bluuebunny/crossref_metadata_2025 huggingface dataset:
Measuring CET of High-k Dielectrics with Novel Kinetic Approach Using Micro-Site Corona – Kelvin Method
Authors: Marinskiy Dmitriy , Loy Thye Chong , Yeh H. C. , Wilson Marshall , Lagowski Jacek
Published: May 2014

Freshly deposited surfaces of high-k dielectrics revealed a new set of challenges for monitoring capacitance equivalent thickness, CET, using micro-site corona – Kelvin metrology. Specifically, ions deposited by corona discharge may have a queue-time dependent high surface diffusivity, which causes charge spreading away from charging spot under the Kelvin voltage probe. This could result in underestimation of dielectric thickness and unrepeatable results. To overcome this problem, we have developed a kinetic approach based on the analysis of the surface voltage transient after point source corona charging. The mathematical solution of the two-dimensional diffusion equation enables fitting of the voltage transient and reliable determination of two parameters: the surface diffusion coefficient and the dielectric capacitance. The latter one gives CET. The kinetic approach was applied to HfO2 layers deposited by atomic layer deposition. Repeatable CET measurements for a range of high-k surface conditions and thicknesses are presented. Elimination of queue-time dependence achieved with the novel kinetic approach is a significant advantage for fab-line monitoring.
(Invited) Selective-Area Metal Organic Vapor-Phase Epitaxy of InGaAs/InP Heterostrucures on Si for Advanced CMOS Devices
Authors: Merckling Clement , Waldron Niamh , Jiang Sijia , Guo Weiming , Ryan Paul , Collaert Nadine , Caymax Matty , Barla Kathy , Heyns Marc , Thean Aaron , Vandervorst W.
Published: May 2014

This study relates to the heteroepitaxy of InP buffer and InxGa1-xAs channel layers on patterned Si substrates using the defect trapping technique. We focused on the optimization and control of the InP buffer layer in STI trenches to obtain low defect density and high mobility InxGa1-xAs channel layer. The demonstration of III-V heteroepitaxy at scaled dimensions opens the possibility for new applications integrated on Silicon.
Temperature Dependence of Defect Evolution and Distribution in Thermally Cycled Cu-TSVs
Authors: Marro James Brandon , Okoro Chukwudi A , Obeng Yaw S. , Richardson Kathleen A , Chamma Karima
Published: May 2014

Copper (Cu) through-silicon vias (TSV) were thermally cycled using three cycling profiles, which were differentiated by peak cycling temperature. Signal loss in the TSVs escalated with peak cycling temperature for some samples due to the resulting increased void content. This void area increase was attributed to the formation of new voids and not growth of pre-existing voids. The Cu microstructure in the TSVs appeared to be unaffected by the cycling. The Cu was not preferentially oriented and contained a substantial amount of twins.
(Invited) Gate Stacks for Silicon, Silicon Germanium, and III-V Channel MOSFETs
Authors: Frank Martin M. , Zhu Yu , Bedell Stephen W. , Ando Takashi , Narayanan Vijay
Published: May 2014

High-k gate dielectrics such as HfO2 and metal gates such as TiN have been deployed across a wide range of silicon-based CMOS logic products. In some gate-first technologies, SiGe channels (cSiGe) have been implemented simultaneously for threshold voltage control in p-channel metal-oxide-semiconductor field-effect transistors (pMOSFET). Herein, we review aspects related to the impact of high-k/channel interfacial layers on Si, SiGe, and III-V gate stack quality and device performance. First, we review remote oxygen scavenging approaches for interfacial SiO2 thinning in HfO2/Si nFET and HfO2/cSiGe pFET devices. We show that they allow equivalent oxide thickness (EOT) to be reduced to 0.4-0.5 nm, and we discuss device performance and reliability tradeoffs that may limit continued EOT scaling. For later technology nodes, high-carrier-mobility III-V semiconductors channels such as InGaAs are under consideration. We summarize three high-k/InGaAs channel interface approaches: Direct high-k deposition, Si capping, and InP capping.
(Invited) Temperature Impact on Reliablity and Manufacturing of Embedded HfOx-Based RRAM: a Novel Pre-coding Method for Bypassing Soldering Reflow
Authors: Tirano Sauveur , Perniola Luca , Cagli Carlo , Jalaguier Eric , Jousseaume Vincent , Deleruyelle Damien , Muller Christophe , de Salvo Barbara , Reimbold Gilles
Published: May 2014

This paper proposes a novel pre-coding method that enables bypassing the soldering reflow issue in resistive memory devices called RRAM. This method is based on the difference between forming and set voltages distributions to discriminate virgin memory cells from those in which data were pre-coded before the soldering step. This procedure enables data recovery through the application of a voltage pulse over the whole memory array. This method, demonstrated on bipolar HfO2-based resistive elements, can be extended to all RRAM devices that exhibit a significant margin between forming and set voltages distributions.
The Improvement of FN Degradation in 3-Dimension TR
Authors: Ha Sung Yeob , Park Se Geun , Kim Shin Deuk , Kim Hyun Chul , Lee Kyu Pil , Jung Il Sub
Published: May 2014

Recently, there are many unexpected problems in short channel device. Among these problems, FN degradation has been a serious problem that induces reliability failure in the device as the thickness of gate oxide becomes thinner. Various solutions to solve this problem have been considered, especially in this paper you can confirm the result that FN degradation can be solved by improving fin structure and adjusting the condition of TiN deposition. It is assumed that fin structure is important to reduce leakage current and the control of grain size is helpful to decrease fixed charges generation. These methods are very useful solutions without current loss in the short channel device.
(Invited) Spatial ALD, Deposition of Al2O3 Films at Throughputs Exceeding 3000 Wafers per Hour
Authors: Granneman Ernst H.A. , Kuznetsov Vladimir I. , Vermont P.
Published: May 2014

