bluuebunny/crossref_metadata_2025 huggingface dataset:
Theoretical Analysis of Homogeneity and Surface Degradation During Pulsed Electron Beam Annealing of GaAs and InP
Authors: Laugier A. , Barbier D. , Chemisky G.
Published: March 2011

PEBA induced thermal effects in GaAs and InP have been simulated. Monte-Carlo calculation has been used to determine universal electron energy loss functions in the 5–50 keV energy range for these materials. Similar electron depth-dose profiles of a polykinetic electron beam pulse is deduced in both GaAs and lnP. A simple adiabatic approach is sufficient to establish relationship between melting depths and fluences. Thermal effects homogeneity and surface degradation are discussed for both crystalline and amorphous materials using variable electron energy deposition profiles. Correlation is made between experimentally measured degradation thresholds and calculated fluence windows within which melting effects are expected.
Rapid Thermal Annealing of Composite TaSi2/n+ Poly-Si Silicide Films
Authors: Kwong D.L. , Kwor R. , Tsaur B.Y. , Daneshvar K.
Published: March 2011

The formation of composite TaSi2/n+ Poly-Si silicide films through the use of rapid thermal annealing (RTA) is investigated by x-ray diffraction, four point probe, scanning Auger microprobes (SAM) with ion sputter etching, transmission electron microscopy (TEM), scanning electron microscopy (SEM), and capacitance-voltage (C-V) measurements. 0.2 μm polysilicon is deposited on oxidized Si wafer by LPCVD and doped with phosphorus. A layer of 2200 A TaSix is then co-sputtered on polysilicon samples from separate targets. These as-deposited films are then annealed by RTA in an argon ambient for 1 sec. and 10 sec. at various temperatures. X-ray diffraction and SAM results show the rapid formation of a uniform stoichiometric tantalum disilicide via Si migration from polysilicon. TEM micrographs show simlilar results for samples annealed at 1000°C in furnace for 30 min. or by RTA for 1 sec., exhibiting average grain size greater than 1000 A. Sheet resistance of samples annealed by furnace annealing and RTA are comparable. SEM micrographs indicate that the surface morphology of the RTA-annealed sample is superior to that obtained by furnace annealing. These results show that RTA may offer a practical solution to low-resistivity silicide formation in VLSI circuits.
Annealing of High Dose C Implanted Si by Pulsed Electron Beam
Authors: Durupt P. , Barbier D. , Laugier A.
Published: March 2011

High dose (1–7 1017cm−2), low energy (10–40 keV) C implanted Si samples were annealed by conventional thermal procedure and by pulsed electron beam. Characterization is performed by I.R., electron diffraction and Rutherford Backscattering. Effect of PEBA is equivalent to thermal annealing at 900°C. No C redistribution occurs and a poor recrystallization of the SiC formed during implantation is observed.
Pulsed Laser Melting of Amorphous Silicon: Time-Resolved and Post-Irradiation Studies
Authors: Lowndes D. H. , Wood R. F. , White C. W. , Narayan J.
Published: March 2011

Measurements of the time of the onset of melting of self-implantation amorphized (a) Si, during an incident laser pulse, have been combined with modified melting model calculations and measurements of surface melt duration to demonstrate that the thermal conductivity, Ka, of a-Si is very low (≃0.02 W/cm-K). Ka is also shown to be the dominant parameter determining the dynamical response of ionimplanted Si to pulsed laser radiation; the latent heat and melting temperature of a-Si are relatively unimportant. Cross-sectional transmission electron micrographs on implantation-amorphized Si layers of several different thicknesses show that for energy densities less than the threshold value for complete annealing there are usually two distinct regions in the re-solidified a-Si, consisting of fine-grained and large-grained polycrystalline Si, respectively. The presence of the fine-grained poly-Si suggests that bulk nucleation occurs directly from the highly undercooled liquid phase. Thermal melting model calculations suggest that the nucleation temperature, Tn is ≃1200°C.
Secondary Grain Growth in Heavily Doped Polysilicon During Rapid Thermal Annealing
Authors: Batra S. , Park K. , Lobo M. , Banerjee S.
Published: March 2011

To successfully implement Silicon-on-Insulator (SOI) technology using polysilicon-on-oxide, it is necessary to maximize the grain size such that the active devices are entirely within very large single crystal grains. A drastic increase in grain size in polysilicon has been reported due to secondary grain growth in ultra-thin, heavily n-type doped films upon regular furnace annealing. Very little work has been undertaken, however, to study secondary grain growth during Rapid Thermal Annealing (RTA).This paper is a study of the grain growth mechanism in heavily P-doped, amorphous silicon films during RTA. Secondary grains as large as 16 μm have been obtained in 160 nm thick films after a 180 s RTA at 1200 °C, representing a grainsize- to-film-thickness-ratio of 100:1. This is the largest secondary grain size and grain-size-to-film-thickness reported in the literature. A detailed analysis of negatively charged silicon vacancies has also been employed to explain the lower activation energy (1.55 eV) of secondary grain growth compared to that of normal grain growth (2.4 eV).
Raman Studies of Stress-Induced Phase Transformations in Titania Films
Authors: Exarhos Gregory J. , Hess Nancy J.
Published: March 2011

