bluuebunny/crossref_metadata_2025_split huggingface dataset:
Solidification Mechanism of Highly Undercooled Metal Alloys
Authors: Shiohara Yuh , Chu Men G. , Macisaac David G. , Flemings Merton C. 
Published: March 2011

ABSTRACTThis paper describes the results of experiments on metal droplet undercooling, and presents a preliminary analysis of the structures obtained. Work was conducted with Sn-25wt%Pb and Ni-34wt%Sn alloys. To achieve the required high degrees of undercooling, emulsification treatments were utilized following techniques described by Perepezko and co-workers.Experiments show the fraction of supersaturated primary phase is found to be a function of the amount of undercooling, as is the fineness of the structures. The solidification behavior of the tin-lead droplets during recalescence was analyzed using three different hypotheses; 1) solid forming throughout recalescence is of the maximumthermodynamically stable composition, 2) partitionless solidification below the “To” temperature, and solid forming thereafter is of the maximum thermodynamically stable composition, and 3) partitionless solidification below the “To” temperature with solid forming thereafter that is of the maximum thermodynamically metastable composition that is possible.
Formation and Stability of Extended Solid Solutions Made by Rapid Quenching from the Melt
Authors: Jones Howard 
Published: March 2011

ABSTRACTExtension of solid solubility by rapid quenching from the melt (RQM) enormously increases scope for alloy development in metals such as aluminium for which solid solubility is particularly limited under equilibrium conditions. The present contribution reviews mainly recent work concerned with matching of experimental observations with predictions affecting:(1)conditions for solidification without change in composition(2)temperatures and modes of deconposition on subsequent heating(3)hardening effects as-quenched and on heat treatment.The significance of such findings for bulk production and consolidation of wrought products for engineering applications is briefly discussed.
Relation Between the Chemical Short-Range Order in Liquid and Amorphous Alloys
Authors: Wagneri C.N.J. , Ruppersberg H. 
Published: March 2011

ABSTRACTRecent advances in both diffraction theory and experiment have led to the determination of the topological and chemical short-range order in liquid alloys and metallic glasses. In binary alloys, three partial interference functions (or partial structure factors) must be determined to evaluate the Warren chemical short-range order parameter α. Examples of recent attempts to determine α in binary liquid and glassy alloys are given. In most glasses, studied so far, evidence exists for the occurrence of unlike nearest neighbor ordering which must be present in the liquid state.
Origin of Defects in MOCVD Growth of GaP on Silicon
Authors: Blakeslee A.E. , Al-Jassim M.M. , Asher S.E. 
Published: March 2011

ABSTRACTWe have studied the nucleation, annealing and growth of GaP on Si substrates. Our findings are very similar to those reported for GaAs/Si. That is, dislocation density after I μm of growth is usually about 108 cm−2 surface morphology is best when a multi-temperature growth process is used and is dependent on the substrate orientation; antiphase domain density is minimized by misorienting the substrates. This commonality of results leads us to conclude that the elimination of interfacial contamination is more important in achieving good epitaxial growth of III-V compounds on Si than is the overcoming of lattice mismatch. In support of this hypothesis we present SIMS data revealing up to 2% of interfacial carbon and TEM observations of an amorphous interfacial phase. The carbon comes from the organometallic source and, we believe, reacts with the Si to form amorphous SiC, which disrupts the coalescence of GaP grains and produces lattice defects.
Epitaxial Growth of GaAs on 4-Inch Diameter Silicon Substrates by OMCVD.
Authors: Salerno Jack P. , Lee J. W. , McCullough R. E. , Gale R. P. 
Published: March 2011

ABSTRACTGaAs epitaxial layers grown on Si substrates up to 4 inches in diameter by OMCVD are characterized with respect to the materials parameters important for their application for device and circuit manufacturing. The layers are characterized using commercial flatness and surface quality measurement instrumentation, x-ray diffraction, Schottky diode
characteristics, and photoluminescence. The 4-inch diameter GaAs epilayers are a singleoriented phase and are of comparable quality to GaAs epilayers grown on smaller diameter Si substrates.
Characterization of Dislocations in GaAs Grown on Si and Ge
Authors: Cho N.-H. , Mckernan S. , Carter C. B. , De Cooman B. C. , Wagner K. 
Published: March 2011

