bluuebunny/crossref_metadata_2025_split huggingface dataset:
Control of Trenching and Surface Roughness in Deep Reactive Ion Etched 4H and 6H SiC
Authors: Beheim Glenn M. , Evans Laura J. 
Published: April 2011

AbstractAn optimized deep reactive ion etching (DRIE) process for the fabrication of SiC microstructures has been developed. The optimized process enables the etching of 4H and 6H SiC to depths > 100 microns with the required characteristics of (1) high rate (>0.5 microns/min), (2) vertical sidewalls, (3) minimal microtrenching at the sidewall base, and (4) smooth etched surfaces. The optimized process was determined based on the results of an experiment (full factorial design) which determined how the etch characteristics are affected by four important process parameters: temperature of the wafer chuck, pressure within the chamber, and concentrations of O2 and Ar in a gas flow comprised of O2, Ar and SF6. This study is believed to be the first systematic investigation of the effect of temperature on SiC DRIE characteristics; substrate heating was found to be a key in producing the desired etch properties.
1.8 kV, 10 mOhm-cm2 4H-SiC JFETs
Authors: Scofield James D. , Ryu Sei-Hyung , Krishnaswami Sumi , Fatima Husna , Agarwal Anant 
Published: April 2011

AbstractFabrication and characteristics of high voltage, normally-on JFETs in 4H-SiC are presented. The devices were built on 5x1015 cm-3 doped, 12 μm thick n-type epilayer grown on a n+ 4H-SiC substrate. A specific on-resistance of 10 m Ω-cm2 and a blocking voltage of 1.8 kV were measured. Device characteristics were measured for temperatures up to 300oC. An increase of specific on-resistance by a factor of 5 and a decrease in transconductance were observed at 300oC, when compared to the value at room temperature. This is due to a decrease in bulk electron mobility at elevated temperature. A slight negative shift in pinch-off voltage was also observed at 300oC. The devices demonstrated robust DC characteristics for temperatures up to 300oC, and stable high temperature inverter operation in a power DC-DC converter application, using these devices, is reported in this paper.
Vertical MOSFET Devices Fabricated on 3C-SiC with High and Low Material Quality
Authors: Schoner Adolf , Bakowski Mietek , Ericsson Per , Stromberg Helena , Nagasawa Hiroyuki , Abe Masayuki 
Published: April 2011

AbstractVertical DMOSFET devices with sizes from single cell to 3x3 mm2 large devices have been fabricated on cubic 3C-SiC material. The used 3C-SiC substrates had varying material quality. The best quality had a more than 2 orders of magnitude lower density of extended crystal defects than the worst material. The processed and investigated vertical DMOSFET devices were designed for 600 V blocking voltage and had hexagonal unit cells with 2 μm channel length and aluminum implanted termination rings. The p-body was aluminum implanted and the source was phosphorus implanted. As deposited Ti/W contacts were evaluated as source and drain metallization. Single cell vertical DMOSFET devices, processed on the low defect density material quality, gave voltage blocking capabilities of more than 600 V with leakage currents of 0.1 to 10 μA. The same devices could handle currents around 5 mA in on-state at 15 V gate bias. MOSFET devices with 50 to 100 unit cells had blocking voltages of 400 to 500 V with on-state currents of 0.2 to 0.4 A at 15 V gate bias, indicating the potential of 3C-SiC for the fabrication of next generation power MOSFET devices.
Synthesis and Measurement of Magnetic Cobalt DNA-Templated Nanowire
Authors: Lin Chia-Hsin , Tong Shi-Yuan , Lin Shin-Wei , Chen Hsin-Lung , Liu Yi-Chun , Lin Hsien-Kuang , Liu Wen-Lian , Cheng Syh-Yuh , Wang Yi-Hui 
Published: April 2011

AbstractBiomaterials such as DNA are currently being explored as potential application in nanotechnology. DNA templates were immobilized on crystal-violet-treated mica by spin coating as a grid-like network. The DNA templates were then activated with PdCl2, followed by reduction with dimethylamine borane (DMAB) to form seeding nanoclusters on the DNA chain. Afterward the DNA chain with deposition of zero-valence Pd nanoclusters was grew in a Co electroless plating bath. SEM/EDS analysis revealed that Co nanoparticles could be assembled on the DNA template to form magnetic nanowires with a diameter of 25nm to 250nm by a conventional electroless plating. Vibrating Sample Magnetometer analysis indicated that Co-DNA nanowires showed a paramagnetic characteristic. Grid-like networks of DNA template were effectively preserved after Co electroless plating. These characteristics indicated that DNA is an ideal template for the production of magnetic nanowires, which could be useful in the development of high-density memory storage or magnetic field sensors.
Biodegradable Nano-Material Composites for Use in an Inkjet Printing System
Authors: Levi Nicole H , McGuirt John B. , Coldren Faith M. , Carroll David L. 
Published: April 2011

