bluuebunny/crossref_metadata_2025_split huggingface dataset:
Dopant Enhanced Grain Growth During Crystallization of Amorphous Silicon Using Rapid Thermal Anealing
Authors: Kakkad R. , Fonash S. J. , Howell P. R. 
Published: March 2011

AbstractPECVD a-Si deposited at 250ºC on 7059 glass was used as precursor material to produce low resistivity large grain doped poly Si. The films doped in the range of 1020−1021 cm-3 with P during growth or by ion implantation wereannealed at 700ºC for times 2 to 5 minutes using RTA. A dopant enhanced grain growth was observed with grain sizes of the order of 3 μm for films of only 2000Å thickness. Resistivity as low as 6x10-4 Ω-cm and mobility as highas 34 cm2 /V-sec. were obtained using this low thermal budget process.These values are comparable to those obtained in the literature using significantly higher annealing temperatures.
Nanosecond Thermal Processing of Polysilicon thin Films
Authors: McCarthy A. M. , Weiner K. H. , Sigmon Tom. W. 
Published: March 2011

AbstractSignificant improvement in properties of polysilicon thin films for VLSI applications was achieved using nanosecond thermal processing causing laser-induced melting followed byrecrystallization. Sheet resistance was reduced by as much as a factor of five on polysilicon thin films and underlying oxide integrity was not detectably disturbed.
Origin of Grain Boundary Recombination Activity in Silicon Wafers
Authors: Amanrich H. , Martinuzzi S. , Pasquinelli M. 
Published: March 2011

AbstractIn silicon bicrystals grain boundaries (GBs) become recombining after they have been annealed in argon at temperatures higher than 800°C for tens of hours. In order to verify the eventual influence of metallic elements, interstitials gold atoms are introduced in the bicrystals by diffusion (T ≤ 8000 C) from gold dots deposited far from the GB (gold could be segregated by the GB but cannot give deep levels in the grains). It is found by DLTS, EBIC contrast and LBIC scan map that the recombination strength of GBs is not changed by gold in diffusion in as grown bicrystals, while it is reduced in annealed samples. Similar results are obtained with GBs of polycrystalline wafers.It is concluded that the activation of GBs in CZ silicon bicrystals is certainly due to the segregation of a slow diffuser like oxygen, and that fast diffusers play a secondary role only.
Effects of the Grain Size on the Electrical Properties of Boron-Doped Polysilicon Films
Authors: Kobayashi A. , Baba S. , Kinbara A. , Akimori H. , Kawaji M. , Owada N. 
Published: March 2011

AbstractThe electrical properties have been investigated on boron-doped polycrystalline silicon films with the average grain size of 50 nm and of 370 nm. It is shown that Hall mobility is strongly dependent on the grain size, and the temperature dependence is changed by hydrogenplasma treatment (HPT).After the treatment in the larger grain film, the mobility of about 40 cm2/V sec is obtained and it shows the boron acceptor level of 0.043 eV, which is almost the same as that of the level in monocrystalline silicon. A kink in the mobility vs temperature curve which is observed in the smaller grain film disappears by HPT.These phenomena will be discussed in relation to the density of the trapping states at the grain boundary of the films.
Polysilicon Integration
Authors: Ellul J. , Calder I.D. 
Published: March 2011

AbstractPolycrystalline silicon has found numerous applications in silicon integrated circuits, initially as a MOS gate material, and later for advanced isolation, capacitor electrodes, resistors, interconnect, bipolar emitters and bases, trench refill, doping sources, and the active material in thin film transistors. Integration of these techniques in a BiCMOS technology requires knowledge of the interactions between the processing steps, and their cumulative effect on the final device and circuit operation. New process techniques also present opportunities for process simplification, added functionality, or improved performance. Examples of polysilicon applications that interact with other process steps and influence device performance are P+ and N+ poly gates and silicidation of gate poly. Silicidation improves circuit speed and provides additional integration opportunities in the form of faster local interconnect, but it may create a problem for older designs with synchronous timing circuitry. More innovative integration of polysilicon includes improved deposition techniques, such as the use of amorphous silicon, “Lo-Hi” poly, in sinat doping, and deposition from disilane sources enable more flexible process design. Other innovations include polysilicon emitters, bases, and buried sinkers in bipolar design, polysilicon sidewall spacers in CMOS, and polysilicon based active transistors for display applications and three dimensional integration.
Influence of Polysilicon Processing on the Quality of Thin RTP/Furnace Gate Oxides
Authors: Haase J. , Ferretti R. , Prasad S. 
Published: March 2011

