bluuebunny/crossref_metadata_2025_split huggingface dataset:
The Electronic Micro Structure in the Implant Layer of Ion Implanted Polymers
Authors: Giedd R.E. , Robey D. , Wang Y.Q. , Moss M. G. , Kaufmann J. 
Published: March 2011

ABSTRACTThe mechanical and electronic properties of ion implanted polymers have been determined to be a function of ion dose, energy and beam current. In previous studies the implant layer was assumed to be isotropic. In an earlier report we speculated that the implant layer was not isotropic, based on a temperature coefficient of resistivity (TCR) that could not be explained by a single structural configuration[1]. In this study we examined the effect of etching the surface layer, decreasing polymer thickness, on the TCR to determine which part of the implant layer contributed to the various mechanisms of conduction. We have concluded that there are at least two mechanisms responsible for conduction, Mott three dimensional variable range hopping(VRH), and Mott one dimensional VRH. It is possible that other theories may be more correct (e.g. crossover to ES-VRH at low temperatures) since many theories predict the same temperature dependence. We found that conduction with the Mott one dimensional VRH exists at the bottom of the implant layer.
Formation of SiGe and SiGeC Layers on Si by Ge and C Ion Implantation and Subsequent Ion-Beam-Induced Epitaxial Crystallization
Authors: Kobayashi Naoto , Hasegawa Masataka , Phillips J.R. , Hayashi Nobuyuki , Tanoue Hisao , Shibata Hajime , Makita Yunosuke 
Published: March 2011

ABSTRACTFabrication of Si1-xGex and Si-1-x-yGexCy layers on Si(100) by high-dose ion implantation of 72Ge ions without and with 12C ions and subsequent high-energy and low-energy ion-beam-induced epitaxial crystallization (IBIEC) has been investigated. Structural properties of the surface layers were observed by RBS-channeling technique. Si(100) wafers were implanted with 150keV and 80keV Ge ions at room temperature so as to produce a peak concentration of Ge amounting to approximately 2 and 14 at.%, respectively. C ions were additionally implanted to a fluence of 10% of Ge concentration for the SiGeC samples. IBΓEC experiments performed with 400keV 18Ar ion bombardments have induced crystallization of the amorphous layers of SiGe and SiGeC on Si up to the surface at 400°C for both samples with low Ge concentration (2%) and high Ge concentration (14%). IBIEC using 72Ge ions with energies whose projected ranges are within the amorphous layer was alternatively performed for SiGe layer on Si. Bombardments of 140keV and 40keV Ge ions at 400°C have induced crystallization up to the surface with a slight disorder in the grown layer. Present experimental results suggest a novel ion beam synthesis method of fabrication of SiGe (SiGeC) on Si at low temperatures.
Ion Implantation of Ti,Mo W,Mo+C and W+C in H13 Steel and Aluminum at Elevated Temperature
Authors: Tonghe Zhang , Fuzhong Wei , Jun Chen , huixing Zhang , Xioji Zhang , Ting Lu 
Published: March 2011

ABSTRACTThe chemical change in the surface of H13 steel or aluminum is produced by implanting a reactive elements, such as Ti, Mo and W. The X-ray diffraction pattern shows that implanted Ti at 400 C has reacted with carbon(0.35 in wt.%) forming a second phase TiC. Auger analysis shows that the carbon atoms have been condensed in the Ti implanted region. Carbon peak concentration of 30 At.% is greater than Ti atom peak concentration of 12 At.%.Several second phases are formed during pulsed Mo ion implantation 2 into aluminum with high ion flux of 50˜80µA/cm2 which raises the target temperature from 400°C to 600°C.More second phases are formed by dual Mo+C implantation with high dose of 3˜5×10 17/cm2 and high flux of 50˜75µA/cm2 . And the target temperature is raised from 400 to 600°C. The FeMo Fe3Mo2, Fe2MoC, Mo2C, MoC, MoCx, phases and iron carbides are identified by X-ray diffraction technique.
Oxide Formation on NbAl3, and TiAl Due to Ion Implantation of 18O
Authors: Hanrahan Robert J. , Verink Ellis D. , Withrow Stephen P. , Ristolainen Eero O. 
Published: March 2011

