bluuebunny/crossref_metadata_2025_split huggingface dataset:
Laser Deposition of CdS Thin films on Various Substrates
Authors: Shi L. , Hashishin Y. , Dong S. Y. , Kwok H. S. 
Published: March 2011

AbstractWe have deposited CdS thin films onto substrates such as glass, sapphire and high Tc YBCO superconducting films by Nd:YAG laser evaporation in a vacuum environment. X-ray diffraction, optical and electrical measurements were used to study the deposited CdS films. The films are highly oriented with c-axis perpendicular to the surface and are optically smooth. The effects of laser fluence, substrate temperature on the film quality will be discussed. Additionally, Indium doped CdS films were also grown on sapphire substrates by laser deposition. In-situ resistivity measurements were employed to study the film formation process during laser deposition. A simple model was given to explain the in-situ resistivity data. Finally, a deposition temperature window was found to produce good quality CdS/YBCO heterostructures. The superconducting transition temperature of the YBCO films was degraded to 68K from an original Tc of 85 K after CdS deposition. The degradation of the superconducting properties was found mainly due to the interactions in the interface region.
Crystallization of Molybdenum Disulfide Films Deposited by Pulsed Laser Ablation
Authors: Zabinski J. S. , Donley M. S. , John P. J. , Dyhouse V. J. , Safriet A. J. , McDevitt N. T. 
Published: March 2011

AbstractPulsed laser ablation (PLA) is an emerging technology that provides a mechanism to deposit lubricious films and to tailor film properties by the appropriate choice of substrate materials, deposition parameters and post deposition treatments. The properties of MoS2 films deposited by PLA are evaluated as a function of: (1) substrate material, (2) duration of post deposition annealing treatments using 248 nm laser radiation and (3) substrate temperature during deposition. The chemistry and crystal structure of the different films are determined using small angle X-ray diffraction (XRD), Raman spectroscopy, X-ray photoelectron spectroscopy (XPS) and Rutherford backscattering spectroscopy (RBS). The tribological properties of the films are then evaluated as a function of their chemistry and crystal structure.
Stratified Ion Damage and in Situ Regrowth in GaAs/AlAs Heterostructures
Authors: Cullis A G , Eaglesham D J , Jacobson D C , Poate J M , Whitehouse C R , Smith P W 
Published: March 2011

AbstractThe material-dependent manner in which ion damage occurs in AlAs/GaAs heteroepitaxial structures is demonstrated using conventional and high resolution transmission electron microscopy. Both 150keV and 2MeV Si+ ion implants are employed over a wide range of ion doses. Under conditions which yield rapid build-up of lattice damage in GaAs, the AlAs is found to be relatively resistant to structure breakdown. Indeed, the crystalline AlAs exerts a novel protective effect on immediately adjacent regions of the GaAs layers. For high implantation doses amorphous-crystal superlattices are formed in multilayer structures. For the highest ion doses the AlAs lattice begins to be disrupted by a characteristic, boundary-dependent, heterogeneous mechanism. These observations suggest that mobile point defects play a significant role in AlAs in situ restructuring processes.
Structural and Electrical Properties of Tin and Carbon Co-Implanted Silicon
Authors: Mei P. , Schmidt M. T. , Li P. W. , Yang E. S. , Wilkens B. J. 
Published: March 2011

AbstractThe alloy system Six(SnyC1-y)1-x was investigated. In this work, samples were prepared by co-implantation of tin and carbon ions into silicon wafers with dosage range 1015 − 1016cm−2, followed by rapid thermal annealing. Rutherford backscattering channeling, Auger sputter profiling, and secondary ion mass spectrometry were employed to study the crystallinity, chemical composition and depth profiles. A near perfect crystallinity for 0.5% at. of tin and carbon was achieved. To study the electrical properties in the implanted materials, diode I-V measurements were performed. The data show near ideal p-n junctions in the co-implanted region. This work demonstrates promising features of group IV semiconductor synthesis by ion implantation.
Incorporation of Ambient Oxygen During Silicon Deposition and the Effects of Argon Ion Bombardment
Authors: Brown David W. , Hubler Graham K. 
Published: March 2011

AbstractThe composition of SiOx films deposited by electron-beam evaporation of silicon in an oxygen atmosphere was measured as a function of silicon deposition rate and oxygen pressure. The compositions varied between X = 0.03 and 2.1 depending on the ratio of O2 molecules to Si atoms arriving at the substrate. Bombardment with 500 eV argon ions caused X to decrease at low arrival ratio and to increase at higher arrival ratio. The results are analyzed using an adsorption model in which chemisorption of O2 occurs after physisorption into one of two states: one on silicon and one on SiO2. A fit to the data for the unbombarded samples is achieved if physisorption occurs only on silicon. From this fit a sticking coefficient of 0.05 is obtained for O2 chemisorption on silicon. The effects of ion bombardment are consistent with the model if bombardment allows O2 to also physisorb on SiO2 and migrate to silicon where it chemisorbs.
Self Annealing Ion Implantation in thin Silicon Films
Authors: Rubio J. D. , Vijay R. P. , Hart R. R. 
Published: March 2011

AbstractThe self annealing phenomenon was studied utilizing 1 cm diameter, 1 μm thick, <100> oriented silicon films. Previous results established the viability of the self annealing process for medium energy argon beams incident on similar targets [1]. In the current work, doubly aligned backscatter spectra were obtained to improve the sensitivity of the residual lattice damage measurements. In addition, some implantations were performed at elevated temperatures to independently determine the effect of the flux and the sample temperature on the self annealing process. The results showed strong correlations between the implantation flux, sample temperature and the residual lattice damage. Two distinct temperature regions were observed above and below 330 °C with corresponding activation energies of 1.5 eV and 0.1 eV.
High Dose Rate Oxygen Implantation for Formation of Silicon-on-Insulator Structures
Authors: Cortesi E. , Namavar F. , Pinizzotto R. F. , Yang H. 
Published: March 2011

