bluuebunny/crossref_metadata_2025 huggingface dataset:
Metastable Crystalline Phases Synthesized by Ion Beam Mixing in Some Nb-Based Binary Metal Systems
Authors: Liu B.X. , Zhang Z.J.
Published: March 2011

In the Nb-rich Nb-Fe(Co,Ni) multilayered films, two metastable crystalline (MX) phases of hep and fee structures were formed by room temperature 200 keV xenon ion mixing. The phase formation was through a two-step transition, Le. a first shearing of bcc—>hcp and then a sliding of hep—>fcc. The free energy curves of the observed MX phases were calculated and included into the free energy diagram together with those of the terminal solid solutions, the amorphous phase and the equilibrium intermetaШc compounds. An independent comparative thermal annealing experiment was conducted with the corresponding as-deposited multilayers and the results certified the emerging sequence of the MX phases being exactly the same as the calculated diagram predicted. Moreover, a crystallographic model was figured out for the bec—>hcp—>fcc transition and the resultant lattice parameters agreed well with the experimental ones.
A View of the Commercial Application of Ion Implantation for Silicon VLSI Manufacturing
Authors: Current Michael I.
Published: March 2011

The development of ion implantation for doping of Si-IC devices is reviewed with a special focus on some of the commercial as well as technological factors.
Ion Implantation Doping of Semi-Insulating Polycrystalline Silicon
Authors: Lombardo Salvatore , Campisano S. U.
Published: March 2011

The study of doping of silicon nano-grains in semi-insulating polycrystalline silicon is of paramount importance since intense room-temperature luminescence at 1.54 µm has been demonstrated in this silicon-based semiconductor when doped with erbium ions. We have investigated the formation of p- and n-type layers of semi-insulating polycrystalline silicon by implantation and diffusion of B, P, As, and Er. The room-temperature resistivity can be changed by more than six orders of magnitude for both p- and n-type doping. A dramatic decrease of resistivity is observed for dopant concentrations above a threshold level; this effect is explained by assuming that the free-carrier motion is limited by grain boundary barriers and the electrical conduction is due to thermionic emission and tunneling of the carriers through the barriers. The prevalence of one mechanism over the other depends upon temperature, oxygen concentration and doping. In the undoped material the barrier height is large (≈ 0.5 eV), but for dopant concentrations above the threshold, it decreases with the doping level. Correspondingly, the conductivity increases by many orders of magnitude. The determination of the threshold value allows the evaluation of donor and acceptor grain boundary trap densities. Diodes have been fabricated by implantation and diffusion of boron and erbium. The I-V characteristics of these diodes are interpreted on the basis of the material modeling.
The Effect of Mass Resolution During Ion Implantation on Defect Formation and Electrical Properties in Gallium Arsenide.
Authors: Jasper Craig , Klingbeil Scott , Jones K.S. , Robinson H.G.
Published: March 2011

Control of threshold voltage during gallium arsenide (GaAs) Metal Semiconductor Field Effect Transistor (MESFET) processing is critical. Channel formation typically is done using ion implantation of 29Si+ from a SiF4 source. The use of Si+ presents a variety of potential cross-contamination problems. 28Si+ and 30Si+ beams can become contaminated with 28N2+, 28CO+, and 30NO+. While 29Si+ is relatively pure, the abundance of 29Si+ in the mass spectrum is 4.67%, thus reducing the potential beam current. This study investigates the effects of varying the mass resolving power of an Eaton 6200AV implanter on the electrical parameters and defect formation. The mass resolving power was adjusted by changing the mean path size through the slit of the aperture opening and magnetic separator current. Electrical device characterization measured a small shift in saturated source-drain current (Idss) and break down voltage, while threshold voltage shifts of approximately 80 mV were observed, with the various mass resolution powers. Transmission Electron Microscopy (TEM) showed that there is minimal change in the extended defect density with changes in isotope and aperture opening. Secondary Ion Mass Spectrometry (SIMS) measured the amount of cross contamination and these results correlated well with the observed changes in device electrical properties.
Discharge-Pumped VUV F2 Molecular Laser Annealing of Heavily Se+-Implanted GaAs
Authors: Shibata Hajime , Makita Yunosuke , Yamada Kawakatsu , Uchida Yutaka , Satoh Sabro
Published: March 2011

The capability of discharge-pumped vacuum ultraviolet F2 molecular laser for laser annealing of heavily ion implanted semiconductor was demonstrated for the first time using Se+ heavily ion implanted GaAs. Cr-doped semi-insulationg GaAs wafers were used as the substrates, and the Se+ implantation energy and dose were controlled to 100 keV and 1× 1015 cm-2, respectively. Samples were annealed using a F2 molecular laser ( wavelength = 157 nm ) with a single pulse ( width ~ 20 ns ) in the energy density range from 200 to 800 mJ/cm2 in a nitrogen atmosphere. In addition, furnace annealing was done on separate samples at 850 ºC for 20 minutes in a purified hydrogen atmosphere for comparison. Characterization of the samples was carried out using Raman scattering and ellipsometry. The laser annealed samples exhibited intense Raman scattering LO phonon peaks whose intensity increased with increasing laser power density, whereas the furnace annealed samples exhibited a very weak LO phonon peak. It was demonstrated for the first time that VUV photons can be very effective in annealing ion implantation damage as compared with conventional furnace annealing. The behavior of Raman scattering spectra as a function of laser energy density was explained quantitatively by a “spatial correlation” model. The model made it possible to estimate the average size of the recovered crystal regions in samples for any given laser energy density.
Optical and Structural Properties of MeV Erbium Implanted LiNbO3
Authors: Fleuster M. , Buchal CH. , Snoeks E. , Polman A.
Published: March 2011

