bluuebunny/crossref_metadata_2025_split huggingface dataset:
Sic-Reinforced Cordierite Composites Formed by Viscous Sintering of Cordierite Powders
Authors: Hardy Anne B. , Rhine Wendell E. 
Published: March 2011

ABSTRACTOne approach for improving mechanical properties of ceramics is to add reinforcing whiskers; however, addition of whiskers often inhibits densification. Formation of SiCcordierite composites by pressureless sintering was studied. The cordierite composites densified by viscous sintering; after densification the amorphous matrix then crystallized. It was shown that high green density composites obtained by using small particle size powder gave the highest sintered density composites. Reducing the aspect ratio of the SiC phase also improved sintered composite densities. Densities greater than 96% were obtained using small particle size cordierite powder formed by a sol-gel process and either classified SiC whiskers or SiC powder at SiC loadings of 20 vol%
Control Over Al2O3 Phase by Use Of Polymer Precursors
Authors: Rees William S. , Hesse Werner 
Published: March 2011

ABSTRACTReaction of Et2AIOEt with ethylene glycol or catechol produced polymers of the general form -[-AI(OEt)-O-R-O-]-n, for R = CH2CH2 or C6H4, respectively. Pyrolytic conversion of these polymers to ceramic materials produced A12O3, at mild (∼500°C) temperatures under a flowing atmosphere of dry air. The crystal phase obtained from the thermolysis is highly dependent upon the degree of cross-linking present in the initial polymer. These results are discussed in terms of the required solid-state atomic reorganization necessary to proceed from polymer to ceramic.
Mixed Metal Oxide Synthesis by Thermolyses of Simple Heteropolymetallic Precursors in Oxygen
Authors: Davies Geoffrey , Giessen Bill C. , Shao Hui-Li 
Published: March 2011

ABSTRACTStepwise transmetalation of the neutral molecular target (µ4-O)N4 Cu4 C16(N is a monodentate pyridine) with M(NS)n transmealators (NS is a monanionic S-methyl hydrazinecarbodithioate ligand, M is Co (n = 2 or 3), Ni or Zn (n = 2)) in aprotic solvents gives a large family of heteropolymetallic products (µ4 - O)N4 (Co,Ni,Cu,Zn)4 C16 that contain from one to four different metals. Thermolysis of these solid products in flowing O2 at 220 - 250°C gives uniform, highly dispersed mixtures of the respective metal oxides. For example, thermolysis of bulk precursor (µ4 -O)N4 CoNiCuZnCl6 gives a uniform mixture of 1 - 2° particles of Co3 O4, NiO, CuO and ZnO.
Epitaxial Nickel Disilicide Formation by Electron Beam Annealing
Authors: Harper R.E. , Maydell-Ondrusz E.A. , Wilson I.H. , Stephens K.G. 
Published: March 2011

ABSTRACTA multiply-scanned electron beam was used to form nickel silicides from thin nickel films on unimplanted and arsenic implanted silicon (100) substrates. Films of thickness 300, 660 and 1000Å were annealed using a power density of 7.9Wcm−2 and irradiation times of 5 to 150 secs.Rutherford backscattering and channelling techniques were used to determine the stoichiometry, thickness and epitaxial quality of the annealed films. The thinnest gave a Xminof ∼ 18% and the thickest a Xmin of ∼ 40%. Resistivities were measured by the four-probe technique. Chemical composition was determined by X-ray and glancing angle electron diffraction (RHEED). Transmission electron microscopy (TEM) was used to estimate grain size of the disilicide phase and scanning electron microscopy (SEM) to study surface textures. The effect of arsenic implantation on growth rate, epitaxial quality and surface texture is demonstrated.
Tin as a Diffusion Barrier For III-V Metallization
Authors: Houghton D.C. 
Published: March 2011

ABSTRACTThe performance of TiN as a diffusion barrier in Au/TiN/InP structures has been studied and compared with Cr and Pt under identical conditions. In order to sensitively monitor interdiffusion, a novel SEM-EDX technique has been used to determine interdiffusion coefficients and activation energies in the temperature range 250–700°C. Extensive intermixing for Cr and Pt was indicated by the SEM-EDX technique and this was confirmed by Auger depth profiling. In addition the heterogeneous formation of the brittle intermetallic phase Au4 in was detected by XRD, and marked the catastrophic failure of the metallization due to delamination. These interfacial reactions and copious interdiffusion may be controlled by a TiN diffusion barrier which remains impervious for periods in excess of 24h at 500°C.
Ion Beam Enhanced Adhesion
Authors: Tombrello T. A. 
Published: March 2011

