bluuebunny/crossref_metadata_2025_split huggingface dataset:
Phase Stability of 10mol%Sc2O3-1mol%CeO2-ZrO2 Ceramics
Authors: Yarmolenko Sergey , Fialkova Svitlana , Pai Devdas M. , Sankar Jag 
Published: April 2011

ABSTRACTScandia-doped zirconia is a very promising material for solid oxide fuel cells due to its high oxygen conductivity in the 700-850°C temperature range. 10 mol% Sc2O3 - 1 mol% CeO2 - ZrO2 ceramics were sintered at temperatures 1100-1600°C using different heating rates and dwell times. Ceramics sintered at temperatures higher 1300°C were found to exist in cubic phase at room temperature and exhibit slow phase transformation from cubic (c) to rhombohedral (beta) phase between 330 and 400°C. Analysis of c-β phase transition efficiency in the ceramics shows a strong correlation between the transition rate and sintering temperature. Kinetics of phase transitions were studied by high temperature X-ray diffractometry (HTXRD) and differential scanning calorimetry methods. The reversible c-β phase transition was found to have very wide hysteresis (45-70°C), which depends on sintering temperature and density. Coefficients of thermal expansion of c- and β-phases were calculated from temperature dependence of lattice parameters obtained by HTXRD in the temperature range of 25-800°C. Microstructural changes on the surface of the cubic phase due to c-β phase transition studied by SEM and AFM.
Preparation of Long Lasting Phosphor by New Method
Authors: Jin Hu , Xiaoqin Zhu , Donghua Chen , Kaijun Wan , Yuzhong Guo 
Published: April 2011

ABSTRACTThe composite powder of Al(OH)3 and Sr(OH)2, was obtained by means of the hydrolysis of the activated Al-Sr alloy powder in pure water. As a precursor, it could be used to prepare long after phosphor Eu, Dy co-doped SrAl2O4 by the modified solid state reaction at 1300°C. The components and microstructure of the composite powder were investigated by XRD, SEM and EDS techniques, and the luminescent characteristics and the afterglow properties of the long afterglow material were also measured at the same time. The experimental results showed that, the distribution of the two elements Al and Sr was uniform in the microstructure of the composite powder, and the contacting surfaces between the solid reactants were increased effectively at high temperature, and the diffusive paths were abbreviated. Therefore, the reaction velocity was increased, the sinter temperature descended and the luminescent properties enhanced.
Synthesis and characterization of colloidal titania nanoparticles
Authors: Díaz-Fonseca Ana-Lilia , Cheang-Wong Juan-Carlos 
Published: April 2011

ABSTRACTSpherical submicrometer-sized titanium dioxide (TiO2 or titania) particles were prepared by the sol-gel method from hydrolysis and condensation of titanium alkoxide using different basic catalysts in ethanol/acetonitrile at different annealing temperatures. A systematic study was performed in order to determine the effect on the particle size and shape of the different reagents. Subsequently, they were deposited onto silicon wafers, in order to form a monolayer of TiO2 monodisperse particles. The titania particles were characterized by scanning electron microscopy to determine size and shape, and by X-ray diffraction to find their crystal structure.
RF SOP (System On Package) Using Passive Embedded Substrate
Authors: Kang NamKee , Kim Junchul , Kim Dongsu , Yoo ChanSei , Ryu JongIn , Cho Hyunmin 
Published: April 2011

ABSTRACTThe convergence paradigm of today, which can be characterized as multi function and high effectiveness, strongly requires an integration of RF/analog function and high-speed digital function into a single IC or package. System on Package (SOP) is a promising technology for system integration in order to meet these current trends and requirements. A passive embedded substrate is one of the most critical issues to achieve small-size and high-functional devices and modules with high integration density and deign flexibility for wireless communications.This paper will describe integration approach for passive embedded substrate for RF applications. With the several examples such as multi-band front end module and passive/active integrated modules, the advantages of the integration using passive embedded substrates will be described with some design considerations.
Piezoelectric Materials for Advanced Integrated RF Components
Authors: Al Ahmad Mahmoud , Coccetti Fabio , Plana Robert 
Published: April 2011

