bluuebunny/crossref_metadata_2025_split huggingface dataset:
Metastable Defect at Si-SiO2 Interfaces
Authors: Jing Z. , Lucovsky G. , Whitten J. L. 
Published: April 2011

AbstractAn important issue in semiconductor device operation is the rate at which current or voltage stress creates defects that degrade eventually device operation. Based on recent results on nitrided gate dielectrics, we have concluded that bonded-H at the Si-SiO2 interface plays a role in the formation of metastable defects that can be activated, and subsequently neutralized, by sequential trapping of injected holes and electrons. In this paper, differences in defect behavior for Si-SiO2 interfaces that have exposed to nitrogen (N-) atoms or N-H groups are discussed. Based on these results, a microscopic model for interfacial defects is proposed.
DX-Like Centers in IV-VI.
Authors: Khokhlov Dmitriy R. 
Published: April 2011

AbstractUp to the recent times it was believed that observation of the DX-centers is restricted to the rather wide-bandgap III-V and II-VI semiconductors. However it becomes obvious now that some of the narrow-gap IV-VI semiconductors doped with the group III elements reveal the features of DX-centers. A range of features, such as negative-U behavior, large lattice relaxation, metastability of the local excited states, narrow bandgap - make the effects resulting from the DX-like behavior much more complicated than in the “classical” materials with the DX-centers. We review the most unusual recent results obtained in the field that originate from the specifics of the DX-like centers in IV-VI.
Are the Models of the Triply Charged Gallium Vacancy and Doubly Charged Gallium Interstitial Alive or Dead?
Authors: Cohen R. M. , Chen C. Y. , Li W. M. , Simons D. S. , Chi P. H. 
Published: April 2011

AbstractWe have found that the measured diffusivity can be quite different than predicted by recent models of multiply-charged defects. Key problems dealing with the measurement and the interpretation of diffusion mechanisms are discussed. Using a few common variations in GaAs epilayer growth, we have obtained diffusivities which range over several orders of magnitude at the same temperature. Making use of the relatively weak In-As bond, we have used In as a marker to measure group III interdiffusion, DIII. DIII is consistent with the results of others using Al as a marker in n-type GaAs, but orders of magnitude smaller than predicted by the triply charged Ga vacancy, V3−Ga, model of Tan and Gosele. Although diffusion can be attributed to a negatively charged vacancy in n-type GaAs, In is found to often move by a kick-out mechanism in p-type GaAs. It appears likely that many early experiments with n- and p-type GaAs-AlAs interdiffusion were affected by large concentrations of Ga interstitials, IGa, caused by Fermi energy pinning at the growing surface. We present the first direct experimental evidence for the existence of a positively charged Ga interstitial. Our results, combined with those of others, suggest that VGa has a single negative charge associated with it. Because epilayer growth conditions appear to cause the point defect concentrations to deviate substantially from equilibrium, we conclude that the exact charge states of VGa and IGa still remain to be determined.
Epitaxial Growth OF (001)- and (111)-Oriented PTMNSB Films and Multilayers
Authors: Kautzky M.C. , Clemens B.M. 
Published: April 2011

ABSTRACTIn this paper we report the successful growth of single-phase epitaxial PtMnSb films and multilayers by dc magnetron cosputtering, both in the (001) orientation on MgO(001) and W(001), and in the (111) orientation on Al2O3 (0001). Single-layer films in the thickness range 50Å≤t≤1000Å were grown and characterized using x-ray diffraction (XRD), magneto-optic Kerr effect (MOKE), and vibrating sample magnetometry (VSM). The in-plane orientation relationships, as determined by asymmetric XRD, were PtMnSb[100]∥MgO[110], PtMnSb[100]∥W[100], and PtMnSb[101∥Al2O3[2110]. The crystalline quality of the films was found to depend strongly upon the substrate, growth temperature, film thickness, and presence of a capping layer, but rocking curve widths of 1° or less were achieved on each substrate. Measurement of the in-plane strain showed that the films were almost entirely relaxed, with strains <1%. In-plane magnetization was observed in all cases, with moments and coercivities in the 400-500 emu/cm3 and 100-200 Oe ranges respectively. Polar Kerr spectra showed large rotations (0.75° - 1.03°), whose peak wavelengths appear to depend on both film structure and optical interference effects.
Universal mB/T Scaling of the Giant Magnetoresistance in Cu-Co Granular Ribbons Produced by Controlled Melt-Spinning
Authors: Madurga Vicente , Ortega R.J. , Vergara J. , Elvira R. , Korenivski V. , Rao K.V. 
Published: April 2011