AbstractBiomaterials for development of resorbable, three-dimensional tissue scaffolds have been used in a modified thermal inkjet printing system to explore compatibility of materials, solvents and the printing system. The polymers included collagen (type I), sodium alginate, fibronectin, poly-lactic co-glycolic acid (PLGA), polyethylene glycol (PEG), and tetraglycol were tested. Single-walled carbon nanotubes were combined with the biopolymers to determine which systems in which they would blend well, and be able to print. Uncovering which biopolymers may be printed together offers insight into development of materials which most closely match the properties of biological tissue.
Evidence for a Structural Transition to a Superprotonic CsH2PO4 Phase Under High Pressure
Authors: Botez Cristian E. , Chianelli Russell R. , Zhang Jianzhong , Qian Jiang , Zhao Yusheng , Majzlan Juraj , Pantea Cristian 
Published: April 2011

ABSTRACTWe have used synchrotron X-ray powder diffraction (SXRPD) to investigate the structural behavior of cesium dihydrogen phosphate upon heating. Temperature-resolved data collected at ambient-pressure demonstrate that a transition from the room-temperature monoclinic phase (P21/m; a=7.90Å, b=6.39Å, c=4.87Å, and β=107.64°) to a high-temperature cubic phase (Pm3m; a=4.96Å) occurs at T=237°C. The high-temperature phase is not stable under ambient-pressure conditions, even in the absence of further heating. On the other hand, SXRPD measurements carried out under high-pressure (∼1GPa) evidence a transition from monoclinic to a stable cubic phase (Pm3m, a=4.88Å) at a temperature within the 255°C-275°C range. A 1000-fold increase in the proton conductivity (indicating the transition to the superprotonic phase) was previously observed under the same non-ambient conditions. Therefore, our results represent strong evidence that the superprotonic behavior in cesium dihydrogen phosphate is associated with a monoclinic-to-cubic polymorphic structural transition and not with chemical modifications.
Surface Characterization of Silicon Carbide Following Shallow Implantation of Platinum Ions for High Temperature Hydrogen Sensing Applications
Authors: Muntele Claudiu , Budak Satilmis , Muntele Iulia , Ila Daryush 
Published: April 2011

ABSTRACTSilicon carbide is a promising wide-bandgap semiconductor intended for use in fabrication of high temperature, high power, and fast switching microelectronics components running without cooling. For hydrogen sensing applications, silicon carbide is generally used in conjunction with either palladium or platinum, both of them being good catalysts for hydrogen. Here we are reporting on the temperature-dependent depth profile modifications of tungsten electrical contacts deposited on silicon carbide substrates.
Differentiation of Bone Marrow Stem Cells on Inkjet Printed Silk Lines
Authors: Limem Skander , Calvert Paul , Kim Hyeon Joo , Kaplan David L. 
Published: April 2011

ABSTRACTWater based silk solutions were successfully inkjet printed for the first time into patterns of parallel lines onto vinyl plastic substrates. Human bone marrow stromal cells (hMSCs) were seeded on the silk printed patterns and cultured in the presence of 100 ng/ml of bone morphogenic protein (BMP-2). After one week of culture cell growth and attachment showed site specificity on the silk printed lines. Both alkaline phosphatase activity and cell morphology indicated hBMSCs differentiation into osteogenic cells along the silk printed lines. After 4 week of culture, the cellular bridging of adjacent silk printed lines took place for all interline distances lower than 1.25 mm. Therefore, commercial inkjet printing technology can produce complex viable cellular patterns with 111 ± 24 μm lateral resolution, through the deposition of bioactive materials. The results provide a first step toward cell specific control using 3D inkjet printing techniques using biocompatible gel systems to regulate cell functions.
Ceramic/Polymer Nanocomposite Tissue Engineering Scaffolds for More Effective Orthopedic Applications: From 2D Surfaces to Novel 3D Architectures
Authors: Liu Huinan , Webster Thomas J. 
Published: April 2011