Al2O3 is the first ALD film being introduced in the solar cell (PV) industry. The primary driver for implementation is two-fold: excellent surface passivation and low cost-of-ownership. ‘Spatial’ ALD systems satisfy both criteria. On Fz and Cz-type wafers minority carrier lifetimes in the range of 5-8 and 0.5-1ms, respectively, are obtained. With this type of film, PERC-type cells with efficiencies > 20% were realized. Further, such cells are processed with throughputs > 3000 wafers/hr. The thermal stability of the film is improved by selecting thin films (< 6nm), and by carrying out a post-deposition anneal at 600°C. This anneal drives out excess hydrogen that is incorporated during deposition, thereby avoiding the formation of blisters upon exposure to subsequent high-temperature (‘firing’) steps.
High Selectivity in Dry Etching of Silicon Nitride over Si Using a Novel Hydrofluorocarbon Etch Gas in a Microwave Excited Plasma for FinFET
Authors: Nakao Yukihisa , Matsuo Takatoshi , Teramoto Akinobu , Utsumi Hidetoshi , Hashimoto Keiichi , Kuroda Rihito , Shirai Yasuyuki , Sugawa Shigetoshi , Ohmi Tadahiro
Published: May 2014

Increased etch selectivity of SiNx over Si is required for the gate spacer formation in miniaturized MISFETs, especially in the FinFET. In this work, the selectivity of SiNx over Si is evaluated using a novel hydrofluorocarbon etch gas with a microwave excited high-density plasma. By using this novel etchant gas, a higher selectivity of SiNx over Si was obtained compared to CH3F. The etch rate of Si was suppressed due to the deposition of a hydrocarbon film on Si surface without O2 gas. It was found that the selectivity of SiNx over Si near the SiNx sidewall decreased compared that far from the SiNx sidewall. By using flow rates of more than 12 sccm of the novel CxHyFz gas, the gate spacer was formed without Si recess even after the SiNx was overetched for an equivalent thickness of 40 nm.
Atomic Layer Deposition of Sidewall Spacers: Process, Equipment and Integration Challenges in State-of-the-Art Logic Technologies
Authors: Belyansky Michael P. , Conti Richard , Khan Shahrukh , Zhou Xin , Klymko Nancy R , Yao Yiping , Madan Anita , Tai Leo , Flaitz Philip , Ando Takashi
Published: May 2014

The paper discusses the properties of silicon nitride and silicon oxide spacer films from the perspectives of ALD (Atomic Layer Deposition) and MLD (Molecular Layer Deposition) techniques, precursor chemistries and compositional stability after implant anneals and spacer sculpting reactive ion etching processes. Advanced imaging techniques like EELS (Electron Energy Loss Spectroscopy) and SIMS (Secondary Ion Mass Spectrometry) techniques have been used to analyze sidewall spacer processes. Special attention has been paid to the microloading effect - the dependence of thin film deposition rate on pattern density. The effect of ALD deposition parameters on film electrical characteristics like dielectric breakdown and leakage are also delineated.
(Invited) Quantum Capacitance Measurement of Bilayer Graphene
Authors: Nagashio Kosuke , Kanayama Kaoru , Nishimura Tomonori , Toriumi Akira
Published: May 2014

We demonstrate a considerable suppression of the low-field leakage through a Y2O3 topgate insulator on graphene by applying high-pressure O2 at 100 atm during post-deposition annealing. Then, two kinds of issues, band gap opening and inter-band scattering at high carrier density, are discussed through the density of states of bilayer graphene estimated by the quantum capacitance measurement.
(Henry B. Linford Award for Distinguished Teaching Address) Low Temperature Plasma Etching of Copper, Silver, and Gold Films
Authors: Hess Dennis W.
Published: May 2014

Copper, silver and gold films possess unique electrical and optical properties that render them suitable for various device structures as employed in integrated circuits and plasmonic devices. Traditional etching of these metal films in halogenated plasmas is difficult due to the low vapor pressure of halogenated metal species. Reasonable etch rates of Cu, Ag, and Au films are obtained with hydrogen-based plasmas. Pattern formation with hydrogen and methane plasmas yields excellent selectivity to barrier materials such as Ta and Ti and generates metal wall slopes of ~80o.
(Invited) P-Type III-Sb MOSFET on a Metamorphic Substrate: Towards All III-V CMOS
Authors: Madisetti Shailesh , Tokranov Vadim , Greene Andrew , Yakimov Michael , Sasaki Shun , Hirayama Makoto , Novak Steven , Bentley Steven , Jacob Ajey , Oktyabrsky Serge
Published: May 2014

A study of lattice-mismatched epitaxial growth and related defects and their effects on electrical characteristics of hetero-epitaxial III-Sb films grown on Si is presented in this paper. Growth of 800 nm thick GaSb on Si results in a threading dislocation density of ~6x108 cm-2; density of planar defects such as microtwins of ~2x104 cm-1 and anti-phase domain boundaries on the order of ~104 cm-1, respectively. High defect-related acceptor-type doping is also observed, the effect of which is to change polarity from n-type to p-type, whilst p-type MOS shows similar characteristics as grown on GaAs substrate. The main surface features of strained InGaSb layers grown on metamorphic AlSb or AlGaSb buffers on Si are elongated bumps due to microtwins: however, hole mobility of ~650 cm2/V-s has been obtained in a buried strained quantum well channel. In this work, we study the use of the migration enhanced epitaxy technique for the growth of AlSb seed layers on Si to improve InGaSb quality.
Analysis of High Aspect Ratio through Silicon via (TSV) Diffusion and Stress Impact Profile during 3D Advanced Integration
Authors: Djomeni Larissa , Mourier Thierry , Minoret Stéphane , Fadloun Sabrina , Barnes Jean-Paul , Rouchon Denis , Burgess Steve , Price Andrew , Vandroux Laurent , Mathiot Daniel
Published: May 2014