ABSTRACTStudies of the evolution of electrical resistance in an external applied magnetic field, B, as well as with temperature, T, on Cu86Co14 and Cu92Co8 as quenched and annealed melt-spun ribbons, reveal that magnetoresistance, MR, ΔR(B,T)=R(B)-R(0) scales with B/T. Furthermore, it found that annealing up to 600 °C scales the magnetic moment of the Co-rich superparamagnetic nanoparticles such that, the data for the field dependence of the MR obtained at various temperatures collapses onto the same unique and universal curve f(mB/T) with the Langevin variable mB/T governing the overall behaviour.
Environmental Effects on Interface Behavior in Graphite / Epoxy Single Fiber Composites
Authors: Schadler Linda S. , Koczak Michael J. , Amer Maher S. 
Published: April 2011

ABSTRACTToray M40 graphite fiber / Epon 828 epoxy resin single fiber composites with both sized and unsized fibers were exposed to distilled water at 50°C and 100°C, 10% NaOH and HCl aqueous solutions at 50°C, and air at 100°C. Micro Raman spectroscopy was used to measure the strain and interfacial shear stress profiles as a function of environmental exposure. It was found that the degradation mechanism is primarily a mechanical failure of the fiber/matrix interface.
Tailoring the Structure of Polymer Brushes Through Copolymer Architecture
Authors: Gersappe Dilip , Fasolka Michael , Israels Rafel , Balazs Anna C. 
Published: April 2011

ABSTRACTPolymers tethered by one end onto a solid surface are referred to as polymer “brushes”. We consider brushes composed of copolymers that contain both A and B monomers. The A monomers are compatible with the surrounding solvent, while the B sites are solventincompatible. The solvent incompatibility causes the B sites to associate into domains or clusters within the layer. We use Monte Carlo computer simulations and self-consistent field calculations to determine the effect of copolymer architecture on the structure of the polymer brush. In particular, we alter the copolymer sequence distribution (the arrangement of the A and B monomers along the length of the chain) and determine how both the vertical and lateral morphology of the brush are effected by these variations. The results provide guidelines for controlling the size and shape of the B domains, and consequently, the morphology of the tethered layer.
Natural Poly(Hydroxybutyrate-Hydroxyvalerate) Polymers as Degradable Biomaterials
Authors: Chaput Cyril , Yahia L'Hocine , Selmani Amine , Rivard Charles-Hilaire 
Published: April 2011

ABSTRACTPoly(ß-hydroxybutyrate-co-ß-hydroxyvalerate) have been recently proposed as degradable biomaterials for drug delivery systems, sutures, bone plates and short-term implants. Three PIBF\HV (7, 14 & 22 % HV) films were analyzed for in vitro cytotoxicity and aqueous accelerated degradation, in vivo degradation and tissue reactions. The PHB/HV materials and extracts elicit few or mild toxic responses, do not lead in vivo to tissue necrosis or abscess formation, but provoke acute inflammatory reactions slightly decreasing with the time. The degradation of PHB/HV polymers present low rates in vitro as well as in vivo. The weight loss rate generally increases with the copolymer composition (HV content) and ranges from 0.15–0.30 (in vitro) to 0.25 %day (in vivo). Compositional and physico-chemical changes in PHB/HV materials were rapidly detected during the accelerated hydrolysis, but were much slower to appear in vivo. The structural and mechanical integrity of PHB/HV materials tend to disappear early in vitro as well as in vivo. After 90 wks in dorsal muscular tissues of adult sheep, there was no significant dissolution of the PHBiIV polymer, 50–60% of the initial weight still remaining. PHB/HV polymers are biodegradable materials, either by hydrolysis or implantation, but with extremely low dissolution or degradation rates.
Adhesion and Thermal Deformation of Ceramic/ Polymer Heterostructures
Authors: Madras Cynthia , Wong Peter Y. , Miaoulis Ioannis N. 
Published: April 2011

ABSTRACTThe adhesion and thermal properties of optical ceramic structures bonded by a polymer interlayer are explored. The mechanical, adhesion and optical properties of the heterostructure are dependent on the thickness of the bond and on the residual thermal stresses developed during the bonding process. The thermomechanical properties of a bonded structure over a range of temperatures are investigated, focusing on the thermal expansion and operating temperature limits of the polymer bond. The temperature and stress histories during manufacturing are determined through both numerical modeling and experimental analysis. The effect of stress relaxation and initial stresses on the behavior of the bonding material are examined for different processing conditions. The bond material relaxation time constant, activation energy, viscosity, and shear modulus are approximated from observation of the temperature-dependent behavior of the structure.
Direct Surface Analysis of Organic Contamination for Semiconductor Related Materials
Authors: Lee J. , Odom R. W. , Strossman G. S. , Lindley P. M. 
Published: April 2011

