bluuebunny/crossref_metadata_2025 huggingface dataset:
Study of Protein Adsorption onto a Polymer Film by in-situ UV Attenuated Total Reflectance Spectroscopy
Authors: Bratescu Maria-Antoaneta , Fujita Syohei , Saito Nagahiro , Takai Osamu
Published: August 2010

Our work presents results on human plasma protein adsorption onto a polyacrylic acid (PAA) film prepared via surface wave plasma (SWP) induced graft polymerization. The PAA film prepared in this manner is characterized by a carboxyl functional group and a constant contact angle in water of 35°. The adsorption kinetics of human plasma fibrinogen (HPF) and human serum albumin (HSA) proteins were measured by in-situ UV-ATR spectroscopy. The free energy of adsorption on PAA treated as well as untreated surfaces was −28 kJ M−1 and −22 kJ M−1 for HPF and HSA, respectively, regardless of surface chemistry. We determined that 14 μM and 6 μM HPF concentrations are enough to cover half of the maximum possible of surface coverage on silica and PAA film, respectively. HSA protein concentrations of 154 μM and 118 μM are enough to cover half of the maximum accessible surface of silica and PAA film, respectively. For surface treatment of implants with PAA polymer and protein, the necessary protein concentration for effective surface coverage should be known.
Advanced Functional Graphite-Coated Magnetic Nanoparticles as RF Thermal Ablation Agents for Cancer Therapies
Authors: Xu Yang , Mahmood Meena Waleed , Li Zhongrui , Dervishi Enkeleda , Trigwell Steve , Zharov Vladimir P. , Ali Nawab , Saini Viney , Biris Alexandru R. , Lupu Dan , Biris Alexandru S.
Published: August 2010

Graphitic shells coated ferromagnetic cobalt nanoparticles (C-Co-NPs) with diameters of around 7-9 nm cubic crystalline structures were synthesized by catalytic chemical vapor deposition (CCVD). X-ray diffraction (XRD) and X-ray photoelectron spectroscopy (XPS) analysis indicated that the Co-NPs inside the carbon shells were preserved in the metallic state. Confocal microscope images revealed effective penetrations of C-Co-NPs through plasmatic membranes into the nucleus of the cultured HeLa cancerous cells. Low RF radiation of 350 kHz triggered the cell death, process that was found to be dependent on the NPs concentration and application time. Compared to carbon nanostructures such as single wall carbon nanotubes, super paramagnetic cobalt nanoparticles demonstrated higher specificity for RF absorption and heating. This work indicates a great potential of a new technology for tumor thermal ablation.
In vivoMonitoring of Gold Nanorods and Tissue Damage Mediated with Their Photothermal Effect
Authors: Niidome Takuro , Akiyama Yasuyuki , Shimoda Kohei , Kawano Takahito , Mori Takeshi , Katayama Yoshiki , Niidome Yasuro
Published: August 2010

Gold nanorods have a strong surface plasmon band at the near infrared region. The absorbed light energy is then converted to heat. Since near infrared light can penetrate deeply into tissue, gold nanorods are expected to be used as a contrast agent for bioimaging using the near infrared light and photosensitizers for photothermal therapy. The surface plasmon bands of intravenously injected the gold nanorods were directly monitored from the mouse abdomen by using a spectrophotometer equipped with an integrating sphere. The absorbance at 900 nm from PEG5,000-modified gold nanorods immediately increased after injection and reached a plateau. The injection of phosphatidylcholine-modified gold nanorods also increased the absorbance at 900 nm, but the absorbance decreased single exponentially with a 1.3-min half-life. To demonstrate photothermal tumor therapy, the PEG-modified gold nanorods were directly injected into subcutaneous tumors in mice, then, near infrared laser light was irradiated to the tumor. After the treatment, significant suppression of tumor growth was observed.
A Self-assembled, Drug-deliverable Nanomaterial for Cartilage Tissue Engineering
Authors: Chen Yupeng , Fenniri Hicham , Webster Thomas J.
Published: August 2010

The current clinical treatment of cartilage defects involves autologous chondrocyte implantation into cartilage defect sites. However, one of the complications associated with this method is the lack of bonding between the implanted materials and natural tissue. Helical rosette nanotubes (HRNs) are novel biomimetic self-assembled supramolecular structures whose basic building blocks are DNA base-pairs. HRNs are similar in size to collagen in cartilage. Moreover, previous studies have shown that HRNs are biocompatible and increase the adhesion of numerous cells compared to other commonly used cartilage implant materials (like hydrogels and Ti). In addition, HRNs can solidify into a viscous gel at body temperatures under short periods of time. Thus, it is hoped that HRNs can serve as a novel in situ tissue implant to improve cartilage cell adhesion and functions. In this study, in order to heal cartilage rupture and regenerate cartilage during possible implantation, the mechanical properties of select hydrogel/HRN composites were tested. In addition, electro-spinning was used to generate three-dimensional, implantable, composite fibers encapsulated with chondrocytes and fibroblast-like type-B synoviocytes (SFB cells, a type of mesenchymal stem cell). Importantly, results showed that drug-delivered HRNs enhanced hydrogel adhesive strength and created a scaffold with nanometer-rough surface structures pertinent for cartilage regeneration. In this manner, this study provided an alternative cartilage regenerative material which relies on nanotechnology that can be injected as a liquid, solidify at body temperatures under short periods of time, have suitable mechanical properties to collagen, and promote cell functions.
Decomposition of Mixed Phase Silicon Raman Spectra
Authors: Ledinský Martin , Stuchlík Jiri , Vetushka Aliaksei , Fejfar Antonin , Kočka Jan
Published: August 2010

