bluuebunny/crossref_metadata_2025_split huggingface dataset:
Electrical Properties of Ion Implanted Poly (P-Phenylene Sulfide)
Authors: Abel J.S. , Mazurek H. , Day D.R. , Maby E.W. , Senturia S.D. , Dresselhaus G. , Dresselhaus M.S. 
Published: March 2011

ABSTRACTIon-implantation can increase the electrical conductivity of the polymer poly (p-phenylene sulfide) (PPS) by ~ 14 orders of magnitude. This conductivity increase, which is stable under ambient conditions, is studied as a function of temperature, ion energy, fluence and species, using a novel technique, based on microelectronics processing, capable of accurately measuring conductivities as low as 10−10 (Ω-cm)−1. Mechanisms for the enhanced conductivity of PPS are discussed in relation to our measurements.
Crystalline to Amorphous Transformation of Fe3B By 1 MeV Electron Irradiation
Authors: Mogro-Campero A. , Hall E.L. , Walter J.L. , Ratkowski A.J. 
Published: March 2011

ABSTRACTSpecimens of amorphous Fe75B25 produced by rapid quenching from the melt were annealed to complete crystallization and subjected to 1 MeV electron irradiation in a transmission electron microscope at room temperature and at 130 K. The irradiation was interrupted at various intervals in order to obtain bright field images and diffraction patterns. The Fe3B crystals did not become amorphous at room temperature, even after damage levels of several dpa, whereas at 130 K the crystalline to amorphous transformation was observed to be complete at damage levels below 1 dpa. The results are combined with those of ion irradiation work on Fe3B; qualitative agreement is found between Fe3B and previous work on the Zr3Al alloy concerning their response to displacement damage by electron and ion irradiation.
Radiation Induced Amorphous Transformation in Intermetallic Compounds
Authors: Brimhall J. L. , Kissinger H. E. , Charlot L. A. 
Published: March 2011

ABSTRACTIntermetallic compounds and ordered phases in the Ti-Ni, Ti-Fe, Re-Ta, and Mo-Ni systems became amorphous after high energy, ion irradiation. Compounds in the Ni-Al and Fe-Al systems remained crystalline and formed dislocation networks after similar irradiation. The ease of amorphous formation correlated best with the lack of solubility within the phase field. The high internal energy of the defect state in these limited solubility alloys is believed responsible for the tendency to transform to an amorphous state. A correlation with other properties such as atom size ratio or outer electron concentration was not found.
Structural Analysis of A–15 Nb3Al Substrates Implanted With Heavy Doses of Boron ions
Authors: Treuil Clapp Mireille 
Published: March 2011

ABSTRACTVery heavy doses of B ions, up to 22 At%, were implanted into Nb3Al substrates depleted of Al. Energies as high as 1 MeV were used. The surface composition was Nb3Al1−xBx where x varied from 0 to 1 over a distance of 20,000Å. Auger analysis was done to determine composition depth profiles. Structure was analyzed with a diffractometer using Cr radiation. The x-rays sampled primarily the implanted layer. Phase analysis was carried out as a function of incremental heat treatments up to 1000 C. The A–15 phase was always present although its composition was uncertain. The tetragonal Nb3B2 phase appeared after annealing at 95OC. Superconducting transition temperatures were measured at all stages; no increase in Tc above that of the substrate was observed.
Principles of Ion Mixing
Authors: Matteson S. , Nicolet M.-A. 
Published: March 2011

ABSTRACTSeveral mechanisms can cause atomic relocation as a result of ion irradiation. Experiments are reviewed that provide information on the atomic redistribution within a solid. Predictions of different models, when compared with these results, shed light on the dominant processes. Sucesses and problem areas are discussed and possible practical applications of the results are explored.
Intermixing of Chromium and Copper by Argon Ion Recoil Implantation
Authors: Baron N. , Greggi J. , Schreurs J 
Published: March 2011

ABSTRACTArgon ions at 150 keV and fluences ranging from 5 × 1015 to 4.8 × 1017 ions/cm2 were used to bombard 60 nm chromium layers deposited on copper. The resulting concentration profiles were determined by AES and thin film microstructural analyses were performed using an STEM equipped with an energy dispersive X-ray spectrometer (EDS). The concentration profiles are in qualitative agreement with the theory of radiation induced mixing. At fluences up to 2.4 × 1017 Ar+/cm2, metastable solid solutions of increasing copper content in BCC chromium are formed. At the highest fluence (4.8 × 1017 Ar+/cm2 ), chromium rich precipitates form in the copper matrix.
The Surface Behavior of a Binary Alloy During Production by Ion Implantation
Authors: Reynolds G. W. , Vozzo F. R. , Alias R. G. , Knudson A. R. , Lambert J. M. , Treado P. A. 
Published: March 2011