LiNbO3 single crystals were implanted with Er ions at 3.5 MeV with fluences up to 3*1016 Er/cm2 and subsequently annealed at 1060°C. The warm-up rate of the sample determines whether the implanted, amorphized surface layer recrystallizes via columnar or via layer-by-layer solid phase epitaxial (SPE) growth. The maximum concentration of optically active Er ions is determined to be 0.18 at.%.
Ion-Implanted Thin Film Phosphors for Full-Color Field Emission Displays
Authors: Kalkhoran Nader M. , Maruska H. Paul , Namavar Fereydoon
Published: March 2011

We have investigated the application of ion implantation technique for introducing activator and co-activator ions into host materials such as ZnS and Zn2SiO4, and have produced phosphors with differing emission peaks throughout the visible range. A number of different ions including, Mn+, Al+ and rare-earth metals have been implanted. Zn2SiO4:Mn showed bright yellow cathodoluminescence. We have demonstrated that by varying the parameters for ion implantation and annealing, a single ZnS sample with emission peaks ranging from violet to yellow can be produced; i.e, chromaticity engineering. In one case, our results indicated that photoluminescence (PL) spectrum of ZnS phosphors shifts from blue to green by increasing the dose of implanted A+ ions. The Al+-implanted ZnS samples showed emission peaks shifting from 440 to 510 nm when the aluminum dose was raised from 1 × 1015 to 1 × 1017 A1+/cm2. Therefore, by activating color centers in thin film phosphors using ion implantation, efficient and low-cost full-color field emission displays can be fabricated on a single layer of host material.
Ion Implantation into High-Speed Steel for Improved Tribology
Authors: Hirvonen J-P. , Rück D. , Yan S. , Lappalainen R. , Torri P.
Published: March 2011

Ion implantation into steels with a martensitic microstracture is reviewed and discussed in terms of different implanted species and observed changes in the structure. Both single ion and dual ion implantation treatment are included. The disability of the nitrogen ion implantation to improve the tribological characteristics of steels with a martensitic microstructure can be overcome by dual implantation of titanium and carbon, for example. Results of tribological tests on samples in which titanium is replaced by chromium are more controversial, although changes in the sliding characteristics were observed. Dry sliding on the samples implanted up to 1018 ions/cm2 is totally different by nature and -based on the reported results- associated with the formation of carbon precipitates on the surface. The thermal stability of implanted nitrogen and carbon in MЗ high-speed steel was examined and nitrogen was shown to be less stable than carbon. Mechanical and tribological properties were further changed by heat treatment after ion implantation, which indicates that temperature is also a critical parameter during ion implantation.
Tribomechanical Property Modification of Commercial TiN Coatings by Carbon Ion Implantation
Authors: Liu L.J. , Sood D.K. , Manory R.R.
Published: March 2011

About 2 μm thick commercial coatings of TiN on high speed steel substrates were implanted at room temperature with 95 keV carbon to nominal doses between 1 × 1017 and 8×1017 ions cm-2. An ultra-microhardness apparatus (UMIS-2000) was used to measure hardness, and a pin-on-disc machine (CSEM Tribometer) with a sapphire ball was used to measure wear, friction and adhesion. Carbon implantation induced a significant improvement in ultra-microhardness, friction coefficient and wear properties. The surface microhardness increases monotonically by up to 115% until a critical dose φ crit is reached. Beyond this dose the hardness decreases, but remains higher than that of unimplanted sample. A lower friction coefficient and a longer transition period towards a steady state condition were obtained by implantation. An improvement of up to four times in the wear is obtained after carbon implantation. Topology studies with SEM show a change in the mode of wear. The changes in tribomechanical properties are discussed in terms of radiation damage and possible second phase formation.
Reduction of Defect Fluxes Using Dual-Ion-Beam Processing
Authors: Iwase A. , Rehn L. E. , Baldo P. M. , Okamoto P. R. , Wiedersich H. , Funk L.
Published: March 2011

Radiation-induced segregation (RIS) in Ni-12.7% Si and Cu-1% Au alloys was studied using Rutherford backscattering spectroscopy during He and Ne irradiation at elevated temperatures. During single ion-beam irradiation with 1.5 MeV He, strong RIS of Si toward the surface was observed in Ni-12.7% Si. Simultaneous irradiation with 400 keV Ne and 1.5 MeV He almost completely suppressed the Si segregation, even when the calculated damage production rate by Ne was only a few percent of that by He ions. A similar effect of dual-beam irradiation was observed in the Cu-1% Au alloy, i.e., the rate of near surface Au depletion was strongly reduced under simultaneous irradiation. The present result shows that dual-beam irradiation can be applied to control RIS and RED (Radiation Enhanced Diffusion) during ion beam processing.
Surface Modification of Electromagnetic Railgun Components
Authors: Otooni M. A. , Graf A. , Dunham C. , Brown Ian , Yao Xiang
Published: March 2011