Series of Raman spectra were measured for microcrystalline silicon thin film with variable crystallinity. Five sets of Raman spectra (corresponding to excitations at 325 nm, 442 nm, 514.5 nm, 632.8 nm and 785 nm wavelengths) were subjected to factor analysis which showed that each set of spectra consisted of just two independent spectral components. Decomposition of the measured Raman spectra into the amorphous and the microcrystalline components is illustrated for 514.5 nm and 632.8 nm excitations. Effect of the light scattering on absolute intensity of Raman spectra was identified even for excitation wavelength highly absorbed in the mixed phase silicon layers.
High Efficiency Large Area a-Si:H and a-SiGe:H Multi-junction Solar Cells Using MVHF at High Deposition Rate
Authors: Xu Xixiang , Beglau Dave , Ehlert Scott , Li Yang , Su Tining , Yue Guozhen , Yan Baojie , Lord Ken , Banerjee Arindam , Yang Jeff , Guha Subhendu , Hugger Peter G. , Cohen David J.
Published: August 2010

We have developed high efficiency large area a-Si:H and a-SiGe:H multi-junction solar cells using a Modified Very High Frequency (MVHF) glow discharge process. We conducted a comparative study for different cell structures, and compared the initial and stable performance and light-induced degradation of solar cells made using MVHF and RF techniques. Besides high efficiency, the MVHF cells also demonstrate superior light stability, showing <10% degradation after 1000 hour of one-sun light soaking at 50 °C. We also studied light-induced defect level and hydrogen evolution characteristics of MVHF deposited a-SiGe:H films and compared them with the RF deposited films.
Study of Solid/liquid Interfaces in Organic Field-effect Transistors with Ionic Liquids
Authors: Ono Shimpei , Miwa Kazumoto , Seki Shiro , Takeya Jun
Published: August 2010

We report high-mobility rubrene single-crystal field-effect transistors with ionic-liquid electrolytes used for gate dielectric layers. As the result of fast ionic diffusion to form electric double layers, their capacitances remain more than 1.0 μF/cm2 even at 0.1 MHz. With high carrier mobility of 9.5 cm2/Vs in the rubrene crystal, pronounced current amplification is achieved at the gate voltage of only 0.2 V, which is two orders of magnitude smaller than that necessary for organic thin-film transistors with dielectric gate insulators. The results demonstrate that the ionic-liquid/organic semiconductor interfaces are suited to realize low-power and fast-switching field-effect transistors without sacrificing carrier mobility in forming the solid/liquid interfaces.
Modification of Semiconductor-Dielectric Interface in Organic Light-emitting Field-effect Transistors
Authors: Wang Yan , Kumashiro Ryotaro , Komatsu Naoya , Tanigaki Katsumi
Published: August 2010

In this work, ambipolar rubrene single crystal field-effect transistors (FETs) with PMMA modification layer and Au/Ca as electrodes were fabricated. The electron mobility was studied in these devices. PMMA modification layer on the surface of SiO2 is necessary for electron behavior. We found that the device with PMMA modified insulator and Au-Ca asymmetric metals possessed hole mobility and electron mobility of 1.27 and 0.017 cm−2/Vs, respectively. Furthermore, the shift of light emitting with applied gate voltage was observed in this device.
Optimization of low-k UV Curing: Effect of Wavelength on Critical Properties of the Dielectrics
Authors: Aksenov German , De Roest David , Verdonck Patrick , Marsik Premysl , Shamiryan Denis , Baklanov Mikhail R
Published: August 2010

The results of recent investigations show that after UV curing of CVD SiCOH low-k films deposited with organic material (porogen) some amount of the porogen remains in the cured films in the form of non-volatile graphitized phase, known as “porogen residue”. These residues could influence leakage current and reliability. The goal of the present work is investigation of the different parameters of UV curing that can influence amount of the porogen residue. In this work we focused generally on the study of the amount of porogen residues as function of the wavelength of curing light and the porosity of the material (amount of deposited porogen). To study the curing dependence on the wavelength, we compared optical properties (measured by spectroscopic ellipsometry) and IR adsorption (measured by FTIR) of samples cured by 172 nm monochromatic light (lamp A) with samples cured by broadband source with wavelength more than 200 nm (lamp B). To understand how the amount of porogen residue depends on the amount of deposited porogen (porosity), three films with different k-value were deposited: a film with k = 3 deposited without porogen and two porogen-based low-k with target k-value of 2.5 and 2.3. Furthermore, taking into account that He/H2 plasma effectively removes the porogen residues from porous films without any plasma damage of the matrix material, we exposed the films to that plasma. Then these films were cured by broadband lamp at different temperatures and amount of porogen residues was measured by ellipsometry. It was found that He/H2 plasma cannot fully remove the porogen and causes film shrinkage. The Subsequent UV curing does not produce significant changes.
Large-Scale Electromigration Statistics for Cu Interconnects
Authors: Hauschildt Meike , Gall Martin , Hernandez Richard
Published: August 2010

