bluuebunny/crossref_metadata_2025_split huggingface dataset:
Microstructural Control through Diffusion-Induced Grain Boundary Migration
Authors: Handwerker Carol A. , Cahn John W. 
Published: March 2011

ABSTRACTDiffusion-induced grain boundary migration (DIGM) is a common, but only recently discovered low temperature phenomenon that results in high rates of both chemical mixing (or unmixing) and grain boundary migration. DIGM is found in many situations where chemical heterogeneities lead to diffusion. For example, DIGM is observed during diffusion and compound formation in polycrystalline multilayer contact systems produced by low temperature deposition techniques. The diffusional mixing along the moving grain boundary is high, localized, and results in a distinctive composition profile behind the moving interface. Theory has indicated, and experiments have confirmed, which conditions lead to DIGM and which conditions suppress it. The microstructural changes can result in either a grain refinement as seen in many metallic systems or in enhanced grain growth as seen in polysilicon. In either case these microstructural and compositional changes are controllable in a way that may allow fabrication of unique devices.
A TEM Study of the Structure of Polycrystalline Si Films on (111) Si Substrates Grown by Low Pressure Chemical Vapor Deposition
Authors: Piette Scott A. , Kiely Chris J. , Eden J. Gary 
Published: March 2011

ABSTRACTA systematic series of films have been deposited on Si (111) wafers by the pyrolytic decomposition of disilane in a low pressure CVD reactor at temperatures below 765°C, at a variety of Si2H6 partial pressures. Usually, large columnar Si grains nucleate with the [110] fiber axis parallel to the [111] substrate normal, and exhibit a random arrangement of azimuthal orientations about this axis. Fine scale microtwinning and sub-grain boundaries which are often seen within individual columnar grains have been characterized by HREM. The facetted boundaries between individual columnar grains have also been characterized. The correlation between typical grain size, defect densities and Si2 H6 partial pressure is presented and the effect of changing partial pressure during growth is shown to be detrimental to film quality. Finally it is noted that randomly oriented polycrystalline Si films can be formed under certain growth conditions.
Low Temperature Oxidation of PTSI on As-Doped Si
Authors: Gambino J. P. , Cunningham B. , Turene F. E. , Shepard J. F. 
Published: March 2011

ABSTRACTPtSi on As-doped polysilicon oxidizes rapidly at temperatures as low as 500 °C. The resulting SiO2-PtSi and PtSi-polysilicon interfaces are very rough. Silicide inclusions are present in the oxide, probably due to differences in oxidation rate between different PtSi grains. The presence of some inclusions near the SiO2 surface suggests that PtSi dissociates during oxidation. Rapid oxidation does not occur for PtSi on B or P-doped polysilicon, or for As concentrations of 1×1020 cm−3 or less.
Sb-Doped Polycrystalline Si Obtained by Means of Sb and Si Thin-Film Reactions
Authors: Gong S. F. , Robertsson A. E. , Hörnström S.-E. , Radnoczi G. , Hentzell H. T. G. 
Published: March 2011

ABSTRACTWe have grown Sb-doped poly-Si by thin-film reactions between Sb and amorphous Si (a-Si). The reactions and microstructures of the films were investigated by transmission electron microscopy (TEM) during in situ annealing and Auger electron spectroscopy (AES). The reactions either resulted in an amorphous Sb-Si (a-Sb-Si) alloy or caused crystallization of a-Si at low temperatures, depending on the film thickness of the a-Si layer as well as the heating rate. The electrical properties of the as-deposited and the annealed thin multi-layers deposited on SiO2 layer were determined using Hall measurements. After annealing at 1375 K for 60 minutes, Sb-doped poly-Si with a resistivity of 1.4×10−2 ohm-cm was obtained. A p-n junction was formed in a p-type Si substrate by using an a-Si/Sb/a-Si multi-layer as a diffusion source. The doping concentration in the Si substrate was obtained using secondary ion mass spectrometry (SIMS).
Investigation of Impurity Neutralization and Defect Passivation in Polycrystalline Silicon Solar Cells
Authors: Kazmerski Lawrence L. 
Published: March 2011