Copper and aluminum used for rail and armature materials in electromagnetic railgun systems undergo severe degradation during the EM gun operation. The extent of this degradation is especially severe in guns operated at high energy levels or designed for repeated firings. In an effort to improve surface properties of the copper rail, armature, and sabot materials, the technique of metal ion implantation using a vacuum arc ion source has been employed. Preliminary tests have been conducted to identify the best implant species to improve spark erosion resistance, scratch resistance and hardness. The implanted species included Al, Ti, Cr, Ni, Ta, Ag, and W. The implantation energy range and dose varied between 100–180 KeV and 0.4 to 2 × 1017 cm-2, respectively . Several analytical techniques were also used to assess the effect of implanted species. These included Rutherford Back Scattering (RBS), Scanning Electron Microscopy (SEM), Transmission Electron Microscopy (TEM), Microhardness Measurements, Spark Erosion and Scratch Testing. It has been tentatively concluded that Ta and Ni implantation of the copper rail substantially improve wear and inhibit arc erosion. There is also sufficient evidence to indicate that implantation of the aluminum armature with Cr and Ta, involving two stages of implantation, will also improve its mechanical and wear properties.
Ion Implantation Distribution Study in Biological Samples
Authors: Lu Ting , zhu Fengsui , Zhou Shanyuan
Published: March 2011

The organic materials of biological samples such as wheat, rice, corn and bean were implanted by nitrogen irons with energy ranging from 35–180 KeV. Biological effects including physiological and genetic variations on these crops were induced by ion implantation. In order to understand the role played by ion implantation, the distributions and the ranges of the implanted ions in biological samples were measured by RBS spectrometry. Theoretical calculations of the ranges were carried out using TRIM program. The results of experimental measurement were found essentially the same as the calculated values. The mechanism of the biological variations induced by ion beams is discussed.
Effect of Ion-beam Radiation on the Anisotropy of Resistivity in YBa2Cu3O7-δ Thin Films
Authors: Wu J. Z. , Zhang Z. H. , Chen V. W. , Yu N. , Chu W. K.
Published: March 2011

Different behaviors of the normal-state resistivity have been observed in (110)-, (113)- and a-oriented YBa2Cu3O7-δ thin films under 200 keV H+ irradiation. It suggests that the c-axis electrical conduction is very sensitive to nonoxygen point defects and a ”semiconductor-metal” phase transition could be induced at very low densities of these defects.
A More Efficient Approach for Monte Carlo Simulation of Deeply-Channeled Implanted Profiles in Single-Crystal Silicon
Authors: Yang Shyh-Horng , Lim David , Morris Steven J. , Tasch AL F.
Published: March 2011

In this paper is reported a new approach for the Monte Carlo simulation of deeply-channeled implanted profiles in single-crystal silicon which has greatly improved efficiency. This approach has been successfully implemented in the UT Monte Carlo code (UT-MARLOWE). A time savings of up to 212X has been observed with a 4-stage simulation. A simulation of arsenic implants with 15 keV implant energy typically takes about 12 minutes on a workstation.
High Resolution Triple Axis Diffractometry in Indium-Carbon and Gallium-Carbon Co-implanted Gallium Arsenide
Authors: Horng S.T. , Madok J.H. , Haegel N.M. , Goorsky M.S.
Published: March 2011

High-resolution x-ray triple axis diffractometry was used to characterize damage recovery in gallium arsenide implanted with gallium or indium ions, and co-implanted with carbon ions. From reciprocal space mapping around the (004) reciprocal lattice point, the evolution of residual strain and the lattice plane tilt induced by the ion implantation and annealing processes were analyzed. The lattice damage in implanted gallium arsenide is dependent on the dose and ion type; annealing subsequently alters the structural properties of the material. For example, In/C co-implanted gallium arsenide shows a greater amount of residual damage as compared to Ga/C co-implanted gallium arsenide after rapid thermal annealing at 885 °C for 5 seconds. For a given Group III ion / C co-implant, we observe the highest p-type activation when the Group III ion and C implant doses are the same. Increasing the Group III ion dose reduces the material quality and has a concomitant negative effect on the electrical properties of the material. These results suggest that reciprocal space maps can provide insight into the relationship between the structure and properties of implanted compound semiconductors.
Channeling in LiNbO3 :Fe Modulated by Holographic Stress Field Superlattice
Authors: Kukhtarev N. , Kukhtareva T. , Ila D. , Williams E. K. , Zimmerman R. L. , Caulfield H. J.
Published: March 2011

Photon and proton channeling have been observed in LiNbO3:Fe crystals which have holographically recorded electric field gratings. An analogy between photon and proton channeling is developed and compared with the experimental results.
Crystallographic Structure of Mesotaxial IrSi3 in Si
Authors: Hinneberg H.-J. , Sjoreen T. P. , Chisholm M. F.
Published: March 2011

A buried epitaxial IrSi3 layer has been produced in (111) oriented Si by high dose Ir+-implantation (1 MeV, 1.7×1017 Ir+/cm2, 550°C) and subsequent annealing (5 h at 1100°C). Transmission electron microscopy and ion channeling show that the hexagonal IrSi3 prefers to form with its (2110) plane oriented parallel to Si(111), while its [0001] direction is parallel to either [112], [121], or [211]. Thus, the IrSi3 film is made up of three differently oriented crystals, each occupying about 1/3 of the suicide volume.

A dose of 3.5×1016 Ir+/cm2 leads to the formation of a band of large, isolated precipitates. They have the same epitaxial relationship to Si, but the Si(111) plane is no longer the only one to which the (2110) of IrSi3 is parallel. Instead precipitates are also observed oriented parallel to (111), (111), and (111) in Si in roughly equal numbers. Consequently, there are now 12 possible orientations of IrSi3 crystals. We assume that strain relief and interface area minimization are the main factors suppressing the additional orientations in the continuous IrSi3 films formed by the coalescence of precipitates at higher doses.
Si Ion Implantation for Secondary Defect Reduction in Simox Material
Authors: Ellingboe S.L. , Ridgway M.C.
Published: March 2011