AbstractThis paper will first address the piezoelectric material characterization using a capacitance measurement technique. An original simple and efficient technique for the determination of the d33 piezoelectric coefficient of lead zirconate titanate thin films is described. Classical capacitor plate theory and piezoelectric material analysis are used to calculate the capacitance variation in lead zirconate titanate film, enabling piezo-electric coefficient to be determined. The technique outlined here avoids the use of mechanical/optical apparatus that may require heavy preparation of sample substrate geometry. Then, this work also treats design and fabrication issues associated with innovative tunable front-end components which combine two different ceramic technologies, namely multilayer ceramic circuit boards (low temperature cofired ceramics or LTCC) and piezoelectric actuator technology within a single device.
Low-Power Liquid Lens Having Si Cylinder Chamber for Capsule Endoscope
Authors: Seo Sangwon , Han Seungoh , Seo Jun-Ho , Kim Young-Mok , Kang Moon-Sik , Min Nam-Gi , Choi Woo-Bum , Sung Man-Young 
Published: April 2011

ABSTRACTThe liquid lens based on MEMS technology can be an appropriate solution to improve the imaging capability of a capsule endoscope because it can be realized small enough and also consume negligible power. In this paper, a cylinder-type liquid lens was designed to minimize the dead area and then fabricated with MEMS technology combining the silicon thin-film process and the wafer bonding process where the multiple dielectric layer of Teflon, silicon nitride and thermal oxide was formed on the cylinder wall. The focal length of the lens module including the fabricated liquid lens was changed reproducibly as a function of the applied voltage. With the change of 30V in the applied bias, the focal length of the constructed lens module could be tuned in the range of about 42cm. The fabricated liquid lens was also proven to be small enough to be adopted in the capsule endoscope, which means the liquid lens can be utilized for the imaging capability improvement of the capsule endoscope.
Structural and photoconducting properties of MBE and MOCVD grown III-nitride double-heterostructures
Authors: Hauguth-Frank Sindy , Lebedev Vadim , Tonisch Katja , Romanus Henry , Kups Thomas , Büchner Hans-Joachim , Jäger Gerd , Ambacher Oliver , Schober Andreas 
Published: April 2011

ABSTRACTInvestigations on standing wave (SW) interferometry come in focus of interest in the course of ongoing miniaturization of high precision length measurement systems. A key problem within these efforts is the development of a transparent ultra-thin photodetector for sampling the intensity profile of the generated SW. Group III-materials are promising candidates to ensure a good photodetector performance combined with the required optical transparency. In this work, we report on the interrelation of strain and dislocation density along with the influence of the structural properties on the sensitivity of double-heterostructure III-nitride photodetectors grown by molecular beam and metal organic vapour phase epitaxy.
A Buried Silicon Nanocrystals Based High Gain Coefficient SiO2/SiOX/SiO2 Strip-Loaded Waveguide Amplifier on Quartz Substrate
Authors: Lian Cheng-Wei , Lin Gong-Ru 
Published: April 2011

ABSTRACTSi-rich SiOX strip-loaded waveguide with silicon (Si) nanocrystals contributed amplified spontaneous emission at 750-850 nm with associated spectral linewidth of 140 nm is characterized. By using variable stripe length (VSL) method we demonstrate the optical gain and loss coefficients of 65 and 5 cm−1, respectively, for such a waveguide amplifier. The optical gain and loss coefficients are observed by fitting the one dimensional amplifier equation. The small-signal power gain of 18.4 dB at wavelength of 805 nm under He-Cd laser pumping of 40 mW at 325 nm is obtained from the SiO2/SiOX/SiO2 waveguide amplifier with length of 1 cm.
Advanced Laser Diode Cooling Concepts
Authors: Feeler Ryan , Junghans Jeremy , Stephens Edward , Kemner Greg , Barlow Fred , Wood Jared , Elshabini Aicha 
Published: April 2011

ABSTRACTA new, patent-pending method of cooling high-power laser diode arrays has been developed which leverages advances in several areas of materials science and manufacturing. This method utilizes multi-layer ceramic microchannel coolers with small (100's of microns) integral water channels to cool the laser diode bar. This approach is similar to the current state-of-the-art method of cooling laser diode bars with copper microchannel coolers. However, the multi-layer ceramic coolers offer many advantages over the copper coolers, including reliability and manufacturing flexibility. The ceramic coolers do not require the use of deionized water as is mandatory of high-thermal-performance copper coolers.Experimental and modeled data is presented that demonstrates thermal performance equal to or better than copper microchannel coolers that are commercially available. Results of long-term, high-flow tests are also presented to demonstrate the resistance of the ceramic coolers to erosion. The materials selected for these coolers allow for the laser diode bars to be mounted using eutectic AuSn solder. This approach allows for maximum solder bond integrity over the life of the part.
Non-selective optical wavelength-division multiplexing devices based on a-SiC:H multilayer heterostuctures
Authors: Vieira Manuela , Fernandes Miguel , Louro Paula , Vieira Manuel Augusto , Barata Manuel , Fantoni Alessandro 
Published: April 2011

