bluuebunny/crossref_metadata_2025 huggingface dataset:
Some Properties of Ultra Thin Oxides Grown in Afterglow Oxygen Plasma
Authors: Chen P. C. , Lin J. Y. , Hsu Y. J. , Hwang H. L.
Published: March 2011

Microwave remote plasma oxidation were used to study the oxidation of Si and SiGe samples at a lower temperature. C–V measurements were performed to investigate the trap density, and the corresponding bonding structures of thin oxide were revealed by FTIR analysis. SIMS depth profiles were used to reveal the extent of the Ge segregation in SiGe samples. The system can grow ultra thin SiO2 with lower effective trap density. And Ge segregation can be largely suppressed by atomic oxygen oxidation at a lower temperature.
HI/H2 ECR Plasma Etching of III-V Semiconductors
Authors: Pearton S. J. , Chakrabarti U. K. , Katz A. , Ren F. , Fullowan T. R. , Abernathy C. R. , Hobson W. S.
Published: March 2011

HI/H2/Ar discharges are shown to be universal etchants for rn-V semiconductors, giving rise to highly anisotropic features with smooth surface morphologies. At loy dc self bia:s (-100V) and low pressure (1 mTorr), etch rates for all III-V materials of >2000Å min−1 are possible for high HI percentages in the discharges, whereas rates greater than 1 Åm min−1 are obtained at higher pressures and dc biases. These etch rates are approximately an order of magnitude faster than for CH4/H2/Ar mixtures under the same conditions and there is no polymer deposition on the mask or within the reactor chamber with HI/H2/Ar. Auger Electron Spectroscopy reveals residue-free, stoichiometric surfaces after dry etching in this mixture. As i result, photoluminescence intensities from dry etched samples remain high with little apparent damage introduction. Changes in the near-surface carrier concentration due to hydrogen passivation effects are also negligible with HI-based mixtures in comparison to CH4-based dry etching.
A Photoluminescence Investigation of Ion Beam and Electron Cyclotron Resonance ETCH-Induced Damage on GaAs/AlGaAs Multi Quantum Well Structures
Authors: Bensaoula A.H. , Bensaoula A. , Freundlich A.
Published: March 2011

The presence of highly energetic ionic and neutral species during dry etching generates damage in device structures which significantly reduces their performance. In this study we have utilized photoluminescence spectroscopy (PL) on GaAs/AlGaAs Multi Quantum Well (MQW) structures to assess and compare the relative damage induced by the standard ion beam etch technique and the “less damaging” newer Electron Cyclotron Resonance (ECR) etch technique. MQW structures with well widths of 2.7, 6.4, 10.8, and 81 nanometers (nm) at a distance from the sample surface of 40.5, 83, 130, and 170 nm respectively were grown by molecular beam epitaxy. In order to minimize the effect of the radically different chemistries present in reactive ion etching and in ECR reactive etching we have chosen to initially compare the damage-induced luminescence degradation resulting from Ar irradiation only. The PL intensity is shown to correlate well with the ion dose and energy. At equivalent total surface erosion under Ar irradiation the ECR process is shown to cause significantly less deterioration on QW PL yield. In the ion beam case a dose corresponding to a surface sputtering of less than 100 angstroms of the AlGaAs barrier causes total extinction of the PL from the QW lying at 1000 angstroms below the surface. By comparison under similar conditions no degradation is detected in the ECR irradiation case. Even at higher ECR doses equivalent to removal of up to 30 nm from the top AlGaAs barrier layer only minimal degradation is observed.
Lattice Parameter Changes in High Dose Ion-Implanted, Pulsed Laser Annealed GaAs:Si
Authors: Compaan A. , Yao H.D. , Adams P.M. , Knudsen J.F.
Published: March 2011

Double crystal x-ray diffraction has been used to examine the lattice parameter changes which occur in heavily Si-doped GaAs obtained by ion implantation of 28Si at 180 keV with doses up to 1 x 1016/cm2. The heavily damaged, implanted layer was pulsed laser annealed with single pulses from a 10 ns dye laser operating at 728 nm with an energy density of up to 0.9 J/cm2. Plasmon Raman scattering was used at the center of the laser-annealed spots to determine the free electron concentration which reached ∼4 × 1019/cm3. Double crystal rocking curves were obtained for <400> reflections from the pulsed laser annealed area and from the surrounding as-implanted region. The results show a dilation of the lattice of up to 0.5% in the as-implanted region and in the laser-annealed region a dilation of 0.025%. The residual lattice dilation after annealing is interpreted in terms of a dilation due to free carriers and a (smaller) contraction due to the Si atomic size effects.
Evidence for Vacancy Clustering in Silicon Implanted Indium Phosphide
Authors: Schultz Peter J. , Simpson P.J. , Akano U.G. , Mitchell I.V.
Published: March 2011

Damage induced in InP wafers by ion implantation has been investigated using Doppler broadening of annihilation radiation from variable-energy positrons (VEP), Rutherford backscattering/channeling (RBS), and room temperature photoluminescence (PL). Si* ions were implanted at 600 keV incident energy to total fluences from 1011 to 1014 ions cm−2. Annealing at room temperature was monitored for ∼100 days, during which both VEP and RBS showed recovery of the crystal toward the pre–implanted condition. RBS measurements of samples annealed at elevated temperatures showed that full restoration of lattice order occurred at 375 K, but VEP data for isochronal annealing up to 720 K showed only a moderate reduction in the vacancy–type defect concentration with a significantly narrower lineshape, consistent with vacancy clustering. PL measurements for MOCVD grown InP layers annealed up to 1100 K after implantation also indicated only moderate defect reduction.
Low Energy Ion Beam Modification of AlNxOy Thin Film for Insulated Gate Field Effect Transistors
Authors: Chan James S. , Cheung Nathan W. , Yu Kin Man
Published: March 2011