ABSTRACTThe passivation of grain boundaries and the neutralization of impurities in polycrystalline silicon, important processes for the improvement of performance of devices fabricated from this material, are discussed. The incorporation of hydrogen into grain boundaries is investigated using surface analysis methods. Volume-mapping techniques are used to identify the bonding mechanisms of the hydrogen in oxygen-free and oxygen-rich intergrain regions. Interactions between shallow acceptors (B, Al, Ga and In) and hydrogen in polycrystalline Si are studied. The bonding mechanisms involved in the acceptor neutralization process at the grain boundaries are evaluated using microanalytical techniques. Differences in the incorporation of molecular and atomic hydrogen, and corresponding variation in electrical passivation of grain boundaries, are observed. Volume-indexed AES and Auger difference spectroscopy data are complemented by scanning tunneling microscope images to confirm the direct hydrogen-silicon bonding in boron-doped grain boundaries.
The Polysilicon-Silicon Interface
Authors: Keyes Robert W. 
Published: March 2011

ABSTRACTPolycrystalline silicon is frequently deposited on single crystal silicon as a part of devices. The poly is used as both a dopant source and a low resistance contact in a modern method of fabricating high gain bipolar transistors. The randomness of polysilicon and its interface with the single crystal is an inherent source of differences among nominally identical transistors, however, and is a marked departure from the trend towards more and more perfect crystals that characterizes the rest of silicon technology.
Microstructures of Polysilicon
Authors: Sinclair R. , Carim A. H. , Morgiel J. , Bravman J. C. 
Published: March 2011

ABSTRACTSome typical microstructural studies of polycrystalline silicon using transmission electron microscopy (TEM) are described, including the application of this material for assisting TEM investigations themselves. Examples include oxidation and realignment of polysilicon thin films, the structure of polysilicon in EEPROM devices, polysilicon in trench capacitors and measurement of SiO2 layer thicknesses with polysilicon overlayers. It is also shown tha grain growth in heavily phosphorus doped polysilicon films can be followed by in situ heating in the TEM.
Characteristics of Arsenic Doped Polycrystalline Silicon-Gate Capacitors After Rapid Thermal Processing
Authors: Angelucci R. , Wong C. Y. , Sun J. Y.-C. , Scilla G. , McFarland P. A. , Megdanis A. C. , Landi E. 
Published: March 2011

ABSTRACTThe feasibility and advantages of using rapid thermal annealing to achieve a proper n+ polysilicon work function are demonstrated. Our data shows that RTA can be used to activate arsenic in the polysilicon gate after a regular furnace anneal or to diffuse and activate arsenic without any prior furnace anneal. Interface states and fixed charges due to RTA can be annealed out at 500°C for 30 min in forming gas. New insights into the diffusion, segregation, and activation of As in polysilicon during furnace and/or rapid thermal annealing have been obtained.
Grain Boundary States in Float-Zone-Si-Bicrystals
Authors: Petermann G. , Haasen P. 
Published: March 2011

ABSTRACTA near Σ25 grain boundary has been studied electrically in FZ-silicon at various degrees of n-doping. The boundary is electrically active without previous heat treatment. A unique density-of-states can be derived from dc and ac measurements at all dopings and temperatures investigated. The model of the charged g.b. includes potential fluctuations in the g.b. plane. Admittance spectroscopy allows to differentiate between g.b. states and deep centers its the compensating space charge zone.
Nitrogen Contamination in Simox Wafer
Authors: Davis G. E. , Jones K. S. , Prussin S. 
Published: March 2011

AbstractNitrogen was found in as-implanted SIMOX wafers. The redistribution of the nitrogen within the SIMOX structure was studied after the formation anneal for different temperatures (up to 1250 °C), times, ambients (nitrogen plus 1% oxygen and argon), and anneal with and without a capping layer. The nitrogen was found to be concentrated in the buried SiO2 layer and the adjacent damaged silicon regions in the as-implanted oxygen wafers. During the formation anneal, the nitrogen was found to collect(build-up) at the Si/SiO2 buried layer interface. It is postulated that an oxynitride is preferentially formed at the interface where the dangling silicon bonds can capture the soluble nitrogen.
Melting and Solidification Dynamics in Zone Melting of Si Films.
Authors: Dutartre D. 
Published: March 2011

AbstractWe discuss the physics involved in the melting and solidification of Silicon On Insulator thin films (SOI) using lamp or graphite strip heaters. The melting front, called “explosive melting”, controls to a large part the final morphological quality of the SOI film. It exhibits instabilities which can (i) nucleate the dewetting of the film, (ii) cause voids, and (iii) produce a poor surface morphology. The morphologies of the solidification fronts are analyzed. We show that, depending on the experimental conditions, different physical mechanisms are responsible for the front breakdown. Thus we propose that the variety of front morphologies results from the variety of the mechanisms involved, and of their combinations with the “faceting effects”.
Zone-Melting Recrystallization of Silicon on Alumina
Authors: Letavic T. J. , Maby E. W. , Gutmann R. J. 
Published: March 2011

