bluuebunny/crossref_metadata_2025_split huggingface dataset:
Nanoscale/Multilayer Gradient Materials for Application in the Electromagnetic Gun Systems
Authors: Otooni M.A. , Brown I.G. , Anders S. , Wang Z. 
Published: April 2011

AbstractAnalysis of fired rails from electromagnetic railguns indicates severe surface damage occurs due to high current arcing and tribological mismatch. We have explored the behavior of several nanoscale multilayered materials as possible routes to improve the thermomechanical properties of the rail and armature materials . Structures investigated include (i) Ti-Co alloy on Ta-Cu alloy on dlc (diamond-like carbon) on stainless steel; (ii) Ti-Co alloy on Ta-Cu alloy on dlc on Cu, (iii) Ti-Co alloy on Ta-Cu on Cu; and (iv) Ti-Co on Ta-Cu alloy on Al. The alloys were all 50:50 at% and film thicknesses were in the range 400-1000 Å. The films were formed using a repetitively pulsed vacuum arc plasma deposition method with substrate biasing- and IBAD-like techniques. The surfaces were characterized by scanning electron microscopy, transmission electron microscopy, Rutherford backscattering spectroscopy, optical microscopy, microhardness measurements, arc erosion resistance and scratch resistance tests. Preliminary results show improvement in the microhardness, arc erosion resistance and scratch resistance, most especially for the dlc-coated surfaces. This kind of multilayered approach to the fabrication of electromagnetic railgun and armature surfaces could be important for future advanced Electromagnetic EM Gun systems.
Friction Change Induced by Single Mev Ion Impact Measured by Scanning Probe Microscope
Authors: Ogiso Hisato , Nakano Shizuka , Tokumoto Hiroshi , Yamanaka Kazushi 
Published: April 2011

AbstractIn order to evaluate the damage caused by a single MeV ion impact, we prepared highly oriented pyrolytic graphite specimens, each implanted with 3.1 MeV Au, Ag, Cu and Si ions at a dose of 2.3×1011 cm-2 (2300 μm-2). We then observed specimens by using friction force microscope, and found round regions caused by single-ion impacts on the implanted surface. The frictional force between the surface and the silicon-nitride tip increased in disordered regions. The number density of the regions differed at individual ion-implanted surface, and was about 1000 μm-2 at the Au-implanted surface, 880 μm-2 at the Ag-implanted surface, 372 μm-2 at the Cu-implanted surface, and 44 μπτ2 at the Si-implanted surface. We calculated the electronic stopping power and the probability of knock-on atom generation by the nuclear collision to determine which process affected the density. We found that the difference in the number density was closely related to that of nuclear collisions.
High Conductivity FIB Deposited Metal
Authors: Blauner P.G. , Wagner A. 
Published: April 2011

AbstractThe ion beam induced metal deposition processes now employed by commercial focused ion beam (FIB) tools all demonstrate less than optimal characteristics for use in circuit repair, a major application of these tools. In particular, the processes have low efficiencies, the metals produced have poor conductivity, and some form of clean up is generally required to remove excess material surrounding the repair site. The gold deposition process developed for x-ray mask repair, in contrast, exhibits efficiencies 10-50 times higher with significantly less material deposited in unwanted areas. Unfortunately, the conductivity of the gold is even poorer than that of materials now used for FIB circuit repair.In this paper, an annealing step which improves the conductivity of FIB deposited Au is described. Results are presented demonstrating resistivities of 5-15 μΩ-cm while maintaining the high efficiency of the gold deposition process. The suitability of the process for use in FIB circuit repair is discussed.
The Detailed Dependence of Implanted Phosphorus Profiles in (100) Single-Crystal Si on Key Implant Parameters
Authors: Ghante V. , Lam L. M. , Morris S. , Yang S.-H. , Tasch A. F. , Kamenitsa D. , Sheng J. , Evans C. , Magee C. 
Published: April 2011

AbstractThe continued decrease in semiconductor device feature size has required much smaller thermal processing budgets in order to achieve the required compact doping profiles. As a result, the impurity profiles have a larger dependence on the ion implant parameters, and more attention must be given to minimizing channeling, which results in deeper implanted profiles. Thus, there is a need for a detailed understanding of the dependence of the implanted profile on the key implant parameters. Since such an understanding does not exist for phosphorus implants in silicon, a detailed study has been performed by obtaining experimental phosphorus impurity profiles for a wide range of implant energies (15 - 180 keV), doses (lx1013- 8×1015 cm–2), tilt angles (0° - 10°), and rotation angles (0° - 360°). Channeling along the <100 axial channel dominates the variations. (110) planar channeling is the next most important channeling effect, appearing at higher (5°) tilt angles, where <100 axial channeling is suppressed. (100) planar channeling is not observed at the lower energies but does manifest itself for energies of 80keV and greater. Dose dependencies play a large role beginning around lxlO14 cm-2.
Afm Study of Surface Morphology of High Dose Co Implanted Si with A Mevva Ion Source
Authors: Peng Qicai , Wong S.P. , Xu J.B. , Wilson I.H. 
Published: April 2011