Even after the successful introduction of Cu-based metallization, the electromigration failure risk has remained one of the important reliability concerns for advanced process technologies. The observation of strong bimodality for the electron up-flow direction in dual-inlaid Cu interconnects has added complexity, but is now widely accepted. More recently, bimodality has been reported also in down-flow electromigration, leading to very short lifetimes due to small, slit-shaped voids under vias. For a more thorough investigation of these early failure phenomena, specific test structures were designed based on the Wheatstone Bridge technique. The use of these structures enabled an increase of the tested sample size past 1.1 million, allowing a direct analysis of electromigration failure mechanisms at the single-digit ppm regime. Results indicate that down-flow electromigration exhibits bimodality at very small percentage levels, not readily identifiable with standard testing methods. The activation energy for the down-flow early failure mechanism was determined to be 0.83 ± 0.01 eV. Within the small error bounds of this large-scale statistical experiment, this value is deemed to be significantly lower than the usually reported activation energy of 0.90 eV for electromigration-induced diffusion along Cu/SiCN interfaces. Due to the advantages of the Wheatstone Bridge technique, we were also able to expand the experimental temperature range down to 150 °C, coming quite close to typical operating conditions up to 125 °C. As a result of the lowered activation energy, we conclude that the down-flow early failure mode may control the chip lifetime at operating conditions. The slit-like character of the early failure void morphology also raises concerns about the validity of the Blech-effect for this mechanism. A very small amount of Cu depletion may cause failure even before a stress gradient is established. We therefore conducted large-scale statistical experiments close to the critical current density-length product (jL)*. The results indicate that even at very small failure percentages, this critical product seems to extrapolate to about 2900 ± 400 A/cm for SiCOH-based dielectrics, close to previously determined (jL)* products of about 3000 ± 500 A/cm for the same technology node and dielectric material, acquired with single link interconnects. More detailed studies are currently ongoing to verify the extrapolation methods at small percentages. Furthermore, the scaling behavior of the early failure population was investigated.
Combinatorial Approaches to Investigations of Thermochromic Materials
Authors: Tang Hong , White Mary Anne
Published: August 2010

Thermochromic materials change color with temperature. Organic ternary mixtures composed of a dye, developer and solvent can reversibly change color with temperature. Although they are used in many commercial products, little is known about the detailed mechanism of thermochromism. Given the wide range of available components and compositions that could potentially show thermochromic behavior, we have embarked on combinatorial studies using inkjet printing to directly prepare thermochromic mixtures on paper.
Fabrication and Electrical Characterization of Metal-Silicide Nanocrystals for Nano Floating Gate Nonvolatile Memory
Authors: Han Seung Jong , Seo Ki Bong , Lee Dong Uk , Kim Eun Kyu , Oh Se-Mam , Cho Won-Ju
Published: August 2010

We have fabricated the nano-floating gate memory with the TiSi2 and WSi2 nanocrystals embedded in the dielectrics. The TiSi2 and WSi2 nanocrystals were created by using sputtering and rapidly thermal annealing system, and then their morphologies were investigated by transmission electron microscopy. These nanocrystals have a spherical shape with an average diameter of 2-5 nm. The electrical properties of the nano-floating gate memory with TiSi2 and WSi2 nanocrystals were characterized by capacitance-voltage (C-V) hysteresis curve, memory speed and retention. The flat-band voltage shifts of the TiSi2 and WSi2 nanocrystals capacitors obtained appeared up to 4.23 V and 4.37 V, respectively. Their flat-band voltage shifts were maintained up to 1.6 V and 1 V after 1 hr.
HfO2-based Thin Films Deposited by RF Magnetron Sputtering
Authors: Khomenkova Larysa , Dufour Christian , Coulon Pierre-Eugène , Bonafos Caroline , Gourbilleau Fabrice
Published: August 2010

HfO2-based layers prepared by RF magnetron sputtering were studied by X-ray diffraction, infrared absorption spectroscopy and transmission electron microscopy techniques. The effect of the deposition parameters and post-deposition annealing treatment on the properties of the layers was investigated. The amorphous-crystalline transformation of pure HfO2 layers is observed to be stimulated by annealing treatment at 800 ° C. It was found that the incorporation of silicon in HfO2 matrix allows to prevent crystallization of the layers and to shift the crystallization temperature to values up to 900 °C.
Key Technologies for FeRAM Backend Module
Authors: Ren Tian-Ling , Zhang Ming-Ming , Jia Ze , Wang Lin-Kai , Wei Chao-Gang , Xue Kan-Hao , Zhang Ying-Jie , Hu Hong , Xie Dan , Liu Li-Tian
Published: August 2010

Ferroelectric random access memory (FeRAM) is believed to be the most promising candidate for the next generation non-volatile memory due to its fast access time and low power consumption. Fabrication technologies of FeRAM can be divided into two parts: CMOS technologies for circuits which are standard and can be shared with traditional IC process line, and process relating to ferroelectric which is separated with CMOS process and defined as backend module. This paper described technologies for integrating ferroelectric capacitors into standard CMOS, mainly about modeling of ferroelectric capacitors and backend fabrication technologies. Hysteresis loop of the ferroelectric capacitor is the basis for FeRAM to store data. Models to describe this characteristic are the key for the design of FeRAM. A transient behavioral ferroelectric capacitor model based on C-V relation for circuit simulation is developed. The arc tangent function is used to describe the hysteresis loop. “Negative capacitance” phenomenon at reversing points of applied voltage is analyzed and introduced to the model to describe transient behaviors of the capacitor. Compact equivalent circuits are introduced to integrate this model into HSPICE for circuit simulation. Ferroelectric materials fabrication, electrodes integration and etching are the main technologies of FeRAM fabrication process. An metal organic chemical vapor deposition (MOCVD) process is developed to fabricate high quality Pb(Zr1-xTix)O3 (PZT) films. Pt is known to cause the fatigue problems when used as electrodes with PZT. Ir is used as electrodes to improve the fatigue property of PZT based capacitors, and mechanism of the fatigue is analyzed. Hard mask is used to reduce the size of the capacitors and damage caused in etching process. In our process, Al2O3 is developed as hard mask, which simplifies the FeRAM backend integration process.
Electrically-controlled Resistance Switching Accompanied by Ultra-high-J Domains of VO2 Films
Authors: Sakai Joe
Published: August 2010