ABSTRACTSurface modification by ion implantation of 18O ions was investigated as a technique for altering the high-temperature oxidation of aluminide intermetallic compounds and related alloys. Specimens of NbAl3 and TiAl were implanted to a dose of 1×1018 ions/cm2 at 168 keV. Doses and accelerating energies were calculated to obtain near-stoichiometric concentrations of oxygen. Use of 18O allowed the implanted oxygen profiles to be measured using secondary ion mass spectroscopy (SIMS). The near surface oxides formed were studied using x-ray photoelectron spectroscopy (XPS) and Auger electron spectroscopy. Specimens were also examined using x-ray diffraction and SEM. This paper presents results for specimens examined in the as-implanted state. The oxide formed due to implantation is a layer containing a mixture of Nb or Ti and amorphous Al oxides.
Evolution of Defect and Impurity Profile During High Dose Co Implantation into Si at Elevated Temperatures
Authors: Schippel S. , Witzmann A. 
Published: March 2011

ABSTRACTȥ111Ɂ -Si was implanted with 250 keV Co ions at a target temperature of 350°C. The ion dose was varied between 1×1014 cm-2 and 2×1017 cm-2 . The evolution of the defect and impurity profile was investigated by Rutherford Backscattering Spectrometry (RBS), channeling and transmission electron microscopy (TEM).Up to a dose of 1 × 1015 Co cm-2 no defects can be detected. At higher Co doses, we find correlated defects in the center of the Co distribution and point defects in the region below. Moreover, damage accumulation at the surface is observed. The concentration of defects increases with increasing ion dose and reaches its level of saturation at a dose of 2 × 1016 cm-2.The Co profiles of samples implanted at 350°C differ considerably from the Gaussian shape. The near surface and the back flank are parts of Gaussian distributions. However, the standard deviation of the near surface flank is always smaller than that of the back flank. Moreover, the distributions show tails into the substrate at depths > 320 nm. This proves that radiation damage acts as an effective center for the nucleation of CoSi2.During annealing we find a redistribution of Co towards the defective regions for Co doses between 1 × 1016 cm-2 and 5× 1016 cm-2.
Metal Vapour Vacuum Arc Ion Source to Synthesize Refractory Metal Silicides
Authors: Liu B.X. , Zhu D.H. , Lu H.B. , Tao K. 
Published: March 2011

ABSTRACTMetal Vapour Vacuum Arc (MEWA) Ion Source was employed, for the first time, to synthesize metal suicides. Refractory metal suicides NbSi2, TaSi2, WSi2 and MoSi2 were successfully formed by implanting respective metal ions into Si(111) wafers. It was found that the high current density metal ion implantation not only provided the metal components but also caused a simultaneous annealing for various metal-suicide phases to grow. When the impLantation was conducted at 40 kV, the Nb ion current density was up to 76 µA/cm2 at a dose of 4x1017/cm 2, and the Ta, W and Mo ion current densities were up to 65 µA/cm2 at a dose of 5×1017 ions/cm2 , hexagonal NbSi2, TaSi2, MoSi2 and WSi2 were formed. Post annealing transformed the WSi2 and MoSi2 phases from hexagonal to tetragonal structure, featuring lower resistance than that of the as-implanted ones.
Characterization of Ion Beam Synthesized Materials Using Microscope-Spectrophotometry
Authors: Geatches Rachel M. , Reeson Karen J. , Criddle Alan J. , Finney Mark S. , Harry Milton A. , Webb Roger P. , Pearson Peter J. 
Published: March 2011

ABSTRACTIn this paper, the technique of microscope-spectrophotometry, used to nondestructively characterize the microstructure of ion beam synthesized iron-disilicide layers, is described. The results obtained agree extremely well, in terms of layer thickness and interfacial roughness, with those from Rutherford backscattering. The results also show that it is possible to interpret the measured spectral reflectance data in terms of: 1) defect annealing; 2) iron redistribution; and 3) phase transformations from the β to the α phase.
Is Self-Organisation During Ostwald Ripening a Crucial Process in Ion Beam Synthesis ?
Authors: Reiss S. , Heinig K.-H. , Weber R. , Skorupa W. 
Published: March 2011

ABSTRACTResults of a computer simulation of Ostwald ripening during ion beam synthesis of a SIMOX layer are presented. Based on investigations of the as-implanted state the simulation starts with equal-sized SiO2 precipitates, homogeneously distributed in a layer. The simulation shows clearly that Ostwald ripening forms structures in such a system by means of self-organisation.This structure forming process explains in a simple and consistent manner structures of in the concentration profile like ”humps”, ”spikes” and ”banding”, which have been observed experimentally.
Synthesis of Si1-xGex-on-Insulator by 74Ge+ Ion Implantation in a Simox Substrate
Authors: Patel C.J. , Marsh C.D. , Magnusson U. , Jeynes C. , Ostling M. , NorströM H , Booker G.R. , Butcher J.B. 
Published: March 2011

