bluuebunny/crossref_metadata_2025_split huggingface dataset:
Columnar and Subsurface Silicide Growth with Novel Molecular Beam Epitaxy Techniques
Authors: Fathauer Robert W. , George Thomas , Pike W. Thomas 
Published: March 2011

ABSTRACTMolecular beam epitaxy of silicides is conventionally carried out at temperatures ≤500°C, with stoichiometric Si:metal flux ratios or deposition of pure metal. We have found novel growth modes for epitaxial CoSi2 at high temperatures coupled with Si-rich flux ratios or low deposition rates. In the first of these modes, codeposition of metal and Si at 600-800°C with excess Si leads to the formation of epitaxial silicide columns surrounded by single-crystal Si. During the initial stages of the deposition, the excess Si grows homoepitaxially in between the silicide, which forms islands, so that the lateral growth of the islands is confined. Once a template layer is established by this process, columns of silicide form as a result of selective epitaxy of silicide on silicide and Si on Si. This growth process allows nanometer control over silicide particles in three dimensions. In the second of these modes, a columnar silicide seed layer is used as a template to nucleate subsurface growth of CoSi2. With a 100 nm Si layer covering CoSi2 seeds, Co deposited at 800°C and 0.01 nm/s diffuses down to grow on the buried seeds rather than nucleating surface silicide islands. For thicker Si caps or higher deposition rates, the surface concentration of Co exceeds the critical concentration for nucleation of islands, preventing this subsurface growth mode from occurring. Using this technique, single-crystal layers of CoSi2 buried under single-crystal Si caps have been grown.
Relaxed Si1−xGex Layers on Simox Avoiding a Lattice Mismatched Heterointerface
Authors: Holländer B. , Mantl S. , Butz R. , Michelsen W. , Dieker Ch. 
Published: March 2011

ABSTRACTFor the first time, Si1 xGex layers on amorphous SiO 2 were produced by modification of the Si surface layer of a SIMOX wafer. We used two alternative methods. An additional Si1.. Gey layer was deposited epitaxially on a SIMOX wafer followed by rapid thermal annealing. Diffusional intermixing of the layers produced a homogeneous Si1 xGex layer on SiO 2. In a second attempt, Ge was implanted into the Si surface layer and thermally treated. In both cases epitaxial Si1 xGex layers on SiO2 with minimum yield values around 9% were obtained. Rutherford backscattering and cross sectional transmission electron microscopy were used to characterize the new structures.
The Influence of Surfactants on the Growth of Germanium Layers on Silicon Surfaces by MBE
Authors: Osten H.J. , Klatt J. , Lippert G. , Bugiel E. , Dietrich B. 
Published: March 2011

ABSTRACTDeliberate introduction of a surfactant can drastically influence the growth mode of germanium on silicon. Without a surfactant germanium growth proceeds in a typical Stranski-Krastanov mode. The system is minimizing its built-in energy by undergoing strain relaxation through a clustering mechanism (islanding). In all surfactant-mediated growth processes it was possible to obtain smooth layers without island formation. The influence of different ways for introducing the surfactant layer (at the interface between substrate and growing film, in the growing film below the critical Stranski-Krastanov thickness, or on top of the grown Ge film) will be presented. Especially in surfactant-controlled solid phase epitaxy (SPE) the smooth epitaxial germanium layer was obtained by passing through an island formation stage. These islands formed below 400 °C are of different structure than the ones formed without a surfactant. Possible mechanism for the “smoothing out” of islands developed in the beginning stage of surfactant-controlled SPE will be proposed. The island formation stage can be completely suppressed by depositing the surfactant on top of the amorphous Ge layer before increasing the temperature.
Modeling of Silicon Deposition Yield at Low Temperature by ArF Excimer Laser Photolysis of Disilane
Authors: Fowler B. , Lian S. , Krishnan S. , Li C. , Jung L. , Samara D. , Manna I. , Banerjee S. 
Published: March 2011

