bluuebunny/crossref_metadata_2025_split huggingface dataset:
Viewport Influence on Optical Pyrometry and Deposition Process in Mocvd Vertical Rotating Disc Reactors
Authors: Prokopenko Anton , Gurary Alexander , Boguslavskiy Vadim , Ramer Jeffrey , Schurman Matthew 
Published: April 2011

AbstractOptical access to the wafer for the in-situ process monitoring and control is a requirement for the advanced MOCVD equipment. Depending on their location and design, viewports can affect the reactor flow dynamics and temperature distribution inside the growth chamber thus ultimately affecting the deposition process. Furthermore, deposition on the viewport can influence the accuracy of in-situ measurements.We have investigated viewport influence on the MOCVD vertical rotating disc reactors manufactured by EMCORE Corporation. Viewport transmittance was established for different conditions and viewport types. Computational fluid dynamics was utilized to establish conditions at which viewport has no considerable influence on deposition results. The validity of model predictions was verified by examining the results of actual deposition runs on the reactor. We have demonstrated that under typical EMCORE reactor operating conditions, viewports presence on the reactor inlet flange and a purge flow through it have minimal effect on the reactor flow dynamics and ultimately on material growth rate and thickness uniformity.
Optical Integrated Waveguides Characterization by Scanning Near Field Optical Microscope
Authors: Borrisé X. , Barniol N. , Pérez-Murano F. , Abadal G. , Aymerich X. , Jiménez D. 
Published: April 2011

AbstractIn this work, we present (i) the development of a scanning near-field optical microscope (SNOM) for the characterization of optical integrated devices and (ii) the description of a new lithographic technique for the modification of standard integrated optical waveguides. SNOM images of rib waveguides allow to characterise the distribution of the guided modes for up to 1 mm of propagation distance. Some of the characterised waveguides present a periodical modulation of the light in the direction of propagation which is attributed to the Tien effect. In addition, we have performed high resolution modifications on the rib waveguide with an atomic force microscope combined with standard microelectronics processes. We demonstrate that the combination of this new lithographic technique with SNOM characterization allows to obtain new information about the propagation of the light in low dimensional structures.
Light-Excitation-Based Spectroscopy of Electronic Defects in Novel Materials
Authors: Castaldini A. , Cavallini A. , Polenta L. 
Published: April 2011

AbstractIn recent years several spectroscopic methods based on deep level photoionization have been developed because of the demand to investigate materials spreading over a wide range of resistivities. This paper deals with some capacitance- and current-based analyses, that are mature techniques for the characterization of semiconducting as well as semi-insulating materials with respect of deep level identification as well as spatial distribution. Results relevant to novel materials are also reported.
Low Temperature Photoluminescence and Photoinduced Current Spectroscopy on CdZnTe Grown by High-Pressure Bridgman Technique
Authors: Zerrai A. , Cherkaoui K. , Mergui S. , Zumbiehl A. , Hage-Ali M. , Marrakchi G. , Brémond G. 
Published: April 2011

AbstractLow temperature photoluminescence (PL), photoinduced current spectroscopy (PICTS) and thermoelectric effect spectroscopy (TEES) measurements have been carried out on several CdZnTe samples, taken from the same ingot, grown by the High Pressure Bridgman Technique. The PL bandgap edge luminescence allowed us to study the quality of the CdZnTe material. We have also determined the zinc segregation through the ingot. A broad luminescence band at lower energies was observed and correlated with PICTS results. The behavior of the defects through the ingot was studied by PICTS. Finally, these results are used to implement the resistivity model.
A Study of the Origin of Band-A Emission in Homoepitaxial Diamond Thin Films
Authors: Takeuchi Daisuke , Watanabe Hideyuki , Yamanaka Sadanori , Okushi Hideyo , Kajimura Koji , Sawada Hidetaka , Ichinose Hideki , Sekiguchi Takashi 
Published: April 2011