A novel methodology for altering the amount and/or nature of post-anneal disorder in SIMOX substrates has been investigated. A pre-anneal, secondary Si-ion implant (with an ion range less than that of the primary O-ion implant) is shown to effectively getter Si interstitials to the near-surface region during annealing. As a consequence, post-anneal disorder at the front. Si/SiO2 interface is significantly reduced. Alternatively, a Si-ion implant with an ion range greater than that of the O-ion implant can alter the post-anneal disorder at the back Si/SiO2 interface.
Ion Damage Studies in GaAs/Al0.6Ga0.4As/GaAs Heterostructures
Authors: Turkot B.A. , Forbes D.V. , Xiao H. , Robertson I.M. , Coleman J.J. , Kirk M.A. , Rehn L. E. , Baldo P.
Published: March 2011

The development of the damage structure produced in (100) GaAs/Al0.6Ga0.4As/GaAs by 1 MeV Kr+ ion irradiation at 77 and 293 K has been investigated by RBS channeling and cross-sectional high-resolution TEM techniques. Following an implantation to a dose of 1014 ions cm-2 at 77 K, RBS channeling spectra indicate that the Al0.6Ga0.4 layer contained a high defect density and was possibly amorphous. Warming to room temperature resulted in a change in the channeling spectrum, which indicated that the damage in the Al0.6Ga0.4As layer had partially recovered. The degree of recovery was greatest at the GaAs/ Al0.6Ga0.4As interface, and decreased with increasing depth. TEM observations show the damage in the Al0.6Ga0.4As to be comprised of planar defects, the density of which increases with depth, and an amorphous layer at the bottom interface. This difference in the damage distribution is consistent with the asymmetry in the channeling spectrum. A model based on the depth variation of cascade density is proposed to account for the observations.
Stresses in Ion Assisted Deposited Oxide Thih Films
Authors: Ghanashyam Krishna M. , Al Robaee Mansour , Kanakaraju S. , Narasimha Rao K. , Mohan S.
Published: March 2011

Thin films of Ceria, Titania and Ziroonia have been prepared using Ion Assisted Deposition(IAD). The energy of ions was varied between 0 and 1 keV and current densities up to 220 μA/cm were used. It was found that the stress behaviour is dependent on ion species, i.e. Argon or Oxygen, ion energy and current density and substrate temperature apart from the material. While oeria files showed tensile stresses under the influence of argon ion bombardment at ambient temperature, they showed a sharp transition from tensile to compressive stress with increase in substrate temperature. When bombarded with oxygen ions they showed a transition from tensile to compressive stress with increase in energy. The titania films deposited with oxygen ions, on the other hand showed purely tensile stresses. Zirconia films deposited with oxygen ions, however, showed a transition from tensile to compressive stress.
PTCDA Films Deposited by Ionized Beam Method
Authors: Usui Hiroaki , Kashihara Kiyoshi , Tanaka Kuniaki , Miyata Seizo
Published: March 2011

Thin films of 3,4,9,10-perylenetetracarboxylic-dianhydride (PTCDA) were deposited by an ionized beam method. The molecular orientation and chemical structure of the films were studied in connection with ionization and ion acceleration conditions. At a low ionization condition, the molecules are oriented in parallel with the substrate, and the crystallinity was improved by an appropriate ion acceleration. At higher ionization conditions, on the other hand, ion acceleration resulted in a loss of crystallinity. Deposited molecules undergo chemical change in such a condition, leading to dissociation of dianhydride groups.
Nucleation and Growth of Cubic Boron Nitride Films Produced by Ion-Assisted Pulsed Laser Deposition
Authors: Friedmann T. A. , Medlin D. L. , Mirkarimi P. B. , McCarty K. F. , Klaus E. J. , Boehme D. R. , Johnsen H. A. , Mills M. J. , Ottesen D. K. , Barbour J. C.
Published: March 2011

We are studying the boron nitride system by using a pulsed excimer laser to ablate from hexagonal BN (hBN) targets to form cubic BN (cBN) films. We are depositing BN films on heated (25 - 800°C) Si (100) surfaces and are using a broad-beam ion source operated with Ar and N2 source gasses to produce BN films with a high percentage of sp3-bonded cBN. In order to understand and optimize the growth and nucleation of cBN films, parametric studies of the growth parameters have been performed. The best films to date show >85% sp3-bonded BN as determined from Fourier-transform infrared (FTIR) reflection spectroscopy. High resolution transmission electron microscopy (TEM) and selected area electron diffraction confirm the presence of cBN in these samples. The films are polycrystalline and show grain sizes up to 30- 40 nm. We find from both the FTIR and TEM analyses that the cBN content in these films evolves with growth time. Initially, the films are deposited as hBN and the cBN nucleates on this hBN underlayer. Importantly, the position of the cBN IR phonon also changes with growth time. Initially this mode appears near 1130 cm-1 and the position decreases with growth time to a constant value of 1085 cm-1. Since in bulk cBN this IR mode appears at 1065 cm-1, a large compressive stress induced by the ion bombardment is suggested. In addition, we report on the variation in cBN percentage with temperature.
Ion-Irradiation-Induced Densification of Zirconia Sol -Gel Thin Films
Authors: Levine Timothy E. , Giannelis Emmanuel P. , Kodali Padma , Tesmer Joseph , Nastasi Michael , Mayer James W.
Published: March 2011

We have investigated the densification behavior of sol-gel zirconia films resulting from ion irradiation. Three sets of films were implanted with neon, krypton, or xenon. The ion energies were chosen to yield approximately constant energy loss through the film and the doses were chosen to yield similar nuclear energy deposition. Ion irradiation of the sol-gel films resulted in carbon and hydrogen loss as indicated by Rutherford backscattering spectrometry and forward recoil energy spectroscopy. Although the densification was hypothesized to result from target atom displacement, the observed densification exhibits a stronger dependence on electronic energy deposition.
Growth of CDTE on GaAs and Si Substrates by Organometallic Vapor Phase Epitaxy
Authors: Bhat Ishwara
Published: March 2011