ABSTRACTNon-thermal Chemical Vapor Deposition (CVD) such as laser-enhanced photo-CVD of Si at low temperatures is important for Si-based heterostructures and doping superlattices. Growth kinetic models must be developed to allow these processes to be fully exploited. Intrinsic Si epitaxial layers were deposited at low substrate temperatures of 250-350ºC using the 193 nm output of an ArF excimer laser to directly dissociate Si2H6. The intrinsic film deposition rate can be described by a kinetic model that considers the gas phase reactions of the primary photolysis products and diffusion ofsilicon-bearing molecules to the growth surface. With the laser beam tangential to the substrate surface, growth rates as a function of beam-to-substrate distance have been characterized and indicate that very little gas phase reaction occurs for the dominant Si growth precursor. In order for intrinsic film deposition to result solely from Si2H6 photolysis products, a sticking coefficient ≥ 0.6 must be assigned to the dominant growth precursor in order to fit the observed yield of Si deposited in the films, indicating that the dominant growth precursor in 193 nm Si2H6 photolysis is perhaps H2SiSiH2.
Heteroepitaxial Growth of GexSi1−x Strained Layer on Si by RRH/VLP—CVD
Authors: Youdou Zheng , Rong Zhang , Liqun Hu , Shulin Gu , Ronghua Wang , Ping Han , Ruolian Jiang 
Published: March 2011

ABSTRACTA rapid radiant heating, very low pressure CVD (RRH/VLP—CVD) has been successfully applied to GexSi1−x strained layer epitaxy on Si using SiH4' GeH4' B2H6 and PH3 as reaction gases at low temperature ranging from 550 to 650ĉ for operation pressure around mTorr. High quality GexSi1−x/Si strained layer heterostructure and superlattice were fabricated and high electrically active in—situ boron doping in GexSi1−x epilayer was also successfully achieved.
On Microfaceting Instability of Pt(110) Under Catalytic Oxidation of Adsorbed Co
Authors: Papoular M. 
Published: March 2011

ABSTRACTAs demonstrated by recent STM [1] and LEED [2] experiments the platinum (110) surface undergoes, at carbon monoxide submonolayer coverages, a phase transition from the 1 x 2 “missing-row” (reconstructed) state to the 1 x 1(bulk-like) state under specific temperature and partial-pressure conditions. The catalytic oxidation reaction CO + 1/2 → CO2 drives a microfaceting instability [3] [4] of the Pt(110) surface which ends up in a regular sawtooth profile with a period ≈ 200 Å, along the [110] direction.We introduce the idea that the rather extensive Pt mass transport, as involved in the process, could be energetically assisted by the reaction itself. Energy and momentum-balance considerations lead us to expect an energy ≲ 0.5 eV to be transferrable to thesubstrate. This should efficiently contribute to initiating the “scraping”process that leads to the microfaceted pattern.A simple model for nucleation and growth of facets is presented (see ref. 5), yielding characteristic times of order minutes (at T = 500 K), in fair agreement with experiment.Independently of the structural/catalytic problem, adsorption of CO at submonolayer coverages on, e.g., Pt(110) might be of interest from a surfactantphysics point of view (see ref. 6 for a very recent study on layer-by-layer homoepitaxial metal growth).
Interdiffusion in MBE-Grown Symmetrically and Asymmetrically Strained Si/Si1−xGex Superlattices Investigated by Ion Scattering
Authors: Holländer B. , Butz R. , Mantl S. 
Published: March 2011