AbstractPolysilicon-on-alumina films have been zone-melt recrystallized with a graphite strip heater. High levels of in-plane stress and stress concentrations due to alumina grain pull-outs cause tensile failure at high temperature. This can be avoided by phosphorus incorporation into an SiOo layer between the polysilicon film and the alumina substrate. The glass layer provides high-temperature viscoelastic strain relief and planarizes the alumina substrate. Double-crystal diffractometry and anisotropic etch techniques indicate that the recrystallized silicon-on-alumina film texture is (100).
TEM and SEM Studies of Multiple Silicon on Insulator Films for Three Dimensional Circuits.
Authors: Williams D.A. , McMahon R.A. , Ahmed H. , Barfoot K.M. , Godfrey D.J. , Dunne B. , Mathewson A. 
Published: March 2011

AbstractMultiple layers of silicon on insulator have been recrystallized using a dual electron beam technique. The aim of the investigations was to produce structures suitable for three dimensional circuit applications, and so a number of strategies have been used, providing a range of opportunities for such applications. In particular, two layers of silicon on insulator have been recrystallized simultaneously, and also a second layer has been recrystallized, seeded from a previously regrown film.
Hot Electron Transistors Using Si/CoSi2
Authors: Levi A. F. J. , Tung R. T. , Batstone J. L. , Anzlowar M. 
Published: March 2011

AbstractWe have explored the possibility of fabricating a metal base transistor in the Si/CoSi2 material system. Utilizing recent advances in the growth of thin, pinhole free, CoSi2 layers on Si(111) we have measured the transistor characteristics of a Si/CoSi2/Si structure. The observed low common emitter current gain is attributed to an absence of current carrying states in the CoSi2 transistor base.
Buried Layer Tungsten Deposits In Porous Silicon: Metal Penetration Depth and Film Purity Determinants
Authors: Blewer Robert S. , Tsao Sylvia S. , Gutierrez Gina M. 
Published: March 2011

AbstractInfiltration of anodically prepared porous silicon with tungsten hexafluoride gas has been investigated as a function of silicon porosity, source gas pressure and carrier gas type and flow rate. The depth of tungsten metallization in the silicon has been shown to depend most sensitively on the WF, partial pressure, and less on the flow rate and carrier gas type. Penetration depths of 30 pirn have been attained. Structural integrity of the tungsten layer is dependent on the porosity of the starting material and the degree of internal oxidation of the porous silicon surface area.
Materials and Processes For Silicon TFT's On Aluminosilicate Glass: An Alternative Soi Technology
Authors: Troxell John R. , Harrington Marie I. , Erskine James C. , Dumbaugh William H. , Fehlner Francis P. , Miller Roger A. 
Published: March 2011

AbstractAs-deposited polycrystalline silicon and argon ion laser recrystallized silicon thin film transistors (TFT's) have been fabricated on Corning Code 1729 glass substrates. This novel aluminosilicate glass has an expansion coefficient matched to that of silicon and a chemical durability comparable to that of fused silica. N-channel enhancement mode transistors were made using conventional IC device fabrication procedures (including thermal oxidation to form the gate insulator) modified to have a maximum processing temperature of 800 C. The- polycrystalline silicon TFT's exhibit leakage currents of less than 2x10-11 A/ μm; of channel width and good stability and reproducibility. Transistors made in the recrystallized silicon show field effect electron mobilities as high as 270 cm2/V s, approximately 15 times the mobility of comparable devices made in as-deposited polycrystalline silicon. The recrystallized silicon devices also exhibit lower threshold voltages and lower leakage currents than do the comparable polycrystalline silicon devices. Major advantages of this TFT technology include the use of a novel, potentially low cost glass substrate and the simultaneous processing of both polycrystalline and recrystallized silicon devices on the same substrate material. This approach represents a new avenue for the incorporation of active devices into a variety of applications including integrated active matrix displays.
Thin (100 nm) SOS for Application to Beyond VLSI Microelectronics
Authors: Reedy Ronald E. , Garcia Graham A. 
Published: March 2011

