bluuebunny/crossref_metadata_2025 huggingface dataset:
Leaching of Vitrified High-Level Radioactive Waste
Authors: Hall A.R. , Hough A. , Marples J.A.C.
Published: March 2011

The work reported here is part of a study of the leaching of individual elements from waste glasses. The first part of the paper reports on leaching of the major constituents at 30°C, and leaching of the alkalis at 2°C from glass UK189; the second part describes leaching of Sr, Cs, Tc and various actinides from glasses UK189 and UK209. Compositions are given in Table 1.
Computations of Temperature Profiles in the Medium/Low-level Waste Cement and in the Rock Salt Surrounding the Disposal Cavern
Authors: Hauser W. , Smailos E. , Köster R.
Published: March 2011

Prior to disposal of cemented medium level waste and low level waste in large caverns 1000 m below ground it is important to know what temperatures will be caused by heat generation in the waste product. During the disposal period the heat produced by hydration of the cement used as the binder as well as by decaying radionuclides in the waste may give rise to inadmissibly high temperatures in the waste product resulting in a deterioration of the produc:t qualities. To avoid such undesirable processes, a maximum permissible product temperature of 90°C was specified for the investigations, i.e. a temperature that is significantly below the boiling point of the water contained in the cemented product.
Dynamic Temperature Profiles for a Uniformly Illuminated Planar Surface
Authors: Watters D. G. , Brodwin M. E. , Kriegsman G. A.
Published: March 2011

Electromagnetic heating of an infinite half space is analyzed to determine temperature distributions for constant conductivity. Both steady state and transient profiles are presented.
Estimating the Permittivity of Solids from Measurements on Granular or Pulverized Materials
Authors: Nelson Stuart O.
Published: March 2011

A procedure is outlined for determining the complex permittivity components of solid materials of known densities from those properties of granular or pulverized samples measured at a few different bulk densities. Properties of the solid are obtained by extrapolation of functions of the dielectric constant and loss factor that are linearly related to the bulk density of the air-particle mixture. Examples are given for whole-kernel wheat, ground white rice, and pulverized goethite.
Microwave Evidence for a Size-Induced Metal-Insulator Transition in Mesoscopic Conductors
Authors: Marquardt P. , Nimtz G. , Heite G. , Peters H.
Published: March 2011

Microwave investigations on sub-pm (“mesoscopic”) metal crystals revealed a size-induced metal-insulator transition (SIMIT). The microwaves were applied to determine the sizedependent quasi-static conductivity of metal crystals dispersed in an insulating matrix. Choosing an indium colloid for a model system allowed an in-situ particle size variation from 10 nm up to about 1μm. The experiments were carried out in a microwave bridge at 10 GHz, a frequency where the oscillation time is much longer than the elastic scattering time of electrons in a metal (quasi-static limit). The conductivity of metal crystals was found to decrease approximately with their volumes in the above size range. The 3-dimensional confinement of the electron wave packets gives rise to quantum-mechanical interference effects leading to the SIMIT as the crystals become smaller than 1μm. Experimental details and results including the sizeaffected temperature dependence of the conductivity are presented. The universal significance of the SIMIT and its consequences for the engineering of novel materials and the ultimate size-reduction in microelectronic devices are discussed as well.,
Microwave Dielectric Properties of Metal Filled Particulate Composites
Authors: Ho Yung Shou , Kramer John J.
Published: March 2011

Composites of metal filled particulates, Al, Cu, Si(doped), Ag and Ni, up to 45 volume percent in a polyester or epoxy matrix were made and their dielectric properties measured between 8.5 and 11.5 GHz. The particulate size was small relative to the wavelength of the microwave radiation, but in general large compared to the skin depth. For all systems the real part of the dielectric constant increases rapidly with volume fraction filler. Some correlation was also found between the dielectric constant and the average aspect ratio of the particulates, based on the number of particulates in contact. In addition particle type and size was important. The imaginary part of the dielectric constant was small except for samples that appeared to be on the verge of percolation.
Pulsed Microwave Irradiation of Graphite/Epoxy Composites
Authors: James R. B. , Bolton P. R. , Alvarez R. A.
Published: March 2011

We have measured the microwave-induced damage to the near-surface region of a graphite/epoxy composite material for 1.1-μs pulses at a frequency of 2.856 GHz and a pulse power of up to 8 MW. Rectangular samples were irradiated by single-pass TE10 traveling wave pulses inside a WR-284 waveguide, and in situ and post irradiation studies were performed to characterize the material modifications induced by the microwave pulses. The results of the time-resolved optical measurements in vacuo show that surface decomposition of the epoxy resin occurs for incident pulse powers exceeding 1.1 MW, and that the surface damage is accompanied by a large increase in the reflected microwave power. Simultaneous with the onset of surface decomposition, significant light emission from the sample and a large enhancement of the gas pressure in the test cell were observed. The large increments in both the reflected power and light emission are attributed to the formation of a plasma due to electrical breakdown of the gas at (or near) the sample surface.
Rapid Heating of Ion-Implanted Silicon by High-Power Pulsed Microwave Radiation
Authors: James R. B. , Bolton P. R. , Alvarez R. A. , Christie W. H.
Published: March 2011