AbstractThin layers of oxides (10–11nm) were fabricated by rapid thermal (RTP) or furnace oxidation. The RTP oxides were grown at different temperatures and were exposed to a two step post oxidation anneal (POA). The furnace oxides were grown at one temperature and received different POA/s. As gate metallization, in-situ phosphorus-doped polysilicon was used. Post poly anneal (PPA) is carried out in the RTP system using a set of temperatures. After having defined MOS structures by photolithography oxide charges, breakdown voltages and breakdown charges were determined. For different current densities, FN-voltage shift during constant current injection was monitored to make lifetime predictions. Received data were correlated to the different process parameters.
High Performance Thin Film Transistors for Scanner Applications
Authors: Hseih B.-C. , Hawkins G.A. , Ashok S. 
Published: March 2011

AbstractWe report on the characteristics of polycrystalline silicon (polysilicon) thin film transistors (TFTs) fabricated with low temperature crystallized LPCVD amorphous silicon film as an active layer and plasma enhanced chemical vapor deposition (PECVD) SiO2 as a gate insulator. High performance transistor characteristics are achieved, even though no process temperature exceeds 600°C. No threshold drift has been observed. As a result, these devices are highly suitable for application to image scanners as well as flat panel displays.
Cmos Polysilicon Thin Film Transistors with Simultaneously Deposited Layers for Source-Drain and Gate
Authors: Huang T. Y. , Tsai C. C. , Wu I. W. , Lewis A. G. , Chiang A. , Bruce R. H. 
Published: March 2011

AbstractA new process architecture for fabricating CMOS thin film transistors (TFTs) using in-situ-doped polysilicon source-drain layers is proposed. In the new architecture, a top-gate n-channel TFT and a bottom-gate p-channel TFT, or vice versa, form a CMOS pair. This allows an n+ - doped polysilicon bottom (or top) layer to serve simultaneously as the source-drain layer of the n-channel TFTs and the gate layer of the p-channel TFTs; while a p+ - doped polysilicon top (or bottom) layer serves as the source-drain layer of the p-channel TFT and the gate layer of the n-channel TFT. It thus eliminates the deposition of a separate doped gate layer normally required in the conventional process flow. In addition, a thin tri-layer stack, consisting of undoped-poly / gate dielectric / undoped-poly, separates the two doped polysilicon layers, thus allowing the use of a single island mask to define the channel regions for both the n- and p-channel TFTs. As a result, the photolithographic steps are also reduced by one mask. Working n- and p-channel TFTs with both top- and bottomgate structures, obtained by reversing the dopant types of the top and the bottom layers, have been successfully demonstrated using low-temperature (< 600 °C) polysilicon technology.
Geometrical Effects and Disintegration of Narrow TiSi2/Poly-Si Lines
Authors: Norström H. , Maex K. , Vandenabeele P. 
Published: March 2011

AbstractThe geometrical shape and the thermal stability of the TiSi2/poly-Si interface on narrow lines has been studied. The examined line-widths varied between 0.8 μm and 1.5 μm. The thermal stability was found to strongly correlate to theactual line-width of the structures. At the onset of degradation, at and above 900 ºC, narrow lines were observed to disintegrate at a much faster rate than wider ones. Cross-sectional microscopy (TEM and SEM) revealed the TiSi2/poly-Si interface to be curved inwards. The interface bowing was found to be more pronounced on narrow lines. It is suggested that the interface bowing results from a mechanical pinning of the TiSi2/poly-Si interface by the side-wall spacers.
Interface Oxide Free Poly Silicon Deposition Using in-Situ HF Cleaning Process
Authors: Huang C.K. , Feygenson A. 
Published: March 2011