ABSTRACTWe have shown that the irradiation of a wide variety of thin film-substrate combinations with MeV/amu ions leads to greatly enhanced adhesion. The systems studied include metal films on dielectric, semiconductor, and metal substrates. For metal coatings on semiconductors the electrical contact which is originally diode-like becomes ohmic. Metal films on metal or polymeric substrates generally require the lowest dose irradiations. For Au on Ta the threshold dose to achieve a constant level of adhesion (“Scotch Tape” test) is consistent with a model of the process in which the dose threshold varies with the electronic excitation part of the energy loss in the material as (dE/dx + Q)−2 . The value of Q obtained corresponds to an exothermic reaction due to the increased binding that liberates ˜70 eV at the interface. This model and a variant of it based on the production of K-shell vacancies in low Z elements in the target will be discussed.
Interaction of Al Films on Single Crystal Si Substrates Induced by Ion Irradiation and Post-Anneal
Authors: Hung L. S. , Chen S. H. , Mayer J. W. 
Published: March 2011

ABSTRACTRutherford backscattering and channeling techniques, transmission electron microscopy and Auger electron spectroscopy have been combined to investigate the reordering of implanted amorphous Si in the presence of an Al surface layer and the interdiffusion between these two elements. Recrystallization took place at 200°C and proceeded as the temperature increased. At 350–400°C, better epitaxial layers were obtained and channeling effects became observable. Substantial concentration of residual damage was observed in the regrown layer and persisted to high annealing temperatures. The concentration of Si in the Al film was far beyond the solid solubility at annealing temperatures. When ion implantation was performed at 200°C, the implanted layer was virtually defect free and the diffusion of Si into Al was suppressed.
Interactions between Lattice Dislocations and Interfaces in Solids
Authors: Liu J. S. , Balluffi R. W. 
Published: March 2011

ABSTRACTAttention is focused on the interactions which occur when lattice dislocations impinge on interfaces (i.e., grain boundaries, crystal/crystal interphase boundaries and crystal/amorphous boundaries) in solids. The lattice dislocations can generally dissociate into interface dislocations possessing smaller Burgers vectors under a driving force produced by a decrease in the elastic energy. For crystal/crystal interfaces, a wide range of possibilities exists, depending upon the grain boundary type, which extends from dissociation into a discrete number of interface dislocations to dissociations into a distribution consisting of, in the limit, an infinite number of interface dislocations possessing infinitesimal Bur.ers vectors. For crystal/ anorphous interfaces, the latter model is applicable. Examples of dissociations in these various interfaces are presented. The dissociation geometries and kinetics are described briefly. Some of the wider implications of these phenomena are mentioned.
Formation of Microtwins in Low Angle Grain Boundaries in Germanium
Authors: Elgat Z. , Carter C. B. 
Published: March 2011

ABSTRACTThe structure of a low angle tilt boundary with a [110] misorientation axis and a (111) initial boundary plane in a bicrystal prepared by a hot-pressing technique has been studied. The boundary consists of a periodic array of dislocations as expected but contains a new feature, namely microtwins which lie parallel to the boundary plane. High resolution transmission electronmicroscopy has been used to characterize the boundary structure and to determine the Burgers vector of the dislocations present. The relationship between the structure of the twin-free regions and the twinned regions is discussed.
XPS Study of the Al/SiO2 Interface Viewed From the SiO2 Side
Authors: Hecht M.H. , Grunthaner F.J. , Maserjian J. 
Published: March 2011

ABSTRACTWe report on the first non-destructive measurement of the chemical and physical characteristics of the interface between bulk SiO2 and thick aluminum films. Both X-Ray Photoelectron Spictroscopy (XPS) and electrical measurements of unannealed, resistively evaporated Al films on thermal SiO2 indicate an atomically abrupt interface. Post metallization annealing (PMA) at 450°C induces reduction of the SiO2 by the aluminum, resulting in the layer ordering SiO2/Al2O3/Si/Al. The XPS measurement is performed from the SiO2 side after the removal of the Si substrate after etching with XeF2 gas and thinning of the SiO2 layer with HF:ETOH. This represents a powerful new approach to the study of metal-insulator and other interfaces.
The Chemisorption of Fluorine on Silicon (111) Surfaces
Authors: Mcfeely F.R. , Morar J. , Shinn N. D. , Landgren G. , Himpsel F. J. , Jugnet Y. 
Published: March 2011