ABSTRACTDislocations are produced at the interface between epilayers and the substrate when there is a lattice mismatch. When GaAs is grown on Ge substrates, these dislocations can propagate into the epilayers. They can then interact with one another or with antiphase boundaries which are generated when the polar-material is grown on a non-polar materials.The interactions between these defects have been investigated using the weak-beam imaging technique of transmission electron microscopy. Possible interactions between the misfit dislocations and heterojunctions were examined in a specially prepared layer structure model of GaAs-AlxGal−xAs.
MO-CVD GaAs Grown by Direct Deposition on Si
Authors: Vernon S. M. , Pearton S. J. , Gibson J. M. , Caruso R. , Abernathy C. R. , Short K. T. , Stavola Michael , Haven V. E. , Jacobson D. C. 
Published: March 2011

ABSTRACTGaAs layers were grown directly on misoriented (2° off (100)→[011]) Si substrates by Metalorganic Chemical Vapor Deposition. The threading dislocation density at the surface of 4 μm thick layers was typically 108cm−2, as determined by both preferential etching and transmission electron microscopy. Rapid thermal annealing (900°C, 10s) improved the crystalline quality of the GaAs near the heterointerface while allowing no detectable Si diffusion into this layer. Two deep electron traps were observed in the undoped GaAs, but were present at a low concentration (∼ 1013 cm−3 ). The (400) x-ray diffraction peak width from the GaAs was significantly reduced with increasing GaAs layer thickness, indicating improved material quality. This is supported by Si implant activation data, which shows higher net donor activity in thicker layers.
Electrical Characterization of Defects in GaAs Grown on Si by MBE
Authors: Chand N. , Fischer R. , Sergent A. M. , Lang D. V. , Cho A. Y. 
Published: March 2011

ABSTRACTWe show that MBE-grown GaAs on Si exhibits only a modest increase in the concentrations of the well-known electron traps typical of MBE-GaAs with no evidence for any new electron deep levels in the upper half of the bandgap in spite of the dislocations and other defects in the material. As shown by Au-GaAs Schottky contacts, the defects are unnoticeable when the device is forward biased but become very active in reverse biased condition, causing large leakage current and low breakdown voltage (although the device is still acceptable for many applications, especially FET's). The defects become more active after hydrogenation and more inactive after a post-growth rapid thermal annealing (RTA). Performance of devices made on thermally annealed GaAs on Si is comparable to those of GaAs on GaAs. Also, following the application of a large- current the device behavior improves, indicating a self-annealing action as a result of internal heating. The reverse current in the as-grown material shows a very weak temperature dependence, indicating its origin is not thermionic emission or carrier generation. It is speculated that a large part of the leakage current in the as-grown GaAs on Si is due to the defect assisted tunneling. After RTA, the average spacing between defect clusters increases, thus reducing the tunneling probability and tremendously improving the device characteristics.
Photoluminescence Study of GaAs/AlGaAs Quantum Wells Grown On Si Substrates
Authors: Jagannath C. , Zemon S. , Norris P. , Elman B.S. , Shastry S.K. 
Published: March 2011

ABSTRACTPhotoluminescence and photoluminescence excitation spectroscopies are utilized to study excitons in GaAs/AlGaAs quantum wells (QW's) fabricated using MBE on MOCVD grown GaAs/Si. The experimental results are understood in terms of the biaxial tension of approximately 3 kbar present in the plane of growth for both the QW's and the GaAs buffer. An important consequence of the biaxial tension is that for QW's with well widths larger than ≈15 nm the light- and heavy- hole sub-bands cross each other in energy. This results in the light-hole exciton energy being lower than that of the heavy-hole exciton, opposite to the case of QW's grown on GaAs substrates.
Optical Characterization Of GaAs/Si: Spectral Features in the Excitonic Region
Authors: Zemon S. , Shastry S. K. , Jagannath C. , Norris P. , Lambert G. 
Published: March 2011

ABSTRACTUsing 4.2 K selective photoluminescence (PL) excitation and PL excitation spectroscopy, the n = 2 excited state of the light-hole exciton is observed for the first time in GaAs/Si. The excited state is about 3 meV above the ground state, similar to exciton results for GaAs/GaAs. A spectral width of 1.8 meV is observed for the ground state transition, the narrowest yet reported.
GexSi1−x/Si Heterostructures: Physics and Device Applications
Authors: Bean John C. 
Published: March 2011

ABSTRACTWork on GexSi1−x strained layer epitaxy is reviewed including: The limits of single layer and superlattice growth, and comparison with theory; Physical properties including bandgap and heterostructure band alignment; Work on non-random alloys; Device applications including MODFET's, PIN and APD photodetectors.
Theoretical Analysis of a Si/SiGe Hemt Structure
Authors: Smith C , Jones M E 
Published: March 2011