ABSTRACTThe interdiffusion in MBE-grown Si/Si1−xGex superlattices was measured by Rutherford backscattering spectrometry. The superlattices consisted of 5 periods of 100 !A Si and 100 !A Si1−xGex layers with Ge concentrations, x, between 0.20 and 0.70. Both, asymmetrically strained superlattices, grown on Si(100), as well as symmetrically strained superlattices, grown on relaxed Si1−y.Gey buffer layers were investigated. Rapid thermal annealing in the temperature range between 900°C and 1125°C leads to significant interdiffusion between the individual layers, indicated by a decrease of the amplitudes of the backscattering spectra. Interdiffusion coefficients were deduced using a Fourier algorithm. The interdiffusion coefficients follow an Arrhenius law for a given Ge concentration. The interdiffusivity increases significantly with increasing Ge concentration.
A Study of Interdiffusion, Crystallinity, Strain and Thermal Stability of Si1−xGex/Si Created Using Pulsed Laser Induced Epitaxy (PLIE)
Authors: Kramer K.-Josef , Talwar S. , Weiner K. H. , Sigmon T. W. 
Published: March 2011

ABSTRACTHeteroepitaxy of Sil−xGex alloy layers on Si(100) and Si(111) has been achieved using Pulsed Laser Induced Epitaxy (PLIE). The energy of 1-50 pulses from a spatially homogenized XeCl excimer laser is used to melt a structure of electron beam evaporated Germanium on Silicon substrates. On Si(100) substrates alloys with Germanium fractions between 6 and 22% are investigated and exhibit very good crystallinity, as confirmed by MeV-Ion Channeling along the <100> - direction. Heteroepitaxy on Si(l11) yields similar results. MeV-Ion Channeling is also used to determine the level of strain in the layers. This is done by comparing angular yield curves around the <110> - direction for substrate and alloy layer. The obtained strain values are close to calculations for an ideally strained layer state. The strain is also measured for layers that have been subjected to different thermal cycles. As a result of this, predictions of feasibility for subsequent device fabrication can be made for the layers.
Differences in The Growth Mechanism of InxGa1−xAs on GaAs Studied by The Electrical Properties of Al0.3Ga0.7As/InxGa1−xAs Heterostructures (0.2 ≤ × ≤ 0.4)
Authors: Schweizer T. , Köhler K. , Ganser P. , Hiesinger P. , Rothemund W. 
Published: March 2011

ABSTRACTLattice mismatched InxGa1−xAs layers with InAs mole fractions below 0.25 grow in a two dimensional growth mode on GaAs. If the thickness of these layers is beyond the critical layer thickness the strain relaxes through misfit dislocations. The misfit dislocation density in the <011> and <01-1> direction differs for n-type layers. This results in a highly anisotropic electron mobility for GaAs/InxGa1−xAs/Al0.3Ga0.7As inverted HEMT structures. A higher electron mobility in the < 011 > direction is measured in comparison to the <01-1> direction. The resistance ratio in the two perpendicular directions exceeds 105. For a three dimensional growth mode, the InxGa1−xAs layer shows interface roughness which degrades the transport properties of the normal Al0.3Ga0.7As/ InxGa1−xAs/ GaAs HEMT structures more than the inverted GaAs/InxGa1−xAs/ Al0.3Ga0.7As HEMT structures. For a three dimensional growth mode, an anisotropic electron mobility for Al0.3Ga0.7As/InxGal, As/GaAs HEMT structures is also observed. For these structures the highest electron mobility is measured in the < 01-1 > direction. This anisotropy could be explained by anisotropic growth rates in the <011> and < 01-1 > directions which results in growth islands with asymmetric extensions.
Selected-Area Epitaxy of CdTe on GaAs with A Cantilever Shadow Mask
Authors: Dhar N.K , Boyd P. , Martinka M. , Benson J.D. , Dinan J.H. , Iliadis A.A. 
Published: March 2011