ABSTRACTCeramic/polymer nanocomposites simulate bone much closer in terms of its nanostructure and associated properties, thus, offering a promising opportunity for bone regeneration in a natural way. Previous studies demonstrated improved osteoblast (bone-forming cell) adhesion and long-term functions (such as alkaline phosphatase activity and calcium-containing mineral deposition) on nanometer scale surface roughness provided by well-dispersed titania nanoparticles in poly-lactide-co-glycolide (PLGA). For example, the nanocomposites with the closest surface roughness to natural bone at the nano-scale promoted the most bone cell adhesion and calcium deposition. The current studies focus on further mimicking bone by building three-dimensional structures from titania/PLGA nanocomposites using a novel aerosol based 3D printing technique (one type of rapid prototyping technique, because, similarly, natural bone assembles its three-dimensional hierarchical architecture from nanostructured building blocks). Using this technique, bone fracture data acquired by computed tomography (CT) can be transferred into CAD models and used to direct the fabrication of versatile bone substitutes. Field emission scanning electron microscopy (FESEM) was used to characterize the structure and surface features of these 3D scaffolds. The results demonstrated that 3D printed nano-scaffolds had a well-controlled, repeatable inner structure and, moreover, possessed uniformly dispersed titania nanoparticles which provided for nano-scale surface features throughout the PLGA matrix. Osteoblast adhesion tests were conducted on the 3D titania/PLGA nanocomposite scaffolds created by this technique and the results demonstrated that these 3D scaffolds further promoted osteoblast infiltration into porous structures compared to previous nanostructured surfaces. In conclusion, results of this study have evaluated a promising new orthopedic nanocomposite and a means of fabricating a hierarchical macro-structure from such nanomaterials that can mimic properties of natural bone, thus, providing a new material and approach for more effective orthopedic applications.
Study of Polymeric Microneedle Arrays for Drug Delivery
Authors: Ovsianikov Aleksandr , Doraiswamy Anand , Narayan Roger , Chichkov Boris N. 
Published: April 2011

ABSTRACTTwo-photon polymerization (2PP) is a novel technology for the fabrication of complex three-dimensional (3D) microstructures. The number of applications employing this technology is rapidly increasing, and includes the fabrication of three-dimensional photonic crystals [1-4], medical devices, and scaffolds for tissue engineering [5, 6]. We have used 2PP to fabricate microneedle arrays with various geometries. These devices provide a unique approach for transdermal delivery of nucleic acid- and protein-based pharmacologic agents. Many of issues associated with conventional intravenous drug administration, including pain to the patient, trauma at the injection site, and difficulty in providing sustained release of a pharmacological agent, may be eliminated by applying the microneedles. The effect of microneedle geometry (e.g., tip sharpness and aspect ratio) on skin penetration was examined. Our results indicate that microneedles created using 2PP technique are suitable for in vivo use, and integration with next generation MEMS- and NEMS-based drug delivery devices.
Synthesis and Optical Properties of Silicon Oxide Nanowires
Authors: Gelloz Bernard , Coffinier Yannick , Salhi Billel , Koshida Nobuyoshi , Patriarche Gilles , Boukherroub Rabah 
Published: April 2011

ABSTRACTThe paper reports on the synthesis and structural characterization of amorphous silicon oxide nanowires (SiONWs). The nanowires were prepared using the solid-liquid-solid (SLS) technique and display an average mean diameter in the range of 20-150 nm and 15-20 μm in length. Energy dispersive spectrometry (EDS) analysis revealed that the nanowires consist of Si and O elements in a ratio of approximately 1:2. The result was corroborated by the presence of a single peak at around 103 eV in the X-ray photoelectron (XPS) spectrum. As-prepared SiONWs display blue photoluminescence (PL) centered ∼ 400 nm. The blue luminescence is inhomogeneous with an increase in the PL peak intensity by a factor of 1.8 at certain areas of the surface. Next, we have investigated the effect of high-pressure water vapor annealing (HWA) on the PL and found that while the PL became homogeneous, a decrease of its intensity by a factor 2 was observed. The origin of the blue emission could be attributed to defect centers of oxygen deficiency in the wires.
Formation of a Thermally Stable NiSi FUSI Gate Electrode by a Novel Integration Process
Authors: Tan Shiang Yu , Chiu Hsien-Chia , Hu Chun-Yen 
Published: April 2011

