bluuebunny/crossref_metadata_2025 huggingface dataset:
Biomimetic Processing of Ceramics and Ceramic-Metal Composites
Authors: Yasrebi M. , Kim G. H. , Gunnison K. E. , Milius D. L. , Sarikaya M. , Aksay I. A.
Published: March 2011

Biomimetic design and processing of laminated B4C-Al cermets, based on knowledge gained from the microstructure-property characterization of abalone shells, is described. In the nacre section of the shell, the microstructure is highly organized as CaCO3(aragonite) crystals, with a thickness of 0.25 μm, separated by a layer of organic matter 300–500 Å thick. This organization forms a miniature “brick and mortar” microstructure. The resultant strength and fracture toughness of the nacre, i.e., 180 MPa and 7 MPa-m1/2, are many orders of magnitude higher than those of monolithic CaCO3. The processing of laminated B4C-Al cermets, based on the microstructure of the nacre, was performed by a combination of tape casting of the ceramic and infiltration of the metal. The resultant cermets displayed a 40% increase in both fracture toughness and strength over monolithic B4C-Al cermets.
Intercalation Chemistry: a Novel Approach To Materials Design
Authors: Giannelis E.P. , Mehrotra V. , Russell M.W.
Published: March 2011

Intercalation of layered solids is used as a means to manipulate a variety of molecular and polymeric species into well-ordered multilayer films with an architecture controllable at the molecular level. Dielectric, conductivity and optical measurements demonstrate the potential of developing new families of materials with new functionalities by exploiting the synergistic effect of guest/host interactions.
Ion-Implantation Effects on Spin-on-Glass (Sol-Gel) SiO2 Films
Authors: Shacham-Diamand Y. , Moriya N. , Kalish R.
Published: March 2011

Silicon and phosphorus ions were implanted into Spin-On-Glass (Sol-Gel) SiO2 films and were found to modify the material properties. Two SOG types, polysiloxane andsilicate, were ion-implanted with doses in the 5 × 1014 − 1.65 × 1016cm−2range and energies of 40keV - 190keV. The implanted SOG on silicon samples were characterized by ellipsometry, infra-red spectroscopy, etching and capacitance measurement of aluminum/SOG/silicon devices. The results indicate that the polysiloxane type SOG shrinks due to the implant and its effective refractive index increases. The ion-implant of the polysiloxane SOG also changed its structure and composition as seen by the variations of the infra-red transmission spectrum, etching characteristics, and dielectric constant. Silicate SOG exhibits less shrinkage due to the implant but its other characteristics show dependence on the dose similar to that of the polysiloxane SOG.
Tailored Molecular Precursors of Yttrium Oxide Using Functional Alcohols and Acetylacetone as Modifiers
Authors: Hubert-Pfalzgraf Liliane G. , Poncelet Olivier , Daran Jean-Claude
Published: March 2011

Yttrium is involved as oxide in a variety of advanced materials. Hydrolysis of its most common alkoxide, yttrium oxoisopropoxide Y5O(OiPr)13 , is difficult to control as a result of the high electropositivity of the metal. Functional alcohols such as 2-methoxyethanol and acetylacetone have thus been used as modifiers. These tailored precursors have been fully characterized (single crystal X-Ray diffraction, IR, NMR. ). The tendency of methoxyethanol to act as a bridging ligand and to stabilize high oligomers - Y(OC2H4OMe)3 is a decamer - gives some insight into its behavior as “network builder”. The unexpected cleavage of acetylacetone offers a route to an interesting acetatoacetylacetonate derivative, Y2(OAc)2(acac)4(H2O)2 , but also suggest that this classical “modifier” could be affected by the hydrolysis-polycondensation reactions of the metallic species during the sol-gel process. Comparison of the hydrolysis behavior of the different precursors was performed.
Synthesis and Structural Characteristics of Polycerams
Authors: Boulton J.M. , Fox H.H. , Neilson G.F. , Uhlmann D.R.
Published: March 2011

Sol-gel techniques are readily applicable to the preparation of Polycerams. These hybrid materials uniquely combine organic and inorganic functionalities at the molecular level. Polycerams have here been prepared from tetraethoxysilane and modified, functionalized polybutadiene, polyethylene oxide urethane and polyethyleneimine. The structures and physical characteristics of the materials are here in reported.
Mixed Carbides via Polymer Route
Authors: Soraru Gian D. , Babonneau Florence , Mackenzie John D.
Published: March 2011

Several polymetallocarbosilanes, pre-ceramics precursors for Si-M-C-O systems, have been prepared from polycarbosilane and metallic alkoxides, M(OR)n with M = Ti, Zr and Al. Polymers have essentially been characterized by Magic Angle Spinning Nuclear Magnetic Resonance (MAS-NMR). The pyrolysis process has been followed for each system with X-Ray Diffraction (XRD) and MAS-NMR. The role of the metallic element M on the transformation process of these systems will be discussed.
DC Plasma Synthesis of Aluminum Nitride Ceramic Powders
Authors: Lu Z. P. , Pfender E.
Published: March 2011

A novel Triple DC Torch Plasma Reactor (TTPR) has been developed for the plasma synthesis of fine ceramic powders. The reactor consists of three identical plasma torches. The plasma jets from these torches form a converging plasma volume into which the starting powder is fed. Thermodynamic equilibrium calculations have been performed for predicting the behavior of an aluminum-nitrogen system. Aluminum nitride has been synthesized by using the TTPR operating in the non-transferred mode. Product characterizations indicate that single hexagonal phase AIN ceramic powder has been obtained.
Fabrication of Superconducting Bi-Sr-Ca-Cu-O Oxide Films Using the Metal Alkoxide Method
Authors: Katayama Shingo , Sekine Masahiro
Published: March 2011