ABSTRACTA cantilever shadow masking technique has been used for the first time to grow CdTe in recesses of GaAs wafers. The use of this technique eliminated the deleterious effects of side wall growth. Scanning electron microscopy, electron channeling, Auger spectroscopy and photoluminescence were used to characterize these structures. An application to planar monolithic infrared focal plane arrays is discussed.
Dopant Distribution and Electrical Characteristics of Boron-Doped Si1−xGex/Si p+/N Heterojunction Diodes Produced by Gas Immersion Laser Doping (GILD) / Pulsed Laser-Induced Epitaxy (PLIE)
Authors: Kramer K.-Josef , Ishida E. , Talwar S. , Weiner K. H. , Carey P. G. , McCarthy A. M. , Sigmon T. W. 
Published: March 2011

ABSTRACTPulsed Laser-Induced Epitaxy / Gas Immersion Laser Doping is used to create borondoped heteroepitaxial p+/N Si1−xGex/Si layers and diodes. Borontriflouride is used as the gaseous dopant source. The mechanisms of heteroepitaxial layer growth of Si1−xGex using PLIE are described and impurity incorporation from the gas phase into the molten layer is investigated. Compared to other heteroepitaxial techniques, very different process parameters determine the growth. The energy fluence of the pulsed laser beam determines the melt depth and thus the layer thickness; Si and Ge intermix in the liquid phase, the diffusion of B dopant also depends on its diffusivity in the liquid phase. Boron incorporation is investigated as a function of laser energy fluence and number of laser pulses using SIMS and Hall-effect measurements. The dose of incorporated dopant is on the order of 1013cm−2 per pulse. The obtained boron profiles are flat except for a pile-up at the interface which is due to segregation. Boron and Germanium distribution are compared to turn-on voltage shifts obtained from p+/N Si1-xGex/Si heterojunction diodes fabricated with the technique. A two-step Laser process to independently control metallurgical and electrical junction depth of the diodes has been implemented. The selective nature of the epitaxial process is emphasized.
Initial Stage of InGaAs Growth on GaAs(100)
Authors: Gerthsen D. , Lentzen M. , Förster A. 
Published: March 2011

ABSTRACTThe growth mode and the relaxation of MBE grown InxGa1-xiAs layers (0.13 ≦ x ≦ 1.0, nominal film thickness 5 nm) on GaAs(100) substrates with a lattice-parameter mismatch were investigated by transmission electron microscopy (TEM). The transition between two- and three-dimensional growth occurs at x ≈ 0.4. The three-dimensional growth mode for x ≥ 0.6 results in a wide spectrum of island sizes. In contrast to the two-dimensional growth mode, the strain state of a three-dimensionally growing layer is completely inhomogeneous because the relaxation of the strain is correlated with the island size. The reduction of elastic strain for islands is reasonably described by an energy balance model.
Strain Relief in SrF2 Epitaxial Films on Si(111) Substrates
Authors: Li Weidan , Taylor Anthony P. , Schowalter Leo J. 
Published: March 2011

ABSTRACTMolecular beam epitaxial (MBE) growth condition of SrF2 directly on Si(111) substrates has been optimized in terms of both Xmin and the surface morphology. Lattice distortion measurements were carried out with ion channeling along off-normal channeling directions in the strained layers grown at the optimal condition. The relationship of residual strain vs. film thickness for SrF2 on Si(111) was provided by the first time. The experimental data demonstrated a special thickness in this relation, at which the derivative of strain vs. film thickness changes its sign. This unique behavior was understood as the result of competition between the large lattice mismatch and the large thermal mismatch between SrF2 and Si.
Strain Relief in InxGa1−xAs/GaAs Multiple Layer Systems
Authors: Krishnamoorthy V. , Lin Y.W. , Park R.M. 
Published: March 2011

