bluuebunny/crossref_metadata_2025 huggingface dataset:
Deep Level Energy Analysis of Surface and Bulk Defects Using a Noncontact Laser/Microwave Photoconductance Technique
Authors: Buczkowski A. , Rozgonyi G. A. , Shimura F.
Published: March 2011

A noncontact technique for deep level energy analysis has been discussed based on a laser excitation/microwave reflection transient photoconductance procedure. An algorithm for separation of surface and bulk recombination effects was developed to independently determinesurface and bulk energy states. Deep energy levels associated with trapping and recombination processes have been calculated from the temperature dependence of surface recombination velocity and bulk recombination lifetime, based on state occupation statistics. Results have been compared with conventional DLTS data for silicon samples intentionally doped with metals during crystal growth.
Dynamic Operation of Quantum Well Seed's (Invited)
Authors: Chirovsky Leo M. F.
Published: March 2011

This paper describes methods of operating Quantum Well SEED's, which utilize the dynamic properties of the devices and thereby forego the need for optical bistability. The major advantages of dynamic operation versus the conventional modes utilizing optical bistability are that much less total optical energy is needed per cycle and/or much faster operation is possible due to much shorter switching times. Such dynamic modes of operation do require a more careful rationing of optical energy from external laser sources and require that the devices have much higher output contrast ratios.
Nondestructive Characterization of ZnSe/GaAs Heterostructure Using Transverse Acoustoelectric Voltage Spectroscopy
Authors: Han K. J. , Abbate A. , Bhat I. B. , Akram S. , Das P.
Published: March 2011

The electrical and optical properties of the heterostructure interface between high resistivity ZnSe and the semi-insulating GaAs substrate have been investigated using Transverse Acoustoelectric Voltage (TAV) spectroscopy. From the TAV spectra and the relative change of the TAV amplitude (ΔTAV/TAV), we have found the carrier type and concentration of ZnSe as well as the energy levels of various trap states at the heterostructure interface. The spectral behavior of the ΔTAV/TAV curves varied for samples of different ZnSe epilayer thickness. From the measurements, the surface recombination velocities (SRV's) were calculated. For the pseudomorphic ZnSe films on GaAs, a reduction in the SRV's was measured. As the thickness of the ZnSe film was increased, the various ΔTAV/TAV indicated presence of a large number of interface states due to the introduction of misfit dislocations.
Laser-Assisted Growth of ZnSe by Metalorganic Molecular Beam Epitaxy
Authors: Coronado C. A. , Ho E. , Kolodziejski L. A. , Huber C. A.
Published: March 2011

By employing metalorganic molecular beam epitaxy (MOMBE), the heteroepitaxy of ZnSe on GaAs has been achieved using diethylselenium and diethylzinc. Significant (10x ∼ 15x) growth rate enhancement has been observed when radiation from an argon ion laser is incident to the surface; photons with energies greater than the bandgap at the growth temperature contribute to the enhancement. Photo-thermal effects are ruled out due to the low power densities used (∼200 mW/cm2). Growth rate enhancementis found to be a function of substrate temperature, VI/II gas flow ratio, laser wavelength and intensity. To further understand the effect of the laser on ZnSe growth, solid sources of Zn and Se are used in conjunction with metalorganic gas sources. The effect of laser illumination is found to depend on the combination of precursors employed: both growth rate enhancement and growth rate suppression are observed. Laser-assisted growth has application for achieving. selective area epitaxy and for tuning the surface stoichiometry.
Relationship between Self-Texture and Interfacial Restriction on the Epitaxy of ZNO Thinfilms I
Authors: Fujimira Norifumi , Goto Seiki , Ito Taichiro
Published: March 2011

We investigated relationships between self-texture and interfacial restriction on the epitaxy of directed, bonded, thin films. Defect structures in ZnO films grown epitaxially on (0001)sapphire mere evaluated by 3—dimensional maping of k—spacing using an X—ray double crystal spectrometer. The orientation distribution and variation in lattice spacing of the films wre individually measured to elucidate the mechanism of growth. The growth mode was found to change at a film thickness of approximately 100 Å. The layer within 100Å of the interface had a small orientation distribution (1.8'), a large lattice spacing distribution, and a large cumpressive stress.The layer that was more than 100Å from the interface had a larger orientation distribution, a smaller lattice spacing distribution, and a smaller compressive stress.
In-Situ Characterization of AlGaAs Layers Grown by Chemical Beam Epitaxy Using Dynamic Optical Reflectivity
Authors: Armstrong John V. , Farrell Trevor
Published: March 2011

Characterization of A1GaAs layers grown in a VG-V80H chemical beam epitaxy chamber was achieved using dynamic optical reflectivity (DOR). The reflectivity for both stationary and rotating substrates was measured using a normal incidence visible laser. The DOR technique was used to measure the complex refractive index and the growth rate of the layer.The composition of the AlGaAs layer was then obtained from the published variation of refractive index with aluminum fraction. Using the refractive indices determined by DOR, good agreement with theory was achieved for the reflectivity trace from a AlGaAss/GaAs superlattice structure.
Epitaxial YSi2−x and ErSi2−x Thin Films on (111) Silicon
Authors: Lee T.L. , Su W.D. , Chen L.J.
Published: March 2011

Epitaxial RSi2−x (R = Y and Er) has been grown on (111)Si by solid phase epitaxy in ultrahigh vacuum deposited metal thin films on silicon. The evolution of vacancy ordering and defect structure in epitaxial YSi2−x. and ErS2−x thin films on (111)Si have been studied by both conventional and high resolution transmission electron microscopy.