Time-resolved micro-Raman spectroscopy is used to follow the amorphous to crystalline phase transformation in sol-gel deposited titania films induced thermally or through the action of applied hydrostatic pressure in a diamond anvil cell. Time-dependent phonon intensities intrinsic to the growing phase are related to the volume fraction of crystallite present at any time. The sigmoidally generated curves can be modeled in terms of modified Avrami ingrowth kinetics in which diffusion of the amorphous phase to the nucleation center is restricted by the morphology of the evolving phase. Phonon frequency and linewidth measurements during the course of the transformation probe changes in film stress and particle size which are used to understand the mechanistics of the transformation. Raman measurements also are used to derive a phase stability diagram for titania films.
Oscillatory Interlayer Exchange Coupling Through Cu and Various Transition Metals
Authors: Parkin S.S.P.
Published: March 2011

We show that oscillatory interlayer exchange coupling of thin magnetic layers through metals is a general phenomenon present in almost all the transition and noble metals. Surprisingly the period of the oscillations is approximately the same, about 10Å, in all these metals with the sole exception of Cr for which the period is significantly longer. The strength of the coupling varies systematically throughout the 3d, 4d and 5d transition metals increasing exponentially along each of the transition metal periods and increasing from the 5d to 4d to 3d periods. These results appear to be inconsistent with simple Ruderman-Kittel-Kasuya-Yosida (RKKY) based models.
Theory of Oscillatory Exchange Between Magnetic Layers Through a Nonmagnetic Transition–Metal Spacer
Authors: Mathon J.
Published: March 2011

A general theory of oscillations in the exchange coupling between two transition metal ferromagnets separated by a nonmagnetic transition metal spacer is developed. A close analogy between oscillations in the exchange coupling and de Haas-van Alphen oscillations is established and exploited to show that the period, asymptotic decay, and temperature dependence of the oscillations are determined by properties of the d band Fermi surface in the spacer layer. The theory accounts qualitatively and even semiquantitatively for all the salient experimental features of the oscillations in the exchange coupling observed recently in Co/Ru, Co/Cr, and Fe/Cr superlattices.
Epitaxial Co-Cu Superlattices
Authors: Schuler Elizabeth , Elagoz Sezai , Vavra William , Lamelas Frank , He Hui David , Clarke Roy
Published: March 2011

We describe measurements on the magnetic properties of Co-Cu superlattices in which the Co layer thickness was fixed at 20 Å and the Cu thickness was varied from 4 Å to 24 Å. The samples were grown on Ge-buffered (110) GaAs by molecular beam epitaxy. X-ray scattering and in-situ RHEED indicate that the multilayers are oriented in the (111) direction with the Co layers stacked in an fcc arrangement. Our interest in this series of samples lies in their unusual hysteresis curves which show distinct transitions. We have found that the appearance of these transitions is directly related to the Cu thickness, indicating the presence of complex spin configurations as a consequence of competing interactions. The results are not consistent with a simple RKKY antiferromagnetic coupling.
Stepped Fe(100) and V/Fe(100) Magnetism
Authors: Vega A. , Rubio A. , Balbas L.C. , Dorantes-Davila J. , Demangeat C. , Mokrani A. , Dreysse H.
Published: March 2011

We have investigated the magnetic arrangment of 3d transition-metal stepped surface by using a self-consistent real-space tight-binding method. As expected, the presence of steps modifies locally the properties of a transition-metal surface. We emphasized the influence of atomic environment. We found for the (100)-Fe surface, an enhancement of the magnetic moments of the external edge of this step as compared to the flat surface. The results are not very sensitives to the step length. More striking is the case of the (100)-V stepped surface where atoms at the external edge display a large magnetic moment.
Investigation of Magnetic Order in Iron Oxide-Nickel Oxide Superlattices with Modulation Wavelength Less Than 80 Å
Authors: Berry S. D. , Lind D. M. , Chern G. , Mathias H. , Testardi L. R.
Published: March 2011

We have investigated the magnetic order, using SQUID magnetometry, for short modulation wavelength Fe3O4/NiO superlattices, grown on single crystal MgO. Ferrimagnetic Fe3O4 has a saturation moment of ~500 emu/cm3 at 0 K and a Curie temperature of 858 K, while bulk NiO is antiferromagnetic with a NMel temperature of 525 K. Very high crystalline quality with little interdiffusion is indicated by X-ray diffraction, SEM, optical microscopy, and in-situ RHEED, and the samples show highly anisotropic electrical conductivity which also indicates the strong modulation present. Long wavelength samples (Amod > 200 Å) have a behavior only slightly different from that expected from bulk Fe3O4, but for Amod<80 Å, spontaneous magnetization is replaced by paramagnetism, with weak temperature dependence (not I/T) from 5 K to 400 K.
Theoretical Studies of Spin Dependent Scatterings of Electrons from Ferromagnetic Surfaces and Ultra Thin Films
Authors: Ormeci A. , Gokhale M. P. , Hall Burl M. , Mills D. L.
Published: March 2011

We summarize results of our recent theoretical studies of spin dependent scattering of electrons from ferromagnetic surfaces. We obtain an excellent account of both the energy and angle variation of the exchange asymmetry reported by Waller and Gradmann in their SPLEED study of the Fe(110) surface, and of spin dependent asymmetries in the transmission of photoelectrons through an ultra thin film of Fe on Cu(100). Potentials supplied by Fu and Freeman enable us to account for the data, with use of ground state potentials generated by ab initio methods.
Investigation of Surface Magnetism by Detection of Polarized Light Emitted After Low Energy He+ Scattering off a Fe(110) Surface
Authors: Schleberger M. , NÄrmann A. , Heiland W. , Huber C. , Kirschner J.
Published: March 2011