Superconducting films in the Bi-Sr-Ca-Cu-O system were fabricated using metal alkoxides. To make a mixed alkoxide solution into a dip-coating solution, insoluble Cu alkoxide was modified with 2-dimethylaminoethanol and insoluble Bi alkoxide was dissolved in the presence of Ca and/or Sr alkoxides. The structures of these alkoxide derivatives were studied by FT-IR, 1 H-NMR, and EXAFS. The film with Tc(zero)=115K was fabricated using the alkoxide solution with a nominal composition of Bi:Sr:Ca:Cu=2:2:3:4.
Superconducting Yba2Cu3O7−X Fibers Fabricated by the Sol-Gel Method Using Metal Alkoxides
Authors: Katayama Shingo , Sekine Masahiro
Published: March 2011

Superconducting YBa2Cu3O7−x fibers were fabricated by the sol-gel method using modified metal alkoxides. To prepare precursors of a homogenous and viscous sol, Y and Cu alkoxides were modified with ethyl acetoacetate(EAA) and ethylenediamine(en), respectively. Their structures were determined by FT-IR and EXAFS. The sol prepared from modified alkoxides was spun into gel fibers by the spinning apparatus. They were subsequently fired to obtain superconducting fibers.
Sol-Gel Processing of the Ti2Ca1Ba2Cu2O8+X High Tc Superconducting Phase
Authors: Teepe M. R. , Kenzer D. S. , Moore G. A. , Kordas G.
Published: March 2011

An alkoxide Sol-Gel system was developed to produce bulk powders of the TI2Ca1Ba2Cu2O8+x high Tc superconducting phase. Methoxyethoxide and Cu(II) ethoxide precursors were used for the formation of homogeneous sols. Solubility of the Cu(II) ethoxide was aided by using a 2-methoxyethanol/methyl ethyl ketone/toluene solvent system. The sols were characterized by small angle x-ray scattering (SAXS) and TEM. Powders were produced by rotary evaporation followed by thermal treatment in a closed container with thallium metal present at 900°C for various calcination times. Powders were characterized by x-ray diffraction, resistivity and magnetic susceptibility measurements, and chemical analysis. Samples exhibited transition onsets between 100 and 110K depending upon the processing conditions.
Preparation of Superconducting YBa2Cu3O7−x Compounds By Water Extraction Variant Of Sol-Gel Process
Authors: Deptula A. , Lada W. , Olczak T. , zoltowski T. , Di Bartolomeo A.
Published: March 2011

The starting sols were prepared by addition of ammonium hydroxide to acidic solutions of Y-Ba-Cu acetates or by dissolving solid Ba9CO9 or CuCO9.CuCOH)2H2O in acetates of the remaining components. The sols were then gelled to spherical particles with diameter below 50μm by extracting water with 2-ethyl-l-hexanol or to shard by evaporation of water. After thermal treatment of both powders amorphous and then crystalline YBa2Cu,9O7−x were obtained. Formation of these compounds is strongly improved by aging the gel at 200°C. Green and sintered pellets exhibit excellent superconductivity properties.
Preparation, Thermal Processing Behavior And Characterization Of Powdered And Bulk Yba2Cu3O7−x From Freeze Dried Nitrate Solutions.
Authors: Coppa N. , Bura A. , Schwegler J. W. , Salomon R. E. , Myer G. H. , Crow J. E.
Published: March 2011

Solutions of Y, Ba and Cu nitrate were spray-frozen. Very small particles consisting of atomic mixtures of these salts remained after the water was sublimed. These YBCO precursors were characterized and their behavior was studied in detail while they were thermally decomposed by a variety of techniques. Kilogram size batches are routine. The final YBCO products were obtained as powders and sintered bars. Sintered materials exhibited excellent phase purity (>99%) and super-conducting characteristics (Tc = 92 K), while powdered materials had secondary phases present. Some of these samples having high percentages of second phases exhibited sudden drops in resistivity to a few micro-ohms at 200 or 240 K followed by a zero resistance transition at 92 K. Coincident with this drop in resistance was a discontinuity in the magnetization.
Aryl-Bridged Polysilsesquioxanes - New Microporous Materials.
Authors: Shea Kenneth J. , Webster Owen , Loy Douglas A.
Published: March 2011

The first representatives of a new family of microporous, aryl-bridged polysilsesquioxanes have been prepared by sol-gel processing of bis-1,4-(triethoxysilyl)benzene la, bis-4,4′- (triethoxysilyl)biphenyl 2a, bis-4,4′-(triethoxysilyl)terphenyl 3a, and bis-9,10-triethoxysilyl anthracene 4a. The bis(trichlorosilyl) analogs of la and 2a (lb and 2b, respectively) were also examined. The materials produced by hydrolysis and condensation of the monomers provide an opportunity to fully condense to a network with rigid-rod organic spacers interspaced at regular intervals in the silicate-like framework. The xerogels produced upon subsesquent processing of the gels have extremely high surface areas (256–1100 m2/g; BET) with porosities confined to the micropore domain (< 200 nm). Solid state (CP MAS) 13C and 29Si NMR were used to evaluate the extent of hydrolysis and degree of condensation in the xerogels. The porosity and thermal stability of the aryl bridged polysilsesquioxanes may lead to applications as chromatographic absorbents. The transparent materials may also have optical applications arising from both the gels′ high refractive indices and the covalent incorporation of ultraviolet chromophores.
Non-Linear Organic Dyes In Polyceram Hosts
Authors: Boulton J.M. , Thompson J. , Fox H.H. , Gorodisher I. , Teowee G. , Calvert P.D. , Uhlmann D.R.
Published: March 2011

