bluuebunny/crossref_metadata_2025 huggingface dataset:
Strain Relaxation During Growth Of Epitaxial Fe on Cu(O01)/MgO(001)
Authors: Daniels B. J. , Rensing N. M. , Bain J. A. , Brennan S. , Lairson B. M. , Payne A. P. , Clemens B. M.
Published: March 2011

The strain relaxation of sputter-deposited epitaxial Fe on Cu(001)/MgO(001) was observed in-situ for coverages of I to 200 equivalent monolayers of Fe. Grazing incidence x-ray scattering (GIXS) with synchrotron radiation allowed the precise determination of the in-plane strain in the Fe film. The highest observed elastic strain for the Fe was -10.3% which is in agreement with the lattice parameter mismatch between Fe and Cu for both (001)- and {211}-oriented growth. In-plane rocking curves revealed a bifurcation of the Fe(110) and Fe(220) peaks which is due to the rotation of islands to reduce strain energy. The angle of rotation of these islands was found to depend upon the amount of strain relaxation that had occurred in each island, in agreement with a simple theory for strain relaxation via the creation of a misfit dislocation network. The absence of Fe(200) intensity at small Fe thicknesses, coupled with out-of-plane symmetric and pole figure scans, suggest that Fe islands are tilted out of the plane of the sample about the Fe<110> axes by an angle consistent with Fe{211}-oriented growth. At larger thicknesses Fe(001) growth becomes dominant.
Stacking Fault-Like Fringes Along <010> Directions Observed in In0.52Al0.48 as Layers on the (100) Zone Axis
Authors: Peiró F. , Cornet A. , Morante J. R.
Published: March 2011

In this paper we present the TEM observations carried out on In0.52Al0.48As layers grown on InP at Tg+570°C. Plane view observations along the (100) zone axis show the existence of two types of contrast irregularity, with dark-bright fringes along the <010> directions and extinction for g +040 type reflections. One of these structures has been clearly related to precipitates at the lnAlAs/InP interface. The other, presents stacking fault-like fringes on the (100) plane, and the analysis of its traces on both (100) and (011) planes are presented. Despite the fact that its appearance resembles that of the structure linked to the precipitates, we will show that they are different phenomena and may even coexist.
X-Ray Diffraction Determination of Interface Roughness in GaAs/AlxGa1-xAs Multilayers
Authors: Nayak S. , Redwing J. M. , Kuech T. F. , Phang Y.-H. , Savage D. E. , Lagally M. G.
Published: March 2011

X-ray diffraction has been used to quantify the interface roughness of GaAs/AlxGa1-xAs multilayers. X-ray measurements, both θ-2θ and rocking-curve analyses, quantitatively determine the correlated and random components of the interface roughness as well as the correlation length of the roughness along the interface. The multilayer structures of GaAs/Al0.3Ga0.7As and GaAs/AlAs differ substantially in the amplitude and correlation length of the interface roughness. The change in interfacial roughness is compared to that determined from low temperature photoluminescence (PL) measurements, the conventional measure of interface uniformity.
Effects of Growth Conditions and Substrate Orientation on the Properties of InSb
Authors: Biefeld R. M. , Baucom K. C.
Published: March 2011

Two new organometallic Sb sources, tris(dimethylamino)antimony (TDMASb), and tertiarybutyldimethylantimony (TBDMSb) are being investigated. The growth of InSb using TDMASb, or TBDMSb and TMIn was investigated over a temperature range of 350 to 475 °C using a range of V/III ratios, growth rates and pressures. Misoriented InSb substrates were also used for selected growth conditions The growth rates of lnSb using TMIn and either TDMASb or TBDMSb at temperatures <= 425 °C were proportional to both the TMIn flow rate and the temperature. The surface morphology of InSb grown using either TDMASb or TBDMSb was very rough for growth temperatures <=425 °C. This may be due to the complex decomposition mechanisms involved and the presence of methyl groups on the surface. Smoother backgrounds were generally found when using off axis substrates. The details of the defects observed on the surfaces were dependent on the type of misorientation and can be related to the atomic structure of the surface steps. Both n- and p-type InSb were grown using TBDMSb or TDMASb and TMIn with mobilities up to 68,990 and 7773 cm2/Vs, respectively, at 77 K. The mobility for lnSb using either TDMASb or TBDMSb was optimized by going to lower temperatures, pressures and V/III ratios. The opposite was true for surface morphology which improved with higher temperature, pressure, and V/III ratio. The growth of high mobility InSb with smooth surfaces at T< =425 °C was not achieved with TDMASb or TBDMSb and TMIn under the conditions investigated in this work.
Epitaxial CoSi2 Film Formation on (100) Si by Annealing of Co/Ti/Si Structure in N2
Authors: Ogawa Shinichi , lawrence M. , Dass A. , Fair James A. , Kouzaki Takashi , Fraser David B.
Published: March 2011

CoSi2 was formed by annealing a multilayer strucure of sputter deposited Co / Ti / Si. The Ti was 1, 2 or 5 nm thick and the Co was 15 nm thick. The morphology of both the surface and the CoSi2 / Si interface was examined. For the sample that had 2 nm Ti layer, an epitaxial CoSi2 was formed with both a planar surface and a planar CoSi2 / Si interface. An amorphous Ti-Si-O layer was initially formed between the Co and the Si. Co then diffused through this layer and directly formed epitaxial CoSi2 on the Si<100>. No intermediate silicide phases of Co were observed.
Ordered Structures of Zn1−xFexSe Epilayers Grown on InP and GaAs Substrates
Authors: Park K. , Wei H.- Y. , Salamanca-Riba L. , Jonker B. T.
Published: March 2011

