bluuebunny/crossref_metadata_2025_split huggingface dataset:
Interfacial Reactions and Phase Stability in the Ni/InP System
Authors: Mohney Suzanne E. , Austin chang Y. 
Published: April 2011

ABSTRACTNickel is widely used in electrical contacts to InP, especially in NiAuGe ohmic contact to n-type InP. Several researchers have even suggested that the reaction of Ni with InP plays an important role in the ohmic nature of Ni-based contacts. However, numerous discrepancies are found in the literature concerning the Ni/InP reaction. In this study, an examination of the phase equilibria in the Ni-In-P system aids in an interpretation of bulk and thick film diffusion couples, and many of the apparent discrepancies in the literature are clarified. Finally, minor variations in the processing of the contacts (changes in the annealing gas and substrate cleaning procedure) are found in this study to have a less important role in altering the Ni/InP reactions than previous researchers have suggested.
Composition and Structure of as-Deposited and Oxidized Dcs-Based Cvd WsiX Films
Authors: Moinpour Mansour , Moghadam Farhad , Cham Johnny , Lu Wen-Juei 
Published: April 2011

ABSTRACTCVD WSix films have been widely employed for ultra thin gate and bit-line applications. Recently, for sub 0.5 μm technologies based on CVD WSix polycide gates and interconnects, efforts have been made to replace the silane-based deposition chemistry with that based on dichlorosilane (DCS) reduction of tungsten hexafluoride (WF6). Fluorine-contaminated gate oxides and poor film adhesion and cracking (especially after high temperature annealing/oxidation) are main characteristics of silane-based WSix which could be detrimental for fine geometries of sub 0.5 |im technologies. In this paper, the composition and structure of DCS-based CVD WSix films were studied. WSix films were deposited on 200 mm, implanted polysilicon substrates; silicide film thickness ranging from 60 to 200nm. A high temperature furnace anneal and oxidation cycle was used to examine post-oxidation film properties. SIMS, RBS and X-ray diffraction (XRD) were used to determine film composition profile, structure and texture on both as-deposited and annealed/oxidized films. Si/W uniformity through the depth of the film, for both W-rich and Si-rich interfaces, and its impact on film adhesion and cracking were studied. Also, WSix step coverage for sub 0.5 μm polycide topographies were examined.
Titanium Carbide Films Deposited by Laser Reactive Ablation
Authors: Barucca G. , Leggieri G. , Luches A. , Majni G. , Mengucci P. 
Published: April 2011

ABSTRACTTitanium carbide films were deposited on silicon wafers by laser reactive ablation. A pure titanium target placed inside a methane (CH4) atmosphere was irradiated by a XeCl excimer laser with a fluence of 5 J/cm2 and a repetition rate of 8 Hz. Experiments were performed at different values of the ambient pressure in order to investigate the influence of the deposition parameters on the film properties. Results show that at low pressure values (p< 10-5 mbar) the deposited layers are mainly constituted of metallic titanium whereas for pressure ranging from 10-5 to 10-1 mbar they are formed of titanium carbide (TiC) with small amount of oxides. The stoichiometry and thickness of the titanium carbide films can be controlled by the partial pressure of the atmosphere and the number of laser pulses, respectively.
Interaction of Hyperthermal Hydrogen with the Diamond Surface
Authors: Haggerty David , Bandis Christos , Pate Bradford B. 
Published: April 2011

ABSTRACTA mass-selected low kinetic energy (1–50 eV) ion source is used to expose the diamond (111) surface to ionized atomic hydrogen (H+) at controlled impact kinetic energy. We report the result of 20 eV and 50 eV kinetic energy exposures as measured by ultraviolet photoelectron spectroscopy (UPS). UPS is found to be a useful probe of hydrogen adsorption on diamond.
Thermally Annealed GaN Nucleation Layers And The MOCVD Growth Of Si-Doped GaN Films On (00.1) Sapphire
Authors: Wickenden D. K. , Miragliotta J. A. , Bryden W. A. , Kistenmacher T. J. 
Published: April 2011