Non-linear organic dyes, such as 2-methy1–4-nitroaniline (MNA) and p-nitroaniline (pNA), have been incorporated in Polyceram monoliths and thick films prepared by the hydrolysis and co-condensation of tetraethoxysilane and trimethoxysilylpropyl substituted polyethyleneimine. Strong second harmonic generation was observed.
Crystallization of Silicon Ion Implanted LPCVD Amorphous Silicon Films for High Performance Poly-TFT
Authors: Wu I-W. , Chiang A. , Fuse M. , Öveqoglut L. , Huang T. Y.
Published: March 2011

The mechanism of silicon ion implantation on the crystallization kinetics and the resulting grain sizes of LPCVD α-Si films have been studied by x-ray diffraction and transmission electron microscopy. The solid-phase crystallization was proceeded by random nucleation and growth from the Si/SiO2 interface. The most effective grain size enhancement was found by targeting the peak concentration of implanted siliconbeyond the Si/SiO2 interface, such that the maximum kinetic energy transfer occurred at that interface. The average grain size increases from ∼0.16 μm to ∼2.0 μm by a Si + implantation at 92KeV and a dose of 2X1015 cm-2 for 0.1 μm silicon film. X-ray diffraction intensities were analyzed to optimize implanting dose, beam current and energy for different film thickness. Grain size enhancement was achieved by retarding the random nucleation and increasing the nucleation activation barrier from ∼3.9eV to ∼4.9 eV for the implanted sample. The amorphous to crystalline growth activation barrier of ∼3.2 eV was not altered by Si+ implantation. The observed nucleation and growth kinetics change may be due to the chemical effect of the recoiled oxygen atoms from the substrate. The field-effect mobilities for both n- and p-channel TFTs increase by a factor of two with deep silicon implant.
Diffusion of as and B in Polysilicon/ Single Crystal Silicon Systems
Authors: Park K. , Batra S. , Banerjee S. , Lux G. , Manukonda R.
Published: March 2011

Comparative studies of As and B diffusion in polysilicon-on-single-crystal Si systems have been performed by Cross-sectional Transmission Electron Microscopy (XTEM) and Secondary Ion Mass Spectrometry (SIMS). Arsenic and BF2 implanted in 300 nm Low Pressure Chemical Vapor Deposition (LPCVD) polysilicon are diffused into the underlying Si substrate by Rapid Thermal Annealing (RTA) or furnace annealing. Diffusion profiles of Asappear to be continuous across the poly/single crystal Si interface except for a peak at the interface and show a gradual increase towards the interface within the polysilicon layer due to an inhomogeneous distribution of grain sizes in Asimplanted polysilicon layers. On the other hand, indiffusion of B gives a discontinuous doping profile at the interface due to accumulation of B-defect complexes created by dissolution of defectclusters in polysilicon. At low anneal temperatures, the B profiles in single crystal Siare shallower than the As profiles. This is because most of the B in polysilicon films is immobile during annealing near the peak region where the solid solubility limit is exceeded, and because of low B segregation at grain boundaries, thereby reducing the impactof grain boundaries in terms of high diffusivity. At high anneal temperatures, the native oxide at the interface breaks up and causes the polysilicon layer to align epitaxiallywith respect to the underlying substrate. Time to breakup of interfacial oxide depends on dopant species and anneal temperatures. Oxide breakup takes longer for As-doped samples than for B-doped samples. For high thermal budget anneals, B diffusion into the substrate is greater than As diffusion because of higher B diffusivities in single crystal Si.
Comparison of Amorphous and Polycrystalline Silicon Films as a Solid Diffusion Source for Advanced VLSI Processes
Authors: Park K. , Batra S. , Banerjee S. , Lux G.
Published: March 2011

This paper discusses the diffusion behavior of P, B and As from as-deposited amorphous/ polycrystalline silicon into the underlying Si substrate as a function of RTA/ furnace annealing conditions. The evolution of grain microstructure has been studied in as-deposited amorphous/ polycrystalline silicon to determine the inter-dependency of diffusion behavior and grain microstructure. After 60 s RTA at 1100° C for P doping, the microstructure of asdeposited amorphous silicon is drastically changed by rapid grain growth, whereas it is only slightly changed for asdeposited polysilicon. This leads to formation of deeper junctions for as-deposited polysilicon than for as-deposited amorphous Si. For B doping, there is little difference in the final microstructure between as-deposited polysilicon and as-deposited amorphous silicon after anneal. For low annealing temperatures, the junctions for both amorphous and polysilicon diffusion sources are laterally uniform in spite of local inhomogeneities due to grain boundaries. This is believed to be due to the rapid lateral spread of dopants along the interface prior to indiffusion into the substrate. At high annealing temperatures, a number of dark fringes are observed in the substrate along the interface from Crosssectional Transmission Electron Microscopy (XTEM) micrographs, which are more conspicuous for as-deposited amorphous Si. We believe that these fringes arise from local doping inhomogeneities or lattice strain in the substrate. For 30 s RTA at 1150° C, the native interfacial oxide appears to break up, causing epitaxial alignment of the polysilicon layer with respect to the underlying substrate.
Low Stress Silicon Nitride and Polysilicon Films for Micromachining Applications
Authors: Beck P. A. , Taylor S. M. , Mcvittie J. P. , Ahn S. T.
Published: March 2011