We present evidence for two types of ordered structures, CuAu-I and CuPt, in Zn1−xFexSe (x≈ 0.4) epilayers grown by molecular beam epitaxy. These ordered structures are observed in both electron diffraction patterns and cross-sectional high-resolution lattice images. The CuAu-I ordered structure occurs in Zn1−xFexSe epilayers grown on (001) InP substrates, while the CuPt-type occurs in epilayers grown on (001) GaAs substrates. The ordered structure of Zn1−xFexSe grown on InP substrates consists of alternating ZnSe and FeSe layers along the [001] growth direction and the [110] direction. In contrast, the ordered structure of Zn1−xFexSe grown on GaAs substrates consists of alternating ZnSe and FeSe layers along the < 111 > directions. We have also investigated the role of the misfit strain associated with the lattice mismatch between the epilayers and the substrates on the type of ordered structure.
Nucleation and Growth Model for Metal-On-Fcc(100) Metal Deposition
Authors: Bartelt M. C. , Evans J. W.
Published: March 2011

We present results of Monte Carlo simulations of irreversible diffusion-mediated nucleation and growth of square islands during deposition. This model mimics metal-on-fcc(100) metal epitaxy at lower temperatures. Our analysis focuses on the scaling of the island size and separation distributions, and their evolution with coverage. The depletion in the density of nearby island pairs is shown to produce a “Henzler ring” structure in the diffraction intensity profile.
Low Temperature Si Homoepitaxy: Effects of Impurities on Microstructure
Authors: Adamst D. P. , Eaglesham D. J. , Yalisove S. M.
Published: March 2011

Hydrogen is shown to influence the surface roughness during low temperature Si MBE. Small partial pressures (1 × 10-7 Torr) of deuterium, introduced during Si growth at 310°C, are sufficient to increase the surface width to ∼30 Å before breakdown of epitaxy. This work is consistent with previous studies of the dependence of epitaxial thickness on hydrogen partial pressure and supports a model in which surface roughening leads to the breakdown of epitaxy.
Competing Kinetic and Thermodynamic Processes in the Growth and Ordering of Ga0.5In0.5P
Authors: Kurtz Sarah R. , Olson J. M. , Arent D. J. , Kibbler A. E. , Bertness K. A.
Published: March 2011

The band gap of Ga0.5In0.5P is studied as a function of growth temperature, growth rate, and substrate misorientation. As each of these parameters is independently varied the band gap first decreases, then increases, resulting in “U” shaped curves. Each “U” shaped curve shifts if any other growth parameter is varied. The data presented here can be divided into two regions of parameter space. In the low temperature, low substrate misorientation, high growth rate region, the band gap is shown to decrease with increasing growth temperature, decreasing growth rate, and increasing substrate misorientation. In the high temperature, high substrate misorientation, low growth rate region, the opposite trends are observed. The implications of these data on the ordering mechanism are discussed.
Formation of Intrinsic Defects at MBE-Grown GaAs/AlAs Interfaces
Authors: Krispin P. , Hey R. , Kostial H. , Höricke M.
Published: March 2011

We report on a detailed investigation of MBE-grown isotype silicon-doped heterostructures by capacitance/voltage (C/V) technique and deep-level transient spectroscopy (DLTS). A sequence of electrically active defects is found. By depth profiling of the density of the dominant levels it is demonstrated that the corresponding defects are concentrated at the GaAs-on-AlAs (inverted) interface. By comparison with studies on irradiation-induced levels in LPE- or VPE-grown AlGaAs we conclude that the defects at the GaAs/AlAs interface are most probably linked to different charge states of the arsenic vacancy VAs and VAs−ASi pairs.
Growth Morphology of InN Thin Films by Scanning Tunneling and Atomic Force Microscopies and X-Ray Scattering
Authors: Bryden Wayne A. , Hawley Marilyn E. , Ecelberger Scott A. , Kistenmacher Thomas J.
Published: March 2011

Absiract

The evolution of the growth morphology of thin films of InN on (00.1) sapphire and on (00.1) sapphire prenudeated by a layer of AIN have been followed as a function of the thickness of the InN overlayer. The InN thin films and the AIN nucleation layers were deposited by reactive magnetron sputtering and first characterized by X-ray scattering, profilometry, and electrical transport. These AIN-nucleated InN films displayed heteroepitaxial grains, and high Hall mobility -even in the limit of InN overlayer on the order of 20-40Å. In parallel, InN films of varying thickness were grown directly onto (00.1) sapphire. These films showed a mixture of textured and heteroepitaxial grains, and lower Hall mobility. Atomic force and scanning tunneling microscopy studies have focussed on the morphology of the InN films with thicknesses: (a) much smaller than the AIN nucleation layer; and, (b) near the morphological transition that occurs at ∼1μm and has been attributed to the crossover from a 2D to a 3D growth mechanism. Additional correlations of X-ray structural coherence with growth mode are also examined.
Effects of Hyperthermal Carbon Subimplantation Doping on the Raman Spectra of Gaas
Authors: Fons P. , Makita Yunosuke , Kimura Shinji , Iida Tsutomu , Yamada Akimasa , Shibata Hajime , Obara Akira , Tsai Yushin , Uekusa Shin-Ichiro
Published: March 2011