We have used 1.1-μs microwave pulses at a frequency of 2.856 GHz to rapidly heat the near-surface region of arsenic-implanted silicon. The samples were irradiated inside a WR-284 waveguide by single-pass TE10 traveling wave pulses. Post-irradiation studies show that surface melting occurs for incident pulse powers exceeding about 3 MW. Time-resolved measurements of the microwave reflectivity (R) show that there is an abrupt and large increase in R for microwave pulse powers greater than the melt threshold. Significant light emission was also observed from the test cell, which is most likely due to the relaxation of a microwave-induced plasma formed by electrical breakdown of gas. Using secondary ion mass spectrometry, we measured the depth profile of the implanted arsenic and found that the penetration of the melt front in the near-surface region is not spatially homogeneous over the silicon surface.
Microwave Sintering of Boron Carbide
Authors: Katz J. D. , Blake R. D. , Petrovic J. J. , Sheinberg H.
Published: March 2011

Boron carbide has been sintered to 95% of theoretical density in less than 12 minutes without the use of sintering aides by heating to 2000°C with 2.45 GHz microwave radiation. An average grain size of about 20 μm resulted. Twins and microcracking were present in the microstructure. Energy usage for microwave sintering was found to be 18% less than for inductive hot-pressing.
Microwave Processing and Sintering of PZT and PLZT Ceramics
Authors: Harrison W. B. , Hanson M. R. B. , Koepke B. G.
Published: March 2011

Microwave processing techniques were established for all of the thermal treatment steps necessary to prepare high density PZT and PLZT. The microstructure and ferroelectric properties of the microwave processed materials were compared to conventionally sintered and fast fired PZT. Unique high density, small grain size, PZT and PLZT were obtained by microwave sintering either conventionally or fully microwave processed powders. It was estimated that microwave sintering would use only five percent of the energy used by conventional sintering.

The suitability of microwave processing for the production of two modifications (Sr and La) of lead zirconate - lead titanate (PZT) ceramics was investigated in this program. A commercial microwave oven was used to evaluate drying, calcining, binder burnoff, and sintering. These materials were then compared to those produced by fast-firing and conventional sintering methods.
Microwave Firing of High Alumina Castables
Authors: Sutton Willard H.
Published: March 2011

The potential for the microwave processing of high alumina castables was investigated*. Originally a study was conducted on the removal of the physical water from cast shapes. However, it was observed that the refractory castable material (alumina plus calcium aluminate phases) would also interact with the 2.45 GHz M/W radiation, and with proper thermal insulation it could be heated to well above 1427°C (2600°F). Full size production shapes, weighing up to 62 kg (136 lb) were heated in a 13.5 kW oven to these high temperatures. Over 1360 kg (3000 lb) of production shapes were successfully fired using M/W energy. The results of these studies are discussed along with several of the benefits which were made possible by microwave processing.
New Frontiers in the Use of Microwave Energy: Power and Metrology
Authors: Bruce Ralph W.
Published: March 2011

The Microwave/Radio Frequency portion of the electromagnetic spectrum has been used principally for the transmission and reception of information in communications and radar. With the advent of low cost commercial and consumer items (satellite downlinks and microwave ovens) has also come a resurgence of interest in using the energy and properties of these frequencies for other important tasks.

The purpose of this paper is to give a short review of the basics of electromagnetic heating and an overview of new trends in this use of microwave/RF energy. These trends can be divided into two broad categories: power and metrology.
Design Principles for High-Frequency Microwave Cavities
Authors: Kimrey H. D. , Janney M. A.
Published: March 2011

The characteristics of untuned cavities are determined for microwave processing of alumina. Alumina is a low-loss ceramic that is difficult to heat in the lower microwave region. System efficiency is determined as a function of cavity and workpiece size, frequency, and temperature. With operation at 28 GHz, a cavity applicator can be designed which is capable of generating uniform fields at high efficiency and with a reasonable size.
Temperature Characterization of Pulsed Laser Annealing of Semiconductors
Authors: Kwong D.L. , Kim D.M.
Published: March 2011

The dynamic characteristics of lattice temperature, T attained in Si under the influence of a high power laser beam irradiation are examined analytically over a wide range of laser wavelengths, pulse intensities and durations. The strongly temperature-dependent material parameters, such as optical absorption coefficient α(T) and thermal diffusivity D(T) are incorporated in heat diffusion equation, and their nonlinear coupling effect on the ensuing temperature in laser-processed semiconductors are examined. Specifically, the threshold pulse energy for surface melting is characterized as a function of both material and annealing laser beam parameters. This analytic description of pulsed laser heating of semiconductors should provide considerable insight into the transient heating phenomena and localized material modifications.
Substrate Latent Heat Effects in The Calculations for Pulsed Laser Irradiated Thin Films
Authors: Cao J.J. , Rose K. , Aina O. , Katz W. , Norton J.
Published: March 2011

We present a numerical model for the calculation of the temperature rise caused by pulsed laser irradiation of a thin film/substrate structure. This model includes phase changes in both the thin film and the substrate. The inclusion of phase changes results in more complex thermal behavior and significantly affects melt durations. This model was applied to the AuGe/GaAs system. Morphological observation using the scanning electron microscope and SIMS profiles provides experimental verification for the numerical calculations.
Solid-Phase-Epitaxial Growth of Ion Implanted Silicon Using CW Laser and Electron Beam Annealing
Authors: Narayan J. , Holland O. W. , Olson G. L.
Published: March 2011