ABSTRACTThe effect of epitaxial growth temperature in the range 985 – 1050°C on the preparation of device quality Si-doped GaN layers on self-nucleated (00.1) sapphire has been explored. Not unexpectedly, several device-related properties monotonically improve with increasing growth temperature, including: (a) carrier density; and, (b) volume fraction of heteroepitaxial domains. However, a number of equally important device-related properties show a local maximum or minimum and include: (a) optical second-harmonic generation intensity; (b) structural coherence; and, particularly (c) surface morphology. The antecedents of the first class is found in an increase in surface and bulk diffusion and a reduction in film defect incorporation and stress at the GaN/GaN (nucleation layer)/α-Al2O3 heterointerface (even for overlays with thicknesses near 1 μm). The second class apparently stems from the limited range over which the thermally annealed GaN nucleation layer stimulates pseudo two-dimensional growth of the overlayer.
Recombination Processes of the Broadband And 1.681 Ev Optical Centers in Diamond Films
Authors: Bergman L. , Mcclure M. T. , Glass J. T. , Nemanich R. J. 
Published: April 2011

ABSTRACTMicro- and Macro-photoluminescence techniques were employed in this research to investigate the role of nitrogen-doping on the optical spectra of chemical vapor deposited diamond films and to determine whether the origin of the broadband luminescence is due to vibronic interaction of the nitrogen centers. The temperature behavior of the broadband PL and of the 1.681 eV silicon related optical center were analyzed. The intensity of the broadband was found to exhibit a temperature dependence characteristic of optical emission from a continuous distribution of gap states while the temperature dependence of the 1.681 eV band followed the Boltzmann quenching process.
Properties of the Heteroepitaxial AIN/SiC Interface
Authors: Benjamin M. C. , Wang C. , Kern R. S. , Davis R. F. , Nemanich R. J. 
Published: April 2011

ABSTRACTThis study presents the results of surface investigation of the heteroepitaxial AIN/SiC interface. The analytical tools employed included UPS, XPS, Auger spectroscopy, and LEED. The surface electronic states were characterized by uv photoemission obtained at surface normal. Conclusions drawn from this study are that the AIN/SiC structure results in a negative electron affinity surface which is extremely sensitive to defect density. The surface Fermi level is found to be near the middle of the AlN gap, and a possible band alignment between the AlN and SiC is presented.
Arsenic Incorporation in InP Epilayers and Arsenide/InP Heterostructures Grown by Chemical Beam Epitaxy
Authors: Rossignol V. , Bensaoula A. H. , Freundlich A. , Bensaoula A. , Neu G. 
Published: April 2011

ABSTRACTLow levels of arsenic contamination have been previously reported (∼0.01%) in CBE grown InP by different groups. The level of As incorporation in InP is usually enhanced when arsenide(InGaAs, InAsP) / InP heterostructures are grown.In this work, optimal growth conditions to minimize the non-intentional As contamination during the growth of these heterostructures are discussed. The red shift of band-edge excitons in the low temperature photoluminescence spectra as well as the analysis of high resolution X-ray diffraction patterns of InAsP/InP multi-quantum wells suggest the presence of As in InP barriers. This contamination is consistent with the ratio of As/P partial pressure (As residual in the chamber: 10-9-10-8 Torr) and the As/P incorporation rates. We have studied the influence of the growth temperature, the group-V/III flux ratio and the growth rate on the level of the As incorporation.
Properties of inxGa1-xAs Crystals Grown by Lpee on Patterned GaAs Substrates
Authors: Bryskiewicz T. , Jiran E. , Bryskiewicz B. , Buchanan M. 
Published: April 2011

ABSTRACTInxGa1-xAs crystals, 0 < x < 0.2, have been successfully grown by LPEE on the GaAs substrates which, prior to growth, were coated with SiO2 layer and patterned by photolithography. The ternary seeds originated in the oxide free seeding windows, 2 – 20 μm wide and 100 μm apart, extended over SiO2 coating and merged to result in a continuous, monocrystalline layer with no apparent trace of boundaries of the merging islands. A considerable improvement in structural perfection of the ternary crystals has been achieved: the FWHMs of the rocking curves and dislocation density was in the 30 –40 arc seconds and low 105cm−2 range, respectively. Structural perfection of InxGa1-xAs crystals grown on patterned GaAs substrates is far superior to that of the ternary buffer layers grown by MBE or MOCVD.
Plasma Effects on Thin Film Microstructure
Authors: Naeem Munir D. , Rossnagel Stephen M. , Rajan Krishna 
Published: April 2011