Reduced stress silicon nitride and undoped, as deposited, polysilicon films have been characterized on a variety of silicon based substrates within the confines of co-fabrication compatibility of micromechanical structures with VLSI processing. Average stress and stress uniformity through the films are shown to vary with substrate parameters.
Rapid Thermal Chemical Vapor Deposition of Polycrystalline Silicon From Dichlorosilane
Authors: Kermani Ahmad , Johnsgard Kristian E. , Suthar Sailish , Kim Ki-Bum , Lam Chung
Published: March 2011

Rapid Thermal Chemical Vapor Deposition (RTCVD) of undoped and insitu doped polycrystalline silicon films has been accomplished in a cold-wall reactor. Dichlorosilane was used for the silicon source and AsH3 gas was used as the dopant source. Thedeposition kinetics of poly-silicon films on silicon dioxide over a range of deposition temperatures, pressures and carrier gas chemistries was studied. Both blanket and selective deposition modes were examined. The poly-silicon films were examined by scanning electron microscopy (SEM) and transmission electron microscopy (TEM) for morphology and grain size analysis. Using X-ray diffraction technique, preferred grain orientation dependency of poly-silicon films on growth conditions was investigated. Dopant incorporation, dopant activation and oxygen content of polysilicon films were measured by secondary ion mass spectrometry (SIMS), four point probe, and spreading resistance profiling (SRP) techniques.

This paper is to report the results of material characterization of polysilicon films deposited by RTCVD, and to address the applications and advantages of ‘Integrated Processing’ technology involving deposition of polysilicon.
Polycrystalline Silicon as a Mechanical Material
Authors: Muller Richard S.
Published: March 2011

In 1982, Kurt Petersen published “Silicon as a Mechanical Material” in the Proceedings of the IEEE. This thorough review article heightened focus on the advantages of utilizing the mechanical as well as electrical properties of single-crystal silicon. Processes for shaping single-crystal silicon based upon selective etching were shown in the article to make silicon useful for a variety of miniature mechanical devices.
Impact of Polycrystalline Silicon Processing on Properties of MOS Memory Devices
Authors: Queirolo G. , Brambilla M. , Mavero C.
Published: March 2011

In EEPROMs mèmory devices, tunnel oxides with high fluence, and interpoly oxides with low conductivity and high breakdown field are needed. Tunnel oxide fluence is degraded by high temperature annealing after the polysilicon deposition, while interpoly oxide is degraded by low temperature oxidation, particularly on rough films. As a consequence, a process optimization, giving a good compromise between these two quantities is required. In this work we shown that if a flat polysilicon is used, an interpoly oxide of good quality can be obtained at low temperature, maintaining a high value for the tunnel oxide fluence.
Investigations of an Antimony Doped Poly-Silicon Gate Structure for P-Type JFET Applications
Authors: SÖDERBÄrg Anders , Grelsson Ö. , Magnusson U.
Published: March 2011

A polysilicon gate structure for application as gate material in p-channel JFET's is presented. The structure was manufactured using solid-phase epitaxy of an evaporated antimony/amorphous—silicon layer. The fabrication process together with experimental evaluation of both diode and JFET characteristics is given. The structure shows near ideal n+p-junction behaviour and the fabricated JFET's are normally off with good values of subthreshold swing and transconductance.
Effect of the MOS Process on the Work-Function Difference Between the Polysilicon Gates and the Silicon Substrate
Authors: Lifshitz N.
Published: March 2011

Polysilicon gates are an important element of modem MOS integrated circuit technology. The workfunction difference (ϕps) between the polysilicon gate and the silicon substrate is a vital parameter of the MOS system because it determines the threshold voltage of the field-effect transistor. Ideally, ϕps is determined by the doping level in both polysilicon and the substrate. In reality process variations influence the ϕPS in a tangible way. Some of these effects are reviewed in the present paper.
Post-Annealing Effect on the Reliability of Ultra-Thin Silicon Dioxide with Polysilicon Gate
Authors: Yoneda Kenji , Fukuzaki Yoshiki , Satoh Kazuo , Todokoro Yoshjhiro , Inoue Morio
Published: March 2011

Time dependent dielectric breakdown (TDDB) characteristics and TEM observation of ultra-thin silicon dioxide with the polysilicon gate after post-annealing and oxidation at 1000-1100 °C are discussed. The high temperature post-annealing decreases the TDDB characteristics of ultra-thin oxide with polysilicon gate. The charge to breakdown is reduced drastically with increasing the annealing temperature and annealing time. The dielectric breakdown reliability degradation of ultra-thin tunneling oxide by the post-annealing can be explained as the partial oxide thinning and electric field concentration due to the increase of roughness at the polysilicon gate/ultra-thin tunneling oxide interface. This increase of roughness is due to the grain growth of polysilicon gate and viscous flow of oxide, which are enhanced with increasing the annealing temperature and time.
Comparative Studies of Gate Oxides Using Thermal, Stacked Gate, and Rapid Thermal Oxidation
Authors: Chittipeddi S. , Roy P. K. , Kannan V. C. , Singh R. , Dziuba C. M.
Published: March 2011

In this paper we report on the quality of gate oxides obtained using three different oxidation techniques, namely thermal oxidation, rapid thermal oxidation and stacked gate oxidation. We report on the oxide thicknesses, the flatband voltage, threshold voltage, and QSS/Q values for MOS capacitors fabricated using these three techniques. We also fabricated MOSFET's using thermal oxides and stacked gate oxides, and find that the stacked gate oxides have a lower gate oxide defect density. Lattice images have also been obtained for the Si/SiO2 interface using transmission electron microscopy (TEM). We find that stacked oxide synthesis results in lower stresses and asperities at the interface relative to thermal and rapid thermal oxidation.
Large-Grain Polysloon Films Depied by Raped Thermal IPCVD
Authors: Mitdhell S.J.N. , McNeill D.W. , Raza S.H. , Armstrong B.M. , Gemble H.S.
Published: March 2011

Rapid thermal LMVD has been applied to the deposition of polysiliccn layers. The single process wafer sits in an air—cooled quartz chamber, and is heated by tungsten—halcgen lamps. A nicrowave cavity upstrean of the hot zone may be used to introduce a remote plasma.