AbstractThe surface morphology of high dose Co implanted Si has been studied by atomic force microscopy. The Co implantation was performed using a metal vapor vacuum arc (MEVVA) ion source at an extraction voltage of 60 or 70 kV to a dose of 2×l017 or 4×l017 ions cm-2 at substrate temperatures Ts ranging from 210°C to 700°C. When Ts is less than about 600°C, the surface morphology of the implanted samples shows largely similar features of densely distributed narrow asperities. However, for the sample with Ts of 700°C, the surface morphology is significantly different and shows hillocks of much larger size. It is also found that when other parameters are fixed, for Ts less than about 600°C, the root-mean-square roughness Rrms increases exponentially with 7^, from the subnanometer scale to several nanometers. But for the sample with Ts of 700°C, there is an abrupt increase in Rrms to 35 nm. The variation of the surface morphology with other parameters is also discussed.
Low Temperature Phase Transition (Pt) and Defect Formation (Df) in Silicon with Dioxide Inclusions Under X-Ray Irradiation
Authors: Makhkamov SH.M. , Abdurakhmanova S.N. 
Published: April 2011

AbstractStudies of galvanomagnetic and electrical parameters of p- type Si : SiO2 in the temperature range 80 – 400 K have shown that X-ray irradiation at 80 K (Mo Ka,β and braking radiation hvmax. = 50 heV) leads to various transformations of the spectrum of electron- hole states in the band gap of such material, depending on the flux density of the X-rays. Two main processes are observed: the defect (vacancy and divacancy) formation and a charge exchange of native defects localized at the Si – SiO2 interface. The charge exchange process is rather collective and stimulated one because it is in response to an X-ray-induced ferroelectric phase transition in the SiO2- phase.
Irradiation-Induced Damage and Intermixing of GaAs-Algaas Quantum Wells
Authors: Tan H.H. , Williams J.S. , Jagadish C. , Burke P.T. , Gal M. 
Published: April 2011

AbstractA comparison of ion irradiation-induced intermixing in GaAs-Al0.54Gao46As quantum well structures with H, O and As ions is investigated by low temperature photoluminescence. Very large energy shifts are observed together with good recovery of the photoluminescence intensities after annealing in samples irradiated with protons. No saturation in the energy shifts is observed in samples irradiated even up to a dose of 4.3 x 1016 cm-2. Similar large shifts with low absorption are also observed in O and As implanted samples but at a significantly lower ion dose. However, both the heavier ions show a saturation effect in the degree of intermixng at higher doses. The degree of intermixing is believed to be a delicate balance among multiple competing processes that occurs across the interface.
Dose and Doping Dependence of Damage Annealing in Fe Mev Implanted Inp
Authors: Carnera A. , Fraboni B. , Gasparotto A. , Priolo F. , Camporese A. , Rossetto G. , Frigeri C. , Cassa A. 
Published: April 2011

AbstractHigh energy (2 MeV) ion implantation of Fe in InP has been investigated by means of Rutherford backscattering spectrometry (RBS), transmission electron microscopy (TEM) and secondary ions mass spectrometry (SIMS). The implanted doses ranged between 5×l013 and 5×l014 at/cm2. Annealing in the 650–800 °C range was performed and the primary as well as secondary damage evolution has been studied. The correlations between defect structure and Fe redistribution properties have been carefully analysed. The results show the role of the primary defect structure in determining the annealing properties, both for damage recovery and Fe redistribution. The latter is also influenced by the doping of the substrate.
Enhancement of the Adhesion of Beryllium Films with Interfacial Beo to Carbon Substrates
Authors: Musket R.G. , Wirtenson G.R. 
Published: April 2011