ABSTRACTA single crystalline Si1-xGex overlayer on insulator is realised by the implantation of germanium into a SIMOX (Separation by IMplantation of OXygen) substrate. Two SIMOX samples were implanted with 74Ge+ at elevated temperature (≈600°C), and subsequently annealed at different temperatures and anneal ambients. The microstructure, stoichiometry, and conductivity of the Si1-xGex over-layer were studied using transmission electron microscopy, Rutherford backscattering spectrometry/ion channelling and two-probe conductivity measurements. As a result of lattice reordering after final heat treatment, and despite high defect density observed in the XTEM microstructure, the measured conductivity of the over-layer is higher than of the starting SIMOX material. These results suggest a possibility of band-gap engineering by synthesis of Si1-xGex-on-insulator.
In-Plane Magnetic and Structural Anisotropies in NI and FE Films Produced by Ion-Assisted Deposition
Authors: Lewis W. A. , Farle M. , Clemens B. M. , White R. L. 
Published: March 2011

ABSTRACTWe report the results of our microstructural investigations into the origin of in-plane uniaxial magnetic anisotropies induced in Ni and Fe thin films by low energy ion beam assisted deposition. 1000 Å films were prepared by ion beam sputtering onto amorphous silica substrates under simultaneous bombardment by 100 eV Xe+ ions under an oblique angle of incidence. The induced anisotropy is studied as a function of ion-to-adsorbate atom arrival ratio, R, from values of 0 to 0.35. The maximum anisotropy field is 150 Oe for Ni and 80 Oe for Fe, but their hard axes are oriented orthogonal to each other. Asymmetric x-ray diffraction is employed to study both in-plane and out-of-plane lattice spacings and crystallographic orientation. In agreement with previous work, we find evidence of a anisotropic in-plane strain of magnitude 0.2-0.5%. In all films, the direction perpendicular to the ion bombardment is compressed relative to parallel. The uniaxial magnetic anisotropy is correlated with this in-plane anisotropic strain using a simple magnetoelastic model.
Surface Microstructure of High Temperature Beryllium Implanted with Deuterium
Authors: Touhouche K. , Terreault B. 
Published: March 2011

ABSTRACTWe have investigated implantation temperature effects on the formation of blisters on the surface of Be foils implanted with low energy, 1.5 keV, deuterium ions to doses ranging from 3×1016 to 1.2×1018 ions cm-2, a dose exceeding by far the saturation (≈1.8×1017 ions cm-2: 30% at.). The implantation temperature was varied from 293 K (RT) to 983 K. The samples have been characterized by scanning electron microscopy (SEM). For saturated samples, blisters were present even at high temperatures, viz 983 K, and no blisters were found for samples implanted below 20% at.. However, on samples in which a dramatic grain growth has been observed, blisters were found to decorate the grain boundaries and to interconnect with each other. The average blister diameter increases with increasing temperature, thus indicating the thermodynamical aspect of blister formation and coalescence. On the other hand, for low temperature (473 K), the surface structure that has developed is similar to that at RT, except for an increased most probable blister diameter and blister density, and there was no indication that the blisters ruptured. The blister skin thickness agrees well with the projected range of the implanted ions. Over-saturated samples at RT retained only ≈30% at., corroborating the observations that some blisters formed on already ruptured ones.
Oxidation of Si via Solid State Interfacial Reaction with Deposited Sn-Doped In2O3
Authors: OW Yang Cleva W. , Shigesato Yuzo , Paine David C. 
Published: March 2011

ABSTRACTWe have developed a novel solid-state method for forming interfacial silicon dioxide by a two step process of rf sputtering tin-doped indium oxide (ITO), a transparent conductor, onto Si substrates followed by annealing at 800°C in flowing ultra-high purity nitrogen. TEM, XRD, FTIR, and C-V measurements were used to characterize the microstructure and morphology of as-deposited and annealed samples. The silicon dioxide layer grows interfacially between Si and In2O3 and, for a 5 nm thick oxide, is planar on a 2–4 monolayer scale over hundreds of nm. The kinetics of the solid-state interfacial oxidation reaction were studied and a model has been developed.
Hot Electron Phenomena in Transport Across Metal-Semiconductor Structures
Authors: Ludeke R. , Bauer A. 
Published: March 2011