The electric-field-induced resistance switching (EIRS) phenomenon on a VO2 planar-type junction fabricated on a Al2O3 (0001) substrate was studied by performing current-voltage (I-V) measurement and optical microscope observation simultaneously. It was confirmed that current density J of the low-resistance-state (LRS) region is maintained constant at approximately 1.6 × 106 A/cm2, while the volume of the LRS region was changed according to the current. A survey of the previous I-V traces on EIRS of VO2 revealed that almost all the junctions so far had shown non-zero V-intercepts, which are attributed to the volume change of the LRS regions. The maintenance of high-J in the LRS region is considered to be related to the electrically-induced metallic phase mechanism reported in perovskite-type manganites.
Conformal MOCVD Deposition of GeSbTe in High Aspect Ratio Via Structure for Phase Change Memory Applications
Authors: Zheng Jun-Fei , Chen Phil , Hunks William , Stender Matthias , Xu Chongying , Li Weimin , Roeder Jeff , Kamepalli Smuruthi , Schell Carl , Reed James , Ricker Jim , Sandoval Regino , Fournier Jeffery , Czubatyj Wally , Wicker Guy , Dennison Chuck , Hudgens Stephen , Lowrey Tyler
Published: August 2010

We have demonstrated conformal deposition of amorphous GeSbTe films in high aspect ratio structures by MOCVD. SEM analysis showed the as-deposited GeSbTe films had smooth morphologies and were well controlled for void free amorphous conformal deposition. GeSbTe films adhere well to SiO2, TiN, and TiAlN. The morphology and adhesion are stable in 420°C post process. By annealing at 365°C, amorphous GeSbTe films converted into crystalline GeSbTe with polycrystalline grain sizes of 5nm. Film resistivity in the crystalline phase ranged from 0.001 to 0.1 Ω-cm, suitable for device applications. Phase change devices fabricated with confined via structures filled with MOCVD GeSbTe showed cycle endurances up to 1×1010with a dynamic set/rest resistance of two orders of magnitude.
Emerging Technologies and Opportunities Based on the Magneto-Electric Effect in Multiferroic Composites
Authors: Vopsaroiu Marian , Blackburn John , Cain Markys G.
Published: August 2010

Multiferroic materials are recognized today as one of the new emerging technologies with huge potential for both academic research and commercial developments. Multiferroic composites are in particular more attractive for studies due to their enhanced properties, especially at room temperature, in comparison to the single-phase multiferroics. In this paper, we examine some of the theoretical aspects regarding one type of multiferroic composites (laminated structures) and we discuss one of the many possible applications of these exciting structures. We highlight the main advantages composite systems have over single-phase multiferroics and the similarities that exist between them.
Room Temperature Ferromagnetism and Lack of Ferroelectricity in Thin Films of ‘Biferroic’ YbCrO3
Authors: Nagar Sandeep , Rao K. V. , Belova Lyubov M. , Catalan G. , Hong J. , Scott James , Tyagi A. K. , Jayakumar O. D. , Shukla R. , Sheng Yi , Guo Jinghua
Published: August 2010

Search for novel multi-functional materials, especially multiferroics, which are ferromagnetic above room temperature and at the same time exhibit a ferroelectric behavior much above room temperature, is an active topic of extensive studies today. Ability to address an entity with an external field, laser beam, and also electric potential is a welcome challenge to develop multifunctional devices enabled by nanoscience. While most of the studies to date have been on various forms of Bi- and Ba based Ferrites, rare earth chromites are a new class of materials which appear to show some promise. However in the powder and bulk form these materials are at best canted antiferromagnetics with the magnetic transition temperatures much below room temperature. In this presentation we show that thin films of YbCrO3 deposited by Pulsed Laser Deposition exhibit robust ferromagnetic properties above room temperature. It is indeed a welcome surprise and a challenge to understand the evolution of above room temperature ferromagnetism in such a thin film. The thin films are amorphous in contrast to the powder and bulk forms which are crystalline. The magnetic properties are those of a soft magnet with low coercivity. We present extensive investigations of the magnetic and ferroelectric properties, and spectroscopic studies using XAS techniques to understand the electronic states of the constituent atoms in this novel Chromite. While the amorphous films are ferromagnetic much above room temperature, we show that any observation of ferroelectric property in these films is an artifact of a leaky highly resistive material.
Competing Magnetic Interactions in Magnetoelectric YbMnO3
Authors: Ray Shishir , Zou Ying , Williamsen Mark S. , Sen Somaditya , Buroker Larry , Guptasarma Prasenjit
Published: August 2010

We clarify here certain aspects of the magnetic field (H) – temperature (T) phase diagram of YbMnO3, a hexagonal Rare-Earth manganite oxide in which two multiferroic ordered states – ferroelectricity and antiferromagnetism coexist at low temperature. Single crystals of YbMnO3 were carefully grown from a Floating Zone (FZ) at low speed, then oriented and studied at variable temperature and magnetic field. Magnetization and heat capacity measurement show features corresponding to the antiferromagnetic (AFM) ordering of Mn3+, and the rare earth Yb3+. We find that the ordering temperature of Mn3+ is independent of applied magnetic field up to 5T. However, contrary to previous reports in flux-grown crystals, we do not observe a complete suppression of Yb3+ order above 0.1T. Instead, we find that Yb3+ remains at least up to 1 T, suggesting a revision of our current understanding of the ordering mechanism of the Mn-Yb and Yb –Yb sub-lattices in this hexagonal structure.
Electrodeposited Cu-In-Ga-Se Thin Films for CIGS-based Solar Cells
Authors: Bhattacharya Raghu
Published: August 2010

