bluuebunny/crossref_metadata_2025 huggingface dataset:
Zone Melting Recrystallization of Patterned Films and Low-Temperature Graphoepitaxy
Authors: Smith Henry I. , Thompson C.V. , Geis M.W. , Atwater H. , Yonehara T. , Wong C.C.
Published: March 2011

Zone melting recrystallization (ZMR) of Si films on SiO2 has produced large-area films with electrical properties approaching those of bulk wafers. The mechanisms of film formation and the use of patterning to control orientation and defect distribution are briefly reviewed. Some examples of the use of patterning are: single-grain films have been produced by means of planar constrictions; subboundaries and impurities have been entrained to lie along straight lines separated by ∼100μm through the use of lithographically defined grating patterns; a vertical-constriction technique has enabled (100) texture to be achieved in 50μm-thick Si films; a lithographically-defined orientation filter, which takes advantage of growth-velocity anisotropy, has been used to select a predetermined azimuthal orientation.

Patterning is also fundamental to graphoepitaxy. Current research emphasizes low temperature processes based on solid-state surface-energy-driven secondary grain growth.
Recrystallization of Polycrystalline Silicon Over SiO2 through Strip Electron Beam Irradiation
Authors: Hayafuji Y. , Yanada T. , Hayashi H. , Williams K. E. , Usui S. , Kawado S. , Shibata A. , Watanabe N. , Kikuchi M.
Published: March 2011

We have studied the influences of substrate orientation and growth direction on laterally seeded recrystallization of poly-crystalline silicon on a SiO2; film through strip electron beam irradiation. We found that growth in a [110] direction produced films with better crystal quality than growth in a [100] direction on a (001) substrate, and that growth in a [211] direction provides better crystal quality than growth in a [011] direction on a (111) substrate. A simple model of the growth interface composed of {111} planes is proposed
Soi Technologies at the CNET
Authors: group Soi
Published: March 2011

For the recrystallization of poly-Si films deposited on oxidized Si wafers, we focus our research on lamp and cw laser systems. We have obtained large single-crystal films using both techniques. “Selective annealing” allows localization of the remaining defects in the recrystallized films. Crystallographic as well as electrical characterization confirm the device-worthy potential of this material.
Nmos Logic Circuits in Laser-Crystallized Silicon on Quartz
Authors: Chiang A. , Zarzycki M. H. , Meuli W. P. , Johnson N. M.
Published: March 2011

Depletion mode as well as enhancement mode n-channel thin-film transistors (TFT's) have been fabricated in CO2 laser-crystallized silicon on fused quartz. Nearly defect-free islands were obtained by using an offset circular beam to form a tilted melt interface. The optimization of subsequent processing steps to achieve simultaneously low leakage currents and voltage thresholds appropriate for depletion-load NMOS circuits involved adjustments of ion implantation and high temperature cycles with the aid of simulation. The resultant high performance silicon-gate TFT's have led to NMOS ring oscillators with 2.5 ns delay/stage and dynamic shift registers with MHz clock rates. These are the first logic circuits fabricated in beam-crystallized silicon on bulk amorphous substrates.
Zone Melting Recrystallization of InSb Films on Oxidized Si Wafers
Authors: Wong C.C. , Keavney C.J. , Atwater H.A. , Thompson C.V. , Smith H.I.
Published: March 2011

InSb thin films on oxidized Si wafers have been recrystallized using a strip heater to generate and scan a narrow molten zone across the film. Grains up to 3 × 10 mm have been produced. Crystallization proceeds in a faceted cellular fashion, the excess solute (Sb) being rejected into subboundaries which often lie along low-index crystallographic directions. A InSb-Sb eutectic structure forms at the subboundaries. The width of the single-crystal InSb between subboundaries is approximately 75 μm. The techniques of planar constriction and subboundary entrainment have been extended to InSb for the selection of single grains and the orelocation of subboundaries. This technology of producing InSb thin films on oxidized Si substrates max, be extendable to other III-V materials, and could lead to novel device structures through the integration of Si and III-V compound devices on the same substrate.
Annealing of High Dose Implanted GaAs with Halogen Lamps
Authors: Nissim Y.I. , Joukoff B. , Sapriel J. , Henoc P.
Published: March 2011

Halogen lamps are used to anneal implanted GaAs. Surface protection is obtained by mouting the substrate in a sandwiched configuration between a silicon and a quartz plate. Raman scattering measurements are carried out to follow simultaneously lattice reconstruction and surface degradation due to Arsenic loss. The evolution of the Raman spectra is compared to a T.E.M. analysis carried out on the same samples.
Rapid Thermal Annealing of Ion Implanted GaAs and InP
Authors: Vaidyanathan K.V. , Dunlap H.L.
Published: March 2011

This paper discusses the properties of high intensity lamp-annealed silicon or beryllium-implanted GaAs and InP samples. We find this annealing process can result in efficient activation of dopants. Conventional furnace annealing at the same temperature does not result in increased electrical activation of the dopants. High fluence silicon implants can be activated in anneal times as short as 2 seconds, while low fluence silicon implants require more extended annealing. Activation of low fluence implants in GaAs depends strongly on the properties of the bulk semiinsulating material.
Study of Dielectric Caps for Incoherent Lamp Annealing of InP
Authors: Soda W.J. , Lorenzo J.P. , Davifs D.F. , Ryan T.X.
Published: March 2011

