bluuebunny/crossref_metadata_2025_split huggingface dataset:
Surface Modification and Radiation-Induced Segregation
Authors: Rehn L. E. 
Published: March 2011

ABSTRACTLarge changes in the distributions of alloying components have been observed in a wide variety of alloys during ion bombardment. This metastable, radiation-induced segregation (RIS) results from the preferential transport of alloying components by defect fluxes. Since the number of radiationinduced defects can exceed the number of implanted ions by several orders of magnitude, RIS can be highly efficient in modifying near-surface alloy compositions. In this paper, the general features of RIS are described. Aspects which are pertinent to the modification of materials by ion beams are emphasized. Examples are given of surface modifications which utilize RIS effects.
Electrical Properties of the Ion-Implanted Pd1−x Bx System
Authors: Mendoza-Zelis L. , Traverse A. , Chaumont J. , Bernas H. , Dumoulin L. 
Published: March 2011

ABSTRACTThe resistivity (and resistivity temperature dependence) of low temperature B implanted Pd films was measured at B concentrations up to x ֮0.55. Both properties indicate that the evolution of the system towards an amorphous structure sets in at about x ֮0.30 (the deep eutectic composition). The previous discovery of superconductivity by Stritzker and Becker at high values of x is confirmed. Annealing properties of the system were also investigated.
Study of Metastable Fe-W Films
Authors: Göltz Gerhard , Fernandez Rouel , Nicolet Marc-A. , Sadana Devendra K. 
Published: March 2011

ABSTRACTXenon irradiation of Fe-W multilayers at room temperature (R.T.) can produce two types of metastable states: low doses (< 1 × 1016 Xe/cm2 ) extend the equilibrium solid solubility of W in Fe and vice versa, maintaining the equilibrium b.c.c. lattice structure of Fe and W; at high doses (> 1 × 1016 Xe/ cm2 ) and in the vicinity of the composition Fe70W30, amorphization can occur. In comparison, RF sputter-deposited FexWl-x films were amorphous over the whole range (0.35<x < 0.79) investigated. The recrystallization temperatures of these amorphous layers exceed 600°C for 15 min vacuum annealing. Whereas Fe-W compounds always form during thermal annealing, these compounds are normally not found after Xe-irradiation of multilayers.
Structural and Mechanical Properties of Ion Implanted Al and Cu
Authors: Moine P. , Delafond J. 
Published: March 2011

ABSTRACTTensile deformation experiments on Al single crystals and parallel microstructural studies by T.E.M. on specimens directly thinned prior to a Zn+ ion implantation have been carried out. An uniform concentration of 7 at % Zn has been obtained on 1200Å thick layers by implantation using multiple energies. The temperature ranges of metastable phase of these samples are different from bulk Al-Zn alloys of identical concentration. Room and 80°C temperature thermal treatments leading to an important precipitation hardening in bulk alloys do not produce any significant mechanical modification in implanted Al single crystals. T.E.M. observations do not show any supplementary scattering around Bragg spots. On the contrary, we observe the direct appearance of precipitates at 135°C and 150°C after some days annealing.High cycle reversed load fatigue test in vacuum show significant modifications of surfacedamage of an oxygen implanted copper specimen.
Superconducting Critical Temperatures of C-Implanted Al5 Structure V-Si
Authors: Gavaler J. R. , Braginski A. I. , Manocha A. S. , Appleton B. R. , White C. W. , Williams J. M. 
Published: March 2011

ABSTRACTA series of A15 structure V-Si films were sputtered with compositions ranging from approximately V90Si10 to V75Si25 . The as-deposited critical temperature onsets were between ~ 8 and 17K. Carbon levels of up to 5 at.%(average) were implanted and the films subsequently annealed at various temperatures between 650 and 1050°C. No Tc's above 17K were obtained in the C-implanted films. However enhancements of as much as ~ 9K, from ~ 8 to 17K, in highly Si-deficient films indicated that carbon was incorporated into the A15 structure of these films to form pseudo-binary V-Si-C alloys. Experimental details are given and some reasons why Tc values greater than 17K were not obtained are discussed.
Pulsed Ion Beam Annealing Of Nickel Thin Films on Silicon
Authors: Chen L.J. , Hung L.S. , Mayer J.W. , Baglin J.E.E. 
Published: March 2011