ABSTRACTIn a recent paper[l] we presented the notion of a “critical composition” of InxGa1−xAs (x=0.18) which when exceeded results in threading dislocation evolution in InxGa1−xAs (x ≥ 0.18) material grown on GaAs. For InxGa1−xAs compositions below x=0.18, threading dislocation evolution occurs in the GaAs substrate material but not in the InxGa1−xAs epitaxial layer material, this phenomenon being attributed to a yield strength mismatch in favor of InxGa1−xAs at the epilayer growth temperature.In this paper we describe recent results concerning an extension of this work to the study of strain relief in multiple layer systems. It was found that large x (x-0.5) InxGa1−xAs/GaAs layers can be grown having extremely low dislocation densities (<104/cm2 ) by step increasing the InxGa1−xAs composition at a series of InxGa1−xAs/InyGa1-yAs heterointerfaces such that a “critical composition difference” is not exceeded at each heterointerface. High resolution x-ray diffraction analysis was used to determine the extent of relaxation in each layer of these multilayer systems. As evidenced by cross-sectional TEM analysis, dislocations propagate only in the underlying material at each heterointerface for suitably selected compositional differences which results in the top InxGa1−xAs layer in such multiple layer schemes having a low dislocation density. It is to be noted that conventional methods for blocking dislocations such as strained layer superlattices and compositionally graded layers were not employed in our multilayer systems.
Tem Assessment of Different Mechanisms Contributing to Stress Relaxation in Strained InGaAs/InAlAs Systems
Authors: Peiro F. , Cornet A. , Morante J.R. , Clark S. A. , Williams R.H. 
Published: March 2011

ABSTRACTA study by Transmission Electron microscopy (TEM) of strained InGaAs/InAlAs systems on InP substrates is presented. The influence of the lattice mismatch, epilayer thickness and modulation of the lattice parameter on the morphology of the system is analyzed. A discussion of the strain relaxation mechanisms occurring for each growth morphology is also presented.
Strain Relaxation Via Interface Nucleation of Misfit Dislocations in Intermixing Layers
Authors: Park Hyo-Hoon , Lee Jung Kee , Lee El-Hang , Lee Jeong Yong , Hong Soon-Ku 
Published: March 2011

ABSTRACTThe strain relaxation mechanism via the homogeneous nucleation of misfit dislocations from interface during interdiffusion in lattice-matched semiconductor heterostructures has been investigated. Transmission electron microscopy studies in intermixed GaInAsP/InP heterostructures revealed that the critical interdiffusion depth for the nucleation of 90° 1/6<112> partial dislocations from a tensile interface is much shallower than that of 60° 1/2<110> perfect dislocations from a compressive interface. A critical thickness model for the interface nucleation of these dislocations is developed as a modification of the classical surface nucleation'model.
AFM Study of Film Growth Kinetics in Heteroepitaxy
Authors: Tong William M. , Snyder Eric J. , Williams R. Stanley , Yanase Akihisa , Segawa Yusaburo , Anderson Mark S. 
Published: March 2011

ABSTRACTThe growth of CuCl/CaF2 heterostructures has been studied with an atomic force microscope (AFM). We have grown by molecular beam epitaxy (MBE) CuCl thin films at various substrate temperatures and thicknesses on CaF2(111) substrates. AFM studies reveal that islanding is the dominant growth mechanism. We calculated the height-height correlation function, 〈lh(qt)|2〉, for each of our films and compared them to the predictions made by the Shadowing Growth Theory, a preexisting growth model that enabled us to extract the important kinetic parameter of surface diffusion length for the growth condition of each of the four films.
MBE Growth and Characterization of CdTe, ZnTe Epilayers and CdTe/ZnCdTe Superlattices on GaAs Substrates
Authors: Milokhin A.E. , Trofimov I.E. , Petrov M.V. , Balakirev F.F. , Kuzmin V.D. , Kalinin V.V. , Sidorov U.G. 
Published: March 2011