The structural effects of low-energy (30-500 eV), mass separated C12 Ion doping of GaAs simultaneous with conventional solid source MBE growth have been studied using room-temperature raman scattering, Hall-effect, transmission electron microscopy and 2K photoluminesence measurements for GaAs epitaxy temperatures of 550 ºC. Results indicate good acceptor activation without detectable residual damage is achieved for ion energies ≤ 240 eV, while at EIon = 500 eV, residual damage is present with a corresponding reduction in electrical activation. Low-energy TRIM calculations indicate that the damage is related to the increased depth distribution of vacancies and interstitials created during the higher (500 eV) implantation process which can not be annealed out at growth temperatures. Constant energy (100 eV) film growth experiments for a range of implantation currents (45 pA/cm2 - 45 nA/cm2) and growth temperatures of 550 and 550 ºC, show LO Raman peak broadening and mode hardening for currents ≥15 nA while maintaining very high C acceptor activation. This is interpreted as residual stress due to small amounts of interstitial C in the highest doped films. Both Hall mobility measurements and photoluminesence show no evidence of C dopant compensation.
Light Impurity Depth Profiling in the Nuclear Reaction AnalysiS
Authors: Zabashta Oleg I. , Kul'ment'ev A.I. , Storizko V.E.
Published: March 2011

The general problem in the analysis of a sample by non-destructive techniques such as nuclear microanalysis, ellipsometry, etc. is the interpretation of the measured data. The impurity depth profile obtained may noticeable non-physical fluctuations. From the mathematical point of view this could be explain by the fact that while interpreting the results we have to solve an incorrect problem to which routine computational methods are not applicable.
Extended Damage Depth Determinations in AR- and H-Implanted Silica Glass
Authors: Arnold G.W. , Battaglin G. , Mazzoldi P.
Published: March 2011

Damage depths for Ar-implanted fused silica have been examined by Rutherford backscattering (RBS) and elastic recoil detection (ERD) ion-beam analysis. H incursion (6 at. %) from ambient atmospheres to twice TRIM values was found for damage depths which intersected the surface. H implants were used to decorate Ar damage for deeper Ar implants. The incursion of H for high-fluence implants is important for optoelectronic applications.
Dynamic Annealing and Amorphous Phase Formation in Si, GaAs and AlGaAs Under Ion Irradiation
Authors: Williams J.S. , Tan H.H. , Goldberg R.D. , Brown R.A. , Jagadish C.
Published: March 2011

Ion damage processes and amorphous phase formation are compared in Si, GaAs and Alx Ga1-x As materials in the critical regime where dynamic defect annealing is strongly competing with ion damage production. It is shown that the nature of residual damage is very strongly dependent on temperature, ion dose and dose rate in this critical regime for both Si and GaAs and that the amorphous phase can be “nucleated” by high levels of extended defects. In Alx Ga1-x As, the amorphous phase is increasingly more difficult to nucleate with increasing Al concentration at LN2 temperature but can be nucleated at sufficiently high implantation doses for all Al concentrations. No dose rate effect is observed for Alx Ga1-x As. This behaviour is discussed in terms of the availability of mobile defects and bonding configurational changes during irradiation.
RBS Study of the Diffusion of Implanted Au and Pb in α-Zr
Authors: R.S. Cesar , Silva Da , Zawislak Fernando C.
Published: March 2011

The diffusion and solubility of Au and Pb in α-Zr are measured in the temperature ranges of 773-973 K and 773-1023 K, respectively, using the Rutherford backscattering technique. Au and Pb have been implanted in samples of Zr having different amounts of Fe as impurity. The results indicate that both solutes follow a substitutional extrinsic diffusion process enhanced by the fast diffusing Fe impurity, and that the solid solubility of Au and Pb in Zr is of ≈lat% in the measured range of temperature.
Diffusion of Ion Implanted Ruthenium and Osmium IN GaAs and InP
Authors: Kuttler M. , Knecht A. , Bimberg D. , Kräutle H.
Published: March 2011

The redistribution of the dopants Ru and Os implanted into GaAs and InP as well as the structural properties of the hosts are investigated in dependence of the annealing procedure. Results of Rutherford backscattering and secondary-ion-mass-spectroscopy experiments are presented. The RBS results of Os in GaAs annealed at 850°C indicate that an amount of about 1018 cm-3 Os is on substitutional sites. Two different diffusion processes are observed: an uphill diffusion in the amorphized region and a Fick-type diffusion in the tail of the depth profiles. The diffusion coefficients for Ru in GaAs at 850°C and Os in InP at 750°C are estimated to 4*10-14 cm2s-1 and 8*10-15 cm2s-1, respectively.
Modeling of Dopant Diffusion during Annealing of Sub-Amorphizing Implants
Authors: Dunham Scott
Published: March 2011

Ion implant annealing is a complicated process involving the interactions of point defects generated during the implantation, implanted or previously present dopants, and extended defects which form as a result of the implant damage. To effectively model the process, it is essential to determine the critical processes, assess the validity of assumptions and calculate appropriate parameter values. In addition, implant annealing is just one element in the VLSI fabrication process, and the model development must consider the process as part of the broad range of experimental observations, as it is only through consistent physical models that simulators can predict the multiple interactions and two and three-dimensional effects present in VLSI structures. This work focuses on enhanced diffusion following silicon implants below the amorphization threshold as a function of dose, energy and time.
Induced Crystallization in CW Laser-Irradiated Sol-Gel Deposited Titania Films
Authors: Exarhos Gregory J. , Hess Nancy J.
Published: March 2011

