bluuebunny/crossref_metadata_2025_split huggingface dataset:
Structural Characterization of Pt/Co Multilayers for Magnetooptic Recording Using X-Ray Diffraction
Authors: Bain James A. , Clemens Bruce M. , Brennan Sean 
Published: September 2012

ABSTRACTStructural features in magnetic multilayer films such as interfacial sharpness and in-plane stress are regarded as responsible for the perpendicular magnetic anisotropy observed in these films. The Multilayers often consist of alternating magnetic and non-Magnetic layers, and the degree of interfacial sharpness between the two is a critical component in producing perpendicular anisotropy. Additionally, in-plane stress affects the anisotropy through Magnetostriction. In this work, we measure both the composition modulation and the stress in multilayers of Pt/CO with x-ray diffraction. Quantitative information about the composition modulation is extracted by recursively fitting a model of multilayer diffraction to the high angle superlattice lines. The Model incorporates a composition modulation of variable amplitude, along with a statistical description of the layer thickness fluctuations.
Magnetic and Magneto-Optic Properties of PtFe (001) and PtCo (001) Thin Films
Authors: Lairson Bruce M. , Visokay Mark R. , Sinclair Robert , Clemens Bruce M. 
Published: September 2012

ABSTRACTWe report on the magnetic and Magneto-optical properties of PtFe and PtCo intermetallic thin films when they have the CuAu(I) tetragonal structure and their crystallographic C axis is oriented out of the film plane. These films possess large perpendicular magnetic anisotropy energies. We observe changes in the Magneto-optic Kerr rotations of Pt-Fe and Pt-Co alloys associated with the formation of the uniaxial CuAu(I) crystal structure. In particular, we report the observation of up to 60% enhancement in the Magneto-optic Ken-rotation for ordered, epitaxial PtFe intermetallic alloy over that of the random face centered cubic alloy. This enhancement is wavelength dependent, with a peak in the visible light range at 2.0 eV.
Magnetic Properties and Crystallography of Selected Co/Pt Multilayers with Rare-Earth Additions
Authors: Bertero G.A. , White R.L. , Sinclair R. 
Published: September 2012

ABSTRACTWe have sputter-deposited a series of Pt/CO Multilayers with differing amounts of rare-earth (RE) in an effort to improve the uniaxial perpendicular anisotropy in these structures. The present work investigates the influence on the magnetic properties of Tb and Ho incorporated both at the interfaces of Pt/CO Multilayers and into the Co layers. The uniaxial anisotropy improved significantly only for those multilayers that showed poor perpendicular anisotropy in the undoped state, in particular, those with large (∼30 Å) bilayer periods. High resolution transmission electron microscopy was used to study these multilayers in cross-section. The Multilayer structures present strong [111] texture with grain sizes ranging from 200 to 600 Å. It is found that the RE does not produce a significant change in the growth texture of the multilayers until a critical amount is introduced beyond which the multilayer structure amorphizes resulting in a compositionally modulated amorphous film.
The Microstructure and Giant Magnetoresistance of NiFeAg Thin Films
Authors: Parker Michael A. , Coffey K. R. , Hylton T. L. , Howard J. K. 
Published: September 2012

ABSTRACTAlthough Much has been published on giant Magnetoresistance (GMR) in co-deposited thin films [1–4], only little [5] has been published on the structure-property relationships limiting the effect. Here, we report the results of microstructural characterization of NiFeAg thin films that exhibit a GMR effect. The as-deposited films show a sizeable GMR effect. The Maximum GMR effect observed was 6.4% with -4k0e FWHM of the 6P/P peak. Upon annealing these films, the GMR at first increases, and then decreases. We present microstructural evidence from TEM and XRD, amongst other techniques, which shows that this is a consequence of the initial NiFeAg thin film agglomerating into NiFe grains in a predominantly Ag segregant Matrix. Upon extended annealing, excessive grain growth leads to a decrease in the GMR as predicted by the model of Berkowitz, et al. [1].
Structural Analysis of Pulsed Laser Deposited FeSi2 Films
Authors: Karpenko O.P. , Olk C.H. , Doll G.L. , Mansfield J.F. , Yalisove S.M. 
Published: September 2012

