bluuebunny/crossref_metadata_2025_split huggingface dataset:
The Roles of Energetic Displacement Cascades in Ion Beam Modifications of Materials
Authors: Averback R. S. , Kim S. -J. , Rubia T. Diaz de la 
Published: March 2011

AbstractThe roles of energetic displacement cascades are ubiquitous in the fields of radiation damage and ion beam modifications of materials. These roles can be described on two time scales. For the first, which lasts ≈ 10-11 s, small cascade volumes are characterized by large supersaturations of point defects, structural disorder, and energy densities in excess of some tenths of eV's per atom. During this period, the system can be driven far from equilibrium with significant rearrangement of target atoms and the production of Frenkel pairs. Experimental studies of ion beam mixing in conjunction with molecular dynamics computer simulations, have contributed largely toward understanding these dynamic cascade processes. At later times, the microstructure of the material evolves as cascades begin to overlap, or at elevated temperatures, point defects migrate away from their nascent cascades. It will be shown how the primary state of damage in cascades influences this microstructural development. Examples involving radiation-enhanced diffusion and ion-induced amorphization will be discussed.
Investigations of Low-Temperature Epitaxy, Ion Damage, and Reactive-Ion Cleaning Utilizing Ion Beam Deposition
Authors: Appleton B. R. , Zuhr R. A. , Noggle T. S. , Herbots N. , Pennycook S. J. 
Published: March 2011

AbstractThe technique of ion beam deposition (IBD) is utilized to investigate low-energy, ion-induced damage on Si and Ge; to study reactive ion cleaning of Si and Ge; to fabricate amorphous isotopic heterostructures; and to fabricate and study the low-temperature epitaxial deposition of 74Ge on Ge(100), 30Si on Si(100), and 74Ge on Si(100). The techniques of ion scattering/channeling and cross-sectional TEM are combined to characterize the deposits.
Mesotaxy: Formation of Buried Single-Crystal CoSi2 Layers by Implantation
Authors: White Alice E. , Short K. T. , Dynes R. C. , Garno J. P. , Gibson J. M. 
Published: March 2011

AbstractUsing high dose implantation of 200 keV Co ions followed by high temperature annealing, we have created buried layers of CoSi2 in crystalline Si of both (100) and (111) orientations. For a dose of 3 × 1017 Co/cm2, the layer that forms is ∼1100Å thick and the overlying Si is ∼600Å thick. A lower dose of 2 × 1017 Co/cm2 yields a thinner layer, 700Å thick, under 1200Å of crystalline Si. Rutherford Backscattering and channeling analysis of the layers shows that they are aligned with the substrate (χmin of the Co as low as 6.4%.) and TEM inspection of the (100) CoSi2/Si interfaces shows that they are abrupt and epitaxial (with occasional small facets). Moreover, electrical characterization of these layers yields resistance ratios that are better than epitaxial CoSi2 films grown by more conventional UHV methods.
Systematics of Silicide Formation by High Dose Miplantation of Transition Metals into Si
Authors: Namavar F. , Sanchez F. H. , Budnick J. I. , Fasihuddin A. H. , Hayden H. C. 
Published: March 2011

AbstractWe have systematically studied the formation of transition-metal thin films by high dose (up to 1018 ions/cm2) implantation of Ti, V, Cr, Mn, Fe, Co, Ni and Nb at room temperature and 350°C into Si <100>.For implantation at 350°C, our results, as obtained by Rutherford backscattering, X-ray diffractometry and Read Camera measurements, indicate that one can categorize these metals into two groups:
1.a chromium group which includes V, Cr, Nb, Ti and Mn. Metals V, Cr and Nb form compounds (VSi2, CrSi2. NbSi2) with a hexagonal structure of the CrSi2 type whereas Ti and Mn both form compounds (Ti5Si3, Mn5Si3) with a hexagonal structure of the Mn5Si2 type.2.an iron group which includes Fe, Co and Ni. These metals form compounds (FeSi, CoSi, NiSi) with a cubic structure of the FeSi type.In this paper the experimental results for Cr and Fe implantation at room temperature and 350°C will be discussed.
Ion-Induced Growth of Whiskers on Sn Films
Authors: Poker D. B. , Schubert J. , Stritzker B. 
Published: March 2011