We present data from low-energy He+ ion scattering off a magnetized Fe(110) surface where we monitored the circular polarization of the light emitted from particles neutralized into excited states. We investigated the dependence on incident energy, incident angle and magnetization for a singlet and a triplet transition. As expected, there is no dependence on magnetization for the singlet state, but for the triplet transition we observed a difference in the circular polarization of as high as 32% when changing the direction of the magnetization.
Relations of Corrosion Resistance, Coercivity, and Magnetizability of Modified Nd-Fe-B Sintered Magnets to Their Microstructure
Authors: Hirosawa Satoshi , Tokuhara Koki , Mino Shuji , Matsui Toshiyuki , Morii Kenji , Nakayama Yutaka
Published: March 2011

Brief reviews on corrosion and coercivity mechanisms of sintered Nd-Fe-B magnets are given. Results of recently undertaken transmission electron microscopic study of Nd15 - Fe78-xCoxB7 sintered magnets (x = 3, 6 and 10) are presented. Micro-beam electron diffraction patterns obtained from Nd-Co phases in these magnets could be indexed according only to an orthorhombic cell of Nd3 Co among the binary Nd-Co compounds for x = 3 to 10. Relations of coercivity and magnetizability of this type of magnets to their microstructure are discussed in connection to the effects of V or Mo addition which are to enhance coercivity and to improve magnetizability. It is suggested that a decrease in the local demagnetization effects resulting from a decrease in the width of the grain size distribution due to these-additives is the origin of the enhancement of coercivity and the improvement of magnetizability.
Magnetic Order and Structure of Ultrathin Films and Multilayers
Authors: Lugert G. , Bayreuther G. , Lehner S. , Gruber G. , Bruno P.
Published: March 2011

Ultrathin epitaxial films grown in UHV – Fe(110) on Au(111) and Ag(111), Co(0001) on Au(111) – , sputtered Fe films between Ag and sputtered Fe/Au multilayers were studied by SQUID magnetometry and Mössbauer spectroscopy (CEMS). It could be shown that the magnetic anisotropy relative to the film normal, the, ground state magnetic moment per Fe atom and thermal spin excitations are affected by the structure of the films. In particular, a more 3-dimensional growth mode in the early state of film formation which is observed except in a certain temperature range around 300 K reduces the apparent magnetic interface anisotropy and the ferromagnetic ground state moment, and it enhances the thermal spin fluctuations and the tendency for superparamagnetic relaxation in the thinnest films.
Nanoscale Engineered Ceramics From Zeolites: Creating The Ideal Precursor For High-Quality Cordierite
Authors: Bedard Robert L. , Flanigen Edith M.
Published: March 2011

This paper reports the engineering of an ideal zeolite-derived cordierite precursor and addresses the various technological issues that are encountered in the zeolite-to-ceramic process. Mg-exchanged zeolite B (SiO2/Al2O3=2.5) collapses to an amorphous powder at temperatures between 600 and 800°C. The resulting powder can be processed by various standard ceramic methods to give high-quality cordierite parts. The sintering behavior of MgB is described and compared with MgX, another zeolite that is conveniently synthesized with a 2.5 SiO2/Al2O3 ratio. Properties of MgB-derived cordierite are also described.
Low Temperature Studies Of Rare Gases Adsorbed On Molecular Sieve Materials
Authors: Mccann Graham F. , Gameson I. , Steado W.J. , Rayment T. , Barrie P.J. , Klinowski J.
Published: March 2011

X-ray diffraction (XRD) and adsorption isotherms have long been traditional methods of characterising molecular sieves. By combining these techniques at low temperatures with variable temperature 129-Xe N.M.R. we now have a fuller understanding of the behaviour of sorbed layers inside these materials. In particular we have observed phase transformations of Xe in a polyhydroxyaluminium-pillared montmorillonite molecular sieve and have developed a model consistent with the data. In addition, using XRD, an interpillar distance of ca. 30Å was calculated. We present the first detailed low temperature studies of 129-Xe N.M.R. on these systems.
Structural Characterization Of Zeolites Using Raman Scattering
Authors: Deckman H. W. , Creighton J. A. , Buckley R. G. , Newsam J. M.
Published: March 2011

We show that the frequencies of certain optically active lattice vibrational modes in a large number of zeolites can be used as direct structural probes. Mode frequencies are found to depend on the cosine of the T-O-T angle and the Si/Al ratio of the framework. The relationship between mode frequency and local framework structure is discussed in terms of a complete lattice dynamics calculation for specific zeolite structures as well as a lattice dynamical model of amorphous glasses.
Cobalt As A Probe Ion In The Synthesis Of CoAPO-5
Authors: Uytterhoeven M. G. , Keyenberg W. A. Van , Schoonheydt R. A. , Leuven K. U.
Published: March 2011

Diffuse reflectance spectroscopy (DRS) is an excellent technique for the investigation of the synthesis process of CoAPO-5. The DRS intensities increase concomitantly with the crystallinity during synthesis. DRS is also useful in the characterization of the nucleation stage. The transition from an aluminophosphate-hydrate to a non-hydrated structure is observed.
Synthesis And Characterization Of Pillared Acid-Activated Montmorillonites
Authors: Mokaya Robert , Jones William , Whittle Mavis E. , Davies Mary E.
Published: March 2011