Epitaxial (100) CdTe layers have been grown by organometallic vapor phase epitaxy (OMVPE) on GaAs and Si substrates. A thin layer of CdTe was first grown by atomic layer epitaxy (ALE) on GaAs substrates followed by thicker CdTe layer by conventional organometallic vapor phase epitaxy (OMVPE). This process resulted in high quality (100) CdTe on GaAs substrates. On Si substrates, direct growth of CdTe resulted in only polycrystalline layers. Hence, a thin Ge buffer layer grown at low temperature followed by an interfacial layer of ZnTe was used to get high quality (100) CdTe on Si. The process developed here eliminates the high temperature (>850°C) deoxidation step generally required when Si substrates are used. The CdTe layers were characterized by X-ray diffraction and optical microscopy. X-ray rocking curve with full width at half maximum (FWHM) of about 260 arcsec has been obtained for a 4 um thick CdTe layer. The results presented demonstrate novel techniques to control the hetero-interfaces in order to grow high quality CdTe on GaAs and Si substrates.
The Effects of Chemical Vapor Cleaning Chemistries on Silicon Surfaces
Authors: Beck S.E. , Gilicinski A.G. , Felker B.S. , Langan J.G. , Bohling D.A. , George M.A. , Tvankovits J.C. , Rynders R.M.
Published: March 2011

This study explores the effects of two chemical vapor cleaning chemistries on silicon surfaces. The silicon surfaces are not significantly roughened by exposure to either process. Trace amounts of fluorine are found on the surfaces exposed to 1,1,1,5,5,5-hexafluoro-2,4-pentanedione (HFAC). A thin silicon nitride film forms on the silicon surface as a result of exposure to the HMDS process and is attributed to the H2/N2 plasma treatment used in the first step of the process.
Surface Cleaning for Silicon Epitaxy Using Photoexcited Fluorine Gas
Authors: Aoyama Takayuki , Yamazaki Tatsuya , Ito Takashi
Published: March 2011

We studied surface cleaning using photoexcited fluorine gas diluted with hydrogen (UV/F2/H2). We found that UV/F2/H2 cleaning selectively removes native Si oxides from thermal oxides without etching the bulk Si. After UV/F2/H2 cleaning, hydrogen atoms terminate almost all the dangling bonds on the Si surface, and fluorine atoms terminate the few remaining bonds. UV/F2/H2 cleaning also flattens the Si surface. We applied UV/F2/H2 cleaning to Si epitaxy and obtained single-crystal Si films with preannealing and growth temperatures as low as 600°C, 150°C lower than for conventional methods. UV/F2/H2 cleaning is a good dry precleaning method for various processes that include Si epitaxy.
Rapid Evaluation of Thin Film Interfacial Reactions Using Temperature-Ramped Measurements
Authors: Harper J.M.E. , Clevenger L.A. , Colgan E.G. , Cabral C. , Arcot B.
Published: March 2011

We describe an approach for rapid evaluation of thin film interfacial reactions using a combination of temperature-ramped in situ measurements of sheet resistance, calorimetry and stress. Electrical, mechanical and thermal measurements at elevated temperatures provide detailed reaction information which is unavailable in room temperature measurements. Kinetic data is particularly useful in making comparisons with mechanistic models. The following examples are discussed:

1. Effects of interfacial oxygen on Ta as a diffusion barrier between Cu and Si,

2. Effects of interfacial oxygen on the Cu/Mg reaction to form CuMg2 and Cu2Mg,

3. Effects of the density of internal interfaces (grain boundaries) on Al2Cu dissolution and precipitation in Al-Cu alloys.
Adhesion Strength of Cu/Polyimide Measured by Continuous Micro-Wedge Scratch Test
Authors: Wang F. , Nelson J.C. , Huang H. , de Boer M. , Gerberich W.W. , Swisher R.L.
Published: March 2011

A modified form of nanoscratch test, continuous micro-wedge scratch technique was applied to characterize the adhesion strength of 0.2 μm thick, 10 μm width sputtered copper fine lines on 50 μm thick solid PMDA-ODA polyimide films. A 20 μm width wedge-shaped diamond tip was used to mechanically debond Cu fine lines to polyimide substrate. Using a microindenter under control depth testing mode, critical loads for delaminations were obtained. The scratch morphology and the debonded areas were observed by scanning electron microscopy. The scratch test results by conical-shaped tip on plain films are also presented here and are compared to the results by wedge-shaped tip in fine metal lines. Practical work of adhesion of 4.1 J/m2 was calculated by FEM based on bimaterial fracture mechanism
Processing High Quality Toughened Zirconia Ceramics by Controlling the Chemistry at the Particle-Particle Interface
Authors: Thuraisingham S.T. , Henshall J.L.
Published: March 2011

A novel lower cost wet-processing technique, for producing toughened zirconia ceramics with complex geometries, is presented. It is based mainly on modifications to the particle surface chemistry. The sintered materials produced so far are significantly harder (ca 50%) as well as being tougher (ca 10%) than a commercial CeTZP.
Structural and Film Stress Investigation of the Interfacial Reaction in Al/SiC Microlaminates
Authors: Inturi R. B. , Chinmulgund M. , Shamsuzzoha M. , Barnard J. A.
Published: March 2011