ABSTRACTDirect surface analysis of Si wafers and environmental materials such as polymers for wafer carriers and for high purity water systems is important to identify contaminants and their sources. Organic contaminants on the surfaces are difficult to analyze; however, their adverse effects have been cited in recent years. This paper demonstrates the detection and identification of surface contaminants using Time-of-Flight Secondary Ion Mass Spectrometry (TOF-SIMS) on semiconductor related materials. The analytical information provided by TOF-SIMS can be useful for maintaining material cleanliness or for failure analysis.
Outplating of Metallic Contaminants on Silicon Wafers From Diluted Acid Solutions
Authors: Rotondaro A. L. P. , Hurd T. Q. , Schmidt H. F. , Teerlinck I. , Heyns M. M. , Claeys C. 
Published: April 2011

ABSTRACTThe outplating behaviour of Fe and Cu was investigated for diluted solutions of HCl and HNO3. The deposition of the metallic contaminants was found to be strongly dependent on the type of surface that is exposed to the contaminated solution. Cu deposits heavily on bare silicon surfaces, whereas only low levels of Fe deposition are observed. On the other hand, on thermal oxide surfaces, the levels of deposited Fe are consistently higher than the Cu ones. The acid used appears to have no major impact on the deposition process. The pH of the solutions has a major effect on the Cu deposition and a minor effect on the Fe case.
Correlation of Roughness and Device Properties for Hydrogen Plasma Cleaning of Si(100) Prior to Gate Oxidation
Authors: Montgomery J. S. , Barnak J. P. , Silvestre C. , Hauser J. R. , Nemanich R. J. 
Published: April 2011

ABSTRACTHydrogen plasma treatment was used as a cleaning and conditioning step prior to gate oxide deposition in the fabrication of cluster-based MOS field effect transistors. Surface roughness was measured by atomic force microscopy and compared to current-voltage characteristics of the MOSFET devices. The MOSFET devices were evaluated on the basis of threshold voltage, peak mobility, interface scattering, and surface roughness coefficient. Following a 10 minute Hplasma exposure at a substrate temperature of 150°C the rms roughness increased from 1.1±0.3 Å to 17±9 Å. The rms roughness for samples treated for 10 minutes at 700°C was 4±1 Å. Analysis of the MOSFET devices treated in the low temperature range (200°C) show significant degradation due to the H-plasma interaction. Threshold voltage for the devices exposed to a 2 minute H-plasma at a temperature of 200°C was 0.72±0.02 V. In contrast the threshold voltage for the 600°C, 2 minute plasma exposure was 0.86±0.03 V. The peak mobility for those devices was 370 cm2/V-s. Further device analysis was accomplished from the current-voltage measurements to extract a value of interface scattering and surface roughness scattering for each device. Interface scattering and surface roughness scattering do not increase for H-plasma process temperatures of 450 – 700°C. An H-plasma treatment for 2 minutes at 500°C also resulted in no observable increase in rms roughness, a threshold voltage of 0.92±0.03 V, a peak mobility of 410 cm2/V-s, and no increase in interface scattering and surface roughness scattering.
In Situ Auger Spectroscopy Investigation of InP Surfaces Treated in RF Hydrogen and Hydrogen/Methane/Argon Plasmas
Authors: Parmeter J. E. , Shul R. J. , Miller P. A. 
Published: April 2011

ABSTRACTWe have used in situ Auger spectroscopic analysis to investigate the composition of InP surfaces cleaned in rf H2 plasmas and etched in rf H2/CH4/Ar plasmas. In general agreement with previous results, hydrogen plasma treatment is found to remove surface carbon and oxygen impurities but also leads to substantial surface phosphorus depletion if not carefully controlled. Low plasma exposure times and rf power settings minimize both phosphorus depletion and surface roughening. Surfaces etched in H2/CH4/Ar plasmas can show severe phosphorus depletion in high density plasmas leading to etch rates of ∼ 700 Å/min, but this effect is greatly reduced in lower density plasmas that produce etch rates of 30–400 Å/min.
Preferential Etching of Si(111) and Si(001) in Dilute NH4F Solutions: as Probed by In Situ STM
Authors: Itaya Kingo , Yau Shueh-Lin , Kaji Kazutoshi 
Published: April 2011