The nature of residual damage in As+, Sb+, and In+ implanted silicon after CW laser and e− beam annealing has been studied using plan-view and cross-section electron microscopy. Lattice location of implanted atoms and their concentrations were determined by Rutherford backscattering and channeling techniques. Maximum substitutional concentrations achieved by furnace annealing in a temperature range of 500–600°C have been previously reported [1] and greatly exceeded the retrograde solubility limits for all dopants studied. Higher temperatures and SPE growth rates characteristic of electron or cw laser annealing did not lead to greater incorporation of dopant within the lattice and often resulted in dopant precipitation. Dopant segregation at the surface was sometimes observed at higher temperatures.
Raman Scattering with Nanosecond Resolution During Pulsed Laser Heating of Silicon
Authors: Von Der Linde D. , Wartmann G. , Ozols A.
Published: March 2011

We present time-resolved measurements of spontaneous anti-Stokes and Stokes Raman scattering during pulsed laser heating of crystalline silicon. The time-evolution of the lattice temperature is determined from the measured anti-Stokes/Stokes intensity ratio. In a separate calibration experiment we measure the temperature dependence of the anti-Stokes/Stokes ratio of an oven-heated silicon crystal from 300 K up to 900 K. The phase transition occuring during laser heating is detected by monitoring the changes of the optical reflectivity during laser irradiation. Our data suggest that the phase transition occurs at a lattice temperature of ∼600 K.
Explosive Recrystallization Of Ion Implantation Amorphous Silicon Layers
Authors: Narayan J. , Rozgonyi G. R. , Bensahel D. , Auvert G. , Nguyen V. T. , Rai A. K.
Published: March 2011

Explosive recrystallization of amorphous layers, induced by scanned electron or CW Ar+ laser beams, has been investigated in arsenic implanted (100) specimens. We have studied the microstructural changes using plan-view and crosssection electron microscopy to obtain the mechanism of explosive recrystallization phenomenon. The confinement of heat in the amorphous layers during laser irradiation and the nature of amorphous silicon determine the modes of explosive recrystallization. We indicate that, depending upon the degree of undercooling, two distinct modes of liquid-phase recrystallization are observed: one occurring at a velocity of, ∼2 ms−1 and the other at ∼10ms−1. Explosively recrystallized grains contain <110> and <110> as surface normal and growth direction respectively. We present a model for unseeded crystallization to explain the <110> texture observed in diamond cubic lattices.
Visualization of Temperature Profiles in a-Si Crystallized in the Explosive Mode by Ow Laser.
Authors: Rivier Michel , Cserhati Andras , Goetz George
Published: March 2011

We present an experimental method, based on the isothermal nature of the boundaries of explosively crystallized silicon, to display instantaneous isotherms produced by fast scanning laser beams. This method is especially useful for the case of multilayer structures or complex geometries, where thermal profiles simulation is a difficult problem. We can also obtain directly a measure of the spatial intensity distribution in the laser beam.
Picosecond Laser-Induced Surface Transformations in Solids
Authors: Fauchet P.M. , Guosheng Zhou , Siegman A.E.
Published: March 2011

We report the results of a study of surface transformations in semiconductors (Si, GaAs) and metals (Cu) produced by 100 ps long pulses from a Nd:YAG laser system. We present and outline the conclusions of our model for growth of spontaneous periodic surface structures or ripples often associated with laser damage and annealing. The effect of repetitive subthreshold illumination is also examined. Theoretical analysis is presented to support time-resolved experiments performed with two excitation pulses at different wavelengths.
Aligned, Coexisting Liquid and Solid Regions in Pulsed and CW Laser Annealing of Si
Authors: Nemanich R. J. , Biegelsen D. K. , Hawkins W. G.
Published: March 2011

Aligned, coexisting liquid and solid regions are observed in cw laser annealing of polycrystalline Si films on quartz substrates. These stripe patterns are the precursors of surface topography that exists after cooling. It is proposed that a similar situation exists in the pulse annealing process. A calculation of the temperature evolution which assumes stripe symmetry and kinetic restraints of the crystallization process has been carried out. These calculations indicate a lattice temperature of between 1100 and 1300 K, 10 nsec after the sample has fully solidified.
Interferometric Measurements of Surface Properties During Laser Annealing
Authors: Bertolotti Mario , Ferrari Aldo , Sibilia Concetta , Jani Peter
Published: March 2011

A simple interferometric method is presented which allows measurement of small vertical displacement of a surface heated by a laser beam. Calculations applied to a silicon crystal in the case of a c.w. laser show reasonable agreement with experiment. The method can be applied to assess surface temperature and thermal constants.
Pulsed Raman Measurements of Phonon Populations: Time Reversal, Correction Factors, and All That
Authors: Compaan A. , Lo H.W. , Aydinli A. , Lee M.C.
Published: March 2011