AbstractWhiskers have been observed to form on thin films (1000–2000 Å) of Sn following implantation of 20-keV H or He at temperatures below 150 K. The morphology of the whiskers following growth was examined using scanning electron microscopy (SEM) to illuminate the possible growth modes. In an effort to obtain support for either of several models of the growth process, the region near the base of the whiskers was examined for evidence of depletion or extrusion. No evidence of depletion was observed. The whiskers could be classified into two types: those that were supported on pedestals, a short transition region at the base of the whisker; and those without pedestals, which rose abruptly from the film with no transition. A novel structure has been observed on Sn films that were coated with 500 Å of Au/Pd to enhance the SEM image. The structure consists of a thin, planar surface several microns in length, oriented perpendicular to the substrate. The structures did not appear immediately after coating, but were present after storage in air for one month.
Growth Mechanisms During Thin Film Crystallization From the Melt
Authors: Pfeiffer Loren , Gelman A. E , Jackson K. A. , West K. W 
Published: March 2011

AbstractWe develop a model that appears to account for the existence of a new mode of crystallization recently discovered during zone-melt-recrystallization (ZMR) of silicon thin films on SiO 2 using a scanned strip heater or lamp. Transition to the new crystallization regime is induced by reducing the temperature of the scanned upper heater strip, thus reducing dT/dy, the thermal gradient along the direction of scan at the silicon solidification front. If dT/dy ≤:4 K/mm, the single crystal films have long non-branched subboundaries with tilt misalignments of 0.1 or less, a lateral separation in excess of 50 µm, and consist of rows of short dislocations threading through the film thickness and terminating at the two SiO2 layers. This is in marked contrast to material ZMR scanned at higher dT/dy which shows conventionally branched 1 to 3 subboundaries that consist of edge dislocations running in the plane of the film often for several hundred microns.Our model extends the {111} faceted-freezing-front picture we have developed previously to take into account the freezing profile with respect to film thickness, and in particular to such profiles at the intersections of pairs of {111} facets where subboundaries are known to form. We propose that the melt-freezing interface profiles at these interior corner intersections are aligned approximately normal to the scan in the high gradient case, but become tilted towards the plane of the SiO2 cap layer for the low gradient case. This tilting accounts in a natural way for the transition from in-plane to threading dislocations.
Solidification Interface Morphologies in Zone Melting Recrystallization
Authors: Im J. S. , Thompson C. V. , Tomita H. 
Published: March 2011

AbstractUsing in situ optical microscopy we have studied the morphology of the liquid-solid interface during zone melting recrystallization. We have observed a variety of interface morphologies, each of which corresponds to specific types and distributions of subboundaries in the solidified material. We have also observed a variety of morphologies for stationary interfaces. We propose that perturbations in both the stationary and moving liquid-solid interfaces develop, at least in part, due to the spatial gradient in the radiation intensity in the region of the interface.
Origin of Subboundary Formation in Encapsulated Recrystallized Si Films on SiO2
Authors: Kamgar Avid , Nakahara S. , Knoell R. V. 
Published: March 2011

AbstractWe have made extensive microdiffraction studies of the crystallographic orientation of recrystallized (001) Si films, and transmission electron microscopy (TEM) analysis of dislocations at the initiation sites of the subboundaries. The microdiffraction studies reveal a characteristic folding behavior between the subgrains with an increasing tilt angle in the direction away from the initiation sites. The TEM results show straight dislocations along the [110] direction initiating from the nucleation site, the appearance of curved dislocations, and buckling of the epi film around the nucleation site, all indicative of a strong bending force at the initiation site. These two predominant characterististics of the recrystallized films, i.e., (1) crystallographic orientation of the subgrains, and (2) subboundaries together with their associated defects can be successfully interpreted in terms of the model which we recently proposed for the subboundary formation.
The Role of Implant Temperature in the Formation of Thin Buried Oxide Layers
Authors: White Alice E. , Short K. T. , Pfeiffer L. N. , West K. W. , Batstone J. L. 
Published: March 2011