ABSTRACTThin surface copper-nickel alloys were prepared by ion implantation at 90 keV. During the implantation of one pure element by the other the sputtered products were collected on catcher foils at different stages from the beginning of the implant through to the steady state configuration of the target surface. The collector foils and targets were analyzed to determine the behavior of the sputtering yields during implantation and for the change in surface composition at the selected fluence. The total sputtering yield for the target and the effective elemental sputtering yields for each component appear to be functions of the changing surface fractions, the self ion sputtering yield of the implanted species, and the elemental sputtering yield of the initial target species. A model relating these parameters is presented.
Electronic Structure of Divalent Defects in Tetrahedrally Bonded Amorphous Materials
Authors: Lin S. Y. , Lucovsky G. , Guha S. , Payson J. S. 
Published: March 2011

ABSTRACTThis paper describes a calculation of twofold-coordinated (or divalent) intrinsic bonding defects in a-SiSn:H alloy films. The motivation for this study comes from experimental studies of the electronic and optical properties of a- Si, Sn:H alloys which indicate dramatic changes in the electronic and photoelectronic properties for small concentrations of Sn (approximately 1–2 at. %). We have used a cluster Bethe lattice structural model and an empirical tight-binding Hamiltonian to investigate the electronic properties of tetrahedrally bonded Sn atoms and neutral Sn defect centers (T2o and T3o) and in an a-Si host. We find that: (C) fourfoldcoordinated Sn atoms simply promote a reduction in the optical bandgap, with the energy gap disappearing for Sn concentrations of about 20 to 30 at. %; (2) neutral dangling bonds (T2o) or threefold-coordinated Sn atoms generate a localized state in the gap that is iower in energy than the corresponding neutral Si atom dangling bond; and (3) divalent (T2o) or twofold-coordinated Sn atoms give rise to two states in the gap, an occupied state that is lower in energy that either the Sn or Si dangling bond, and an empty state that is just below the conduction band edge. We show that the electronic and optical properties of the a-SiSn:H alloys can be understood in terms of a model in which there are relatively high densities of unhydrogenated Sn divalent sites and/or Sn dangling bonds.
Study of Trapping and Recombination In a-Si:H By Means of Infrared Enhancement Spectra of Photoconductivity
Authors: Wenhao Wu , Changhua Qiu , Shifu Zhao , Daxing Han 
Published: March 2011

ABSTRACTIR re-excitation of non-equilibrium carriers in undoped a-Si:H has been used to probe the profile of the distribution of deep traps. In a dualbeam experiment, after turning off a pump light, the trapped carriers are re-excited by an IR probe light which causes the photoconductivity(PC) to pass through a maximum, σmax, before settling down towards its steady state value, σs. σmax depends on the time interval td between turning off the pump light and turning on the probe light in a manner Δσ=σmax-σs∞td-α(T) Based on the multiple trapping (MT) model, the distribution of deep traps has been deduced from the temperature dependences of α(T).
The Photoconductivity Exponent For Recombination At Dangling Bonds In a-Si:H
Authors: Vaillant F. , Jousse D. 
Published: March 2011

ABSTRACTA theoretical model has been developed for recombination at dangling bonds which explains the γ variations between 0.5 and 1 depending on the Fermi level position. The occupation probabilities of the T3+, T3° and T3- states under illumination have been calculated using the statistics of correlated levels. The γ exponent is derived through a parametric representation of the equations of detailed balance and charge conservation. A good agreement with experiment is obtained with a dangling bond density of 5×1015 cm-3, a placing of the T3° level at 0.95 eV below Ec, an effective correlation energy of 0.4 eV and a charged to neutral capture cross section ratio of 50.
Novel Properties of a-SI:H Prepared by Dual Ion Beam Sputtering
Authors: Windischmann H. , Collins R. W. , Cavese J. M. 
Published: March 2011