ABSTRACTWe have studied the effects of low energy ion bombardment on thin copper films. Evaporated, sputtered and CVD copper films (∼50 nm) were exposed to Magnetically Enhanced (ME) Ar plasmas. The microstructural changes (grain size) in the films were studied using Transmission Electron Microscopy (TEM).Grain growth is observed in thin Cu films when the films are exposed to low energy (87 eV) Ar plasmas. The microstructural changes in sputtered and evaporated films are quite significant whereas the plasma bombardment has less effect on CVD films. These changes occur very rapidly and cannot be attributed solely to the thermal effects, especially at low RF power levels (500 W). The initial microstructure of the film has a significant effect on grain growth during plasma exposure.
Chemical Stability of Reactively Sputtered AlN with Plasma Enhanced Chemical Vapor Deposited SiO2 and SiNx
Authors: Cho Jaeshin , Saha Naresh C. 
Published: April 2011

ABSTRACTWe have studied the chemical stability of reactively sputtered aluminum nitride film with plasma-enhanced chemical vapor deposited SiO2 and SiNx films. It was found that the PECVD SiO2 film reacted with A1N to form aluminosilicate (3Al2O3·2SiO2) at the SiO2/A1N interface after annealing above 550°C. The presence of Al-0 bonds at the SiO2/AlN interface was verified with x-ray photoelectron spectroscopy and x-ray induced Auger electron spectroscopy. The formation of aluminosilicate resulted in significant decrease in the wet etch rate of A1N layer. For SiNx/AlN/Si layered structure, no interfacial reactions were detected at the SiNx/AlN interface after annealing up to 850°C. These results confirm the thermodynamic predictions on the mutual stability of SiNx/AlN and SiO2/AlN.
Microstructure and Chemical Ordering in UHV-Deposited, Polycrystalline Coxpt1−x Alloy Films for Magneto-Optical Recording
Authors: Farrow R. F. C. , Weller D. , Toney M. F. , Rabedeau T. A. , Hurst J. E. , Harp G. R. , Marks R. F. , Geiss R. H. , Notarys H. 
Published: April 2011

ABSTRACTWe report magneto-optical recording with 62 dB CNR (carrier-to-noise ratio) at 488 nm for quadrilayer structures comprising polycrystalline CoxPt1-x (x = 0.28) alloy films deposited on ungrooved, silicon nitride -coated glass discs, held at 300°C, by UHV evaporation. The key parameter controlling magnetic anisotropy of the films is substrate temperature during deposition. Polycrystalline films grown on amorphous silicon nitride have a large coercivity and full perpendicular remanance when grown at 300°C. Synchrotron X-ray diffraction data for polycrystalline films grown at 300 and 600°C confirm the presence of short-range compositional order, to the CoPt3-L12 phase in both cases. Such ordering can introduce an anisotropy in the distribution of Co-Co pairs in the alloy and is a possible source of the magnetic anisotropy.
Magnetic and Magneto-Optical Properties of Sputter-Deposited and Annealed Co-Pt Alloys
Authors: Park Sung-Eon , Jung Pu-Young , Kim Ki-Bum , Lee Seh-Kwang , Kim Soon-Gwang 
Published: April 2011

ABSTRACTWe have produced Co1-xPtX (X = 0.53 and 0.75) alloy films using DC magnetron sputtering and investigated their magnetic properties using vibrating sample magnetometry(VSM) and Kerr hysteresis loop tracer. The as-deposited Co-Pt alloy films show a strong in-plane magnetization. By annealing the alloy samples, we have identified that the magnetic properties are drastically changed. While the magnetic properties of the Co0 25Pt0 75 alloy films show no noticeable changes, the coercivity and the squareness of the Co0.47Pt0.53 alloy films are drastically increased after annealing. Transmission electron microscopy(TEM) and x-ray diffractometry(XRD) analysis showed that CoPt(L10) and Co-Pt3 (L12) ordered phases, respectively, are formed in each case with a strong (11) texture. We suggest that the perpendicular magnetic anisotropy in the Co-Pt system does not depend on the mere textureness of the layer but strongly depends on the arrangement of Co and Pt at an atomic scale.
The Effect of Incident Kinetic Energy on Stress in Sputter-Deposited Refractory-Metal Thin Films
Authors: Vink T.J. , van Zon J.B.A.D. , Kools J.C.S. , Walrave W. 
Published: April 2011

