graded film was prepared by varying V
a from 300 to 0 V continually in the course of film growth. As a consequence, an antireflective coating with good adhesion and low surface energy was obtained. The optical reflectivity of a glass substrate was reduced from 4.9 to 0.55% at a wavelength of 400 nm by depositing a 100-nm-thick single-layer functionally graded fluoropolymer film. The surface energy of this film was 8.5 mJ/m2.
Roll-to-Roll Microimprinting Process for Indium Tin Oxide Layer Patterning
Authors: Ahn Byoung-Joon , Kim Ji-Youp , Ko Sung-Lim
Published: May 2013

Conventional indium tin oxide (ITO) layer patterning processes are problematic because they have limited efficiency. Many applications demand large-area, continuous processing with low costs and a high throughput. In order to overcome these problems, a continuous roll-to-roll (R2R) microimprinting process is proposed and demonstrated for the purpose of ITO layer patterning. Additionally, a series of experiments were conducted to investigate the influence of process parameters, i.e., the operating speed, the nip pressure and the tension of substrate, and the geometry, i.e., the width and height of the master patterns, on the imprinted patterns of ITO-coated polyethylene terephthalate substrates. The proper imprinting conditions are investigated and the mechanism of ITO patterning by imprinting process was suggested. It was found that the ITO-coated area can be electrically isolated through the imprinting process, by the accumulation of microcracks on ITO induced by the deformation.
Ultrasonic Bonding of Cone Bump for Integration of Large-Scale Integrated Circuits in Flexible Electronics
Authors: Shuto Takanori , Iwanabe Keiichiro , Noda Kazuhiro , Nakai Seiya , Asano Tanemasa
Published: May 2013

This paper reports that room-temperature bonding of LSI chips to metalization on a plastic film made of poly(ethylene naphthalate) (PEN) can be realized by ultrasonic bonding of a cone-shaped microbump made of Au. A 20-µm-pitch area array of cone-shaped Au microbumps was fabricated on a Si wafer by photolithography and electroplating. The counter electrode on the PEN film was composed of a Au (top)/Ni/Al (bottom) layered structure, where Ni and Au layers were deposited by electroless plating on Al interconnection. Bonding of 8,800 bump connections with 83.4 mΩ/bump has been achieved at room temperature.
Effects of Deposition Rate on the Properties of CuPc Thin Films and Solar Cells
Authors: Li Shuang , Chen Jianhong , Zhou Xiang
Published: May 2013

We investigated the effects of deposition rate on the properties of copper phthalocyanine (CuPc) thin films and the performance of CuPc/C60 heterojunction organic solar cells prepared by vacuum thermal evaporation method. We found that the organic solar cell with higher CuPc deposition rate (R
CuPc) of around 4.0 Å/s showed a larger short circuit current density of around 5.79 mA/cm2 and a higher power conversion efficiency of around 1.3%, which were about 1.8- and 2-times compared to those of the devices with R
CuPc of 0.1 Å/s, respectively. We also found that the CuPc single layer devices with higher R
CuPc exhibited a larger current density, which may be due to a higher mobility and lower trap density in CuPc thin films with higher R
CuPc.
Photopatterned Coatable Polarizer for Flexible Display
Authors: Yoon So-Ra , Yang Hye-Jin , Jeong Kwang-Un , Lee Myong-Hoon
Published: May 2013

We present a novel method to photopattern a thin-film polarizer from a photosensitive lyotropic chromonic liquid crystal (LCLC) solution based on perylene dye. The photosensitive LCLC solution was prepared by dissolving 20–30 wt % of amine-functionalized perylene chromonic dye in an acrylic acid solution containing a photoinitiator and a multifunctional monomer. The shear-coated film after UV irradiation under a photomask and a subsequent development process exhibited the maximum polarization efficiency, P = 98.3%, with 10 µm line-and-space maximum resolution. The structure of the resulting photopatterned thin-film polarizer was investigated using polarized optical microscopy (POM) and a NanoView® three-dimensional (3D) surface profiler.
Low-Temperature Fabrication of Dye-Sensitized Solar Cells Using Pre-Sintered TiO2 Aggregates
Authors: Yasuda Takashi , Yukita Masafumi , Furukawa Shoji
Published: May 2013