Nitrogen ion implantation was performed to enhance the nitrogen content of non-stoichiometric AlNXOY film (x < 1.0), which was prepared via reactive RF sputtering. A method called plasma immersion ion implantation (P111) was employed to perform the nitrogen implants. The implanted films were studied for changes in film composition using Rutherford Backscattering (RBS). Optical absorption behavior of the films was analyzed using a Perkin-Elmer monochrometer, and electrical characteristics were measured using both high frequency capacitance-volltage (CV) and current-voltage (IV) measurements. The implanted films were subsequently rapid thermal annealed in a nitrogen atmosphere from 550°C to 1060°C, and the resulting effects on the AlNXOY film were investigated using the aforementioned techniques.
Titanium Surface Hardening by Pulsed Nitrogen Ion Implantation
Authors: Feugeas Jorge , Sanchez G. , Grigioni G. , de Gonzalez C.O.
Published: March 2011

Layers of TiN have been developed on pure titanium samples using pulsed ion beams generated with a Plasma Gun operated in the detonation mode.

XPS analyses show TiNx formation in depths >0.6μm, with stoichiometric x>0.8. The efficient TiN formation in this process can be attributed to the fast energy released by the pulsed beams, which can increase the surface layer temperatures at a ∼15K/ns rate, generating thermal gradients of ∼1500K/μm. This thermal effect can help the titanium getter effect on the nitrogen plasma bubble.
Oxide Degradation Effects in Dry Patterning of Resist Using Neutral Oxygen Beams
Authors: Mlynko Walter E. , Kasi Srinandan R. , Manos Dennis M.
Published: March 2011

Novel processing methods are being studied to address the highly selective and directional etch requirements of the ULSI manufacturing era; neutral molecular and atomic beams are two promising candidates. In this study, the potential of 5 eV neutral atomic oxygen beams for dry development of photoresist is demonstrated for application in patterning of CMOS devices. The patterning of photoresist directly on polysilicon gate layers enables the use of a self-contained dry processing strategy, with oxygen beams for resist etching and chlorine beams for polysilicon etching. Exposure to such reactive low-energy species and to the UV radiation from the line-of-sight, high-density plasma source can, however, alter MOSFET gate oxide quality, impacting device performance and reliability. We have studied this process-related device integrity issue by subjecting polysilicon gate MOS structures to exposure treatments of 5–20 eV oxygen beams similar to those used for resist patterning. Electrical characterization shows a significant increase in the oxide trapped charge (30–90x) and interface state density (30–60x) upon low-energy exposure. Current-voltage(IV) and dielectric breakdown characterization show increased low-field leakage characteristics for the same exposure. High-field electron injection studies reveal that the 0.25–V to 0.5–V negative flatband shifts (measured after oxygen beam exposure) can be partially annealed by carrier injection. This could be due to positive charge annihilation or electron trapping, or some combination of both. SEM and electrical analysis of structures exposed to neutral beam processing are presented along with the results of thermal annealing treatments.
Formation of Defects During Ion-Assisted Growth of Thin Films from the Vapor Phase
Authors: Sundgren J-E , Hultman L , Håkansson G , Birch J , Petrov I
Published: March 2011

During ion-assisted growth of thin films from the vapor phase, defect generation and incorporation are of paramount interest. In many cases the wish is to obtain as defect free films as possible, however, in some applications a certain, controllable, defect content is desirable. In this paper experimental results on defect incorporation as a function of ion energy and growth temperature are presented. Results for poly- and single crystalline TiN films as well as for epitaxial Mo/V superlattice films are given. As the ion energy and/or ion flux are increased the amount of defects increases. At low temperatures the defects consist predominantly of point defect clusters and incorporated primary ions while at higher temperatures redistribution of point defects and incorporated primary ions results in dislocation loops and gas bubbles, respectively. However, for low ion energies where the energy transferred to the growing film surface is not high enough to cause atomic displacement events, reduction of defect densities can also be obtained. Furthermore, in the case of Mo/V superlattices it is demonstrated that interfacial mixing and increased interface roughness occurs at ion energies ≥ 25 eV. In the absence of an applied substrate bias the interface widths are determined to be 0.3 nm. For higher energies the widths becomes progressively larger and at a bias of 225 V an interface width of > 0.9 rum is obtained.
Role of Kinetic Energy of Sputtered Particles in Thin Film Properties
Authors: Taga Yasunori
Published: March 2011

The thin film processes of the sputter deposition method have been reviewed with special emphasis on the effects of kinetic energy of sputtered particles and ion bombardment during deposition on thin film properties. An overview is first given to describe the thin film process and ion-surface interactions, where the methods of measuring the energy distribution of sputtered ions and the anisotropic-emission-effect sputter deposition are presented. Experimental results for Cr, SiO2 and Ni-Si-B films are presented, and the correlation between the structure and properties of the thin films is discussed. Research in modification of thin films by energetic atoms and ions is an exciting area of materials science in the future.
Ion-Induced Surface Modification of Alloys
Authors: Wiedersich H.
Published: March 2011