This article is related to the development of a protocol for the characterization of the behavior of high aspect ratio through silicon via (TSV) during advanced three dimension (3D) integration. The time-of-flight (TOF)-SIMS profile measurement along the sidewall of the TSV with advanced samples preparations is described. This technique allows studying the efficiency of a low temperature, 200°C metallorganic chemical vapor deposition (MOCVD) titanium nitride (TiN) film as a barrier to copper diffusion into silicon. Then the thermo-mechanical stresses induced by the TSV in the surrounding silicon were studied by micro-Raman spectroscopy. Different TiN films were studied according to subsequent plasma treatments and compared with a reference deposited by ionized physical vapor deposition (i-PVD). The thermal stress in the silicon was found to decrease as a function of distance from an isolated TSV. The iPVD and MOCVD TiN barrier involved a more compressive stress than non-plasma treated MOCVD TiN.
Low-Cost MEMS Packaging Using Polymer-Based Air-Gaps
Authors: Uzunlar Erdal , Kohl Paul A
Published: May 2014

The improvements in microelectromechanical systems (MEMS) have been traditionally focused more on the functionality and sensitivity of devices. However, packaging of MEMS devices has become a bottleneck mainly due to a wide range of device dimensions and packages being device-specific. In this study, we present a low-cost, sacrificial polymer-based MEMS packaging using air-gaps. Air-gaps were fabricated with poly(propylene carbonate) (PPC) as the sacrificial material and Cyclotene 4026 (BCB) as the overcoat. BCB was found to provide excellent mechanical support for the air cavity during the decomposition of the sacrificial material at high temperature and after decomposition at room temperature. Initial results were found to be promising in terms of before-and-after resonant spectra changes, i.e. <0.1% change in resonant frequency, and <5.2% change in quality factor. Two possible schemes of air-gap MEMS packaging are presented: (i) air-gap structures with BCB overcoat cap, and (ii) air-gap structures without BCB overcoat cap. Both schemes utilize epoxy overmolding as the protective layer.
Positive Tone, Low-k Polynorbornene Dielectric Crosslinking
Authors: Schwartz Jared , Mueller Brennen K , Kohl Paul A
Published: May 2014

The effect of pH on film properties is studied in epoxy-based polynorbornene dielectrics. During normal processing, the negative tone films exhibit a highly acidic pH prior to cure, whereas the positive tone films exhibit a neutral or basic pH. Films with the exposed photo acid generator were swelled with base to achieve a comparable pH to the positive tone material. Despite the contrast in film acidity, a peak modulus of 3.0 GPa at a 140ºC cure temperature was observed, declining to 2.4 GPa at 220ºC for both negative tone pH conditions. In a neutral pH positive tone material, crosslinking occurred with DNQ acting as the cross-linker, providing a modulus of 4.0 GPa. When developed, DNQ-loaded films showed a decline in modulus to 2.6 GPa, likely due to the reactions of DNQ with aqueous base. An epoxy cross-linker added to the developed positive tone film helped crosslinking by inhibiting base uptake.
(Invited) (ECS Electronics & Photonics Division Award )Wafer-Level Step-Stressing of InGaP/GaAs HBTs
Authors: Baca Albert G. , Kotobi Joshua A. , Fortune Torben R. , Gorenz Alan , Klem John F. , Briggs Ronald D. , Clevenger J. B. , Patrizi Gary A.
Published: May 2014

Wafer-level step-stress experiments on high voltage Npn InGaP/GaAs HBTs are presented. A methodology utilizing brief, monotonically increasing stresses and periodic, interrupted parametric characterization is presented. The method and various examples of step-stressed HBTs illustrate the value of the technique for screening the reliability of HBT wafers. Degradation modes observed in these InGaP/GaAs HBTs closely correspond to a subset of those in other, longer types of reliability experiments and can be relevant in a reliability screen. A statistical sampling of HBT wafers reveals a consistently realized critical destructive limit over a very narrow power range, which indicates that thermal stress is the main cause of degradation. When stepped just shy of the destructive limit, electrical characteristics are capable of revealing gradual degradation. The end state of stressing typically involves shorting of both the base-emitter and base-collector junctions. Interrupted characterization revealed cases where base-emitter shorts preceded base-collector shorts and other cases where base-collector shorts occurred first. Examples of degradation include reductions in reverse breakdown voltage, increases in the offset voltage, and drops in current gain. These wafer-level step-stress techniques show promise for reducing the large time lag between wafer fabrication and useful reliability screening in HBTs.
(Invited) GaN HEMT Fabrication in a 200mm Si Foundry Environment: The Time Has Come
Authors: Laroche J. , Ip K. , Breen M. , Hoke W. , Cao Y. , Bettencourt J. , Guenther D. , Gebara G. , Kennedy T. , Schultz B. , Laboutin O. , Fong C. , Trimble T. , Johnson W. , Kazior T. , Comeau J.
Published: May 2014