A parametric study is presented of CVD and RF sputter deposited SiO2 and PSG dielectric caps for incoherent lamp annealing of InP. Both deposition and annealing parameters are studied. We observe that CVD caps provide reliable mechanical protection during lamp annealing up to maximum bulk temperatures of 830°C, while sputtered deposited SiO2 caps perform well ,up to 850°C. We find however that sputter deposited caps introduce process related conduction into both unimplanted and implanted semi-insulating InP. Electrical activation of implanted dopants is also studied as a function of capping technioue. Lamp annealing of InP protected by caps with CVD phosphorus doped SiO2 in contact with the InP surface, results in excellent activation efficiencies in Si+ implanted material. When properly capped and annealed, we observe electrical profiles whose shape more nearly approaches theoretical LSS, than those previously reported.
Dopant Redistribution in Titanium Silicide/n+ Polysilicon Bilayers During Rapid Thermal Processing
Authors: Cooper C. B. , Powell R. A. , Chow R.
Published: March 2011

The successful use of rapid thermal processing in an isothermal mode to form Ti polycide structures is described. The silicide was sputter deposited from a composite Ti-Si target onto phosphorus-doped poly-Si. The resulting polycide structure was annealed by exposure to the blackbody radiation from a resistively-heated graphite heater. Rapid diffusion of the P into the Ti silicide is observed even for short annealing times, although resulting P concentrations in the silicide (>7 × 1018cm−3) are relatively low, about 100 times lower than in the doped poly-Si. Properly chosen RTP parameters can minimize the sheet resistance of the polycide without increasing the sheet resistance of the underlying poly-Si layer, which has not been possible for furnace-annealed samples.
Energy-Beam Processing Studies on Ta/U and Ir/Ta Systems
Authors: Kaufmann E. N. , Peercy P. S. , Jacobson D. C. , Draper C. W. , Huegel F. J. , Echer C. J. , Makowiecki D. M. , Balser J. D.
Published: March 2011

Films of Ta metal on uranium and of Ir metal on tantalum have been irradiated and melted by pulses from Q-switched Ruby and frequency-doubled Nd:YAG lasers to investigate the nature of the resulting mixtures in light of the very different binary-phase diagrams of the two systems. In addition, a two-phase Ir-Ta alloy has been surface-processed with CW CO2 -laser radiation and with an electron beam in order to study microstructure refinement and test the advantage of using alloys as opposed to film-on-substrate combinations for the developement of claddings.
Fundamentals of Energy Beam Interactions with Solids
Authors: Brown W. L.
Published: March 2011

High intensity pulsed beams of photons, electrons and ions provide extremely efficient means for electronically exciting solids near their surfaces. Among these three, laser beams with ever-increasing time resolution have also served as diagnostic probes to clarify the picosecond time scale on which interchange of energy between the electronic and the vibrational states of solids takes place at very high excitation energy densities. Because of this rapid transfer of electronic excitation to heat, pulsed beams provide versatile tools to investigate transient thermodynamic phenomena in solids, particularly those associated with metastable phases such as amorphous silicon.
Multiplet Fine Structure of the Gd and Tb 5P Levels
Authors: Li Dongqi , Dowben P.A. , Onellion M.
Published: March 2011

Fine structure is observed in the photoemission of Gd and Tb 5p levels as a result of multiplet splitting. These splittings are the consequence of different J final states that occur as a result of interactions with partly filled 4f and/or 5d levels.
Structural and Magnetic X-RAY Scattering Measurements of Epitaxial Dy thin Films
Authors: Toney Michael F. , Wiesler David G. , Hermsmeier Brent D. , Farrow Robin F.
Published: March 2011

We report structural and magnetic X-ray scattering measurements of a 2000Å thick Dy film, sandwiched by LaF3 films on a GaAs(111) substrate. The structure was grow by molecular beam epitaxy with the c-axis of the Dy parallel to the LaF3 c-axis and GaAs[111] axis. For the magnetic X-ray scattering, we used a polarization analyzer and an X-ray energy near the Dy L111 absorption edge. ∆t this energy there is a resonant enhancement in the magnetic scattering intensity, and we obtained ≃-50 counts per second in the magnetic diffraction peaks.

Between 85 and 179K, bulk Dy forms a helical antiferromagnetic structure, and below 85K, it transforms into a ferromagnet. We find that the c-axis lattice constant of the Dy film has a similar temperature dependence to bulk Dy from room temperature to about 110K, but below this, the film behaves differently from bulk and is strained. The temperature dependence of the turn-angle in the helical antiferromagnetic state is similar to bulk, although a weaker dependence is observed below ∼1 10K due to magnetoelastic effects. Surprisingly, the magnetic coherence length (≃310Å) is significantly shorter than the structural coherence length (≃730Å). The transition to ferromagnetic ordering at 86K exhibits temperature hysteresis as is evident in the structural and magnetic X-ray data and in SQUID magnetometry data. We believe this hysteresis arises from a combination of the strain-energy barrier accompanying the transition and magnetic inhomogeneities in the film.
Interlayer Magnetic Coupling in Sputtered Ag/Ni Superlattices
Authors: Dos Santos Carlos A. , Rodmacq Bernard
Published: March 2011

We report results of X-ray diffractometry and magnetic measurements performed on Ag/Ni superlattices prepared by triode dc-sputtering. The X-ray results suggest structural coherence and interface sharpness whatever the thickness of the elemental layers with (111) textures for both Ag and Ni. Magnetization measurements confirm the existence of sharp interfaces. They also indicate that the magnetic moments preferentially lie in the plane of the layers whatever the Ag or Ni thicknesses. We also present evidence of the oscillatory character of the magnetic coupling of the Ni layers through the non-magnetic Ag layers, which correlates with both magnetoresistance and low-angle neutron diffraction experiments.
Influence of Layer Structure on Antiferromagnetic Exchange Coupling of Iron Films through Chromium Interlayers
Authors: Payne A.P. , Kataoka H. , Farle M. , Clemens B.M.
Published: March 2011