Superlattice spots located at ⅓{2110} in [0001]RS2−x, diffraction patterns are attributed to the formation of ordered vacancy structure in the Si sublattice planes. The splitting of extra diffraction spots is correlated to the formation of an out-of-step structure. Streaking of the split diffraction spots in the diffraction pattern is attributed to the presence of an out-of-step structure with a range of M values. The M was found to settle down to a fixed value after high temperature and/or long time annealing.

Planar defects in RSi2™x films were analyzed to be stacking faults on {1010} planes with ⅙<1213> displacement vectors. Computer simulation was carried out to model the atomic structure of stacking fault in YS2−x-. thin films. The simulated images are seen to match rather well with experimental images taken under two different values of defocus.
Formation of The Interface between InP and Arsenic Based Alloys by Chemical Beam Epitaxy
Authors: Tamargo M. C. , Brasil M.J.S.P. , Nahory R. E. , Aspnes D. E. , Philips B. , Hwang D. M. , Schwarz S. A. , Quinn W. E.
Published: March 2011

We investigate the formation of inAs-rich layers at the interface between InP and arsenicbased Ill-V alloys grown by chemical beam epitaxy (CBE). In-situ spectroscopic ellipsometry, low temperature photoluminescence, secondary ion mass spectrometry and transmission electron microscopy were used to characterize the formation of these layers. We present evidence for interfacial layer roughness that depends strongly on growth temperature and on the presence of surface steps, and show that modifications of the interface chemistry and of the gas-switching sequence can reduce interfacial layer thicknesses.
Van Der Waals Epitaxy of GaSe on WSe2
Authors: Lang O. , Schlaf R. , Tomm Y. , Pettenkofer C. , Jaegermann W.
Published: March 2011

GaSe layers were grown on the van der Waals (0001) planes of WSe2 (van der Waals epitaxy). The substrate (0001) plane was cleaned in UHV by heating to 400°C. GaSe was deposited from resistively heated Knudsen cells at T=300° C. After annealing at 450°C an epitaxial GaSe overlayer is formed as evidenced by X-ray diffraction, scanning tunneling microscopy, low energy electron diffraction and photoelectron spectroscopy.
Atomic Processes in Silicon Hetero-Epitaxy
Authors: Venables J.A. , Drucker J.S. , Raynerd G.
Published: March 2011

The growth of metals and semiconductors on reconstructed semiconductor surfaces proceeds through a number of conceptually distinct stages. These include: 1) the growth of the first layer or layers, which may have different reconstructions as growth proceeds; 2) the growth of (2D or 3D) islands of the deposit, and/or by step flow; 3) coalescence and/or coarsening of islands and/or the introduction of defects such as dislocations. Of particular interest are cases when the different ‘stages’ are in competition with each other, i.e. they constitute alternative sinks for (and sources of) arriving and migrating adatoms. The development of rate equations to describe such situations, and extract relevant atomic parameters, is outlined. Experimental examples are taken from recent work on Ag and Ge deposits on Si( 111) and (100) surfaces.
Real-Time Femtosecond Ellipsometry of SixGe1−x Epilayers
Authors: Choo H. R. , Downer M. C. , Kesan V. P.
Published: March 2011

We have developed a femtosecond ellipsometer by incorporating ellipsometric probe optics into a rapid scan femtosecond pump-and-probe experiment. The system allows near real-time display of the photo-induced reflectivity changes and provides complete characterization of the time-varying dielectric function. This ellipsometer is used ex situ to characterize the femtosecond response of relaxed, MBE-grown SixGe1−x alloys over the complete composition range. The results show. that the femtosecond response depends strongly on alloy composition in optically thick samples. Ge-like samples (x<0.37) show a characteristic two-component response which may be caused by intervalley L →Γ hole scattering and impact ionization. For a given alloy composition, the presence of interfacial strain or surface oxidation strongly alter the femtosecond response.
Crystal Structures of Epitaxially Grown Fe16N2 Single Crystal Films with Giant Magnetic Moments
Authors: Komuro Matahiro , Hoshiya Hiroyuki , Takahashi Hiroaki , Mitsuoka Katsuya , Sugita Yutaka
Published: March 2011

Lattice parameters and crystal orientation for Fe1 6.N2 were determined by an X-ray diffraction method using a three axes goniometer. The lattice parameters of the a-axis and c-axis(a0, c0.) are 5.71 !A and 6.33 !A, respectively. The co corresponds to that of In0, 2,Gao.,s As substrates. Crystal orientation between Fe1 5.N2. films and Ino.,2Gao.,8 As is Fe1 0N2(001)//In0 2.Ga0.2 As(1001) and Fe1 0.N2.(100)//In02Ga0.6As(100). Intensity ratios for these diffraction peaks are in good agreement with calculated values proposed by Jack.
Molecular Beam Epitaxy Study of InAs/GaSb Heteroepitaxy on The (111)A and (111)B Orientations
Authors: Dura J. A. , Zborowski J. T. , Golding T. D.
Published: March 2011