ABSTRACTIn this paper we present results on the optimization of multilayered a-SiC:H heterostructures for wavelength-division (de) multiplexing applications. The non selective WDM device is a double heterostructure in a glass/ITO/a-SiC:H (p-i-n) /a-SiC:H(-p) /a-Si:H(-i')/a-SiC:H (-n')/ITO configuration. The single or the multiple modulated wavelength channels are passed through the device, and absorbed accordingly to its wavelength, giving rise to a time dependent wavelength electrical field modulation across it. The effect of single or multiple input signals is converted to an electrical signal to regain the information (wavelength, intensity and frequency) of the incoming carriers. Here, the (de) multiplexing channels is accomplished electronically, not optically. This approach has advantages in terms of cost since several channels share the same optical components; and the electrical components are typically less expensive than optical ones. An electrical model gives insight into the device operation
Tailoring Quantum Dot Saturable Absorber Mirrors for Ultra-Short Pulse Generation
Authors: Lumb Matthew , Clarke Edmund , Farrell Dominic , Damzen Michael , Murray Ray 
Published: April 2011

ABSTRACTWe have designed and grown a series of quantum dot semiconductor saturable absorber mirrors (QD-SESAMs) for a range of operating wavelengths, incorporating innovative design and processing features to optimise the device performance. Using a range of reflectivity studies, ellipsometric measurements and both time-integrated and time-resolved spectroscopic studies, we have conducted detailed investigations of device performance. Extensive modelling work of dielectric multilayers has been undertaken which supports our experimental findings and allows us to understand and design novel structures in order to improve and tailor device characteristics, including dielectric capping and non-normal incidence. We demonstrate samples designed for operation with the higher excited-states of the QDs which produced a self-starting train of mode-locked pulses with a temporal duration of 200 ps at a repetition rate of 78 MHz in a Nd:YVO4 solid-state laser. We also present SESAMs incorporating electronically coupled QD bilayers, allowing long wavelength operation.
Effect of Ag and Au doping on the photocatalytic activity of TiO2 supported on textile fibres
Authors: Uddin Mohammed Jasim , Cesano Federico , Scarano Domenica , Bordiga Silvia , Zecchina Adriano 
Published: April 2011

ABSTRACTA simple method to develop TiO2, Ag or Au-doped TiO2 thin films on cotton textiles for advanced applications, is reported. The homogeneous TiO2 thin films have been deposited on cotton textiles by using sol-gel method at low temperature (100° C), whereas Ag and Au nanoparticles were then deposited on the pre-existent TiO2 films by photoreduction. The Ag/TiO2 covered cotton fibres show multichromic behaviour (grey colour under visible light and brown colour upon ultraviolet light exposure) as well as photoactivity. The Au-TiO2 film coated the cotton textile produces a purple colour with excellent self cleaning properties. The original and treated fibres have been characterized by several techniques (SEM, HRTEM, FTIR, Raman, UV–vis spectroscopy and XRD).
Printing of Patterned Copper on Pliable, Microtextured PDMS/Ceramic Composites
Authors: Apaydin Elif , Zhou Yijun , Hansford Derek , Koulouridis Stavros , Volakis John 
Published: April 2011