ABSTRACTThis study focuses on the characterization of iron silicide grown, for the first time, by pulsed laser deposition on Si(111). Silicide growth was attempted both by deposition of pure Fe followed by annealing, and congruent deposition of Fe and Si from a stoichiometric FeSi2 target. The films formed by deposition of pure Fe and annealing did not grow epitaxially on Si(111) and contained a number of phases including β-FeSi2. Films grown by congruent deposition of Fe and Si did grow epitaxially on Si(111) and contained either pure β-FeSi2 or a mixture of both FeSi and β-FeSi2, depending on deposition conditions. The following epitaxial orientations were observed: β-FeSi2(001)//Si(111), β-FeSi2[010]//Si<110> with three variants, and FeSi(111)//Si(111), FeSi[110]//Sit[112^. Films of various thicknesses were analyzed with conventional transmission electron diffraction and microscopy.
Electronic Structure and Total-Energy of FeSi2 Pseudomorphic Phases
Authors: Miglio Leo , Malegori Giovanna 
Published: September 2012

ABSTRACTBy fitting orthogonal tight binding parameters to the ab inlio bands of Calciumfluorite FeSi2 (γ-phase) and Cesiumcloride FeSi, we calculate the electronic structure (bands and density of states) and the total-energy of the semiconductive, orthorombic β-phase and the disordered, cubic one. The latter, the γ and the β nfigurations, have been recently observed at different annealing temperatures in thin films grown on Si (111) by Molecular Beam Epitaxy. The transferability of our method among different phases allows for a comparison of the cohesive energy curves which, in turn, supplies an interpretation of the relative stability and the growth kinetics.
Electrical and Optical Properties of FeSi2 Layers
Authors: Radermacher K. , Skeide O. , Carius R. , Klomfaß J. , Manti S. 
Published: September 2012

ABSTRACTWe fabricated α-FeSi2 and α-FeSi2 layers by using two methods: Ion Beam Synthesis (IBS) and Molecular Beam Allotaxy (MBA). In the latter technique a trapezoidal-shaped Fe profile was embedded in the Si matrix by codeposition of Si and Fe at temperatures of about 650°C. A rapid thermal anneal of the IBS and MBA samples at 1150°C for 10 s is necessary to obtain continuous α-FeSi2 layers. The Fe vacancy concentration of the α-FeSi2 layers was varied by a further anneal at lower temperatures. Resistivity measurements indicate a decrease of the resistivity with decreasing Fe vacancy concentration. The α-FeSi2 was transformed to a continuous β-FeSi2 layer by an anneal at 800°C for several hours. To investigate the nature of the band gap we performed absorption measurements at room temperature and 77 K. The analysis of the room temperature data revealed a direct transition at 0.84 eV and an additional indirect transition at 0.78 eV. At 77 K the direct transition shifts to ≈ 0.875 eV and the indirect to ≈ 0.86 eV.
Electric and Magnetic Transport in Ion-Beam Synthesised α-FeSi2
Authors: Larsen K. Kyllesbech , Van Hove M. , Lauwers A. , Maex K. , Rossum M. Van 
Published: September 2012

ABSTRACTMeasurements of the electrical resistivity and magnetoresistivity are reported for 100 nm buried α-FeSi2 in the temperature range 1.2 to 300 K, and in magnetic fields up to 5 Tesla.The metallic α-FeSi2 phase, formed by ion-beam synthesis and subsequent rapid-thermal annealing, is found to have a high residual resistivity of about 227 μΩ2 cm. Furthermore, a minimum in the electrical resistivity is found at 40 K. Combined with mnagnetore si stance measurements it is concluded that this minimum cannot be attributed to the Kondo effect, but is caused by weak localisation and spin-orbit interaction due to the very strong elastic scattering in the material. From the magnetoresistance measurements, at temperatures below 40 K, the relaxation times due to inelastic and spin-orbit scattering are deduced. The inelastic scattering rate is found to saturate below 4.2 K, and follow a T3 power law between 4.2 K to 40 K.
Characterization of β-FeSi2/Si Heterostructures grown by Gas-Source-MBE
Authors: Rösen B.N.E. , Freundt D. , Dieker Ch. , Gerthsen D. , Rizzi A. , Carius R. , Lüth H. 
Published: September 2012