Pblysilicon films have been deposited on ocidized suhstrates in the temperature range 590C–860C, and at pressures between 0.lmber and 10mbar. Conditions for the reduction of carbon and oxygen levels down to 5x1017 cm are presented.

An in—situ CF4 plasma clean prior to polysiliccn deposition is shown to dramatically affect grain—size. At 720C and Imbar, plasma-cleaned polysilicon has a grain—size of 35Chm, whereas non—cleaned polysilicon has a grain—size of only 120nm. The CF4 schedule leaves a clean ocide surface with fewer nucleation sites, resulting in larger grains.

Both types of polysilicon were used in the fabrication of TMT'S. Devices with larger grain material pass 10 times as much current as those with smaller grains, show a channel nobility of >20cm v s, and have a threshold voltage of 5V. Thus, direct deposition of polysilicon layers on a plasma—cleaned substrate is an attractive alternative to crystallization from amorphous silicon, for TFT's.
Characterization and Modeling of Polysilicon TFTs and TFT-CMOS Circuits for Integrated Driver Applications
Authors: Kim Dae M. , Qian Feng , Esralian Michael J. , Whitlow Dana E. , Culter Robert G. , Thayer Stephen C.
Published: March 2011

Polysilicon TFTs and TFT-CMOS circuits are characterized. Circuit elements examined comprise subcircuits pertinent to integrated drivers suitable for flat panel display applications. Performance features of multistage static row drivers are also presented. Additionally, AC measurement of TFTs was performed in order to extract device parameters. The channel mobility measured in a time of flight environment is presented and discussed.
Crystal Growth Study of Silicon and Germanium Wafers Used for Photovoltaic Devices
Authors: Chibani A. , Sof S. , Hamoud M. , Gauthier R. , Pinard P.
Published: March 2011

To develop the EPR material quality, electrical and structural charact erizations were executed by EBIC, LBIC, TEM, ECP and X diffraction. Two interface types were observed; some interfaces parallel and constitued by Σ3 and Σ9 twins, show low electrical activity; other are curved with no defined index and higher electrical activity. Some orientations such as (111),(220),(331) appear more frequently.
The Effect of Amorphous Silicon Layer in PE-CVD Titanium Polycide Gate Dielectrics
Authors: Chen Shih-Chang , Sakamoto Akihiro , Tamura Hiroyuki , Yoshimaru Masaki , Ino Masayoshi
Published: March 2011

Titanium silicide (TiSix), used as polycide gate consists of TiSi1.1 and amorphous silicon (a—Si), was deposited by Plasma Enhanced Chemical Vapor Deposition method (PE—CVD). The effect of a—Si layer in PE—CVD Ti polycide gate dielectrics has been studied. In order to evaluate the a—Si layer effect, three types of samples were prepared on gate SiO2 film with following structures: a) a—Si / TiSil.1 / a—Si / phosphorus (P) doped poly—Si, b) a—Si / TiSi1.1 / non—doped poly—Si / P doped poly—Si and c) a—Si / TiSi1.1 / P doped poly—Si, respectively. Furthermore, in order to avoid the influence of native oxide existence at the interface, the pre—cleaning treatment was performed in—situ on the poly—Si film surface before TiSi1.1 film deposition. The gate dielectric strengths of these samples indicate that the gate dielectric degradation in PE—CVD Ti polycide gate is greatly dependent on Si under layer crystallization. It is effective using a—Si film as the under layer in decreasing the gate dielectric degradation. This is due to the Ti oxide interlayer, formed at the interface of TiSi2.0 and poly—Si films, whichrestrains the TiSix local penetration.
High Resolution Electron Microscopy of Defects in High-Dose Oxygen Implanted Silicon-On-Insulator Material
Authors: Visitserngtrakul S. , Jung C. O. , Cordts B. F. , Roitman P. , Krause S. J.
Published: March 2011

High resolution electron microscopy (HREM) has been used to study the atomic arrangement of defects formed during high-dose oxygen implantation of silicon-on-insulator material. The effect of implantation parameters of wafer temperature, dose, and current density were investigated. Wafer temperature had the largest effect on the type and character of the defects. Above the buried oxide layer in the top silicon layer, HREM revealed that microtwins and stacking faults were created during implantation from 350–450°C. From 450–550°C, stacking faults were longer and microtwinning was reduced. From 550–700°C, a new type of defect was observed which had lengths of 40 to 140 nm and consisted of several discontinuous stacking faults which were randomly spaced and separated by two to eight atomic layers. We have referred to them as “multiply faulted defects” (MFDs). Beneath the buried oxide layer in the substrate region, the defects observed included stacking faults and ( 113 ) defects. The results indicated that some parts of the ( 1131 defects can assume a cubic diamond structure created through a twin operation across (115) planes. Details of the structure and formation mechanisms of MFDs and other defects will be discussed.
Hrem Investigation on the Interface Between a Monocrystalline Substrate and a Doped Polysilicon Layer
Authors: Paul-Henri Albarede
Published: March 2011