The effect of layer structure perturbations on antiferromagnetic coupling in Fe-Cr-Fe trilayer systems is investigated. By varying the sputtering pressure, the layer structure of Fe-Cr-Fe trilayers is systematically altered, as indicated by changes in the low angle superlattice spectra of multilayers fabricated under identical conditions. The effect of topographic roughness is investigated by fabricating identical trilayers on Cr buffer layers of different thickness. Scanning tunneling microscopy is used to measure surface roughness. In each case the saturation field is measured as a function of Cr interlayer thickness by means of tapered Cr interlayer structures in which the thickness of the spacer varies linearly from 0 to 28 Å upon a single substrate. Antiferromagnetic coupling is measured locally by means of the magneto-optic Kerr effect. Results show that although the coupling is diminished by structural perturbations, it is a remarkably robust effect which persists even in instances of poor layer structure.
Magnetic Exchange Interaction Between Fe(110) Layers across a Ag(111) Intervening Layer
Authors: Qiu Z. Q. , Gutierrez C. J. , Tang H. , Mayer S. H. , Walker J. C.
Published: March 2011

We have grown a series of Fe(110)/Ag(111)/Fe(110) sandwich structures using a PHI 430B MBE system and analyzed their magnetic properties using transmission Mössbauer spectroscopy. The heterostructures consisted of two 30-monolayer (ML) 56Fe(110) slabs separated by an intervening Ag(111) layer 2 to 35 ML thick, with a 2 ML 57Fe Mössbauer probe layer placed at one of the Fe/Ag interfaces. We found that temperature dependence of the hyperfine field in the probe layer and the saturation hyperfine field value as well stronly depend on the Ag interlayer thickness. This result demonstrates that there exists an interlayer magnetic exchange interaction between the Fe layers across Ag. In addition, preliminary evidence suggests that this is probably an RKKY interaction.
Soft X-RAY Magnetic Scattering Study of thin Films and Multilayers
Authors: Kao C.-C. , Johnson E.D. , Hastings J.B. , Siddons D.P. , Vettier C.
Published: March 2011

A brief discussion of the resonant magnetic scattering process is given. Results from recent studies of thin Fe films and Fe/Gd multilayers are used as examples to demonstrate the information can be obtained and the unique features of this technique: large resonant enhancement, sensitivity to magnitization, elemental specificity, and tunability of the penetration depth. Comparison is made with related techniques: magneto-optical Kerr effect, Faraday effect, and magnetic circular dichroism.
Ordering In Zn0.5Fe0.5Se Epilayers Grown on InP Substrates by Molecular Beam Epitaxy
Authors: Riba L. Salamanca , Park K. , Jonker B. T.
Published: March 2011

We have observed an ordered structure in Zn0.5Fe0.5Se epilayers grown on (001) InP substrates using transmission electron microscopy. The ordered structure of Zn0.5Fe0.5Se has Fe atoms occupying the (0,0,0) and (½, ½, 0) sites and Zn atoms occupying the (0, ½, ½) and (½, 0, ½) sites in the zinc-blende unit cell. Ordering is observed in both electron diffraction patterns and cross-sectional high-resolution lattice images along the < 100 > and < 110 > directions. This ordered structure consists of alternating ZnSe and FeSe monolayers along the < 100 > and < 110 > directions. Computer image simulations of the high-resolution images under various thicknesses, and defocusing conditions have been obtained and are compared with those obtained experimentally.
High-Pressure X-Ray Diffraction Studies of Elastic Anomalies in Superlattice
Authors: Fujii Y. , Ohishi Y. , Konishi H. , Nakayama N. , Shinjo T.
Published: March 2011

This paper has made an overview on elastic and structural aspects of three distinct superlattices under hydrostatic pressure up to about 8GPa, which were studied by our unique x-ray diffraction technique incorporated with a diamond-anvil cell. They are metallic fcc/fcc Au/Ni, bcc/fcc Mo/Ni, and semiconductive epitaxially-grown PbSe/SnSe superlattices. In their layer-stacking direction, both metallic superlattices show the supermodulus behavior while the semiconductive one doesn't. However, its pressure-driven cubic-to-orthorhombic phase transition, successively taking place in the SnSe and PbSe layers, has been found to significantly shift by stress due to its epitaxial growth.
Structural Properties of Epitaxial Co-Cr Superlattices
Authors: Elagoz S. , Vavra W. , Uher C. , Clarke Roy
Published: March 2011

We demonstrate the growth of epitaxially ordered Cobalt-Chromium (Co-Cr) superlattices by ultrahigh-vacuum deposition techniques. The superlattices, consisting of hcp Co (00.1) and hcp Cr (00.1) layers with their [11.0] crystallographic axes parallel to GaAs [110] have a hexagonal closed packed (hcp) structure with the c-axis normal to the film plane.
A Comparison of Growth and Magnetic Properties of FE(ll0)/AG(lll) and FE(100)/AG(100) Multilayers
Authors: Walker J.C. , Tang H. , Wieczorek M.D. , Keavney D.J. , Storm D.F. , Qiu Z.Q. , Gutierrez C.J.
Published: March 2011

Two series of Fe/Ag multilayers were grown in a Perkin-Elmer 430B MBE system, one of the Fe(110)/Ag(lll) orientation and another of the Fe(100)/Ag(100) orientation. Vastly different techniques were developed by this group and others to achieve epitaxial growth of both of these systems. Using RHEED, it was inferred that the optimal growth of Fe(110) on Ag(lll) occurred at a substrate temperature of 180° C. In contrast, the growth of Fe(lO0)/Ag(100) proceeded with the sharpest RHEED streaks at a reduced substrate temperature. We believe that these fundamentally different growth parameters are the result of physically different growth modes, conjectured to be: edge growth (Fe 110), and a more nucleated growth (Fe 100).