ABSTRACTFilms of a-Si:H were deposited by dual ion beam sputtering using a new configuration in which both the argon and hydrogen beam sources are directed at the silicon target. This geometry also permits independent control of the hydrogen and argon energy and particle flux. Infrared absorption mealurents show that even for high hydrogen concentrations, the 2000 cm-1 Si-H stretching band is dominant. This result is in contrast with the more conventional configuration in which the H soyrce is directed at the substrate, resulting in films with dominant 2100 cm-1 mode. This suggests that the precursors resulting in H-incorporation are different for the two configurations. In fact, IR reflectance and SIMS analysis of the silicon sputtering target reveal hydrogen is incorporated, peaking at about 30 Å below the target surface. A strong increase in the photo and dark dc conductivity occurs as the hydrogen ion enery is reduced below 30 eV, suggesting the importance of preventing high energy back-scattered H ion bombardment of thS film. At a H ion energy of 8eV, the values are 2x10-5 (AM1) and 2x10-9 (ohm-cm-1), respectively. Spectroscopic ellipsometry measurements of films reveal a Si-Si bond packing greater than that of low Hcontent a-Si prepared by LPCVD even up to H contents as high as 24%. Above 25% a microstructural transition is observed, verified by SEM, resulting in an increase in the density of voids, (which appears to be responsible for a sudden drop in the hydrogen-induced compressive stress) and accompanied by a shift in the dominant stretching mode energy.
Dopant Incorporation and Doping Efficiency in a-Si:H and a-Ge:H
Authors: Stutzmann Martin 
Published: March 2011

ABSTRACTDoping of hydrogenated amorphous silicon and germanium with boron, phosphorus, and arsenic is investigated. The incorporation of the dopants from the gas phase into the solid film is found to differ strongly for the various dopant-host systems. The doping efficiency is calculated from measurements of the density of dangling bond defects and of shallow band-tail states as a function of the doping level. A common square root dependence of the efficiency on dopant gas concentration is obtained.
Measurements of Light-Induced Degradation in A-Si, Ge:H, F Alloys,
Authors: Kolodzey J. , Aljishi S. , Smith Z E. , Chu V. , Schwarz R. , Wagner S. 
Published: March 2011

ABSTRACTThe effects of illumination on the optical and electronic properties of narrow gap hydrogenated and fluorinated amorphous Si-Ge (a-Si1-xGex:H, F) alloys have been evaluated. A series of alloys with optical gaps ranging from 1.30 eV to 1.64 eV has been light soaked at ∼1 sun intensity for 354 hours. Measurements of sub-gap absorption, photo- and dark conductivities and dark conductivity activation energy were made on alloys in the annealed and the light-soaked states. The results indicate that samples with optical gaps ≳ 1.4 eV degrade significantly. The 1.3 eV sample shows no degradation in its optical or electronic properties except for a factor of 5 increase in the dark conductivity.
Control of a-Si:H Film Properties by Phoyo-Assisted Plasma CVD
Authors: Fkuda Nobuhiro , Miyachi Kenji , Tanaka Hirofumi , Igarashi Takashi , Yamamyto Sadaaki 
Published: March 2011

ABSTRACTCO2 laser irradiation onto growing a-Si:H surface caused a decrease of the optical bandgap down to 1.63 eV and a significant increase of the photosensivity. Primary effect of the laser irradiation was a conventional substrate heating, while the optical bandgap narrowing could not be explained by heating effect alone.
Status of Amorphous Silicon and Related Alloys Prepared by Photochemical Vapor Deposition
Authors: Konagai Makoto 
Published: March 2011

ABSTRACTA review is given of the current status of amorphous Si(a-Si) and related alloys prepared by photo-CVD. Preparation techniques and film quality of the following materials will be reviewed;
•undoped a-Si films,•highly conductive n-type and p-type μc-Si films, a-SiGe films.•a-SiC films, superlattice structures.Finally, the present status of a-Si solar cell performance prepared by photo-CVD will be introduced and the merit of photo-CVD will be discussed.
Electronic Transport and the Density of States Distribution in a-(Si, Ge):H, F Alloys
Authors: Aljishi S. , Smith Z E. , Slobodin D. , Kolodzey J. , Chu V. , Schwarz R. , Wagner S. 
Published: March 2011

ABSTRACTThe electronic and optical properties of amorphous silicon-germanium alloys produced by d.c. and r.f. glow discharge are reported. Data on the sub-gap absorption, dark and photo conductivities, drift mobilities and drift mobility-lifetime products are used to propose a density of states model.
a-(Si, Ge):H, F Alloys Prepared from SiH4 and GeF4
Authors: Slobodin D. , Aljishi S. , Okada Y. , Shen D.-S. , Chu V. , Wagner S. 
Published: March 2011

ABSTRACTThe properties of a-(Si, Ge):H, F alloys prepared by glow discharge deposition from SiH4 and GeF4 are described. The measured IR absorption spectra, sub-gap absorption spectra, dark conduction activation energies, carrier drift mobilities and deep trapping lifetimes of these alloys are similar to those of alloys prepared from SiF4, GeF4, and H2. However, they have over an order of magnitude lower photoconductivity over most of the composition range. Infrared absorption measurements indicate that these alloys have a fluorine content less than 1.5 at.% and a Si-H2 content that increases with germanium concentration.
NMR and ESR Studies on a-Si1-x Gex:H Films Prepared by Glow Discharge and Magnetron Sputtering
Authors: Shimizu T. , Kumeda M. , Morimoto A. , Tsujimura Y. , Kobayashi I. 
Published: March 2011