AbstractFrom the early work on high dose oxygen implantation for buried SiO2 formation, it is apparent that the temperature of the Si substrate during the implant has a strong influence on the quality of both the SiO2 layer and the overlying Si. This, in turn, can be related to the damage from the oxygen implant. For substrate temperatures < ∼ 300°C, amorphous Si is created during the implant and leads to the formation of twins or polycrystalline Si during the subsequent high temperature (>1300°C) anneal. At higher substrate temperatures (<∼400°C), dynamic annealing eliminates the amorphous Si, but the implanted oxygen appears to segregate during the implant leading to oxygen-rich amorphous regions imbedded in regions of crystalline material. As the amorphous regions start to coalesce and form SiO2 during the high temperature anneal, they trap crystalline Si which cannot escape by diffusion. This process can be circumvented by using a randomizing Si implant to change the damage structure from the oxygen implant before annealing. We have seen these effects clearly in sub-stoichiometric implants, and believe they are also operative during stoichiometric implants.
Characterization and Evolution of Microstructures Formed by High Dose Oxygen Implantation of silicont
Authors: El-Ghor M. K. , Pennycook S. J. , Sjoreen T. P. , Narayan J. 
Published: March 2011

AbstractHigh doses of oxygen were implanted in silicon to produce stoichiometric buried oxide structures. Microstructural analysis was performed using transmission electron microscopy, electron energy loss spectroscopy, and Rutherford backscattering/channeling techniques. Cavities were observed in the top silicon layers of the as-implanted samples in two forms: spherical cavities (30–300 Å in diameter) in the first 1000 Å below the surface, followed by a 500 Å wide lamellar array of elongated cavities. A post implantation annealing was carried out at temperatures between 1150°C and 1250°C for 3 h during which the cavities became faceted and a denuded zone of 400 Å was formed. However, with a 1300°C anneal the cavities disappeared and the density of the two prominent types of defects, namely precipitates (mostly amorphous, but occasionally crystalline) and dislocations, decreased significantly. The silicon-oxide interface became increasingly planar. Possible mechanisms of annealing of the cavities, the precipitates, and the associated planarization of the interface are proposed.
A Study of the Effects of Implantation Dose and Annealing Temperature on the Formation of Buried Nitride SOI Structures
Authors: Kerger M. B. , Kwor R. , Zeller M. , Hemment P. L. F. , Reeson K. J. 
Published: March 2011

AbstractNitrogen implantation into single-crystal silicon can result in a buried nitride layer under proper processing conditions. SOI structures have been formed using this technique. The optimum parameters for forming a buried nitride layer with good insulating characteristics have been investigated. Nitrogen was implanted into <100> silicon at 200 keV at an implantatipp tem erature of 500°C. The effect of implantation doses of 1.05 × 1018N+/cm2, 1.3 × 1018N+/cm+ and 1.4 × 1018N+ /cm+ and post-implantation annealing temperatures of 1050, 1100, 1150, and 1200°C on the buried nitride layer was studied. Transmission Infrared Spectroscopy was used to determine the structure (amorphous or crystalline) of the buried nitride layer. The infrared spectra change as a function of annealing temperature, indicating the transition from amorphous to crystalline silicon nitride. Leakage currents through the structures were measured and SEM micrographs of the nitride surfaces were taken. The correlation between the IR results and these data will be presented.
Rapid Thermal Annealing of Ni/Al/Si and Ni/Si Systems
Authors: Katz A. , KOMEM Y. 
Published: March 2011

AbstractThe effect of Rapid Thermal Annealing on phase formation and diffusion processes in the Ni(30 nm) /Al(10 nm)/Si system was studied and coxpared to a Ni(30 nm)/Si reference system. Heat treatments were carried out at temperatures between 400°C and 900°C for 2 seconds.The results obtained by means of TEM, AES and XRD indicated that the Ni/Al/Si system underwent a local melting in the intermediate Al layer at the Al/Si eutectic temperature (577°C). This reaction, due to the rapid melting process, resulted in formation of a unique layered-structure composed of a columnar polycrystalline layer (60 nm thick) of Ni2Si and NiSi adjacent to the Si substrate with relatively smooth interface and an outer layer of two separate polycrystalline films (both about 10 m thick) of Al3Ni (inside) and Ni(Al0.5Si0.5 ) (outside). Under the same rapid thermal processing conditions the Ni/Si reference system underwent a solid state reaction which resulted in the formation of a polycrystalline layer (60 nm thick) composed of Ni2Si and NiSi as well as NiSi2.
The Effects of Processing Ambient on the Reaction Rate of Ti and Si Using Rapid Thermal Processing
Authors: Kermani A. , Farnam K. , Stultz T. 
Published: March 2011