The low-temperature fabrication of photoelectrodes for flexible dye-sensitized solar cells was investigated using aggregates of TiO2 nanoparticles. These aggregates were prepared by grinding mesoporous TiO2 bulk ceramics, and the deposited films almost retained the mesoporous structures of the original ceramics. Photoelectrodes fabricated with the aggregates exhibited a short-circuit current density comparable to that for the high-temperature sintered films, when the film thickness was up to 4 µm. In thicker films, however, the current values did not increase with thickness. The electron diffusion length evaluated from steady-state measurements was much smaller than the value obtained for the high-temperature sintered films, implying the degradation of interparticle connection during the preparation of aggregates. It was also found that TiO2 submicron crystals incorporated into the photoelectrodes effectively improved the electron diffusion length as well as the light absorption coefficient.
Measurement Technology of Surface Potential Using Acoustic Wave and Electric Field
Authors: Kikunaga Kazuya , Yamashita Hiroshi , Fujii Yoshitaka , Nonaka Kazuhiro
Published: May 2013

We proposed a novel technique for measuring the surface potential of plastic films by detecting the electric field generated by charge oscillation. Charged polyamide films were vibrated by an acoustic wave at frequencies of up to 1 kHz, and the electric field was detected through a monopole antenna. Changes in the electric field caused by the vibration of the charged film indicate that the electric field was induced by charge oscillation. The surface potential and electrical polarity were related to the electric field intensity and phase, respectively. This method has the capability of detecting the surface potential at a longer distance than that for a surface potential sensor.
Formulation and Characterization of CuIn1-xGaxSe2 Ink for Gravure Offset Printing
Authors: Kim Inyoung , Han Hyun-Suk , Kwak Sun-Woo , Yu Jong-Su , Kim Bongmin , Jang Yunseok , Lee Taik-Min
Published: May 2013

CuIn1-x
Ga
x
Se2 (CIGS) paste for gravure offset printing was formulated by changing the amount of additives to determine the critical factor for gravure offset printing quality. With the addition of poly(vinyl pyrrolidone) (PVP), the viscosity and yield stress of CIGS ink decreased and shear thinning behavior disappeared. However, PVP effectively enhanced ink cohesion and elastic modulus, which critically affected the printability of the CIGS paste. Intense pulsed light (IPL) treatment in air made the microstructure of CIGS film denser without a phase change or oxidation. The gravure offset printing technique and IPL treatment were considered a good combination for a continuous and fast CIGS film growth process.
Dependence of the Carrier Transport Characteristics on the Buried Layer Thickness in Ambipolar Double-Layer Organic Field-Effect Transistors Investigated by Electrical and Optical Measurements
Authors: Zhang Le , Taguchi Dai , Manaka Takaaki , Iwamoto Mitsumasa
Published: May 2013

By using current–voltage (I–V) measurements and optical modulation spectroscopy, we investigated the dependence of the carrier behaviour on the film thickness of the buried pentacene layer in C60/pentacene ambipolar double-layer organic field-effect transistors (OFETs). It was found that the buried pentacene layer not only acted as a hole transport layer, but also accounted for the properties of the C60/pentacene interface. The hole and electron behaviour exhibited different thickness dependence on the buried pentacene layer, implying the presence of the spatially separated conduction paths. It was suggested that the injected holes transported along the pentacene/gate dielectric interface, which were little affected by the buried pentacene layer thickness or the upper C60 layer; while, the injected electrons accumulated at the C60/pentacene interface, which were sensitive to the interfacial conditions or the buried pentacene layer. Furthermore, it was suggested that the enhanced surface roughness of the buried pentacene layer was responsible for the observed electron behaviour, especially when d
pent>10 nm.
Organic Memory Transistors Using Monolayer of Semiconductor Colloidal Nano-Dots as a Floating Gate
Authors: Kajimoto Kaori , Matsui Daisuke , Uno Kazuyuki , Tanaka Ichiro
Published: May 2013