We have investigated the molecular beam epitaxial growth of homoepitaxial InAs and GaSb and InAs/GaSb heterostructures on both the (111)A and (111)B orientations. Our studies have found that high quality GaSb epilayers can be grown on both the (111)A and (111l)B orientations over a wide range of growth temperatures and flux ratios. Reflection high energy electron diffr-action phase diagrams for GaSb [111[ are presented. InAs/GaSb heterostructures, simultaneously grown on (11l)A and (111)B orientations, have been investigated by secondary ion mass spectroscopy depth profiles and double crystal x-ray diffraction. Unintentional incorporation of the ‘second’ group-V element is found to be approximately three times greater in the (111)A orientation than in the (111)B for both species.
Near Bandgap Optical Absorption Measurements on InGaAs/InP Strained Layers with Coarse Structure
Authors: Roura P. , Bosch J. , Cornet A. , Peiroi F. , Morante J.R. , Clark S. A. , Williams R.H.
Published: March 2011

Optical absorption measurements have been carried out on compressive InGaAs/FInP strained layers. It is shown that thoptical absorption analysis is a powerful technique in order to study the inhomogeneities of strained layers. The energetic dispersion of the heavy hole relative to the light hole subband σHH/σLH is related with the presence of the coarse structure seen in Transmission Electron Microscopy observations.
“Barrierless” Misfit Dislocation Nucleation in SiGe/Si Strained Layer Epitaxy
Authors: Perovic D.D. , Houghton D.C.
Published: March 2011

The study of the critical thickness/strain phenomenon inherent in metastable, layered heterostructures has led to the development of several models which describe elastic strain relaxation. Hitherto, the nucleation of misfit dislocations required for coherency breakdown is the least well understood aspect of strain relaxation, due to the paucity of experimental data. Moreover, existing theoretical calculations predict relatively large activation energy barriers (>10 eV) for misfit dislocation nucleation in relatively low misfit (<2%) systems. In this work it will be shown that the nucleation of misfit dislocations can occur spontaneously demonstrating a vanishingly small activation energy barrier. Specifically, experimental studies of a wide range of GexSi1−x/Si (x< 0.5) hetero-structures, grown by MBE and CVD techniques, have provided quantitative data from bulk specimens on the observed misfit dislocation nucleation rate and activation energy using large-area diagnostic techniques (eg. chemical etching/Nomarski microscopy). In parallel, the strained layer microstructure was studied in detail using crosssectional and plan-view electron microscopy in order to identify a new dislocation nucleation mechanism, the ‘double half-loop’ source. From the combined macroscopic and microscopic analyses, a theoretical treatment has been developed based on nucleation stress and energy criteria which predicts a “barrierless” nucleation process exists even at low misfits (< 1%). Accordingly, the observed misfit dislocation nucleation event has been found both experimentally and theoretically to be rate-controlled solely by Peierls barrier dependent, glide-activated processes with activation energies of ∼2 eV.
Scanning Tunneung Microscope Studies of Initial Epitaxial Growth of YBa2Cu3O7-δ Thin Films
Authors: Zheng Xiang-Yang , Lowndes D. H. , Zhu Shen , Warmack R. J.
Published: March 2011

The initial stages of epitaxial growth of laser ablated YBa2Cu3O7-δ (YBCO) thin films on (001) SrTiO3, LaAlO3, and MgO substrates, and on slightly miscut LaA1O3 and SrTiO3, have been studied with scanning tunneling microscopy (STM). Surface images show that the initial YBCO growth mode can be either of the Stranski- Krastanov or the Volmer-Weber type, depending on the film-substrate lattice mismatch and the growth temperature. A small substrate miscut angle is found to strongly influence the growth mode of YBCO films. Screw dislocation-mediated growth is suppressed, and films grown at 800°C on (001) LaAlO3 substrates with miscut angle of 2.0° along <100> or <110> directions were found to consist of tilted platelets that are epitaxially aligned with the substrate crystal lattice.
The Effect of Substrate Surface Orientation and Epilayer Thickness on Ingaas/Gaas Epilayer Tilt and Tilt Direction
Authors: Chang J.C.P. , Kavanagh K.L.
Published: March 2011

Epilayer tilt about an in-plane axis has been measured for a number of InGaAs/GaAs interfaces grown by solid source molecular beam epitaxy on (001) substrates cut nominally flat or cut 2 degrees towards the <010> or <111> direction. It is found that a much larger tilt develops in epilayers grown on off oriented wafers although a comparable degree of strain was relaxed. The tilt is a function of epilayer thickness for thicknesses exceeding a second critical thickness which we associate with the onset of relaxation by predominantly dislocation multiplication processes.
The Effect of The Initial Nucleation Temperature on The Misfit Dislocation Structure of InP-on-GaAs Heterostructures
Authors: Riesz Ferenc , Radnoczi G. , Pecz B. , Rakennus K. , Hakkarainen T. , Pesek A. , Lischka K.
Published: March 2011

The misfit dislocation structure of vicinal InP-on-GaAs heterostructures is studied by transmission electron microscopy (TEM). An island type growth is identified. The misfit stress is not fully relaxed at the interface. X-ray measurements on strain relaxation and epilayer misorientation are also reported, and the latter results are explained with the asymmetric introduction of 6Ø° dislocations at island edges. Comparing the results, it is concluded that x-ray data supply additional, although indirect, information on initial growth which is hardly detectable by TEM.
A Model of Surface Misorientation Occurring During MBE of GaAs:Be
Authors: Bessolov V.N. , Lebedev M.V.
Published: March 2011

