bluuebunny/crossref_metadata_2025_split huggingface dataset:
Diffusion of Gold into Heavily Boron-Doped Silicon
Authors: Bracht H. , Rodriguez Schachtrup A. 
Published: April 2011

ABSTRACTDiffusion of Au into dislocation-free and highly dislocated Si with high B-background doping levels has been investigated with the aid of neutron activation analysis in conjunction with mechanical sectioning. The high B-doping level causes extrinsic conditions, i.e., the hole concentration exceeds the intrinsic carrier concentration even at diffusion temperatures between 900°C and 1100°C. All profiles are accurately described on the basis of the kick-out diffusion model and a mechanism which takes into account segregation of Au at dislocations. Our analysis provides solubility data of Au in Si and effective diffusion coefficients related to interstitial Au and Si self-interstitials I. The dependence of these quantities on the B-background doping level is well described by the Fermi-level effect. This analysis supports singly positively charged states in p-type Si of Au on interstitial (Aui) and substitutional (Aus) sites and of Si self-interstitials. Successful fitting of additionally requires an acceptor level of Aus. The electrical properties deduced for Aui, Aus and I are summarized in Table 2. Au profiles in highly dislocated Si obtained especially after diffusion at 900° C give evidence of Au trapped at dislocations. From our preliminary experimental results we determine an enthalpy difference of 2.7 eV between Au on substitutional sites and Au captured at dislocations.
The Role of Vacancies and Interstitials in Transient Enhanced Diffusion of Arsenic Implanted into Silicon
Authors: Venables D. , Krishnamoorthy V. , Gossmann H.- J. , Lilak A. , Jones K. S. , Jacobson D. C. 
Published: April 2011

ABSTRACTBoron and antimony doped superlattices (DSLs) were implanted with arsenic at 40 keV to doses of 2×1014 cm−2, 5×1015 cm−2 and 2×1016 cm−2. Increasing the arsenic dose above 5×1015 cm−2 resulted in a reduction in the extent of arsenic transient enhanced diffusion (TED) following annealing at 700°C, 16 hr. Concurrent with this reduction in TED was a reduction in the number of free interstitials beyond the end-of-range, as measured by the boron diffusion enhancement in the doped superlattices. No enhancement in antimony diffusivity was observed in this region, indicating that vacancies play no direct role in the diffusion of arsenic in this region, although an indirect role for vacancies as recombination centers for mobile interstitials is not precluded by these experiments. We conclude that interstitials dominate arsenic diffusion in the end-of-range region and beyond. Interpretation of the DSL data in the projected range region is complicated by Fermi level and segregation effects and no definitive conclusion can be reached about the point defect populations in this region.
A PAIR-DIFFUSION MODEL FOR ARSENIC IN SILICON CONSIDERING ARSENIC DEACTTVATION-INDUCEDINTERSTITIAL-SDLICON EMISSION
Authors: Hiroi Masayuki , Ikezawa Takeo , Hane Masami , Matsumoto Hiroshi 
Published: April 2011

ABSTRACTAn arsenic diffusion model was proposed with the emphasis on a new deactivation process which accounts for excess interstitial silicon generation. Appropriate parameter set for the binding energies of arsenic-point defect pairs were obtained for reproducing various arsenic activation levels and interaction with boron in the case of co-diffusion. Such parameters were extracted from the data of carefully performed secondary ion mass spectroscopy with lowering the primary beam energy.
Detection of Metastabile Defective Regions in Ion-Implanted Silicon by Means of Metal Gettering
Authors: Kögla R. , Posselt M. , Yankov R. A. , Kaschny J. R. , Werner P. , Danilin A. B. , Skorupa W. 
Published: April 2011

ABSTRACTHigh-energy, self-ion implantation has been used to form deep gettering layers in Si. Subsequently samples have been contaminated with Cu and subjected to heat treatment. The residual defects act as gettering centres for Cu. The decoration of defects byCu making them detectable by secondary ion mass spectromety analysis. Metastable defect complexes have been detected which, because of their small size, are not directly detectable by other analytical techniques such as transmission electron microscopy and MeV-particle channeling. These defects are probably of interstitial type and have been found mainly midway between the sample and the projected ion range, i.e. around Rp/2. The gettering ability of these small defect complexes may largely exceed that of the post-anneal damage at the projected i.e range, Rp. The results obtained demonstrate that by means of metal gettering the formation, growth and dissolution of very small defect complexes in ion-implanted Si can be studied.
Identification of Microdefects in Multicrystalline Silicon
Authors: Werner M. , Möller H. J. , Wolf E. 
Published: April 2011