ABSTRACTIn magnetron sputter deposition the intrinsic stress in refractory-metal films changes from compressive to tensile on increasing the working-gas pressure. This pressure dependence is linked to the particle transport process from target to substrate during deposition. In this work we apply a Monte Carlo (MC) technique to simulate the transport of sputtered atoms and reflected neutrals in a background gas. Specific examples of Cr, Mo and W thin film growth in Ar and Ne gas ambients are presented. Trends in thermalization of the depositing atoms coincided with the observed trends in the compressive-to-tensile stress curves, for the different target and working-gas combinations studied. Furthermore, a quantitative correlation between the stress transition pressures and the incident kinetic energy of both sputtered atoms and reflected neutrals during film growth was found. In this case the contribution of the latter species was weighted with a relatively low factor.
Polycrystalline Silicon Layers for Shallow Junction Formation: Phosphorus Diffusion from In Situ Spike-Doped Chemical Vapor Deposited Amorphous Silicon
Authors: Krüger D. , Schlote J. , Röpke W. , Kurps R. , Quick Ch. 
Published: April 2011

ABSTRACTShallow and lateral homogeneous delineated n+p-junctions were formed utilizing solid source diffusion from a deposited amorphous silicon layer with an in situ imbedded ultrathin phosphorus-rich zone. SIMS, AES, and TEM investigations were carried out to analyze the dopant behavior in correlation to morphological and structural changes during subsequent heat treatments. After heat treatments up to 950°C the layer remained flat, surface roughness was found to be less than 3 nm. Dopant pile up at the Si-layer/Si-substrate interface was observed and interpreted on the basis of segregation phenomena. From the time dependence the P segregation-pile-up was found to be diffusion limited except for a small starting period. The dopant concentration in the Si-substrate drops down over more than 2 orders of magnitude in a thickness range less than 20 nm.
Silicon Nitride Optimisation for a-Si:H TFTs Used in Projection LC-TVs
Authors: French I. D. , Curling C. J. , Goodyear A. L. 
Published: April 2011

AbstractMulti-layer devices based on thin films in Large Area Electronics have different intrinsic and extrinsic properties that must be optimised to produce the correct physical shape of the device, in addition to having acceptable electrical characteristics. For instance it is quite easyto produce individual layers optimised for electrical performance that will physically “pull off” underlying films, or result in poor step coverage. The factors that must be considered include mechanical stress, etching rates and profiles, thickness and stoichiometry uniformity, and thermal budgets, as well as electrical characteristics. This paper gives an example of silicon nitride optimisation for use in a-Si:H TFT projection displays. Three different silicon nitride layers were included to give a storage capacitor, together with controlled etch profiles for step coverage. The layers were optimised with respect to several different parameters in the minimum number of depositions by the use of experimental design techniques.
Rapid Thermal Crystallization Of LPCVD Amorphous Silicon Films
Authors: Voutsas A. T. , Hatalis M. K. , Olasupo K. R. , Nanda A. K. , Alugbin D. 
Published: April 2011

AbstractThe crystallization of LPCVD a-Si by Rapid Thermal Anneal was investigated. RTA polysilicon films can find application in the fabrication of TFTs for AMLCDs, due to the lower thermal budget associated with fast crystallization at high temperatures. It was found that the grain size of the crystallized films decreases with the temperature, in the range of 700°C to 1100°C, while for higher temperatures the opposite trend is observed. The latter observation was attributed to the high thermal vibration of subcritical clusters, that was assumed responsible for the decline in the nuclei population at high annealing temperatures, combined with the faster crystalline growth rate at high temperatures. RTA silicon films were found to have lower intra-grain defect density, that may result in the improvement of the electrical characteristics of the polysilicon films.
Non-Invasive Measurement of Subcutaneous Fat Thickness in Beef Cattle
Authors: Taylor Leonard S. , Buck Nelson L. 
Published: April 2011

ABSTRACTThe object of this project was the evaluation of microwaves as a non-invasive tool for determining the thicknesses of the fat layers directly beneath the hides of beef cattle. The motive for the project is the elimination of the cost of feeding cattle beyond the point at which the muscle is optimally marbled. The nature of the animals and the conditions for operation require a simple, rugged, non-invasive system. Modified open-ended microwave S-band coaxial cavities were applied as contact radiators to the surface of a three-layer sample composed of lean meat and fat tissue, which simulated the configuration of hide, fat and muscle on the outside of an animal. The lean and fat layers loaded the cavity, affecting the resonance frequency, bandwidth, and center-frequency reflection coefficient. Measurements were made with a network analyzer. An exact analysis of the microwave circuit has not been possible, but the in vitro laboratory tests show that a system based on this device can be used to measure subcutaneous fat layer thicknesses up to 16 mm beneath hides up to 16 mm thick.
Microwave Characterization of Materials Using a Vector Network Analyzer
Authors: Blackham David , Pollard Roger 
Published: April 2011