An impurity adsorption model is proposed accounting for a distortion of the surface morphology of GaAs:Be epitaxial layers and an emergence of misoriented facets. According to the model, the morphology distortion occurs as the surface sublimation energy of the growing face drops down to zero because of adsorption of Be atoms at the layer surface. The model is in good agreement with available experimental data on the surface morphology distortion of GaAs:Be layers grown by MBE.
Low-Defect-Density Ge on Si for Large-Lattice-Mismatched Semiconductor Integration and Strain-Engineered Devices
Authors: Malta D.P. , Posthill J.B. , Enquist P.M. , Markunas R.J. , Humphreys T.P. , Parikh N.R.
Published: March 2011

Heteroepitaxial Ge layers were grown on vicinal Si(100) by molecular beam epitaxy (MBE) at substrate temperatures of 500°C and 900°C. The layers grown at 500°C were topographically smooth with planar interfaces and a typically high threading dislocation density at the surface (> 108cm−2). Layers grown at 900°C (nucleation at 500°C) showed smooth topography, an interface highly facetted on (111) planes and a dense network of dislocations that is well confined to the interfacial region. Etch pit density measurements indicated that defect densities at the surface were as low as 1 × 105cm−2. Biaxial tensile strains of 1.2 × l0−3 and 2.5 × l0−3 were measured by Raman spectroscopy for the 500°C and 900°C layers, respectively. RBS/channeling spectra supported crosssection TEM results indicating interfacial defect confinement in the layers grown at 900°C. A model describing thermal radiation absorption suggests that interfacial Ge melting occurred during the high temperature growths.
A Multiplication Mechanism for Misfit Dislocations
Authors: Capano Michael A.
Published: March 2011

A new mechanism which describes how misfit dislocations in epitaxial layers multiply is presented. This work demonstrates how a single threading dislocation can give rise to an array of dislocation sources, where each source generates a single dislocation loop perpendicular to the primary misfit dislocation. As a threading dislocation with pure screw character glides through an epilayer, certain processes occur which lead to the production of a single dislocation half-loop, and the regeneration of the original threading dislocation. The regenerated threading dislocation continues to propagate on its primary glide plane, which allows the process to repeat itself at some later time. The result of this sequential process is an array of half-loops perpendicular to the primary misfit dislocation. The shape and symmetry of the arrays also contains information regarding how the mechanism operates. The proposed mechanism is related to misfit dislocation arrays in a single Si0.87Ge0.13 layer on Si(001).
Initial Stages of Growth of Epitaxial InAs Films on InP Substrate
Authors: Sekhar K. S. Chandra , Ballal A. K. , Salamanca-Riba L. , Partin D. L.
Published: March 2011

In this work we investigate the initial stages of growth of heteroepitaxial films of InAs on semi-insulating InP substrates using MOCVD. Very thin films grown at different temperatures, Tn, were studied using TEM and SEM. The 3.2% lattice mismatch between InAs and InP causes strains that are partially accomodated by the generation of misfit dislocations at the interface. Our studies indicate that the deposited InAs nucleates in the form of islands which then grow and coalesce to form the film. Elemental mapping studies indicate that the area of substrate covered by the film is a function of the growth temperature. The thickness of the film and the electron mobilities also vary with T°. The films with best mobilities were obtained for Tn = 480°C.
Step-Driven Surface Segregation and Ordering During Si-Ge MBE Growth
Authors: Jesson D. E. , Pennycook S. J. , Baribeau J.-M. , Houghton D. C.
Published: March 2011

An important role of type SB step edges in determining the as-grown microstructure of Si-Ge superlattices and alloys is implicated from direct Z-contrast images of as-grown structures. A variety of different ordered phase variants can arise at each Si on Ge interface as a result of vertical segregation during superlattice growth. A new monoclinic-ordered structure is predicted to arise as a result of lateral segregation during alloy growth.
New Developments in Soluble Thermoplastic High Glass Transition Temperature Polyimides
Authors: Rogers M. E. , Moy T. M. , Kim Y. J. , McGrath J. E.
Published: March 2011

Utilizing solution imidization, molecular weight and end group control techniques, soluble, fully cyclized polyimides with very high glass transition temperatures have been developed to meet high temperature applications. Mechanistic aspects are investigated for solution imidization by both the polyamic acid route and by the ester-acid route. Polyimides based on pyromellitic dianhydride and a 3F diamine exhibit glass transition temperatures of 420 °C. These polyimides are soluble in polar aprotic solvents and form tough, transparent films which demonstrate mechanical integrity and thermooxidative stability at 700 °F. Various processing routes are explored to demonstrate the viability of these materials in high temperature applications. Details of the synthesis and characterization of these materials will be provided.
Mechanical Characterization and Constitutive Description of Thin-Film Polymeric Materials
Authors: Wu T. Y. , Questad D. L.
Published: March 2011