ABSTRACTNickel silicide is promising to be the choice material as contact to the source, drain, and gate for sub-65 nm and 45 nm CMOS devices. However, the thermal stability of NiSi is worse as the high resistivity phase of NiSi2 nucleates at about 750 °C and film agglomeration occurs even at a temperature as low as 600 °C. The process integration issues and formation thermally stable NiSi are needed to be understood and addressed. In order to obtain a thermally stable Ni-FUSI gate electrode, we introduced a novel integration process by using a two-step anneal process associating with properly tuned thickness of the initial Ni film and implant BF2atoms during the poly-gate formation. As results, push the transformation of NiSi2to a higher temperatures at about 900 °C. Several measurement techniques such as XRD, TEM, SEM and Resistivity are carried out to demonstrate its physical and electrical properties.
Preparation and Electrical Properties of the MWNT/Polymer Nanocomposite Fibers
Authors: Wang Guan , Tan Zhongkui , Liu Xueqing , Samuilov Vladimir , Dudley Michael 
Published: April 2011

ABSTRACTAn oxidation method has been applied to functionalize multiwalled carbon nanotubes with carboxylic acid (-COOH) group. Functionalized carbon nanotubes (f-MWNT) were used for the fabrication of conducting nanocomposite fibers by electrospinning, in comparison with the composite nanofibers made of un-functionalized carbon nanotubes (u-MWNT). Our results showed that the addition of f-MWNTs into polymer solution could increase the compatibility of MWNTs with the polymer matrix, and thus result in composite nanofibers with uniform diameters. Alignment of the composite nanofibers was achieved by using a rotating drum as the collector. F-MWNTs were found to align parallel to the axis direction of the nanofibers. Temperature-dependent DC electrical properties of a single composite fiber were investigated by a two-probe method. It was shown that the conductivity of the material could be significantly improved above a percolation threshold. The conductivity could be of ten orders of magnitude higher than the pure PVAc.
Perylene Diimide as the Black-Layer Material of the OLEDs
Authors: Lee Jiun-Haw , Chuang Kai-Hsiang , Ho Yu-Hsuan , Lin Chi-Feng , Chao Chun-Chieh , Leung Man-Kit , Li Cheng-Yu , Chen Hsuen-Li 
Published: April 2011

ABSTRACTIn this paper, we use a perylene diimide derivative serving as a destructive and an absorption layer of the “black cathode” of an organic light-emitting device (OLED). A thin and semitransparent metal between the electron transport layer and the perylene diimide is used for better electron injection and also serves as the destructive interference. The thickness of such layer is critical since thinner metal results in lower reflectance, but higher diving voltage due to worse electron injection. To enhance the electron injection capability, the thickness of the thin metal increases which in turns to increase the reflectance. Here, we used a double-metal configuration to decrease the reflectance and maintain the electron injection capability at the same time.
Characterization of Pyrazoline Organic Nanoparticles Encapsulated with Poly(Methyl Methacrylate-co-Ethylene Glycol Dimethacrylate) for Color Electronic Paper
Authors: Kang Hyo Sim , Oh Sun Wha , Kang Young Soo 
Published: April 2011

ABSTRACT1-Phenyl-3-naphthyl-5-((dimethylamino)phenyl)-2-pyrazoline with different diameters of 40 - 190 nm were prepared by the reprecipitation method and polymerized with poly(methyl methacrylate-co-ethylene glycol dimethacrylate) using cationic surfactants for full color electronic paper, which is expected to substitute for the future display. The electronic ink particles of pyrazoline organic nanoparticles polymerized by poly(methylmethacrylate-co-ethylene glycol dimethacrylate) were prepared and monodispersed successfully in aqueous alcohol medium. The size of mono-dispersed electronic ink particles is from 160 to 550 nm. The ink particle size was found to decrease with increasing concentration of the surfactant. The effect of surfactant was significant. The appropriate additions of surfactants result in an increase in electrophoretic mobility. The electrophoretic mobility of the resulting electronic inks was −7.5 to −3.6 × 10−5 cm2/ V·s in the presence of surfactants.
Dendritic Iridium(III)-Encapsulated Complexes for Organic Light Emitting Diodes
Authors: Son Ho-Jin , Han Won-Sik , Choi Kyu-Bum , Kim Dae-Hyun , Ko Jaejung , Noh Seung-Uk , Lee Changhee , Kang Sang Ook 
Published: April 2011