ABSTRACTAn analysis has been made of a Si/SiGe HEMT structure, grown on a (001) oriented substrate, by adapting an existing model for III–V HEMT's. Strain plays a critical role in the behaviour of these SiGe structures by separating the degenerate conduction band minimum into 2- and 4- fold symmetric minima. This effect has been incorporated into a ID solution of Poisson's equation in the device structure. The effects of strain, Schottky barrier height, layer width and doping density on both enhancement and depletion mode HEMT properties are all considered. In addition initial estimates of the effect of strain on electron mobility are presented.
Optical Properties of Ordered Ge-Si Atomic-Layer Superlattices
Authors: Pearsall T. P. , Bevk J. , Bean J. C. , Bonar J. M. , Mannaerts J. P. 
Published: March 2011

ABSTRACTA systematic study of the band-to-band optical transitions in commensurate strainedlayer superlattices of Ge and Si grown on (001) Si substrates show the presence of new electronic energy bands. Our measurements suggest that superlattice structure on the same scale as the unit cell results in a band structure significantly different from that of a random alloy.
New Ordering-Induced Optical Transitions in Strained Sige Superlattices
Authors: Froyen Sverre , Wood D. M. , Zunger Alex 
Published: March 2011

ABSTRACTFirst principles total energy and electronic structure calculations for SinGen superlattices grown epitaxially on a Si (001) substrate reveal a nearly direct band gap despite the pronounced indirectness of the Si0.5Ge0.5alloy. While the new direct superlattice transitions have their origin in folded indirect transitions of the random alloy, their transition matrix elements are considerably enhanced by superlattice atomic relaxation and the superlattice ordering potential. For a superlattice grown on a substrate with an lager lattice contant than we predict a nearly direct band gap.
The Nucleation and Growth of GaAs on Si
Authors: Harris J. S. , Koch S. M. , Rosner S. J. 
Published: March 2011

ABSTRACTSubstantial progress has been realized in both understanding the nucleation and growth of GaAs/Si and demonstration of device application of this technology. In this paper, we review the recent progress in the role of the Si surface, initial nucleation, the GaAs/Si interface, GaAs thick layer growth and defect generation and control in the GaAs layer. This last area is the remaining area where substantial progress is still required. Several new approaches for defect control are discussed.
Stress Distribution and Critical Thicknesses of Thin Epitaxial Films
Authors: Sharan S. , Jagannadham K. , Narayan J. 
Published: March 2011

ABSTRACTWe have calculated stress distribution and critical thickness for the growth of strained epilayers having various values of mismatch between the epilayer and the substrate. The present analysis has been carried out assuming that the nucleation of a misift dislocation is controlled by the activation energy. Further, a misfit dislocation is nucleated when the areal strain energy density of the coherent film exceeds the activation energy associated with the misfit dislocation configuration. The latter term has been deternmined using the discrete dislocation method in conjunction with a surface dislocation analysis. The surface dislocation configuration is obtained by minimizing the total energy associated with the two-phase medium. It is verified that the free surface boundary conditions and the continuity of stresses acrosss the interface are satisfied by the surface dislocation array. These energy calculations are expected to be more accurate than those performed by previous workers.
Epitaxy Of GaAs on Si: MBE and OMCVD
Authors: Lee Jhang W. , Salerno Jack P. , Gale Ron P. , Fan John C.C. 
Published: March 2011

ABSTRACTGrowth technique dependent factors are compared for molecular beam epitaxy (MBE) and organometallic chemical vapor deposition (OMCVD) that are related to the GaAs on Si epitaxy. The comparison, both for growth processes and as-grown material characteristics, indicates that material qualities of these layers provided by the two growth techniques are comparable in many aspects, but differ in morphological texture, residual stress, and occasionally Schottky barrier height. These issues are discussed further with our recent OMCVD results in order to ensure the OMCVD advantages for GaAs on Si wafer engineering, which are referred as an easy scale-up and a large throughput.
Heteroepitaxial Si-, Ge-, and Gaas-On-Insulator Structures on Si Substrates by Use of Fluoride Insulators
Authors: Asano T. , Ishiwara H. , Furukawa S. 
Published: March 2011