Cyclic voltammogram studies were performed on H2SeO3, CuSO4, In2(SO4)3, GaCl3, H2SeO3 + CuSO4 + In2(SO4)3 and H2SeO3 + CuSO4 + In2(SO4)3 + GaCl3 to understand the electrodeposition mechanism. The reduction potential from the cyclic voltammogram studies indicates that the first deposited layer is Cu from the Cu-In-Se and Cu-In-Ga-Se solution mixture. The subsequent deposition of the In and Ga layer is more favorable on the first-deposited Cu layer.
Electronic structure and phase stability of In-free photovoltaic semiconductors, Cu2ZnSnSe4 and Cu2ZnSnS4 by first-principles calculation
Authors: Maeda Tsuyoshi , Nakamura Satoshi , Wada Takahiro
Published: August 2010

We have theoretically evaluated the phase stability and electronic structure of Cu2ZnSnSe4 (CZTSe) and Cu2ZnSnS4 (CZTS). The enthalpies of formation for kesterite, stannite and wurtz-stannite phases of CZTSe and CZTS were calculated using a plane-wave pseudopotential method within the density functional formalism. For CZTSe, the calculated formation enthalpy (ΔH) of the kesterite phase (−312.7 kJ/mol) is a little smaller than that of the stannite phase (−311.3 kJ/mol) and much smaller than that of the wurtz-stannite phase (−305.7 kJ/mol). For CZTS, the ΔH of the kesterite phase (−361.9 kJ/mol) is smaller than that of the stannite phase (−359.9 kJ/mol) and much smaller than that of the wurtz-stannite phase (−354.6 kJ/mol). The difference of ΔH between the kesterite and stannite phases for CZTS is greater than that for CZTSe. This indicates the kesterite phase is more stable than the stannite phase in CZTS compared with CZTSe. The valence band maximums (VBMs) of both the kesterite- and stannite-type CZTSe(CZTS) are antibonding orbitals of Cu 3d and Se 4p (S 3p). The conduction band minimums (CBMs) are antibonding orbitals of Sn 5s and Se 4p (S 3p). The Zn atom does not affect the VBM or the CBM in either CZTSe(CZTS). The theoretical band gap of the kesterite phase calculated with sX-LDA in both CZTSe and CZTS is a little wider than that of the wurtz-stannite phase and much wider than that of the stannite phase.
Development of ZnTe Contacts for Cd1-xMgxTe Thin-Film Solar Cells for Tandem Applications
Authors: Duenow Joel N. , Dhere Ramesh , Li Jian , Metzger Wyatt K. , Duda Anna , Gessert Tim A.
Published: August 2010

Polycrystalline Cd1-xMgxTe (CMT) thin films are a potential absorber material for two-junction thin-film tandem solar cell applications because the desired top cell bandgap range of 1.6 to 1.8 eV is readily obtained using CMT with only small resultant changes in the lattice constant from that of CdTe. Tandem devices require the top cell to have a transparent back contact to transmit the sub-bandgap spectrum to the bottom cell. Sputtered Cu-doped ZnTe (ZnTe:Cu) thin films, which offer potential as a transparent back contact interface layer, have been used successfully in CdTe devices. We apply ZnTe:Cu back contacts to CMT devices to continue development toward a transparent top cell. We describe the effects of depositing ZnTe:Cu at different temperatures and with different Cu contents on the net acceptor concentration, minority carrier lifetime, and device performance. We present here the highest reported CMT device efficiency of 9.6% at a bandgap of 1.57 eV.
Enhancement of InGaN-based MQW Grown on Si(111) Substrate by Underlying AlGaN/GaN SLS Cladding Layer
Authors: Ahmad Shuhaimi Bin Abu Bakar , Suzue Takaaki , Nomura Yukiyasu , Maki Yoshinori , Egawa Takashi
Published: August 2010

This paper reports enhanced internal-quantum-efficiency (IQE) in InGaN-based multi-quantum-well (MQW) grown on Si(111) substrate with underlying strained-layer-superlattice (SLS) cladding layer for application in LDs and LEDs. In comparative study between a thick Al0.03Ga0.97N bulk and an Al0.06Ga0.94N/GaN SLS cladding layer, transmission-electron-microscopy (TEM) images reveal that Al0.06Ga0.94N/GaN SLS cladding layer is effective to suppress threading dislocations. A higher IQE has been achieved in sample with underlying Al0.06Ga0.94N/GaN SLS cladding layer, compared to that of Al0.03Ga0.97N bulk cladding layer. IQE of 31.6% has been achieved in sample with underlying Al0.06Ga0.94N/GaN SLS cladding layer when the MQW thickness is reduced to 2 nm.
ZnO Thin Film Deposition on Sapphire Substrates by Chemical Vapor Deposition
Authors: Chen Zhuo , Salagaj Tom , Jensen Christopher , Strobl Karlheinz , Nakarmi Mim , Shum Kai
Published: August 2010