Isothermal annealing of amorphous TiO2 films deposited from acidic sol-gel precursor solutions results in film densification and concomitant increase in refractive index. Subsequent heating above 300°C leads to irreversible transformation to an anatase crystalline phase. Similar phenomena occur when such amorphous films are subjected to focused cw laser irradiation. Controlled variations in laser fluence are used to density or crystallize selected regions of the film. Low fluence conditioning leads to the evolution of a subtle nanograin-size morphology, evident in AFM images, which appears to retard subsequent film crystallization when such regions are subjected to higher laser fluence. Time-resolved Raman spectroscopy has been used to characterize irradiated regions in order to follow the crystallization kinetics, assess phase homogeneity, and evaluate accompanying changes in residual film stress.
Atomic Transport by Ballistic Atomic Mixing Effect in Bilayer Structure
Authors: Chae K.H. , Choi J.M. , Jung S.M. , Song J.H. , Woo J.J. , Whang C.N.
Published: March 2011

A dynamic Monte-Carlo simulation (MCS) program, containing not only collisional mixing but also sputtering effects, has been used to elucidate the dynamic mixing processes and the atomic transport of constituents in Al-Pd bilayer systems. MCS results reveal that the preferential inward displacement of the top layer element dominates, and that there is an enhancement of the inward displacement when the heavier element is in the top layer. The inward displacement is controlled by both of an anisotropic and isotropic atomic transport. The anisotropic term is caused by the primary recoil of atoms, which has a characteristic of φ(ion dose) dependence, and the isotropic term is associated with the random cascade motion, which has a dependence. However the outward displacement is governed by only the isotropic motion, thus the inward displacement always dominates over the outward motion, which leads to a preferential displacement of top layer element to the bottom layer.
The Effects of Amorphous Layer Regrowth on Carbon Activation in GaAs and InP
Authors: Moll A.J. , Ager J.W. , Yu K.M. , Walukiewicz W. , Haller E.E.
Published: March 2011

The effect of the Ga dose on the activation of implanted carbon in GaAs is determined. The free hole concentration is found to depend on the depth of the amorphous layer created by the Ga co-implant. Initial results on C implantation in InP indicate the behavior of C is very different in InP when compared to GaAs. The role of precipitation in reducing the activation of C in both GaAs and InP is discussed.
Binding of Copper and Nickel to Cavities in Silicon Formed by Helium Ion Implantation
Authors: Myers S.M. , Follstaedt D.M. , Bishop D.M.
Published: March 2011

Cavities formed in Si by He ion implantation and annealing are shown be strong traps for Cu and Ni impurities. Experiments utilizing ion-beam analysis and transmission electron microscopy indicate that Cu is trapped at the internal surfaces of cavities up to ≈1 monolayer coverage with a binding energy of 2.2±0.2 eV relative to solution. This is greater than the heat of solution from the precipitated Cu3Si phase, determined to be 1.7 eV in agreement with earlier work. Copper at cavity-wall sites is reversibly replaced by H during heating in H2 gas, indicating the relative stability of the two surface terminations. Initial results for Ni impurities indicate that trapping at cavities is again energetically preferred to suicide formation. The saturation coverage of Ni on the internal surfaces, however, is an order of magnitude smaller for Ni than Cu, consistent with published studies of external-surface adsorption. These results suggest that cavity trapping may getter metallic impurities in Si more effectively than methods based on suicide precipitation.
Channeling Phenomena of Direct Si-Implantation to Liquid-Glass Encapsulation Czochralski GaAs Crystal Wafers Through Observation of Threshold Voltages
Authors: Saito Yasuyuki , Fukuda Katsuyoshi
Published: March 2011

Threshold voltages of Si-implanted gallium arsenide (GaAs) MESFETs depend on not only wafer crystallographic characteristics, but also MESFET fabrication processes. When the position of the orientation flat was changed to improve mechanical shock tolerance, it was found that Vth varied on the wafers due to a crystallographic orientation effect on the Si implantation. Thus, we investigated Vth distributions on wafers of several different Si implantation orientations. It was confirmed that Vth largely varies according to Si-implantation orientations.
Structure and Electrical Properties of Yttria Stabilized Zirconia by Iron Ion Implantation
Authors: Guomei Wang , Zuyuan Qu
Published: March 2011

Fe ions were implanted into yttria stabilized zirconia with doses of 5×1015 -2×1017 ions/cm2 at an energy of 140 KeV. The effects of Fe-implanted zirconia and post-implantation thermal annealing on electrical properties and structure of an implanted layer were studies by electric measurement, X-ray photoelectron spectroscopy (XPS) and X-ray diffraction (XRD). It was found that the resistivity for the as-implanted sample decreased greatly with increasing ion dose, and at high dose the resistivity decreasing gradually. After annealing at 1200°C in N2 environment, the resistivity relative to that for the as-implanted sample had clearly marked decreases. Results of the XRD and XPS measurements showed that the implanted Fe ion was mainly in a charge state of Fe2+ and the sections of Fe2+ were incorporated into the ZrO2 lattice, forming a FeZrO3 compound. Finally, the conductivity mechanisms were discussed briefly.
Effects of annealing and cobalt implantation on the optical properties of βFeSi2.
Authors: Finney M S , Yang Z , Harry M A , Reeson K J , Homewood K P , Gwilliam R M , Sealy B J
Published: March 2011

In this paper optical absorption and photoluminescence (PL) techniques are used to study the optical properties of βFeSi2 layers fabricated by Ion Beam Synthesis (IBS). The way in which the band-gap varies when a small dose of Co is added before Fe implantation is also investigated. Our results indicate that the band-gap for βFeSi2 is direct with a value of O.87eV. When a sufficiently high dose (1×1016cm-2) of Co is implanted prior to Fe we see the appearance of an additional band-gap after annealing at 1173K which we attribute to the formation of a ternary CoxFeySiz, phase. We also show that by placing the sample in a hydrogen plasma it is possible to raise the temperature at which PL occurs in βFeSi2 to ~ 200K.
Temperature Dependence of the Fading Speed of Blue-Green Produced by Cu Ion Implantation into LiNbO3
Authors: Saito Yukinori , Suganomata Shinji , Moretti P.
Published: March 2011