AbstractThe reaction rate of sputter deposited Ti films on c-Si as a function of process ambient was studied. Sintering temperatures ranging from 600 to 1100° C, under pure ammonia, forming gas, nitrogen and argon were used. The additional effect of a reactively sputtered TiN cap on the reaction rate was also investigated. Processed films were then analyzed using AES, RBS and four point probe resistivity mapping. It was found that for temperatures below 700° C, an ammonia ambient has the most pronounced effect on reducing the rate of formation of titanium silicide, followed by forming gas (N 2/H2 10% vol), nitrogen and argon. Additionally, the presence of the TiN cap further reduced the reaction rate while exhibiting significant diffusion of nitrogen into the silicide film. For the samples annealed in ambients containing nitrogen, a thin layer of Tix Ny was simultaneously formed on top of the silicide film. The thickness and Stoichiometry of this titanium nitride films were then correlated with the sintering temperature and ambient. The details of these findings and their impact on the formation of the self-aligned titanium silicide (salicide) will be presented.
Uniform Tetragonal WSi2 Layers Formed by RTA
Authors: Siegal M. , Santiago J. J. , Spiegel J. Van Der , Graham W. R. , Setton M. 
Published: March 2011

AbstractThin films of tungsten silicide with resistivities of 30 – 35 μΩ-cm have been formed by sputter depositing 71 nm of W metal onto (100) oriented, 5 Ω-cm, p-type silicon wafers that were etched in BOE 500 solution. The samples were fast radiatively processed in an RTA system under high vacuum for time anneals ranging from 15 – 50 seconds at a temperature of ∼ 1100°C. The inevitable oxide barrier at the interface is shown to decrease with increasing RTA time.
Effectiveness of Thin Film Encapsulants for Reducing Evaporation during Rapid Thermal Processing of GaAs
Authors: Haynes T. E. , Picraux S. T. , Chu W. K. 
Published: March 2011

AbstractA technique is described for direct measurement of evaporation of Ga and As from capped GaAs during RTP. Application of this method to the study of Si, SiO2, and Si3N4 caps with thicknesses of 20 nm to 60 nm provides a direct measure of the temperature ranges for which the caps are able to prevent evaporation during RTP. In addition, kinetic studies of the evaporation at slightly higher temperatures provides information useful for establishing the predominant evaporation mechanism. For the encapsulants studied, these measurements indicate that the observed evaporation is due to formation of cracks in the film during the initial 10 sec of RTP.
The Effect of Implantation and Annealing Conditions on the Fe Profile in Semi-Insulating InP.
Authors: Bahir G. , Merz J. L. , Abelson J. R. , Sigmon T. W. 
Published: March 2011

AbstractThe Fe depth distribution has been measured in semi-insulating (SI) InP implanted with Si as a function of implant temperature and post-implant annealing technique (either furnace annealing or rapid thermal annealing). Depth profiles obtained by secondary ion mass spectrometry and Rutherford backscattering measurements of the damage demonstrate that Fe redistributes into regions of residual damage during thermal processing. These results are interpreted in terms of implantation-related damage effects and the stoichiometry imbalance induced by the Si implantation.
Mechanisms for the Deposition of Thin Metallic Films by Laser Driven Gas Phase Reactions
Authors: Jervis T. R. , Menon S. K. , Joyce E. L. , Carroll D. W. 
Published: March 2011

AbstractGas phase processing rakes laser deposition over large areas possible but homogeneous nucleation of large atomic clusters must be avoided if films are to be produced. Clusters can be highly variable in size from a few atoms to significant fractions of a micrometer. If conditions do not allow for complete quenching of the clusters produced in the gas phase, these clusters can arrive at the substrate with sufficient energy to self sinter into homogeneous films which are substantially different from metallic films grown by thermal techniques. Using transmission electron microscopy (TEM), we have characterized the microstructure of thin metallic films deposited by laser breakdown chemical vapor deposition and identified a range of deposition conditions which can lead from powders to homogeneous polycrystalline films and mixed phase materials. Gas phase nucleation is dependent on reactant partial pressures and the gas phase quench rate which car be varied in part by adjusting the H2 content of the source gas. Manipulation of these parameters can vary powder size from about one micrometer to less than 2 nanometers. Variation of the quench rate during the deposition of polycrystalline films varies the grain size in the films. heating the substrate drastically changes the conditions under which the film is formed and as a consequence, can radically alter the microstructure of the film itself.
Laser-Induced Deposition of Gold Micropatterns from Metallopolymer Thin Films: A Photochemical Approach
Authors: Houlding V. H. , Clements N. S. , Beeson K. W. , West G. A. 
Published: March 2011