In 2013 Raytheon began to integrate deep submicron (≤0.25 µm gate) 200mm GaN on Si HEMT processes within a commercial CMOS Si Foundry environment. When fully realized, these processes will demonstrate multi GHz GaN on Si MMICs by leveraging a fully subtractively processed transistor coupled with multi level copper based back end of line (Cu BEOL) processes. This work provides a status update on the progress towards that goal.
(Invited) Deep Ultraviolet Light Emitting Diodes: Physics, Performance, and Applications
Authors: Shur Michael , Gaska Remis , Dobrinsky Alex , Shatalov M.
Published: May 2014

The key factor for developing deep UV LEDs is material’s quality of nitride epitaxial films. It could be dramatically improved by using novel MEMOCVD® technique. Using very narrow quantum wells (QWs) and energy band gap engineering in deep UV LEDs improves overlap between electron and hole wave functions and increases the Internal Quantum Efficiency (IQE) and External Quantum Efficiency (EQE). A novel transparent and reflecting top contact further boosts IQE and EQE and increases the power output and high external quantum efficiency of our Deep UV LEDs. Research is now under way to use these devices for improving quality and extending storage time of fruits and vegetables. Other applications include water and air purification, sterilization, biological threat identification, applications in medicine, biology, industrial processes, defense, and homeland security.
(Invited) Flexible 3-Dimensional Graphene Foam-Based NO2 Gas Sensors
Authors: Lee Chongmin , Kim Byung-Jae , Kim JiHyun
Published: May 2014

Flexible three-dimensional (3-D) graphene foam-based NO2 gas sensors on polyethylene terephthalate (PET) substrates were demonstrated. The thickness of graphene layers was analyzed by micro-Raman spectroscopy. Currents of the relaxed and strained (1%) 3-D graphene foam-based NO2 gas sensors after the repetitive exposure of 200 ppm NO2 gas for 3 minutes were increased by ~ 0.42 mA and ~ 0.35 mA, respectively. The changes in currents and resistance in different strain conditions were also characterized. The robustness, excellent electrical conductivity and high surface-to-volume ratio of 3-D graphene foam show great potentials for advanced flexible gas sensors.
(Invited) Vertical-Geometry GaN-Based Light-Emitting Diodes: Improving Current Injection and Light Extraction Efficiencies
Authors: Choi Y.-W. , Yum W.-S. , Seong Tae-Yeon
Published: May 2014

The effect of an indium middle layer on the structural, thermal and electrical properties of Ag contacts for high-power GaN-based vertical LEDs was investigated. As the temperature increases, agglomeration is initiated by the formation of hillocks, followed by the generation of holes, leading to agglomeration. The In layer effectively prevents agglomeration. Consequently, the In-inserted Ag reflectors exhibit better reflectivity at 500°C than Ag only contacts. The In-inserted Ag sample was less <111>-textured than the Ag only sample. On the basis of the scanning electron microscopy, and X-ray phi scan and pole figure results, the improved stability is described by means of the <111>-texture and the modification of the surface energy of Ag films. The In-inserted Ag reflectors exhibit better specific contact resistivity at 500°C than Ag only contacts. The output power (at 20 mA) of LEDs with the In-inserted Ag contacts is higher than that of LEDs with Ag only contacts.
(Invited) Effects of Environmental Exposure on Stability and Conductance Poly-l-lysine Coated AlGaN/GaN High Electron Mobility Transistors
Authors: Rohrbaugh Nathaniel , Bryan Isaac , Bryan Zachary , Collazo Ramon , Ivanisevic Albena
Published: May 2014

AlGaN/GaN HEMTs have been shown promise to be used as in-situ biosensors. An inquiry was done into the stability of physisorption as a method of adhering surface bioactive molecules to the surface of the HEMT gate contacts. Poly-l-lysine (30,000 MW) was used to coat AlGaN/GaN field effect transistors as a representative charged biomolecule for biosensing applications. Coated FETs were then exposed to 1 and 4 hour soaks in DI water at ambient temperature. Atomic force microscopy (AFM) and conductance measurements (IV) were used to quantify current decay and surface morphology changes. Analysis of the results showed that charged analytes readily adsorbed onto the surface. Upon adsorption an immediate signal decay was observed. The changes after soaking in solution were variable. The results point to the need to develop specific chemistry that will result in stable immobilization of biomolecules onto the device surface. Such stability is necessary for long- term reliable device operation.
Superatmospheric MOCVD Growth of Bulk InGaN for Template and Optoelectronic Applications
Authors: Conway Matthew , Deguzman Panfilo C , Stokes E. B.
Published: May 2014

InGaN, a III-Nitride semiconductor, has bandgaps between 0.7 eV (InN) and 3.39 eV (GaN), covering the entire visible spectrum, which makes InGaN an important material for photonic applications. To utilize the full range of InGaN’s bandgap, methods for material growth with increased indium content must be established. MOCVD synthesis of InGaN with indium content higher than approximately 20% has been difficult to achieve while maintaining high crystal quality. There is evidence that superatmospheric MOCVD growth can establish such a method. Work by Cheng Li et. al. indicates that the photoluminescent intensity increases with pressure, while thermodynamics indicate favorable conditions for superatmospheric growth. Growths of GaN and InGaN were done at 1.5 bar-a, with promising results. GaN was successfully grown with low yellow band luminescence and high indium composition material was grown, confirmed by X-Ray diffraction. The possibility of superatmospheric growth of high indium content InGaN was confirmed.
(Invited) Crystal Defects in Wide Bandgap Semiconductors
Authors: Shenai Krishna , Christou Aristos , Dudley Michael , Ragothamachar Balaji , Singh Rajendra
Published: May 2014