The optical properties of colorless and transparent crystals can be changed by introducing impurities into the crystal and depend on the elements added. What kind of elements should be added depends on how one modifies the properties. If one wants to put beautiful color on some colorless and transparent crystals such as Al203, SiO2, LiNbO3, etc., it is necessary to produce definite absorption peaks in the visible region for the crystals. In case of using ion implantation for introducing impurities, there is essentially no limitation to the combination of host crystal and impurities.
Thermal Surface Treatment Using Intense, Pulsed Ion Beams
Authors: Stinnett R. W. , Buchheit R. G. , Greulich F. A. , Hills C. R. , Kilgo A. C. , Mclntyre D. C. , Greenly J. B. , Thompson M. O. , Johnston G. P. , Rej D. J.
Published: March 2011

Surface treatment experiments using intense pulsed ion beams have demonstrated new capabilities for materials surface treatment. These experiments have confirmed corrosion resistance, surface hardening, amorphous layer and nanocrystalline grain size formation, metal surface polishing, controlled melt of ceramic surfaces, surface cleaning and oxide layer removal by rapid melting and resolidification. Deposition of beam energy in a thin surface layer allows melting of the layer with relatively small energies (1-10 J/cm2) and allows rapid cooling (109-1010 K/sec) and resolidification of the melted layer by thermal diffusion into the underlying substrate. At higher intensities (≥20 J/cm2), this technology can provide rapid ablation of material from targets followed by rapid, congruent deposition of polycrystalline thin films on substrates. This technology uses high energy pulsed (40–400 ns) ion beams to directly deposit energy in the top 2–20 micrometers of the surface of materials.
U.S. DoD Applications of Ion Beam Processing
Authors: Hirvonen James K.
Published: March 2011

Selected usages of ion beam processes within the U.S. Department of Defense (DoD) are discussed in terms of their technical merits, their current status, and the various factors governing their acceptance within the DoD user community.
Ion Beam Assisted Deposition- R&D to Production
Authors: Hirvonen James K.
Published: March 2011

Ion Beam Assisted Deposition (IBAD) involves vacuum deposition processes which incorporate concurrent energetic ion bombardment and material deposition. The effects of the ions are to promote adhesion, densify the films, and to help chemically incorporate reactive ions into the coatings. Examples of IBAD studies that have progressed from R&D to production status are presented with a discussion of the technical and marketing factors influencing their commercial acceptance.
Tantalum Ion Implantation into Cu-12Nb for Electromagnetic Railgun Technology
Authors: Otooni M.A. , Brown Ian , You Xiang , Foner S.
Published: March 2011

Analysis of fired rails from electromagnetic railgun indicates gross surface melting near the breach end of the rails. This effect is most likely caused by joule heating and arc erosion. To improve the mechanical behavior of the rail material, alloys of copper, such as Cu-0.6 Nb, has been used in the past with moderate success. More recently another alloy of copper, Cu-18 Nb, has become available. Preliminary metallurgical research in the thermomechanical properties of this latter alloy indicates it could be a candidate for application in EM gun systems. In this effort we have attempted to study the influence of ion implantation on the thermomechanical properties of Cu-12Nb alloy. In a series of experiments, Ta ions have been implanted at an energy range of 100–180 KeV and a dose of 5 × 1016 cm-2. Several analytical techniques such as Rutherford Back Scattering (RBS), Scanning Electron Microscopy (SEM), Transmission Electron Microscopy (TEM), arc erosion, and microhardness measurements have been done. It has been shown that although there is an improvement in the microhardness of the implanted materials, the ion implantation saturation dose cannot exceed 5 × 1016 cm-2. Furthermore, the RBS data indicate that the implanted Ta resides mostly at a depth of about 200–300 Å from the surface. Results from the SEM analysis of unimplanted Cu-12Nb indicate the Nb has an acicular morphology and is randomly distributed. Results from microhardness measurements of the implanted materials indicate that implantation enhances the microhardness. In another experiment, such as implantation of Ta in an already TiN coated surface, we observed a similar increase in the microhardness value. We speculate that the microhardness improvement of Cu-18Nb or the Ta implanted TiN surface is due to induce compressional stresses near the lenticular (filament) Nb fibers in the Cu-18Nb composite.
New Method for the Full Processing of Experimental Spectra in the Resonant Nuclear Reaction Analysis
Authors: Kul'ment'ev Alexander I. , Zabashta O.I. , Storizko V.E.
Published: March 2011

Extensive studies of the mathematical and physical aspects of the interpretation of NRA spectra began in the mid - 1980s. A large amount of work [1-3] in this field was done by G.Amsel's group. Various physical effects accompanying the beam - target interaction were analysed and their influence on the accuracy of the concentration profile was evaluated. To solve the direct problem, a program which is now widely used was written on the basis of that study.
The Use of Negative Ions in Ion Implantation with Tandem High Energy Accelerators
Authors: O'Connor John P. , Tokoro Nobuhiro
Published: March 2011