ABSTRACTMicrodefects in multicrystalline silicon grown by directional solidification have been investigated by transmission electron microscopy. Their density (=106 cm−2) correlates with the density of shallow etch pits observed after chemomechanical polishing and selective etching. Different types of microdefects (size 10 – 100 nm) could be identified: i) spherical precipitates most likely amorphous silicon dioxide, ii) small plates lying on {111} planes and iii) groups of closely spaced stacking faults having the character of dipoles. It is argued that these defects are the result of agglomeration process of intrinsic point defects and impurities, where oxygen and carbon are the main candidates. A qualitative comparison to the point defects agglomeration observed in Cz material will be given.
X-Ray Microanalysis of Al/Zr Multilayers in the Transmission Electron Microscope
Authors: Wall M. A. , Barbee T. W. , Bentley J. 
Published: April 2011

ABSTRACTA one-nanometer scale transmission electron microscope electron probe X-ray microanalysis characterization of as-deposited and annealed aluminum - 11.5 at.% zirconium multilayer samples in cross-section synthesized by magnetron sputtering is reported on here. Composition line profiles were acquired across Zr layers in as-deposited material and samples isochronnally annealed in a differential scanning calorimeter to temperatures of 290°C and 485°C. A spatial resolution of approximaty 1.5 to 2.0 nm was achieved in these experiments and will be improved by deconvoluti on of the instrumental electron probe function from the data. The as-deposited structure consisted of crystalline Al and Zr layers with thin amorphous layers at the Al/Zr interfaces. The amorphous interface layers increased in thickness upon annealing to 290°C. Additionally, at 290”C a metastable cubic alloy forms at the Zr deposited on Al interface. Upon heating to 485°C a multilayer of Al and metastable cubic AlxZr1-xphase is formed. The electron microscopic experimental technique, observations and data analysis will be discussed as applied to these multilayered materials.
Interfacial Reactions in Thin Film and Bulk Iron/Silicon Couples
Authors: Zhang Yuhong , Ivey Douglas G. 
Published: April 2011

ABSTRACTInitial phase formation in thin film and bulk Fe/Si couples has been investigated using transmission and scanning electron microscopy (TEM and SEM). For the thin film couples, ≈165 nm of Fe was deposited by electron beam evaporation onto <111> oriented Si substrates. SiO2 capping layers (≈100nm thick) were used to protect the Fe from oxidation during subsequent annealing. Bulk diffusion couples were fabricated by clamping together polycrystalline Fe pieces and <111> oriented single crystal Si pieces and sealed in evacuated (≈10-4 torr) quartz capsules. Annealing of thin film couples was done at temperatures ranging from 300°C to 500°C for up to several hours. Bulk couples were annealed at 700°C for up to ≈1000hrs.Interfacial reactions were detected in as deposited thin film couples. A layer =5nm thick was identified, through electron diffraction, as poorly crystalline off-stoichiometric Fe3Si. Iron was the major diffuser during the formation of Fe3Si. During annnealing off-stoichiometric Fe3Si transformed to stoichiometric Fe3Si. FeSi was the next phase to form - initially detected after annealing at 300°C for 3 hrs. Similar results were obtained for bulk couples. The first phase to form was ordered stoichiometric Fe3Si (initially detected after 7 hrs), followed by FeSi (≈23 hrs) and then FeSi2 (>200 hrs). The formation behavior of these phase is discussed.
Nucleation-Based Control of Low-Temperature Diamond Film Deposition on Optical Substrates
Authors: Gilbert Donald R. , Carasso Melanie L. , Demkowicz Paul A. , Singh Rajiv K. , Adair James H. 
Published: April 2011

ABSTRACTMicrostructural control is a critical issue in the use of diamond films in a variety of engineering applications. Using a novel, electrostatic-based particle seeding process, we have investigated the deposition of diamond films with varying areal nucleation densities. Depositions were performed at 1.000 Torr in a modified electron cyclotron resonance plasma system. Methyl alcohol was the primary diamond precursor species. SEM and Raman spectroscopy were used to evaluate microstructure and composition characteristics. Comparisons in deposition characteristics were made based on relative nucleation density.
Microstructure Evolution of Amorphous Si1-xGex Thin Films
Authors: Tong H. Y. , Jiang Q. , Hsu D. , King T. J. , Shi F. G. 
Published: April 2011