AbstractIn this work, we present a novel printing technique that enables the usage of PDMS and ceramic powder mixed PDMS composites (we refer as “PDMS-ceramic composites” in this context), as a substrate for printing of copper conduction layers. This technique is based on microtransfer molding (μTM) and lift-off for pattern formation [4]. Another key feature is the usage of microtextured PDMS and PDMS-ceramic composites before any copper film deposition. Our microtextured surface is composed of pyramid shaped wells (100 μm depth and 150 μm sides on PDMS surface). The poor adhesion between PDMS and copper is overcome by oxygen plasma application and titanium deposition before copper layer.In order to demonstrate the convenience of this technique in RF applications, copper conduction lines (5 mm wide, different lengths) were printed on microtextured PDMS substrates. These transmission lines successfully maintained a low resistance during large strain. The printed lines have the DC resistance of 0.5 Ω and conductivity of 1.3e6 S/m, and the transmission analysis of these lines show good results especially in the MHz range when compared to copper tape measurements.Apart from the conduction lines, the substrates can have ranging dielectric constants from 3 (no powder) to 23 (50% D270 powder, provided by TransTech) by volume mixing rule. Dielectric constant is important for RF applications, especially antenna designs. Therefore, provided with a range of dielectric constants, these composite substrates are a great promise in RF field for pliable antenna fabrication [5]. For experiment purposes, some of the transmission lines are printed on these composite substrates as well as pure PDMS.In this study, apart from the fabrication of transmission lines, this novel technique will be applied in a GPS antenna design for demonstration purposes. This antenna design is a single-fed circularly-polarized stacked antenna for tri-band GPS (L1, L2 and L5) applications [6]. For the fabrication of the antenna, polymer-ceramic materials of ε1=16 and ε2=30 will be utilized as the substrates [6].
Fracture Mechanisms of SiNx Thin-films on Compliant Substrates
Authors: Kattamis Alex Z , Cherenack Kunigunde H , Cheng I-Chun , Long Ke , Sturm James C , Wagner Sigurd 
Published: April 2011

AbstractThe prospect of large-area electronics on polymers, for flexible applications requires a study of thin film fracture mechanisms. To fabricate thin-film transistor (TFT) backplanes on polymer foils the substrate must first be passivated to protect the polymer substrate from chemicals used during processing and to protect the TFTs from substrate out gassing. Silicon nitride (SiNx) is commonly used for this purpose since it tends to adhere well to polymers and is easily deposited by PE-CVD. When rigid thin films such as SiNx are deposited onto compliant substrates, such as polymer foils, stresses caused by built-in strains and the mismatch in coefficients of thermal expansion can cause fracture. The deposited thin films may fracture, and also the polymer substrate below. Using focused-ion beam milling and scanning electron microscopy we analyzed two distinct thin film fracture morphologies for SiNx films on two different types of polymer substrate. One had a relatively low, the other a relatively high coefficient of thermal expansion. For both SiNx/substrate systems the SiNx was under residual compressive stress and the substrate under tension. In one case the compressive stress in the thin films cause them to debond, buckle, and crack. In the other case the tensile stress in the substrate causes it to tear, followed by the fracture of the SiNx film above.
Selective Oxidation and Resistivity Reduction of Cu-Mn Alloy Films for Self-forming Barrier Process
Authors: Iijima Jun , Fujii Yoshito , Neishi Koji , Koike Junich 
Published: April 2011

ABSTRACTOptimum conditions of annealing atmosphere and temperature for the reduction of Mn content from the Cu-Mn alloy layer in Cu-Mn self-forming barrier process were investigated. Mn was selectively oxidized at the surface by annealing in Ar gas containing an impurity level of O2 (<0.01ppm). Resistivity of the film was decreased to 2.0 μΩcm after annealing. On the other hand, internal oxidation of Cu-Mn alloy was observed with no external protective surface oxide layer in Ar containing more than 10 ppm of O2. An optimum oxygen concentration is found to be in between 0.01 and 10 ppm in 1atm of Ar gas at 350 °C.
Formation of Mn Oxide with Thermal CVD and its Diffusion Barrier Property Between Cu and SiO2
Authors: Neishi Koji , Aki Shiro , Iijima Jun , Koike Junichi 
Published: April 2011

ABSTRACTA manganese oxide layer was formed by thermal chemical vapor deposition(CVD) on a tetraethylorthosilicate (TEOS) oxide substrate. The thickness of the Mn oxide layer could be varied 2.6 to 10 nm depending on deposition temperature. Heat-treated samples of PVD Cu / CVD Mn oxide /SiO2 indicated no interdiffusion. The CVD Mn oxide was found to be a good diffusion barrier layer.
Effects of Pulse Duration and Polarity on the Electromigration Behavior of Copper Interconnects under Pulsed Current Stress
Authors: Lim Meng Keong , Gan Chee Lip , Ee Yong Chiang , Ng Chee Mang , Zhang Bei Chao , Tan Juan Boon 
Published: April 2011