AbstractWe have used 200 keV carbon ions to enhance the adhesion of 240-nm thick Be films to polished, vitreous carbon substrates. Adhesion of the as-deposited films was below that necessary to pass the scotch-tape test, but carbon ion fluences less than 1.6xl014 C/cm2 were sufficient to ensure the passage of the tape test without affecting the optical properties of the films. Adhesion failure of the as-deposited film was attributed to an inner oxide layer between the Be and the carbon. Because this oxide (-5 nm of BeO) was not measurably changed by the irradiation process, these results are consistent with adhesion enhancement occurring on the atomic scale at the interface between the inner oxide and the carbon substrate, and this conclusion was supported by Rutherford backscattering (RBS) data. Potential adhesion mechanisms are discussed with consideration of relative contributions from electronic and nuclear stopping.
Structural and Ferroelectric Properties of Epitaxial La0.5Sr0.5CoO3/Ba0.4Sr0.6TiO3/La0.5Sr0.5CoO3 Thin-Film Capacitors on Silicon for Dram Applications
Authors: kung Pang-Jen , Fenner David B. , Li Qi 
Published: April 2011

AbstractEpitaxial La0.5Sr0.5CoO3/Ba0.4Sr0.6Tio3/La0.5Sr0.5CoO3 heterostructures were grown (650- 750 °C) on yttria-stabilized zirconia (YSZ)-buffered silicon (100) by pulsed laser (Nd:YAG) deposition. A 15-nm-thick YBa2Cu3O7 film was deposited on the YSZ to act as a template layer for epitaxial growth of the subsequent conductive oxide and ferroelectric film layers. The Ba0.4Sr0.6TiO3 film was (h00) oriented normal to the Si-wafer surface. The temperaturedependent resistance curve measured on the La0.5Sr0.5CoO3 top electrode layer was found to indicate to some extent the film quality of the underlying layers. Hundreds of capacitors, fabricated by wet chemical etching from the as-deposited films, exhibited dc leakage current densities in the range of 0.05–0.1 μA/cm2 at 1-volt operation. By increasing the thickness of the dielectric layer, some of them were able to be tested at up to 20 volts before resistive leakage became dominant. To reduce leakage current densities and increase dielectric constants in these film capacitors for dynamic random access memory (DRAM) applications, we have made efforts to incorporate hybrid Pt/La0.5Sr0.5CoO3 bottom electrodes into capacitors. This results in improved dielectric constants (451 at 10 kHz) and P-E hysteresis characteristics (Ec = 58 kV/cm, Pr = 7.5 μC/cm2, and Pg = 25 μC/cm2).
Homoepitaxial and Heteroepitaxial Growth of Sr0.61Ba0.39Nb2O6 Thin Films by Pulsed Laser Deposition
Authors: Yeo J. S. , Youden K. E. , Huang T. F. , Hesselink L. , Harris J. S. 
Published: April 2011

AbstractEpitaxial SBN:61 films have been grown on SBN:75 and MgO substrates by pulsed laser deposition. The optical loss due to absorption is greatly reduced by increasing the oxygen pressure to 1 mbar during the cooling process. In homoepitaxy, X-ray phi scans on the (221) plane of the SBN:61 films indicate that the in-plane grains are rotated 0° or ±28° with respect to single crystalline SBN:75 substrates. Cross-section and plane view high resolution TEM reveals this crystalline relations and microstructure of SBN thin films. Pr doped SBN:61 thin films show sharp transition band at 495 nm and 607 nm in room temperature photoluminescence measurement.
High Temperature Superconducting Step-Edge SNS Josephson Junctions on Silicon Substrates
Authors: Rosenthal P. A. , Cosgrove J. E. , Fenner D. B. , Vale L. R. , Ono R. H. , Rudman D. A. 
Published: April 2011

AbstractWe have fabricated and tested YBCO step-edge SNS Josephson junctions on silicon substrates. The silicon step edges were patterned photolithographically and reactively ion etched using an SF6 plasma. The structures were fabricated through sequential angled pulsed laser deposition of yttria stabilized zirconia, YBCO, and gold layers, followed by photolithographic patterning and ion milling. The completed devices showed resistively shunted junction (RSJ)-like current voltage characteristics and microwave induced Shapiro steps. Critical currents as large as 84 PA and resistances of order 0.5 Ω were obtained. Measurable critical currents were observed up to 76 K. We report on the fabrication and properties of these junctions.
The Influence of Weak Links and Oxygen Deficiency on Electrical Properties of Bi-2212 and Ti-2212 Hts Thin Films
Authors: Schindler Jon L. , Dimeo Frank , Duran Carolyn R. , Hinds Bruce J. , Wessels Bruce W. , Marks Tobin J. , Kannewurf Carl R. 
Published: April 2011