ABSTRACTThe composition dependence of the nucleation free energy barrier W* in amorphous Si1-xGex thin films is investigated. Within the composition range of x = 0.25 ∼ 0.52, the nucleation free energy barrier exhibits a maximum, which is in a good agreement with our theoretical analysis. The results are significant for processing polycrystalline SiGe thin films with desirable microstructures for thin film transistor applications. In addition, the incubation time of crystallization of amorphous Si1-xGex (x=0.5) thin films is investigated as a function of temperature.
Megasonic Irradiation Induced Chemical Reaction in the Solution
for Silicon Wafer Cleaning
Authors: Ohmi T. , Toda M. , Katoh M. , Kawada K. , Morita H. 
Published: April 2011

ABSTRACTWe have already proposed chemical vapor free and room temperature wet
cleaning (UCT cleaning) for Si substrate surface, instead of conventional
RCA cleaning, which consumes very little amount of chemicals and ultrapure
water compared to that of RCA cleaning. This new wet cleaning has been
developed by scientifically understanding contaminants removal mechanism as
follows;(1) Particles can be removed by simultaneously satisfying following two
conditions,(a) particles and substructure surface must have same polarity of zeta
potential in the cleaning solution to exhibit repulsive electric coulomb
force with each other.(b) adhered particles must be lifted off from substrate surface by slight
etching to make electric repulsive force greater than van der Waals
force,(2) Redox potential of the cleaning solution must be larger than a critical
value to enable removal of electrons from adhered metals in order to
dissolve them into the cleaning solution as positive ions and to decompose
adhered organic molecules to CO2, H2O etc.Megasonic irradiation is very essential in UCT cleaning, particularly to
remove particles by lifting them off from substrate surface. In this study,
chemical reaction in the cleaning solution induced by megasonic irradiation
is mainly discussed. Irradiation of ultrasonic having frequencies higher
than a few hundred KHz (Megasonic) to ultrapure water has been confirmed to
be able to decompose H2O molecules to H radicals and OH radicals.
Decomposition efficiency of H20 molecules is strongly dependent on remaining
gas components and their volume in the ultrapure water. When the remaining
gas volume is decreased to less than 0.2 ∼0.3ppm, H2O molecules
decomposition to H radicals and OH radicals has not been observed. Generated
OH radicals have been confirmed to produce H2O2, and
NH4+, NO2−, NO3− ions by reacting. with remaining N2 gas. Thus the
cleaning capability of the cleaning solutions can be controlled by
irradiating megasonic.
The Impact of Temperature and Concentration on SC2 Cost and
Performance in a production Environment
Authors: Riley D. J. , Glick J. S. , Parks V. , Matamis G. 
Published: April 2011

ABSTRACTRecent studies have shown that extremely dilute HCl mixtures can offer
considerable cost savings and improved particle performance relative to
traditional SC2 formulations. This work indicates, however, that extreme
levels of dilution are not necessary to secure many of the benefits
suggested for dilute HCI. Significant benefit can be attained by pursuing
moderate concentration and temperature alterations. In this study, an
intermediate dilution and temperature reduction are evaluated to assess
potential production advantage. Comparison of a 1:1:20 formulation at 60 C
is made to a more traditional 1:1:6 mixture at 85 C. The impact of the
chemistry and temperature alteration on peroxide decomposition rate is shown
to be dramatic. While initial pour-up ratios suggest that the dilute recipe
could require 1/3 as much peroxide as the traditional chemistry, chemical
savings are significantly more dramatic due to the ability of the solution
to maintain concentration over time. An additional benefit associated with
the alternative pour-up is a marked reduction in particle levels on silicon
surfaces; particle levels on thermal oxide wafers have not shown the same
trend. VPD-ICPMS measurements are used in this study to illustrate that the
recipe change results in comparable metallic removal efficiency.
A New Class of Materials with Promising Thermoelectric Properties: MNiSn (M = Ti, Zr, Hf)
Authors: Hohl H. , Ramirez A. P. , Kaefer W. , Fess K. , Thurner Ch. , Kloc Ch. , Bucher E. 
Published: April 2011