In addition to the accumulation of the implanted species, a considerable number of processes can affect the composition of an alloy in the surface region during ion bombardment. Collisions of energetic ions with atoms of the alloy induce local rearrangement of atoms by displacements, replacement sequences and by spontaneous migration and recombination of defects within cascades. Point defects form clusters, voids, dislocation loops and networks. Preferential sputtering of elements changes the composition of the surface. At temperatures sufficient for thermal migration of point defects, radiation-enhanced diffusion promotes alloy component redistribution within and beyond the damage layer. Fluxes of interstitials and vacancies toward the surface and into the interior of the target induces fluxes of alloying elements leading to depthdependent compositional changes. Moreover, Gibbsian surface segregation may affect the preferential loss of alloy components by sputtering when the kinetics of equilibration of the surface composition becomes competitive with the sputtering rate. Temperature, time, current density and ion energy can be used to influence the individual processes contributing to compositional changes and, thus, produce a rich variety of composition profiles near surfaces.
Second Phase Formation in Aluminum annealed after Ion Implantation with Molybdenum.
Authors: Bentley J. , Stephenson L. D. , Benson R. B. , Parrish P. A. , Hirvonen J. K.
Published: March 2011

The microstructure of aluminum annealed after implantation to peak concentrations of approximately 4.4 and 11 at. % Mo was investigated by analytical electron microscopy. Al12Mo precipitates formed with pseudo-lamellar and continuous film microstructures. Video recordings of insitu annealing experiments revealed the details of the phase transformations.
High-Density Cascade Effects in Ion-Implanted Ag-Au Alloy
Authors: Vozzo F. R.
Published: March 2011

High-purity, polycrystalline foils of 12 atomic percent gold Ag-Au alloy were implanted with polyatomic ions of arsenic and antimony at energies of 45 keV per atom. During fluence intervals before and after the steady state, sputtered material was collected on high-purity strips of aluminum foil. Subsequent backscattering analysis of the targets and collectors showed that significant redistribution and segregation occurred in the implanted layer, with relative depletion of silver consistently observed. The results suggested that preferentiality in sputtering is dependent on composition of an alloy and the ion beam used (even at low fluence), but there appears to be no major difference between the redistribution behavior of targets sputtered with atomic ions and equal-velocity molecular ions.

A model is presented which predicts the sputtering behavior and surface configuration of a binary alloy implanted to steady state with a third species.
Ion Induced Morphological Instabilities in Ge
Authors: Appleton B. R.
Published: March 2011

The characteristics of an anomalous morphological instability initiated in amorphous Ge by heavy ion bombardment are reviewed and a model based on defect-production/defect-interactions is proposed.
The Production of Porous Structures on Si, Ge and GaAs by High Dose Ion Implantation.
Authors: Williams J.S. , Chivers D.J. , Elliman R.G. , Johnson S.T. , Lawson E.M. , Mitchell I.V. , Orrman-Rossiter K.G. , Pogany A.P. , Short K.T.
Published: March 2011

This paper presents new data on the previously observed porous structures which can be developed in high dose, ion implanted Ge. In addition, we provide strong evidence to suggest that such porous structures can be formed in high dose, ion implanted Si and GaAs substrates under particular implant conditions. Comparison of the various systems using RBS analysis indicates that heavy ion doses as low as 1014 cm−2 can give rise to such structural modifications in GaAs, whereas doses of 1015 cm−2 are needed to observe an effect with Ge and doses usually exceeding 1016cm−2 are required for Si.
Thermodynamics and Kinetics of Crystallization of Amorphous Si and Ge Produced by Ion Implantation
Authors: Donovan E.P. , Spaepen F. , Turnbull D. , Poate J.M. , Jacobson D.C.
Published: March 2011

Amorphous Si and Ge layers, produced by noble gas (Ar or Xe) implantation of single crystal substrates, have been crystallized in a differential scanning calorimeter (DSC). This technique allows determination of the growth velocity (which is proportional to the rate of heat evolution, ΔHac), and the total enthalpy of crystallization ΔHacAmorphous Ge was found to relax continuously to an amorphous state of lower free energy, with a total enthalpy of relaxation of 6.0 kJ.mole−1 before crystallization started. The regrowth velocity on (100) substrates,measured to be 4.2×1017 exp (−2.17eV/kT)Å/sec, is compared to other determinations. The value of ΔHac was found to be 11.66± 0.7 kJ.mole, in good agreement with ΔHac for amorphous Ge produced by other methods. For Si, ΔHac was determined to be 11.95± 0.7 kJ.mole without any evidence of heat release due to relaxation. The kinetics of crystallization measured by DSC are compared with those determined by other techniques. The effects of the implant profile on the regrowth velocity could also be observed directly in the DSC signal. The more accurate value of ΔHac allowed a more precise determination of the melting temperature of amorphous Si: Taℓ= 1420K.
Physical Properties of Two Metastable States of Amorphous Silicon
Authors: Hubler G.K. , Waddell C.N. , Spitzer W.G. , Fredrickson J.E. , Kennedy T.A.
Published: March 2011

Characterization of the two metastable states of amorphous Si produced by ion implantation is extended to include electron paramagnetic resonance, fundamental absorption edge, and density measurements in addition to infrared reflection. It is found that the properties of the two a-Si states are not dependent upon the mass of the incident ion (12C, 29Si, 31p, 120Sn) or upon the anneal temperature for 400°≤TA≤600°C. The dangling-bond density drops about a factor of 2, the absorption coefficient drops by more than a factor of 5, but the density does not change when the a-Si makes a transition between the two states.
Megavolt Bioron and Arsenic Implantation into Silicon
Authors: Byrne P.F. , Cheung N.W. , Tam S. , Hu C. , Shib Y.C. , Washburn J. , Strathman M.
Published: March 2011