Since the introduction of the G1500 ion implanter, the use of tandem accelerators in production ion implantation systems has become well established. However, the beam currents which are attainable at present at low energies (< 200 keV) are suitable for only low and low-end medium dose implants. An approach to increase low energy beam currents in d.c. tandem accelerators is presented. Specifically, the use of negative ions which have been generated in the injector are transported to the end station and implanted into the wafers. In this work, beam current measurements performed using the G1500 system are presented for the typical semiconductor dopants. System changes which are necessary to accomplish implants with negative ions are discussed. A comparison of sheet resistances and uniformities measured with both positive and negative ions at the same energy and from the same G1500 system are presented. SIMS profile measurements of implants with both positive and negative ions at the same energy are also presented.
Ion Beam Synthesis of Buried COXNi1-xSi2 Layers in Silicon
Authors: Wu M.F. , De Wachter J. , Van Bavel A.-M. , Pattyn H. , Langouche G. , Vanhellemont J. , Bender H. , Temst K. , Wuyts B. , Bruynseraede Y.
Published: March 2011

Heteroepitaxial CoxNi1-xSi2 layers with good crystalline quality have been formed by ion beam synthesis. Rutherford Backscattering (RBS) - Channeling, Auger Electron Spectroscopy (AES), Transmission Electron Microscopy (TEM) and X-Ray Diffraction (XRD) have been used to study the buried layers. For a sample with x=0.66, we found that this ternary suicide layer contains 11% type B and 89 % type A orientation. The TEM investigation reveals that the type B component is mainly located at the interfaces with a thickness of a few monolayers. XRD studies show that the strain of the type B component is smaller than that of the type A component, and this is probably the reason for such a unique distribution of the type B component in the epilayer.
Electrical and Optical PROPERTIES OF Co ALLOYED ß-FeSi2 Formed by Ion Beam Synthesis
Authors: Panknin D. , Henrion W. , Wieser E. , Voelskow M. , Skorupa W. , Vöhse H.
Published: March 2011

By subsequent implantation of iron and cobalt into silicon buried layers of semiconducting ß-(Fe1-xCo1-x)Si2 are formed. The band gap energy as well as the spreading resistance decrease with increasing cobalt content. The microstructure of the suicide layers is characterized by XTEM images.
Formation of CoSi2 Wires by Maskless Implantation with the Focused Ion Beam
Authors: Teichert J. , Bischoff L. , Hesse E , Panknin D. , Skorupa W.
Published: March 2011

The maskless ion implantation with the focused ion beam as a new method for ion beam synthesis of cobalt suicide wires is presented. In order to perform the implantation a special achromatic mass separator was implemented into the ion column, liquid alloy ion sources for cobalt ions were developed and a substrate heating was built. Ion implantation was performed with 30 keV Co+ and 60 keV Co++ ions. The dose dependence for room temperature implantation and the influence of the substrate temperature were investigated.
The Electronic Micro Structure in the Implant Layer of Ion Implanted Polymers
Authors: Giedd R.E. , Robey D. , Wang Y.Q. , Moss M. G. , Kaufmann J.
Published: March 2011

The mechanical and electronic properties of ion implanted polymers have been determined to be a function of ion dose, energy and beam current. In previous studies the implant layer was assumed to be isotropic. In an earlier report we speculated that the implant layer was not isotropic, based on a temperature coefficient of resistivity (TCR) that could not be explained by a single structural configuration[1]. In this study we examined the effect of etching the surface layer, decreasing polymer thickness, on the TCR to determine which part of the implant layer contributed to the various mechanisms of conduction. We have concluded that there are at least two mechanisms responsible for conduction, Mott three dimensional variable range hopping(VRH), and Mott one dimensional VRH. It is possible that other theories may be more correct (e.g. crossover to ES-VRH at low temperatures) since many theories predict the same temperature dependence. We found that conduction with the Mott one dimensional VRH exists at the bottom of the implant layer.
Formation of SiGe and SiGeC Layers on Si by Ge and C Ion Implantation and Subsequent Ion-Beam-Induced Epitaxial Crystallization
Authors: Kobayashi Naoto , Hasegawa Masataka , Phillips J.R. , Hayashi Nobuyuki , Tanoue Hisao , Shibata Hajime , Makita Yunosuke
Published: March 2011

Fabrication of Si1-xGex and Si-1-x-yGexCy layers on Si(100) by high-dose ion implantation of 72Ge ions without and with 12C ions and subsequent high-energy and low-energy ion-beam-induced epitaxial crystallization (IBIEC) has been investigated. Structural properties of the surface layers were observed by RBS-channeling technique. Si(100) wafers were implanted with 150keV and 80keV Ge ions at room temperature so as to produce a peak concentration of Ge amounting to approximately 2 and 14 at.%, respectively. C ions were additionally implanted to a fluence of 10% of Ge concentration for the SiGeC samples. IBΓEC experiments performed with 400keV 18Ar ion bombardments have induced crystallization of the amorphous layers of SiGe and SiGeC on Si up to the surface at 400°C for both samples with low Ge concentration (2%) and high Ge concentration (14%). IBIEC using 72Ge ions with energies whose projected ranges are within the amorphous layer was alternatively performed for SiGe layer on Si. Bombardments of 140keV and 40keV Ge ions at 400°C have induced crystallization up to the surface with a slight disorder in the grown layer. Present experimental results suggest a novel ion beam synthesis method of fabrication of SiGe (SiGeC) on Si at low temperatures.
Ion Implantation of Ti,Mo W,Mo+C and W+C in H13 Steel and Aluminum at Elevated Temperature
Authors: Tonghe Zhang , Fuzhong Wei , Jun Chen , huixing Zhang , Xioji Zhang , Ting Lu
Published: March 2011

The chemical change in the surface of H13 steel or aluminum is produced by implanting a reactive elements, such as Ti, Mo and W. The X-ray diffraction pattern shows that implanted Ti at 400 C has reacted with carbon(0.35 in wt.%) forming a second phase TiC. Auger analysis shows that the carbon atoms have been condensed in the Ti implanted region. Carbon peak concentration of 30 At.% is greater than Ti atom peak concentration of 12 At.%.