Arsenic doped polysilicon was deposited on a <001> oriented Si wafer. Cross-section TEM specimen preparation was performed, giving the vertical structure of the stack. The observation was done with a <110> zone axis to ensure that the interface is strictly oriented under the electron beam. High resolution imaging on the very interfacial region proved the existence of an ultrathin regular amorphous layer running along the interface (thickness 1 rim). Complementary analytical investigations showed that the layer was really amorphous (EELS) and that the dopant was overconcentrated in this layer (EDXS linescan and SIMS profile). Therefore, a slight amorphization of the interface added to an abnormal migration of the dopant gives a well detectable layer separating both crystalline phases.
New Relaxation Mechanism in Short Period Si/Ge Strained-Layer Superlattices
Authors: Wegscheider Werner , Eberl Karl , Abstreiter Gerhard , Cerva Hans , Oppolzer Helmut
Published: March 2011

High quality Si/Ge strained-layer superlattices composed of a sequence of alternating 3 monolayers pure Si and 9 monolayers pure Ge have been grown by molecular beam epitaxy at 310°C on Ge(001) substrates. In order to investigate the transition from coherent to incoherent growth in these tensily strained structures a set of samples with varying number of superlattice periods has been studied by transmission electron microscopy. It is found that superlattices as thick as 33 nm at least show perfect and defect-free layer growth whereas for thicker superlattices strain accommodation occurs. For this strained heteroepitaxial system we observed, to our knowledge, for the first time the formation of microtwins as the only relaxation mechanism. High-resolution lattice imaging reveals that the twin lamellae result from successive glide of 90° (a/6)<112> Shockley partial dislocations on adjacent {111} planes from the surface towards the bulk. The activation barrier which has to be overcome in the case of 90° partial dislocations is compared with the energies required for the nucleation of 60° perfect and 30° partial misfit dislocation half-loops.
HREM of Defects in GaAs/Ga1-xInxAs Strained Layer Superlatuices
Authors: Unal O. , Laurich B. K. , Mitchell T. E.
Published: March 2011

GaAs/Gal-xInxAs strained layer superlattices with well-widths of 7nm, barrier widths of 14nm and periods of 10 to 30 have been examined by HREM both in plan view and cross section. Strain release occurs mostly by dislocation generation but twins are also observed, especially at the substrate interface. High resolution images of dislocations, twins and interfaces are analyzed to elucidate mechanisms of strain release.
Electron Microscopy of Ordering Related Defects in Alloys.
Authors: Broddin D. , Leroux C. , Tendeloo G. Van
Published: March 2011

Recent results are presented which indicate that the core structure of anti-phase boundaries is sensitive to changes in temperature and alloy composition. Isolated anti-phase boundaries in CoPt3 are found to undergo a structural change when the order-disorder transition temperature is approached from below. Periodic anti-phase boundaries of the long period structures in Cu3Pd, Au3Zn and Au3Cu exhibit similar phenomena. Detailed results on the core structure of periodic boundaries in alloys annealed close to the order-disorder transition are compared to the results of a Monte Carlo analysis for finite temperatures of (100) anti-phase boundaries in L12 alloys.
Nanostructure Evolution During Processing of Thin-Film Gels: A High-Resolution Electron Microscopic Study. 2. The Thin-Film Gel Derived From Pb(Zr0.45Ti0.55)O2(OR)2
Authors: Kang C. , Dey S. K. , Eyring L.
Published: March 2011

High-resolution electron microscopic examination of alkoxide thin-film gels has been employed to study the drying and aging of thin-film Pb(Zr0.45Ti0.55)O2(OR)2as it evolves from the gel to the ferroelectric perovskite product. The initially amorphous film is observed to aggregate to form ordered islands with inter-metal distances close to that of the final structure embedded in a highly disordered matrix. When these aggregates are at the surface they grow and decompose more rapidly to the perovskite product. The progress to a polycrystalline final state is followed and recorded in real time and in time-lapse at high resolution.
Annealing of Alpha-Recoil Damage in Natural Titanite, CaTiSiO5.
Authors: Eby Ray K. , Ewing Rodney C.
Published: March 2011

Isothermal and isochronal annealing of alpha-recoil damage was performed on the mineral titanite, CaTiSiO5. Crushed-grain samples were heated for 21 hrs, at 100°C intervals from 300°-700°C. HRTEM imaging of alpha-recoil collision cascades (amorphized regions), after each temperature interval, showed that there was no change in the abundance or appearance of the cascades at 300°C, but an apparent decrease in cascade size occurs at 400°C (from 3.8 nm to 2.4 nm diameter). A decrease in the size of collision cascades may indicate repair of interstitial defects at cascade boundaries (where interstitials dominate), while the cascade cores remain amorphous (cores acquire more extensive knock-on damage). At 500°C, the number of collision cascades observed decreases by greater than 90%, indicating major annealing of the amorphous cascade cores, and precipitates appear on titanite grain surfaces. At 600°C, changes do not occur. At 700°C, both the cascades and precipitates are absent; the alpha-recoil damage is fully annealed.
Dynamic TEM Observation on Oxide Glass Materials
Authors: Iijima Sumio
Published: March 2011

Intensity fluctuation in high resolution electron microscope (HREM) images of amorphous Tl-Ba-Ca-Cu-O oxide films is observed. The fluctuation with a frequency of few tens of Hertz and an amplitude of about 0.3nm, occurs under an intense electron beam irradiation. It is shown experimentally that atom migration in the films is responsible for the fluctuations. The result is also supported by computer image simulations on a model structure for amorphous film.
Structures of Nb/Al2O3 Interfaces Produced by Different Experimental Routes
Authors: Mayer J. , Mader W. , Knauss D. , Ernst F. , Rühle M.
Published: March 2011