The state-of-the-art power switching devices made from SiC and GaN semiconductors contain a high density of crystal defects. Most of these defects are present in starting wafers and some are generated during device processing. There is little conclusive evidence so far on the exact role that the crystal defects paly on device performance, manufacturing yield, and more importantly, long-term field-reliability especially when devices are operating under extreme stressful environments. This paper provides a review of the current state-of-the-art of SiC and GaN power semiconductor material technology, and the potential impact crystal defects may have on high-density power switching electronics. A review of silicon technology development and manufacturing evolution is made to draw a parallel between silicon and wide bandgap (WBG) semiconductor power electronics.
Ti/Al/Ni/Cu Ohmic Contact with Low Contact Resistance and Smooth Surface Morphology for AlGaN/GaN HEMT
Authors: Wong Yuen-Yee , Chang Edward Yi , Chen Yu-Kong , Liu Shih Chien , Lin Yueh-Chin , Maa Jer-Shen
Published: May 2014

The feasibility of replacing the Au layer in a conventional ohmic contact of Ti/Al/Ni/Au for AlGaN/GaN structure with Cu has been investigated. While the thicknesses of Ti, Al and Cu layers were fixed throughout the study, the thickness of Ni layer was varied to examine its influence on the Cu-based ohmic contacts. It is showed that the Ni layer thickness played an important role in the Ti/Al/Ni/Cu metallization for achieving low contact resistance and smooth surface morphology. With a 50-Å Ni layer, a low specific contact resistance (rc) of 1.35x10-6 ohm-cm2 has been realized. This result is comparable with the conventional ohmic contact (rc = 1.19x10-6 ohm-cm2). High electron mobility transistor (HEMT) devices fabricated using both Au- and Cu-based ohmic contact exhibited similar DC characteristics, suggesting that the electrical performance did not degrade with the used of Cu in the ohmic contact. Furthermore, in the absence of Au, the surface roughening caused by Au-Al alloy in the conventional ohmic contact was also prevented. As a result, the root-mean-square roughness of the optimized Cu-based contact was only 7.62 nm as compared to 134 nm for the conventional structure.
TiO2 Nanowires/ZnO Nanosheets Hierarchically Structure on Ti Foil as Flexible Photoanodes for Dye-Sensitized Solar Cells
Authors: Gao Rui , Cui Yixiu , Liu Xiaojiang , Wang Liduo , Cao Guozhong
Published: May 2014

In this paper, a novel TiO2 Nanowires/ZnO Nanosheets (TiO2 NW/ZnO NS) hierarchical structure has been fabricated on Ti foil substrate through a two-step process of hydrothermal and homogenous precipitation. DSSCs device based on such structured flexible photoanode showed a significantly improvement of power conversion efficiency compared to that based on TiO2 NWs, which increased from 0.80% to 1.41% under 100 mW cm-2 illumination, enhancing 76.2% relatively. The improvement of conversion efficiency is mainly due to the much larger surface area and resulting increased dye-loading amount and photocurrent of TiO2 NW/ZnO NS hierarchical structure.
Structural and Optical Properties of Luminescent Silicon Carbonitride Thin Films
Authors: Khatami Zahra , Wilson Patrick Robert James , Taggart Owen , Frisina Dan R , Wojcik Jacek , Mascher Peter
Published: May 2014

The composition, structure, and optical characteristics of amorphous hydrogenated silicon carbonitride (a-SiCN:H) thin films were investigated as a function of nitrogen content. The electron cyclotron resonance plasma enhanced chemical vapor deposition (ECR PECVD) technique was utilized to fabricate two different types of a-SiCN:H thin films including films with varying nitrogen contents and films co-doped with cerium and terbium. The intensity and position of the photoluminescence (PL) peak could be tuned in the visible range by controlling the film composition, deposition conditions, and post-deposition thermal treatment. Near edge X-ray absorption fine structure (NEXAFS) spectroscopy at the Si K- and N K-edge were used to perform a comparative structural study on a series of CVD grown a-SiCN:H thin films. A correlation was obtained between the amount of nitrogen in the matrix and the PL behaviour, which also supported the trend in the NEXAFS results.
(Invited) Inhomogeneous Strain in Silicon Photonics
Authors: Wehrspohn Ralf , Schriever Clemens , Schilling Jörg
Published: May 2014

The lack of a dipolar second order susceptibility (χ(2)) in silicon due to its centrosymmetric diamond lattice usually inhibits efficient second order nonlinear optical processes in the silicon bulk. Depositing stressed silicon nitride layers or growing a thermal oxide layer introduces an inhomogeneous strain into the silicon lattice and breaks the centrosymmetry of its crystal structure thereby creating a χ(2). This causes enhanced second harmonic generation and was observed in reflection and transmission measurements for wavelengths in the infrared. However strain is not the only means to break the structures symmetry. Fixed charges at the silicon nitride/silicon interface cause a high electric field close to the silicon interface which causes electric-field-induced-second-harmonic (EFISH) contributions too. The combination of both effects leads to χ(2) values which are estimated to be of the order as classic χ(2) materials like KDP or LiNiO3. This paves the way for the exploitation of other second order nonlinear processes in the area of silicon photonics and is an example how fundamental optical properties of materials can be formed by strain.
(Invited) Flexible GHz Frequency and Low-Power Nanoelectronics Based on 2D Nanomaterials
Authors: Akinwande Deji , Chang Hsiao-Yu , Lee Jongho
Published: May 2014