ABSTRACTHigh power pulsed ion beams have been applied to anneal nickel thin films on silicon. RBS and TEM have been performed to study ion beam induced effects. With Ba+ion beams at energy densities greater than 0.7 J/cm2and H+beams above about 1.3 J/cm2, cellular structures were found. At about 0.6 J/cm2for Ba+(about 1.0 J/cm2for H+), epitaxial NiSi2was formed. At lower energy densities, polycrystalline layers containing a mixture of silicide phases were observed. With ion beam annealing, melting starts at the Ni/Si interface and epitaxy was found at energy densities well below that required to melt Ni or crystalline Si.
Optical Imaging and Information Storage in Ion Implanted Ferroelectric Ceramics
Authors: Peercy P. S. , Land C. E. 
Published: March 2011

ABSTRACTPhotographic images can be stored in ferroelectric-phase lead lanthanum zirconate titanate (PLZT) ceramics using a novel photoferroelectric effect. These images are nonvolatile but erasable and can be switched from positive to negative by application of an electric field. We have found that the photosensitivity of ferroelectric PLZT is dramatically improved by ion implantation into the surface exposed to image light. For example, the intrinsic photosensitivity to near-UV light is increased by as much as four orders of magnitude by coimplantation with Ar and Ne. The increased photosensitivity results from implantation-induced decreases in dark conductivity and dielectric constant in the implanted layer. Furthermore, the increased photoferroelectric sensitivity has recently been extended from the near-UV to the visible spectrum by implants of Al and Cr. Ion-implanted PLZT is the most sensitive, nonvolatile, selectively-erasable image storage medium currently known.
Rapid Annealing of Implant Damage Using Thermal Radiation
Authors: Fulks R. T. , Russo C. J. , Downey D. F. , Hanley P. R. , Stacy W. T. 
Published: March 2011

ABSTRACTThe rapid annealing of implant damage using thermal radiation has been shown to be a production-worthy method of achieving good activation and minimal dopant redistribution of implanted species. The method involves the shuttered exposure of a standard 3" or 4" silicon wafer to a uniform thermal radiation front produced by a graphite heater for short times (10–30 sec). The propagation of residual damage observed by TEM is significantly less than that produced by furnace annealing and device structures annealed have electrical characteristics comparable to standard furnace anneals.
The Microstructure of Silicon-on-Insulator Structures Formed by High Dose Oxygen Ion Implantation
Authors: Pinizzotto R.F. , Vaandrager B.L. , Lam H.W. 
Published: March 2011

ABSTRACTCross-sectional and plan view transmission electron microscopy and high resolution scanning electron microscopy have been used to characterize the microstructure of silicon-on-insulator formed by high dose oxygen ion implantation. The complete microstructure was observed to be composed of a series of distinct zones. The top silicon layer was {100} single crystal with a very low dislocation density. The second layer was a mixture of fine grained polysilicon and amorphous SiO2. The third layer was pure SiO2 , followed by a second mixed layer. Finally, there was a layer of {100} silicon with an extremely high dislocation density. Some of the dislocations extended as far as 1 μm into the Si substrate. The relative widths of the layers were found to depend on the total ion fluence. The oxide layer did not occur for low doses and the two mixed layers merged into one zone. At high doses, the silicon-silicon dioxide interfaces are abrupt due to internal oxidation.
Saturation, Exchange and Retention of Implanted D/H Ions in Fused Silica
Authors: Doyle B. L. , Arnold G. W. 
Published: March 2011

ABSTRACTElastic recoil detection techniques have been used to measure hydrogen isotope profiles in fused silica implanted with 20 keV H and/or D ions. Saturation is obtained for both H and D implantations at a concentration of 2.2 × 1021 ions/cm3. H and D exchange are observed for saturated samples subsequently implanted with a different H isotope. A previously developed local mixing model of H-trapping has been extended to include retrapping and beam-induced detrapping for application to these studies. This theoretical analysis provides a good fit to the H/D saturation and isotope exchange behavior. Isochronal annealing shows that both H and D are released in a single stage centered about 550°C.
Ion Beam Deposition of Amorphous Carbon Films With Diamond Like Properties
Authors: Angus John C. , Mirtich Michael J. , Wintucky Edwin G. 
Published: March 2011

ABSTRACTCarbon films were deposited on silicon, quartz, and potassium bromide substrates from an ion beam. Growth rates were approximately 0.3 μm/hour. The films were featureless and amorphous and contained only carbon and hydrogen in significant amounts. The density and carbon/hydrogen ratio indicate the film is a hydrogen deficient polymer. One possible structure, consistent with the data, is a random network of methylene linkages and tetrahedrally coordinated carbon atoms.
A Comparison of Atomic Mixing Behaviour of Cu- Au and Cu- W Systems for Room Temperature and Low Temperature Irradiation
Authors: Wang Z.L. , Westendorp J.F.M. , Doorn S. , Saris F.W. 
Published: March 2011