ABSTRACTThe vector network analyzer provides a versatile tool for use in the microwave characterization of material permittivity and/or permeability. An understanding of network analyzer error sources can be leveraged into better measurement results. Vector error correction not only reduces the systematic errors but can also be used to remove the effects of dielectric dams in broadband transmission/reflection measurements.
High Temperature Dielectric Property Measurements - An Insight into Microwave Loss Mechanisms in Engineering Ceramics
Authors: Binnen J. G. P. , Cross T. E. , Greenacre N. R. , Naser-Moghadasi M. 
Published: April 2011

ABSTRACTIt is now possible, in a number of laboratories worldwide, to make microwave dielectric property measurements at temperatures up to about 1500°C. These measurements have shown that the loss tangent, tanδ, of a wide range of engineering ceramics increases dramatically at elevated temperatures. The interaction between the ceramic material and the impurities present during processing can have a dramatic effect on both the ease with which the material is able to extract energy from the microwave field and on the properties of the final ceramic. While the effect of impurities on the ceramic properties is relatively well understood the effect of impurities on the microwave loss mechanisms at elevated temperatures is not. This paper will review some of the recent work on the high temperature microwave dielectric property measurements performed at Nottingham.
Numerical Models for the Sintering of Ceramics in a Multi-Mode Cavity
Authors: Dibben David C. , Fu Wai B. , Axas Ricky A.C. Met 
Published: April 2011

ABSTRACTWe present two distinct approaches to the numerical determination of electromagnetic field intensities which must be known before the sintering of ceramics can be modelled in a multi-mode microwave cavity. In the first, a Finite Element Method, we employ edge elements to discretise Maxwell's Equations and apply the conjugate gradient algorithm to solve the resulting system of linear algebraic equations at each time step. The second, which is based on the Method of Lines, is a variant of the Finite Difference Time Domain technique and is used to transform Maxwell's Equations into a set of time-dependent ordinary differential equations. These methods are compared with the help of three examples: a small tray of mashed potatoes placed inside a cavity, a standard waveguide partially filled with a ceramic, and a cavity inhomogeneously loaded with the same material. The good agreements which we have found give us confidence in the soundness of either approach for use in numerical simulation work.
Calculation of Heating Patterns in Microwave Sintering using a 3D Finite-Difference Code
Authors: Tucker James , Iskander Magdy F. , Huang Zhenlong 
Published: April 2011

ABSTRACTAnalysis of heating patterns in microwave sintering experiments provide information on the contributions of the various heat transfer components to the overall temperature pattern. Measured temperature patterns provide limited information on overall effects. Numerical simulations provide a cost effective way from which the effect of geometry, material properties and the presence of stimulus such as SiC rods or sheets on the heating pattern can be studied separately. Parametric studies allow us to identify the most significant properties and provide guidelines for the routine successful utilization of microwave sintering experiments. These guidelines may also facilitate the scale up and commercialization of microwave sintering.In this paper we describe a thermal model that calculates the temperature distribution in ceramic samples and insulation under realistic microwave sintering conditions. The calculation process involves a two-step procedure. The first step is to calculate the microwave power deposition in the sample and surrounding insulation. 3D FDTD calculations, described in a companion paper[1,2], are used for this purpose. The other step involves calculation of the temperature distribution using a 3D finite-difference heat-transfer program developed in our Departments[3]. Results illustrating the effect of thickness of insulation and the placement of SiC rod susceptors in picket-fence arrangement are presented.
First Results on Large Cerium Fluoride Crystals in A Test Beam
Authors: Auffray E. , Beckers T. , Chipaux R. , Dafinei I. , Depasse P. , El Mamouni H. , Faure J.L. , Fay J. , Hillemanns H. , Ille B. , Lebrun P. , Lecoq P. , Nelissen J. , Nikl M. , Raghavan R. , Rosowsky A. , Schneegans M. 
Published: April 2011

ABSTRACTCerium Fluoride, a new, dense, fast and radiation hard scintillator, is at present the favored candidate for high-resolution calorimetry at future colliders. This crystal has been extensively studied – in particular by the Crystal Clear Collaboration – and the conditions for production of large, high-quality crystals are now being optimized in seven firms all over the world. Recently the collaboration has received several CeF3 crystals, up to 17cm long, from three companies. A small assembly of such crystals with silicon photodiode readout was exposed to high energy electrons and muons in the H2-beam of the SPS at CERN. The results of these tests with longitudinally segmented towers are presented and discussed, in particular in terms of light yield and energy resolution.