In this paper, substantial recent progress on graphene and transitional metal dichalcogenides on flexible substrates and the resulting high-performance electronic properties will be highlighted. Nearly defect-free monolayer graphene can now be synthesized by CVD at large-scales with material quality comparable to ex-foliated natural flakes. Fabricated transistor devices from CVD graphene on polyimide now readily afford transit frequencies around 25GHz, sufficient to realize radio-frequency circuits. Exfoliated dichalcogenides offer a route for basic experimental studies on soft substrates. MoS2 transistors on polyimide offer electronic performance comparable to devices on hard silicon substrates, including high on-off current ratio, near-ideal subthreshold swing, and current saturation. Device failure at high strains are either due to dielectric cracks or buckle delamination.
(Invited) Effects of Annealing Process on Morphology, Crystal Structure, and Photoelectrical Properties of CZTS Thin Films
Authors: Cao Lei , Sui Jing , Zhang Qian , Zhu Qianqian , Dong Hongzhou , Dong Lifeng
Published: May 2014

In this paper, Cu2ZnSnS4 (CZTS) thin films were directly formed on FTO glass substrates by a simple ethanol-thermal method, and the films were annealed at 550 oC under different atmospheric environments. Field emission scanning electron microscopy, energy dispersive spectroscopy, X-ray powder diffraction, and photoelectrical measurements were conducted to investigate effects of annealing parameters on surface morphology, chemical compositions, crystal structures, and photoelectrical properties of the thin films. All the thin films were smooth and compact, but their color and micro-topography were different through different annealing atmospheres. The addition of sulfur during the annealing process is necessary to tailor sulfur concentration in the films and the crystallization of CZTS phase.
Synthesis of High Quality Few Layer Graphene from the Exfoliation of Graphite
Authors: Bai Jincheng , Soden Daniel R. , Dong Lifeng
Published: May 2014

This study aims to synthesize high quality few layer graphene through exfoliation of graphite, accomplished through continuous addition of a Triton X-100 surfactant solution to a graphite suspension during sonication lasting for 50, 80, 110, 140, 170, and 200 min, respectively. The resulting suspension was then filtrated to separate out the graphene, before being tested for quality through scanning electron microscopy, X-ray diffraction and Raman spectroscopy. It was revealed that graphite had been exfoliated into few layer graphene after a short sonication time (less than 50 min). And the quality of graphene was improved with the sonication time increased, indicated by the reduced number of graphene layers. This completely physical method of graphene synthesis provides a simple way to achieve the highly desired few layer graphene, and will hopefully allow for greater use of graphene in industry and its implementation into new technology.
Suspended Carbon Nanowire-Based Structures for Sensor Platforms
Authors: Lim Yeongjin , Heo Jeong-Il , Shin Heungjoo
Published: May 2014

In this report, fabrication of monolithic suspended carbon nanowire-based structures including single nanowire and nanomeshes, and their applications as electrochemical/gas/bio-sensors are introduced. The suspended carbon structures are fabricated using the carbon-MEMS process consisting of conventional UV-lithography and pyrolysis which accompanies significant volume shrinkage resulting in the formation of complex suspended carbon nanostructures. The suspended carbon nanowires shows good robustness enough to be processed with photolithography and deposition; this enables patterning of functional materials in sub-micromenter scale without any nanofabrication technologies. The single suspended carbon nanowires of 200 nm diameter can be selectively coated with a thin palladium or ZnO nanowires which showed good gas sensing capability down to 20 ppm hydrogen gas and 50 ppm CO, NOx, H2 gases respectively. Combined with a substrate-bound carbon band electrode, the suspended carbon mesh showed high efficiency of redox cycling enabling highly sensitive sensing of dopamine and glucose.
C-MEMS Based Microsupercapacitors and Microsensors
Authors: Song Yin , Agrawal Richa , Hao Yong , Chen Chunhui , Wang Chunlei
Published: May 2014

The rapid development of miniaturized electronic devices has led to a growing need for rechargeable micro-power sources with high performances. Miniaturized micro-supercapacitors have great potential to replace batteries and electrolytic capacitors in different types of applications. Carbon microelectromechanical systems (C-MEMS) technique, in which patterned photoresist is pyrolyzed in an inert environment at a high temperature is a powerful approach to fabricate high aspect ratio carbon microelectrode arrays, which could be a promising platform for various micro-power applications. To further improve the electrochemical properties of the carbon microelectrodes, different nanomaterials could be integrated by electrostatic spray deposition (ESD). This review provides an overview of our research at FIU on micro-supercapacitors with different structural designs and active materials.
Electrochemical Properties of Boron-Doped Diamond Thin Film Synthesized by MPCVD on Titanium Substrate to Use as an Ozone Generator
Authors: Park YeongMin , Kim DaeWook , Kim JeongWan , Cho Hyoung J. , Cho Hyun , Kim JinKon , Kim TaeGyu
Published: May 2014

Boron-doped diamond (BDD) has been attracting special attentions as a suitable electrode material for water disinfection due to its high chemical and electrochemical stability. In this paper, we had succeeded to generate ozone by using the BDD electrode with high efficiency and more safely compared to traditional lead oxide (PbO2) electrode. The BDD film was deposited on the Ti substrate by microwave plasma chemical vapor deposition to use as an anode for ozone kit. The morphology of samples were observed by Scanning Electron Microscopy (SEM) and the structural-chemical properties of synthesized diamond layer was investigated by Raman Spectroscopy. Conductivity, carrier concentration and Hall mobility was determined by a Hall-effect measurement unit, based on the van der Pauw method. The Ozone concentration in water, which was measured by Ozone Colorimeter.
Nasal Region Dimensions in Children: A CT Study and Clinical Implications
Authors: Likus Wirginia , Bajor Grzegorz , Gruszczyńska Katarzyna , Baron Jan , Markowski Jarosław
Published: May 2014