ABSTRACTHigh-resolution, soft x-ray photoemission investigations of fluorine chemisorption on silicon (111) surfaces are reported. The distribution of fluorosilyl moieties was found to be strongly dependent upon the surface structure. The 2×1 reconstruction exhibited only monofluoro species, while the 7×7 showed a distribution of mono-, di-, and trifluorosilyl groups.
Thermoelectric Effects Across Solid-Liquid Gallium Interface
Authors: Alvarez J. , Peteves S.D. , Abbaschian G.J. 
Published: March 2011

ABSTRACTA novel technique is described for directly measuring the Seebeck coefficient across the solid-liquid interface of gallium as a function of temperature and crystallographic orientation. The results are compared with those calculated from the absolute thermoelectric power of solid and liquid gallium. The temperature ranges for the measurements were 248 to 302K for solid gallium, and 278 to 353K for the liquid; the liquid was supercooled up to 25K. The effect of crystal orientation on the thermoelectric power of gallium single crystals grown along the a, b, and c axes was investigated. The anisotropy of the thermoelectric power is discussed based on the electronic properties of gallium.
Crystallography and Interfaces of Epitaxial Fluorite Metals and Insulators on Semiconductors
Authors: Gibson J.M. , Tung R.T. , Phillips J.M. , Poate J.M. 
Published: March 2011

ABSTRACTCrystals with the cubic fluorite structure and small lattice mismatches can be grown epitaxially on cubic semiconductors. In this manner thin-film single-crystal metals (NiSi2 and CoSi2) and insulators (e.g. CaF2 , BaF2) have been grown on silicon, germanium and indium phosphide. With close attention to deposition and growth parameters, afforded either by atomically clean conditions or transient thermal processing, great control can be exerted over the crystallography and interfaces of these systems. This has resulted in films with unique physical properties and exceptionally high quality and reproducibility. We review the microstructure of these films in this paper and identify two important new growth regimes for these materials: very thin films (less than 30Å) and transient thermal processing with ultra-fast laser pulses. Examination of the structure of these films, using high-resolution electron microscopy, provides insight into these nucleation and growth processes. One intriguing observation is that all these fluorite structure thin films have an overwhelming tendency to grow with a 180° rotated orientation (B) on (111) semiconductors.
Growth and Characterization of Epitaxial GaAs on Ge/Si Substrates
Authors: Fletcher Robert M. , Ken Wagner D. , Ballantyne Joseph M. 
Published: March 2011

ABSTRACTEpitaxial GaAs layers have been grown on Ge-coated Si substrates. Deposition of epitaxial Ge was performed by electron beam evaporation onto a <100> Si substrate. GaAs was then deposited by organometallic vapor-phase epitaxy. Films grown over large areas (∼1 cm2) and by selective epitaxy in stripe patterns (∼50 μm wide) have been evaluated by a number of techniques to determine structural and electrical properties. In addition, we report what we believe to be the first LEDs fabricated in GaAs/Ge/Si heterostructures.
Tem Study of Pt Silicide Formation on Clean Si Surfaces
Authors: Yokota Y. , Matz R. , Ho P.S. 
Published: March 2011

ABSTRACTThe microstructure of the Pt silicide formed on clean Si surfaces has been investigated using transmission electron microscopy. Pt up to 200Å was evaporated on atomically clean Si (100) and (111) substrates under an ultrahigh vacuum condition. The silicide was formed by annealing up to 600°C for (100) substrates in a purified He atmosphere and in-situ UHV for (111) substrates. For the (100) substrate, as-deposited Pt showed a fine polycrystalline structure with grain size of about 10tm. Upon annealing at 250° to 300°C, formation of Pt silicide was observed, which was primarily PtSi with only a small amount of Pt2Si. The silicide coverage was incomplete below about 1.5nm. Upon further annealing, the fraction of PtSi increased although Pt2Si persisted until 400°C. At 600°C, PtSi showed an epitaxial relationship with its c axis perpendicular to the Si (100) surface. On the Si (111) surface, PtSi formed epitaxially above 400°C. The silicide structure showed a multidiffraction pattern with three-fold symmetry, reflecting the three equivalent but strained epitaxial orientations. A high resolution lattice image technique was used to investigate the details of the epitaxial structures of PtSi on Si (100) and (111) substrates.
Epitaxial Growth of NiSi2 on (011)Si
Authors: Chen L.J. , Lin W.T. , Chang M.B. 
Published: March 2011