Formation of buried p-type and n-type layers in (100) silicon has been accomplished by implanting with 4 MeV boron and 11 MeV arsenic ions respectively. The projected range (Rp) of 4 MeV boron is 5.2 microns with a straggle (ΔRp) of .2 microns. The 11 MeV arsenic implant has a Rp of 4.37 microns with a ΔRp of .37 microns. The 4 MeV boron implant was carried out to a dose of l×1015/ cm2 while the 11 MeV arsenic implant dose was 1.9×1015/ cm2. For both dopants the target holder could be cooled with either liquid nitrogen (LN) or flowing room temperature water (RT). Buried amorphous regions are seen by cross sectional transmission electron microscopy (XTEM) for both boron and arsenic when LN cooling is used. Arsenic shows a buried amorphous region for the RT case as well. The extent of the buried amorphous regions are compared with the energy deposited into nuclear stopping as determined by computer simulation. Threshold levels are determined for the creation of these buried amorphous regions. The boron samples were annealed for 30 minutes at 900°C in a nitrogen ambient, and XTEM shows no residual damage for both cooling conditions. The arsenic samples underwent a two step annealing procedure; 545°C for 16 hours followed by a 945°C step for 15 minutes. Regions containing dislocation networks are observed by XTEM for both cooling conditions.

The 4 MeV implanted boron buried layer was applied to an NMOS process. Transistors fabricated above the p-type buried layer show channel mobility, threshold voltage, and sub-threshold leakage which are indistinguishable from transistors fabricated without the buried layer. Vertical npn bipolar transistors have been fabricated using the 11 MeV arsenic buried layer to form the collector. Electrical characteristics from both these devices indicate that megavolt ion implantation can be applied to silicon for active device geometries.
A Review of Silicon-On-Insulator Formation by Oxygen Ion Implantation
Authors: Pinizzotto Russell F.
Published: March 2011

Silicon-on-Insulator structures will be an important technological advance used in future VLSI, VHSIC and threedimensional integrated circuits. The most mature SOI technology other than silicon-on-sapphire is SIMOX, or Separation by Implanted Oxygen. High energy oxygen ions are implanted into single crystal silicon until a stoichiometric buried silicon dioxide layer is formed. After implantation, the material is annealed at high temperature to remove implantation induced defects. The structure is completed by the growth of a thin epitaxial silicon layer. Devices and complex circuits have been successfully fabricated by several research groups. This paper reviews the development of this buried oxide SOI technology from 1973 to 1983. The five major sections discuss the advantages of SOI, the basics of buried oxide formation, the literature published between 1973 and 1983, key issues that must be solved before large scale implementation takes place and, finally, predictions of future developments.
Characterisation of Device Grade Soi Structures formed by Implantation of High Doses of Oxygen
Authors: Hemment P.L.F. , Maydell-Ondrusz E.A. , Stephens K.G. , Arrowsmith R.P. , Glaccum A.C. , Kilner J.A. , Butcher J.B.
Published: March 2011

SOI structures have been formed in (100) silicon by implanting 400 keV molecular oxygen to a dose of l.8×l018 O atoms cm−2. These samples were annealed at 1150°C for 2 hours with a SILOX cap. Oxygen depth profiles have been determined by SIMS and wafers implanted at about 500°C have been characterized by studying the regrowth kinetics, As drive in and oxidation rate in the top silicon overlay.
Point defect Supersaturation and Enhanced Diffusion in SPE Regrown Silicon.
Authors: Pennycook S. J. , Narayan J. , Holland O. W.
Published: March 2011

Transient, greatly enhanced diffusion has been observed on annealing solid-phase-epitaxial (SPE) grown Si-Sb alloys. This is shown to be due to a high concentration of interstitials being trapped during SPE regrowth. The migration enthalpy, for diffusion of Sb by an interstitialcy mechanism was measured as 1.8 ± 0.2 eV. The interstitials eventually condensed into loops, marking the end of the transient. In a SPE grown Si-Bi alloy a similar transient enhanced diffusion was observed, with an activation energy of 2.0 ± 0.2 eV, but no loops formed.
Investigation of a Thermal Spike Model for Ion Mixing of Metals with SI
Authors: Shreter U. , So Frank C.T. , Paine B. M. , Nicolet M-A.
Published: March 2011

A Model for Ion Mixing of Bilayer systems in a thermal spike is described. Normal thermal reactions, at a constant average temperature, are assumed for the duration of the spike. New experimental results on mixing of a Nb/Si couple with Xe ions are shown to agree with the prediction of the model that the apparent activation energy in ion mixing can depend upon the ion species. Calculations of spike mixing for Cr and Ni with Si are presented which show that a substantial part of the experimentally observed mixing rates, and their temperature dependence, can be attributed to thermal spike effects.
Comparison of Heat-Pulse and Furnace Isothermal Anneals of Be Implanted InP
Authors: Molnar B. , Kelner G. , Ramseyer G.L. , Morrison G.H. , Shatas S. C.
Published: March 2011

Annealing in the 600–900°C temperature range, using either a halogen lamp for periods of seconds or a furnace for periods of minutes, has been applied to activate Be implanted InP samples. The Be was ion-implanted at room temperature into InP substrates. The substrates were uncapped and in close contact with another smooth surface during annealing.