ABSTRACT300 keV Kr ion irradiations with doses varying from 2× 1015 to 2× 1016 at/cm2 have been applied to initiate mixing of Cu-Au and Cu-W systems. As under normal thermodynamic conditions the Cu-Au system is miscible whereas the Cu-W system is not, the comparison of both systems provides a test for the current theories on ion-beam mixing. A pronounced difference in mixing phenomena is observed for both systems; in the Cu-Au system atomic displacements are one order of magnitude larger than those in the Cu-W system. In addition, a drastic temperature dependence of ion-beam mixing in the Cu-Au system has been found. The mixing is suppressed by lowering the substrate temperature during irradiation. These results show that radiation enhanced diffusion is the mechanism underlying the ion-beam mixing of Cu and Au. Results for the Cu-W system are consistent with a collisional mixing model.
Temperature Dependence of Ion Beam Mixing in Al
Authors: Picraux S.T. , Follstaedt D. M. , Delafond J. 
Published: March 2011

ABSTRACTThe atomic mixing of evaporated Al/Sb films and of Al/Ag films on Al<110> crystal substrates by 400 keV Xe ion beams has been investigated. Concentration depth profiles were measured in situ by 1.5 MeV He scattering as a function of Xe fluence from 2 to 32×1015 Xe/cm2. The initial mixing rates are similar at 85 and 300 K; mixing proceeds by rapid motion of Al (≈15 Al/Xe) into and uniformly through the thickness of the Sb film and by a slow motion of Sb (≈0.5 Sb/Xe) into the Al<110> substrate. More rapid Sb mixing into Al occurs for polycrystalline Al. The rate for Al into Sb slows at concentrations approaching the stable AlSb phase. Appreciably higher rates of Sb mixing into Al (2.2 to 2.8 Sb/Xe) occur at 575 K. Mixing rates for the highly soluble system, Al/Ag, are compared to the nearly insoluble Al/Sb at 85 and 300 K. Appreciably higher rates are found for Ag than for Sb, suggesting the influence of chemical driving forces even at these low temperatures.
Inadequacy of the Conventional View of Hydrogenated Amorphous Silicon
Authors: Adler D. , Silver M. , Shaw M. P. , Cannella V. 
Published: March 2011

ABSTRACTThe conventional view of the electronic structure of hydrogenated amorphous silicon is: (1) the material is characterized by a mobility gap of about 1.8 eV, with exponential band tails due to disorder and deep defect states arising from silicon dangling bonds (T3 centers); (2) substitutional doping occurs because of the formation of chargedimpurity/dangling-bond pairs, e.g. P4+ – T3-, at the substrate temperature; (3) the effective correlation of the T3 center is about 0.4 eV; (4) T3o centers are the predominant recombination center; (5) the three intrinsic ESR signals are due to electrons on T3o centers, electrons in the conduction band tail, and holes in the valence band tail. It is the purpose of this paper to demonstrate that this model is in sharp disagreement with an array of basic experimental data, and much of the evidence presented in its favor is based on self-inconsistent logic. We conclude that it is very likely that large concentrations of charged intrinsic defect pairs are present in all hydrogenated amorphous silicon films.
Electronic Transport in Hydrogenated Amorphous Silicon
Authors: Silver M. , Adler D. , Shaw M. P. , Cannella V. , McGill J. 
Published: March 2011

ABSTRACTThe puzzles regarding the magnitude of the free electron mobility in hydrogenated amorphous silicon are examined. It is suggested that highlevel double injection produces a metastable increase in the carrier mobility by neutralizing positively and negatively charged defect states thereby eliminating long-range potential fluctuations. Since these defect states cannot be neutralized under low-level or single injection, they both contribute to the modulation of the conduction band and increase the freecarrier scattering. If the latter is the predominant scattering mechanism, the neutralization of charged defects directly leads to a mobility increase under double-injection conditions. We discuss the various implications of this model, and present recent experimental results in agreement with these ideas.
Room Temperature Light Induced Electron Spin Resonauce In Undoped Hydrogenated Amorphous Silicon (a-Si:H)
Authors: Pandya R. , Zafar S. , Schiff E. A. 
Published: March 2011

ABSTRACTThe effects of illumination upon the absorption electron spin resonance spectrum of the dangling bond defect system have been studied in undoped amorphous hydrogenated silicon (a-Si:H). A small shift of the inhomogeneous envelope of the system towards higher g-value is observed at roomtemperature. The shift is not accompanied by a significant change in the signal. Results are reported which indicate that this shift is not due to illumination induced heating of the specimen or calibration changes of the spectrometer. The results may be related to previously reported optical bias effects upon transient photocurrent and photoinduced absorption studies.
Capacitance-Voltage Characteristics of Metallic Gate/Oxide/a-Si:H Mos Structures
Authors: Schropp Ruud E. I. , Snijder Jan , Verwey Jan F. 
Published: March 2011