Mechanical properties of thin-film polymers often dictate the mechanical integrity and performance of microelectronic assemblies. For example, excessive interfacial stress between the polymer and signal via induced by thermal mismatch will lead to delamination of the interface or via cracking. This type of problem becomes more aggravated as dimensions of assemblies continue to shrink. In order to define the optimal design variables and process windows, the mechanical properties of polymer thin films throughout the complete process cycle must be carefully characterized. This paper will first review the experimental techniques commonly adopted in the mechanical measurements of thin-film polymers. Then, it will focus on the most difficult part of the mechanical characterization which is along the out-of-plane (Z) direction. Experimental set-up using the capacitance gauge will be introduced. Critical mechanical properties of polymers will be discussed. For the purpose of illustration, two polymers are chosen as examples. A BPDA-PDA polyimide is used to demonstrate mechanical characterization before melting whereas a PTFE-SiO2 composite is chosen to demonstrate the rheological characterization after melting. Before melting, mechanical behaviors such as the stress-strain curve, creep, relaxation, coefficient of thermal expansion, strain-rate dependence, and temperature dependence are discussed. After melting, the rheological behavior and the effect of aspect ratio measured by a squeezing flow experiment are addressed. Constitutive descriptions are proposed. The functional dependency between stress (pressure), strain (displacement), time, and temperature are characterized. A comparison between the numerical simulations and the experimental measurements is also presented.
Studies of PQ-100(TM) Polyquinoline Film for Multichip Module(MCM) Applications
Authors: Paik Kyung W. , Cole Herbert S. , Hendricks Neil H.
Published: March 2011

Oxygen and O2+CF4 RIE showed faster etch rate of PQ-100 film than nonoxygen containing RIE, and caused rough surface morphology. Ti shows good adhesion to the PQ-100 film because of Ti-O and possible Ti-N compound formation at the interface. No diffusion of Ti and Ti-containing precipitates were observed at the Ti/PQ interface even at temperatures of 250 °C. In contrast to the Ti/PQ interface, Cu showed very poor adhesion to the PQ film because of weak chemical bonding. Cu reaction compounds were not observed at the interface at the 250 °C annealing. Ti adhesion to the PQ-100 film was good for control, RIE modified, and water-boiled cases. Initial studies suggest a reduction in peel strength at 250 °C annealing, although this topic must be further addressed to understand the exact mechanism.
The Adhesion of Polymer-Polymer Interfaces
Authors: Brown Hugh R.
Published: March 2011

The adhesion of glassy or semicrystalline polymers to themselves or to other polymers is often poor. Polymers gain their strength from the mechanical interconnection between different chains. This interconnection can occur either by the use of long chains that entangle with each other or by chemically joining the chains by cross-linking. A strong polymer-polymer interface is crossed by many chains that are mechanically coupled into the material on both sides of the interface. For cross-linked systems these coupling chains must be cross-linked into both sides. If the polymers are not crosslinked, the coupling chains are formed by interdiffusion or welding. Interdiffusion can occur only if the system is heated to a temperature that allows significant chain mobility and if the interconnecting chains are sufficiently miscible in both polymers. For some systems, such as polyimides, the mobility required can either be generated by just part curing the materials before joining or by reversing the completed cure of a thin surface layer before joining and completing the cure. The interconnecting chains do not have to be the same material as the polymers being joined and, for joining dissimilar polymers, can be block copolymers where each block is miscible in just one of the relevant polymers.
Experimental Analysis of the Adhesion of Copper and Chromium Films Deposited on a Polymer
Authors: Ignat M. , Fayette L. , Normandon P. , Templier F. , Torres J.
Published: March 2011

An analysis of bulk and interfacial damage of film/substrate systems consisting of copper or chromium films deposited on a single polymer substrate, is presented here. For these systems (metal/single polymer substrate) the failure analysis is based on the experimental results obtained from deformation experiments performed in a scanning electron microscope. Critical parameters deduced from the experiments, and microstructural observations allow us to discuss the mechanical behaviour of these systems, and their interfacial adhesion properties.
A New Gold-Indium Eutectic Bonding Method
Authors: Lee Chin C. , Wang Chen Y. , Matijasevic Goran , Chan Steve S.
Published: March 2011

Au-In eutectic bonding method which needs only a low process temperature (˜200°C) but produces high temperature (450°C) bonds is reported. In this study, multiple layers of Au and In are deposited directly on semiconductor wafers in one vacuum cycle to prevent indium oxidation and then bonded to substrates coated with Au. At 200°C the indium layer melts and dissolves the gold layers to form a mixture of liquid and solid. The diffusion process continues until the bond solidifies. Upon solidification, the bond has a melting temperature of 456.5°C. Scanning Acoustic Microscope was used to determine the excellent bonding quality before and after thermal shock tests and SEM with EDX capability is employed to determine the composition of the resulting bonds.
Optical Interconnects and Interfaces for Electronic Subsystems
Authors: Rajasekharan K. , Krusius J.P. , Sutherland J. , George G.
Published: March 2011

The potential, feasibility, and time scale of optical interconnect and interfaces are examined for electronic computer applications. Link, bus and random interconnect topologies are included. Recent developments in optical source and detector devices, optical waveguides and optical fiber characteristics are reviewed. Then optical coupling, alignment, interfacing and overall compatibility issues are explored. From this understanding the requirements for the packaging of optical interconnect are derived. Finally key research and development needs are defined.
Polymer/Metal Interconnection Systems for Microelectronics Packaging
Authors: Tong Ho-Ming
Published: March 2011