Polymeric hydroxy-Al cations were introduced into the interlayer of acid-activated montmorillonites by cation exchange. The resulting pillared materials possessed layer spacings of 18 – 20 Å, surface areas between 250 – 320 m2/g, pore volumes in the range 0.3 – 0.38 cc/g and pore diameters in the range 32 – 40 Å depending on preparation procedures (i.e pillaring temperature and drying method). Powder XRD analysis indicated that the pillars formed were stable to temperatures above 500 °C. The surface acidity of these type of pillared clays was higher than that of pillared non-activated clays. Preliminary studies on their adsorption capacity for chlorophyll showed that they were superior to pillared non-activated clays.
Zirconium Organic Diphosphate-Diphosphonates With Tilted Rigid Pillars.
Authors: Alberti G. , Costantino U. , Vivani R. , Zappelli P.
Published: March 2011

The H2O3PCH(C6H4)2CH2PO3H2 and H2O3PO(C6H4)2OPO3H2 acids were synthesizedT and used to obtain new pillared zirconium phosphonates and organic phosphates in which the pillars are tilted with respect to the layers. The Zr(O3PCH2(C6H4)2CH2PO3) and Zr(O3PO(C6H4)2OPO3) obtained have a good thermal resistance and the distance between the inorganic α-layers joined by the organic pillars is 14.7 and 13.8 Å, respectively. Structural models suggest that the biphenyl groups in the solids are tilted at 140° and 137° with respect to the perpendicular at the layer plane. Solid solutions of the two derivatives over the whole range of composition have also been obtained; the distance between the α-layers changes from 14.7 to 13.8 Å in a continuous way as the diphosphate groups replace the diphosphonate ones, allowing us to suppose a variation of the tilting angles. Attempts to remove the phosphoester in the mixed derivatives by hydrolytic attack, and to replace some pillars with phosphite groups are described.
Formation of A Buried Stacked Insulator by Ion Beam Synthesis
Authors: Skorupa W. , Grotzschel R. , Wollschlagbr K. , Albrbcht J. , Vohse H.
Published: March 2011

We report on the formation and properties of a new type of a buried insulator using combined nitrogen/oxygen implantation with two different implantation energies. In this manner, a stacked layer consisting of silicon dioxide above silicon oxynitride above silicon nitride is formed. Experimental results concerning the impurity profiles, the microstructure and compound formation are presented.
“Equilibrium Oxide” Features of the SIMOX Process
Authors: Hosack H. H. , Hollingsworth J. , El-Ghor M. K. , Joyner K. A.
Published: March 2011

The equilibrium configuration produced when the SIMOX process is carried to the extreme of complete conversion of the silicon film to oxide is described. The thickness of the “equilibrium oxide” produced is modelled using a joined Gaussian approximation to the oxygen implant profile. The “equilibrium oxide” for a 190KeV implant is investigated. This material is found to have a thickness of approximately 5400 angstroms, and to be a very homogeneous film with essentially stoichiometric SiO2 composition. The implications of this work for use of oxides in patterned SIMOX are discussed.
Numerical Simulation of Zone-Melting Recrystallization of Thin Silicon Films With A Tungsten Halogen Lamp
Authors: Robinson Richard D. , Miaoulis Ioannis N.
Published: March 2011

A two dimensional numerical simulation of incandescent lamp Zone-Melting Recrystallization (ZMR) was performed. A parametric study examined the thermal effects of lamp intensity, susceptor temperature, and ambient reflectivity, on the melt zone. The melt zone was found to vary linearly with lamp intensity and parabolically with susceptor temperature and ambient reflectivity.
Oxidation Effects During the Formation of Buried Sb Dopant Profiles in Silicon Using Pulsed Laser Epitaxy
Authors: Carolissen Randall J. , Pretorius R.
Published: March 2011

Severe oxidation inhibited epitaxy when buried Sb profiles in single crystal silicon were formed from evaporated layers irradiated in atmosphere with a pulsed Q-switched ruby laser. Oxygen concentrations as high as 5×1017atoms/cm2 (equivalent to 105nm SiO2) were measured. However, structures prepared without the Sb layer and irradiated under identical conditions, showed no oxidation. Oxidation of Sb as a source of the measured oxygen was ruled out, while the total heating time during laser irradiation is so short (nano- to milliseconds) that normal oxidation kinetics cannot account for the amount of SiO2 measured. Irradiations in vacuum and in a helium ambient showed that the oxygen responsible for these effects is supplied from the ambient in which irradiations are carried out. Also no oxidation was observed when structures, prepared on a substrate heated to 350°C, were irradiated in atmosphere. A model to account for these oxidation effects is proposed.
Localized States in Electron-Irradiated GaAs
Authors: Kouimtzi S. D. , Melidis C. , Achtlleos C.
Published: March 2011

Band tailing produced by electron irradiation of n-type GaAs at helium temperatures is studied. It has been observed that conductance in the band tailing occurs via localized states as evidenced by the observation of a conductance having a frequency dependence of the form σ⊥ωs where ≈ 1.

Sufficient degree of damage induces variable range hopping, σ ∝ exp (-b/Tl/4) in a defect band. The frequency dependence of the conductivity in this band is very weak.
Dependence of Buried CoSi2 Resistivity on ION Implantation and Annealing Conditions1
Authors: Namavar Fereydoon , Kalkhoran N. M. , Manke J. M. , Luo L. , McGinn J. T.
Published: March 2011

We have investigated the dependence of electrical and material properties of buried CoSi2 layers on Co+ implantation and annealing conditions. The results indicated that the electrical resistivity and crystalline quality of the implanted buried CoSi2 layers depend strongly on the implantation temperature. CoSi2 layers with the lowest resistivity and best crystalline quality (Xmin as low as 3.6%) were obtained from samples implanted at 300°C-400°C. Implantation at higher temperatures (e.g., 580°C) produced cobalt disilicide layers with significantly higher electrical resistivity and a Xmin of about 10.7%.
Temperature Effects in Ion Beam Mixing of Oxide-Oxide Interfaces
Authors: Joslin D. L. , Romana L. J. , White C. W. , McHargue C. J. , Thévenard P. A. , Honon L. L.
Published: March 2011