We fabricated pentacene-based memory field-effect transistors (FETs) in which a monolayer of semiconductor colloidal nano-dots (NDs) is embedded as a floating gate. After a sufficiently large writing voltage was applied on the control gate, the fabricated FETs showed a large positive threshold voltage (V
th) shift that was attributed to electrons trapped in embedded NDs. The V
th shift was measured as a function of the writing voltage, and it was shown that the minimum writing voltage for memory FETs with small NDs is significantly larger than that for FETs with large ones. This result supports the proposed model of the memory effect in which electrons that tunneled from nearby pentacene molecules are trapped in embedded NDs because the electron energy level in small NDs is higher than that in large ones.
Microscopic Characterization of Printable Low-Voltage Electrolyte-Gated Transistors by Electron Spin Resonance
Authors: Marumoto Kazuhiro , Tsuji Masaki , Yomogida Yohei , Takenobu Taishi , Iwasa Yoshihiro
Published: May 2013

We have investigated the microscopic properties of printable low-voltage electrolyte-gated transistors using electron spin resonance (ESR). The utilized devices were ion gel-gated regioregular poly(3-hexylthiophene) (RR-P3HT) thin-film transistors. We performed simultaneous mesurements of field-induced ESR (FI-ESR) and device characteristics using the same device. Clear FI-ESR signals due to hole carriers (positive polarons) were observed by applying a negative gate voltage. The anisotropy of the ESR linewidth indicated two-dimensional magnetic interactions between high density charges. The magnetism of the majority of hole carriers at a high charge density was found to be nonmagnetic from the simultaneous measurements of FI-ESR and transfer characteristics. The anisotropy of the g value of the ESR signal at a high gate voltage indicated the disordered molecular orientation of RR-P3HT where paramagnetic holes exist. These results provide insight into the charge transport mechanism of RR-P3HT polymer semiconductors with high charge densities.
Enhanced Performance of Dye-Sensitized Solar Cells with Nanostructure InN Compact Layer
Authors: Chen Cheng-Chiang , Chen Lung-Chien , Kuo Shu-Jung
Published: May 2013

This study presents a dye-sensitized solar cells (DSSCs) with a nanostructured InN compact layer (InN-CPL). The effect of a nanostructured InN-CPL in a DSSC structure prepared by radio frequency magnetron sputtering was examined. The InN-CPL effectively reduces the back reaction at the interface between the indium tin oxide (ITO) transparent conductive film and the electrolyte in the DSSC. DSSCs fabricated on ITO/InN-CPL/TiO2/D719 exhibited a short-circuit current density (J
SC), open-circuit voltage (V
OC), and power conversion efficiency (η) of 23.2 mA/cm2, 0.7 V, and 8.9%, respectively.
Fabrication of p-Type SnO Thin-Film Transistors by Sputtering with Practical Metal Electrodes
Authors: Hsu Po-Ching , Chen Wei-Chung , Tsai Yu-Tang , Kung Yen-Cheng , Chang Ching-Hsiang , Hsu Chao-Jui , Wu Chung-Chih , Hsieh Hsing-Hung
Published: May 2013

P-type thin-film transistors using polycrystalline tin monoxide (SnO) active layers were achieved by an industry-compatible sputtering technique with a SnO ceramic target. The SnO films clearly exhibited p-type conduction with the p-type Hall mobilities of 1–4 cm2V-1s-1and hole concentrations of 1017–1018cm-3. The physical and chemical structures of SnO films were characterized by X-ray diffraction analysis and X-ray photoemission spectroscopy. It is concluded that amorphous and SnO-dominant films were obtained as deposited. Further annealing at ≤300 °C induces crystallization but no major chemical reaction. The transmission line method was adopted to characterize the contact resistance between SnO layers and various metal electrodes. Results show that Mo and Ni could be used as effective electrodes for p-type SnO, avoiding the use of noble metals. Finally, p-type SnO TFTs using practical metal electrodes were fabricated, where a field-effect mobility of up to 1.8 cm2V-1s-1and an on/off current ratio of >103were achieved.
Radio Frequency Characteristics of Printed Meander Inductors and Interdigital Capacitors
Authors: Myllymaki Sami , Teirikangas Merja , Nelo Mikko , Tulppo Joel , Sobociński Maciej , Juuti Jari , Jantunen Heli , Sloma Marcin , Jakubowska Malgorzata
Published: May 2013