The effect of laminate geometry and thermal treatment on the microstructural evolution of interfacial reaction products and thin film stress in Al/SiC microlaminates has been investigated by x-ray diffraction, transmission electron and optical microscopy, and thin film stress measurements. Both stress-temperature and stress-time studies are conducted. Crystalline Si of two dimensional ‘dendritic’ morphology is observed as a solid state reaction product at the Al/SiC interface following an anneal at 400 °C. This interfacial reaction is associated with a sharp change in thin film stress in laminates with very thin AI layers to a highly compressive state during isothermal annealing at 400 °C of as-deposited laminates. The change in film stress state is in agreement with the expected larger molar volume of the likely product phases.
Surface Steps on (100) MgO Foils Imaged by TEM, SEM and AFM
Authors: King Simon , Heffelfinger Jason , Mallamaci Michael , McKernan Stuart , Carter C. Barry
Published: March 2011

The morphology characteristic of acid-washed and annealed MgO (100) surfaces used as substrates for pulsed-laser deposition (PLD) is studied employing TEM, SEM and AFM. Each of these three microscopal techniques provides information not so readily accessible by and complementary to the other two techniques, leading to a more rounded view of the characteristic morphology of these surfaces.
Ionic Conduction Mechanisms in CaF2 and CaF2-Al2O3 Nanocomposite Films on Al2O3 Substrates
Authors: Modine F. A. , Lubben D. , Bates J. B.
Published: March 2011

Thin films of pure CaF2 and nanocomposite mixtures of Al2O3 with CaF2 were sublimated on Al2O3 substrates. Interdigital electrodes allowed in situ measurements of the electrical conduction of films as a function of thickness, deposition rate, composition, time, and temperature. The electrical conductivity in pure CaF2 adjacent to an Al2O3 interface sometimes exceeded the bulk CaF2 conductivity (i.e., value at more than 50 nm distance) by as much as a factor of 6700 at 200°C. The high conductivity is characterized by an activation energy of 0.6 ± 0.1 eV, which is significantly lower than the activation energy of about 1.0 eV for conduction in the bulk. However, this high conductivity is thermally unstable and diminishes in time. A high but stable conductivity was obtained in CaF2 films containing about 10 mole percent Al2O3 as a dispersed second phase. At 200°C, a 2-phase film gave a factor of 360 enhancement over the measured bulk CaF2 conductivity and a factor of 7 improvement over the best previously reported conductivity for CaF2-Al203 composite materials. The origin of enhanced conduction in CaF2 is attributed to ion transport along dislocations. Dislocations anneal with a characteristic log of time dependence that is recognizable in the annealing behavior of the electrical conductivity. Presumably, the addition of a dispersed second phase of Al2O3 to CaF2 serves both to generate and to pin dislocations; the electrical conductance is thereby enhanced and stabilized.
The Surface Morphology of Titanium Nitride / Copper Bilayers Annealed at High Temperatures
Authors: Berti Antonio C. , Murarka Shyam P. , Brooke Laura E.
Published: March 2011

Bilayers of 40 nm titanium nitride and 500 nm copper were sputter deposited on oxidized silicon substrates. The films were annealed for one hour at temperatures from 400° C to 800° C in either vacuum or Ar/H2, ambients. Neither x-ray diffraction or Rutherford backscattering spectrometry indicated any interaction between the titanium nitride and copper films. While no differences in surface morphology were detected at annealing temperatures of less than 500° C, above this temperature a strong dependence on annealing ambient was found. In the vacuum annealed samples, surface grooves formed at the grain boundaries of the copper film. These grooves became progressively larger as the annealing temperature was increased, eventually leading to void formation. Only small grain boundary grooves were present in the Ar/H2, annealed films regardless of annealing temperature. The driving force for the formation of the grooves is believed to be a difference between the grain boundary and surface energies in the copper films. It is speculated that in Ar/H2 anneals this driving force is reduced because hydrogen segregates to the copper grain boundaries and lowers the grain boundary energy.

The formation of grooves was found to retard copper grain growth and texturing. Resistivity of the copper film was also found to increase if the void density was sufficiently high.
Ultraviolet (UV) Irradiation Effect on Minority-Carrier Recombination Lifetime in Silicon Wafers with Oxide and Nitride Films
Authors: Zhong L. , Shimura F.
Published: March 2011

A new method based upon photoconductance measurement of the minority-carrier recombination lifetime is developed to investigate defects both in dielectric films and on the interface. In this method, surface recombination process in silicon substrate is used as a probe to detect the interface traps generated by ultraviolet (UV) irradiation as well as the defects in a film whose electronic state can be excited by UV irradiation. A variety of films, including native, chemical vapor deposited (CVD) and thermal oxide as well as CVD nitride, have been studied. In CVD nitride, for example, evidence is provided that K-centers, the main charge trapping defects, have a negative correlation energy (negative-U).
Back-Channel Surface Modifications for a-Si:H Thin Film Transistors, TFTs, by Exposure to Plasma Excited N2O
Authors: He S.S. , Stephens D.J. , Lucovsky G.
Published: March 2011

We have studied different surface treatments for the back side of the channel of bottom gate a-Si:H TFTs. Two sets of different (i) channel layer thicknesses, and (ii) gate dielectric silicon nitride compositions were studied. The back channel Si-surfaces were either (i) exposed to products from an N2O plasma, or (ii) plasma oxidized. Comparisons of these back channel passivation methods indicated that relative to oxidized surfaces, the plasma N2O process, which created an oxynitride surface layer, (i) reduced the threshold voltage, (ii) decreased the sub-threshold slope (defined as V/decade of current increase) of the I-V characteristic, and (iii) increased the transconductance, or equivalently, the effective channel mobility.
Finite-Temperature Molecular Dynamics Study for Atomic Structures of Grain Boundary in Transition Metals Fe and Ni
Authors: Chongyu Wang , Wenhui Duan , Quanming Song
Published: March 2011