AbstractThe deep ultraviolet (250 nm) photopatterning of spin-on films of polymeric Au mercaptide results in formation of adherent Au patterns. Fxcimer laser projection patterning and standard contact printing techniques give excellent pattern resolution on the micron scale. Laser direct write produces lines at very fast writing speeds. Exposed areas are less soluble than unexposed areas, i.e. the film behaves as a negative photoresist. Bakeout of developed patterns at 250°C yields good purity Au micropatterns up to 500 Å thick. Mechanistic information about pattern formation is gained from uv-visible, infrared, and mass spectrometric monitoring of the photolysis process, and from Auger analysis of films. Adherent patterns are apparently formed by photochemical cleavage of Au-S bonds followed by evaporation of a small amount of free mercaptide. The loss of ligand in the exposed areas renders them less soluble than unexposed film. Thermal decomposition of both photolyzed and unphotolyzed films has the same result of volatilizing all film material except Au.
UV Laser-Induced Metal Deposition on Semiconductors From Electroplating Solutions
Authors: Zahavi Joseph , Pehrsson Pehr E. 
Published: March 2011

AbstractWe have demonstrated metal deposition on semiconductors immersed in electroplating solution by exposure to UV laser radiation. N-type β-SiC and Si in gold or Pd/Ni electroplating solutions were exposed to 20 ns pulses of 193 nm or 248 nm excimer laser radiation. The energy per pulse was 20–100 mJ. Au and Pd/Ni metallizations deposited in lines and circles on SiC showed leaky Schottky barrier I-V characteristics. The thickness increased with increasing pulse energy or number. Both masked and maskless deposition were demonstrated without apparent damage to the substrate. Details of the process, potential mechanisms, and sample characterization are discussed.
Characterization of Excimer Laser Deposited Gaas Films From the Photolysis of Trimethylgallium and Trimethylarsine At 193 nm
Authors: Mccrary V. R. , Donnelly V. M. , Brasen D. , Appelbaum A. , Farrow R. C. 
Published: March 2011

AbstractThe growth of GaAs thin films from the excimer laser photolysis of trimethylarsine (TMAs) and trimethylgallium (TMGa) at 193 nm is reported. Scanning electron microscopy (SEM), electron channeling, Rutherford backscattering spectroscopy (RBS), transmission electron microscopy (TEM), and Auger electron spectroscopy (AES) were used to characterize the films. Incident laser fluences on the surface of 0.096–0.115 J/cm2 lead to carbon desorption, adatom mobility, transient annealing and hence epitaxial growth. However, TEM micrographs also revealed the growth of GaAs twins along the <110> direction in a novel periodic fashion, with a spacing equal to that of the ArF excimer laser wavelength (193 nm). Time-resolved mass spectrometry, used to determine gas-phase photolysis products created during the deposition process, showed that AsCH3 and higher gallium-alkyls are significant products which transport As and Ga to the surface.
Excimer Laser Assisted Deposition of GaAs, AlAs, and [Al.Ga]as from Lewis Acid-Base Adducts
Authors: Zinck J. J. , Brewer P. D. , Jensen J. E. , Olson G. L. , Tutt L. W. 
Published: March 2011

AbstractLaser-assisted deposition of GaAs, AlAs and [AIGa]As thin films on Ge(100) substrates from trimethylgallium-trimethylarsenic and trimethylaluminumtrimethylarsenic Lewis acid-base adduct source materials is reported. A parametric study has been performed in which reactive gas pressure, substrate temperature, laser fluence, laser wavelength (248 nm or 193 nm). and orientation of the laser beam with respect to the substrate have been varied. In the case of irradiation parallel to the substrate, stoichiometric films of GaAs and [AIGa]As have been obtained. The data suggest that for irradiation perpendicular to the substrate a competition exists between desorption and photodeposition, which adversely affects film stoichiometry under the conditions studied.