ABSTRACTIn situ scanning tunneling microscopy (STM) was used to examine the etching process of n-Si(11) and Si(001) electrodes in dilute NH4F under cathodic potential control. For Si(111), time-dependent STM images have revealed the pronounced effect of the microscopic structure of surface Si atoms on their dissolution rates. The multiple hydrogen bonded Si atoms at the kink sites and dihydride steps eroded faster than the monohydride terminated Si. Presumably, the higher polarity at these defect sites is responsible for the difference. Steric consideration further favors the higher activity at the more open kink sites. The monohydride terminated Si(111) surface represents the most stable surface structure, which guides the dissolution of the Si(001) surface to the formation of {111} facets. The initial stage {111} facet formation on a Si(001) surface was revealed by in situ STM.
Characterization of Defects Produced in TEOS Thin Films due to Chemical-Mechanical Polishing (CMP)
Authors: Kaufman F. B. , Cohen S. A. , Jaso M. A. 
Published: April 2011

ABSTRACTTime zero breakdown electrical measurements, SIMS, Bias Temperature Stress (BTS), and Triangular Voltage Sweep (TVS) techniques performed on MOS capacitors have been used to characterize two types of defects produced in TEOS thin films subjected to CMP process planarization. Microcracking of the insulator, resulting in degradation in breakdown characteristics, and uptake of K+ions (from the polishing slurry) are found to occur. These defects are thought to be caused by the chemical and mechanical stress to which the oxide surface is subjected during the CMP process. The effects of polish pad type, non K+ion containing slurry and post-CMP wet etch steps were all found to influence the extent of damage observed in polished films.
Modeling and Simulation of Pulsed Laser annealing and ablation of Solid Materials
Authors: Liu C. L. , Wood R. F. 
Published: April 2011

AbstractSeveral different aspects of laser annealing and laser ablation have indicated the need for two-dimensional (2-D) modeling of heat transfer and phase-change effects. We have in mind particularly the laser-induced formation and propagation of buried liquid layers for the case of a-Si on a crystalline silicon substrate, questions related to the early stages of the laser ablation of insulators such as MgO where it is believed that the absorption of the laser radiation occurs at localized but extended regions of high concentrations of defects, and the ejection of particulate material during laser ablation. To deal with these phenomena, a 1-D computational model originally developed for laser annealing has been extended to two-dimensions. the 2-D modeling examines the heat flow and phase changes associated with localized heat sources embedded in a planar material. Concepts such as the state diagram and state array used in the 1-D work have been extended to 2-D and refined. the 2-D program has been rewritten for massively parallel machines such as the intel Paragons in ORNL's Center for Computational Sciences, thus allowing larger and more accurate calculations for complex systems to be carried out in reasonable times.
Amorphous Diamond-Like Carbon Film Growth by KrF-and Arf-Excimer Laser Pld: Correlation with Plume Properties
Authors: Puretzky A. A. , Geohegan D. B. , Jellison G. E. , Mcgibbon M. M. 
Published: April 2011

AbstractA comparative study of arF- and KrF-laser deposition of amorphous diamond-like carbon (DLC) films and relevant carbon plasmas has been performed. Spectroscopic ellipsometry and EELS analysis of the DLC films deposited on Si <100> and NaCl substrates were utilized to characterize the high quality arF- and KrF-laser deposited films (up to 84% of sp3 bonded carbon in 7 J/cm2 -ArF-laser DLC film). Gated ICCD imaging, luminescence and ion current probe diagnostics of the carbon plume have revealed quite different properties of carbon plasmas generated by arF- and KrF- lasers. KrF-laser (6.7 J/cm2) irradiation produces a less energetic carbon plasma containing larger amounts of C2 and probably larger clusters compared with arF-laser irradiation at the same energy fluence. We conclude that the more energetic and highly-atomized arF-laser carbon plasma results in the better diamond-like properties.
Ion Beam Deposition of Boron-Aluminum Nitride Thin Films
Authors: Edgar J.H. , Eddy C.R. , Sprague J.A. , Sartwell B.D. 
Published: April 2011

AbstractAnalysis of the phase behavior, structure, and composition of aluminum nitride thin films with up to 22% boron prepared by ion-beam assisted deposition is presented. the c-lattice constant of the film decreased with increasing boron content as expected from the formation of an aIN - wurtzite BN alloy. there was no evidence for separate boron nitride precipitation from either X-ray diffraction or FTIR. IN contrast, auger electron spectroscopy of the boron present in the films suggested that two types of boron bonding was present.
Dissociative Chemisorption at Hyperthermal Energies: Benchmark Studies in Group IV Systems
Authors: Xia L.-Q. , Jones M. E. , Maity N. , Roadman S. E. , Engstrom† J. R. 
Published: April 2011