Radio frequency (RF) characterizations of printed silver ink inductors manufactured at low (150 °C) and high (850 °C) temperatures and interdigital capacitors manufactured at high (850 °C) temperatures were carried out in the 500 MHz to 6 GHz range. The S-parameter responses of the components were measured with a probe station and an Agilent 8510C network analyzer. Electrical parameters such as inductance, capacitance, and a quality factor were estimated from experimental results and numerical calculation. Component parameters are dependent on physical dimensions and material properties. The components were created in a 4 ×4 mm2 area with line widths/gaps of 500/500, 250/250, and 200/200 µm. Windings in the coils varied from 2 to 5 turns and finger counts in the capacitors, from 5 to 11 within the defined area and line widths. As a result, low-T-cured (150 °C) silver ink meander line inductors achieved 8 to 18 nH inductances at 1 and 2 GHz with a quality value of 10–25. High-T-cured (850 °C) silver ink meander line inductors had 6–15 nH inductances and quality values were around 100, indicating a conductivity challenge with low-T-cured inks. Interdigital capacitors with 1 to 4 pF capacitances and sufficient quality values were created. A low-loss BaTiO3 coating was printed over the interdigital capacitors; they exhibited suitable electrical characteristics to allow decreasing the physical size of the component.
Organic-Crystal Field-Effect Transistors Based on Terminal-Substituted Sexithiophenes
Authors: Fukaya Yoshihide , Inoue Atsushi , Fukunishi Yuya , Hotta Shu , Yamao Takeshi
Published: May 2013

We have improved a vapor-phase crystal growth method. The method is characterized by a low-rate molecular gas flow under a quasi-equilibrium condition. The obtained crystals can be applicable to basic and applied research on organic devices. Using the present method, we grew crystals of terminal-substituted α-sexithiophene (6T) derivatives. These have phenyl substituent groups (P6T) or methyl substituent groups (M6T) at both molecular terminals. We made field-effect transistors using these crystals. Their maximum hole mobilities were more than 0.1 cm2·V-1·s-1. Of these devices, the P6T device showed light emissions under applied alternating-current gate voltages. The emissions became rapidly intense with increasing gate voltage amplitude.
Investigation of Hole Transporting Properties in Thin-Film and Single-Crystal Organic Field-Effect Transistor Based on Dinaphtho[2,1-b:1',2'-d]thiophene
Authors: Nakahara Katsumasa , Mitsui Chikahiko , Okamoto Toshihiro , Yamagishi Masakazu , Soeda Junshi , Miwa Kazumoto , Sato Hiroyasu , Yamano Akihito , Uemura Takafumi , Takeya Jun
Published: May 2013

We describe physicochemical properties, crystal structures, and field-effect transistor performances of dinaphtho[2,1-b:1',2'-d]thiophene (DNT-U) with a unique twisted structure. The HOMO energy level of DNT-U was estimated to be -5.77 eV by measurement of electrochemical property in solution, indicating that this material is a promising candidate for air-stable p-type organic semiconductors. DNT-U possesses anisotropic one-dimensional transfer integrals originating from the columnar face-to-face π-stacking motif, which was determined by X-ray single crystal structural analysis. In order to evaluate intrinsic hole transporting ability of DNT-U, we fabricated the single-crystal field-effect transistors (FETs). The devices showed hole mobility of up to 0.15 cm2 V-1 s-1, which value is almost one order of magnitude higher than that of the vacuum deposited thin film FETs.
High-Mobility Organic Thin-Film Transistors Over 10 cm2 V-1 s-1 Fabricated Using Bis(benzothieno)naphthalene Polycrystalline Films
Authors: Kurihara Naoki , Yao Atsushi , Sunagawa Misa , Ikeda Yoichi , Terai Kota , Kondo Hirofumi , Saito Masatoshi , Ikeda Hidetsugu , Nakamura Hiroaki
Published: May 2013