ABSTRACTDirect current (D.C.) is usually employed to characterize the electromigration reliability of interconnects. However, D.C. characterization techniques might not reflect the actual reliability of interconnects that are carrying pulsed D.C. or A.C. (alternating current) signals during operation. This study investigates the effects of unipolar and bipolar pulsed current on the electromigration lifetime of copper (Cu) interconnects. A series of long period pulsed current (i.e. 2, 16, 32 and 48 hours) were applied to Cu interconnects. Lifetime enhancement is observed when the half-period of pulsed current is shorter than the medium-time-to-failure (t50) of D.C. stressed samples. Minor increase in resistance occurring in-between pulses for unipolar pulsed current stressed samples, and occurrence of damage healing in bipolar pulsed current stressed samples are reasons attributed for the observed enhanced lifetime. We obtained longer MTF when the period of the pulsed current is shorter.
Semiconductor Film Bonding Technology and Application in Two-axis Hall Sensor Fabrication
Authors: Koh Keishin , Matushita Takashi , Hohkawa Koji 
Published: April 2011

ABSTRACTWe study basic problems of the semiconductor film bonding technology. We propose a new releasing method for a large number of semiconductor films using the film photoresist to protect the semiconductor films. We investigated the basic process conditions. We successfully released a large number of the GaAs film and bonded them on the Si, LiNbO3 substrates and metal Au surface. We estimated the ctystallinity of semiconductor films by X-ray diffraction and Raman spectral. The results clarified that these process were effective. As an application of the semiconductor film bonding technology, we fabricated a two-axis Hall sensor with planar structure. The two-axis hall sensor can measure axial and radial magnetic filed components (Bx and Bz) with a sensitivity of about 9.2 Ω/G for Bz and 4.5 Ω/G for Bx respectively.
Copper CMP with Composite Polymer Core - Silica Shell Abrasives: A Defectivity Study
Authors: Armini Silvia , Whelan Caroline M. , Moinpour Mansour , Maex Karen 
Published: April 2011

ABSTRACTThe results of copper Chemical Mechanical Planarization (CMP) experiments with a model slurry chemistry based on the combination of Glycine-water-Benzotriazole (Gly-H2O2-BTA), and different types of composite A (silane coupling agents between the polymer core and the silica shell) and B (electrostatic attraction between the polymer core and the silica shell) abrasives, are presented. While the presence of BTA allows a ten-fold reduction in the static etch rate from 95 nm/min. to 10 nm/min., combining oxidizer and complexing agent leads to removal rates higher than 400 nm/min. Different surface morphology and RMS roughness are observed after polishing with composite abrasives and different peroxide concentrations. Oxidizer concentrations as low as 0.1 vol.% lead to high non-uniformity and defectivity values. In particular, composite B performs better than pure colloidal/fumed silica during copper CMP using the IC-1000 pad, giving comparable Material Removal Rate (MRR), but a better surface finish due to the contribution of the elasticity of the polymer in gently transferring the applied load to the wafer surface. Cu CMP with pure polymer particles is a promising alternative to the hard inorganic material especially if combined with suitable surfactants that act from both particle stabilization and friction reduction / lubrication improvement perspectives.The use of the medium/high-hardness pad IC-1000 is compared to the use of a soft Politex pad. In the former case, differences in terms of MRR, MRS roughness, and total defects are observed between the composite abrasives A and B; in the latter case, the behaviour of the two composites is similar. In the case of a soft pad in combination with composite abrasives, there is a remarkable improvement in the defectivity without any loss in MRR.As revealed by SEM inspection of the composite particles collected in the slurry drain after CMP, for all the composites, the silica shell coverage is not disrupted by the shear forces and chemistry during the 1 min. polishing. Consequently, the stability and agglomeration properties of the particles in the complex Cu CMP chemistry can be helpful in explaining the experimental results in terms of MRR and surface finishing.
Persistent Photocurrent in InP Nanowires Heteroepitaxially Bridged Between Single Crystal Si Surfaces
Authors: Sarkar Ataur , Islam M. Saif , Yi Sungsoo , Talin A. Alec 
Published: April 2011

ABSTRACTRoom temperature photoelectrical characterization with 325-nm ultraviolet and 633-nm visible laser excitations is performed on lateral p-type InP nanowires bridged between vertically oriented heavily p-doped single crystal silicon electrodes. Experimental results under 5 V bias demonstrate persistent photoconductivity through a slow decay of excess photocurrent with relaxation times ∼110 s and ∼50 s for the UV and visible laser illuminations, respectively. Persistent photocurrent originates from the long recombination time due to carrier trapping in vacancies, defect centers, and surface states in the InP nanowires. The study opens a new understanding of trap physics of nanowire heterostructures, a critical investigation for applications of these materials in photonic devices.