ABSTRACTHeteroepitaxy of β-FeSi2 on (100) and (111) silicon surfaces has been achieved by gas source molecular beam epitaxy (GSMBE). Fe(CO)5 and SiH4 are used as sources for the silicide growth in the substrate temperature range 400 – 750°C. Depending on growth temperature different growth modes are observed. Concerning morphology two best temperatures were identified for the growth of β-FeSi2 on Si(111). Tg = 550°C - the epitaxial relationship with the substrate is β-FeSi2(100)||Si(111) as shown by High Resolution Transmission Electron Microscopy (HRTEM) and Low Energy Electron Diffraction (LEED); a thin γ-FeSi2 (metallic cubic phase) layer is seen to be stabilized at the interface acting as a buffer layer for the further growth of the orthorhombic semiconducting phase. Tg = 700°C - the same epitaxial relationship as in SPE grown layers is observed: β-FeSi2(101) or β-FeSi2(110)||Si(111) and no γ-FeSi2 is present at the substrate interface. In accord with the lower growth temperature, the silicide layers show slightly higher surface roughness. On Si(100) the epitaxial relationship with the substrate is β-FeSi2(100)||Si(100) in the whole temperature range. On both Si substrates domains with different azimuthal orientations are observed by LEED. In-situ electronic characterization is performed by photoelectron and electron energy loss spectroscopies. Electrical characterization at room temperature shows relatively high mobility values (up to 70cm2/Vs) but the complex temperature behaviour of the Hall constant suggests the presence of both carrier types in the β-FeSi2 grown layers. Measurements of the absorption coefficient at RT show an indirect minimum gap for β-FeSi2.
Titanium Silicides and their Technological Applications
Authors: Clevenger L.A. , Mann R.W. 
Published: September 2012

ABSTRACTTitanium silicides are used as source, gate and drain contacts and local interconnections in CMOS integrated circuits. In these applications, it is important that the titanium silicide phase have a low resistivity (< 20μΩ-cm) and not agglomerate during high temperature processing. The Ti/Si system has two silicide phases that are useful for electronic applications, high resistivity C49-TiSi2 (60-70 μΩ-cm) which forms at 600 - 700°C and low resistivity (15-20 μΩ-cm) C54-TiSi2 which forms from 700 to 850°C. This paper will review how the size of the thermal annealing process window for forming low resistivity C54-TiSi2 from high resistivity C49-TiSi2 without having the silicide agglomerate varies with annealing treatments, electronic dopants, and contact size. In addition, processing methods to improve the size of the process window will be discussed.
Formation of CoSi2 Wires by Maskless Implantation with the Focused Ion Beam
Authors: Teichert J. , Bischoff L. , Hesse E. , Panknin D. , Skorupa W. 
Published: September 2012

ABSTRACTThe maskless ion implantation with the focused ion beam as a new method for ion beam synthesis of cobalt sulicide 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.
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: September 2012

ABSTRACTHeteroepitaxial 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 silicide 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.
Ion Beam Synthesis of IrSi3 by 1-MeV Ir Ion Implantation into Si(111)
Authors: Sjoreen T. P. , Hinneberg H.- J. 
Published: September 2012

ABSTRACTThe formation of a Si/IrSi3/Si heterostructurie by 1-MeV Ir ion implantation and subsequent annealing has been studied for different doses (0.1-2.25 × 1017 Ir/cm2), substrate temperatures (450°-600°C) and annealing temperatures (1000°-1200°C) using Rutherford backscattering spectrometry, ion channeling and cross-sectional transmission electron microscopy. The heterostructure formation is observed to depend strongly on the processing conditions. The best structure, nearly continuous and precipitate-free, is obtained by implanting 1.8-2.0× 1017 1r/cm2 at a substrate temperature of 550°C and annealing at 1100°C for 5 h. A stoichiometric IrSi3 layer can also be produced by furnace annealing at 1150°C for 1 h or by rapid-thermal-annealing at 1200°C for 3 min. Other substrate temperatures generally lead to a structure with a discontinuous IrSi3 layer frequently interrupted by large surface precipitates or islands. The origin of these islands, as well as the dependence of the heterostructure on processing parameters, is discussed.
Thickness Dependence of Electrical Transport in Buried CoSi2 Films Fabricated by Ion Beam Synthesis
Authors: Radermacher K. , Jebasinski R. , Manti S. , Monroe D. , White A.E. , Short K.T. 
Published: September 2012

ABSTRACTWe have performed electrical transport measurements on thin epitaxial buried CoSi2 layers in (111) and (100)Si with thicknesses ranging from 11.5 to 110 nm. The resistivity as a function of temperature exhibits metallic behaviour. The increase of residual resistivity with decreasing thickness can be explained by quantum mechanical weak localization effects induced by the interface roughness. This is supported by magnetoresistance measurements which provide long phase coherence lengths of 1Փ, ≈ 0.75 μm in (111)Si and 1Փ, ≈ 2.3 μm in (100)Si at 4.2 K.
Study of PtSi/Si(100) Interfaces by Ballistic -Electronemission Microscopy
Authors: Turner Bruce R. , Schowalter L. J. , Lee E. Y. , Jimenez J. R. 
Published: September 2012