We have synthesized novel thieno-fused compounds, bis(benzothieno)naphthalenes (BBTNs), and studied their thin-film transistors characteristics and thin-film properties. It was found that BBTN derivatives showed high mobilities (up to 15.6 cm2 V-1 s-1). In order to elucidate the origin of high mobilities of BBTNs, X-ray single-crystal structure analysis, XRD measurements, and thermal measurements were carried out. The results suggest that both the herringbone crystal packing and strong CH–π interaction between the thieno-fused cores are the important factors for high mobilities.
Light-Exposure Effects on Electrical Characteristics of 6,13-Bis(triisopropylsilylethynyl)Pentacene/CdTe Composite Thin-Film Transistors
Authors: Park Jaehoon , Kim Dong Wook , Lee Bong Kuk , Jeong Ye-Sul , Petty Michael , Choi Jong Sun , Do Lee-Mi
Published: May 2013

We report the light-exposure effects on solution-processed organic thin-film transistors (TFTs) based on a 6,13-bis(triisopropylsilylethynyl)pentacene (TIPS-pentacene) semiconductor. Under light exposure, the increase in drain current and the positive shift of threshold voltage are observed, which are more remarkable for the TIPS-pentacene/cadmium telluride composite TFT. Herein the photosensitivity in these TFTs is explained in terms of photovoltaic and photoconductive effects. Composite semiconductors blended with sensitizers are suggested to enhance the quantum efficiency of organic phototransistors.
Raman Temperature Measurements of Copper Phthalocyanine Layer of Organic Light-Emitting Diode Using Bandwidth–Temperature Relationship
Authors: Iwasaki Ryota , Hirose Masaki , Furukawa Yukio
Published: May 2013

We have estimated the temperature of a buried copper phthalocyanine (CuPc) layer in an organic light-emitting diode with the glass/indium–tin-oxide (ITO)/CuPc/N,N '-di-1-naphthaleyl-N,N '-diphenyl-1,1'-biphenyl-4,4'-diamine (NPD)/tris(8-quinolinolato)aluminum(III) (Alq3)/LiF–Al structure from the full width at half-maximum (FWHM) of a Raman band at around 1528 cm-1. The FWHMs of the band were measured at temperatures in the range from 25 to 200 °C. A linear equation was obtained from the observed data by the least-squares method. We estimated the temperature of the CuPc layer in an operating organic light-emitting diode at current densities from 100 to 1000 mA/cm2 using this relationship. The highest temperature was 148 ±4 °C at a current density of 1000 mA/cm2.
High-Color-Quality Blue Top-Emitting Organic Light-Emitting Diodes with Enhanced Contrast Ratio
Authors: Zhang Mingxiao , Chen Zhijian , Xiao Lixin , Qu Bo , Gong Qihuang
Published: May 2013

On the basis of a Ag:MoO3 anode, we fabricated blue top-emitting organic light-emitting diodes with enhanced contrast ratio. After doping with MoO3, the reflectivity of Ag anode was reduced by a great ratio. Owing to the decrease in the anode reflectivity, the total reflectivity of the devices also decreased. Accordingly, the contrast ratio of the devices was enhanced. In addition, a purer blue emission was obtained from devices with a low-reflectivity anode. We obtained a blue emission with a spectra peak at 436 nm from top-emitting devices based on 4,4'-bis(2,2'-diphenylvinyl)-1,1'-biphenyl (DPVBi). The emission spectra of the top-emitting devices with a Ag:MoO3 anode were very stable at different view angles.
Reaction Mechanism and Improved Performance of Solution-Based Electrochemiluminescence Cell Driven by Alternating Current
Authors: Nobeshima Taiki , Nakamura Kazuki , Kobayashi Norihisa
Published: May 2013