Transient optic phonon populations are measured in crystalline Si as a function of 532 nm laser energy density. The use of a continuously tunable pulsed dye laser as the Raman probe allows us to obtain, under exact experimental conditions, all correction factors necessary to extract the phonon population without the necessity of relying on room temperature or oven-heated conditions. We find the shift of the 520 cm−1 Raman-line to be consistent with the observed Stokes/anti-Stokes ratios indicating a maximum optic phonon temperature of 450 ± 100°C. A discussion is also given of the errors in several recent criticisms of the Raman results.
Coherent Precipitate Formation In Pulsed-Laser And Thermally-Annealed,
Ion-Implanted Si.*
Authors: Appleton B. R. , Narayan J. , Holland O. W. , Pennycook S. J.
Published: March 2011

It Will be shown that under suitable conditions ion implanted impurities in Si can precipitate and grow coherently within the single crystal lattice during recrystallization induced by pulsed laser or thermal annealing. Ion channeling and transmission electron microscopy (Tem) were used to characterize such precipitates in Si implanted with Sb and B and thermally annealed, and in Si implanted with Tl and annealed with a pulsed ruby laser.The orientations of these precipitates were determined from TEM and detailed angular scans using ion scattering channeling.The nucleation and precipitation processes will be discussed in terms of differences in the liquid and solid phase regrowth mechanisms.
Pulsed Laser Annealing of Ion Implanted Ge
Authors: Holland O. W. , Arayan J. , White C. W. , Appleton B. R.
Published: March 2011

Ion backscattering/channeling and transmission electron microscopy (TEM) were used to investigate the annealing behavior of ion implanted Ge single crystals using a Q-switched ruby laser. The impurities studied were Bi, In, Sb and Pb, which were implanted at liquid nitrogen temperature into both (100) and (111) crystal orientations. A rather unique damage structure which can form during room temperature implantation of Ge is discussed. Maximum substitutional concentrations, which far exceed the retrograde maxima, are reported for all the dopants studied in (100)Ge. The maximum concentrations were limited by an interfacial instability during epitaxial growth following laser irradiation which led to the formation of a well-defined cellular structure.
Picosecond Time-Resolved Detection of Plasma Formation and Phase Transitions in Silicon
Authors: Liu J. M. , Kurz H. , Bloembergen N.
Published: March 2011

Picosecond time-resolved reflectivity and transmission changes of bulk silicon and silicon-on-sapphire have been measured to study the electron-hole plasma formation and phase transitions in silicon, induced by picosecond green or ultraviolet pulses. The results provide direct evidence of ultrafast energy transfer to the lattice and ultrafast phase transitions in silicon. Lattice heating up to the melting point and overheating of the melt or boiling have been observed during the picosecond pulse duration.
Surface Studies of Laser Annealed Semiconductors
Authors: Zehner D. M. , White C. W.
Published: March 2011

The surface regions of semiconductor single crystals have been examined following laserannealing in an ultrahigh vacuum environment with the output of a pulsed ruby laser. Atomically clean surfaces with impurity levels below 0.1% of a monolayer can be produced by multiple pulse irradiation. Ordered surface structures are produced on low index oriented crystals as well as crystals slightly misoriented. Metastable surface structures exhibiting (l×1) LEED patterns have been produced on (111) orientations and are believed to be a consequence of the rapid cooling rates of 109 degs/sec achieved with the laser irradiation process. The surface and subsurface regions of ion-implanted Si crystals have been examined both before and after laser irradiation and results obtained from Si samples implanted with As are discussed.
Applications of Laser Annealing in IC Fabrication
Authors: Hess L.D. , Eckhardt G. , Kokorowski S.A. , Olson G.L. , Gupta A. , Chi Y.M. , Valdez J.B. , Ito C.R. , Nakaji E.M. , Lou L.F.
Published: March 2011

Laser annealing is discussed in the context of potential applications in the fabrication of advanced solid state components and integrated circuits. General aspects of the uniquetemporal and spatial heating distributions that can be obtained with laser heating are presented, and selected examples are given which illustrate the advantage of special time/temperature heating cycles in the processing of specific semiconductor device structures. The performance of silicon and Hgcdte diodes, polysilicon resistors, multiple stacked polysilicon/oxide capacitors, Al/Si ohmic contacts and MOS/SOS transistors fabricated using laser annealing is significantly improved relative to devices fabricatedusing conventional furnace annealing.
Rapid Thermal Annealing of Silicon Using an Ultrahigh Power Arc Lamp
Authors: Hodgson R. T. , Baglin J. E. E. , Michel A. E. , Mader S. , Gelpey J. C.
Published: March 2011

We have used an ultrahigh power, 100kW vortex cooled arc lamp to anneal As+ implant damage in <100> silicon wafers. When the wafer temperature was held above 1100°C for ∼1sec, TEM analysis indicated that the material was free of extended defects.The dopant diffused much more rapidly than would be expected from the usual models. However, preliminary results indicate that defect free material can be produced with dopant movement limited to ∼100Å.
Flame Annealing of Ion Implanted Silicon
Authors: Narayan J. , Young R. T.
Published: March 2011