AbstractA LPCVD polysilicon deposition with in-situ anhydrous HF cleaning process has been developed. The deposited polysilicon and interface properties have been characterized using SIMS, XTEM, RBS, and Auger analysis. The results indicate that an interface oxide free polysilicon deposition using conventional LPCVD furnace can be achieved by careful design of in-situ anhydrous HF cleaning process. After short time rapid thermal annealing, random and channel RBS studies show that most of the deposited polysilicon is epitaxially aligned with silicon substrate and there is no oxide ball up phenomenon. Twinning structure was observed under TEM. No impurity segregation at the poly-mono silicon interface confirms that the interface is oxide free. Possible applications of this polysilicon process include polysilicon emitter contact for high speed bipolar technology and source/drain contacts for MOS devices.
From Point Defects to Amorphous Structures: Atomic Resolution Studies of Semiconductor Surfaces by Scanning Tunneling Microscopy (STM)
Authors: Wiesendanger R. , Tarrach G. , Buergler D. , Scandella L. , Guentherodt H.-J. 
Published: March 2011

AbstractWe have studied point defects, linear defects as well as spatial transitions between ordered and disordered structures on silicon surfaces with atomic resolution by using scanning tunneling microscopy (STM). Point defects in the vicinity of multiple step edges as well as surface reconstructions at multiple step edges as high as 3 nm have been characterized by STM. STM images of partially disordered silicon surfaces prepared by laser and thermal annealing demonstrate the potential of STM for characterizing non-periodic surfaces on the atomic scale.
Electron Microscopy of Interfaces in Silicon Carbide Whisker-Reinforced Alumina Composites
Authors: Alexander K. B. , Angelini P. , Becher P. F. 
Published: March 2011

AbstractKnowledge about the nature of interfaces between SiC whiskers and alumina matrices is critical to understanding the mechanical behavior of these types of composites. The fracture toughness, in particular, is strongly influenced by the bond characteristics of this interface. Previous results have shown that oxidizing the whiskers in air prior to composite fabrication by vacuum hot-pressing results in composites which have lower toughness compared to those made with whiskers in the as-received condition. This investigation focusses on the effects of oxidizing and reducing surface treatments on the whiskers themselves and on the whisker-matrix interface. High resolution electron microscopy (HREM) was used to characterize the morphology and the amount of amorphous phase at the whisker-matrix interface, as well as the crystallography and topography of the interface. The present results indicate that the characteristics of the whisker/matrix interface may not be directly related to the initial whisker surface chemistry. Surprisingly, the thickest thermally-grown oxide layer resulted in the thinnest amorphous film at the SiC/Al2O3 interface.
Surface Structures and Rearrangements in Oxides
Authors: Mccartney M. R. , Smith David J. 
Published: March 2011

AbstractElectron-beam-induced surface reactions and rearrangements have been observed for a number of oxides including MgO, TiO2, SrTiO3 and SnO2 using conventional and ultra-high-vacuum high-resolution electron microscopes. Electron irradiation of TiO2 resulted in a variety of effects including reduction, re-oxidation and amorphization. SnO2 was observed to form facets readily during high-resolution imaging but it was stable against reduction except when exposed to extreme current densities which caused the formation of metallic tin crystals. Electron irradiation of MgO under UHV conditions resulted in the formation of facetted pits. The surfaces of SrTiO3 were stable for moderate electron dose rates but rapidly amorphized when irradiated at extreme current densities.
Defects and Metal Particles in Zeolites Studied with High Resolution Electron Microscopy
Authors: Zandbergen H. W. , van Dyck D. 
Published: March 2011

AbstractA number of examples of high resolution electron microscopy on defects and metal particles in zeolites is given: defects in Zeolite Y and Zeolite β, metal particles in ZSM-5, and structural changes due to reactions in Zeolite L and Zeolite Y.
Atomic Structure of Ag/Ni Interfaces
Authors: Gao Y. , Merkle K. L. 
Published: March 2011

AbstractWhile in heterophase systems of small lattice parameter differences, misfit dislocations are often formed at the interface, it is not known, whether and in which form, misfit localization occurs when the misfit is very large. The atomic structure of Ag/Ni interfaces (misfit 14%) was studied by high-resolution electron microscopy (HREM). A special technique was developed to prepare interface specimens suitable for HREM observations.Lattice statics calculations, using embedded-atom potentials, were performed to determine the structure and energies of Ag/Ni interfaces. The lowest interfacial energy was found for the cube-on-cube orientation and (111) interfaces. This is in agreement with the experimental observation, that all interfaces are strongly faceted with (111)Ag/(111)Ni facets.Misfit localization was found by HREM and computer simulation. The HREM observations will be compared to images derived from image simulations, based on model structures obtained from embedded atom calculations.
Applications of Strained Layer Superlattices
Authors: Smith D. L. , Laurich B. K. , Mailhiot C. 
Published: March 2011