It was found that in the 1017–1019/cm3 range, the acceptor concentration increased with the temperature of anneal. It was also found that redistribution effects decreased with decreasing anneal time. For short anneals, the optimum condition for an 80–90% activation in the 1017–1018/cm3 range was estimated to be 10 seconds at 950°C. It was also found that after rapid anneal, the carrier concentration profile closely approximated the asimplanted Be profile. In the case of 1018–1019/cm3 implants, which were rapidly annealed, there was a low concentration component (1016–1017/cm3) to the redistribution; this ancillary component to the main active distribution was detected by SIMS and was electrically inactive. For long term annealing this electrically inactive Be component was partly converted to substitutional Be and became electrically active. Rapid thermal annealing eliminated this conversion.
Study of Near Surface Structure and Composition for High Dose Implantation of Cr+ into Si
Authors: Namavar F. , Budnick J. I. , Hayden H. C. , Otter F. A. , Patarini V.
Published: March 2011

The dependence of the implanted layer composition on total dose, dose rate and target chamber environment for Cr+ implanted Si have been studied by means of Rutherford Back Scattering (RBS) and Auger Electron Spectroscopy (AES). Implantation of Cr+ for doses up to 2 × 1018 ions/cm2 and a fixed dose rate and energy were carried out in an ultra high vacuum (UHV) system as well as in a diffusion pumped vacuum (DPV) system. For the former, the maximum Cr concentration was about 42%. On the other hand, implantation of Cr in a DPV system resulted in a much higher peak concentration (86%) and retention.

Both the RBS and AES results positively demonstrate the existence of extensive surface carbon for a Si-rich surface and a chromium oxide layer for the Cr-rich surface. This result suggests that the interaction of oxygen or carbon occurs preferentially and depends on the surface composition.

No surface compositional variation could be observed by the RBS experiments for Cr implanted in a UHV system for different dose rates. In contrast, for implantation in a DPV system, higher concentrations can be achieved for lower dose rates.
Modification of μm Thick Surface Layers Using keV Ion Energies
Authors: Rehn L. E. , Lam N. Q. , Wiedersich H.
Published: March 2011

Root-mean-square diffusion distances for both vacancy and interstitial defects in metals can be very large at elevated temperatures, e.g. several μm's in one second at 500°C. Consequently, defects that escape the implanted region at elevated temperature can produce compositional and microstructural changes to depths which are much larger than the ion range. Because of the high defect mobilities, and of the fact that diffusion processes must compete with the rate of surface recession, the effects of defect production (ballistic mixing), radiation-enhanced diffusion and radiation- induced segregation become spatially separated during ion bombardment at elevated temperature. Results of such experimental studies in a Cu-Ni alloy are presented, discussed and compared with predictions of a phenomenological model. Contributions to the subsurface compositional changes from radiation-enhanced diffusion and radiation- induced segregation are clearly identified.
Ion Beam Modification of Ceramics
Authors: Mchargue C. J. , White C. W. , Appleton B. R. , Farlow G. C. , Williams J. M.
Published: March 2011

Alterations to the structure and properties of ceramics are complex due to the range of bonding types encountered and the necessity for maintaining local charge balance. Ion damage can occur as a result of ionizing effects as well as displacement collisions. Ion species, implantation temperature, implantation energy, and the specific bonding characteristics of the host are important parameters in determining the structure and properties of implanted ceramics. Some of these effects will be illustrated for Al2O3 implanted with chromium or zirconium and silicon carbide implanted with chromium.
Changing the Indentation Behaviour of MgO by Ion Implantation
Authors: Burnett P.J. , Page T.F.
Published: March 2011

Cleaved {100} MgO single crystal surfaces have been implanted with 300keV Ti+and Cr+ ions to doses in the range 10 16 −1018 ions cm−2. Localised plasticity and fracture behaviour has been investigated using microhardness indentation tests at loads of between 10gf and 500gf.Significant surface hardening has been observed at lower doses with amorphisation related softening occurring at higher doses. Post-implantation heat treatments produce precipitation reactions with associated hardness changes.
Synthesis of Hard Si-C Composite Films by Ion Beam Irradiation of Polymer Films
Authors: Venkatesan T. , Wolf T. , Allara D. , Wilkens B. J. , Taylor G. N. , Foti G.
Published: March 2011

We propcoe a novel technique to convert polymer films into useful inorganic films by ion beam irradiation. Along the track of an ion the polymer is dissociated into smaller fragments. volatile fragments diffuse through the film and escape. Any element which is not removed in the form of volatile species is subsequently enriched with respect to the other elements. We demonstrate this effect in a polymer poly(dimethylsilylene-co-methylphenylsilylene), which initially has a C:Si ratio of 45:1. Upon irradiation with 2 MeV Ar+ ions at a dose of 1015 ions/cm2 the C:Si ratio changes to 3.4:1 as verified by Rutherford backscattering spectrometry. We believe that the effect of the ion beam irradiation is to produce more Si-C bonds at the expeme of the C-H and Si-Si bonds, with ≲10% of the original hydrogen being present in the film at high doses. The loss of the H atoms is further confirmed by a nuclear reaction technique. The IR spectra of the film as a function of the irradiation dose shows a progressive loss of fine molecular features with significant increase of the refractive index. The IR spectrum at the high doses appears to be due to a mixture of various Si and C bonds. However, the irradiated films are very hard and scratch resistant (knoop value ≳1300) suggesting an increase in the number of silicon carbide bonds
Depth Profiling of Hydrogen in Ion-Implanted Polymers
Authors: David Carlson J. , Pronko Peter P. , Ingram David C.
Published: March 2011