We have investigated flame annealing of ion implantation damage (consisting of amorphous layers and dislocation loops) in (100) and (111) silicon substrates. The temperature of a hydrogen flame was varied from 1050 to 1200°C and the interaction time from 5 to 10 seconds. Detailed TEM results showed that a “defect-free” annealing of amorphous layers by solid-phase-epitaxial growth could be achieved up to a certain concentration. However, dislocation loops in the region below the amorphous layer exhibited coarsening,i.e., the average loop size increased while the number density of loops decreased. Above a critical loop density, which was found to be a function of ion implantation variables and substrate temperature, formations of 90° dislocations (a cross-grid of dislocation in (100) and a triangular grid in (111) specimens) were observed. Electrical (Van der Pauw) measurements indicated nearly a complete electrical activation of dopants with mobility comparable to pulsed laser annealed specimens. The characteristics of p-n junction diodes showed a good diode perfection factor of 1.20–1.25 and low reverse bias currents.
Isothermal Annealing of Ion Implanted Silicon With a Graphite Radiation Source
Authors: Wilson S. R. , Gregory R. B. , Paulson W. M. , Hamdi A. H. , Mcdaniel F. D.
Published: March 2011

Both (100) and (111) Si wafers were implanted with As, P or B to doses from 1013 to 1016/cm2 and annealed with a Varian IA-200 isothermal annealer. The anneal occurs in a vacuum using infrared radiation for exposure times of 5 to 30 sec. Sheet resistance (Rs), Hall effect, RBS and SIMS were used to analyze the wafers. For each dopant a decreasing Rs occurs with increasing exposure time until a minimum value is reached. Longer anneals produce increased dopant diffusion, and the Rs for As and P implanted wafers increased unless the wafer was capped with 0.05 μm of SiO2 which prevents a loss of dopant. The results for (100) wafers are better than for (111) with As doses ≤1015/cm2, however at doses >1015/cm2 the (100) and (111) results are comparable. The As implanted, isothermally annealed layers were thermally stable for As concentrations ≤2E 20/cm3.
Gettering of Impurities by Incoherent Light Annealed Porous Silicon
Authors: Borisenko V. E. , Dorofeev A. M.
Published: March 2011

The application of electrochemically formed porous silicon to getter Cu and Au atoms in silicon crystals during incoherent light annealing for 4 to 20 sec is reported. Exposure light power density of 30 W/cm2 was used to heat the samples up to 950 °C. Improvement of lifetime related to Au and Cu gettering with porous silicon has been observed. Excess impurity interstitials and their enhanced diffusion are supposed to be responsible for the gettering effect.
Instability of The Electron-Hole Plasma and its Possible Relation With Melting
Authors: Combescot Monique , Bok Julien
Published: March 2011

We show that the softening of the T.A. phonon mode produces an instability in the electron-hole plasma of a silicon-like semiconductor and suggest that this instability can be the mechanism for melting of this type of material. This allows us to estimate the characteristics of a laser pulse which are necessary to modify the usual melting, i.e. which would lead to a substantial decrease of the melting temperature.
Scanning Eectron Beam Annealing of Oxygen Donors in Czochralski Silicon
Authors: Pollard C J , Speight J D , Barraclough K G
Published: March 2011

The destruction of the oxygen donor complex in Czochralski silicon has been studied using scanning electron beam annealing in the range 550°C to 1050° C for 5s to 1000s. A two stage annealing schedule ensured a rapid rise to the target temperature and overscanning provided a uniform, non-distorting heating field. Four point probe and spreading resistance measurements showed a very rapid donor destruction rate above 650° C; between 550° C and 650°C the lower donor destruction rate allowed a study of the annealing behaviour.
Arsenic Implant Activation and Redistribution in P-Type Silicon Induced by Pulsed Electron Beam Annealing
Authors: Barbierf D. , Baghdadi M. , Laugier A. , Cachard A.
Published: March 2011

In this work Pulsed Electron Beam Annealing has been used to Sctivaye As implanted in (100) and (111) silicon (140 keV- 1015 cm−2 ). With a selected electron beam energy deposition profile excellent regrowth layer quality and As activation has been obtained in the 1.2–1.4 J/cm2 fluence range. As redistribution is conistent with the melting model assuming a diffusivity of 10−4 cm2/s in liquid silicon. As losses might slightly reduce the carrier concentration near the surface in the case of (100) silicon. However a shallow and highly active N+ layer have been achieved with optimized PEBA conditions.
Transient Annealing of Ion-Implanted Silicon Using A Scanning IR Line Source
Authors: Liu Y.S. , Cline H.E. , Possin G.E. , Parks H.G. , Katz W.
Published: March 2011

Recent interest in finding an efficient method for transient annealing of ion-implanted silicon has led to studies of various rapid annealing schemes such as graphite heaters and high intensity incoherent light sources as alternative methods to laser annealing. In this paper, we describe a recent study of transient annealing of ion-implanted silicon using a scanning IR line source created by a single tungsten filament enclosed in a quartz envelope. Various dopants (B+, P+ and As+) with fluences of 1014 to 1016 ions/cm2 were implanted and annealed under both transient and steady-state thermal conditions. Dopant depth distributions were analyzed using the SIMS technique. Sheet resistance measurements indicated that almost 100% activations of the implanted dopants were achieved. Sensitivities of dopant activation to transient annealing conditions were studied as a function of dopant concentrations, and high-dose As- and B-implanted samples were found to be sensitive to transient thermal cycle, particularly to the peak temperature. Recrystallization was studied with Rutherford backscattering spectroscopy using 2 Mev He+ ions.
Conduction in Polycrystalline Silicon: Generalized Thermionic Emission-Diffusion Theory and Extended State Mobility Model
Authors: Khondker A.N. , Kim D.M. , Shah R.R.
Published: March 2011