ABSTRACTThe syntxhesis, photo-physics, and electroluminescence of new types of Iridium(III)-encapsulated dendrimers are described. Thus, four different iridium complexes [Ir(III)(C^N)2(LX), Blue-DCBP, Green-DCBP, Yellow-DCBP, and Red-DCBP] with ancillary ligand tethered to the CBP dendritic unit were synthesized and investigated for their photo-physical properties. A large enhancement in electroluminescence performance was observed by using these dendrimers as host/dopant hybrid materials in layered emitting diodes. In particular, host/dopant ratio can be systematically adjusted by varying dendritic generations. These results demonstrate that new Ir(III)-encapsulated dendrimers can be used as potential single-layer materials for organic light emitting diodes. Large difference in the intra-molecular charge transfer phosphorescence quantum yields and electroluminescence effiencies were observed among dendriritic generations.
Availability of Liquid Crystalline Materials for Organic Polycrystalline Semiconductor Thin Films
Authors: Iino Hiroaki , Hanna Jun-ichi 
Published: April 2011

ABSTRACTWe have investigated the charge carrier transport properties of polycrystalline films fabricated with discotic and calamitic liquid crystals. The polycrystalline films of these liquid crystals exhibiting particular textures under a polarized microscope, i.e., hexagonal and co-circular patterns for discotic and calamitic liquid crystals, respectively, which indicate that the molecular alignment in the liquid crystalline phase is well preserved exhibit clear hole transport along with molecular stacks even in a 15 μm thick film, judging from transient photocurrents by time of flight method. The hole mobilities are over 0.1 cm2/Vs at room temperature. These results indicate formation of fewer grain boundaries across conduction channels. On the other hand, the carrier transport properties in the polycrystalline films of non-liquid crystalline molecules with the same molecular shape exhibit no particular patterns as described and photocurrents are annihilated in the bulk as a function of time, indicating many deep trap sites in grain boundaries. The present results indicate that the liquid crystalline molecule is a good candidate for preparing quality organic polycrystalline semiconductor thin films in opto-electronic applications.
Deep-Level Optical Spectroscopy Investigation of Trap Levels in Tris(8-Hydroxyquinoline) Aluminum
Authors: Nakano Yoshitaka , Noda Koji , Fujikawa Hisayoshi , Morikawa Takeshi , Ohwaki Takeshi 
Published: April 2011

ABSTRACTWe have investigated band gap states in tris(8-hydroxyquinoline) aluminum (Alq3) with and without quinacridone (Qd) doping on fabricated indium-tin-oxide (ITO)/Alq3(:Qd)/LiF/Al devices by using a deep-level optical spectroscopy (DLOS) technique. Non-doped Alq3 sample shows a discrete trap level located at ∼1.39 eV below the lowest unoccupied molecular orbital band in addition to near-band-edge transitions at 2.2 - 3.6 eV. The pronounced 1.39 eV level is attributable to an intrinsic nature of Alq3 and can be active as an efficient generation-recombination (GR) center that may impact the photophysical properties. On the other hand, Qd-doped Alq3 sample exhibits a new deep level at ∼2.40 eV with increasing the double carrier injection rate, corresponding to the highest occupied molecular orbital band of the Qd. Simultaneously, this GR center is subject to charge up positively due to the presence of holes injected into the Qd doping level for Qd-doped Alq3.
Laser Thermoreflectance Measurement for Evaluating Heat Capacity and Interface Heat Resistance of Low-k Films
Authors: Ye Jiping , Okamura Takeo , Sato Shigeo 
Published: April 2011

ABSTRACTA novel technique that combines laser thermoreflectance measurement with the 3-omega method is proposed for evaluating the heat capacity of low-k films and the heat resistance at the interface between the low-k film and Si substrate. It was demonstrated that the heat capacity of thin films and the heat resistance at the interface can be determined by obtaining the heat effusivity of the film from laser thermoreflectance measurements, the total heat resistance obtained with the 3-omerga method, and the film density and thickness found from x-ray reflectivity measurements. The heat capacity of SiOC films was determined to be Cp(SiOC) =1.1 kJ/kgK with interface heat resistance of Rint(SiOC) = -2.37×10−8 m2k/W, while the heat capacity of Th-ox films was determined to be Cp(Th−ox) =0.61 kJ/kgK with Rint(Th−ox) = +1.74×10−8 m2k/W. A DSC heat capacity measurement confirmed the reliability of the evaluated Cp data. XRR and TEM examinations revealed that the negative interface heat resistance exhibited by the SiOC films originated from a high density layer at the interface between the film and Si substrate; and the positive interface heat resistance displayed by the Th-ox films stemmed from atomic defects at the interface between the film and Si substrate. These results confirmed that this method is a reliable and effective method for evaluating the heat capacity of low-k films and the heat resistance at the interface.