This article provides an overview on polymer/metal interconnection systems for microelectronics packaging. It will begin with a description of the functions of interconnection, and types of polymer/metal interconnection techniques available with tape automated bonding (TAB) being the most popular for chip connection applications. This is followed by examples of worldwide TAB applications and market outlook, TAB tape offerings and trends, as well as the entire TAB technology including tape types and fabrication, substrates interconnected by TAB, bonding techniques, TAB mounting options and TAB package encapsulation. Finally, future challenges on the most demanding fine-pitch TAB technology will be discussed.
Polyimide for Multichip Modules: Materials and Process Challenges
Authors: Rucker T. , Murali V. , Shukla R. , Neuhaus H.
Published: March 2011

As the performance of desk-top systems approaches 100 Mhz there is a need to develop a packaging technology capable of supporting high speed chip to chip interconnections. Polyimide based multichip modules are excellent packaging solutions that have minimum propagation delays and are cost effective. This paper presents the material properties and processing issues that need to be addressed in building reliable modules. A cost effective and reliable packaging solution is described in detail.
Recycling of Wood and Paper in Cementitious Materials
Authors: Soroushian Parviz , Arola Rodger A. , Shah Zahir
Published: March 2011

Beneficial utilization of wastepaper and wood in cement-based materials is reviewed. Wastepaper presents a source of reinforcing fibers for thin-sheet cement products; these fibers help overcome the problems with the brittle nature of failure and low cracking resistance of plain cement products. Wood waste and sawdust can be used in concrete as light-weight aggregates capable of enhancing the weight-to-strength ratio, insulation properties and toughness characteristics of concrete materials.
The Basic Effects of Recycling on Pulp Properties
Authors: Howard R. C. , Bichard W.
Published: March 2011

Using standard laboratory procedures it was found that different pulp types showed very different recycling effects. Mechanical pulp fibres became flatter and more flexible giving a denser, stronger sheet. Beaten chemical pulp fibres “hornified”, resulting in a bulkier, weaker sheet. Unbeaten chemical pulp fibres were initially curly; recycling removed the curl. A mechanical/chemical pulp blend revealed that these effects occur at different rates. In no case was there evidence of fibre strength loss, or of fibre embrittlement. In these laboratory experiments, fines loss during sheetmaking affected the magnitude of the sheet properties, but not the trends.
Recycled Structural Papers: New Approaches for Material Property Improvement
Authors: Laufenberg Theodore L. , Hunt John F.
Published: March 2011

Recycling of fiber into structural papers for the corrugated container industry, paper tubes, cartonboard or other paperboard with structural performance needs may require enhancement of properties through changes in the papermaking process. The loss of bonding capability, coupled with a degree of fiber shortening and fiber inflexibility, reduces the utility of recycled fiber and thus their competitiveness with their virgin counterparts. Traditional means for enhancing performance includes addition of starches or other binders, mechanical beating, or heat treatments. Other means for achieving heightened performances are reviewed which include alternative drying technologies, optimal placement of fibers within the paper sheet and forming technologies that provide structural enhancement. KEYWORDS: Fibers. fractionation, swelling, drying methods, fiber bonding. fiber alignment, pulp molding.
Opportunities for Composites from Recycled Wood Based Resources
Authors: Wegner Theodore H. , Youngquist John A. , Rowell Roger M.
Published: March 2011

A reduction is urgently needed in the quantities of industrial and municipal solid waste materials that are currently being landfilled. Major components of municipal solid waste include waste wood, paper, agriculture wastes, and other biomass fibers. In 1990, there were approximately 80 million tons of 6,000 different paper and paperboard products and 5.8 million tons of wood in the municipal solid waste stream. There are also potential millions of tons of wood fiber in timber thinnings, industrial wood waste, demolition waste, pallets, and pulp mill sludges. These materials offer great opportunities as recycled ingredients in wood-based composites. This paper discusses possibilities for manufacturing selected composites from these materials as well as materials which coexist with the wood-based resources such as plastics, fly ash, and gypsum.
Fiber Based Composites from Recycled Mixed Paper and Magazine Stock
Authors: Rowell Roger M. , Harrison Sandra
Published: March 2011

For most products, processing recycled paper back into paper will require de-inking and removal of coatings and fillers. Paper to paper recycling will also require sorting the paper waste stream to insure that the stock used contains the type of fiber needed. These problems can be eliminated if the waste paper product stream is used to make fiber based composites. Mixed office waste, packaging materials, paperboard, newspaper, and many other types of paper fiber can be used directly for the production of thermosetting or thermoplastic fiber based composites. High levels of clay used in magazine paper can be tolerated in these composites. This paper will review research in making fiber based composites from several waste paper streams and the properties of these products.
Sulfate Formation During Corrosion of Copper Alloy Objects
Authors: McNeil Michael B. , Mohr D. W.
Published: March 2011

The copper sulfate minerals chalcanthite (CuSO4.5H20), antlerite (Cu3SO4(OH)4), and brochantite (Cu4SO4(OH)6) are observed as corrosion products on copper alloy objects such as statues which are exposed to weathering. The usual product in aqueous corrosion is brochantite, though posnjakite (Cu4SO4(OH)6H20) is also known. No copper sulfate mineral is commonly found in artifacts recovered from near-surface burial. These observations can be explained in terms of stability diagrams and microbiological activity.
Evaluation of Rapid Prototyping Technologies for Use in the Production of Art and Artifact Study Copies
Authors: Podany Jerry C.
Published: March 2011

Many artifacts and works of art are too fragile to be accurately replicated for scholarly study by using traditional methods of plaster or silicone molding techniques. In addition to the potential for loss of surface and fracturing, the use of many modern silicone mold materials may lead to irreversible staining of the original surface.