Several second phases are formed during pulsed Mo ion implantation 2 into aluminum with high ion flux of 50˜80µA/cm2 which raises the target temperature from 400°C to 600°C.

More second phases are formed by dual Mo+C implantation with high dose of 3˜5×10 17/cm2 and high flux of 50˜75µA/cm2 . And the target temperature is raised from 400 to 600°C. The FeMo Fe3Mo2, Fe2MoC, Mo2C, MoC, MoCx, phases and iron carbides are identified by X-ray diffraction technique.
Oxide Formation on NbAl3, and TiAl Due to Ion Implantation of 18O
Authors: Hanrahan Robert J. , Verink Ellis D. , Withrow Stephen P. , Ristolainen Eero O.
Published: March 2011

Surface modification by ion implantation of 18O ions was investigated as a technique for altering the high-temperature oxidation of aluminide intermetallic compounds and related alloys. Specimens of NbAl3 and TiAl were implanted to a dose of 1×1018 ions/cm2 at 168 keV. Doses and accelerating energies were calculated to obtain near-stoichiometric concentrations of oxygen. Use of 18O allowed the implanted oxygen profiles to be measured using secondary ion mass spectroscopy (SIMS). The near surface oxides formed were studied using x-ray photoelectron spectroscopy (XPS) and Auger electron spectroscopy. Specimens were also examined using x-ray diffraction and SEM. This paper presents results for specimens examined in the as-implanted state. The oxide formed due to implantation is a layer containing a mixture of Nb or Ti and amorphous Al oxides.
Evolution of Defect and Impurity Profile During High Dose Co Implantation into Si at Elevated Temperatures
Authors: Schippel S. , Witzmann A.
Published: March 2011

ȥ111Ɂ -Si was implanted with 250 keV Co ions at a target temperature of 350°C. The ion dose was varied between 1×1014 cm-2 and 2×1017 cm-2 . The evolution of the defect and impurity profile was investigated by Rutherford Backscattering Spectrometry (RBS), channeling and transmission electron microscopy (TEM).

Up to a dose of 1 × 1015 Co cm-2 no defects can be detected. At higher Co doses, we find correlated defects in the center of the Co distribution and point defects in the region below. Moreover, damage accumulation at the surface is observed. The concentration of defects increases with increasing ion dose and reaches its level of saturation at a dose of 2 × 1016 cm-2.

The Co profiles of samples implanted at 350°C differ considerably from the Gaussian shape. The near surface and the back flank are parts of Gaussian distributions. However, the standard deviation of the near surface flank is always smaller than that of the back flank. Moreover, the distributions show tails into the substrate at depths > 320 nm. This proves that radiation damage acts as an effective center for the nucleation of CoSi2.

During annealing we find a redistribution of Co towards the defective regions for Co doses between 1 × 1016 cm-2 and 5× 1016 cm-2.
Metal Vapour Vacuum Arc Ion Source to Synthesize Refractory Metal Silicides
Authors: Liu B.X. , Zhu D.H. , Lu H.B. , Tao K.
Published: March 2011

Metal Vapour Vacuum Arc (MEWA) Ion Source was employed, for the first time, to synthesize metal suicides. Refractory metal suicides NbSi2, TaSi2, WSi2 and MoSi2 were successfully formed by implanting respective metal ions into Si(111) wafers. It was found that the high current density metal ion implantation not only provided the metal components but also caused a simultaneous annealing for various metal-suicide phases to grow. When the impLantation was conducted at 40 kV, the Nb ion current density was up to 76 µA/cm2 at a dose of 4x1017/cm 2, and the Ta, W and Mo ion current densities were up to 65 µA/cm2 at a dose of 5×1017 ions/cm2 , hexagonal NbSi2, TaSi2, MoSi2 and WSi2 were formed. Post annealing transformed the WSi2 and MoSi2 phases from hexagonal to tetragonal structure, featuring lower resistance than that of the as-implanted ones.
Characterization of Ion Beam Synthesized Materials Using Microscope-Spectrophotometry
Authors: Geatches Rachel M. , Reeson Karen J. , Criddle Alan J. , Finney Mark S. , Harry Milton A. , Webb Roger P. , Pearson Peter J.
Published: March 2011

In this paper, the technique of microscope-spectrophotometry, used to nondestructively characterize the microstructure of ion beam synthesized iron-disilicide layers, is described. The results obtained agree extremely well, in terms of layer thickness and interfacial roughness, with those from Rutherford backscattering. The results also show that it is possible to interpret the measured spectral reflectance data in terms of: 1) defect annealing; 2) iron redistribution; and 3) phase transformations from the β to the α phase.
Is Self-Organisation During Ostwald Ripening a Crucial Process in Ion Beam Synthesis ?
Authors: Reiss S. , Heinig K.-H. , Weber R. , Skorupa W.
Published: March 2011

Results of a computer simulation of Ostwald ripening during ion beam synthesis of a SIMOX layer are presented. Based on investigations of the as-implanted state the simulation starts with equal-sized SiO2 precipitates, homogeneously distributed in a layer. The simulation shows clearly that Ostwald ripening forms structures in such a system by means of self-organisation.