ABSTRACTHeteroepitaxial growth of alkaline earth fluoride films on Si substrates and Si, Ge, and GaAs films on the fluoride/Si structures, is reviewed. Growth of single crystalline fluoride films on Si is first discussed. Then the usefulness of novel heteroepitaxial technologies, the predeposition method and the electron beam irradiation method, is demonstrated in the growth of Si and Ge films on CaF2/Si structures. Finally fundamental growth characteristics of GaAs films on CaF2/Si structures and annealing effects on the crystallinity of the GaAs films are described.
The Effect of Rapid Thermal Annealing on Heteroepitaxial Structures
Authors: Phillips Julia M. , Batstone J. L. , Pfeiffer L. 
Published: March 2011

ABSTRACTWe present evidence on the types of structural changes caused by the rapid thermal annealing of two types of heteroepitaxial layers: CaF2/CoSi2/Si(111) and Si(100) on A12O3 (1102). We find that grains in a film can be merged into a single crystal and that the microtwin density can be dramatically lowered. We also find a number of changes in the structure of the heteroepitaxial interfaces.
Properties Of Epitaxial Cdte On Si(lll) With a (Ca,Ba)F2 Buffer Layer
Authors: Zogg H. , Blunier S. 
Published: March 2011

ABSTRACTEpitaxial CdTe has been grown onto Si(lll) wafers by MBE with the aid of a composition graded (Ca,Ba)F2 buffer layer to surmount the large misfit of 19%. Untwinned CdTe layers with smooth surfaces, narrow X-ray lines and strong photoluminescence with a narrow near band edge peak were obtained. The results indicate a comparable structural quality to well known CdTe layers on sapphire, InSb or GaAs used as buffers to grow (Hg, Cd)Te for IR-device applications. In addition, the CdTe layers are near strain free despite a large thermal expansion mismatch. This is most probably due to dislocations which are able to move along the fluoride/Si interface even after growth and down to near room temperature.
Silicon Quality Versus Thickness For Novel Silicon On Boron Phosphide Soi Process
Authors: Robertson Perry J. , Dumin David J. , Carver Gary P. , Novotny Donald B. , Freytag Michael 
Published: March 2011

ABSTRACTResults are reported for a single temperature Si-BP-Si process which utilizes 0.2 and 0.4 μm of high resistivity BP covered by a single 1–5 μm silicon epitaxial layer on which PMOS devices were fabricated. Transistor and capacitor measurements were used to characterize the quality of the silicon films. Impurity concentrations on 1.0 and 2.0 μm silicon layers were as high as 3×1017cm−3 due to auto doping from the BP layer. MOS transistors manufactured on these layers did not work properly. Device characteristics improved on thicker silicon layers. The impurity concentration was as low as 1015 cm−3 on the 5.0 μm silicon layers. Surface state densities were found to be as low as 5×1011 eV−1cm−2 with subthreshold currents as low as 10−11 amperes. On all wafers the subthreshold slope varied from 90 to 100 mV/decith little variation due to silicon thickness. Linear and saturation mobilities were process limited with values on the 5.0 μm layers as high as 250 and 160 cm2/V-s respectively. Characteristics of devices fabricated on 5 μm silicon layers were comparable to those of devices fabricated on bulk silicon processed at the same time indicating high quality silicon growth.
Formation of Si-On-Insulator Structure By Lateral Solid Phase Epitaxy
Authors: Miyao. M. , Moniwa K , Kusukawa K , Warabisako T. , Murakami E. , Sinke W. 
Published: March 2011

ABSTRACTFormation of a Si-on-insulator structure by a solid phase process was investigated. Examination by µ-RHEED method revealed that oriented crystal growth propagated from the seeding area by a solid phase epitaxy (SPE) in the low temperature range around 550 °C. In addition . a new local doping method was developed. This realized a relatively large lateral-SPE area on insulating regions (14 µm from the seeding area). Crystal quality and electrical properties of SPE layers were precisely examined utilizing µ-Raman spectroscopy and MOSFET fabrication. A small stress field and high electron mobility comparable to that of bulk Si were obtained.
Lattice Defects in β-Sic Grown Epitaxially On Silicon Substrates
Authors: Pirouz P. , Chorey C. M. , Cheng& T. T. , Powell J. A. 
Published: March 2011

ABSTRACTDefects generated in β-SiC grown on a (001) silicon substrate by chemical vapor deposition (CVD) are charaterized and their mechanism of formation discussed. It is argued that nucleation plays a primary role in this heteroepitaxial system where the lattice mismatch is so large.
Mocvd Growth Of Single Crystal Znsxsel−x On Si
Authors: Sekula Patricia A. , Vernon Stanley M. , Keavney Chris J. 
Published: March 2011