ABSTRACTEpitaxial growth of NiSi2 on (011)Si was investigated by the transmission electron microscopy. Both epitaxial and twin related NiSi2 were formed, with the former being predominant, in samples annealed at 850°C for 1/2 h. The silicides were faceted with {111} interfaces being more prominent than {100} interfaces. Interfacial dislocations were found to be of edge type with 1/6<112> Burgers vectors. The average spacing is about 700 Å which is very close to the theoretically expected value 670 Å.The absence of twins formed on (111) and (111) planes for (011) samples as well as the results obtained for (001) and (111) specimens suggest that there exists a critical resolved shear stress at the interface for the initiation of the formation of twin related NiSi2.
Superlattice Interface and Lattice Strain Study by Ion Channeling
Authors: Pan C. K. , Zheng D. C. , Chu W. K. , Chang C.-A. 
Published: March 2011

EXTENDED ABSTRACTWe have studied the interface and the lattice strain of superlattices by ion channeling technique. The objective in this work is to verify the existence of alternating tensile and compressive strain in the superlattice and to develop a method for measuring the lattice strain directly. Alternating layers of GaSb/Al Sb were grown epitaxially by MBE with 10 periods. The thickness of each individual layer is 30 nm. Channeling measurements and analysis were made using a 1.76 MeV 4He ion beam. The measurements reveal higher dechanneling along the [110] axis than along the [100] axis. This is consistent with the dechanneling results published earlier. The high dechanneling along the [110] axis has been considered due to the lattice strain that occurs in the layers caused by the slight mismatch between the lattice constants of the two materials. The strain effect make [110] axis slightly bent from layer to layer (“zigzag”), but it does not occur in [100] axis. The axial angular scan analyses were made around the [110] direction at the different depths using a movable energy window setting. We have found that the angular position of the best alignment shifts from layer to layer. The oscillation of those angular positions with depth is of a direct evidence of the existence of alternating tension and compression strain layers in the superlattice. The “kink” angle at the interface is given by the difference of the angular position between the first and second layer. This is found to be 0.17° ± 0.03 %. This is in a good agreement with the result calculated from elasticity. Preliminary result of this experiment is recently published.3We are also investigating the interface and lattice strain by planar angular scan across the (110) plane at a position three degrees from [110] axis.The similar oscillatory results have been found for {110} planar channeling and the “kink” angle measurement is in a good agreement with the results from axial angular scan.We believe that the method of ion beam channeling and angular scan is very effective in strain measurements in multi-layered heteroexpitaxy system.3. W. K. Chu, C. K. Pan and C.-A. Chang, Phys. Rev. Rapid Communication B28, 4033 (1983).
Lateral Solid Phase Epitaxy of Evaporated Amorphous Si Films onto SiO2 Patterns
Authors: Yamamoto H. , Ishiwara H. , Furukawa S. , Tamura M. , Tokuyama T. 
Published: March 2011

ABSTRACTLateral solid phase epitaxy (L-SPE) of amorphous Si (a-Si) films vacuum-evaporated on Si substrates with SiO2 patterns has been investigated, in which the film first grows vertically in the regions directly contacted to the Si substrates and then grows laterally onto SiO2 patterns. It has been found from transmission electron microscopy and Nomarski optical microscopy that use of dense a-Si films, which are formed by evaporation on heated substrates and subsequent amorphization by Si+ ion implantation, is essentially important for L-SPE. The maximum L-SPE length of 5–6μm was obtained along the <010> direction after 10hourannealing at 600°C. The kinetics of the L-SPE growth has also been investigated.
Abnormal Grain Growth in Ultra-Thin Films of Germanium on Insulator
Authors: Yonehara T. , Tihompson C.V. , Smith Henry I. 
Published: March 2011

ABSTRACTThe growth of large secondary grains with (112) texture, and solid-state agglomeration to single-crystal islands have been observed by annealing ultra-thin (less than 1000Å) films of Ge. A driving force proportional to surface-energy anisotropy and inversely proportional to film thickness is believed to be responsible for both phenomena. The temperature for agglomeration decreases with film thickness, and is further depressed by the presence of Sn vapor. Patterning Ge into stripes increases secondary grain size and population. Encapsulation with a film of SiO2 suppresses agglomeration and alters crystallographic texture. A surface-relief structure of 0.2μm period and 300Å depth induces a (100) texture in some cases, and alters the morphology of agglomerated islands.
Specific Contact Resistance Measurements on Multilayer Interconnect Structures.
Authors: Harrison H.B. , Reeves G.K. 
Published: March 2011