ABSTRACTProperties of a-Si1-xGex:H films prepared by magnetron sputtering (MG) and glow discharge decomposition (GD) were compared by means of NMR, ESR, IR and hydrogen-evolution measurements. For MG films, the content of dispersed H is roughly independent of x while the content of clustered H decreases with x. For GD films, both the contents of dispersed and clustered H decrease with x. ESR results reveal that most defects in the films are Ge dangling bonds and that the number of dangling bonds per Ge atom is roughly independent of x for MG films whereas it increases largely with x for GD films. Therefore the content of dispersed H has a good correlation with the number of Ge dangling bonds per Ge atom in a-Si1-xGex:H films. The ratio of the intensity of the IR peak at 2100 cm-1 to that at 2000 cm-1 decreases and increases with x, respectively, for MG and GD films, and the ratio of the intensity of the low temperature H evolution peak to that of the high temperature H evolution peak decreases and increases with x, respectively for MG and GD films.
Effective p+-Doping of a-Si:H and a-Sic:H Layers by Plasma Assisted Boron Diffusion
Authors: Mohring H.-D. , Bauer G. H. , Bilger G. , Nebel C. E. 
Published: March 2011

ABSTRACTDoping of a-Si:H and a-SiC:H has been performed by plasma enhanced boron migration from thin (5–30 nm) Si0.2B0.8 layers on top of the substrate into the growing i-film. Transport coefficients for this plasma assisted diffusion (PAD) evaluated from SIMS profiles (D* = 10−15 … 10 cm2/s for a-Si:H, 10−15 cm2/s for a:SiC:H) by far exceed those for thermal diffusion after film deposition (10−21 cm2/s). Boron profiles are strongly governed by deposition parameters like substrate temperature, types and energies of radicals growing the film. Boron migration can be modelled assuming particle extraction from the network to the surface by bombardment of ions and atoms and high surface mobility of BHx radicals as a result from interaction with the plasma. Temperature dependent dark conductivity measurements show doping efficiencies comparable to B2H6 gas phase doping, but leaving plasma parameters optimized for i-film Leposition unchanged. Thin a-SiC:H layers are effectively p+-doped without affecting transmission, as no layer is optically detectable after PAD.
Properties of the Interface Between Amorphous Silicon and Nitride
Authors: Tsai C. C. , Street R. A. , Ponce F. A. , Anderson G. B. 
Published: March 2011

ABSTRACTThe structural, compositional and electronic properties of the a-Si:H/a-SiNx:H interface are reported. High resolution TEM and light/dark ESR studies conclude that the interface has a finite width of the order of 10 Å. In addition, there is a high density of charges residing near the interface. Band bendings occur in both a-Si:H and a-SiNx:H, resulting in few neutral dangling bonds in the a-Si:H/a-SiNx:H multilayer structure. The depletion width in the nitride is of the order of 100 Å. The slow decay of the LESR in multilayers with thin sublayers is attributed to charges trapped in the slow states in the nitride.
The Origin of Slow States at the Interface of a-Si:H and Silicon Nitride
Authors: Street R. A. , Tsai C. C. 
Published: March 2011

ABSTRACTTransient photoconductivity is used to investigate the origin of slow states near the interface of a-Si:H and silicon nitride. A graded composition of the nitride layer near the interface greatly increases the density of slow states. We deduce that slow states are bulk nitride traps and that the magnitude of charge storage is largely determined by the composition dependence of the localization radius of electrons within these traps. The kinetics of charge storage and release are found to be very different and are interpreted in terms of an activation step at the interface.
Properties of a-Si:H and a-SiGe:H Films Deposited by Photo-Assisted CVD
Authors: Rocheleau R. E. , Jackson. S. C. , Hegedus S. S. , Baron B. N. 
Published: March 2011