Accordingly, dissimilar magnetic interfacial properties are also strongly in evidence, accounted for by the structural differences associated with the different Fe planes. Furthermore, Fe(110) layers as thin as 3 ML were grown on Ag(lll) and showed no superparamagnetism and a genuine 2-dimensional behavior of M(T). However, the Fe(100) on Ag(100) multilayers in a similar thickness range exhibited strong relaxation and a comparatively reduced Curie temperature.
Magnetic Anisotropy of Epitaxial Co/Pt Superlattices
Authors: Chien C.J. , Clemens B.M. , Hagstrom S.B. , Farrow R.F.C. , Lee C.H. , Marinero E.E. , Lin C.J.
Published: March 2011

Selected orientations of epitaxial Co/Pt superlattices were grown on GaAs substrates in [001], [110], and [111] orientations using seeded epitaxy techniques. The microstructural and magnetic properties of Co/Pt superlattices are presented. The magnetic anisotropies of Co/Pt superlattices are found strongly dependent on the crystallographic orientation of the growth axis. High-resolution cross-sectional transmission electron microscopy (HRXTEM) investigation of the Co/Pt interfaces has revealed the presence of a large number of planar defects in the [111] Co/Pt superlattice. HRXTEM shows that the interface of Co/Pt is wavy and is not atomically abrupt. These findings suggest that models for the magnetic anisotropy should not be based on idealized, chemically abrupt interfaces but should incorporate magnetocrystalline anisotropy in the alloy region. We propose a model for the magnetic anisotropy based on the N6el magnetic surface anisotropy and the existence of defects in the alloy region. The easy axis of the magnetic anisotropy predicted by the model agrees with the magnetic and structural data for the superlattices.
Magnetic Anisotropy Determined from Angular Dependent Magnetization Measurements
Authors: Bloemen P.J.H. , Alphen E.A.M. Van , Jonge W.J.M. De , Broeder F.J.A. Den
Published: March 2011

It is shown that a (biaxial) vibrating sample magnetometer (VSM) can be used to determine the magnetic anisotropy of thin films. Besides the commonly measured component along the magnetic field also the component perpendicular to the magnetic field was measured. Experiments were performed in a magnetic field of fixed magnitude as a function of the angle between the field and the film plane. These type of measurements give both an accurate estimate of the magnetic anisotropy and also show when domains are formed during rotation of the magnetization. The method has been applied to determine the magnetic anisotropy of Co/Pd and Co/Cu multilayers. The results are compared to those obtained with alternative methods.
Magneto-Optical Enhancement of Tbfeco/Al Films at Short Wavelength
Authors: Song Kibong , Ito Hiroshi , Naoe Masahiko
Published: March 2011

The bilayered films composed of magneto-optical(MO) amorphous Tb-Fe-Co alloy and reflective Al layers were deposited successively on glass slide substrates without plasma exposure by using the facing targets sputtering system. The specimen films with the thickness of MO layer tMO below 5 nm showed apparent perpendicular magnetic anisotropy constant Ku of 2 to 3×106 erg/cm3 and rectangular Kerr loop. The specimen film with tMO of 14 nm took the Kerr rotation angle θk as large as about 0.36 degree, at the wavelength λ as short as about 400 nm. These values of θK is considerably larger than those of the bilayered films in the conventional MO media. Normally, the bilayered films with tMO above 50 nm took θK of about 0.25 degree at θK of 400 nm.
Spin Polarized Photoemission from Fe On CU(100)
Authors: Pappas D.P. , KÄmper K.-P. , Miller B.P. , Hopster H. , Fowler D.E. , Luntz A.C. , Brundle C.R. , Shen Z.-X.
Published: March 2011

The spin resolved electronic structure of ultra-thin Fe films on Cu(100) was investigated using spin polarized angle resolved photoemission spectroscopy. All exchange splitting of the Fe ∆s band of 2.5 eV is observed for photon energies between 20 and 30 eV. ∆ peak at 6 eV binding energy which has been previously identified as a many-electron resonance was observed only after contamination of the films with oxygen. In addition, the spin dependent attenuation lengths for electrons in Fe were measured at 11, 19, and 40 eV above Ef. The attenuation length for the minority spin electrons was found to be shorter than that of the majority spin electrons. The difference between the two attenuation lengths was shown to increase at low energy. Short attenuation lengths of ≃3 monolayer were measured at II eV. The large increase of the attenuation length at low energy which is expected from the “universal curve” is not observed in Fe.
Spin Polarization of PT in Pt/Co Multilayers Studied by X-Ray Absorption
Authors: Schütz G. , Ebert H. , Fischer P. , Rüegg S. , Zeper W. B.
Published: March 2011

Local d-magnetic moments of the Pt interlayer in Pt/Co multilayered structures (4 ÅCo + X ÅPt, X=9,19,23,30,40) have been investigated theoretically and experimentally by circular magnetic x-ray dichroism studies.

It has been found that a significant Pt polarization is induced, which contributes by about 13% to the total magnetization. The experimental findings of the average Pt moments agree well with the theoretical expectations indicating the existence of a longrange exchange coupling through the Pt layer.
Doping And Band-Gap Engineering Of An Intrazeolite Tungsten(Vi) Oxide Supralatiice
Authors: Ozin Geoffrey A. , Malek Andrzej , Prokopowicz Richard , Macdonald Peter M. , özkarb Saim , Mollerc Karin , Bein. Thomas
Published: March 2011