Based on Gauss’ principle of least constraint and Nosé-Hoover thermostat formulation, the numerical algorithms for molecular dynamics simulation are developed to investigate the properties of grain boundary in transition metals Fe and Ni at finite temperature. By the appropriate choice of heat bath parameter, a constant temperature version can be realized. A series of parameters are introduced to describe quantitatively the crystallographic characteristic and the distortion of structure unit. The results indicate the applicability of the calculation mode developed by us and reveal the feature of the atomic structure of grain boundary at finite temperature.
Surface Hardening of Ceramic Oxide and Metal Alloy Single Crystals by Ultrasonic Cavitation
Authors: Brewster James R. , Powell-Friend Y. , Boatner L. A.
Published: March 2011

Cavitation effects have long been considered to be undesirable phenomena that resulted in the damage and failure of metallic components. In the present work, we establish that, in fact, controlled applications of ultrasonic cavitation phenomena can be used to enhance the surface properties of both ceramics and metals. Polished (100) surfaces of single-crystal MgO and single crystals of 70%Fe-15%Ni-15%Cr (stainless-steel) were subjected to ultrasonically induced cavitation by exposure to 20 kHz excitations (at ∼ 100 W/cm2) in isopropanol. Knoop micro-indentation hardness measurements on untreated and ultrasonically treated areas of the surfaces revealed a hardening that increased with the duration of the ultrasonic treatment up to a saturation level. Relative increases in the surface hardness of up to 30% in the case of MgO and ∼250% in the case of Fe-Ni-Cr were obtained. It was found that the rate of hardening was not uniform over the surface but was more rapid on those portions of the surface that were directly under the edge of the ultrasonically vibrating horn tip.
Fabrication and Characterization of MgO Bicrystals
Authors: Liberatore Michael , Wuensch B.J. , Solorzano I.G. , Sande J.B. Vander
Published: March 2011

High purity bicrystals of MgO have been grown using chemical vapor transport for the purpose of studying oxygen grain boundary diffusion. Preliminary data indicate preferential diffusion of oxygen along ∑ 13 symmetric tilt boundaries. The measured grain boundary diffusivities were approximately 4 orders of magnitude higher than the corresponding bulk values. The activation energies for bulk and grain boundary diffusion were found to be equal to within experimental error, (≈3.9eV)
Annealing Effects to Electrode Pt / Ti for PZT
Authors: Numata Ken , Aoki Katsuhiro , Fukuda Yukio , Nishimura Akitoshi
Published: March 2011

The application of ferroelectrics such as SrTiO3 or PbZrxTi(1−x)O3 to the insulator of DRAM cell capacitors has been extensively studied. The bottom electrode Pt / Ti for these ferroelectrics needs to be thermally stable because of the crystallization process of ferroelectrics. By varying the annealing temperature from 400°Cto 800°C, we examined the annealing effects to the electrode Pt / Ti by SEM, TEM and in-situ XRD.
Super-Amorphous Alumina Gels
Authors: Pierre A. C. , Uhlmann D. R.
Published: March 2011

The structures of alumina gels made from aluminum sec butoxide have been studied by X-ray diffraction and scanning electron microscopy as a function of pH as well as of the temperature of peptization and gelling. The structures of these gels appear to be very sensitive to the conditions of preparation, and lead to a variety of gelled products and transformation behaviors on firing. Specific attention is directed to preferential orientation and to structures which are X-ray super-amorphous.
Design and Synthesis of Metal-Organic Precursors to Aluminosilicates
Authors: Williams Arlene G. , Interrante Leonard V.
Published: March 2011

Diketonate aluminum alkoxides were prepared and allowed to react with acetoxyalkylsilanes. The conversion of the aluminosiloxanes thus obtained to aluminosilicates at 450°C was demonstrated. These aluminosiloxane ceramic precursors are glassy, oligomeric materials which readily dissolve in organic solvents to give viscous solutions ideal for casting films. Films of the metal-organic compounds prepared in this manner yield monolithic, crack-free aluminosilicate films directly on thermal curing, with a thickness limit of 3000Å for single crystal silicon wafer substrates. These aluminosilicate films have been found to be effective anticorrosion barriers for various metal substrates. The chemistry of this organoaluminosilane system and the nature of the aluminosilicate films obtained has been investigated using a variety of chemical and physical methods. The results of this investigation will be described and the possible advantages of this direct conversion process over the sol-gel method as a means of obtaining aluminosilicate films will be discussed.
Avoiding Ceramic Problems by the Use of Chemical Techniques
Authors: Morgan Peter E. D.
Published: March 2011

As the title of this meeting suggests, a paradigm change is underway in the ceramic community; methods of synthesis and use of ceramic powders are being hurriedly reappraised. The imperative for change was all in place by an important meeting that took place in 1977 [1].
Precursor Chemistry Effects on Development of Particulate Morphology During Evaporative Decomposition of Solutions
Authors: Gardner Timothy J. , Sproson D. W. , Messing G. L.
Published: March 2011

Fine-grained, high surface area MgO, NiO and ZnO powders were synthesized by the evaporative decomposition of solutions (EDS) technique at 1000°C from acetate and nitrate salt solutions. The powder characteristics were similar in all cases; however, aggregated powders were obtained from the nitrate salts and aggregate-free powders were obtained from the acetate solutions when reacted in air. This difference is attributed to the oxidation of the acetate radical and/or its residue and that this process acts to disaggregate the salt droplet/particles that are formed during EDS.
An Infrared Study of Metal Isopropoxide Precursors for SrTiO3
Authors: Riman R. E. , Haaland D. M. , Northrup C.J.M. , Bowen H. K. , Bleier A.
Published: March 2011