ZnO thin films with thickness around 200 nm were deposited on a-plane sapphire substrates by Chemical Vapor Deposition (CVD) method with a mixed ZnO-powder/C-powder solid source. These films were characterized by Atomic Force Microscopy (AFM), Scanning Electron Microscopy (SEM), and photoluminescence (PL) spectroscopy. The correlation between surface structural properties of ZnO thin films and their optical signature measured by temperature dependence of PL is investigated for various growth conditions such as flow rate O2 injection gas and growth temperature. At room temperature, the columbic interaction enhanced absorption edge of 3.305 eV of these films was determined by optical absorption measurements.
Photooxidation of Water Using Vertically Aligned Nanotube Arrays: A comparative study of TiO2, Fe2O3and TaON nanotubes
Authors: Misra Mano , Banerjee Subarna , Mohapatra Susanta K , John Shiny E , Howard Cameron
Published: August 2010

There is a real need for a material which absorbs in the visible light of the solar spectrum, is stable in water and at the same time economical. One-dimensional vertically aligned nanotubes have contributed to a great extent towards the visible light driven photoelectrolysis of water. In this work, we give an overview of the different nanotubes obtained through anodization of various metals and their application in the photooxidation of water
Synthesis and Electrorheological Activity of Nanosized Particles of Hybrid Material Silica / Cetylpyridinium Chloride
Authors: Korobko Evguenia , Kouznetsova Tatyana , Novikova Zoya , Bedik Natalia , Zhurauski Mikalai
Published: August 2010

Hybrid organic-inorganic nanocomposite silica with surfactant � cetylpyridinium chloride with the polyphase structure, having a high electrorheological activity, is synthesized using sol-gel method. Physical-mechanical characteristics of dispersions based on mineral oil and synthesized powder with the concentration of 20 and 30 % by weight are investigated. The results of the shear stress measurements versus the strength of the dc and ac (frequency 50 Hz) electric fields (0 � 3.5 kV/mm) at Couette shear (shear rate 8 � 390 s) and yield stress in the range of temperatures 20 � 97 �C are presented. The comparative analysis of the results obtained with the results for the powder of the hybrid organic-inorganic nanocomposite silica/ polyethylene glycol is carried out.
Biological Applications of Programmable Optoelectrofluidic Manipulation
Authors: Park Je-Kyun
Published: August 2010

This paper presents a new programmable particle manipulation using a lab-on-a-display platform, which is a kind of optoelectrofluidic platform applying a liquid crystal display (LCD) as a display device for generating virtual electrodes in optoelectronic tweezers. The reconfigurable virtual electrodes in the lab-on-a-display are more advantageous than other devices which apply the micro-patterned electrodes, because we can freely control the size and position of electrodes as well as the voltage conditions, which affect the particle movements such as concentration and separation of particles. Due to its simple structures, cheap manufacturing costs, and high performances, this new LCD-based optoelectrofluidic platform can be applied to the interactive manipulation of polystyrene microspheres and blood cells. In addition, a method to discriminate normal oocytes for in vitro fertilization is demonstrated by combining the gravity effect with the optically induced positive dielectrophoresis (DEP). The discrimination performance can be enhanced due to the reduction of friction forces acting on the oocytes which are relatively large and heavy cells being affected by the gravity field. With the same device, we also demonstrate the size-dependent microparticle separation as well as the local concentration and assembly of microparticles originated from the image-driven AC electrokinetics such as DEP and AC electroosmosis. The particle movements result from the frequency-dependent behavior according to the particle diameter. This novel technique can be applied to rapidly concentrate, separate and pattern micro-/nanoparticles and biomolecules in many biological and chemical applications.
Fluidic Surface-Tension-Directed Self-Assembly of Miniaturized Semiconductor Dies Across Length Scales and 3D Topologies
Authors: Jacobs Heiko , Knuesel Robert J
Published: August 2010

This proceeding discusses recent progress on engineered fluidic surface-tension-directed self-assembly involving liquid solder. The process is applied to the assembly of discrete inorganic semiconductor device components at different length scales producing electrically interconnected devices and systems. Prior results include assembly with unique angular orientation and contact pad registration, parallel packaging, and the programmable assembly of various types of light emitting diodes. Recent progress on the scaling of the minimal die size from 300 to 30 μm is discussed which required the development of a new delivery system to concentrate and effectively introduce the components to solder-based receptors. Specifically, components are pre-oriented at a liquid-air or liquid-liquid interface and transferred onto the solder based receptors using a dynamic contact angle with a dipping process. Recent applications include the tiling of curved and 3D surfaces with single crystal semiconductors including the formation of flexible 3D solar cells.
An Integral Equation based Numerical Solution for Nanoparticles Illuminated with Collimated and Focused Light
Authors: Sendur Kursat
Published: August 2010

An integral equation based numerical solution is developed when the particles are illuminated with collimated and focused incident beams. The solution procedure uses the method of weighted residuals, in which the integral equation is reduced to a matrix equation and then solved for the unknown electric field distribution. In the solution procedure, the effects of the surrounding medium and boundaries are taken into account using a Green’s function formulation. Therefore, there is no additional error due to artificial boundary conditions unlike differential equation based techniques, such as finite difference time domain and finite element method. In this formulation, only the scattering nano-particle is discretized. The results are compared to the analytical Mie series solution for spherical particles, as well as to the finite element method for rectangular metallic particles. The Richards-Wolf vector field equations are combined with the integral equation based formulation to model the interaction of nanoparticles with linearly and radially polarized incident focused beams.
Chemical Nano-tomography of Self-assembled Ge-Si:Si(001) Islands from Quantitative High Resolution Transmission Electron Microscopy
Authors: Montoro Luciano Andrey , Leite Marina , Biggemann Daniel , Peternella Fellipe Grillo , Batenburg Kees Joost , Medeiros-Ribeiro Gilberto , Ramirez Antonio J.
Published: August 2010