Depth profiling of hydrogen in polymeric materials poses special problems. Backscattering methods are ruled out because of kinematics. Nuclear reaction methods are undesirable because small reaction cross sections necessitate large fluences of high mass projectiles and result in unacceptable levels of radiation damage. We have used a helium-induced proton-recoil technique with 3 MeV 4He particles to measure the hydrogen distribution in pristine and ion-implanted polyvinylidene fluoride (PVDF) films. The incident 4He particles stopped in the 25 micron PVDF films while the recoiling protons were detected after passing through the polymer film. Large changes in the hydrogen content of PVDF films implanted with modest fluences of 6 MeV carbon, oxygen and nickel ions were observed.
Ion Beam Mixing Effects in Au-Fe and Pt-Fe Thin Bilayers
Authors: Battaglin G. , Carnera A. , Celotti G. , Della Mea G. , Kulkarni V.N. , Lo Russo S. , Mazzoldi P.
Published: March 2011

Mixing effects induced by Kr++ bombardment in the Au-Fe and Pt-Fe metallic systems have been studied by Rutherford backscattering and X-ray diffraction techniques. The mixed amount of Fe atoms shows a linear dependence on the square root of the Kr do se for both systems. The induced mixing appears more efficient for the Pt-Fe with respect to the Au-Fe system. In the case of Pt-Fe mixing is much more efficient when the initial bilayer structure has Pt on the top. The X-ray diffraction analysis reveals the formation of an extended solid solution of Fe in Pt, having the Fe40 Pt60 composition.
Development of New Materials by Ionized-Cluster Beam Technique
Authors: Takagi T.
Published: March 2011

In the Ionized-Cluster Beam (ICB) technique, deposition by macroaggregates consisting of 500 to 2000 atoms loosely coupled together involves low ratios of charge to mass. Consequently, high mass density beams at low equivalent energy per atom in an optimum range for film formation can be transported without problems due to space charge repulsion forces and deposition onto insulating substrates is easily possible due to low accumulation of ion charge. The presence of ionic charge has great influence upon film formation mechanisms in spite of low content of ions in the total flux. Also, because of the kinetics of cluster breakup upon impact, enhancement of migration of adatoms upon a substrate surface can be achieved by increasing the acceleration voltage. It is possible to control the mechanical, crystallographic, optical and magnetic properties of films over three dimensions by variation of acceleration voltage or ion content in the total flux. Films of many materials have been formed at low temperatures with well-controlled characteristics. Among examples of interest are included metal and semiconductor material films for functional devices and VLSI applications, intermetallic compound films for magnetic or thermoelectric uses and organic material films. Results suggest that ICB offers exceptional potential for applications involving formation of new materials.
Ion Beam Irradiation of Metal Films on SiO2
Authors: Clark G. J. , Baglin J. E. E. , d'Heurle F. M. , White C. W. , Farlow G. , Narayan J.
Published: March 2011

Ion beam irradiation of metal film/SiO2 interfaces causes reactions when the metals are those chemically capable of reducing SiO2. These reactions result in the formation of metal rich silicides in the region of the interface and an increase in the adhesion of the film to the substrate. For other nonreactive metals ion irradiation causes lateral transport of metal atoms resulting in the formation of an island structure. The results obtained by ion irradiation are compared with previous studies of high temperature thermal processing of metal films on SiO2.
Magnetoreflection of Ion-Implanted Bismuth
Authors: Kunoff E. M. , Elman B. S. , Dresselhaus M. S.
Published: March 2011

Bi single crystals have been implanted with isoelectronic ions (As, Sb and Bi) and the electronic structur of these implanted materials has been studied using the magnetoreflection technique. Since the ion penetration depth and optical skin depths are of roughly the same magnitude, this technique provides a sensitive test for implantation-induced changes in the electronic structure. Explicitly, the magnetoreflection spectra show changes in lineshape, resonant frequency and in some cases the introduction of Landau level transitions forbidden in unimplanted bismuth. In particular, implantation-induced changes in the resonance lineshapes indicate an increase in plasma frequency as either the fluence of the implants or the ion size is increased. Further analysis of the data shows that the Lax model, which accounts for the magnetoreflection spectra of unimplanted bismuth, is equally applicable to bismuth implanted with isoelectronic ions. Our results yield measurable changes in the L-point band gap and smaller relative changes in the band parameter combination Eg/m* . The mechanism responsible for these changes in the electronic structure of bismuth is suggested.
Enhancement in Adhesion of Pt Films on Ceramics by Helium Ion and Electron Irradiation, and a Study of their Electrochemical Behaviour.
Authors: Sood D.K. , Bond P.D. , Badwal S.P.S.
Published: March 2011

The adhesion of Pt films (10–330nm thick) sputter deposited on prepared substrates of yttria stabilized zirconia (YSZ) and alumina has been observed to be remarkably enhanced after irradiation with 2 MeV He++ ions and 5–30 keV electrons. The adhesion enhancement has been studied as a function ot beam energy, dose and film thickness. Thermal stability of adhesion enhancement and of the microstructure of ‘stitched’ films has been investigated. The electrochemical behaviour of ‘stitched’ Pt electrodes on YSZ has been studied by complex impedance spectroscopy.
Ion Implantation into Nb/NbO/PbAuIn Josephson Tunnel Junctions
Authors: Clark G. J. , Raider S. I.
Published: March 2011