We present a general theory of conduction in polysilicon. The theoretical framework reconciles two apparently divergent approaches for modeling conduction processes in polysilicon and provides a physical basis to correctly interpret and to point out the deficiencies of previously reported thermionic and thermionic field emission theory. This model is based on an extended state mobility in the disordered grain boundary and the thermionic emission-diffusion theory for conduction of current. The attractive features of our theory are (a) it can explain the experimental data without the use of an artificial factor, f, (b) the conduction process is characterized explicitly by the inherent material properties of the grain and the grain boundary. Our model is particularly suited for describing the electrical properties of laser restructured polysilicon, where because of large grain size the diffusion process is expected to be dominant.
Selective Laser Annealing For Device Processing
Authors: Calder I.D. , Naem A.A. , Naguib H.H.
Published: March 2011

Selective laser crystallization of undoped polysilicon films has been achieved through the use of a patterned Si3N4 anti-reflection (AR) coating. The recrystallized poly-Si beneath the AR cap exhibits an etch rate 50–90% lower than the surrounding uncapped material, allowing anisotropic etching of poly-Si for the fabrication of MOSFET gates. Undercut is reduced by at least a factor of two from unannealed material. Annealed edge profiles are uniform within ±0.03μm for plasma etching (±0.05 for wet etching) compared to ±0.1μm (± 0.25μm for wet etching) for unannealed regions. The sheet resistivity of 0.5μm films doped by phosphorus diffusion was reduced from an initial value of 82±5 Ω/□ to 40±8 Ω/□ when the dopant was diffused into recrystallized poly-Si and to a final value of 10.2 ± 0.2 Ω/□; after a further laser activation step. Potential applications in VLSIC processing are discussed.
Crystallization of Amorphous Silicon Films by Pulsed Ion Beam Annealing
Authors: Gyulai J. , Fastow R. , Kavanagh K. , Thompson M. O. , Palmstrom C. J. , Hewett C. A. , Mayer J. W.
Published: March 2011

Regrowth by pulsed proton beam was studied for evaporated amorphous Si layers, for layers converted to polycrystalline by annealing (both with and without Ge markers) and for implantation-amorphized SOS films. Silicon-on-sapphire showed the lowest threshold for regrowth. Amorphous silicon melted at about 0.2 J/cm2 lower fluences of protons of 380 kev energy than crystalline Si. Implanted Sb into Sos occupies lattice positions exceeding the solid solubility.
Detection of Electronic Defects in Strip-Heater Crystallized Silicon Thin Films
Authors: Johnson N. M. , Moyer M. D. , Fennell L. E. , Maby E. W. , Atwater H.
Published: March 2011

Electronic defects in strip-heater crystallized silicon thin films have been investigated with capacitance-voltage (C-V),deep-level spectroscopic, and scanning-electron microscopic techniques. For electrical characterization the crystallized silicon films were used to fabricate inverted metal-oxide-silicon capacitors in which degenerately doped bulk silicon substrates provided the gate electrode. High-frequency C-V characteristics yield effective fixed-charge densities in the oxide of ≤ 2×1011 cm−2. Trap-emission spectra, recorded with deep-level transient spectroscopy on both p-type and n-type capacitors, indicate a continuous distribution of deep levels throughout the silicon bandgap. The Si-SiO2 interface is considered to be the principal source of this deep-level continuum, since the films are essentially single crystal with a low density of subgrain boundaries; the effective interface-state density is ≤ 2.5×1010 eV−1 cm−2. A discrete energy level, detectable above the background continuum,appears in the upper half of the silicon bandgap; it may identify a point defect in the bulk of the silicon film with a spatially uniform density of approximately 1×1013 cm−3. On lateral p-n junction diodes, electron-beam-induced-current images reveal enhanced diffusion of arsenic along structural defects intersecting the junction.
Characterization and Application of Laser Induced Seeded-Lateral Epitaxtal Si Layers on SiO2
Authors: Miyao M. , Ohkura M. , Warabisako T. , Tokuyama T.
Published: March 2011

Electrical and crystal properties of seeded lateral epitaxial Si are evaluated as a function of distance from seeding area with the aid of a micro-probe RHEED and MOSFET fabrication. the results indicate that the quality of a grown layer is as good as that of bulk Si Crystal for most of the epitaxial layer. However, at the SiO2 edge, electrial properties are somewhat poor due to the existence of dislocation and residual stress.Element devices useful for SO structures are fabricated. Electrical properties of MOSPET's with double active areas indicate that surface and bottomregions of the epitaxial layer are all of device worthy quality.Insulated control gate bipolar type transistors are proposed and some preliminary results are shown.
Measurement of Fast Melting and Regrowth Velocities in Picosecond Laser Heated Silicon
Authors: Bucksbaum P. H. , Bokor J.
Published: March 2011

Fast regrowth of amorphous silicon from liquid silicon films has been directly observed in a time resolved picosecond laser melting experiment. Liquid films up to 100 nm thick were formed on crystalline substrates with 15 picosecond 248 nm pulses from a KrF* excimer laser. The film thickness as a function of time was probed directly by observing attenuation of 1.64 pm 15 psec light pulses transmitted through the melt. Melting and regrowth velocities were compared to a heat diffusion model, and evidence for melt undercooling was observed. The resolidified silicon was amorphous at all values of incident laser intensity.
Cw Laser Annealing of Ion Implanted Oxidized Silicon Layers on Sapphire
Authors: Alestig G. , HolmÉn G. , Peterström S.
Published: March 2011