Atresias of nasal cavity, especially in young children, pose an essential problem in children’s otolaryngology. Only a few morphometric studies of nasal cavity concerning healthy neonates and young infants without nasal stenosis are available. Multislice computed tomography is a perfect tool enabling a precise evaluation of anatomic structures. The aim of this study was a complex morphometric evaluation of clinically important bone and mucosal structures of nasal cavity and examination of their dependence on age and sex in children up to 3 years of age. 180 children, age range 0–3 years, were divided into 5 age groups, and measurements of 18 distances between skeletal structures and between mucosal structures of nasal cavity were performed on their CT scans. A correlation between the widths of selected bone structures was examined. There were no statistically significant differences in analyzed morphometric parameters between adjacent age groups. The differences were statistically significant only between extreme age groups. There was a correlation between evaluated structures and age. Our results are a valuable supplement of nasal cavity morphometric data of young children. They may be useful in setting reference values of evaluated parameters in children and in diagnosis and planning of surgical treatment in children’s otolaryngology.
Wave Breaking for the Modified Two-Component Camassa-Holm System
Authors: Lv Wujun , Zhu Weiyi
Published: May 2014

Some new sufficient conditions to guarantee wave breaking for the modified two-component Camassa-Holm system are established.
The Efficacy of Balance Training with Video Game-Based Therapy in Subacute Stroke Patients: A Randomized Controlled Trial
Authors: Morone Giovanni , Tramontano Marco , Iosa Marco , Shofany Jacob , Iemma Antonella , Musicco Massimo , Paolucci Stefano , Caltagirone Carlo
Published: May 2014

The video game-based therapy emerged as a potential valid tool in improving balance in several neurological conditions with controversial results, whereas little information is available regarding the use of this therapy in subacute stroke patients. The aim of this study was to investigate the efficacy of balance training using video game-based intervention on functional balance and disability in individuals with hemiparesis due to stroke in subacute phase. Fifty adult stroke patients participated to the study: 25 subjects were randomly assigned to balance training with Wii Fit, and the other 25 subjects were assigned to usual balance therapy. Both groups were also treated with conventional physical therapy (40 min 2 times/day). The main outcome was functional balance (Berg Balance Scale-BBS), and secondary outcomes were disability (Barthel Index-BI), walking ability (Functional Ambulation Category), and walking speed (10-meters walking test). Wii Fit training was more effective than usual balance therapy in improving balance (BBS: 53 versus 48,P=0.004) and independency in activity of daily living (BI: 98 versus 93,P=0.021). A balance training performed with a Wii Fit as an add on to the conventional therapy was found to be more effective than conventional therapy alone in improving balance and reducing disability in patients with subacute stroke.
The Role of Uric Acid in Kidney Fibrosis: Experimental Evidences for the Causal Relationship
Authors: Kim Il Young , Lee Dong Won , Lee Soo Bong , Kwak Ihm Soo
Published: May 2014

Hyperuricemia is a common finding in chronic kidney disease due to decreased uric acid clearance. The role of uric acid as a risk factor for chronic kidney disease has been largely debated, and recent studies suggested a role of uric acid in the causation and progression of kidney fibrosis, a final common pathway in chronic kidney disease. Uric acid and xanthine oxidase may contribute to kidney fibrosis mainly by inducing inflammation, endothelial dysfunction, oxidative stress, and activation of the renin-angiotensin system. Besides, hyperuricemia induces alterations in renal hemodynamics via afferent arteriolopathy and contributes to the onset and progression of kidney fibrosis. Xanthine oxidase inhibitors may prevent kidney damage via lowering uric acid and/or inhibiting xanthine oxidase. However, there is still no sufficient evidence from interventional clinical researches supporting the causal relationship between uric acid and kidney fibrosis. The effect and role of xanthine oxidase inhibitors in preventing kidney fibrosis and chronic kidney disease progression must be further explored by performing future large scale clinical trials.
7-Tesla Magnetic Resonance Imaging Precisely and Noninvasively Reflects Inflammation and Remodeling of the Skeletal Muscle in a Mouse Model of Antisynthetase Syndrome
Authors: Sciorati Clara , Esposito Antonio , Campana Lara , Canu Tamara , Monno Antonella , Palmisano Anna , De Cobelli Francesco , Del Maschio Alessandro , Ascheman Dana P. , Manfredi Angelo A. , Rovere-Querini Patrizia
Published: May 2014

Inflammatory myopathies comprise heterogeneous disorders. Their etiopathogenesis is poorly understood, because of the paucity of informative experimental models and of approaches for the noninvasive study of inflamed tissues. Magnetic resonance imaging (MRI) provides information about the state of the skeletal muscle that reflects various facets of inflammation and remodeling. This technique has been scarcely used in experimental models of inflammatory myopathies. We characterized the performance of MRI in a well-established mouse model of myositis and the antisynthetase syndrome, based on the immunization of wild-type mice with the amino-terminal fragment of histidyl-tRNA synthetase (HisRS). Over an eight-week period following myositis induction, MRI enabled precise identification of pathological events taking place in muscle tissue. Areas of edema and of active inflammation identified by histopathology paralleled muscle modifications detected noninvasively by MRI. Muscles changes were chronologically associated with the establishment of autoimmunity, as reflected by the development of anti-HisRS antibodies in the blood of immunized mice. MR imaging easily appreciated muscle damage and remodeling even if actual disruption of myofiber integrity (as assessed by serum concentrations of creatinine phosphokinase) was limited. Thus, MR imaging represents an informative and noninvasive analytical tool for studyingin vivoimmune-mediated muscle involvement.
Identification of Virulence Factors Genes inEscherichia coliIsolates from Women with Urinary Tract Infection in Mexico
Authors: López-Banda Daniela A. , Carrillo-Casas Erika M. , Leyva-Leyva Margarita , Orozco-Hoyuela Gabriel , Manjarrez-Hernández Ángel H. , Arroyo-Escalante Sara , Moncada-Barrón David , Villanueva-Recillas Silvia , Xicohtencatl-Cortes Juan , Hernández-Castro Rigoberto
Published: May 2014