Semiconductor heterostuctures ZnxCd1−xTe/CdTe were found to be of interest recently due to their potential practical usage. The reason for this is the beautiful variety of electrical heterostucture properties which arise from the strong influence of elastic deformation distribution. Thin epilayer films and superlattices ZnxCd1−xTe/CdTe were prepared on GaAs semi-isolator substrates by MBE technology with RHEED oscillation measurements of the deposited layers. X-ray measurements have shown high crystalline quality of the samples.We have performed Raman scattering studies of ZnxZnxCd1−xTe/CdTe structures. The data obtained were interpreted as a proff of the pseudomorphous growth model. That is, ZnxCd1−xTe/CdTe SLS keeps the lattice constant of the buffer layer.
Experimental Measurement and Analysis of Microelectronics Application Polymer Materials Properties
Authors: Jeng Y.H. , Lii Mirng-Ji 
Published: March 2011

AbstractA laser based surface scanning technique was utilized to measure the polyimide coated silicon wafer curvature resulting from thermal cycling and mismatch, Meanwhile, mechanical properties of polyimide thin film were characterized by DMA, TMA and tensile test. Based on the obtained material properties, A FEA model was developed to analyze the experimental results -reasonable correlation was obtained.Similar approaches were taken one step further in the MCM silicon substrate curvature measurement. In a MCM package with silicon substrate, epoxy adhesive, and ceramic package, substrate warpage was developed in a thermal cycle due to thermal mismatch between the substrate and the package and coupling effect linked by epoxy adhesive. Three different substrate curvature measurement techniques were applied to identify the substrate curvature and epoxy thin film properties were also well characterized. A 3D FEA model incorporating with the epoxy material properties was developed to analyze the substrate warpage and investigate an optimal package design.
X-Ray Determination of Residual Stresses of Encapsulated Thin Aluminum Lines
Authors: Radler M. J. , Crowder C.E. , Shaffer E.O. , Townsend P.H. 
Published: March 2011

AbstractDifferences in thermal expansion coefficients between the dielectric layers, the substrate, the metallizations, and the circuit chips generate complex residual stress fields within multichip module (MCM) packages. For example, encapsulated interconnect lines in a typical MCM are under triaxial stress. Quantifying the triaxial stress is needed to understand critical issues such as stress relaxation, stress-induced voiding, as well as providing benchmarks for finite element calculations. Employing a novel sample design, triaxial residual stresses have been determined in thin aluminum lines encapsulated in benzocyclobutene dielectric layers by x-ray diffraction techniques. Significant differences are observed in the stresses if the lines are deposited on the Si substrate or on intervening polymer layers. The stress level is constant with intervening polymer layer thickness. The results suggest a fundamental difference between the strain transfer across the silicon oxide-aluminum interface relative to the silicon oxide-polymer interface.
Effects of Electronics Assembly Processes on Benzotriazoletreated Printed Wiring Board Copper Surfaces.
Authors: Evans Howard E. , Partridge Julian P. , Miller Allen G. , Jackson Marc W. 
Published: March 2011

AbstractThe performance and reliability of personal computers, workstations and other electronic products depend on the effective soldering of electronic components to printed wiring oards (PWBs). The copper surfaces of PWBs are frequently treated with benzotriazole (or similar organic complexes) to preserve solderability by preventing copper oxide formation. However, new assembly process techniques and more complex processes may degrade protective organo-copper surface complexes and allow copper oxidation to occur, thus inhibiting subsequent solder operations. This study uses Auger electron spectroscopy (AES) in conjunction with meniscograph wettability results to determine the effects of processing conditions on the solderability of PWB surfaces. Effects are characterized for aging up to 19 months; Infrared (IR) reflow in air and nitrogen; cleaning; and temperature cycles associated with adhesive or encapsulant cure. Surface compositions, oxide thicknesses, and solderability measurements are correlated to the above process steps. For example, IR reflow in air increases oxide thickness from ∼10 Å to ∼150Å (relative to sputtering rates in Ta2O5 with an attendant increase in the meniscograph time-to-neutral-buoyancy from <2 seconds to >10 seconds, relative to unprocessed PWBs. Such fundamental information serves as an invaluable complement to standard phenomenological observations of defective solder joints, and can aid in guiding processing decisions for improved yield and reliability.