Ion beam mixing of thin oxide films, Cr2O3 and ZiO2, on sapphire substrates has been studied. The systems were chosen according to their solubilities in α-Al2O3: Cr2O3 is completely soluble, while ZrO2 is insoluble. Mixing experiments were performed on 50 nm-thick Cr2O3 and ZrO2 films deposited on αAl2O3 by radio frequency (rf) sputter deposition. The specimens were bombarded with Cr+ at an energy of 160 keV to a fluence of 4×1016 ions-cm−2. Implantations were performed at 25 and 860°C. Rutherford backscattering spectroscopy was performed to analyze any interface modifications due to the bombardment. No detectable mixing was observed in either system for irradiations performed at 25°C, but a small amount of ballistic mixing was observed in both systems at 860°C.
Optical and Infrared Spectroscopy of Laser Irradiated BI Implanted SiO2 Glasses
Authors: Magruder R. H. , Henderson D. O. , Morgan S. H. , Zuhr R. A.
Published: March 2011

Optical and infrared reflection spectra for Bi-implanted high-purity silica are reported as a function of dose and 5eV laser irradiation. The extinction coefficient per ion and the reflectance spectra are dose dependent. Subsequent effects of laser irradiation are dependent upon Bi content and total number of laser pulses. Changes reported are attributed to two photothermal processes. One involving diffusion and desorption of Bi ions and annealing of defects, while the second is dominated by annealing.
Collisional Energy Deposition Threshold for Extended Damage Depths in Ion-Implanted Silicates
Authors: Arnold G. W. , Battaglin G. , Boscolo-Boscoletto A. , Caccavalle F. , De Marchi G. , Mazzoldi P.
Published: March 2011

Many properties of implanted fused silica (e.g., surface stress, hardness) exhibit maximum implantation-induced changes for collisional energy deposition values of ∼1020 keV/cm3. We have observed a second critical energy deposition threshold value of about 1022 keV/cm3 in stress and hardness measurements as well as in many other experiments on silicate glasses (leaching, alkali depletion, etching rate, gaseous implant redistribution). The latter show evidence for damage depths exceeding TRIM ranges by about a factor of 2. For crystalline quartz, a similar threshold value value has been found for extended damage depths (greater than TRIM) for 250 kev ions (H-Au) as measured by RBS and interference fringes. This phenomenon at high damage deposition energy may involve the large stress gradients between damaged and undamaged regions and the much increased diffusion coefficient for defect transport.
Plastic Deformation and Micro-Fracture in SiO2 Induced by Electron Beam Irradiation
Authors: Ajayan P. M. , Iijima Sumio
Published: March 2011

We present here experimental results using transmission electron microscopy (TEM) and real time video recordings, of the many dynamic structural instabilities in amorphous silica structures during intense electron beam irradiation. It is observed that while the silica layers on oxidized silicon particles sinter when irradiated uniformly, they undergo necking and extensive plastic deformation when the beam is focused in the neck regions. Extremely thin silica fibers (less than five nanometers in diameter and microns in length) can be produced by the deformation of such necks between particles. The thin fibers and the sharp tips developed from the failure of such structures are seen to spheroidize and blunt when exposed to the electron beam. The instabilities are thought to arise from irradiation induced charging of the insulator surface which expands to reduce the density of accumulated surface charges.
Pulsed Laser Annealing of Buried Damage in Ion Implanted Diamond
Authors: Prawer Steven , Jamieson D. N. , Dooley S. P. , Spizzirri P. , Ghiggino K. P. , Kalish R.
Published: March 2011

Damaged layers, buried underneath the surface of type IIa diamond slabs by 2.8 MeV C+ ion implantation have been subjected to irradiation with 14 ns pulses from a focused Nd-Glass laser. At high powers, ablation of the implanted surface was observed. However, the correct choice of laser power and wavelength results in annealing of the implanted layer without any disruption to the surface morphology. Annealing was confirmed by optical measurements showing a decrease in the GR-1 absorption band, and by channelled Rutherford Backscattering Spectroscopy on the small 10μm diameter laser irradiated spots. The results suggest that an undamaged diamond cap can be utilized to promote damage annealing of diamond by pulsed laser beams, for which the annealing in other materials has been shown to proceed via the melt. The surface cap is believed to aid in the production of extremely high internal pressures in the damaged layer during the laser pulse which prevents graphitization and promotes diamond regrowth.
Hardening in AlN Induced by Point Defects
Authors: Suematsu H. , Mitchell T. E. , Iseki T. , Yano T.
Published: March 2011

Pressureless-sintered AlN was neutron irradiated and the hardness change was examined by Vickers indentation. The hardness was increased by irradiation. When the samples were annealed at high temperature, the hardness gradually decreased. Length was also found to increase and to change in the same way as the hardness. A considerable density of dislocation loops still remained, even after the hardness completely recovered to the value of the unirradiated sample. Thus, it is concluded that the hardening in AlN is caused by isolated point defects and small clusters of point defects, rather than by dislocation loops.