AbstractThe band-A emission (around 2.8 eV) observed in high quality (device-grade) homoepitaxial diamond films grown by microwave-plasma chemical vapor deposition (CVD) was studied by means of scanning cathodoluminescence spectroscopy and high-resolution transmission electron microscopy. Recent progress in our study on homoepitaxial diamond films was obtained through the low CH4/H2 conditions by CVD. These showed atomically flat surfaces and the excitonic emission at room temperature, while the band-A emission (2.95 eV) decreased. Using these samples, we found that the band-A emission only appeared at unepitaxial crystallites (UC) sites, while other flat surface parts still showed the excitonic emission. High-resolution transmission electron microscopy revealed that there were grain boundaries which contained π-bonds in UC. This indicates that one of the origin of the band-A emission in diamond films is attributed to π bonds of grain boundaries.
Spectrally Resolved Cathodoluminescence Determination of Dopant Diffusion In InP/InGaAsP Based Multi Quantum Well Fabry-Perot Lasers
Authors: Zanotti-Fregonara C. , Ferrari C. , Lazzarini L. , Salviati G. , Meliga M. , Bertone D. , Fang R. Y. , Morello G. , Paoletti R. 
Published: April 2011

AbstractLow temperature monochromatic cathodoluminescence (CL) spectral analyses and imaging were used to determine the widths of resistive regions (due to Fe diffusion) in multi-quantum-well (MQW) InP-based laser devices and to detect the different amount of damage induced by alternative In-situ Etching (ISE) and Reactive Ion Etching (RIE) techniques. The widths of the resistive regions were estimated by comparing the 5 K CL emission width from the MQW and the actual width as obtained by SEM investigations. Monochromatic CL also did not reveal any emission from the InP:Sn layer between semi-insulating material (Fe-doped lnp) and p-type layer (Zn-doped InP), indicating interdiffusion of Fe and Zn laterally the MQW, and the presence of substantial Sn diffusion (up to 2500 nanometers) into the substrate.
x-ray Surface Scattering Studies of Molecular Ordering at Liquid-Liquid Interfaces
Authors: Schlossman Mark L. , Li Ming , Mitrinovic Dragoslav M. , Tikhonov Aleksey M. 
Published: April 2011

ABSTRACTWe present our recent progress in using synchrotron x-ray surface scattering techniques to study several different aspects of ordering at liquid-liquid interfaces. (1) We present measurements of the interfacial width at the water-alkane interface for a series of different chain length alkanes. The width for the shortest chain length studied is in agreement with capillary wave theory. However, significant deviations occur for longer chain lengths, indicating the presence of molecular ordering at the interface. (2) Under appropriate conditions, a surfactant monolayer forms at the interface between water and a hexane solution of a fluorinated surfactant. Reflectivity measurements that probe the electron density profile normal to the interface provide information about the surfactant ordering. This monolayer undergoes a solid to gas transition as a function of temperature. Diffuse scattering near the transition reveals the presence of islands. (3) Equilibrium interfaces between two aqueous phases containing PEG (polyethylene glycol) and potassium phosphate salts can be studied. We present studies of coherent capillary wave fluctuations between two interfaces of a thin film of this biphase system. We also demonstrate that biological macromolecules can be trapped and studied at this aqueous-aqueous interface.
The Incorporation of Lung Surfactant Specific Protein SP-B Into Lipid Monolayers at the Air-Fluid Interface: A Grazing Incidence x-ray Diffraction Study
Authors: Lee K.Y.C. , Majewski J. , Kuhl T.L. , Howes P.B. , Kjaer K. , Lipp M.M. , Waring A.J. , Zasadzinski J.A. , Smith G.S. 
Published: April 2011

ABSTRACTGrazing incidence x-ray diffraction (GIXD) measurements were performed to determine the effects of SP-B1.25, the N-terminus peptide of lung surfactant specific protein SP-B1.25, on the structure of palmitic acid (PA) monolayers. In-plane diffraction shows that the peptide fluidizes a portion of the monolayer, but does not affect the packing of the residual ordered phase. This implies that the peptide resides in the disordered phase, and that the ordered phase is essentially pure lipid. The quantitative insights afforded by this study lead to a better understanding of the lipid/protein interactions found in lung surfactant systems.
Synchrotron x-ray Scattering Study on Oxidation of AIN/Sapphire
Authors: Kang H. C. , Seo S. H. , Noh D. Y. 
Published: April 2011