The knowledge of composition and strain with high spatial resolution is highly important for the understanding of the chemical and electronic properties of alloyed nanostructures. Several applications require a precise knowledge of both composition and strain, which can only be extracted by self-consistent methodologies. Here, we demonstrate the use of a quantitative high resolution transmission electron microscopy (QHRTEM) technique to obtain two-dimensional (2D) projected chemical maps of epitaxially grown Ge-Si:Si(001) islands, with high spatial resolution, at different crystallographic orientations. By a combination of these data with an iterative simulation, it was possible infer the three-dimensional (3D) chemical arrangement on the strained Ge-Si:Si(001) islands, showing a four-fold chemical distribution which follows the nanocrystal shape/symmetry. This methodology can be applied for a large variety of strained crystalline systems, such as nanowires, epitaxial islands, quantum dots and wells, and partially relaxed heterostructures.
Hybrid Tomography of Nanostructures in the Electron Microscope
Authors: Saghi Zineb , Gnanavel Thirunavukkarasu , xu xiaojing , Möbus Guenter
Published: August 2010

A variety of tomographic experiments and modes for electron tomography of nanostructures are introduced, derived from the general concepts of quantitative computed tomography, binarised geometric tomography, including shape-from-silhouette, and spectroscopic chemical mapping. Our emphasis is on working out concepts of combining at least two of these tomography modes in order to share their respective advantages and improve the overall reconstruction quality. In this work, the following three hybrid modes are presented: (i) ADF-STEM tomography and EDX tomography into high-resolution 3D chemical mapping, (ii) geometric tomography and lattice-resolved backprojection into HREM-tomography for convex bodies, and (iii) geometric tomography and e-beam nanosculpting into “tomographic nanofabrication”.
Characterization of Nanostructured Organic-Inorganic Hybrid Materials Using Advanced Solid-State NMR Spectroscopy
Authors: Mao Kanmi , Rapp Jennifer L. , Wiench Jerzy W. , Pruski Marek
Published: August 2010

We demonstrate the applications of several novel techniques in solid-state nuclear magnetic resonance spectroscopy (SSNMR) to the structural studies of mesoporous organic-inorganic hybrid catalytic materials. Most of these latest capabilities of solid-state NMR were made possible by combining fast magic angle spinning (at ≥ 40 kHz) with new multiple RF pulse sequences. Remarkable gains in sensitivity have been achieved in heteronuclear correlation (HETCOR) spectroscopy through the detection of high-λ (1H) rather than low-λ (e.g., 13C, 15N) nuclei. This so-called indirect detection technique can yield through-space 2D 13C-1H HETCOR spectra of surface species under natural abundance within minutes, a result that earlier has been out of reach. The 15N-1H correlation spectra of species bound to a surface can now be acquired, also without isotope enrichment. The first indirectly detected through-bond 2D 13C-1H spectra of solid samples are shown, as well. In the case of 1D and 2D 29Si NMR, the possibility of generating multiple Carr-Purcell-Meiboom-Gill (CPMG) echoes during data acquisition offered time savings by a factor of ten to one hundred. Examples of the studied materials involve mesoporous silica and mixed oxide nanoparticles functionalized with various types of organic groups, where solid-state NMR provides the definitive characterization.
Mechanical Function of a Complex Three-dimensional Suture Joining the Bony Elements in the Shell of the Red-eared Slider Turtle
Authors: Shahar Ron , Kraus Stefanie , Monsonego-Ornan Efrat , Fratzl Peter
Published: August 2010

Certain design strategies appear repeatedly in a variety of biological structures. One such motif consists of a soft and pliable interface joining much larger and stiffer elements. Examples include the craniofacial sutures between the bones of the skull, the sutures between the bony plates in shell of turtles and the periodontal ligament between teeth and their sockets. Yet the detailed mechanics of these systems are not fully understood.

Turtles are believed to have existed already in the early Triassic, about 200 million years ago. They are thus one of the oldest non-extinct vertebrates. Their shell is therefore a particularly attractive subject for investigation since it has developed and conserved through such an extremely long evolutionary process and has achieved a highly optimized structure.

The turtle shell has a ‘sandwich’ structure typical of flat bones like the skull of vertebrates. It consists of two external, relatively thin sheets of dense bone (internal endocortical and external exocortical bone plates) which contain very few voids, and between them a thick and very porous spongy bone layer. At the mid-distance between adjacent ribs the dermal bones are separated by soft sutures which have a unique and complex 3-D shape.

The primary function of the shell is to protect the turtle from external trauma, and therefore it has to be stiff. However excessive stiffness may result in microdamage accumulation as a result of everyday activities like minor impact, and decrease the efficiency of respiration and locomotion. We speculate that the structure and architecture of the sutures allow easy deformation of the shell at small loads but cause it to become considerably more rigid at larger loads, reminiscent of composite materials with interlocking elements. We hypothesize that this mechanical property is related to the putative function of the suture in the turtle shell.