AbstractWe present a review of our recent work concerning supersonic molecular beam scattering of thin film precursors from the Si(100) and Si(111) surfaces. Both SiH4 and Si2H6 exhibit translationally activated dissociation channels at sufficiently high incident kinetic energies, (E┴) 0.5 eV. the dominant variables under our reaction conditions are the incident kinetic energy and the angle of incidence, whereas mean internal energy and substrate temperature play relatively minor roles. the former two variables couple to produce a universal relationship between the reaction probability and a scaled kinetic energy given by (E┴) = Eі[(l-Δ)cos2θі + 3Δsin2θі], where θі is the angle of incidence, a is a corrugation parameter, and 0 ≤ Δ ≤ 1. IN addition to the reaction probability, the reaction mechanism for Si2H6 is also dependent upon incident kinetic energy and surface structure, where a SiH4(g) production channel is observed on the Si(111)-(7x7) surface at low to moderate incident kinetic energies. the reactions of SiH3CH3 and PH3 provide convenient comparative examples. Methylsilane, reacting on a β-SiC surface, exhibits a translationally activated dissociation channel, similar to what is observed for SiH4 and Si2H6. Phosphine, on the other hand, exhibits the characteristics of trapping, precursor-mediated dissociative chemisorption. these results act to underscore the important role played by the frontier orbital topology, even at hyperthermal incident kinetic energies.
Effects of Carbon-Ion Irradiation-Energies on the Molecular Beam Epitaxy of GaAs and Ingaas
Authors: Makita Y. , Iida T. , Shima T. , Kimura S. , Obara A. , Harada K. , Tu C.W. , Uekusa S. , Matsumori T. , Kudo K. , Tanaka K. 
Published: April 2011

AbstractCarbon ion (C+) irradiation during molecular beam epitaxy (MBE) growth of GaAs/GaAs and in0.53.Ga0.47As/InP layers was carried out using CIBMBE (combined ion beam and molecular beam epitaxy) method as a function of wide acceleration energy (Ea=30 eV-30 keV) at a constant ion beam current density. Judging from the monitored current density and the net hole concentration (INA-ND|) obtained from Hall effect measurements, activation rate as high as 88% was achieved for as-grown GaAs layers by C+ ion irradiation of Ea=~170eV. It was revealed that by annealing at 800°C, a slight enhancement (~ 10%) of INA-ND| is practiced for Ea <~ 130eV but a significant increase of INA-ND| is realized for Ea>~lkeV. IN in0.53Ga0.47As/InP layers with increasing Ea, a type conversion of electric conduction from n to p was found to occur at Ea= ~70~100eV. these observations describe that Ea plays a vital role to determine the location of incorporated electrical and optical active impurities in GaAs and inGaAs. Further for comparison, C+-implanted GaAs layers were prepared by high-energy (400 keV) ion-implantation as a function of substrate temperature (T1=RT-600 °C). For C dose concentration of lxl018cm-3\ the highest activation rate of ~20 % was obtained at T1=~150 °C. This result states that CIBMBE method is a superior doping method in view of activation rate of introduced dopants and the formation of damage-free ion-irradiated layers.
Velocity Selection of Laser Ablated Metal Atoms by a Novel Non-Mechanical Technique
Authors: Fajardo Mario E. , Macler Michel 
Published: April 2011

AbstractWe present the results of experiments on velocity selection of fast laser ablated al, Ga, and in atoms by a novel, non-mechanical, technique. Pulses of atoms with broad velocity distributions are produced by laser ablation of a single component pure metal target in vacuum. after a delay of ~ 1 μs, there exists a strong one-to-one correlation between atomic velocity and distance traveled from the ablated surface. Thus, a second pulsed laser, delayed by ~ 1 μs and crossed at a right angle to the atomic beam, can be used to photoionize only those atoms with unwanted velocities, i.e.: atoms moving too fast or too slow to be hidden behind an opaque mask placed ~ 1 cm from the ablated surface. the photoions, and any ions surviving from the ablation event, are subsequently deflected from the beam by a static magnetic field. by a fortunate coincidence, al, Ga, and in atoms all have very large single photon photoionization cross sections at 193 nm, the output wavelength of the arF excimer laser; thus, well over 95% of the unwanted atoms can be easily photoionized and rejected. We have demonstrated velocity selected al, Ga, and in atom fluxes equivalent to Ф ~ 1011 atoms/(cm2-eV-pulse) at a working distance of 10 cm.