ABSTRACTWe present an x-ray scattering study of the oxidation of AIN/sapphire films into λ-A12O3 upon annealing. Epitaxial AIN/Sapphire(0001) transforms into nano-crystalline epitaxial λ-A12O3 during annealing at temperatures above 800°C in air. The crystalline orientational relation between the λ-Al2O3 and AIN are < 111 > // < 0001 > in the film normal direction, and < 110 > // < 1120 > in the film plane direction. The domain size of the spinel λ-A1203 crystalline is smaller than 50 Å in both out-of-plane and in-plane directions. The XPS depth profiles of the oxide film showed that the film is composed of aluminum and oxygen, and the atomic concentration ratio is about 2:3.
Study of the Buried Interface Behavior of Liquid Crystal Thin Films Using Synchrotron Radiation and Grazing Incidence x-ray Scattering Mode
Authors: Hu Y. , Martínez-Miranda L.J. 
Published: April 2011

ABSTRACTWe have used the intensity and tunability of a synchrotron x-ray source in order to access the buried interface between a glass substrate and a liquid crystal thin film. We find that for energy of 9.4kev, the x-rays can penetrate a 0.22mm substrate. Grazing Incidence x-ray Scattering has been used to study the alignment of the films as a function of depth and temperature. Our results indicate the presence of both a chevron structure and a structure similar to the helical twist-grainboundary (TGB) phase. Some films have a disordered interfacial layer. This technique can be applied in the study of semiconductor devices as well as surfactant film interfaces.
Investigation of Inhomogeneous In-Plane Strain Relaxation in Si/SiGe Quantum Wires by High Resolution x-ray Diffraction
Authors: Zhuang Y. , Schelling C. , Roch T. , Daniel A. , Schäffler F. , Bauer G. , Grenzer J. , Pietsch U. , Senz S. 
Published: April 2011

ABSTRACTThe structural properties of Si/SiGe quantum wires, which were grown by local solid source molecular beam epitaxy through a Si3N4/SiO2 wire-like shadow mask, were investigated by means of high resolution x-ray coplanar and x-ray grazing incidence diffraction, as well as by transmission electron microscopy. High resolution x-ray coplanar diffraction was used to obtain the average in-plane strain in Si/SiGe wires before and after removing the Si3N4/SiO2 shadow mask. x-ray grazing incidence diffraction measurements were performed to obtain information on the shape of the wires and on the depth-dependent strain relaxation. A finite element method was used to calculate the strain distribution in the Si/SiGe wires and in the Si substrate which clearly show the influence of the Si3N4/SiO2 shadow masks on the strain status of the Si/SiGe wires in agreement with the experimental data.
A High-Resolution Angle-Resolved Photoemission Study of the Temperature Dependent Electronic Structure of the Pentatelluride ZrTe5
Authors: McIlroy D. N. , Zhang Daqing , Kempton Bradley , Wharton J. , Littleton R. T. , Tritt T. M. , Olson C. G. 
Published: April 2011

ABSTRACTThe temperature dependent band structure of the pentatelluride ZrTe5 has been examined using the technique of high-resolution angle-resolved photoemission in conjunction with synchrotron radiation. Specifically, the band dispersion along the X-Γ-X high symmetry axis was mapped at 20K (T<Tc) and 170K (T>Tc), where Tc≃160K. One electron band and two hole bands within 0.5eV of the Fermi level have been identified. The dispersion of the bands indicates that they have extremely small electron and hole effective masses. The hole bands were observed to distort and shift in energy upon raising the sample temperature above Tc, indicative of a surface distortion.
The Role of Structure-to-Property-Relationships in Materials Characterization
Authors: Morgner W. 
Published: April 2011

ABSTRACTThe paper deals with questions concerning the material characterization for steels in the field of engineering and metallurgy. Based on the structure-to-property-relationships, a procedure is proposed to strengthen the systematical development of methods for nondestructive characterization of materials. The state of the nondestructive characterization of metals is reviewed and applications are described in which adequate macroscopic physical properties are measured in order to characterize the materials state and properties nondestructively. The materials characterization of ball bearing steel and cast iron using multiparametrical approaches is discussed in detail.
Microscopic Techniques for Characterization of Magnetic Layers
Authors: Meyendorf N. , Altpeter I. , Netzelmann U. , Hoffmann J. , Nichtlpecher W. , Grimm H. 
Published: April 2011