New results are presented concerning the topotactic self-assembly, n-type doping and band-gap engineering of an intrazeolite tungsten(VI) oxide supralattice n(WO3)-Na56Y, where O < n ≤ 32, built-up of single size and shape (WO3)2 dimers. In particular it has been found that the oxygen content of these dimers can be quantitatively adjusted by means of a thermal vacuum induced reversible reductive-elimination oxidative-addition of dioxygen. This provides access to new n(WO3−x)−Na56Y materials (0 < x ≤ 1.0) in which the oxygen content, structural properties and electronic architecture of the dimers are changed. In this way one can precisely control the oxidation state, degree of n-doping and band-filling of a tungsten(VI) oxide supralattice through an approach which can be considered akin to, but distinct in detail to, that found in the Magneli crystallographic shear phases of non-stoichiometric bulk WO3−x. Another discovery concerns the ability to alter local electrostatic fields experienced by the tungsten(VI) oxide moieties housed in the 13Å supercages of 16(WO3)−M56Y, by varying the ionic potential of the constituent supercage M+ cations across the alkali metal series. This method provides the first opportunity to fine-tune the band-gap of a tungsten(VI) oxide supralattice. A miniband electronic description is advanced as a qualitative first attempt to understand the origin of the above effects. The implications of these discoveries are that cluster size, composition and intrinsic electrostatic field effects can be used to “chemically manipulate” (engineer) the doping and band architecture of intrazeolite supralattices of possible interest in quantum electronics and nonlinear optics.
Growth, size and photoactivity of CdS, ZnS or PbS particles in NaX zeolite
Authors: Wark M. , Schulz-Ekloff G. , Jaeger N. I. , Lutz W.
Published: March 2011

CdS, ZnS or PbS dispersions are prepared in a NaX matrix by ion exchange and gas phase sulfidation. The degree of sulfidation remains incomplete in all cases. This fact can be explained by preferential bonding of the cations to the zeolite framework and to an increase of the solubility constants for quantum-size particles. Zeolite-hosted sulfide particles grow to supra-supercage size under fragmentation of the host framework. The shift of the position of the optical absorption edge correlates with the sulfide particle size obtained from transmission electron micrographs. The rate of photocorrosion of the sulfide clusters strongly depends on the particle size between 1 and 10 nm.
Zeolitic Materials As Organizing Media For Semiconductor-Based Artificial Photosynthetic Systems
Authors: Il Kim Yeong , Riley Richard L. , Huq Munir J. , Salim Samer , Le Angie N. , Mallouk Thomas E.
Published: March 2011

Two photocatalytic systems consisting of spatially organized electron donor/photosensitizer/oxide semiconductor/catalyst assemblies are described. The first consists of an aluminosilicate zeolite (mordenite or zeolite L) containing Pt clusters, methylviologen, and titanium oxide within the linear channels, together with a size-excluded photosensitizer RuL32+ (L = 4, 4-dicarboxy-2, 2-bipyridine) adsorbed at the TiO2 surface. The kinetics of photochemical charge separation and hydrogen evolution in the presence of sacrificial electron donors are reported. In the second system, a layered oxide semiconductor, K4−xHxNb6O17·nH2O, replaces the zeolite/TiO2/MV2+ composite. Using adsorbed RuL3 and visible light excitation, this material decomposes acidic iodide solutions into H2 and I3− with a quantum efficiency of 0.3 %.
Surface Chemistry Of Heterobimetallic Ge-M (M = Mo, W) Complexes In Zeolite Y
Authors: Borvornwattananont Aticha , Moller Karin , Bein Thomas
Published: March 2011

The intrazeolite chemistry of the two germylene complexes Cl2(THF)GeM(CO)5(M = Mo, W) was studied with x-ray absorption spectroscopy (Ge, Mo, W edge EXAFS) and in-situ FTIR/TPD-MS techniques. The slightly decarbonylated GeMo complex interacts with the framework of NaY zeolite at room temperature and retains the Ge-Mo bond up to about 100° C. In proton-loaded HY zeolite, framework interactions increase at elevated temperature, and the attached complex retains the Ge-Mo bond up to about 120° C. The Ge-Mo bond is cleaved at higher temperatures. MoC1x and Mo-Mo species are formed in NaY and HY zeolite, respectively, while GeClx fragments are anchored to the zeolite framework.

The complex Cl2 (THF)GeW(CO) 5 retains all five CO ligands up to about 100° C in both NaY and the proton form. Detectable anchoring occurs at room temperature in NaY and at about 80° C in the proton form. WC1x species are formed upon cleavage of the Ge-W bond at higher temperatures.
The Application Of Molecular Sieves As Magnetic Resonance Imaging Contrast Agents
Authors: Balkus Kenneth J. , Bresinska Iwona , Kowalak Stanislaw , Young Stuart W.
Published: March 2011

The application of zeolite molecular sieves as Magnetic Resonance Imaging (MRI) contrast agents is presented. Recent progress is described for X, Y and A type zeolites modified with paramagnetic species.
Synthesis And Water Sorption Properties Of Aluminophosphate (AlPO4) And Silicoaluminophosphate (Sapo) Molecular Sieves
Authors: Malla P. B. , Komarneni S.
Published: March 2011

Aluminophosphate (AlPO4–5, AlPO4–11, AlPO4–17, AlPO4–20) and silicoaluminophosphate (SAPO-5, SAPO- 11, SAPO-17, SAPO-20) molecular sieves of varying pore sizes (3–8 Å) were synthesized and their water adsorption and desorption properties were studied. Water sorption isotherms of AlPO4 molecular sieves were characterized by unusual isotherm shapes, that is, little or no initial adsorption followed by extreme adsorption leading to volume filling by hydrogen bonding and cooperative interaction in micropores, apparently due to the nonpolar nature of pore surfaces coupled with weak (reversible upon evacuation) chemisorption of water, and hysteresis loops extending to very low pressures. Although micropore filling in AlPO2's and isostructural SAPO's was completed almost at the same relative pressure (p/po), SAPO's exhibited less extreme adsorption isotherms as a result of their slightly more polar nature of pore surfaces compared to AlPO4's. Neither AlPO4apos;s nor SAPO's exhibited Brunauer Type I isotherms with water, contrary to a general expectation of the hydrophilic microporous solids.
The Hydrothermal Synthesis of Layered Molybdenum Phosphates with Octahedral-Tetrahedral Layers
Authors: Haushalter Robert C. , Mundi Linda A.
Published: March 2011