ABSTRACTSingle crystal ZnSxSel−x films have been grown for the first time on (111) Si substrates by low-pressure MOCVD. The epitaxial films clearly show a passivating effect on silicon solar cells, and act as antireflective coatings. Attempts at incorporating Al as an n-type dopant were unsuccessful as the films remain semi-insulating.
The Physics of Metal Base Transistors
Authors: Rosencher E. , Arnaud D'Avitaya F. , Badoz P.A. , d'Anterroches C. , Glastre G. , Vincent G. , Pfister J.C. 
Published: March 2011

AbstractEpitaxial Si/CoSi2/Si structures can be grown under ultra-high vacuum conditions. The metallic CoSi2 films can be extremely thin typically between 1 nm and 20 nm. The electrical properties of these heterostructures are presented, mainly the transport of electrons in the metallic films parallel to the interfaces and the transfer of electrons through the metal ilm. The influence of pinholes in the CoSi2 layers will be discussed.
Characterization of Ultrathin Cosi2 on Si(111) Layers.
Authors: Batstone J.L. , Phillips Julia M. , Gibson J.M. 
Published: March 2011

ABSTRACTUltrathin epitaxial CoSi2 films on Si(111) have been grown in ultrahigh vacuum by room temperature deposition of Co on Si(111) followed by a high temperature anneal at ~600°C. Characterization of the thin films with transmission electron microscopy has revealed pseudomorphic growth up to thicknesses ~30Å. Pinholes present in the pseudomorphic thin films are thought to prevent the trapping of dislocations within the film. A clear transition to films containing a regular network of misfit dislocations occurs at ~40Å. Evidence for the growth of CoSi2 via intermediate metal-rich silicide phases is observed.
Growth of Single Crystal type A and type B CoxNi1-xSi2 Layers on Si(111)
Authors: Tung R. T. , Hellman F. , Gibson J. M. , Boone T. 
Published: March 2011

ABSTRACTSingle crystal type A and type B CoxNi1-xSi2 layers have been grown on Si(111) by deposition of Co-Ni alloy in UHV and annealing. The dependence of CoxNi1-xSi2 layer orientation on the thickness of deposited metal is similar to that observed for pure nickel reaction. Silicon deposition along with the Co-Ni alloy allows the growth of type B oriented CoxNi1-xSi2. Auger, LEED, RBS and TEM analyses suggest that the composition of the ternary silicide layers is inhomogeneous. The advantages and disadvantages of this material in device application will be briefly discussed.
Formation of Epitaxial NiSi2 and CoSi2 On Laterally Confined (111)Si
Authors: Chang C.S. , Nieh C.W. , Chen L.J. 
Published: March 2011

ABSTRACTEpitaxial NiSi2 of single orientation was grown on laterally confined (111)Si. Striking oxide opening size effects on the growth of NiSi2 epitaxy were observed. The formation temperature of NiSi2 on (111)Si was found to be as low as 550°C inside oxide openings 1.8 μm or smaller in size. Epitaxial NiSi2 of single orientation which is identical to that of (111)Si substrate was formed inside oxide openings of or smaller than 1.8, 1, and 0.8 μm in size in samples annealed at 550-750, 800, and 850-900°C, respectively. Preliminary results on the epitaxial growth of CoSi2 are also reported.
Formation Of A Metastable Nisi Phase On <111> Si Induced By Pulsed Laser Irradiation
Authors: Priolo F. , Baeri P. , rimaldi M.G. , Rimini E. 
Published: March 2011

ABSTRACTThermally grown NiSi layers on <111> Si substrates were irradiated by 35 nsec Nd glass laser pulses in the energy density range 0.3−2.0 J/cm2. Time resolved reflectivity measurements were performed during the irradiation to detect surface melting. The samples were analyzed by 2.0 MeV He+ Rutherford Backscattering Spectrometry in combination with channeling effect. The measured threshold for surface melting was 0.5 J/cm2. Irradiation at energy densities higher than 1.3 J/cm2 changed the silicides layer composition because of the mixing with the underlying silicon. In the intermediate energy density range (0.7−1.1 J/cm ) slight changes in composition were observed, a strong alignement of NiSi molecules along the <111> substrate direction was however observed. The measured Xmin was about 30%. It seems then that an epitaxial NiSi phase can be grown by pulsed laser irradiation with a suitable choice of the incident energy density. Work is in progress to identify this new NiSi phase by TEM. However this ordered phase is a metastable one since after anunealing at 250°C, 30min the channeling yield reduction disappeared without any appreciable change in composition.