AbstractOf the numerous requirements for advanced VLSI silicon microelectronics, power dissipation per unit area, speed, packing density and radiation hardness are especially important. Power dissipation and speed have forced an evolutionary path from PMOS to NMOS to NMOS E/D and to the currently used CMOS. As evidenced by the large number of publications, CMOS on an insulating substrate is receiving increased attention due to its potential as the next generation in MOS evolution. We review results of our previous and current research in silicon on sapphire (SOS) which has led to high quality ultrathin SOS (<100 nm thick) appropriate for high density CMOS circuitry. Basic materials developments, device performance, and CMOS design considerations in 100 nm thick improved SOS will be discussed.
Formation of Double Layered SOI With Controlled Crystal Orientation
Authors: Miyajima Toshiaki , Tsuji Hideyuki , Maekawa Masashi , Koba Masayoshi 
Published: March 2011

AbstractFor the crystal orientation control of multi-layered SOI (Silicon on Insulator) by the laser recrystallization technology, the shape and size of seeds were investigated. By utilizing dot seeds less than 3μm square instead of a line seed, the crystal orientation control of a SOI layer was successfully realized without causing evaporation of silicon. Moreover, the dot seed method enabled us to control the crystal orientation of multi-layered SOI by virtue of small heat flow through seed regions.In the mean time, it was proved that the SOI crystal orientation gradually rotated as the crystal propagated away from the seeds and that the degree of rotation in the second SOI layer was smaller than that in the first one.
Elimination of Defects in Laser-Recrystallized SOI by Stress Relief
Authors: Martinez Andre , Pandya Ranjana , Arnold Emil 
Published: March 2011

AbstractWe report the application of a stress-relief technique aimed at reducing the density of dislocations and subgrain boundaries in laser-recrystallized Silicon-On-Insulator (SOI) material. By providing alternate mechanisms for relieving the stresses responsible for defect generation in the Si film, it is possible to exercise a large degree of control over the subgrain boundary density. Large areas of SOI material completely free of dislocations and subgrain boundaries have been obtained by inserting a low-viscosity layer under the silicon film and using an appropriately shaped cw laser beam as the heat source. During the process of zone-melt recrystallization this layer softens and provides an alternative stress relief mechanism, thus reducing the mechanical constraint on the growing crystal. Several examples of subgrain boundary control are described, which have resulted in crystalline regions in excess of 300 μm by several millimeters completely free of low-angle grain boundaries and dislocations.
Laser Recrystallized SOM for Strain Gauge Applications
Authors: Kunshan Xing , Xuemin Xu , Chenglu Lin , Songsheng Tan , Shihchang Tsou 
Published: March 2011

AbstractA novel material SOM (Silicon on Metal) was obtained by laser recrystallization. 0.5miti amorphous-Si film was deposited by glow discharge on a metal substrate covered with lym CVD Si02 Boron ions were implanted in a-Si at an energy of 60KeV and a dose of 5xl015cm-2. A CW argon laser was used to recrystal-lize a-Si film. After CW argon laser irradiation, a-Si was recrystallized and the grain size was increased to 10x40ym, the concentration profile of impurities became uniform and the electrical properties of SOM were improved significantly, sheet resistance lower than 60Ω/⃞n was obtained. The gauge factor of recrystallized SOM materials measured by a cantilever transducer was higher than 30. The devices made of this material have pressure sensitivity of 6mV/V for pressure range 1 bar.
Formation of Buried Nitride Layers in (110) Silicon
Authors: Datye Abhaya K. , Kaushik Vidya S. , Kendall Don L. , Martinez-Tovar Bernardo , Myers David R. 
Published: March 2011

AbstractHigh fluence ion implantation of N (1x1018/cm2 at 150 keV) has been used to form buried nitride layers in (110) silicon. After annealing at 1200 C for 5 hrs. a continuous, polycrystalline alpha-Si,N- layer (200 nm thick) is observed beneath a surface silicon film 306 nm thick. The upper Si/Si3N4 interface appears to be more abrupt than that observed in (100) silicon with minimal dendritic intergrowth and no evidence for microtwinning in the silicon. Furthermore, a band of nitride precipitates can be detected 500 nm below the continuous nitride layer. These nitride precipitates grow semi-coherently within the silicon with no observable strain or misfit dislocations within the silicon. The nitride precipitates are internally faulted to accomodate the 10% lattice mismatch in the (0001) nitride direction. Short term anneals reveal that the precipitates have fully crystallized within 10 min. at 1200 C while the continuous nitride layer is still amorphous.
Total Dielectric Isolation (TDI) of Device Islands Using SIMOX/SOI Technology
Authors: Hemment P L F , Robinson A K , Reeson K J , Davis J R , Kilner J R , Chater R J , Stoemenos J 
Published: March 2011