An AC-driven light-emitting cell based on the electrochemiluminescence (ECL) of tris(2,2'-bipyridyl)ruthenium(II) [Ru(bpy)3
2+] was fabricated by simply placing the electrolyte solution between transparent electrodes, and this AC-driven ECL cell was demonstrated for comparison to a DC-ECL cell. The properties of the ECL cell were dramatically improved by using the AC method. The AC-ECL cell showed the luminance of 56.4 cd/m2, the current efficiency of 0.78 cd/A and the turn-on response time of ca. 15 ms under application of 4 V, 50 Hz AC. We also elucidated the detailed mechanisms of the AC-ECL reaction to monitor the faradaic current. These improved properties and the frequency dependence of the AC-ECL cell were discussed in the relation to the revealed mechanisms.
Fabrication of a Quartz-Crystal-Microbalance/Optical-Waveguide Hybrid Sensor and In situ Evaluation of Vacuum-Evaporated Lead Phthalocyanine Thin Film
Authors: Shinbo Kazunari , Uno Akihiro , Hirakawa Ryo , Baba Akira , Ohdaira Yasuo , Kato Keizo , Kaneko Futao
Published: May 2013

In this study, we fabricated a novel quartz-crystal-microbalance (QCM)/optical-waveguide hybrid sensor. An in situ observation of a lead phthalocyanine (PbPc) thin-film deposition was conducted during vacuum evaporation, and the effectiveness of the sensor was demonstrated. The film thickness was obtained from the QCM frequency, and the optical absorption of the film was observed by optical waveguide spectroscopy using part of the QCM substrate without the electrode. The film absorption depends on the polarization direction, substrate temperature and deposition rate, owing to aggregate formation. The thickness dependence of the absorption property was also investigated.
Solution-Processed Organic Thin-Film Transistor Array for Active-Matrix Organic Light-Emitting Diode
Authors: Harada Chihiro , Hata Takuya , Chuman Takashi , Ishizuka Shinichi , Yoshizawa Atsushi
Published: May 2013

We developed a 3-in. organic thin-film transistor (OTFT) array with an ink-jetted organic semiconductor. All layers except electrodes were fabricated by solution processes. The OTFT performed well without hysteresis, and the field-effect mobility in the saturation region was 0.45 cm2 V-1 s-1, the threshold voltage was 3.3 V, and the on/off current ratio was more than 106. We demonstrated a 3-in. active-matrix organic light-emitting diode (AMOLED) display driven by the OTFT array. The display could provide clear moving images. The peak luminance of the display was 170 cd/m2.
Large-Area Organosilicon Film Deposition Using Cyclonic Atmospheric Pressure Glow Discharge
Authors: Lin Jin-He , Tsai Ching-Yuan , Liu Wei-Ting , Syu Yu-Kai , Huang Chun
Published: May 2013

Cyclonic atmospheric pressure plasma is developed for chamberless deposition of organosilicon thin films from argon/hexamethyldisoxane (HMDSO) mixtures. The surface properties of the resulting plasma films were investigated as a function of RF plasma power. Film characterization was performed by static contact angle measurement, scanning electron microscopy (SEM), atomic forced microscopy (AFM), and X-ray photoelectron spectroscopy (XPS). It was found the RF plasma power is the key factor that to affects the film growth in the atmospheric pressure plasma chemical vapor deposition process. SEM and AFM results indicated that a smooth, continuous, and uniform surface of organosilicon thin films can be formed at a relatively low plasma power input. XPS indicated that atmospheric-pressure plasma-deposited organosilicon films present mainly inorganic characteristics. This study shows a potential of chamberless film growth at atmospheric pressure to form organosilicon thin films for large-area deposition.
Plasma Characteristics of Inductively Coupled Plasma Using Dual-Frequency Antennas
Authors: Kim Tae Hyung , Kim Kyong Nam , Mishra Anurag Kumar , Seo Jin Seok , Jeong Ho Boem , Bae Jung Oun , Yeom Geun Young
Published: May 2013