Boron ions were implanted into completed planar and edge Nb/Nb oxide/PbAuIn Josephson tunnel junctions to directly trim the Josephson pair currents, Io. The implantation caused an increase in Io and in the junction subgap conductance and a decrease in the junction energy gap. For a fixed junction fabrication procedure, the variations were observed to be monotonic with 11B implant dose. Optimum trimming was found when the 11B ions were implanted such that the peak in the depth distribution occurred at the tunnel barrier. The implantation caused an increase in Io and in the junction subgap conductance and a decrease in the junction energy gap. The implanted junctions are stable at 80°C and under storage.
Tribomechanical Properties of Ion Implanted Metals
Authors: Singer Irwin L.
Published: March 2011

A review of tribomechanical studies supported by surface analysis finds ion implantation capable of increasing the sliding wear resistance of ion implanted metals in two ways. First, it can reduce friction by modifying the surface composition (e.g. Ti+ into steel) or by promoting the growth of low friction oxide layers (e.g. N into Ti). Second, it can modify the subsurface composition and structure to resist fracture and debris formation. These modifications harden the surface, change its work-hardening behavior and/or increase residual stresses. Microindentation hardness measurements indicate that many but not all of the wear resistant surfaces are hardened by implantation; thus, surface hardness is a contributing but not necessarily a controlling factor in wear resistance. These mechanisms of wear reduction and the chemical and microstructural modifications responsible for them are discussed. Evidence for wear reduction through the migration of N during wear is critically reviewed. It is concluded that the principal benefit of ion implantation is to prevent or delay the formation of wear particles, thereby changing the wear mode during run-in and permitting metals to reach load-carrying capacities up to their elastic limits.
Hardness as a Measure of Wear Resistance
Authors: Oliver W.C. , Hutchings R. , Pethica J.B. , Singer I.L. , Hubler G.K.
Published: March 2011

One measure of the surface mechanical properties of materials can be obtained through microhardness data. The success of microhardness in predicting the improvements in wear resistance of ion implanted metals has been mixed. In this paper the cases of N implantation into 304 S.S. and Ti implantation into 52100 bearing steel will be examined. Microhardness data indicates little or no hardness changes whereas large wear rate changes are observed. From these two examples it is clear that the wear mechanism, the chemical nature of the surface, the ductility, and the toughness can be more important than the hardness changes.
Modeling of High Fluence Titanium Ion Implantation and Vacuum Carburization in Steel
Authors: Farkas D. , Singer I. L. , Rangaswamy M.
Published: March 2011

Concentration vs. depth profiles have been calculated for Ti and C in 52100 Ti-implanted steel. A computer formalism was developed to account for diffusion and mixing processes, as well as sputtering and lattice dilation. A Gaussian distribution of Ti was assumed to be incorporated at each time interval. The effects of sputtering and lattice dilation were then included by means of an appropriate coordinate transformation. C was assumed to be gettered from the vacuum system in a one-to-one ratio with the surface Ti concentration up to a saturation point. Both Ti and C were allowed to diffuse. A series of experimental (Auger) concentration vs. depth profiles of Ti implanted steel were analyzed using the above-mentioned assumptions. A best fit procedure for these curves yielded information on the values of the sputtering yield, range and straggling, as well as the mixing processes that occur during the implantation. The observed values are in excellent agreement with the values predicted by existing theories.
Microstructures of Stainless Steels Exhibiting Reduced Friction and Wear After Implantation with Ti and C
Authors: Follstaedt D. M. , Yost F. G. , Pope L.E.
Published: March 2011

Implantation of Ti and C into stainless steel discs of Types 304, 15–5 PH, Nitronic 60 and 440C has previously been reported to reduce wear depths by up to ∼ 85% and friction by ∼ 50% in unlubricated pin-on-disc tests. Our earlier studies relating microstructure to friction and wear results in Type 304 are first summarized; these indicate that the improvements in the surface mechanical properties are due to an amorphous surface layer, similar to the amorphous layer observed in pure Fe implanted with Ti and C. We have now examined the other three implanted steels and found similar amorphous layers. These results strongly suggest that the amorphous surface alloy is responsible for reduced friction and wear in all the steels.
Friction and Wear Reduction of 440C Stainless Steel by Ion Implantation
Authors: Pope L. E. , Yost F. G. , Follstaedt D. M. , Picraux S.T. , Knapp J. A.
Published: March 2011

Friction and wear tests on ion-implanted 440C stainless steel discs have been extended to high Hertzian stresses (≤ 3150 MPa). Implantation of 2 × 1015 Ti/mm2 (180–90 keV) and 2 × 1015 C/mm2 (30 keV) into 440C reduces friction (∼40%) and wear (> 80%) for Hertzian stresses as large as 2900 MPa, stresses which significantly exceed the yield strength of 440C (∼1840 MPa). Implantation of 4 × 1015 N/mm2 (50 keV) into 440C reduces friction slightly (∼25%) for Hertzian stresses > 1840 MPa but provides little or no reduction in wear. The amount of Ti remaining in the wear tracks correlates with the reductions in friction and wear. The implantation of Ti and C produces an amorphous surface layer which is believed to reduce friction and wear, whereas N implantation is expected to produce hard nitride particles which probably do not modify the hardness of 440C (KHN = 789) significantly.
Friction, Wear and Deformation of Soft Steels Implanted with Ti and N
Authors: Singer I.L. , Jeffries R.A.
Published: March 2011