ABSTRACTBallistic Electron Emission Microscopy (BEEM) is shown to be a versatile spectroscopic tool to investigate scattering phenomena of energetic electrons. Two examples are given for obtaining numerical values of scattering parameters. Thus the elastic and inelastic mean free paths are deduced from model fits to attenuation data for thin Pd films deposited on Si(111) and Si(100) substrates. In the second example, the quantum yield for electron-hole pair production through impact ionization of hot carriers injected into Si(111) is directly measured over an energy range from 1-7 eV.
Formation of Chemically Clean and Morphologically Smooth PtSi/Si Interfaces
Authors: Das Suhit R. , Xu D-X. , Phillips J. , McCaffrey J. , LeBrun L. , Naem A. 
Published: March 2011

ABSTRACTPtSi/Si interfaces have been formed by depositing Pt layers on chemically cleaned, lightly doped, n-type Si (100) wafers in a UHV magnetron sputter-deposition system using ultra high purity Ar as the sputter gas, followed by ex-situ silicidation in N2ambient utilizing a 3-step rapid thermal annealing (RTA) process. The polycrystalline PtSi layer, with oriented grains ranging in size from 50-100 nm, exhibits a columnar growth morphology. The PtSi/Si interface is planar with interface roughness in the order of 5 nm peak-to-peak. Auger depth profile shows uniform composition through the PtSi layer and a clean and chemically abrupt PtSi/Si interface.
Ultra-Low Resistance Ni-Based Contacts to n-InP: the Dependence of Contact Resistivity on the Condition of the Metal-Semiconductor Interface
Authors: Fatemi Navid S. , Weizer Victor G. 
Published: March 2011

ABSTRACTNear-theoretical-minimum values of specific contact resistivity, ρc (in the mid-to-low E-8 Ω-cm2 range) have been achieved for Ni-based contacts to moderately doped (2E18 cm−3) n-type InP. In each case these values are an order of magnitude lower than those previously achieved. These ultra-low resistivities are shown to result when the metallurgical interaction rate between the contact metal and the semiconductor is sufficiently reduced. Several methods of reducing the metal-InP reaction rate and thus achieving lowered resistivity values are demonstrated. We show, for instance, that the introduction of a thin (100Å) Au layer at the metal-InP interface retards metal-semiconductor intermixing during sintering and results in a ten-fold reduction in pc. Another method consists of ensuring the perfection of the near-surface InP lattice prior to and during contact deposition process. Use of this technique has enabled us to fabricate, for the first time, Ni-only contacts with pc values in the low E-8 Ω-cm2 range. We present an explanation for these observations that is based upon the magnitude of the In-to-P atomic ratio at the metal-InP interface.
Shallow Ohmic Contacts to p-InGaAs Based on Pd/Ge with Implanted Zn or Cd
Authors: Ressel P. , Strusny H. , Fritzsche D. , Kräutle H. , Mause K. 
Published: March 2011

ABSTRACTThe development of shallow ohmic contacts for the thin p-InGaAs layer (p≤1*1019 cm−5) of InP-based heterojunction bipolar transistors is a severe challenge to contact technology. While standard metallizations reveal several drawbacks, Pd/Ge-based systems emerged as promising candidates. In this work, Zn or Cd was implanted into the inner Pd contact layer for lowering contact resistivity. We present a study of the electrical and metallurgical properties of Pd/Ge contacts to p-InGaAs, and the influence of Zn and Cd implanted into the metallization. The resistivity of implanted and annealed (450-575 °C) contacts is reduced up to one order of magnitude compared to the unimplanted contact. Backside SIMS measurements show that annealing leads to a very limited interdiffusion at the interface. Cd and Zn diffuse into the InGaAs layer to a depth of approx. 30 and 40 nm, respectively. Due to these features, this implanted Pd/Ge contact scheme is a promising candidate for shallow contacts to p-InGaAs.
Segregant-Assisted Growth of SiGe/Si Heterostructures and their Optical Properties
Authors: Shiraki Y. , Fukatsu S. , Fujita K. , Usami T. 
Published: March 2011

ABSTRACTA method to realize high quality SiGe/Si heterostructures where surface segregation seriously deteriorates the interface integrity is discussed. After clarifying the mechanism of surface segregation, a new technique, called segre-gant-assisted growth (SAG), where atoms having a strong segregation tendency are introduced at heterointerfaces is proposed and its advantages are demonstrated. Intersubband transition of electrons in the conduction band can be clearly observed even in narrow quantum wells (QWs), and the well width dependence reflecting the square shape potential is obtained in the absorption peak energy. Gas source MBE (GSMBE), which is considered to be quasi-SAG with hydrogen generated at the growth front acting as a segregant, is shown to provide high quality SiGe/Si heterostructures with abrupt interfaces. Highly efficient band edge luminescence is observed in the QWs grown by the SAG method, especially by GSMBE, and the quantum confinement effect is confirmed. Electroluminescent diodes providing band edge luminescence are fabricated by this method, suggesting a high potential for SiGe/Si heterostrucutres in device applications.
Stability of Sulfide Passivated Gallium Arsenide Surfaces
Authors: Solomon J. S. , Petry L. , Smith S. R. 
Published: March 2011