Hardness was found to increase in proportion to the length change. If the length change is assumed to be proportional to the point defect density, then the curve could be fitted qualitatively to that predicted by models of solution hardening in metals. Furthermore, the curves for three samples irradiated at different temperatures and fluences are identical. There should be different kinds of defect clusters in samples irradiated at different conditions, e.g, the fraction of single point defects is the highest in the sample irradiated at the lowest temperature. Thus, hardening is insensitive to the kind of defects remaining in the sample and is influenced only by those which contribute to length change.
Phase Transformations by Yttrium Implantation into Pure Aluminum
Authors: Ning X. G. , Ji C. Z. , Ye H. Q.
Published: March 2011

Phase transformations by yttrium implantation into pure aluminum using 60kV ions and 3×1017 ions/cm2 dose have been studied by transmission electron microscopy (TEM). YAl3(12R) particles with an average size of 0.3μm were formed in the modified aluminum surface, which transformed into YFe3·5Alx (predominantly) and YAl3(8H) phase particles with 2 μm average diameter after being annealed at 600°C for one hour. The Fe ions were introduced by ion sputtering from the iron screws of the specimen holder, a previously unnoticed effect during heavy metal ion implantation for surface modification of materials. Electron diffraction experiments indicated that the YFe3·5Alx was a new phase and belongs to the orthorhombic system with a C-face-centered lattice (a=c=0.887nm, b=1.024nm). The reciprocal lattice of the YFe3·5Alx phase is related to that of the YFe4Al8 magnetic phase. The microstructure of the modified aluminum surface was also investigated by high-resolution TEM.
RBS/Channeling Diffusion Studies of High Energy Au Implanted Mg Single Crystals
Authors: Da Selva R. C. , Da Silva M. F. , Thomé L. , Melo A. A. , Soares J. C.
Published: March 2011

RBS/channeling analyses of high energy Au implantation into Mg are presented. The diffusion behaviour of Au was studied and the occurrence of essentially two distinct regimes were observed: the segregation regime at lower temperatures correlated with the damage introduced by the high energy implantation and the higher temperature regime as a normal thermally activated process of back-diffusion.
Analysis of Experiments in Helium Microbeam Mixing
Authors: Davis John B. , Benenson R. E. , Peak David
Published: March 2011

We have continued to investigate ion-beam mixing in bilay-er targets irradiated by 2-MeV He+ microbeams at room temperature. Although we have previously reported a linear dependence of interface width on dose for Cu/Al targets 1, more extensive results have not supported this conclusion, within statistical uncertainty, it appears that the interface width in Cu/Al (1) is proportional to the square root of dose, at constant dose rate, (2) is larger in Al than in Cu, for the same dose, (3) is proportional to the 1/4 power of dose rate, and (4) is absent at liquid nitrogen temperature. Calculations of the expected interface growth rate from a radiation-enhanced diffusion model have provided order-of-magnitude agreement with observed rates. Additionally, intermixing of Cu and Al outside the damaged area may indicate significant transverse diffusion of vacancies.
Radiation Enhanced Tracer Diffusion in Intermetallic Alloys
Authors: Lee Y. S. , Averback R. S. , Flynn C. P.
Published: March 2011

Radiation enhanced diffusion in the intermetallic alloy Cu3Au was measured directly for the first time. Ni and Pd tracer impurities were used to probe the diffusion of atoms occupying Cu and Au sublattice site's, respectively. Measurements were performed temperatures both above and below the ordering temperature, of TC =390°C The ability to grow high quality Cu3Au films by MBE with buried marker layers in the form of either (Cu2Ni)Au or Cu3(AuPd), made these measurements possible. Under irradiation with 0.75MeV Ar+ ions, the diffusion of Ni is approximately equal to that of Pd above Tc, but smaller below Tc. In the absence of irradiation, the thermal diffusion coefficients reveal a similar trend. Activation energies for RED for the two species are similar both above and below Tc whereas, in absence of irradiation, the activation enthalpies below Tc are different. These results are interpreted on the basis of lattice order.
The Effect of Ion Irradiation on Inert Gas Bubble Mobility
Authors: Alexander Dale E. , Birtcher R. C.
Published: March 2011

The effect of Al ion irradiation on the mobility of Xe gas bubbles in Al thin films was investigated. Transmission electron microscopy was used to determine bubble diffusivities in films irradiated and/or annealed at 673K, 723K and 773K. Irradiation increased bubble diffusivity by a factor of 2–9 over that due to thermal annealing alone. The Arrehnius behavior and dose rate dependence of bubble diffusivity are consistent with a radiation enhanced diffusion phenomenon affecting a volume diffusion mechanism of bubble transport.
Structure Transformations of the Decagonal and Icosahedral Phases in Quaternary Alloys.
Authors: Perez R. , Reyes-Gasga J. , Jose-Yacaman M.
Published: March 2011

An investigation of the phase transformations experienced by the decagonal and icosahedral phases in two different quaternary -alloys is carried out. The transformation in the decagonal phase of Al-Cu-Co-Si alloy is induced by the electron radiation in a transmission electron microscope. However, in the icosahedral phase of Al-Cu-Co-Fe alloy this transformation is induced by annealing. Electron diffraction patterns obtained from both phases suggest that the deformation mechanism involved in these kind of transitions is related with twinning
Interdiffusion and Grain-Boundary Migration in Au/Cu Bilayers During Ion-Irradiation
Authors: Alexander Dale E. , Rehn L. E. , Baldo Peter M.
Published: March 2011