ABSTRACTThe density of states (DOS) has for the first time been calculated throughout the entire bandgap region of undoped amorphous silicon from quasi-static capacitance-voltage (QSCV) measurements using MOS structures. The QSCV DOS is compared with the DOS obtained by the field-effect method. It is shown, that the coexistence of states of a different nature at the same bandgap level can be revealed by the temperature dependence of low frequency MOS CV measurements.
Transport Measurements in LPCVD Amorphous Silicon Obtained from Disilane.
Authors: Manfredotti C. , Gervino G. , Montaldi L. , Nastasi U. , Murri R. , Schiavulli L. 
Published: March 2011

ABSTRACTMeasurements of high temperature conductivity on a-Si:H obtained by LPCVD from Si2H6 at temperatures between 450 and 500 °C indicate clearly a change on the activation energy from 0.9 - 1.0 eV to 0.55 - 0.6 eV around 600 °K.The results are not strongly different from those obtained in GD a- SiH4:however, the coefficent of the energy shift of the mobility edge with temperature is greater by a factor of 2, while the average extension of the tail state distribution at T= 0 °K is roughly a factor 1.5 larger. The main discrepancy concerns the pre-exponential factor, which is one or two orders of magnitude larger, giving a product (NcukT)of the order of 1021 cm-1 s-1. By assuming a conduction mobility two orders of magnitude larger than the maesured Hall mobility one obtains a value for N which is only a factor four times larger than what currently assumed for a-Si:H.
Density-of-States Distribution In Disilane LPCVD Deposited Amorphous Silicon as Determinated By SCLC
Authors: Manfredotti C. , Gervino G. , Montaldi L. , Varesio R. , Zanini A. , Nastasi U. 
Published: March 2011

ABSTRACTI-V characteristics have been measured in a-Si:H films deposited from Si2 H6 by LPCVD and have been analyzed according to a direct method. DOS distribution is thickness-dependent, similarly to what has been found on SiH deposited films, with values at Fermi level ranging from below 1016 cm-3 eV-1 up to 1018 cm-3 eV-1. Deposition temperature, at least in the interval 450 - 500°C, does not seem to affect DOS distribution. Hydrogen content is pratically constant in all the films. The only possible conclusion is that only thickness influences DOS distribution and that only for thickness larger than 0.8 μm it is possible to get densities at Fermi level below 1016 cm-3 eV-1.
Thickness Dependence of the Optical and Electrical Properties of Thin A-Si:H Films
Authors: Demichelis F. , Mezzetti E. , Mpawenayo P. , Tagliaferro A. , Tresso E. , Bourquard S. , Rava P. , Mea G. Della , Mazzoldi P. 
Published: March 2011

ABSTRACTOptical and electrical properties are investigated as a function of thickness for two sets of samples of a-Si:H films deposited respectively by RF magnetron sputtering and by RF glow discharge under the same conditions. The hydrogen concentration, the transmittance and reflectance spectra in the UV-visible-NIR and the resistivity were measured for both sets of samples. Relationships between index of refraction, absorption coefficient, imaginary part of the dielectric constant, optical band gap, resistivity and the thickness are found and interpreted. The thickness dependence of these parameters is related to the larger amount of inhomogeneities present in sputtered samples with respect to glow discharge samples.
Frequency-Dependent Noise in Hydrogenated Amorphous Silicon
Authors: Bathaei F. Z. , Anderson J. C. 
Published: March 2011

ABSTRACTFlicker noise, due to trapping and emission from states in the mobility gap, leads to a spectrum in which noise power is proportional to 1/fn. Experimentally we find 0.6 <n<1.1 for an Si:H film in an n+-i-n4 structure. Theoretical development allows the extended state electron mobility, and the density of states at the conduction band edge to be obtained. Similar measurements on Schottky diodes provide the distribution of the localized state density in the mobility gap.
The Effect of Light Soaking on the Photoconductivity Response in A-SI:H
Authors: Changhua Qiu , Wenhao Wu , Shifu Zhao , Daxing Han 
Published: March 2011