CW laser annealing has been performed on silicon on sapphire (SOS) implanted with boron or phosphorus ions to a dose of 1015 ions/cm2 . The laser irradiation was done both with and without an oxide layer on top of the silicon and from both the silicon and the sapphire side. Sheet resistivity and Hall effect measurements were used for the analysis of the samples. Good annealing and high activation of the dopants were obtained for both oxidized and unoxidized SOS. For samples irradiated from the silicon side, the needed laser power changed depending on the thickness of the oxide. For samples irradiated from the sapphire side, the needed laser power was independent of oxide thickness.
The Effects of Selectively Absorbing Dielectric Layers and Beam Shaping on Recrystallization and Fet Characteristics in Laser Recrystallized Silicon on Amorphous Substrates
Authors: Possin G. E. , Parks H. G. , Chiang S. W. , Liu Y. S.
Published: March 2011

Selective absorption, using patterned dielectric films, and beam shaping were used as means for improving the recrystallization of LPCVD polysilicon islands on fused quartz. IR imaging of the laser heated region was used to optimize and control the recrystallization. MOSFETs were fabricated in laser-recrystallized silicon islands on amorphous substrates using a standard n-channel poly-gate process. Devices with various channel lengths and widths were fabricated, and the dependence of threshold voltage, channel mobility, and leakage on recrystallization conditions and device dimensions was studied.
Growth of Silicon-on-Insulator Films using a Line-Source Electron Beam
Authors: Knapp J. A. , Picraux S. T.
Published: March 2011

A swept line-source electron beam has been used to study unseeded Si-on-insulator crystallization at beam scan speeds of 150–1500 cm/s. For a particular sample configuration a maximum linear crystallization velocity of ~ 350 cm/s was observed. At higher sweep speeds, competing nucleation occurred at intervals across the film. Both the limit in crystallization velocity and the intervals between nucleation are tentatively explained by a simple model.
Time Resolved Measurements of Interface Dynamics During Pulsed Laser Melting Observed by Transient Conductance
Authors: Thompson Michael O. , Galvin G. J.
Published: March 2011

The transient conductance technique has been used in a detailed study of the liquid-solid interface dynamics during pulsed laser melting of Si and silicon-on-sapphire. Average melt and regrowth velocities, as well as the maximum melt depth, can be obtained with the technique. The measurements are found to agree well with a computer simulation based on a thermal model of the melt and subsequent solidification. The melt-in velocity has been observed to exceed 200 m/sec. Under 2.5 ns UV irradiation, the critical velocity for amorphization of <100> Si has been measured at 15 m/sec.
Lateral Epitaxial Growth of Thick Polysilicon Films on Oxidized 3-Inch Wafers
Authors: Celler G. K. , Robinson Mcd. , Lischner D. J. , Sheng T. T.
Published: March 2011

Recently we reported the first successful crystallization from the melt of 15,μm thic Si films on SiO2. In this technique of Lateral Epitaxial Growth over Oxide (LEGO), crystallization is initiated at seeding vias in SiO2 and propagates over the amorphous insulator, resulting in high structural quality of the grown film. Uniform and bow-free crystallization of complete 3-inch wafers occurs in <60 sec in a special furnace, with wafers placed between a bank of high intensity tungsten halogen lamps and a water cooled base.

In this paper we provide further details of crystallization procedure and new structural characterization data. The mechanism of LEGO crystallization and its limitations are also discussed.
Crystallization of Silicon Films on Glass: A Comparison of Methods
Authors: Lemons Ross A. , Bosch Martin A. , Herbst Dieter
Published: March 2011

The lure of flat panel displays has stimulated much research on the crystallization of silicon films deposited on large-area transparent substrates. In most respects, fused quartz is ideal. It has high purity, thermal shock resistance, and a softening point above the silicon melting temperature. Unfortunately, fused quartz has such a small thermal expansion that the silicon film cracks as it cools. This problem has been attacked by patterning with islands or moats before and after crystallization, by capping, and by using silicate glass substrates that match the thermal expansion of silicon. The relative merits of these methods are compared. Melting of the silicon film to achieve high mobility has been accomplished by a variety of methods including lasers, electron beams, and strip heaters. For low melting temperature glasses, surface heating with a laser or electron beam is essential. Larger grains are obtained with the high bias temperature, strip heater techniques The low-angle grain boundaries characteristic of these films may be caused by constitutional undercooling. A model is developed to predict the boundary spacing as a function of scan rate and temperature gradient.
Electrical Defect Analysis Following Pulsed Laserirradiation of Unimplanted GaAs
Authors: Pribat D. , Delage S. , Dieumegard D. , Croset M. , Srivastava P.C. , Bourgoin J.C.
Published: March 2011