The plasma characteristics of inductively coupled plasma (ICP) sources operated with dual-frequency antennas with frequencies of 2 and 13.56 MHz were investigated and compared with a source operated with a single-frequency antenna at 13.56 MHz. Improved plasma characteristics such as higher plasma density, lower plasma potential, and lower electron temperature were observed with the dual-frequency ICP source owing to the high absorbed power through the lower driving of the frequency antenna. Also, the variation of the dual-frequency power ratios changed the electron energy distribution. Therefore, when silicon was etched using the dual-frequency ICP with CF4/Ar, the maximum etching selectivity of silicon over the photoresist could be observed at a 2 MHz rf power ratio of approximately 70% possibly due to the different gas dissociation characteristics for different dual-frequency power ratios, even though the etching rate of silicon increased with the 2 MHz power ratio owing to the increased plasma density. In addition, by using the dual-frequency ICP antennas instead of the single-frequency antenna, the plasma uniformity was also improved.
Study of Low Pressure Inductively Coupled Plasmas: Effects of the DC Bias and Gas Flow Rate
Authors: Tong Lizhu
Published: May 2013

Low pressure inductively coupled Ar/N2plasmas operating at the rf frequency of 13.56 MHz and the total gas pressure of 20 mTorr are studied in this paper. The plasma simulation is fully coupled with fluid dynamics. The gas temperature is 300 K and the input power is 300 W. 95% Ar/5% N2gas mixtures are considered. The dc bias is impressed on the substrate electrode from -20 to -100 V at the gas flow rate from 20 to 1000 sccm. It is found that the electron density increases and electron temperature in the bulk decreases when the gas flow rate increases, especially for the gas flow rate of more than 100 sccm. The electron temperature shows a large variation with the dc bias. At low dc bias, the area with high electron temperature is located within the region below the coil domain, whereas at high dc bias, the area with high electron temperature appears in the neighborhood of the substrate electrode, where the critical value is found around -50 V. The present work provides an estimation of the energies of ions arriving at the substrate and the effect of gas flows is investigated.
Surface Treatment and Characterization of Indium–Tin-Oxide Thin Films Modified Using Cyclonic Atmospheric-Pressure Plasma
Authors: Tsai Ching-Yuan , Huang Chun
Published: May 2013

The surface characteristics of indium–tin-oxide (ITO) films modified using cyclonic atmospheric-pressure plasma were investigated by static contact angle (CA) analysis as well as atomic force microscopy (AFM). The surface modification effects of plasma operational conditions including treatment time, plasma power, gas flow rate, and distance of nozzle to the substrate on the ITO surface features were examined. Cyclonic atmospheric pressure plasma-modified ITO films showed a significant decrease in static water contact angle. The surface energy calculated by the Owens–Wendt method primarily increased from the polar component after cyclonic atmospheric pressure plasma treatment. The glow feature and luminous plasma species in the cyclonic atmospheric pressure plasma were identified by optical emission spectroscopy (OES). Atomic force microscopy revealed that the cyclonic atmospheric pressure plasma-modified ITO surface showed a slightly increased surface roughness and a similar morphology to the untreated ITO surface. As a result, it is believed that this cyclonic atmospheric pressure plasma alters the ITO surface physicochemical features, which can in turn improve ITO films performance for various applications.
Gas Cluster Ion Beam Etching under Acetic Acid Vapor for Etch-Resistant Material
Authors: Yamaguchi Akira , Hinoura Ryo , Toyoda Noriaki , Hara Ken-ichi , Yamada Isao
Published: May 2013

Gas cluster ion beam (GCIB) etching of etch-resistant materials under acetic acid vapor was studied for development of new manufacturing process of future nonvolatile memory. Etching depths of various etch-resistant materials (Pt, Ru, Ta, CoFe) with acetic acid vapor during O2-GCIB irradiations were 1.8–10.7 times higher than those without acetic acid. Also, etching depths of Ru, Ta, CoFe by Ar-GCIB with acetic acid vapor were 2.2–16.1 times higher than those without acetic acid. Even after etching of Pt, smoothing of Pt was realized using O2-GCIB under acetic acid. From XPS and angular distribution of sputtered Pt, it was shown that PtO
x
layer was formed on Pt after O2-GCIB irradiation. PtO
x
reacted with acetic acid by GCIB bombardments; as a result, increase of etching depth was observed.