Friction and wear measurements were performed with a hardened steel ball sliding against unhardened steels (AISI 10184 304 and M2) implanted with either N+ or Ti+ or both N+ Ti+ ions. Dry and lubricated sliding studies found that: Ti-implantation reduced friction and thereby delayed wear; N-implantation did not reduce friction but delayed wear by increasing the resistance of the surface to shear; and dual implants of N+ + Ti+ showed effects of both implants. Auger sputter depth profiles found the 1018 and M2 surfaces enriched in implanted N and bulk C. No evidence of N migration could be found in heavily deformed surfaces.
Electrical Resistivity of Multilayers During Ion Beam Mixing
Authors: Grilhe J. , Riviere J.P. , Delafond J. , Jaouen C. , Templier C.
Published: March 2011

A new approach is developed, employing “in situ” electrical resistivity measurements, as a tool to study ion beam mixing of evaporated metal-metal multi or bilayers. The electrical resistivity variations measured continuously during the ion bombardment exhibit a monotonical increase and a tendency toward a saturation process allowing to detect precisely the total mixing of the film. The volume fraction of intermixed atoms can be determined within the framework of a simple conduction model. Experimental results are given in the case of Fe-Al and Al-Ag multilayers.
Wear Improvement in Ti-6Al-4V by Ion Implantation
Authors: Vardiman R.G.
Published: March 2011

The friction and wear of Ti-6Al-4V are found to be sharply reduced by carbon implantation followed by heat treatment. Optimum wear resistance is developed at 400° C, at which the microstructure of the implanted layer shows a dense array of TiC precipitates up to 60 nm in size. The implanted layer in this case is worn through in a few thousand cycles of the ball on disc test, but by implanting at two energies to achieve a deeper carbide layer, negligible wear was found even after 20,000 cycles. No wear improvement was found for nitrogen implantation.
Ion Implanted Ti-6Al-4V
Authors: Oliver W. C. , Hutchings R. , Pethica J. B. , Paradis E. L. , Shuskus A. J.
Published: March 2011

Titanium and many of its alloys show very poor wear resistance considering their hardness. This together with high thermodynamic driving forces to form very hard compounds between titanium and nitrogen or carbon made titanium based alloys obvious candidates for ion implantation. In this paper the effects of similar implanted concentration profiles of nitrogen and carbon in two titanium alloys are compared. The wear behavior of pin on disk wear tests are reported along with the ultramicrohardness of the four samples.
Effect of Cr+ Implantation on the Thermal Oxidation of Ta
Authors: Grabowski K.S. , Gossett C.R.
Published: March 2011

Cr+ implantation of Ta was undertaken in an attempt to improve oxidation resistance at temperatures between 500 and 750°C, and for oxidation times up to l00h. Samples were implanted with 1.5×1017 Cr+/cm2 at 150 keV, and compared to samples implanted with 1×l016 or 1×1017 Ta+/cm2 at 145 keV to evaluate the role of physical effects from ion implantation. Following oxidation, samples were examined using helium and proton backscattering, electron and optical imaging techniques, and auger electron spectroscopy. Improved resistance to oxidation was observed in Cr+-implanted samples oxidized at 500°C for up to l00h, and at 600°C for about lh. However, some local breakdown occurred in these samples and no protection at all was observed at 750°C. Reasons for this breakdown are discussed and alternate approaches for improving oxidation resistance using ion implantation are proposed.
Recoil Implantation of Ito thin Films on Glass Substrates
Authors: Rabin B. H. , Harbison B. B. , Shatynski S. R.
Published: March 2011

Indium-Tin Oxide (ITO) heat mirror films implanted into window glass were obtained by post annealing of argon irradiated coatings of In-5w/o Sn produced by reactive evaporation in oxygen. Characterization of coatings has been carried out using TEM and AES. Optical properties have also been evaluated. The production of acceptable thin films requires low energy deposition rates during ion bombardment. This places a limit on the extent of film-substrate mixing, which is required if increased film lifetimes are to be realized.
High Energy Ion Beam Mixing in Al2 O3
Authors: Lewis M. B. , Mchargue C. J.
Published: March 2011

The ion beam mixing technique has been employed to mix metal atoms into the surface layers of Al2O3. Ion beams of Fe+ and Zr+ in the 1 to 4 MeV energy range were used to irradiate Al2O3 specimens on the surfaces of which films of chromium or zirconium had been evaporated. Some specimens were irradiated at elevated temperatures of 873 or 1173 K. Rutherford backscattering (RBS) and channeling methods were used to measure the metal atom depth profiles near the surface. Analyses of the backscattering data included binary collision calculations using the codes TRIM and MARLOWE. The significance and limitations of high energy (>1 MeV) beams for ion beam mixing experiments is discussed. Evidence was found for radiation enhanced diffusion and/or solubility of zirconium and chromium in Al2O3 at 873 K.
Preparation of Strontium Titanate Powders by Decomposition of Polymeric Precursors
Authors: Peschke S. L. , Ciftcioglu M. , Doughty D. H. , Voigt J. A.
Published: March 2011

The effects of substituting poly(acrylic acid), PAA, and mucic acid for citric acid in the standard Pechini powder synthesis process was studied. Strontium titanate was chosen as the model system for this study. Powders were prepared from precursor solutions in which PAA (average molecular weight = 2,000 and 5000) was substituted for citric acid (up to 70% by weight), and with reduced weight of total organic reagents (50% reduction). The powders prepared with a 30% substitution of PAA for citric acid produced weakly agglomerated submicron particles after calcining. These powders contained a larger fraction of weak agglomerates than the powders prepared by the original Pechini process. As such, the PAA derived powder could be easily fractionated and dispersed with greater than 70% of the calcined powder having particle sizes less than 0.5 μm