AbstractA method of achieving total dielectric isolation (TDI) of device islands (or larger areas) using ion beam synthesis to form a continuous but non planar layer of SiO2is described. The technique involves implantation through a patterned masking layer in which windows have been opened to define the dimensions and location of the islands. TDI structures have been successfully formed in annealed (1300°C, 5 hours) wafers implanted with a dose of 2.2 x 1018O+cm2at 200 keV, using a thermal oxide mask of thickness 4750 Å.
Pyridine N-Oxides As Polymeric Nonlinear Optical Materials
Authors: Griffin Anselm C. , Bhatti Amjad M. , Howell Greg A. 
Published: March 2011

ABSTRACTThree polymers containing pyridine N-oxide imine pendant moieties were prepared and examined. Although the appropriate low molar mass model compound is liquid crystalline, the polymers are not mesogenic. Two of them form fibers and clear, transparent glasses. Side reactions involving the N-oxide group during polymerization are postulated as leading to the lack of mesomorphism in these materials although the π-chromophore remains essentially intact for the bulk of the material as judged by UV-Vis and other spectral data. They may have NLO application as poled polymeric glasses.
Nonlinear Optical Response of Excitons Confined to one Dimension
Authors: Greene B. I. , Orenstein J. , Thakur M. , Rapkine D. H. 
Published: March 2011

ABSTRACTWe present femtosecond time-resolved transient absorption data taken on polydiacetylene-pTS single crystals over the entire wavelength region of exciton resonance. Observed optical changes are accounted for by a model which predicts quantitatively the large resonant and nonresonant optical nonlinearities.
Quasiparticle Excitations in Polyenes and Polyacetylene
Authors: Tavan Paul , Schulten Klaus 
Published: March 2011

ABSTRACTWe apply the Pariser-Parr-Pople Hamiltonian to study many-electron excitations in polyenes and polyacetylene. The excited singlet states of polyenes, calculated by a multireference double excitation expansion, are classified as quasi-particle excitations, namely as triplet-triplet magnons and particle-hole excitons. From finite polyene spectra we derive approximate dispersion relations for these quasi-particles in the infinite polyene, i.e. polyacetylene.
Quadratic and Cubic Nonlinearities in Solution of Intramolecular Charge Transfer Aromatic Molecules A Quantum Two-Level Approach
Authors: Barzoukas M. , Fremaux P. , Josse D. , Kajzar F. , Zyss J. 
Published: March 2011

ABSTRACTA two-level expression of the second-order hyperpolarizability (y) is proposed, and shown to contain a negative charge transfer (CT) contribution. Frequency dispersed measurements of the quadratic and cubic susceptibility of N-(4-nitropheny1)-L-prolinol (NPP), N-(4-nitrophenyl)-N-methylaminoacetonitrile (NPAN) and 2-(N-prolinol)-5-nitropyridine (PNP) are reported. The electric field induced second-harmonic generation (EFISH) and third-harmonic generation (THG) techniques in solution are used. A two-level model dispersion of y as from THG measurements is shown to lead to a neglegible electronic contribution to the overall EFISH nonlinearity, as compared to the orientational contribution. The theoretical β-components of these molecules, obtained consistently by finite-field and perturbational approaches, clearly confirm that the β-tensor is one-dimensional along the donor-acceptor CT axis. The off resonance quadratic polarizabilities (β) of these molecules are sequenced as follows : β(NPP)> β(PNP)> β(NPAN). However this increased efficiency is obtained at the expense of the transparency range.
Semiconductor-Doped Polymers. Linear and Nonlinear Optical Properties.
Authors: Wang Y. , Suna A. , Mahler W. 
Published: March 2011

ABSTRACTSemiconductor clusters with sizes of a few to hundreds of Å, covering the entire range from molecular to bulk, have been prepared within polymer films. For PbS, the band-gap shifts to higher energy as the cluster size decreases and eventually converges to the transition energy of the first excited state of PbS molecule. The observed dependence of band-gap on cluster size can be explained by a tightbinding model that takes into account the effects of band nonparabolicity. These semiconductor-doped polymers represent a new class of nonlinear optical materials. Here we present the nonlinear optical properties of polymer films doped with 50 A CdS and discuss the possible mechanisms.