ABSTRACTThe PtSi/Si interface is of technological interest for Schottky barrier infrared detectors. We are studying PtSi/Si heterostructures using ballistic -electron-emission microscopy (BEEM), an STM-based technique that uses the STM tip to inject hot electrons at a particular energy into the metal overlayer. The BEEM technique allows imaging of the Schottky barrier with good spatial resolution (of the order of tens of nanometers) and allows the measurement of the hot electron attenuation length in the metal overlayer. Our results indicate a Schottky barrier of 0.87 eV for PtSi/Si n-type, and an attenuation length of 4 nm for electrons with an energy of 1 eV above the metal Fermi level. The attenuation length we measure is a convolution of the electron elastic and inelastic mean free path lengths.We have also used an ac BEEM technique to observe inelastic scattering events at the metalsemiconductor interface in PtSi/Si(100) n-type. There are several features visible in the spectrum, including one at 1040 meV which we attribute to optical phonon-assisted electron-hole pair creation near the metal- semiconductor interface in analogy to a feature we have observed at the same energy in the Au/Si(100) ac BEEM spectrum. Higher-energy features appear at 1230 meV and 1300 meV. Similar features appeared in the Au/Si(100) spectrum at 1120 meV and 1230 meV.We also suggest that the traditional assumption of momentum conservation parallel to the Schottky barrier interface is unnecessary to obtain a quadratic turn on of the BEEM current above the threshold. If electrons are elastically scattered at the interface so that momentum is not conserved, the increase in the ratio of the density of states in the semiconductor to those in the metal will also give a quadratic turn on even when the band structure is much more complicated than a nearly free electron model. This model also explains why the simple square-root dependence of the photoresponse on wavelength above threshold observed in all metal/semiconductor Schottky barriers despite the complications in band structure.
CoSi2/Si(111) Interface Structure and its Influence on the Schottky Barrier
Authors: Sullivan J. P. , Graham W. R. , Schrey F. , Eaglesham D. J. , Kola R. , Tung R. T. 
Published: September 2012

ABSTRACTThe interface structure and Schottky barrier height Of CoSi2/Si(111) interfaces may be controlled by manipulating the thin film growth conditions. Single crystal CoSi2 films on Si(111) were prepared by ultra-high vacuum processing, analyzed electrically by currentvoltage techniques, and characterized structurally by plan-view and cross-section high resolution transmission electron microscopy (HRTEM) and transm-ission electron diffraction (TED). Interfaces exhibiting n-type barrier heights ranging from 0.27 to 0.69 eV, and p-type barrier heights ranging from 0.43 eV to over 0.71 eV were prepared -by varying the processing conditions. HRTI3M and TED revealed the existence of a √3 × √3 interface reconstruction for the low barrier n-type/high barrier p-type samples. Possible models of the interface reconstruction are discussed.
Silicides for Infrared Applications
Authors: Pellegrini Paul W. 
Published: September 2012

ABSTRACTThis paper discusses the attributes of metal silicides as they are applied to detection of infrared photons. These materials have a long history in the silicon community as interconnects and are easily integrated into manufacturing. The technology is currently only sensitive to 10 μm in the infrared. New results obtained from silicon germanium alloys are discussed that will help overcome these spectral limitations.
Electrical Properties of Copper Silicide/Silicon Interfaces
Authors: Svensson B.G. 
Published: September 2012

ABSTRACTThe electrical properties of Cu/Si(100) and Cu3Si/Si(100) interfaces have been studied using both n- and p-type silicon samples. Current-voltage and capacitance-voltage measurements were performed in the temperature range 80-295 K in order to monitor Schottky barrier formation and electrical carrier concentration profiles. Deep-level transient spectroscopy was employed to observe Cu-related energy levels in the forbidden band gap of Si, and different ion beam analysis techniques were applied to study the interfacial reaction between Cu and Si. Emphasis is put on determination of Schottky barrier heights and their variation with temperature, dopant passivation by Cu atoms and interaction of Cu with irradiation-induced point defects in silicon.
Effects of Rapid Thermal Annealing on W/Si1−xGex Contacts
Authors: Aubry V. , Meyer F. , Laval R. , Clerc C. , Warren P. , Dutartre D. 
Published: September 2012