This structure forming process explains in a simple and consistent manner structures of in the concentration profile like ”humps”, ”spikes” and ”banding”, which have been observed experimentally.
Synthesis of Si1-xGex-on-Insulator by 74Ge+ Ion Implantation in a Simox Substrate
Authors: Patel C.J. , Marsh C.D. , Magnusson U. , Jeynes C. , Ostling M. , NorströM H , Booker G.R. , Butcher J.B.
Published: March 2011

A single crystalline Si1-xGex overlayer on insulator is realised by the implantation of germanium into a SIMOX (Separation by IMplantation of OXygen) substrate. Two SIMOX samples were implanted with 74Ge+ at elevated temperature (≈600°C), and subsequently annealed at different temperatures and anneal ambients. The microstructure, stoichiometry, and conductivity of the Si1-xGex over-layer were studied using transmission electron microscopy, Rutherford backscattering spectrometry/ion channelling and two-probe conductivity measurements. As a result of lattice reordering after final heat treatment, and despite high defect density observed in the XTEM microstructure, the measured conductivity of the over-layer is higher than of the starting SIMOX material. These results suggest a possibility of band-gap engineering by synthesis of Si1-xGex-on-insulator.
In-Plane Magnetic and Structural Anisotropies in NI and FE Films Produced by Ion-Assisted Deposition
Authors: Lewis W. A. , Farle M. , Clemens B. M. , White R. L.
Published: March 2011

We report the results of our microstructural investigations into the origin of in-plane uniaxial magnetic anisotropies induced in Ni and Fe thin films by low energy ion beam assisted deposition. 1000 Å films were prepared by ion beam sputtering onto amorphous silica substrates under simultaneous bombardment by 100 eV Xe+ ions under an oblique angle of incidence. The induced anisotropy is studied as a function of ion-to-adsorbate atom arrival ratio, R, from values of 0 to 0.35. The maximum anisotropy field is 150 Oe for Ni and 80 Oe for Fe, but their hard axes are oriented orthogonal to each other. Asymmetric x-ray diffraction is employed to study both in-plane and out-of-plane lattice spacings and crystallographic orientation. In agreement with previous work, we find evidence of a anisotropic in-plane strain of magnitude 0.2-0.5%. In all films, the direction perpendicular to the ion bombardment is compressed relative to parallel. The uniaxial magnetic anisotropy is correlated with this in-plane anisotropic strain using a simple magnetoelastic model.
Surface Microstructure of High Temperature Beryllium Implanted with Deuterium
Authors: Touhouche K. , Terreault B.
Published: March 2011

We have investigated implantation temperature effects on the formation of blisters on the surface of Be foils implanted with low energy, 1.5 keV, deuterium ions to doses ranging from 3×1016 to 1.2×1018 ions cm-2, a dose exceeding by far the saturation (≈1.8×1017 ions cm-2: 30% at.). The implantation temperature was varied from 293 K (RT) to 983 K. The samples have been characterized by scanning electron microscopy (SEM). For saturated samples, blisters were present even at high temperatures, viz 983 K, and no blisters were found for samples implanted below 20% at.. However, on samples in which a dramatic grain growth has been observed, blisters were found to decorate the grain boundaries and to interconnect with each other. The average blister diameter increases with increasing temperature, thus indicating the thermodynamical aspect of blister formation and coalescence. On the other hand, for low temperature (473 K), the surface structure that has developed is similar to that at RT, except for an increased most probable blister diameter and blister density, and there was no indication that the blisters ruptured. The blister skin thickness agrees well with the projected range of the implanted ions. Over-saturated samples at RT retained only ≈30% at., corroborating the observations that some blisters formed on already ruptured ones.
Oxidation of Si via Solid State Interfacial Reaction with Deposited Sn-Doped In2O3
Authors: OW Yang Cleva W. , Shigesato Yuzo , Paine David C.
Published: March 2011

We have developed a novel solid-state method for forming interfacial silicon dioxide by a two step process of rf sputtering tin-doped indium oxide (ITO), a transparent conductor, onto Si substrates followed by annealing at 800°C in flowing ultra-high purity nitrogen. TEM, XRD, FTIR, and C-V measurements were used to characterize the microstructure and morphology of as-deposited and annealed samples. The silicon dioxide layer grows interfacially between Si and In2O3 and, for a 5 nm thick oxide, is planar on a 2–4 monolayer scale over hundreds of nm. The kinetics of the solid-state interfacial oxidation reaction were studied and a model has been developed.
Hot Electron Phenomena in Transport Across Metal-Semiconductor Structures
Authors: Ludeke R. , Bauer A.
Published: March 2011

Ballistic Electron Emission Microscopy (BEEM) is shown to be a versatile spectroscopic tool to investigate scattering phenomena of energetic electrons. Two examples are given for obtaining numerical values of scattering parameters. Thus the elastic and inelastic mean free paths are deduced from model fits to attenuation data for thin Pd films deposited on Si(111) and Si(100) substrates. In the second example, the quantum yield for electron-hole pair production through impact ionization of hot carriers injected into Si(111) is directly measured over an energy range from 1-7 eV.
Formation of Chemically Clean and Morphologically Smooth PtSi/Si Interfaces
Authors: Das Suhit R. , Xu D-X. , Phillips J. , McCaffrey J. , LeBrun L. , Naem A.
Published: March 2011

PtSi/Si interfaces have been formed by depositing Pt layers on chemically cleaned, lightly doped, n-type Si (100) wafers in a UHV magnetron sputter-deposition system using ultra high purity Ar as the sputter gas, followed by ex-situ silicidation in N2ambient utilizing a 3-step rapid thermal annealing (RTA) process. The polycrystalline PtSi layer, with oriented grains ranging in size from 50-100 nm, exhibits a columnar growth morphology. The PtSi/Si interface is planar with interface roughness in the order of 5 nm peak-to-peak. Auger depth profile shows uniform composition through the PtSi layer and a clean and chemically abrupt PtSi/Si interface.