An evaluation of newly developed rapid prototyping technologies and their potential application to this problem was conducted by the J. Paul Getty Museum Department of Antiquities Conservation in conjunction with Laser Design Inc. of Minnesota and Hughes Aircraft Corp. of California.

Rapid prototyping technology allows accurate copies to be made without surface contact with the original object. This paper discusses the outcome of an initial investigation into one of these processes, stereolithography. A plaster model was submitted for laser scanning using a point laser probe, programmed for a 3.175 mm (0.125) distance between scan lines. The input was filtered and stored in an STL (stereolithography) format which provides the X,Y and Z coordinates of the A,B,C and normal vectors of a predetermined number of surface triangles. This data was then used to produce a three-dimensional copy.

Stereolithography produces hollow or solid threedimensional forms by feeding data that make up cross sectional slices of the object scanned to a focused laser aimed along the Z axis of the potential copy. The laser polymerizes the outer contour of the 'slice' in a thin layer of photopolymer deposited on a stage located below the laser. Following each slice production the stage lowers approximately 19 mm (0.75) below the surface of the liquid polymer reservoir and upon resurfacing positions approx 0.05mm (0.002) lower than its previous position. A “squeegee” gently crosses over the surface resulting in a thin film of polymer available for the production of the next cross section. The laser is then sent the next cross sectional data and the sequence of section building continues.

The specific challenge presented by this project was to assure that the surface detail of the copy formed presented acceptable fidelity to the original object (model), avoiding any need for follow up bench work or correction. The advantages, drawbacks and newly developed alternatives to this promising technology are discussed.
Monuments as Targets
Authors: Koscevic Zelimir
Published: March 2011

My paper is a video presentation, but before I show it, allow me just a few words. My contribution is not a scientific paper. In this video we shall be faced with the facts. Facts are always that starting point in the process of thinking, and thought is the basis of human activity. These facts are given concisely in 25 minutes, which is — frankly — nothing compared to the hours and hours I spent watching the raw documentary material, selecting it, and making the final version of the video that you are about to see.
Saving Grace: Can Cambodia's Ancient Site of Angkor be Preserved?
Authors: Garfield Donald
Published: March 2011

For 1,200 years Cambodia's historic royal complex of Angkor, one of the world's architectural wonders, has survived all threats from man and nature. But the greatest pressures on Angkor have come during the late 20th century, especially the devastation caused by more than two decades of war and civil strife. Now, with increased conservation and restoration efforts initiated by the World Monuments Fund and other international cultural institutions and coordinated by the United Nations Educational, Scientific and Cultural Organization (Unesco), three new threats have emerged. One is an increase in the looting of the sculptures and bas-reliefs decorating the sides of temples, galleries, and terraces. The second is the lack of a comprehensive, coordinated plan for conservation. The third, with potentially the most destructive results, is the uncontrolled development of the sacred site as a major tourist attraction.
Analysis of Materials Contained in Mid-4th to Early 7th Century A. D. Palestinian Kohl Tubes
Authors: Blanchard William D. , Stern E. Marianne , Stodulski Leon P.
Published: March 2011

The powdered contents of 17 Late Roman and Byzantine glass vessels used to hold cosmetic eye-paints (kohl) were analyzed. The principal analytical techniques employed were X-ray diffraction, Fourier-transform infrared spectrometry, X-ray fluorescence, and scanning electron microscopy. The materials detected are described, indicating those which may have been used as kohl. Also reported are analytical results from a solid chunk of material surrounding a fragment of a metal rod, also obtained from a kohl vessel.
Examination of Metal Threads From Some Xv/Xvi Century Italian Textiles by Scanning Electron Microscopy-Energy Dispersive X-Ray Spectrometry
Authors: Montegut D. , Adelson C. , Koestler R.J. , Indictor N.
Published: March 2011

Scanning electron microscopy and energy dispersive x-ray spectrometry (SEM-EDS) has been employed along with the light microscope to describe some metal threads taken from some late Medieval and Renaissance textiles attributed to Italy in the collection of the Metropolitan Museum of Art, New York. Comparisons are made within the group studied and to those descriptions of metal threads found in recent literature. The results are discussed in terms of geographic and historic markers of the metal thread technology employed.
Neutron Induced Autoradiography and Pixe Analysis
Authors: Taft W. Stanley , Mayer James W. , Aderhold Howard C. , Keller Matt , Rizzo Gia
Published: March 2011

We have used the TRIGA reactor and the Ion Beam Facility at Cornell to illustrate neutron induced autoradiography and PIXE analysis of known pigments in demonstration paintings made for our undergraduate course, ‘Art, Isotopes and Analysis’. A group of pigments were chosen containing elements with half-lives detectable by the neutron activation process. The pigments (suspended in a binding medium of linseed oil) were first painted on test swatches of acetate and their characteristic x-ray lines measured with a 5 Mev beam of protons directed through a thin Kapton film for external (in air) analysis (PIXE).