Ion irradiation and annealing experiments have been conducted on Au/Cu bilayer films to evaluate the effect of irradiation on diffusion-induced grain boundary migration (DIGM). The Au films were prepared with a large-grained microstructure with grain boundaries perpendicular to the film surface and extending through the film thickness. Irradiations were conducted with 1.5 MeV Kr at 228°C. Rutherford backscattering spectrometry of the samples revealed that interdiffusion was substantially enhanced in the irradiated area relative to the unirradiated area. Both irradiated and annealed-only areas were characterized by a nearly uniform composition of 14 at.% and 7 at.% Cu respectively through the entire thickness of the underlying Au film. Small probe X-ray energy dispersive spectroscopy showed significant lateral compositional homogeneities in both irradiated and annealed areas. These two results are consistent with previous observations of DIGM in the Au/Cu system, suggesting that this previously unexamined interdiffusion mechanism contributes to ion beam mixing.
Ion Induced Grain Growth in Pd
Authors: Lilienfeld D. A. , Bøorgesen P. , Meyer P.
Published: March 2011

Ion irradiation induced grain growth size distributions in Pd are examined at low temperatures. Two features are observed: 1) A majority of the grains saturate in size. 2) Some grains achieve sizes much larger than the average grain size and continue to grow with ion dose. However, by careful choice of ion mass and ion dose, it is possible to produce a sample possessing a monomodal grain size. This process will have applications in producing thin films of nanocrystalline materials.
Stress and Phase Changes in Ion-Assisted Evaporation of Thin Tantalum Films
Authors: Roy R. A. , Catania Philip
Published: March 2011

Ion-assisted evaporation was used to study the stress and phase changes in thin Ta films. Using a series of ion energies from 63 to 500 eV, the stress in 100 nm thick films was changed from tensile to compressive by increasing the argon ion flux incident on the growing films. The resulting films were characterized primarily by x-ray diffraction and electrical resistivity measurements, as well as RBS. The resistivity in all sets of films shows a large decrease with increasing argon ion flux. The x-ray diffraction results are somewhat more complex, but suggest that increasing ion flux does change the amount of alpha phase present.
Epitaxy and Chemical Reactions During Thin Film Formation from Low Energy Ions New Kinetic Pathways, New Phases and New Properties
Authors: Herbots Nicole , Hellman O. C. , Vancauwenberghe O.
Published: March 2011

Three important effects of low energy direct Ion Beam Deposition (IBD) are the athermal incorporation of material into a substrate, the enhancement of atomic mobility in the subsurface, and the modification of growth kinetics it creates. All lead to a significant lowering of the temperature necessary to induce epitaxial growth and chemical reactions. The fundamental understanding and new applications of low temperature kinetics induced by low energy ions in thin film growth and surface processing of semiconductors are reviewed. It is shown that the mechanism of IBD growth can be understood and computed quantitatively using a simple model including ion induced defect generation and sputtering, elastic recombination, thermal diffusion, chemical reactivity, and desorption. The energy, temperature and dose dependence of growth rate, epitaxy, and chemical reaction during IBD is found to be controlled by the net recombination rate of interstitials at the surface in the case of epitaxy and unreacted films, and by the balance between ion beam decomposition and phase formation induced by ion beam generated defects in the case of compound thin films. Recent systematic experiments on the formation of oxides and nitrides on Si, Ge/Si(100), heteroepitaxial SixGe1−x/Si(100) and GaAs(lOO) illustrate applications of this mechanism using IBD in the form of Ion Beam Nitridation (IBN), Ion Beam Oxidation (IBO) and Combined Ion and Molecular beam Deposition (CIMD). It is shown that these techniques enable (1) the formation of conventional phases in conditions never used before, (2) the control and creation of properties via new degrees of freedom such as ion energy and lowered substrate temperatures, and (3) the formation of new metastable heterostructures that cannot be grown by pure thermal means.
Low Temperature Silicon Epitaxial Growth by Plasma Enhanced Chemical Vapor Deposition From SiH4/He/H2
Authors: Lin Yung-Jen , Shieh Ming-Deng , Lee Chiapying , Yew Tri-Rung
Published: March 2011

Silicon epitaxial growth on silicon wafers were investigated by using plasma enhanced chemical vapor deposition from SiH4/He/H2. The epitaxial layers were growm at temperatures of 350°C or lower. The base pressure of the chamber was greater than 2 × 10−5 Torr. Prior to epitaxial growth, the wafer was in-situ cleaned by H2 baking for 30 min. The epi/substrate interface and epitaxial layers were observed by cross-sectional transmission electron microscopy (XTEM). Finally, the influence of the ex-situ and in-situ cleaning processes on the qualities of the interface and epitaxial layers was discussed in detail.
Growth And High Resolution Tem Characterization of GexSi1−x/Si Hetero-Structures by Remote Plasma-Enhanced Chemical Vapor Deposition
Authors: Qian R. , Chung I. , Kinosky D. , Hsu T. , Irby J. , Mahajan A. , Thomas S. , Banerjee S. , Tasch A.
Published: March 2011

Remote Plasma-enhanced Chemical Vapor Deposition (RPCVD) has been used to grow GexSi1−x/Si heteroepitaxial thin films at low temperatures (∼450°C). In situ RHEED has been used to confirm that smooth, single crystal heteroepitaxial films can be grown by RPCVD. Plan-view and cross-sectional TEM have been employed to study the microstructure of the heteroepitaxial films. Lattice imaging high resolution TEM (HRTEM) has shown perfect epitaxial lattice alignment at the heterojunction interfaces. GexSi1−x/Si films which exceed their CLT's appreciably show dense Moiré fringes under plan-view TEM. The spacings between the fringes have been used to estimate the relaxed lattice constants. In addition to the inhomogeneous strain observed in-XTEM, Selected Area electron Diffraction (SAD) analysis of the interfaces displays two split patterns. The spacings between the diffraction spots have been used to calculate the lattice constants in the epitaxial films in different crystal directions, which agree very well with the prediction by Vegard's law as well as the estimate from plan-view TEM analysis. HRTEM analysis also reveals the crystallographic nature of the interfacial misfit dislocations in the relaxed films.
Growth Mechanism and Film Properties in Pulsed Laser-Plasma Deposition
Authors: Metev S. , Meteva K.
Published: March 2011