ABSTRACTThe chemical state of (NH4)2S treated (100)GaAs surfaces exposed to ambient conditions for several days was correlated with barrier height measurements. Surface chemistry was characterized by Auger electron spectroscopy and barrier heights were calculated from C-V measurements obtained with a Hg probe. Results show that surfaces are chemically and electrically unstable for several hours following the sulfide treatment. The chemical and electrical states continually changed during ambient exposure up to 300 hours. Although strictly speaking, the surfaces were not passivated, the presence of sulfur did inhibit the formation of Ga and As oxides and the incorporation of carbon. In addition, stable, low barrier heights were observed after ambient exposure for several hours. Barrier heights from C-V measurements using deposited Au and Al contacts were compared to the barrier heights obtained with a Hg probe.
Mechanistic Study of the Deposition of Metals from HF Solutions onto Silicon Wafers
Authors: Parks H.G. , Hiskey J.B. , Yoneshige K. 
Published: March 2011

ABSTRACTProcess chemicals in use today are quite pure, depending on the grade used but can easily be contaminated with metal ions through improper handling or storage techniques. Such metal impurities, if deposited on wafer surfaces during processing can increase reverse-bias junction leakage, degrade oxide breakdown strength and increase metal oxide semiconductor capacitor leakage which in turn can adversely affect the function of ultra large scale integrated (ULSI) circuits. Because of these device effects and since metal contamination can come from several sources it is important to know the deposition level and mechanism on Si wafers from a given process solution. HF based process solution have been investigated due to their historical use in patterning, etching, and their increased use in advanced wafer cleaning processes.Multi-contaminant experiments have been designed to study the probability of, and mechanism for deposition. It is shown that in general single element deposition is predicted by electrochemical considerations based on redox reactions, however, potential complex synergistic interactions can cause deviations from the simple theory. Specifically, Sn is shown to inhibit the deposition of Ag, and Mo does not deposit in proportion to the amount of Mo in solution, but does deposit on wafers in the presence of Cu and/or Ag. Detailed analysis of Cu and Ag from BOE and Cu from HF shows the deposition: is statistically uniform over bare Si wafers, is independent of substrate doping and rinse time, does not occur on SiO2 is linear with time (up to 25 min) and solution concentration ( up to 500 ppb), shows an Arrhenius behavior with temperature (15 - 55°C) and increases surface micro-roughness. Interpretation of these results with an Evans diagram indicates the deposition is mass transport limited, allowing a first order quantitative theoretical interpretation of the deposition process.
Atomic Scale Control of Si(001) Surface by Wet-Chemical Treatment
Authors: Morita Yukinori , Tokumoto Hiroshi 
Published: March 2011

ABSTRACTSTM observation of the wet-chemical treated Si(001) surface was carried out. On the surface treated by 1%-HF solution (pH=2), the STM images were always rough and hardly exhibited the atomic feature. The STM images on the surface treated by HCl:HF=19:1 solution (pH<1) after 1%-HF dipping were also rough in a macroscopic scale but they occasionally shown atomlike corrugation in a magnified scale. The atomlike corrugation tends to align toward [110] directions which may reflect the ordered structure on Si(001) surface. This result indicates that in the case of etching by the HCl:HF=19:1 solution, the microscopic roughness on Si(001) surface tends to decrease, which might be explained by the steric hindrance effect during extremely slow etching.
Structural and Electrical Characterization of Hydrophobic Direct-Bonded Silicon Interfaces
Authors: Tam Gordon , d'Aragona F. Secco , Theodore N. David 
Published: March 2011

ABSTRACTDirect wafer bonding is a viable technique for fabricating high-voltage devices. An understanding of the microstructure and electrical behavior of the bonded interface is critical for device fabrication. In this paper, we investigated the microstructure of the silicon-to-silicon bonded interface using cross-sectional transmission electron microscopy and the corresponding electrical behavior using spreading resistance probing. Results indicate that oxide precipitates were present at the bonded interface when Czochralski silicon wafer were used in the process. Oxide precipitates were noticeably absent from the bonded interface when float zone wafers were bonded to each other. We find that oxide precipitates at the interface arise not due to the residual oxide at the surface prior to wafer bonding but due to gettering of oxygen from the Czochralski wafer. Spreading resistance measurements show occurrence of a high resistivity region at the bonding interface whether or not oxide precipitates are present.