Three layers of images, each painted with a different pigment, overlay one another. The painting is then taken to the TRIGA reactor for neutron activation. After activation, the painting is placed in contact with sheets of Polaroid type AR positive transparency film at different times after exposure. The gamma spectra during the sequence are also measured to provide identification of the ‘active’ isotopes during each film exposure.
Forgery Determination by Functional Analysis
Authors: Gorelick Leonard , Gwinnett A.J.
Published: March 2011

Stone statuettes from turkey in simply shaped animal and bird forms were analyzed using scanning electron microscopy. observations made in drill holes in some of the artifacts led to definite unequivocal evidence for forgery while others were equivocal.
A General Method for Determining the Mechanical Properties Needed for the Computer Analysis of Polymeric Structures Subjected to Changes in Temperature and Relative Humidity
Authors: Mecklenburg Marion F. , Tumosa Charles S. , McCormick-Goodhart Mark H.
Published: March 2011

This study examines the methods for determining the effects of temperature and relative humidity (RH) on the dimensional and mechanical properties of artists' materials. Using both of these properties, typical cultural objects, such as paintings and photographs can be modeled on the computer to correlate the magnitude of developed stresses to environmental changes. Comparing these calculated stresses with the measured strength of the materials provides the opportunity to assess the potential risk from damage due to environmental change. Recognizing that the mechanical properties of polymeric materials are functions of the rate of the application of load, the time they are subjected to a load, the temperature and the relative humidity, it becomes a question of identifying those parameters that are the most important in determining the correct information needed for computer modeling.
Effects of Water on the Mechanical Properties of Paper and their Relationship to the Treatment of Paper
Authors: Vitale Timothy
Published: March 2011

Through a series of experiments the mechanical properties of paper are explored. Hydrogen bonding is fundamental to the performance of paper and its disruption results in distinctive stress-strain behavior. Stress-strain curves were generated from which tensile strength, Young's modulus, percent stretch, and work (tensile energy absorption) were obtained.

It was found that the contribution of the fiber to the mechanical properties of paper is primarily elastic. Fibers are many times stronger than paper. Only fibers which have been severely deteriorated show measurable changes in stress-strain behavior. Fiber deterioration results in characteristically different stress-strain behavior than that which results from disruption of interfiber bonding.

Water immersion results in the disruption of interfiber bonds in paper, leaving only 2-3% of dry tensile strength. Interfiber bonds make a profound contribution to the mechanical properties of the paper. Aqueous treatment is shown to be a radical treatment, altering the original dried-in properties of the sheet. The release of structural bonds and dried-in strains during wetting and the subsequent reformation of interfiber bonds during drying are shown to be independent of water purity, be it ultrapure water, tap water, or water containing washing aids such as Ca(OH)2, NaOH, CaCO3 or Na2CO3.

The effects of immersion in organic solvents was explored. Solvents have effects on mechanical properties which are approximately proportional to the degree of swelling caused by the solvent. Water, the liquid which caused the greatest swelling of the liquids evaluated, is shown to be the most disruptive liquid followed by methanol and acetone; toluene caused virtually no change.

To explore the behavior of interfiber bonds paper was taken through a solvent exchange process. A sample was immersed in water and then taken through separate ethanol and acetone immersions to toluene, and dried. The result was a sheet with little bonding and decreases in all mechanical properties. To explore the surface tension and capillary action effects of water, the solvent-exchanged sheet was re-immersed in water. Upon drying, interfiber bonding was reintroduced which resulted in the regain of mechanical properties lost.

A paradigm for the mechanical behavior of paper is developed. Fibers contribute elastic behavior and interfiber bonds are a principal source of plastic behavior.
Terracottas Around Clodion: Chemical and Mineralogical Studies and Thermoluminescence Analysis
Authors: Saltron Frédéric , Bouquillon Anne , Querré Guirec
Published: March 2011

Forty one terracottas by Clodion, Marin and P. Michel, all french sculptors of the XVIIIth century, have been analyzed in the L.R.M.F.

Two different kinds of analysis have been performed.

The results obtained by thermoluminescence allowed to partition the works between one group contemporaneous with the Clodion period and the other one consisting of posterior works. Although the lowest limit in the use of thermoluminescence seems to be reached, the conclusions are, more often than not, in agreement with the hypotheses of the curator.

X-Ray diffractometry, microprobe analysis and ion-beam methods (PIXE) have led to distinguish between siliceous pastes corresponding to artifacts created in Paris and carbonated pastes gathering terracottas made during the italian stays of the artists.
White Incrustation on Pottery From Neolithic Tell Samovodene, Bulgaria
Authors: Gencheva Julia
Published: March 2011

Twelve samples of lime plaster were examined, including a white incrustation on vessels and religious tables and the contents of a large vessel filled with the white substance. These materials are from Tell Samovodene, Bulgaria which was inhabited during the Neolithic period between 5750 and 5400 B.C. Crystal-optical analysis, X-ray diffraction, emission spectroscopy and scanning electron microscopy (SEM) were used in the analysis. It was established that the white contents of the vessel consisted of slaked lime which had been carbonized in antiquity. The white incrustation was shown to be a lime plaster, composed of slaked lime and quartz. We are continuing investigation of the kiln, found on the periphery of the tell; preliminary data suggest the kiln was used for lime burning.