AbstractTiNiSn, ZrNiSn and HfNiSn are members of a large group of intermetallic compounds which crystallize in the cubic MgAgAs-type structure. Polycrystalline samples of these compounds have been prepared and investigated for their thermoelectric properties. With thermopowers of about –200 μV/K and resistivities of a few mΩcm, power factors S2/ρ as high as 38 μW/K2cm were obtained at 700 K. These remarkably high power factors are, however, accompanied by a thermal conductivity which is too high for applications. In order to reduce the parasitic lattice thermal conductivity, solid solutions Zrl−xHfxNiSn, Zrl−xTixNiSn, and Hfl−xTixNiSn were formed. The figure of merit of Zr0.5Hf0.5NiSn at 700 K (ZT= 0.41) exceeds the end members ZrNiSn (ZT= 0.26) and HfNiSn (ZT= 0.22).
Computational Studies of Novel Thermoelectric Materials
Authors: Singh D.J. , Mazin I.I. , KIM S.G. , Nordstrom L. 
Published: April 2011

AbstractThe thermoelectric properties of La-filled skutterudites and β-Zn4Sb3 are discussed from the point of view of their electronic structures. These are calculated from first principles within the local density approximation. The electronic structures are in turn used determine transport related quantities. β-Zn4Sb3 is found to be metallic with a complex Fermi surface topology, which yields a non-trivial dependence of the Hall concentration on the band filling. Calculations of the variation with band filling are used to extract the carrier concentration from the experimental Hall number. At this band filling, which corresponds to 0.1 electrons per 22 atom unit cell, we calculate a Seebeck coefficient and temperature dependence in good agreement with the experimental value. The high Seebeck coefficients in a metallic material are remarkable, and arise because of the strong energy dependence of the Fermiology near the experimental band filling. Virtual crystal calculations for La(Fe,Co)4Sb12 show that the system obeys almost perfect rigid band behavior with varying Co concentration, and has a substantial band gap at a position corresponding to the composition LaFe3CoSb12. The valence band maximum occurs at the Γ point and is due to a singly degenerate dispersive (Fe,Co)-Sb band, which by itself would not be favorable for TE. However, very flat transition metal derived bands occur in close proximity and become active as the doping level is increased, giving a non-trivial dependence of the properties on carrier concentration and explaining the favorable TE properties.
Structural and Optical Properties of β-FeSi2/Si(100) Prepared by Laser Ablation Method
Authors: Kakemoto H. , Makita Y. , Obara A. , Tsai Y. , Sakuragi S. , Ando S. , Tsukamoto T. 
Published: April 2011

Abstractβ-FeSi2 is a promising material for the application of various electronic, optoelectronic and energy devices. We present here the semiconducting properties of β-FeSi2 films on Si(100) substrate prepared by laser ablation method. Samples were grown using poly-crystalline bulk β-FeSi2 prepared by horizontal gradient freeze method. For the monitoring of growth, in-situ observation of ablation plume was made through fluorescence spectroscopy. Reflection of highenergy electron beam diffraction (RHEED) was also made in-situ to see the surface morphology. Characterization of the films by X-ray diffraction presented purely P3(220) orientation. Raman scattering measurements at room temperature also indicated that the grown films are semiconducting β-FeSi2. Optical absorption spectra at room temperature showed absorption coefficient higher than 105 cm−1 above the band-gap (˜1.2 eV). It was revealed that high quality semiconducting β-FeSi2 films can be fabricated by laser ablation method without post-annealing.
Thermoelectric Applications as Related to Biomedical Engineering for Nasa Johnson Space Center
Authors: Kramer C. D. , P.E.  
Published: April 2011

AbstractThis paper presents current NASA biomedical developments and applications using thermoelectrics. Discussion will include future technology enhancements that would be most beneficial to the application of thermoelectric technology.A great deal of thermoelectric applications have focused on electronic cooling. As with all technological developments within NASA, if the application cannot be related to the average consumer, the technology will not be mass-produced and widely available to the public (a key to research and development expenditures and thermoelectric companies). Included are discussions of thermoelectric applications to cool astronauts during launch and reentry. The earth-based applications, or spin-offs, include such innovations as tank and race car driver cooling, to cooling infants with high temperatures, as well as, the prevention of hair loss during chemotherapy. In order to preserve the scientific value of metabolic samples during long-term space missions, cooling is required to enable scientific studies. Results of one such study should provide a better understanding of osteoporosis and may lead to a possible cure for the disease.In the space environment, noise has to be kept to a minimum. In long-term space applications such as the International Space Station, thermoelectric technology provides the acoustic relief and the reliability for food, as well as, scientific refrigeration/freezers. Applications and future needs are discussed as NASA moves closer to a continued space presence in Mir, International Space Station, and Lunar-Mars Exploration.
Prospects for High Thermoelectric Figures of Merit in 2D Systems
Authors: Dresselhaus M. S. , Sun X. , Cronin S. B. , Koga T. , Dresselhaus G. , Wang K. L. 
Published: April 2011