AbstractThin films of the Bi-2212 and T1–2212 compounds were prepared by MOCVD deposition techniques. Resistivity versus temperature and critical current density measurements were used to characterize the electrical properties. An analysis of the data based on a proposed model determined the influence of intragranular weak links. Thin film samples in both systems with near optimum oxygen doping showed a correlation between the slope and magnitude of the resistivity in the normal state. Samples with reduced oxygen content displayed a strong increase in the intragrain boundary resistance, consistent with weak link defects. The results agree with a similar analysis of YBCO samples and support a common mechanism for the development of weak links in cuprates.
The Function of Buffer Layers and Defects in Heteroepitaxial BaxSr1-xTiO3/YBa2Cu3O7-x/CeO2/Y-ZrO2/Si/Al2O3 Multilayers
Authors: Olsson E. , Boikov Yu. , Ivanov Z. G. , Vasiliev A. L. , Claeson T. 
Published: April 2011

AbstractDifferent aspects of interfacial interactions during the growth of epitaxial oxides are illustrated in a BaxSr1-xTiO3/YBa2Cu3O7-x/CeO2/Y-ZrO2/Si/Al2O3 heteroepitaxial multilayer. The effect of chemical interaction, interdiffusion, epitaxial strain and thermal strain are exemplified. It is shown how buffer layers can be used to compensate for otherwise detrimental interactions. Considerations necessary for annealing following the film depositions are also addressed. Even if the described structures are specific for this system, similar considerations need to be made for other oxide systems as well. The present description can provide help to identify suitable material combinations.
Investigation of Cation Disorder In ‘C’ Axis Ybco 123 Thin Films Using Raman Microscopy
Authors: Cohen L. F. , Li Y. B. , Gibson G. , MacManus-Driscoll J. 
Published: April 2011

AbstractTwo 123 thin films grown by e-beam evaporation have been studied using Raman microscopy. The films were grown under different conditions of temperature and oxygen partial pressure and show different levels of cation disorder as determined from the ‘c’ axis lattice parameter in combination with x-ray data. The oxygen stoichiometry in each film was changed by controlled anneals using a coulometric titration apparatus. As a result we report on the sensitivity of the 500cm−1 and 585cm−1 Raman peak to the oxygen stoichiometry and how the intensity and position of these peaks can be used to detect or confirm the presence of a small amount of cation disorder.
Epitaxial Growth of γ -Al2O3 Insulator Films on Si by Molecular Beam Epitaxy Using an Al Solid Source and N2O Gas
Authors: Wado H. , Shimizu T. , Ohtani K. , Jung Y. C. , Ishida M. 
Published: April 2011

AbstractHigh quality crystalline γ -Al2O3 films were epitaxially grown on Si(111) substrates at growth temperatures from 750 to 900°C by molecular beam epitaxy using an Al solid source and N2O gas. Very thin γ -Al2O3 films grown at a growth temperature of 850°C showed streaky reflection high-energy electron diffraction patterns. By in situ x-ray photoelectron spectroscopy measurements, carbon contamination, as is seen in the films grown with a Al(CH3)3 source, was not detected within the measurement sensitivity. The stoichiometry of the grown film was found to be similar to that of Al2O3. Growth rates of epitaxial γ -Al2O3 layers decreased with increasing growth temperatures. The predominant growth of the γ -Al2O3(111) crystal orientation was confirmed on Si(110) and Si(100) substrates.
Growth of Epitaxial a-Axis and c-Axis Oriented Sr2RuO4 Films
Authors: Madhavan S. , Gibbons B. J. , Dabkowski A. , Dabkowska H. A. , Trolier-Mckinstry S. , Liu Ying , Schlom D. G. 
Published: April 2011

AbstractEpitaxial films of Sr2RuO4 have been grown in situ by pulsed laser deposition on (100) LaAlO3 and (100) LaSrGaO4 substrates. X-ray diffraction results show that the films are single domain and grow c-axis oriented on (100) LaAlO3 and a-axis oriented on (100) LaSrGaO4 substrates. X-ray ø-scans indicate epitaxial alignment of the film and substrate in-plane axes in both cases. Resistivity versus temperature measurements reveal that the as-grown c-axis oriented films are semiconducting and the a-axis oriented films are metallic. The metallic films grown so far were found to be non-superconducting down to 50 mK.
Epitaxial Single Crystalline Ferrite Films for High Frequency Applications
Authors: Suzuki Y. , Dover R. B. Van , Korenivski V. , Werder D. , Chen C. H. , Felder R. J. 
Published: April 2011