ABSTRACTBecause of different band-edge lineups, strain conditions, and growth orientations, various strained-layer superlattice (SLS) materials can exhibit qualitatively new physical behavior in their optical properties. We describe two examples of new physical behavior in SLS: strain-generated electric fields in polar growth axis superlattices and strained type II superlattices. In SLS, large electric fields can be generated by the piezoelectric effect. The fields are largest for SLS with a [111] growth axis; they vanish for SLS with a [100] growth axis. The strain-generated electric fields strongly modify the optical properties of the superlattice. Photogenerated electron-hole pairs screen the fields leading to a large nonlinear optical response. Application of an external electric field leads to a large linear electrooptical response. The absorption edge can be either red or blue shifted. Optical studies of [100], [111], and [211] oriented GaInAs/GaAs superlattices confirm the existence of the strain-generated electric fields. Small band-gap semiconductors are useful for making intrinsic long wavelength infrared detectors. Arbitrarily small band gaps can be reached in the type II superlattice InAs/GaSb. However, for band gaps less than 0.1 eV, the layer thicknesses are large and the overlap of electron and hole wavefunctions are small. Thus, the absorption coefficient is too small for useful infrared (IR) detection. Including In in the GaSb introduces strain in the InAs/GaInSb superlattice, which shifts the band edges so that small band gaps can be reached in thin-layer superlattices. Good absorption at long IR wavelengths is thus achieved.
Role of Interface-States in the Reverse Bias Aging of GaAs Schottky Barriers
Authors: Christianson K. A. 
Published: March 2011

ABSTRACTForward bias capacitance has been used to examine the Au/W/GaAs and Au/Pt/Ti/GaAs Schottky barriers present in power microwave MESFET devices to see if interface-state generation plays any role in the previously reported reverse bias barrier height aging process. If a constant carrier capture cross-section is assumed, forward bias capacitance has shown that for samples strongly susceptible to aging (i.e. the Au/W/GaAs samples in this study) interface-state generation is taking place during the aging process. The validity of the constant capture cross section assumption has been tested by examining the I–V properties. For those samples whose reverse I–V properties were not dominated by thermionic-field emission, similar increases in interface-state densities were evaluated from the I–V characteristics for the degraded samples.
Thermal Stability of A1-Pt Thin Films/GaAs for Self-Aligning Gate Contacts
Authors: Wilk G. D. , Blanpain B. , Olowolafe J. O. , Mayer J. W. , Zheng L. R. 
Published: March 2011

ABSTRACTSeveral compositions of A1-Pt thin films have been co-evaporated on GaAs substrates to study the stability of the alloys at high-temperature anneals. The A1 concentration in the alloys ranges from 45 at.% to 70 at.%, and we show that the films meet thermal stability requirements imposed by GaAs selfaligning gate technology for compositions between AIPt and Al2Pt.
Electronic Stimulation of Acceptor Reactivation IN p - Type Hydrogenated GaAs
Authors: Szafranek I. , Stillman G. E. 
Published: March 2011

ABSTRACTThe mechanism of light-induced reactivation (LIR) of shallow substitutional acceptors in high-purity p-type hydrogenated GaAs has been investigated. Photoluminescence was used to determine the dependence of the rate and extent of this effect on photon energy, illumination intensity, as well as on sample temperature and chemical composition. At a sample temperature of 1.7 K a sharp threshold in the photon energy, Et, has been observed at about 7.5 meV below the bandgap energy of GaAs. This energy corresponds approximately to the onset of acceptorbound exciton absorption in the material. For photon energy E < Et, only a weak reactivation effect is observed. The efficiency of reactivation increases dramatically for E > Et, and for sufficiently large values of (light intensity).(illumination time) product the LIR process saturates. Both the extent of the subthreshold effect and the saturation level that is attainable with E > Et are independent of the photon energy, excitation power and exposure time in the investigated range of these quantities. For E > Et the initial LIR rate depends on the square of the light intensity, indicating a bimolecular reaction in terms of the photo-generated carrier densities. The observed strong dependence of the saturation level on the sample temperature during LIR is found to be consistent with the relative binding energies of different acceptor-hydrogen passivating complexes in GaAs. Based on these results, it is proposed that LIR of acceptors is electronically stimulated via recombination-enhanced vibrational excitation of acceptor-hydrogen complexes.
A Study of the Phase Decomposition of Fe-Ni-Al-Mo Alloys
Authors: Miller M.K. , Hetherington M.G. , Weertman J.R. , Calderon H.A. 
Published: March 2011