In the paper the results of a theoretical investigation of the growth process of laser-plasma deposited thin films are discussed. A kinetic approach has been used to establish direct relation between experimental conditions (laser flux density, substrate temperature) and film properties (thickness, structure). The results of some experimental investigations of the deposition process are presented confirming the general conclusions of the developed theoretical model.
Synthesis and Characterization of PbO Films Grown by Pulsed Laser Deposition.
Authors: Zabinski J. S. , Donley M. S. , Dyhouse V. J. , Moore R. , McDevitt N. T.
Published: March 2011

Lead monoxide (PbO) is a potential solid lubricant for use at elevated temperatures in oxidizing environments. The objective of this research was to grow thin films of PbO by Pulsed Laser Deposition (PLD). Film stoichiometry, crystallinity, and chemistry were adjusted by varying substrate temperature and O2 partial pressure during deposition and the effects of changes in film properties on friction coefficients and wear lives were investigated. Chemistry and crystallinity were evaluated using X-ray photoelectron spectroscopy (XPS), Raman spectroscopy, and glancing angle X-ray diffraction (XRD). Friction coefficients and wear lives were measured in dry nitrogen and at room temperature using a ball-on-flat tribometer. Films deposited at room temperature retained the crystal structure of the target material, but were oxygen deficient. The O/Pb ratio was increased by raising the O2 partial pressure and by increasing the substrate temperature during deposition; the crystal structure and orientation changed with stoichiometry. Friction coefficients ranged from 0.20 – 0.45 and the wear lives were typically less than those obtained from MoS2 films.
Low Temperature Synthesis of Carbide Thin Films by Pulsed Laser Deposition (PLD)
Authors: Donley M. S. , Zabinski J. S. , Sessler W. J. , Dyhouse V. J. , Walck S. D. , McDevitt N. T.
Published: March 2011

Thin films of titanium carbide (TiC) and boron carbide (B4C) were grown by excimer pulsed laser deposition (PLD) at room temperature (RT) and 300°C. Films were deposited using the output of an excimer laser operating with KrF gas (γ = 248 nm, 15 ns pulse duration) to ablate hot-pressed targets. Film chemistry, morphology, and crystallinity were investigated. Stoichiometric, crystalline TiC films were grown on 440C stainless steel and NaCl substrates at room temperature and at 300°C. The films grown on NaCl were nanocrystalline, cubic TiC, with a grain size ranging between 2 and 10 nm in diameter. Boron carbide films were grown on silicon {100} substrates at room temperature and at 300°C. Film chemistry and stoichiometry duplicated that of the B4C target, which contained B4C and a mixed C-B-O-N binder phase. SEM analysis indicated that the morphology of the films was uniform, non-porous, and fine-grained. The films exhibited good adhesion and wear resistance, based on friction and wear data collected with a ball-on-disc tribometer.
Comparison in Surface Modifications of Sintered and Single Crystal Ceramic Targets After Laser Ablation
Authors: Young K. H.
Published: March 2011

A systematic study of the surface morphology and chemical composition of several ceramic targets after pulsed laser ablation has been conducted using a scanning electron microscope with x-ray energy dispersive spectroscopy. We have examined single crystal LaAlO3 and NdGaO3 disks, as well as powder sintered LaAlO3 and SrTiO3 discs. These targets were rotated during laser ablation and concentric trenches were formed with distinctive surface morphologies due to different doses of laser energy. We observed varied light-solid surface interactions on the targets prepared by different methods. The sintered targets exhibited surface explosions after long period laser ablation, presumably due to sub-surface overheating [1]. The single crystal targets have smoother surface morphology and the resulting films have much fewer particles on the surface. As such, they are preferred for laser ablation applications.
Heat Transfer in Laser Annealing of Semiconductor Films
Authors: CriGoropoulos C. P. , Xu X. , Taylor S. L. , Park H. K.
Published: March 2011

Melting and solidification of a silicon film by continuous wave laser beam irradiation has been studied. The silicon film melting and recrystallization is controlled by the temperature distribution in the semiconductor. Calculations have been carried out for a range of laser beam parameters and material translational speeds. The results for the melt pool size have been compared with experimental data. The temperature field development has also been monitored with localized transient reflectivity measurements.
Selective-Area Growth of Metal Oxide Films Induced by Patterned Excimer Laser Surface Photolysis
Authors: Kunz R. R. , Ehrlich D. J. , Melngailis J. , Horn M. W.
Published: March 2011

An excimer-laser-based method for achieving selective-area oxide growth on polymer surfaces is described. This method uses high photon energy (6.4 eV, 7.9 eV) excimer laser irradiation to change hydrophobic surfaces (surface tension <20 erg/cm2) into hydrophilic surfaces. The hydrophobic growth surfaces are prepared by exposure of a polymer to halogen-containing plasmas. Selective growth is done by simultaneously exposing patterned, laser-modified surfaces to SiC14 and H2O; the reaction takes place only where the H2O adsorbs to form a condensed adlayer. After selective growth, oxygen etching of the polymer results in the desired resist pattern. When used with a plasma-deposited carbon polymer, the result is a new all-dry lithographic process.