Current-voltage, capacitance-voltage and defect spectroscopy techniques are used to characterize the electrical properties of GaAs crystals after pulsed laser irradiation with either a Nd-YAG or a Ruby laser. I(V) and C(V) measurements performed in conjunction on Au/GaAs Schottky structures after laser irradiation at low energy density show an important barrier lowering, of the order of 300mV. Carrier compensation up to 6×lO16/cm3 is observed in a subsurface layer whose thickness increases with deposited laser energy density. D.L.T.S. is used to study the tail of laser induced defects behind the heavily compensated layer. Finally the results are compared to those obtained following conventional thermal treatment.
Transient Conductivity Measurements in Pulsed Ion Beam Melted Silicon
Authors: Fastow R.M. , Gyulai J. , Mayer J.W.
Published: March 2011

A pulsed proton beam, ˜200 ns in duration, has been used to melt and regrow single crystal silicon. The protons had an energy of 300 kev, yielding a measured energy density of 0.8–2.0 J/cm2. The method of transient conductivity has been used to determine the melt depths, melt durations, and regrowth velocities. The measured values for 2.0 J/cm2 were, respectively, 1.7 μm, 2 μsec, and 1.4 m/sec.

Computer generated melt curves were compared to experiment with good agreement. The energy required to initiate melt was determined, and a linear dependence of melt depth with energy has been observed.
Pulsed Proton Beam Annealing of Co-Si Thin Film Systems
Authors: Chen L. J. , Hung L. S. , Mayer J. W. , Baglin J. E. E.
Published: March 2011

Cobalt (∼300Å) and CoSi2 (∼1000Å) thin films on Si have been annealed by intense proton beams. RBS and TEM were performed to study ion beam annealing effects.

For ion beam energy densities above about 1 J/cm2, epitaxial CoSi2 layers were formed for both Co and polycrystalline CoSi2 on Si. At low energy densities, Co2Si was found to coexist with Co. The results are discussed in terms of eutectic melting processes.
Submicron Conductor Array Fabricated from a Recrystallized Eutectic Thin Film
Authors: Cline H. E.
Published: March 2011

A submicron conductor array was fabricated without using lithography by selectively etching a recrystallized A1-A12Cu eutectic alloy thin film. The 2 micron thick eutectic films were deposited on glass substrates and directionally solidified with both a quartz-iodine lamp and a scanning laser at rates between .0016 and .14 cm/sec. The resulting structure consisted of alternate parallel stripes of the two eutectic phases with a spacing between .5 and 4 microns that was controlled by the solidification rate. An array of submicron Al- rich conductors was fabricated by selectively etching away the Al2 Cu phase. At solidification rates greater than .004 cm/sec using the lamp heater the solid-liquid interface became non-planar while with the laser the structure was well alligned at the highest rates used, .14 cm/sec. At the maximum theoretical solidification rate that produces a two phase aligned eutectic structure the width of the Al wires would be 100A.
Amorphous Phase Trapping as a Result of Pulsed Laser Irradiation of Silicon
Authors: Wood R. F.
Published: March 2011

It is concluded that large interface undercoolings of ˜ 300 deg are not likely to occur during pulsed laser annealing and that the observed liquid to amorphous phase transition is not a purely thermodynamic effect. It is then shown that the formation of the amorphous phase can be understood on the basis of a kinetic rate model which makes large undercoolings of the interface unnecessary.
Testing Fly Ash for Fineness to ASTM C 430: Sieve Calibration
Authors: Butler W. Barry , Kanare Howard M.
Published: March 2011

Following dissatisfaction with the existing calibration factor for standard fly ash used in Australia to AS 1129–1971, “Fly Ash for Use in Concrete,” a joint investigation was made by Amatek Limited and Construction Technology Laboratories Inc. Test results for five reference materials and two Australian fly ashes from tests to ASTM C 430 on both electroformed and woven wire sieves were examined and “corrected” by several means.

The ASTM standard method of sieve correction is challenged, both in the use of Standard Reference Material (SRM) cement and the basis of sieve correction for coarse samples. Preferred bases of correction are suggested.
Investigations on the Composition of Individual Fly Ash and CFB-Ash Particles
Authors: Odler I. , Zysk K.-H.
Published: March 2011

The individual particle compositions of three circulating fluidized bed combustion (CFB) ashes and one Type C fly ash were studied to determine differences in composition existing between the individual particles within a single ash. The methods used for the investigation included optical microscopy, XRD and XRF analysis. It was found that all the ashes studied consisted of several types of particles that differed in morphology, color and composition.
Storage Alternatives for High-Calcium Fly Ashes
Authors: Kilgour Carol L. , Bergeson Kenneth L. , Schlorholtz Scott
Published: March 2011

One of the major problems currently restricting the utilization of high-calcium (ASTM Class C) fly ashes in Iowa is lack of adequate storage space. High-calcium fly ashes are self-cementitious and are generally not economically reclaimable once they have been exposed to water (i.e., the environment). Since the on-site silo storage capacity of a given power plant is normally only about one or two weeks of overall generating capacity (assuming nearly full load), the fly ash industry is hard-pressed to meet the demand for fly ash during the peak construction months.

This paper presents some early research findings concerning the storage alternatives available for these high-calcium fly ashes. A simple pan agglomerator, requiring only the addition of a water spray was used to produce fly ash pellets. Since the method required minimal energy input the process would be expected to be economically feasible for field production. Laboratory produced pellets appeared strong and durable and would be expected to withstand field handling without significant degradation. The pelletization process did not appear to result in a loss of reactivity for either the air-dried or water-cured pellets. This is highly important for potential use in Portland cement concrete or soil stabilization.