A Sr/Ti bimetallic isopropoxide complex was synthesized by two methods. The complex served as a precursor to the production of homogeneous SrTiO3 powders via alkoxide hydrolysis. Infrared spectra were obtained for Sr(OPri)2, Ti(OPri)4, and the product of the syntheses. In addition, the IR spectra of the solutions of each of the alkoxides were followed as hydrolysis reactions proceeded. Detailed analysis of the spectral features support the existence of a 1:1 Sr/Ti bimetallic alkoxide. The new Sr/Ti compound exhibits characteristic absorption bands at (1017, 993, 972, 961 cm−1), (844, 838, 827 cm−1) and (620, 596, and 572 −1). A band at 819−1 might also be associated with the new Sr/Ti bimetallic alkoxide. The infrared spectra suggest that the isopropoxide ligands in the bimetallic alkoxide are in at least three separate local environments. This information offers insight into possible structures for the complex.
The Processing and Characterization of DCCA Modified Gel-Derived Silica
Authors: Wallace S. , Hench L. L.
Published: March 2011

The production of small silica gel monoliths by the hydrolysis and polycondensation of tetramethyl orthosilicate (TMS) in a methanol solution is now a common procedure. Drying is generally done slowly in a methanolic atmosphere [1] or under hypercritical conditions [2]. The potential application of sol-gel technology in the production of materials for large structures requires a rapid processing time, which causes a problem due to cracking. For large scale space structures the materials produced also require a low molecular weight, a low densification temperature, control of devitrification and a wide range of physical properties and gel densities. These requirements are potentially met by multicomponent silica based gels [3]. To decrease the drying time, which is the longest part of gel processing, the gel strength needs to be increased to resist cracking and the drying stress reduced. The gel strength can be improved by optimizing the variables in the gel manufacturing process.
Processing and Properties of Sol-Gel Derived 20 Mol% Na2 0–80 Mol% SiO2 (20N) Materials
Authors: Wang S. H. , Hench L. L.
Published: March 2011

A number of investigators [1–6] have studied the sol-gel-glass transformation and the aging, drying and densification processes involved. However, monolithic, amorphous, large scale xerogels are still difficult to produce because of insufficient understanding of basic changes in microstructure during the sol-gel-glass transformation and the chemical reactions of the precursors, solvents and catalysts used. Some papers sugqest ways of obtaining monolithic gels by (1) increasing the mechanical strength of gel by aging [7]; (2) diminishing the magnitude of capillary forces by enlarging the pore size and/or decreasing the surface energy by using surfactants [8] (3) reducino the rate of evaporation of the solvent from the pores by using a semipermeable membrane during drying [9] (4); and eliminating the pore liquid-solid interface by hypercritical evacuation [10].
Physical-Chemical Variables in Processing Na2O - B2O3 - SiO2 Gel Monoliths
Authors: Orcel Gerard , Hench Larry L.
Published: March 2011

The addition of a dryinq control chemical additive (DCCA) to the solvent allows short drying times for monolithic gel samples. The variables involved in the use of a DCCA in preparing gels from the Na2O-SiO2 -B2O3 system are described. Due to its higher reactivity, a DCCA influences the chemical behavior of the material at each step of the processing. The effects of formamide as a DCCA on the qelation process, surface charge, and surface area are presented. The variations of the physical properties of the gel, due to the addition of the DCCA, are related to the reactions of the formamide with the sol. Although the DCCA helps in producing monolithic dried gels, the problem of densification is not solved as yet.
The Role of Water in Densification of Gels
Authors: Gallo T. A. , Brinker C. J. , Klein L. C. , Scherer G. W.
Published: March 2011

The densification behavior of a gel-derived borosilicate glass was studied. Surface area, thermal gravimetric and infrared measurements were used to calculate the surface hydroxyl coverage as a function of time at several temperatures. Application of a viscous sintering model to the isothermal shrinkage data showed viscosity to increase isothermally by almost two orders of magnitude at the lowest investigated temperature. Although most of this increase is attributable to increased crosslinking accompanying dehydroxylation, structural relaxation was also shown to significantly affect the densification kinetics.
X-RAY and Electron Diffraction Studies of AS-Deposited rf Sputtered Thin Films of lrO2
Authors: Penfold I. T. , Moss S. C. , Kulik J. , Kreider K. G.
Published: March 2011

Iridium oxide films produced by reactive sputtering (SIROFs) have considerably higher densities than those made by other techniques such as the anodic reaction at metal surfaces which contain pores and Microvoids. It has been previously reported that SIROFs deposited with substrate temperatures of 300K are amorphous. Here we report x-ray and electron diffraction measurements on SIROFs deposited on Al2O3, Si, NaCI and MgO substrates at 40°C. The x-ray diffraction patterns, I(Q), show “diffuse” structure that extends to beyond Q(=4εsinθ/) =10Â−1. We show that it is possible to reproduce qualitatively the main features of the diffraction pattern by convolving the crystalline rutile powder pattern with a Lorentzian profile. The width of this profile is compatible with that determined from the Scherrer equation although significant peak shifts and texture are observed. This analysis reveals that as-deposited SIROFs are crystalline with particle sizes in the range 25À to 35Å rather than amorphous (for which no crystalline model would be appropriate). The electron microdiffraction data are also consistent with a crystallite size of a few nm and high resolution TEM reveals lattice fringes from crystallites few nm in size. The peak shifts, however, remain to be explained.