E coliisolates (108) from Mexican women, clinically diagnosed with urinary tract infection, were screened to identify virulence genes, phylogenetic groups, and antibiotic resistance. Isolates were identified by MicroScan4 system; additionally, the minimum inhibitory concentration (MIC) was assessed. The phylogenetic groups and 16 virulence genes encoding adhesins, toxins, siderophores, lipopolysaccharide (LPS), and invasins were identified by PCR. Phylogenetic groups distribution was as follows: B1 9.3%, A 30.6%, B2 55.6%, and D 4.6%. Virulence genes prevalence wasecp98.1%,fimH86.1%,traT77.8%,sfa/focDE74.1%,papC62%,iutA48.1%,fyuA44.4%,focG2.8%,sfaS1.9%,hlyA7.4%,cnf-1 6.5%,cdt-B0.9%,cvaC2.8%,ibeA2.8%, andrfc0.9%. Regarding antimicrobial resistance it was above 50% to ampicillin/sulbactam, ampicillin, piperacillin, trimethoprim/sulfamethoxazole, ciprofloxacin, and levofloxacin. UropathogenicE. coliclustered mainly in the pathogenic phylogenetic group B2. The isolates showed a high presence of siderophores and adhesion genes and a low presence of genes encoding toxins. The high frequency ofpapCgene suggests that these isolates have the ability to colonize the kidneys. High resistance to drugs considered as first choice treatment such as trimethoprim/sulfamethoxazole and fluoroquinolones was consistently observed.
Frequency and Clinical Implication of the R450H Mutation in the Thyrotropin Receptor Gene in the Japanese Population Detected by Smart Amplification Process 2
Authors: Tsunekawa Katsuhiko , Yanagawa Yoshimaro , Aoki Tomoyuki , Morimura Tadashi , Araki Osamu , Kimura Takao , Ogiwara Takayuki , Kotajima Nobuo , Yanagawa Masumi , Murakami Masami
Published: May 2014

In Japanese pediatric patients with thyrotropin (TSH) resistance, the R450H mutation in TSH receptor gene (TSHR) is occasionally observed. We studied the frequency and clinical implication of the R450H mutation inTSHRin the general population of Japanese adults using smart amplification process 2 (SmartAmp2). We designed SmartAmp2 primer sets to detect this mutation using a drop of whole blood. We analyzed thyroid function, antithyroid antibodies, and this mutation in 429 Japanese participants who had not been found to have thyroid disease. Two cases without antithyroid antibodies were heterozygous for the R450H mutation inTSHR. Thus, the prevalence of this mutation was 0.47% in the general population and 0.63% among those without antithyroid antibodies. Their serum TSH concentrations were higher than the average TSH concentration not only in subjects without antithyroid antibodies but also in those with antithyroid antibodies. The R450H mutation inTSHRis relatively common in the Japanese population and potentially affects thyroid function. The present study demonstrates that the SmartAmp2 method is useful to detect the R450H mutation inTSHR, which is one of the common causes of TSH resistance in the Japanese population.
Potential risk of alpha-glucosidase inhibitor administration in prostate cancer external radiotherapy by exceptional rectal gas production: a case report
Authors: Nishimura Takuya , Yamazaki Hideya , Iwama Kazuki , Oota Yoshitaka , Aibe Norihiro , Nakamura Satoaki , Yoshida Ken , Okabe Haruumi , Yamada Kei
Published: May 2014

Introduction

Radiotherapy is a standard treatment for prostate cancer, and image-guided radiotherapy is increasingly being used to aid precision of dose delivery to targeted tissues. However, precision during radiotherapy cannot be maintained when unexpected intrafraction organ motion occurs.

Case presentation

We report our experience of internal organ motion caused by persistent gas production in a patient taking an alpha-glucosidase inhibitor. A 68-year-old Japanese man with prostate cancer visited our institution for treatment with helical tomotherapy. He suffered from diabetes mellitus and took an alpha-glucosidase inhibitor. Routine treatment planning computed tomography showed a large volume of rectal gas; an enema was given to void the rectum. Subsequent treatment planning computed tomography again showed a large volume of gas. After exercise (walking) to remove the intestinal gas, a third scan was performed as a test scan without tight fixation, which showed a sufficiently empty rectum for planning. However, after only a few minutes, treatment planning computed tomography again showed extreme accumulation of gas. Therefore, we postponed treatment planning computed tomography and consulted his doctor to suspend the alpha-glucosidase inhibitor, which was the expected cause of his persistent gas. Four days after the alpha-glucosidase inhibitor regimen was suspended, we took a fourth treatment planning computed tomography and made a treatment plan without gas accumulation. Thereafter, the absence of rectal gas accumulation was confirmed using daily megavolt computed tomography before treatment, and the patient received 37 fractions of intensity-modified radiotherapy at 74Gy without rectal gas complications. In this case study, the alpha-glucosidase inhibitor induced the accumulation of intestinal gas, which may have caused unexpected organ motion, untoward reactions, and insufficient doses to clinical targets.

Conclusions

We suggest that patients who are taking an alpha-glucosidase inhibitor for diabetes should discontinue use of that particular medicine prior to beginning radiotherapy.