Nb/Al2O3 interfaces were produced by (i) diffusion bonding of single crystalline Nb and Al2O3 at 1973 K, (ii) internal oxidation of a Nb-3at.% Al alloy at 1773 K, and (iii) molecular beam epitaxy (MBE) growth of 500 nm thick Nb overlayers on sapphire substrates at 1123 K. Cross-sectional specimens were prepared and studied by conventional (CTEM) and high resolution transmission electron microscopy (HREM). The orientation relationships between Nb and Al2O3 were identified by diffraction studies. HREM investigations revealed the structures of the different interfaces including the presence of misfit dislocations at or near the interface. The results for the different interfaces are compared.
Motion of Crystal/Crystal and Crystal/Amorphous Interfaces
Authors: Batstone J. L.
Published: March 2011

Motion of ordered twin/matrix interfaces in films of silicon on sapphire occurs during high temperature annealing. This process is shown to be thermally activated and is analogous to grain boundary motion. Motion of amorphous/crystalline interfaces occurs during recrystallization of CoSi2 and NiSi2 from the amorphous phase. In-situ transmission electron microscopy has revealed details of the growth kinetics and interfacial roughness.
A Study on the Mechanism for the Influence of High Density of Defect Movement on the Leakage Current of PN Junction
Authors: Tonghe Zhang , Shenghui Zhou , Yuguang Wu , Yan Luo
Published: March 2011

The results in the paper show that high defect density appears during rapid thermal annealing. The spreading of the defect distribution increases with increasing of the annealing time. So the leakage current increases up. It is found that the PN junction leakage current for short annealing time(5s) and for hot implantation are obviously lower than that of RT implantation. The mechanism of the leakage current reduction is discussed.
Device-Degradation in III-V Semiconductor Lasers and Led's—Influence of Defects on the Degradation—
Authors: Ueda O.
Published: March 2011

Material issues in III-V alloy semiconductors and our current understanding of degradation in III-V semiconductor lasers and LED's are systematically reviewed.

Generation of defects and thermal instability are among these issues for these systems. Defects introduced during crystal growth are classified into two types: interface defects and bulk defects. Defects belonging to the former type are stacking faults, V-shaped dislocations, dislocation clusters, microtwins, inclusions, and misfit dislocations, and the latter group includes precipitates and dislocation loops. Defects in the substrate can also be propagated into the epi-layer. Structural imperfections due to thermal instability are also found. They ame quasi-periodic modulated structures due to spinodal decomposition of the crystal either at the liquid/solid interface or growth surface, and atomic ordering which also occurs on the growth surface through migration and reconstruction of the deposited atoms.

Three major degradation modes, rapid degradation, gradual degradation, and catastrophic failure, are discussed. For rapid degradation, recombination-enhanced dislocation climb and glide are responsible for degradation. Differences in the ease with which these phenomena occur in different hetero-structures are presented. Based on the results, dominant parameters involved in the phenomena are discussed. Gradual degradation takes place presumably due to recombination enhanced point defect reaction in GaAlAs/GaAs-based optical devices. This mode is also enhanced by the internal stress due to lattice mismatch. However, we do not observe this mode in InGaAsP/InP-based optical devices. Catastrophic failure is found to be due to catastrophic optical damage at a mirror or at a defect in GaAlAs/GaAs DH lasers, but not in InGaAsP/InP DH lasers. In each degradation mode, the role of defects in the degradation and methods of elimination of degradation are discussed.
Macroscopic Stress and Device Reliability of 1.3μm and 1.5μm Wavelength GaInAsP Channeled Substrate Buried Heterostructure Lasers
Authors: Swaminathan V. , Koszi L. A. , Focht M. W.
Published: March 2011

The macroscopic stress of 1.3μm and 1.5μm wavelength GaInAsP-InP channeled substrate buried heterostructure lasers is related with device reliability. The radius of curvature, R, of the device is taken as a measure of its macroscopic stress and the change in dc threshold current, ΔIth, after an accelerated aging test is taken as a measure of device reliability, with high ΔIth, indicating decreased reliability. R or ΔIth was changed by altering the p-side contact width or the p-side Au bonding pad thickness. No correlation was found between R and ΔIth. For example, changing the p-contact width from 6 to 125μm resulted in a reduction of ΔIth by a factor of 2 – 10 among the wafers studied. However, the change in the active layer stress, as determined by R−1, was at most only 25%. Similarly, increasing the Au bonding pad thickness from 0.6 to 9.0μm increased the active layer stress by a factor of 2, but with little change in Alt. It is concluded that the macroscopic stress does not affect device reliability for the GaInAsP lasers.
Influence of Point Defects on GaAs Devices
Authors: Look David C.
Published: March 2011

From electron-irriadiation studies, it is known that point defects can strongly affect the electrical properties of GaAs-based MESFET's, MODFET's, solar cells, resonant-tunneling diodes, MIMIC circuits and other devices. As an example, 1 × 1016 cm−2, 1 MeV electrons reduce the transconductance in a 1 μm by 200 μm MESFET by nearly an order of magnitude. Fortunately, annealing at 350 °C for 10 min. can largely restore the device performance, although not without some adverse effects. Point defects, or simple point defect complexes, can also exist in as-grown GaAs and affect devices in several different ways. For example, an As-rich stoichiometry can lead to an abundance of Ga vacancies, and thus to a higher Si donor activation in implanted MESFET devices; however, it can also promote an increase in unwanted impurities which sit on the Ga site. As another example, extremely high (> 3 × 1019 cm−3 ) concentrations of As arntisites, which are found in MBE GaAs grown at 200°C, lead to very unusual electrical and optical properties, and make possible a highly useful buffer material anid a very fast photoconductive switch. However, there are also adverse effects here, such as slow-transients in some MODFET devices, which may result from defect diffusion. Thus, the effects of point defects in GaAs devices must be understood.
Requirements of Electrical Contacts to Photovoltaic Solar Cells
Authors: Gessert T. A. , Coutts T. J.
Published: March 2011