While we have prepared and structurally characterized over forty solids in the octahedral-tetrahedral framework molybdenum phosphate (MoPO) system, including molecules, 1-D polymers and 3-D materials, this paper will focus on the two dimensional layered MoPO's. Both covalently and H bonded layers will be discussed. Compounds covered include Na3[Mo2O4(HPO4)(PO4)]·2H2O, (Et2NH2)2[Mo4O8(PO4)4/2], Cs2Mo4P6O26, (4-phenylpyridie)2[Mo4O8(PO4)4/2], (cation)[Mo2O2(PO4)2(H2PO4)], with several different types of organic and inorganic cations, and (4-phenylpiperidine)4[Na2.5Mo6O15(H1.4PO4)4]·4H2O. These materials might provide a platform for the preparation of new types of pillared and intercalated inorganic solids.
Flexibility Of The Zeolite Rho Framework: The Redistribution Of Extra Framework Cations As A Function Of Temperature.
Authors: Parise John B. , Liu Xing , Corbin David R. , Jones Glover A.
Published: March 2011

Upon heating Ba2+, Sr2+ and Cd2+-exchanged zeolite RHO, abrupt changes have been observed in the cubic unit cell parameters [1–3]. Calculations of the powder x-ray diffraction patterns indicate these changes result from relocation of the extra-framework cations. For Ba2+ and Sr2+-exchanged RHO, a shift from the single 8-ring (S8R) to the double 8-ring (D8R)-site is accompanied by contraction of the unit cell. However, for the Cd2+-exchanged material relocation from the S8R to the single 6-ring (S6R)-site coincides with cell expansion. Further, with relocation of Cd2+ the low temperature acentric (A) form is transformed to a centric (C) structure above 300°C. The shift of Cd2+ ion occurs over a distance of 5.7Å, the largest observed in a zeolite.
129Xe Nmr As A Probe Of Microporous Materials
Authors: Ripmeester John A. , Ratcliffe Christopher I.
Published: March 2011

It is shown that the interpretation of 129Xe chemical shift measurements in microporous solids is not simple, and that considerable caution must be used both in the measurement and interpretation of results, especially for large pore systems. Nevertheless, useful information can be obtained on the phase diagram of xenon in pore systems, and on transport within the solid and between the solid and the gas phase.
Ultrathin Soi Structures by Low Energy Oxygen Implantation
Authors: Namavar Fereydoon , Cortesi E. , Buchanan B. , Manke J. M. , Kalkhoran N. M.
Published: March 2011

Although silicon-on-insulator (SOI) materials made by standard energy (150–200 keV) SIMOX processes have shown great promise for meeting the needs of radiation hard microelectronics, there are still problems relating to the radiation hardness and economic viability of standard SIMOX. A low energy SIMOX (LES) process reduces cost and improves radiation hardness and increased throughput of any implanter because much smaller doses are required. In addition, the process is uniquely able to produce high quality thin SIMOX structures that are of particular interest for fully depleted device structures. In this paper, we address the formation of high quality ultrathin SIMOX structures by low energy implantation.
Dynamics of Change in Electrical Conductivity of Ion Irradiated Amorphous Silicon.
Authors: Shin Jung H. , Im J. S. , Atwater H. A.
Published: March 2011

The dynamics of relaxation of amorphous silicon after unrelaxation (creation of defects) by irradiation with 600 KeV Kr++ ions is investigated using the changes in electrical conductivity of amorphous silicon. By measuring the conductivity of such unrelaxed amorphous silicon after being partially relaxed by isochronal anneals in a temperature range from 383 to 873° K, it is shown that conductivity of amorphous silicon decreases monotonically by up to 3 orders of magnitude as it relaxes; i.e. that conductivity is a measure of the degree of relaxation. Furthermore, it is found that such change in conductivity can be completely reversed by a subsequent unrelaxation with ion irradiation. Continuous in situ measurements of conductivity of amorphous silicon before, during and immediately after irradiation in a temperature range from 77 to 573° K show that relaxation occurs even at 77°K. Finally, the relaxation of amorphous silicon thus measured is linear when plotted against ln(t), a behavior that is characteristic of relaxation with a spectrum of activation energies.
Growth of ion implanted buried FeSi2 on Si (111) and Si (100)
Authors: Radermacher K. , Mantl S. , Dieker Ch. , Holzbrecher H. , Speier W. , Lüth H.
Published: March 2011

Buried FeSi2 layers have been fabricated by 200 keV Fe+ implantations into (111) and (100) Si substrates. By varying the dose from 0.4 to 7.1017 Fe+ cm−2 the dependence of the Fe concentration on ion dose was investigated systematically. The samples were characterized by Rutherford backscattering spectrometry, He+ ion channeling and secondary ion mass spectroscopy. In the as-implanted state the Fe peak concentration increases lineary with dose up to ≈2.4.1017 Fe+ cm−2. Above this dose a redistribution of Fe atoms was observed as indicated by comparison of measured depth profiles with Monte-Carlo simulations of high dose implantations. The Fe peak concentration shows an unusual dose dependence after rapid thermal annealing (RTA) at 1150°C for 10 s. A minimum dose of (2.4±0.1)1017 Fe+ cm−2 for (111) Si and a slightly higher dose of (2.7±0.1).1017 Fe+ cm−2 for (100) Si is necessary to form continuous metallic αFeSi2 layers.
XPS Investigation of Ion Implanted PMMA
Authors: Kallweit R. , Roll U. , Strack H. , Pocker A.
Published: March 2011

During ion bombardment, polymethylmethacrylate (PMMA) shows degassing of polymer components with a fluence and energy dependent contraction of the material, which leads to a material modification.