In order to examine this hypothesis we studied samples obtained from shells of the red eared slider turtle (Chrysemys scripta elegans). We used several imaging techniques (micro-computed tomography, scanning electron microscopy and light microscopy), histology and mechanical testing. Based on these observations we present a concept of the structure-mechanics relationship of the shell, and present a simple mathematical model of the deformation pattern of the suture-containing samples in 3-point bending tests and compare its predictions to our experimental results.
Adhesive Structure of the Freshwater Zebra Mussel, Dreissena polymorpha
Authors: Farsad Nikrooz , Gilbert Trevor W. , Sone Eli D
Published: August 2010

The freshwater Zebra Mussel,Dreissena polymorpha, was accidently released into the Great Lakes approximately 20 years ago. Since then it has spread rapidly, thanks in part to its ability to adhere to hard substrates, resulting in serious environmental and economic consequences. Like the marine mussels, attachment of the Zebra Mussel is achieved by means of its byssus, a series of proteinaceous threads that connect the animal to surfaces via secreted adhesive plaques. While the byssus of the Zebra Mussel is superficially similar to those of its marine counterparts, significant structural and compositional differences suggest that further investigation of the adhesion mechanisms in this freshwater species is warranted. Here we examine for the first time the detailed distribution of DOPA (3,4-dihydroxyphenylalanine)-containing proteins in the Zebra Mussel plaque and threads, as well as the enzyme responsible for their cross-linking. We show that the plaque-substrate interface retains the greatest amount of DOPA after aging, consistent with an adhesive role, while in the threads and bulk of plaque DOPA is presumably cross-linked for cohesive strength. We report also on a remarkably uniform layer ˜10 nm thick on the underside of the plaque, which is most likely responsible for adhesion.
Characterization of Crustacyanin-A2 Subunit as a Component of the Organic Matrix of Gastroliths from the Crayfish Cherax quadricarinatus
Authors: Luquet Gilles , Le Roy Nathalie , Zanella-Cléon Isabelle , Becchi Michel , Bucarey Sergio , Fernandez Maria Soledad , Arias Jose Luis , Guichard Nathalie , Marie Benjamin , Marin Frédéric
Published: August 2010

Like the lobsters, some terrestrial crabs and other crayfishes, the Australian red claw crayfish, Cherax quadricarinatus, elaborates in its stomach wall calcium storage structures called gastroliths. For understanding the cyclic elaboration and stabilization of these amorphous calcified structures, we studied the organic matrix (OM) of these paired biomineralizations. After decalcification with acetic acid, we analysed the proteinaceous components of an acetic acid-insoluble fraction by two-dimensional electrophoresis. Nine spots were digested by trpsin and the tryptic peptides were sequenced by nanoLC-nanoESI-MS/MS mass spectrometry. About 100 peptidic sequences were compared to sequences previously registered in the databases. Seven of the partially sequenced organic matrix polypeptides are probably new proteins. Another one corresponds to the previously sequenced protein, GAP65, from Cherax quadricarinatus and the last one, which migrates in electrophoresis at around 25 kDa, presents strong homology with the crustacyanin-A2 subunit of Homarus gammarus.
Superelasticity, Shape Memory and Stability of Nitinol Honeycombs under In-plane Compression
Authors: Shaw John A. , Michailidis Petros A , Triantafyllidis Nicolas , Grummon David S
Published: August 2010

Low density Nitinol shape memory alloy honeycombs were fabricated using a new Nb-based brazing method, which demonstrated enhanced shape memory and superelastic properties under in-plane compression. Adaptive, light-weight cellular structures present interesting possibilities for design of new architectures and novel applications. This paper presents an overview of ongoing work to address the multi-scale stability of superelastic, thin-walled, SMA honeycombs and the need for design and simulation tools.
Mechanically Reinforcing Polyacrylate/Polyacrylamide Hydrogels through the Addition of Colloidal Particles
Authors: Baker Bryan A , Murff Rebecca , Milam Valeria T
Published: August 2010

Polyacrylamide is a popular material for many bio-related applications ranging from electrophoretic separation to cellular supports. A limitation of polyacrylamide-based hydrogels, however, is their mechanical compliance. The current study examines the effect of colloidal particles as a reinforcing filler phase to enhance the mechanical stiffness of polyacrylamide-polyacrylate hydrogels. Measurements with oscillatory rheology show that for a fixed polymer volume fraction, the presence of colloidal particles with various surface modifications generally results in an increase of the shear storage modulus of the hydrogel-particle composite. Interestingly, this study indicated that no discernable trends can be linked between the values of the shear storage modulus and the particle surface characteristics.
SiGe channels for higher mobility CMOS devices
Authors: Naumann Andreas , Kelwing Torben , Trentzsch Martin , Kronholz Stephan , Kammler Thorsten , Flachowsky Stefan , Herrmann Tom , Kücher Peter , Bartha Johann W
Published: August 2010

Silicon germanium (SiGe) is considered to substitute silicon (Si) as channel material of p-type MOSFET in future CMOS generations due to its higher hole mobility. In this work we investigate SiGe channels with a germanium concentration of 23 at% and 30 at%, even though the mobility is expected to be higher with even more germanium in the alloy. Low pressure chemical vapor deposition was used for SiGe deposition. A state of the art CMOS process including high-k dielectric and metal gate electrode was applied for fabrication of sub 50 nm gate length devices. As expected from the SiGe channel conduction and valence band offset the threshold voltage of the devices is influenced. The gate stack was directly deposited onto the SiGe layer consisting of a chemically grown base oxide, hafnium-based dielectric and titanium nitride gate electrode. C-V and I-V measurements show comparable CET and leakage values for the high-k metal gate stack on Si and SiGe channels. The trap density at the channel dielectric interface was determined using the charge pumping technique. The device characteristics of n- and p-MOSFETs with SiGe channels are compared to conventional Si channel devices. Short channel mobility was extracted with the gM,LIN-Method.