ABSTRACTChemical vapor deposition techniques, in particular plasma enhanced CVD, have been used to produce high quality a-Si:H materials. Continuing research is directed toward increased device performance, improved stability, and translation of scale to commercial production. A part of this effort is the evaluation of alternate CVD techniques which in addition to providing technical options for high efficiency and long term stability are likely to lead to improved understanding of the relationships between deposition processes and material properties. A relatively new technique for depositing a-Si:H is photo-CVD which utilizes ultraviolet light to initiate the decomposition of silane or disilane. The best results from both materials properties and device efficiency points of view have been achieved using mercury sensitized photo-CVD. Recently, a 10.5% efficient a-Si:H p-i-n photovoltaic cell, fabricated by photo-CVD, was reported [1]. A limitation in photo-CVD has been preventing deposition on the UV transparent window. In this paper we describe a new photo-CVD reactor with a moveable UV-transparent Teflon film and secondary gas flows to eliminate window fouling. The deposition and opto-electronic characterization of intrinsic a-Si:H and a-SiGe:H and p-type a-SiC:H are described. Finally, preliminary results of p-i-n solar cells are presented.
UHV Interface Studies of Palladium Silicide Formation on Hydrogenated Amorphous Silicon Films
Authors: Rhodes H. E. , Apai G. , Rivaud L. , Hung L. S. , Mayer J. W. 
Published: March 2011

ABSTRACTSilicide formation by reaction of palladium metal (Pd0) with hydrogenated amorphous silicon (a-Si:H) substrates was studied with Rutherford backscattering spectrometry (RBS), forward recoil spectrometry, x-ray photoelectron spectroscopy (XPS), and transmission electron microscopy (TEM). Upon low-temperature (200° C) annealing, RBS and TEM show a single-phase Pd2Si. This phase grows with the square root of time, and the activation energy is identical to that of the corresponding metal on single-crystal silicon substrates. The growth is slightly faster for hydrogenated amorphous silicon, which is attributed to its amorphous structure. During silicide formation, the hydrogen is released from silicides and presumably outdiffuses into a vacuum without interfacial accumulation. Thus, barrier formation does not occur, and the presence of hydrogen in the substrates has no effect on silicide growth.The silicide electronic structure (core level binding energies, lineshapes, and d-band filling) of Pd2 Si on a-Si:H is identical to that of Pd2 Si formed on cr stalline silicon. Binding energy and peak shape analysis show the Pd2Si/Pd0 interface to be composed of one additional phase, Pd4Si, which has a well-defined binding energy (335.8 eV) and a narrow (FWHM = 1.1 eV), symmetric line shape. It has long been postulated that interface phases may be important in determining the phase sequence in silicide growth and the dominant diffusing species. This Pd4 Si interface phase may be important in understanding palladium silicide growth.
Transport Properties of Amorphous Silicon / Silicon Oxide Heterostructures
Authors: Steemers H. , Mort J. , Chen I. , Jansen F. , Grammatica S. , Kuhman D. 
Published: March 2011

ABSTRACTThe transport of excess carriers in glow-discharge deposited a-Si:H/insulator heterostructures has been studied by time-of-flight and xerographic discharge techniques. Efficient injection of photocarriers from a-Si:H into, and transport through, relatively thick SiOx:N:H has been achieved. A mobility-lifetime product approaching 18−6 cm2V−1 is found for electrons in SiOx:N:H, and time resolved measurements indicate a room temperature mobility of 5×10−6 cm2v−1s−1 at a field of 2×104 Vcm−1, suggesting an electron lifetime of the order of 8.2 seconds. The results are contrasted with transport measurements on thermally grown SiO2 on Si and a transport model involving hopping through defect states within the gap of SiOx:N:H is discussed.
Optoelectronic Properities of A-Ge:H/A-Si:H Superlattic Structures
Authors: Wronski C. R. , Persans P. D. , Abeles B. , Tiedje T. , Hicks M. 
Published: March 2011

ABSTRACTThe optoelectronic properties of multilayer a-Ge:H/a-Si:H superlattices with bandgaps between ˜1.4 and 1.1eV are presented. The dependence of the electronic properties on the band alignment and the layer thicknesses is established and quantified. Particular emphasis is given to properties relevant to practical device applications and which involve carrier transport perpendicular to the layers.
Impurities and Metastable Centers in Amorphous Silicon Solar Cells
Authors: Carlson D. E. 
Published: March 2011

ABSTRACTAmorphous silicon solar cells are adversely affected by impurities through the creation of traps, recombination centers and metastable centers. The microstructure of discharged-produced, hydrogenated amorphous silicon (a-Si:H) appears to be strongly affected by the presence of impurities in the discharge atmosphere. A model is developed in which impurities create microvoids in a-Si:H, and traps, recombination centers and metastable centers are associated with the internal surfaces of the microvoids. In this model, hydrogen plays an important role in determining the electronic activity and diffusivity of impurities, and metastable centers are created by the trapping of holes near microvoids and the induced motion of hydrogen on the internal surfaces of the microvoids.