AbstractThe successful growth of single crystal ferrites in thin film form is an important step towards their future incorporation into integrated circuits operating at microwave frequencies. We have successfully grown high quality single crystalline spinel ferrite thin films of (Mn, Zn)Fe2O4 and CoFe2O4 on (100) and (110) SrTiO3 and MgAl2O4 at low temperature. These ferrite films are buffered with spinel structure layers that are paramagnetic at room temperature. In contrast to ferrite films grown directly on the substrates, ferrite films grown on buffered substrates exhibit excellent crystallinity and bulk saturation magnetization values, thus indicating the importance of lattice match and structural similarity between the film and the immediately underlying layer. X-ray, RBS, AFM and TEM analysis provide a consistent picture of the structural properties of these ferrite films. We then use this technique to grow exchange-coupled bilayers of single crystalline CoFe2O4 and (Mn, Zn)Fe2O4. In these bilayers, we observe strong exchange coupling across the interface that is similar in strength to the exchange coupling in the individual layers.
The Effect of Oxygen Deposition Pressure on the Structure and Properties of Pulsed Laser Deposited LaxCa1−xMnOδ Films
Authors: Horwitz J. S. , Dorsey P. C. , Koon N. C. , Rubinstein M. , Byers J. M. , Gillespie D. J. , Osofsky M. S. , Harris V. G. , Grabowski K. S. , Knies D. L. , Donovan E. P. , Treece R. E. , Chrisey D. B. 
Published: April 2011

AbstractThin films (∼1000 Å) of LaxCa1−xMnOδ (x=0.67) were deposited onto LaA1O3 (100) substrates at of 600 and 700°C. Varying the oxygen deposition pressure between 15 and 400 mTorr systematically changed the oxygen concentrations in the as deposited films. Asdeposited films exhibited an orthorhombic structure with an oxygen pressure dependent lattice parameter. The films were highly oriented as characterized by narrow x-ray ω-scans (FWHM ≤ 0.16 −0.70°). At low pressures, the films were preferentially (202) oriented while at high pressures deposited films had a (040) preferred orientation. A 900°C anneal in flowing oxygen for a film deposited at low oxygen pressures resulted in a decrease in the lattice parameter (associated with an increase in δ) and a change in the preferred orientation from (202) to (040). The resistivity as a function of temperature (R(T)) showed a significant variation as a function of growth conditions. At 600°C, the peak in the resistivity curve (Tm) varied between 73 and 93 K for P(O2) = 15 to 400 mTorr, while at 700°C, Tm was ∼150 K. For films deposited at 600°C, the resistivity was reduced by a factor of 103 for H = 9T and Tm was shifted to 150 K. The activation energy associated with the semiconducting phase was approximately the same for all as-deposited films (∼100 meV).
Intrinsic Properties of Doped Lanthanum Manganite
Authors: Snyder G. Jeffrey , Hiskes Ron , DiCarolis Steve , Beasley M. R. , Geballe T. H. 
Published: April 2011

AbstractAn investigation designed to display the intrinsic properties of perovskite manganites was accomplished by comparing the behavior of bulk samples with that of thin films; the results show the "colossal magneto resistance" at very low temperatures is not an intrinsic property of the thermodynamically stable 1/3 doped material. Epitaxial 1500 Å films of perovskite La0.67Ca0.33MnO3 and La0.67Sr0.33MnO3 were grown by solid source chemical vapor deposition on LaA1O3 and post annealed in oxygen at 950°C. Crystals were prepared by LASER heated pedestal growth. The magnetic and electrical transport properties are essentially the same. Below Tc/2 the intrinsic magnetization decreases as T2 (as can be expected for itinerant electron ferromagnets) while the intrinsic resistivity increases proportional to T2. The constant and T2 coefficients of the resistivity are largely independent of magnetic field and alkaline earth element (Ca, Sr or Ba). We identify three distinct types of negative magnetoresistance. The largest effect is observed near the Curie temperature and is likely to be due to magnetic critical scattering. There is also magnetoresistance associated with the net magnetization of polycrystalline samples. The high temperature (above Tc) resistivity of La0.67Ca0.33MnO3 is consistent with small polaron hopping conductivity with a transition at 750K, while La0.67Sr0.33MnO3 does not exhibit activated conductivity until about 500K, well above Tc. The limiting low and high temperature resistivities may place a limit on the maximum possible magnetoresistance of these materials.
Semiconductive Behavior of Sb Doped SnO2 Thin Films
Authors: Grosse-Holz K.-O. , Cillessen J. F. M. , Prins M. W. J. , Blom P. W. M. , Wolf R. M. , Feiner L. F. , Waser R. 
Published: April 2011

AbstractSb doped SnO2 has been deposited on polished ceramic Al2O3 substrates by Pulsed Laser Deposition. Conductivity, charge carrier density and mobility of these thin films have been measured as a function of temperature. A model for the electrical properties of the films is proposed. Since Sb doped SnO2 is a transparent, high mobility material, it is shown that it can be used as channel material for an all-oxide thin film transparent field-effect transistor with a linear dielectric.