The ion beam induced chemical modification of the implanted layers was examined by means of X-ray photoelectron spectroscopy (XPS). The dependence of the chemical modification on beam current, ion fluence and ion energy was investigated for nitrogen implantations at energies ranging from 50 keV to 400 keV for ion fluences between 7×1013 / cm2 and 7×1015/cm2. Compared with the C-spectrum of virgin PMMA, the spectra of the implanted layers exhibited an increase of intensity of the 284.5 eV peak and the 286.4 eV peak. The ion beam induced modification led basically to generation of new C-o-groups. These generations show drastical changes in the dependence of the beam current and the ion fluence. Nevertheless, at a constant dose of 2×1014/cm2 the concentrations of the new groups did not indicate any energy dependence.
A New Method for Measuring Ion Implantation Amorphous Dose In Situ
Authors: Yuan Jianzhong , Verner Igor V. , Corbett James W.
Published: March 2011

An in situ method for determining the ion implantation dose necessary to make Si amorphous is developed and utilized. This method is based on measuring ion-implantation-induced in-plane stress. Measurements are carried out for various low energy ions implanted into thin p-type (100) Si. The doses necessary to make Si amorphous obtained by this method are in good agreement with previous data. This technique is sensitive, informative, quick, visual and nondestructive.
Mossbauer Study of the Role of Aluminum and Chromium in Nitrogen Implanted Iron
Authors: Kopcewicz M. , Jagielski J. , Turos A. , Williamson D. L.
Published: March 2011

The role of alloying elements such as Cr and Al in the formation and stability of the nitride phases formed due to N ion implantation into metallic iron was studied by conversion electron Mössbauer spectroscopy (CEMS). The thermal stability of nitride phases upon 1 h annealing was greatly increased as a result of co-implanting either Cr or Al with N as compared to pure α-Fe implanted only with N.
The Effect of Thermal Spike on the Ion Irradiation Induced Grain Growth
Authors: Chae K. H. , Song J. H. , Joo J. H. , Woo J. J. , Whang C. N. , Oh Y. J. , Jung H. J.
Published: March 2011

The relation between the ion irradiation induced grain growth in bilayer system and the basic parameters involved in ion beam mixing process was studied. TEM micrographs showed that a significant grain growth has been induced by Ar+ irradiation at room temperature. The grain size increases rapidly in low dose region, while it approaches a saturated value in high dose region, and it has close relationship with thermodynamic properties such as cohesive energy ( ΔHc ) and heat of mixing( ΔHm ). The experimental results are in good agreement with the model for the grain growth based on the thermal spike induced atomic migration.
Novel Paths for Nucleatton and Growth of Thin Films by Ionized Cluster Beam (ICB) Techniques: Atomic-Scale Observations
Authors: Yamada I. , Yamada T. , Takaoka G. H. , Usui H. , Current M. I.
Published: March 2011

Atomic-scale observations by STM and TEM of the early stages of film growth and recent studies of the detailed composition of beams from ICB sources have led to new understandings of origins of some of the extraordinary properties of thin films deposited by ICB methods. The presence of a small fraction of atoms in the form of large clusters initiates a novel sequence of film growth steps starting with the immediate formation of stable islands for film growth. The growth of films from cluster-initiated islands leads to fundamentally altered film properties (compared to atomic beam, MBE, deposition) such as the epitaxial alignment of metal/semiconductor/ceramic multilayers grown near room temperature.
Formation of Aluminum Films Using a High Rate ICB Source
Authors: Tsukazaki H. , Okamoto G. , Hashimoto Y. , Yamanishi K. , Tanaka M. , Yasunaga S.
Published: March 2011

An ionized cluster beam (ICB) source has been developed for high rate deposition, and its possible application to ultra large scale integrated circuit (ULSI) metallization was investigated. Aluminum films were deposited onto oxidized silicon wafers using the ICB source. It was shown that an electrical resistivity was almost the same as the value for bulk aluminum, and the surface morphology of deposited films was improved by controlling the ionization and acceleration conditions of the cluster beam. It was confirmed that the ICB method showed an excellent coverage profile in contact holes when compared with the conventional sputtering method. Using the directivity of cluster beams, contact holes of 1.5 in aspect ratio were successfully metallized. From these results, it became evident that the ICB source is a favorable method for ULSI metallization.
Epitaxial Al(110) Films Grown On Heavily-Doped Si(100) by Cluster Beam Deposition.
Authors: Wada S. , Current M. I. , Takaoka G. H. , Usui H. , Yamada I.
Published: March 2011

ABSTRACT:Epitaxial Al films have been grown on heavily doped Si(100) by neutral cluster beam deposition. The Al films were evaluated by RBS, RHEED, optical interference roughness maps and STM imaging. The results were consistent with the formation of epitaxial Al (110) bi-crystals similar to films grown by ionized cluster beam deposition on lightly-doped Si
TEM Study of Flux Pinning Defects in YBa2Cu3O7-δProduced by 580 MeV Sn Ion Irradiation
Authors: Wheeler R. , Kirk M. A. , Brown R. , Marwick A. D. , Civale L. , Holtzberg F. H.
Published: March 2011