ABSTRACTThe temperature dependences of response time tr and steady state photoconductivity (PC) were used to deduce the DOS at energies above the dark Fermi level. The tr and PC of annealled state A and light soaked state B were measured from 115K to 300K. Light soaking causes degradation of PC. Compared with state A, the PC response of state B is faster at low temperatures, but is slower at high temperatures. The difference between state A and state B was interpreted by a decrease of shallow traps and an increase of deep traps.
A 29Si-NMR Investigation of Amorphous Hydrogenated Silicon Nitride
Authors: Petrich Mark A. , Livengood Rhett E. , Reimer Jeffrey A. , Hess Dennis W. 
Published: March 2011

ABSTRACTWe present the results of a spectroscopic study of amorphous hydrogenated silicon nitride. The nitride was prepared by plasma enhanced chemical vapor deposition and was studied with infrared absorption (IR) and solid-state nuclear magnetic resonance (NMR) spectroscopies. This nitride film shows a particularly interesting distribution of hydrogen: hydrogen atoms are nearly exclusively bound to nitrogen.
Photoelectronic Properties of a-Si:Sex and a-Si:Tex Thermally Evaporated Films.
Authors: Wakim F. G. 
Published: March 2011

ABSTRACTThe presence of selenium (Se) or Telurium (Te) in amorphous silicon films seems to improve the quality of these films by reducing the number of unsatisfied or dangling bonds and changing the optical gap and thermal activation energy. The thermal activation energies of a-Si:Sex and a-Si:Tex were always larger than that of a-Si films. The measured optical gap can be tailored to some value between 0.8 eV and 1.8 eV depending on the use of Se or Te and on the relative concentrations. The presence of Se or Te in a-Si films seems to have the same effect as that of hydrogen in a-Si films prepared by glow discharge of silane and used in solar cells.
The Effect of Deposition Procedure on the Conductivity of Hydrogenated Amorphous Silicon Multilayer Films.
Authors: Moddel G. , Su F.-C. , Vanier P. E. 
Published: March 2011

ABSTRACTThe conductivity of multilayer P-doped amorphous hydrogenated silicon (a-Si:H) thin films is measured for films prepared with different, deposition procedures. Multilayer films are deposited by plasma enhanced CVD following a procedure in which the plasma is extinguished and the deposition chamber is filled with air or argon after the deposition of each layer. These films are compared to films grown in continuous deposition runs. The technique provides a direct means to determine the effects of continuous versus interrupted deposition and to analyze oxide interface and bulk gap state densities. Exposing the layers to air between depositions produces deleterious effects whereas the effect of argon exposure are slight. Literature values for the density of states in oxidized a-Si:H are used to provide evidence for a defective layer in very thin P-doped a-Si:H having a defect density of over 1013 cm−2 eV−1 approximately 0.3 eV below the transport level.
Electron and Hole Transport Perpendicular to the Planes of a-Si:H/ a-Si, Ge:H Compositional Superlattices
Authors: Kolodzey J. , Aljishi S. , Schwarz R. , Shen D.-S. , Quinlan S. , Lyon S. A. , Wagner S. 
Published: March 2011

ABSTRACTDrift mobilities, drift mobility-lifetime products and minority carrier diffusion lengths perpendicular to the planes of a-Si:H, F/a-Si0.35,Ge0.65:H, F superlattices have been measured over a range of well sublayer widths. The transport data suggest a transition from scattering dominated transport in states at the top of the barriers for short superlattice periods to recombination dominated transport at the bottom of the wells for large periods. The characteristic period for this transition is ˜3 nm.
Parameters Affecting Light-Induced Excess Conductivity in Amorphous Silicon Doping-Modulated Multilayers
Authors: Su F.-C. , Levine S. , Vanier P. E. 
Published: March 2011

ABSTRACTThe phenomenon of light-induced excess conductivity (LEC) which occurs in a-Si:H npnp doping-modulated multilayers is found experimentally to be dependent on several different factors. The concentrations of the dopants in n-type and p-type layers affect the Fermi level position, the height of the barriers, and also the density of defects. These parameters are altered by different choices of inert gas diluent (Ar or He) and substrate temperature T. For a given set of deposition conditions, the LEC effect can be maximized by varying the layer thickness. With undiluted silane at T = 250 °C, the effect was relatively small, reaching a maximum in relatively thick layers (540 Å). The largest effects were obtained for films deposited from silane diluted in helium, using thinner (330 Å) layers. However, for films deposited from silane diluted in argon, thS magnitude of the effect and optimum layer thickness was intermediate (440 Å). When Ts was varied, a minimum in LEC was found near 200–250° C. The influence of Sinternal field was examined by using nini, pipi and npnp multilayers. The internal field is a necessary factor to observe a large LEC effect. A compensated film shows a small LEC effect.