ABSTRACTIn recent years increasing interest in magnetic materials especially amorphous and nano crystalline layers has arised. Due to the magnetostrictive and magnetoresistive properties magnetic materials obtained high importance in sensor, actuator and memory applications. Therefore new methods to characterize magnetic and mechanical properties of magnetic materials are required. Two new microscopic techniques will be presented in this paper.
Three-Dimensional, Nondestructive Imaging of Low Density Materials
Authors: Kinney J.H. , Haupt D.L. , Lemay J.D. 
Published: April 2011

ABSTRACTThe goal of this study was to develop a three–dimensional imaging method for studies of deformation in low-density materials during loading, and to implement finite element solutions of the elastic equations based on the images. Specimens of silica–reinforced polysiloxane foam pads, 15 mm in diameter by 1 mm thick, were used for this study. The nominal pore density was 50%, and the pores approximated interconnected spheres. The specimens were imaged with microtomography at ∼16µm resolution. A rotating stage with micrometer driven compression allowed imaging of the foams during deformation with precise registration of the images. A finite element mesh, generated from the image voxels, was used to calculate the mechanical properties of the structure, and the results were compared with conventional mechanical testing. The foam exhibited significant nonlinear behavior with compressive loading. The finite-element calculations from the images, which were in excellent agreement with experimental data, suggested that nonlinear behavior in the load displacement curves arises from buckling of the cell walls during compression and not from any nonlinear properties of the base elastomer. High–resolution microtomography, coupled with efficient finite–element modeling, shows promise for improving our understanding of the deformation behavior of cellular materials.
IR Tomography of the Lifetime and Diffusion Length of Charge Carriers in Semiconductor Silicon Ingots
Authors: Akhmetov V.D. , Fateev N.V. 
Published: April 2011

ABSTRACTA nondestructive method for estimating quality of single-crystal Si ingots is proposed. The method provides a three-dimensional pattern of the lifetime and diffusion length of charge carriers inside Si ingots up to 300 mm in diameter and I m in length. The method employs optical probing of ingots with laser-emitted radiation and includes laser-induced photoinjection of charge carriers followed by laser-assisted monitoring of their spatial distributions and time evolution in any part of the ingot about 1 cm in size.
Small Signal AC-Surface Photovoltage Technique for Non-Contact Monitoring of Near Surface Doping and Recombination-Generation in the Depletion Layer
Authors: Marinskiy D. , Lagowski J. , Wilson M. , Savtchouk A. , Jastrzebski L. , DeBusk D. 
Published: April 2011

ABSTRACTSmall signal non-contact ac-SPV method for monitoring near surface doping (NSD) in silicon has recently been introduced in commercial diagnostic tools. High chopping frequency light with a submicron penetration depth is used to generate small SPV signal and this signal is in turn monitored using a transparent pickup electrode. This technique has the advantage of producing fast, non-destructive full wafer measurement. Under certain conditions, the magnitude of this ac-SPV signal is inversely proportional to the depletion layer capacitance. If a depletion layer barrier height is known this allows the calculation of the concentration of ionized donors or acceptors in the depletion layer. NSD measurements by ac-SPV method were typically done for doping concentrations up to about 1016 cm−3. Only recently this range has been extended to 1018 cm−3, making it a very attractive technique for monitoring low and medium dose implants and especially for wafer scale mapping of implant uniformity and activation efficiency. In addition, the frequency dependence of the SPV signal provides a mean for evaluating the minority carrier lifetime in the near surface region of bulk and epitaxial wafers.The influence of surface/interface traps upon small ac-SPV signal has never been fully understood. This paper quantifies the role of interface traps in the monitoring of NSD. The effect of typical surface treatments such as HF, SCI and SCI+SC2 wafer cleans are examined.
Image-Guided Failure Assessment of Porous Materials
Authors: Tantillo M. , Müller R. 
Published: April 2011