ABSTRACTThermal reaction of W with Si1−xGex films epitaxially grown by Rapid Thermal Chemical Vapor Deposition was investigated in the temperature range 500°C - 1000°C. The samples were annealed either in a Rapid Thermal Annealing (RTA) system or in a conventional furnace, both in flowing nitrogen. The reaction products were investigated by Rutherford Backscattering Spectroscopy (RBS), Energy Dispersive Spectrometry (EDS) and X-ray diffraction (XRD). Sheet resistance measurements were also performed to follow the progress of the reaction. The reaction of W with Si0.67Ge0.33 is similar to that of W with silicon. W reacts with silicon to form tetragonal WSi2. The Ge-content in the silicide is lower than that of the asdeposited alloy. It is shown that an oxygen contamination occurs during conventional annealing and leads to the formation of non homogeneous Si1−x Gex unreacted alloy below the silicide film. Rapid thermal annealing prevents this parasitic effect and the unreacted film remains homogeneous although a slight decrease in the Ge-content is observed. These results are correlated with Schottky barrier height measurements on p-Si0.83Ge0.17 partially strained films. We observed an increase of the barrier height with increasing the temperature for annealing from 500°C to 1000°C. This trend may be explained either by strain relaxation or (and) Ge-content decrease in the unreacted alloy.
Self-Aligned Formation of C54 Titanium Germanosilicide Using Rapid Thermal Processing and Application to Raised, Ultrashallow Junctions
Authors: Ashburn Stanton P. , Grider Douglas T. , ÖztÜrk Mehmet C. , Harris Gari , Maher Dennis M. 
Published: September 2012

ABSTRACTIn this paper we present results on solid state reactions between Ti and Si1−xGex alloys selectively deposited onto Si (100) substrates using rapid thermal annealing (RTA) for contact applications in novel device structures. Germanium concentrations of 0%, 30%, 50%, and 100% within the reacting Si1−xGex alloy are investigated. The Si1−xGex alloys (approximately 2500 ° thick) are deposited using rapid thermal chemical vapor deposition (RTCVD). Titanium is then deposited by evaporation. Sheet resistance measurements as a function of RTA temperature (10 second anneals) provide indications of various phases that occur during the reactions through the formation of constant sheet resistance plateaus. The RTA temperature required for the formation of a minimum resistivity phase is observed to increase for increasing Ge concentrations within the reacting Si1−xGex alloy. Using x-ray diffraction we have determined that for the reactions of Ti with Si the C49 TiSi2 metastable phase forms prior to the minimum resistivity C54 TiSi2 phase. For the reactions between Ti and Ge a minimum resistivity TiGe2 phase also with the C54 structure forms, however, this phase is preceeded not by a C49 TiGe2 structure, but by a Ti6Ge5 phase. The minimum resistivity phases for Ti reactions with 30% and 50% Ge Si1−xGex, alloy reactions also have a C54 structure with unit cell dimensions varying from that of TiSi2) to TiGe2 as the Ge concentration is increased. The grain structures for the reactions are investigated by cross-sectional transmission electron microscopy (XTEM). As the Ge concentration within the reacting alloy decreases the lateral grain size for the C54 structures increases. A self-aligned germanosilicide process is identified and used to fabricate raised, ultrashallow junctions with Ti(SiGe)2 (germanosilicide) contacts. Forward and reverse bias characterization of the junctions indicate that leakage current induced during silicidation can be eliminated using raised junctions with germanosilicide contacts.
Enhanced Relaxation of Strained GexSi1−x Layers Induced by Co/GexSi1−x Thermal Reaction
Authors: Ridgway M.C. , Rao M.R. , Baribeau J.-M. 
Published: September 2012

ABSTRACTSilicide formation on strained GexSilx layers by the thermally-induced metal/GexSi1−x reaction results in enhanced relaxation of the underlying strained layer. Silicide formation on an amorphous layer is a potential means of decreasing processing temperatures, increasing reacted-layer/GexSi1−x interface planarity and hence, decreasing strained layer relaxation. For the present report, the thermally-induced Co/Ge.17Si.83 reaction on crystalline and amorphous substrates at temperatures of 500-600°C has been compared. Though the rate of silicide formation increased with amorphous substrates, strained layer relaxation was not inhibited.