Recent studies of high Tc superconductors irradiated with high energy heavy ions have indicated that a defect structure is produced which is extremely effective in pinning magnetic flux lines. In attempting to develop models to account for these observations, it is imperative to have a complete characterization of the defects responsible for the property enhancements. Hence, the defect microstructure produced in single crystal YBCO by 580 MeV Sn30+ irradiation, recently demonstrated to provide highly effective flux pinning at high fields and temperatures, has been investigated by conventional transmission electron microscopy. This irradiation condition is shown to produce linear, yet segmented, tracks of damaged material, approximately aligned with the incident irradiation direction, throughout the entire crystal thickness of 22μm. The cross sectional density of damage tracks is in close agreement with the ion fluence. Two specific characteristics of the track morphology have been studied, namely, their continuity and angular spread. The continuity of the tracks does not appear to follow threshold-like behavior within the electronic loss range studied here and the angular distribution of the defect track directions is only approximated by the Monte Carlo calculations of TRIM.
Nanoscale Y2O3 Phase Dispersion in YBa2Cu3O7−x Thin Films Produced by Plasma-Enhanced Metalorganic Chemical Vapor Deposition
Authors: Lu P. , Zhao J. , Chern C. S. , Li Y. Q. , Kulesha G. A. , Gallois B. , Norris P. , Kear B. , Cosandey F.
Published: March 2011

Transmission electron microscopy has been used to investigate the microstructure of YBa2Cu3O7−x thin films deposited by Plasma-Enhanced Metalorganic Chemical Vapor Deposition. The films with the best superconducting properties of Tc ∼90K and Jc>106A/cm2 at 77K and OT were either Y-rich or both Y- and Cu-rich relative to the ideal 1:2:3 composition. In the Y-rich thin films, nanoscale yttria(Y2O3) precipitates have been identified. The precipitates with an average size of about 50Å and densities as high as 1024/m3 are uniformly distributed and highly oriented with respect to the matrix. Excess Cu in the Cu- and Y-rich films leads to formation of large CuO particles on the film surface but does not have any effect on formation of nanoscale Y2O3 phase within the films. The Y2O3 precipitates may act as flux pinning sites for high critical current densities.
Low-Energy AR+ Implantation of Uhmw-Pe Fibers: Effect on Surface Energy, Chemistry, and Adhesion Characteristics
Authors: Schalek R. , Hlavacek M. , Grummon D. S.
Published: March 2011

Ultra-high molecular weight polyethylene (UHMW-PE) has a highly chain-extended and crystalline structure which is functionally inert and requires surface-modification before it can successfully operate as a reinforcement in polymer-matrix composites. Although plasma treatments are adequate for this purpose, recent work has shown that irradiation with low-energy inert gas ions can produce increases in interfacial shear strength (ISS), in epoxy matrices, which exceed those of commercial plasma treatments, and cause little degradation in tensile properties. Low energy ions are readily produced in high-current beams using gridded sources having moderate cost, and processing times may be a short as a few seconds. In this paper, we present results of recent experiments using argon ions accelerated to energies between 100 eV and 1 keV to irradiate 20–30 μm diameter UHMW-PE fibers to doses between 1×1016 and 1×1017 cm−2, and compare our findings with previous work at higher accelerating potentials. At the optimum dose (which increases with decreasing energy), greater than 9-fold improvements in ISS level, measured in epoxy-resin droplet pulloff tests, were found for ion irradiation at 0.25 keV. Scanning electron microscopy of fiber surfaces, of ion irradiated as well as commercial oxygen plasma-treated materials, revealed small crack-like pits in both cases, with the pits smaller and more uniformly distributed on the ion-irradiated fibers. Surface chemistry studies using X-ray photoelec-tron spectroscopy (XPS) and attenuated total reflectance Fourier-transform infrared spectroscopy (ATR-FTIR) indicate that irradiation resulted in high surface concentrations of polar functional groups, and extensive surface oxidation. This was accompanied by a substantial increase in the polar component of surface energy, which resulted in improved fiber wetting by the resin.
Origin of the Laser-Induced Broad Band Luminescence from a WF6/H2/Ar Gas Mixture
Authors: Heszler P. , Mogyorósi P. , Carlsson J.O.
Published: March 2011

The origin of the ArF excimer laser induced luminescence from a WF6/H2/Ar gas mixture was investigated. The experiments prove that the emission originates from excited W clusters with a size of about 10-20 nm. The influence of the H2 and Ar concentrations, the laser fluence and the repetition rate on the light intensity was studied.
Demonstrating the Utility of Boron Based Precursor Molecules for Selective Area DepositIon in a Scanning Tunnelling Microscope
Authors: Perkins F. Keith , Onellion M. , Lee Sunwoo , Dowben P.A.
Published: March 2011

The scanning tunnelling microscope (STM) can be used to selectively deposit material from a gaseous precursor compound. Ultrasmall (less than a 100 nm across) spatial dimensions for selective area deposition may be achieved by this means. In this paper we outline a scheme forselecting and designing main group cluster compounds and organometallics for this type of selective area deposition using nido-decaborane(14) as an example.
The Formation of Rugged Surface Polycrystalline Silicon Using Cl2/O2 Plasmas: The Role of Oxygen
Authors: Ozawa N. , Ikegami N. , Miyakawa Y. , Kanamori J.
Published: March 2011

The formation of rugged surface polycrystalline silicon (poly-Si) using Cl2/O2 plasmas in which O2 concentration is 0-10 % has been investigated. Phosphorus doped poly-Si (n+ poly-Si) surface is rugged by the plasma etching under the condition that O2 concentration are 1-5 % at 10 Pa, but is not rugged at 1.3 Pa. On the other hand, undoped poly-Si surface is not rugged in Cl2 /0-10 %O2 plasmas at 10 Pa. Oxygen and phosphorus play an important role in the ruggedness of n+ poly-Si. The ruggedness mechanism has been investigated using scanning electron microscope, optical emission spectroscopy and mass spectrometry. The ruggedness mechanism is suggested that in Cl2 plasmas added a small amount of oxygen, n+ poly-Si is etched selectively at the grain boundaries which contain more phosphorus than in grains. The Cl emission intensity and n+ poly-Si etch rate reach maximum in Cl2/3 %O2 plasma at 1.3 Pa. Oxygen has a possibility of promoting SiCIx dissociation and increasing Cl radicals.