ABSTRACTLightweight metallic cellular materials have the potential for use in composite structures such as plates, shells, and tubes. In order to evaluate the usefulness of these porous materials, an understanding of their failure mechanisms is essential. We have developed a technique called image-guided failure assessment that allows for the 3-dimensional analysis of fracture initiation and progression on the microscopic level. The technique has already been used to study trabecular bone failure, and the objective of this study was to use the technique to study porous aluminum alloys. Image-guided assessment involves the use of a novel micro-compression device to apply and maintain loads, and the use of micro-computed tomography, providing 68 µm isotropic resolution in this application, to image the specimens. Specimens were compressed and imaged at intervals of increasing strain (0%, 0.8%, 4%, 8%, 16%, and 32% strain). The advantage of using a nondestructive approach to assess failure is that subsequent images of increasing strain can be animated to give visual information regarding fracture initiation and progression. In our tests, damage was seen to accumulate and propagate in local bands rather than being evenly distributed throughout the structure. This implies that local strains may be much larger than the apparent strain. These preliminary results demonstrate the usefulness of image-guided failure assessment in obtaining both visual and mechanical data regarding fracture initiation and progression. The technique is applicable to a multitude of porous materials and might, in the future, become a new standard in the mechanical assessment of these structures.
Nondestructive Measurement of In-Plane Residual Stress in Silicon Strips
Authors: Zheng Tieyu , Danyluk Steven 
Published: April 2011

ABSTRACTThis paper reports the development of a shadow moiré technique to measure the in-plane residual stresses of thin, flat strips. This is an extension of prior work on the measurement of in-plane residual stresses in silicon plates and wafers. Phase stepping shadow moir6 and digital image processing techniques are employed to measure the deflections of the silicon plate specimens subjected to three-point-bending at several different loads. The measured deflections over the area of the silicon plates are fitted with an equation represented by a 2-D polynomial. With the theory of thin plates with large deflection, the fitting coefficients are used to extract the in-plane stresses at the different bending load. The residual stress is resolved by linear regression of the in-plane stresses versus bending loads.
Interfacial Diffusion in a MOCVD Grown Barium Titanate Film
Authors: Datta A. , Chattopadhyay Soma , Richter A.G. , Kmetko J. , Lee C. B. 
Published: April 2011

ABSTRACTA combination of two nondestructive techniques, Grazing Incidence X-ray Reflectivity and High Resolution X-ray Diffraction, is used to study (at around 10Å resolution) the composition profile across a 500Å thick film of BaTiO3 grown epitaxially on (100) MgO by MOCVD. Results from both studies indicate diffusion of Mg to about 250Å into the film at film-substrate interface, consistent with the diffuse ferroelectric phase transition observed in this film. The lattice parameter a shows a progressive decrease as we move into the film from the interface, and an anomalously low value in the Mg-free portion of the film.
Impedance Spectroscopy Investigation on the Low-Temperature Degradation of Tetragonal Zirconia: Influence of Measurement Conditions
Authors: Santos A. P. , Domingues R. Z. 
Published: April 2011

ABSTRACTImpedance spectroscopy has been used for the characterization the low-temperature degradation of yttria-stabilized tetragonal zirconia polycrystals in a non-destructive assay. Superficial transformations resulting from annealing in air lead to the appearance of an extra relaxation in the impedance spectra which evolves with degradation extent. It has been demonstrated that in situ electrical characterization cannot be performed because the electrode layers retard the degradation phenomenon. The ideal temperature/time condition to record spectra is also discussed.
A Study of Quasi-Breakdown Mechanism in Ultrathin Gate Oxide Under Various Types of Stress
Authors: Guan Hao , Xu Zhen , Cho Byung Jin , Li M. F. , He Y. D. 
Published: April 2011

ABSTRACTThe quasi-breakdown (QB) in ultra thin gate oxide is investigated through the observation of defect generation during high field F-N stress and substrate hot hole and hot electron stresses. The interface trap density increases during stress and reaches to a same critical amount at the onset point of QB regardless of stress current density and stressing carrier type. The experiments also show that hot carriers are much more effective to trigger QB than F-N electrons at the same current level. This can be ascribed to the fact that hot carrier has much higher interface state generation rate than F-N electron does. All results consistently support the interface damage model for the QB occurrence.