ABSTRACTAn integral part of very large scale integrated (VLSI) circuits is the multilayer structures for electrical interconnection and insulation. Many conducting materials are used for interconnection including polysilicon, silicon, silicides, polycides and metals. An important point in considering these materials is the interconnection between them and the corresponding characterization of the interface by way of the specific contact resistance, which directly affects the interfacial contact resistance.For a planar ohmic contact formed between a metal and any layer with a much larger sheet resistance (for example single crystal silicon) a technique based on the transmission line model provides a method of characterizing these contacts. However, for planar contacts between layers with comparable sheet resistivities for example polysilicon to single crystal silicon this technique must be modified. In this paper we review the transmission line approach used to obtain the specific contact resistance between such layers and provide initial results of measurements made on the poly to single crystal interface. We also present a series of test structures, currently under fabrication that will provide more detailed experimental data.
Tem Studies of Cosputtered Tisi 2 Films Containing Excess Silicon.
Authors: Beyers R. , Sinclair R. , Thomas M. E. 
Published: March 2011

ABSTRACTThe effect of excess silicon on the growth and microstructure of cosputtered TiSi 2 was investigated. Cosputtered films, with Si/Ti ratios between 2.5 and 4.5, were deposited on (100) Si substrates and reacted at temperatures from 650° to 1050°C. Excess Si in the asdeposited films formed a layer of epitaxial Si on the Si substrate. In addition, Si and SiO2 precipitates formed within the grains. The films became discontinuous when reacted at 1050°C.
Rectifying Structures Resulting from Gold, Cadmium and Thallium Deposited on Selenium
Authors: Champness C.H. , Nerguizian V. , Nerguizian C. , Chan A. 
Published: March 2011

ABSTRACTStructures of the form Al-Bi-Se-metal were fabricated by deposition of the metals gold, cadmium, bismuth and thallium as thin films on a layer of crystallized selenium. The selenium was itself evaporated on a layer of bismuth on an aluminum base. This Al-Bi-Se base contact was rendered ohmic by substrate heating during the selenium deposition. The diodes showed forward-to-reverse current rectification ratios ranging from large for thallium to small for gold. At small forward voltage, the current density increased with increasing work function from thallium to gold, whereas the voltage intercepts Vo on plots of (capacitance)−2 versus reverse voltage decreased with increasing work function. From these Vo values and the slopes of the latter plots, barrier heights were deduced and plotted against work function. From this plot showing a decrease of barrier height with decreasing work function, it was possible to estimate an interface state density of 1013 cm−2 volt−1 assuming the existence of an interfacial layer 100Å in thickness. While the Se-Tl contact showed excellent rectification, it exhibited rapid degradation with time from atmospheric oxidation.
Pt and Pd Silicides and Pd Germanide as Contact Metallizations for GaAs
Authors: Marshall E. D. , Wu C. S. , Scott D. M. , Lau S. S. , Kuech T. F. 
Published: March 2011

ABSTRACTRefractory metal silicides have been shown to form stable Schottky barriers on GaAs up to an annealing temperature of ∼850°C. In this study, the metallurgical and electrical stability of near noble metal (Pd and Pt) silicide contacts to GaAs have been investigated. It is observed that Pd and Pt silicides are metallurgically more stable than Pd and Pt alone on GaAs. A correlation between the stability of silicide contacts and the heat of formation of the silicides normalized to per metal atom is found, thus allowing the prediction of contact stability of other silicides on GaAs. We have also investigated the feasibility of using solid-phase epitaxy (SPE) to grow a highly doped Ge epitaxial layer on GaAs to form a non-alloyed ohmic contact. This approach of forming a Ge/GaAs heterojunction alleviates the high vacuum requirement of MBE techniques. Our preliminary results indicate that relatively low contact resistivities can be obtained by SPE using the Ge-Sb-Pd system.
Removing Grain Boundary Effects in Polycrystalline Silicon Using a Minority Carrier Mirror Concept
Authors: Kai F. Y. T. , Jackson M. A. , Thayer M. , Anderson W. A. 
Published: March 2011

ABSTRACTThe boron minority carrier mirror (MCM) concept has been applied to Wacker poly-Si for passivation of active grain boundaries (GB). Photovoltaic, spectral response, laser beam induced current, electron beam induced current and interface state data show the MCM process to significantly improve solar cell performance. For example, an efficiency improvement from 6.4% to 8.8% was observed in part of the study. This appears to be a simple technique to produce stable solar cells with future application to fine grain poly-Si.