AbstractEnhanced ZT has been predicted theoretically and observed experimentally in 2D quantum wells, with good agreement between theory and experiment. Advantages of low dimensional systems for thermoelectric applications are described and prospects for further enhancement of ZT are discussed.
Thermoelectric Power of Bi And Bi1−xSbx Alloy Thin Films And Superlattices Grown by MBE
Authors: Cho Sunglae , DiVenere Antonio , Wong George K. , Ketterson John B. , Meyer Jerry R. , Hoffmian Craig A. 
Published: April 2011

AbstractWe have measured the thermoelectric power (TEP) of MBE-grown epitaxial Bi and Bi1−xSbx alloy thin films and superlattices as a function of temperature in the range 20–300 K. We have observed that the TEP of a Bi thin film of 1 μm thickness is in good agreement with the bulk single crystal value and that the TEPs for superlattices with 400 Å and 800 Å Bi well thicknesses are enhanced over the bulk values. For x=0.072 and 0.088 in Bi1−xSbx thin films showing semiconducting behavior, TEP enhancement was observed by a factor of two. However as Bi or Bi1−xSbx well thickness decreases in superlattice geometry, the TEP decreases, which may be due to unintentional p-type doping.
Enhancement in Figure-Of-Merit with Superlattice Structures for Thin-Film Thermoelectric Devices
Authors: Venkatasubramanian R. , Colpitts T. 
Published: April 2011

AbstractThin-film superlattice (SL) structures in thermoelectric materials are shown to be a promising approach to obtaining an enhanced figure-of-merit, ZT, compared to conventional, state-of-the-art bulk alloyed materials. In this paper we describe experimental results on Bi2Te3/Sb2Te3 and Si/Ge SL structures, relevant to thermoelectric cooling and power conversion, respectively. The short-period Bi2Te3/Sb2Te3 and Si/Ge SL structures appear to indicate reduced thermal conductivities compared to alloys of these materials. From the observed behavior of thermal conductivity values in the Bi2Te3/Sb2Te3 SL structures, a distinction is made where certain types of periodic structures may correspond to an ordered alloy rather than an SL, and therefore, do not offer a significant reduction in thermal conductivity values. Our study also indicates that SL structures, with little or weak quantum-confinement, also offer an improvement in thermoelectric power factor over conventional alloys. We present power factor and electrical transport data in the plane of the SL interfaces to provide preliminary support for our arguments on reduced alloy scattering and impurity scattering in Bi2Te3/Sb2Te3 and Si/Ge SL structures. These results, though tentative due to the possible role of the substrate and the developmental nature of the 3-ω method used to determine thermal conductivity values, suggest that the short-period SL structures potentially offer factorial improvements in the three-dimensional figure-of-merit (ZT3D) compared to current state-of-the-art bulk alloys. An approach to a thin-film thermoelectric device called a Bipolarity-Assembled, Series-Inter-Connected Thin- Film Thermoelectric Device (BASIC-TFTD) is introduced to take advantage of these thin-film SL structures.
3.2 AND 3.8 μm Emission and Lasing in AlGaAsSb/InGaAsSb Double Heterostructures with Asymmetric Band Offset Confinements
Authors: Mikhailova M. P. , Zhurtanov B. E. , Moiseev K. D. , Imenkov A. N. , Ershov O. G. , Yakovlev Yu. P. 
Published: April 2011

AbstractWe report the first observations of electroluminescence (EL) and lasing in laser structures with high Al-content (x=0.64, Eg=1.474 eV) cladding layers and a narrow-gap InGaAsSb active layer (Eg=0.326 eV at T=77K). The structures are LPE-grown lattice-matched to GaSb substrate. Band energy diagrams of the laser structures had strongly asymmetric band offsets. The heterojunction between high Al-content layer and InGaAsSb narrow-gap active layer has a type II broken-gap alignment at 300K. In this laser structure spontaneous emission was obtained at λ=3.8μm at T=77K and λ=4.25 μm at T=300K. Full width at half maximum (FWHM) of emission band was 34 meV. Emission intensity decreased by a factor of 30 from T=77K to 300K. Lasing with single dominant mode was achieved at λ=3.774 μm (T=80K) in pulsed mode. Threshold current as low as 60 mA and characteristic temperature T0=26K were obtained at T=80–120K.