The importance of contacts to photovoltaic solar cells is often underrated mainly because the required values of specific contact resistance and metal resistivity are often thought to be relatively modest compared with those associated with very large scale integration (VLSI) applications. However, due to the adverse environmental conditions experienced by solar cells, and since many of the more efficient cells are economically advantageous only when operated under solar concentration, the requirements for solar cell contacts are sometimes more severe. For example, at one-sun operation, the upper limit in specific contact resistance is usually taken to be 10−2 Ω-cm2. However, at several hundred suns, this value should be reduced to less than 10−4 Ω-cm2. Additionally, since grid line fabrication often relies on economical plating processes, porosity and contamination issues can be expected to cause reliability and stability problems once the device is fabricated. It is shown that, in practice, these metal resistivity issues can be much more important than issues relating to specific contact resistance and that the problem is similar to that of providing stable, low resistance interconnects in VLSI. This paper is concerned with the design and fabrication of collector grids on the front of the solar cells and, although the discussion is fairly general, it will center on the particular material indium phosphide. This III-V material is currently of great importance for space application because of its resistance to the damaging radiation experienced in space.
On the Origin of Multiple Peaks in the Deep Level Admittance Spectroscopy of Dx Centers in AlGaAs:Sn
Authors: Chakravarty S. , Subramanian S. , Arora B. M.
Published: March 2011

Deep level admittance spectroscopy (DLAS) of the Sn-DX centers in Alx Ga1−x As:Sn (0.2 < x < 0.6) shows three peaks SNi, SN2 and SN3. The SN3 peak is identified to be related to the dominant peak of the Sn-DX center observed in the conventional DLTS technique. The SN1 and SN2 peaks are not easily seen in DLTS. A careful analysis of the DLAS data shows that the three peaks are not due to independent (chemically distinct) defects related to Sn, but they are caused by the multiple sates of the same DX center.
Radiation Enhanced Dislocation Glide and Rapid Degradation
Authors: Maeda K. , Yamashita Y. , Maeda N , Takeuchi S.
Published: March 2011

Conspicuous enhancement of dislocation glides under minority carrier injection is reviewed. Systematic investigation of dislocation glide velocity under electron-beam irradiation in various semiconducting crystals showed that the radiation enhanced dislocation glide (REDG) effect exhibits features expected from the recombination enhanced defect motion (REDM) mechanism. Theoretical analysis, based on the kink diffusion model for the elementary process of dislocation motion, shows that the REDG effect requires enhancement of double-kink formation. An experimental attempt provided an evidence for the smallest double kink formation is the only process that is enhanced by carrier injection. In light of the knowledge available at present, a guide line in device design to minimize degradation in the dislocation glide mode is suggested.
The Origin of Poorly Conditioned Susceptibility Matrix Within Inverse Cvm Algorithm in the Case of PD3V: A Comparison to the Case of NI3V.
Authors: Solal Francine , Finel Alphonse
Published: March 2011

Transition metal alloys are interesting in order to test statistical model based on the Ising Hamiltonian to describe order-disorder phenomena. In the case of such alloys electronic structure calculations all agree that short-ranged pairwise interactions are sufficient to account for phase diagrams and order-disorder properties in general.
Microstructural Benefits of Rsp in a γ-(Ti-Ta-Al) Alloy
Authors: McCullough C. , Valencia J.J. , Levi C.G. , Mehrabian R.
Published: March 2011

Ti-15Ta-48Al alloy samples were characterized after arc melting, controlled supercooling experiments and splat-quenching. It was found that primary b.c.c. (β) forms from the melt in all cases. The arc-button exhibits severe Ta segregation toward the dendrite cores which is substantially alleviated by rapid solidification. Increasing bulk supercooling of the melt reduces the size and scale of segregation and ultimately results in a single phase γ structure. Splat quenching also increases homogeneity and alters the post-solidification transformations in three ways: (i) it suppresses the typical precipitation of γt laths in α2, (ii) it inhibits the formation of σ, and (iii) the Ta-rich areas of the β phase transform to B2 instead of α + σ.
Formation of Cubic Ll2 Phases from Al3Ti and Al3 Zr by Transition Metal Substitutions for Al
Authors: Sparks C. J. , Porter W. D. , Schneibel J. H. , Oliver W. C. , Golec C. G.
Published: March 2011

Alloys of (AlxM1−x)3Ti where M is V, Cr, Mn, Fe, Co, Nb, W, Fe + Ga or Fe + Ga + Mn were fabricated to form the Ll2 cubic phase, tested for ductility, and characterized by lattice parameter, microstructure, quantitative phase analysis, and phase composition. The elements V, Co, Nb, W, Fe + Ga and Fe + Ga + Mn are hereby newly found Ll2 formers in Al3Ti. Both X-ray diffraction and microprobe analysis were used to identify the phases, their volume fractions and compositions. The amount of ternary addition found in the Ll2 cubic phase varied between 4 and 12 atomic percent. This amount of ternary addition decreased as the atomic radius of the elemental addition increased. Pettifor's Mendeleev number was a useful guide in the selection of elements to form the Ll2 phase but did not correlate strongly with the amount of the ternary addition. For the DO23 phase of Al3Zr, the elements V, Mn, and Co were added to the list of Ni, Cu, Fe, and Cr as elements known to form the Ll2 phase. Little if any ductility was observed in these cubic Ll2 phases which readily cleaved with transgranular failure. To achieve ductility and toughness, more than transformation of these compositions from a lower to a higher symmetry crystal structure will be required.