AbstractThe aging of β′ NiAl precipitates in ferritic Fe-Ni-Al alloys has been studied by transmission electron microscopy (TEM) and atom-probe field-ion microscopy (APFIM). The addition of Mo alters the lattice parameter of the phases and segregation of Mo to the interface between the matrix and the particles may alter the interfacial energy. The compositions of the matrix, precipitates and interfaces have been measured by TEM and APFIM. The results are compared.
Mechanical Properties and Microstructure of Certain Niaico(Hf) Alloys
Authors: Russell S. M. , Law C. C , Lin L. S. , Levan G. W. 
Published: March 2011

AbstractCobalt-modified NiAl alloys are being studied for their potential for room temperature ductility and toughness. An alloy of Ni - 29.3 a/o Al - 36.7 a/o Co has shown improved toughness and ductility with respect to binary NiAl alloys due in part to a stress-induced martensitic transformation. Furthermore, the cobalt additions have altered the slip behavior to {110}<111> type from {110} <001> for binary NiAl alloys. Hafnium was added to improve the alloy's relatively poor creep resistance and high temperature strength. Hf was found to be insoluble in the NiAlCo alloy and formed precipitates with a hexagonal structure. The Hfmodified alloy had improved high temperature strength. In addition, the Hf apparently changed the creep mechanism resulting in poorer creep resistance at low temperatures, but improved creep resistance at higher stresses and temperatures.
Deformation and Dislocation Structure of Ti3AI Single Crystals
Authors: Minonishi Y. 
Published: March 2011

AbstractDeformation characteristics of Ti3A1 single crystals has been examined as a function of orientation and temperature. This paper mainly describes the result of compression along the c axis. In this orientation, the yield stress increases from 300 to 1100K, decreasing rapidly thereafter. The slip system activated are {1121}<1126> and dislocations observed are nearly of edge character. The anomaly is discussed in comparison with the behavior of other intermetallics and pure metals. An important role this pyramidal slip plays in polycrystalline ductility of Ti3Al is shown in the light of the briefly described results of the prism slip.
Alloy Design of Ordered Intermetallics
Authors: George E. P. , Liu C. T. 
Published: March 2011

AbstractOrdered intermetallics based on aluminides and silicides constitute a unique class of metallic materials possessing promising high-temperature properties. However, brittle fracture and poor ductility have limited their use as engineering materials in most cases. During the past ten years extensive research has been conducted on ordered intermetallics. As a result, significant progress has been made in identifying various causes of brittle fracture, and their relative importance in different ordered alloys. In some cases this understanding has helped achieve dramatic improvements in ductility. We review here three different classes of brittle fracture in ordered intermetallics and discuss the results in terms of model alloy systems chosen from each class. Ni3A1 and NiAl are discussed as prototypical ordered alloys prone to intrinsic intergranular brittleness. They are used to review our current understanding of intrinsically weak grain boundaries and the mechanisms by which boron is thought to suppress intergranular fracture. Next, FeAl and Fe3A1 are discussed as examples of ordered intermetallics that are susceptible to environmental embrittlement at ambient temperatures. Recent discoveries in these two alloy systems are reviewed with special emphasis on some of the rather interesting but subtle effects of test environment. Finally, A13X type intermetallics (A13Sc, Al3Ti-base, and Al3Zr-base alloys) are discussed as examples of ordered alloys that have high symmetry (L12structure), are relatively soft, yet cleave transgranularly with very little ductility. In all these cases, experimental results are compared with theoretical calculations.