AbstractWe have studied Separation by IMplantation of OXygen (SIMOX) processes using very high dose rates (40–60 μA/cm2). For a dose of 4 × 1017 O+/cm2 at 160 keV, the structure formed by implantation at 50 μA/cm2 is very similar to that associated with lower dose rates. The same dose implanted at a dose rate of 60 μA/cm2, however, results in the formation of pits in the silicon surface as well as a somewhat different oxide structure. Implantation through a surface oxide layer appears to result in a structure similar to that associated with lower dose rate implantation. These and higher dose samples suggest that the threshold for pit formation is related to both dose rate and dose.
Superconducting YBaCuO thin Films by Cu-Ion Implantation
Authors: Hubbard Kevin M. , Bordes Nicole , Nastasi Michael , Tesmer Joseph R. 
Published: March 2011

AbstractWe have investigated the fabrication of thin-film superconductors by Cu-ion implantation into initially Cu-deficient Y(BaF2)Cu thin films. The precursor films were co-evaporated on SrTiO3 substrates, and subsequently implanted to various doses with 400 keV 63Cu2+. Implantations were preformed at both LN2 temperature and at 380°C. The films were post-annealed in oxygen, and characterized as a function of dose by four-point probe analysis, X-ray diffraction, ion-beam backscattering and channeling, and scanning electron microscopy. It was found that a significant improvement in film quality could be achieved by heating the films to 380°C during the implantation. The best films became fully superconducting at 60–70 K, and exhibited good metallic R vs. T. behavior in the normal state.
Ion Beam Synthesis of Buried Single Crystal Erbium Silicide
Authors: Golanski A. , Feenstra R. , Galloway M. D. , Park J. L. , Pennycook S. J. , Harmon H. E. , White C. W. 
Published: March 2011

AbstractHigh doses (1016–1017/cm2) of 170 keV Er+ were implanted into single-crystal 〈111〉Si at implantation temperatures between 350°C and 520°C. Annealing at 800°C in vacuum following the implant, the growth and coalescence of ErSi2 precipitates leads to a buried single crystalline ErSi2 layer. This has been studied using Rutherford backscattering/channeling, X-ray diffraction, cross-sectional TEM and resistance versus temperature measurements. Samples implanted at 520°C using an Er dose of 7 × 1016/cm2 and thermally annealed were subsequently used as seeds for the mesocpitaxial growth of the buried layer during a second implantation and annealing process. Growth occurs meso-epitaxially along both interfaces through beam induced, defect mediated mobility of Er atoms. The crystalline quality of the ErSi2 layer strongly depends on the temperature during the second implantation.
Effect of Ion Implantation on YBCO Superconductor Thin Film
Authors: Zhang Zuhua , Liu Jiarui , Bui Ma Ki , Wu J. , Yu Ning , Zhao Yuan-Jun , Lam W. A. , Hsieh P. Y. , Chu Wei-Kan 
Published: March 2011

AbstractThe effects of the H+. C+. N+, F+, and Ne+ (25–200 keV)ion irradiations have been investigated by means of SEM, room temperature resistance measurement and aqueous degradation test. The room temperature resistance increases exponentially with irradiation doses. At lower dose, the annealing process is dominent, while at higher dose, the resistance increasing process is dominent. A reduction in the thickness induced by ion irradiation has been observed. The aqueous experiment shows that passing current will speed up the degredation and N+ implantations can increase the resistance of the YBCO thin film against attack by water.
Damage Accumulation and Annealing in Ion Irradiated Silicon
Authors: Priolo F. , Battaglia A. , Spinella C. , Rimini E. 
Published: March 2011

AbstractThe evolution of pre-existing damage structures in Si under high energy ion irradiation is discussed. Different initial morphologies are investigated: a sample partially pre-damaged with heavy ions and a sample partially pre-damaged with light ions are compared within them and with an undamaged single crystal. It is shown that ion irradiation can produce either damage accumulation, in the form of amorphous regions, or damage annealing depending on the pre-existing damage morphology, on the substrate temperature, and on the doping content in the irradiated layer. These data are discussed and interpreted on the basis of the existing models on ion induced amorphization and crystallization.
Ion-Surface Interactions During Epitaxy
Authors: Barnett S. A. , Choi C.-H. , Kaspi R. 
Published: March 2011

AbstractRecent work on low-energy ion-assisted deposition of epitaxial films is reviewed. Much of the interest in this area has centered on the use of very low ion energies (∼ 25 eV) and high fluxes (> 1 ion per deposited atom) obtained using novel ion-assisted deposition techniques. These methods have been applied in ultra-high vacuum, allowing the preparation of high-purity semiconductor materials. The following ion-surface interaction effects during epitaxy are discussed: improvements in crystalline perfection during low temperature epitaxy, ion damage effects, improved homogeneity and properties in III-V alloys grown within miscibility gaps, and changes in nucleation mechanism from Stranski-Krastanov to layer-by-layer.
Dynamics Of MoS2 Photoablation
Authors: Murray P. T. , Dyhouse V. J. , Grazulis L. , Thomas D. R. 
Published: March 2011

AbstractSpeed distributions were determined for the ions ejected from MoS2 by excimer laser ablation. It was found that the majority of ionic species were atomic and were ablated with speeds in excess of 6 km/s. The speed distributions were found to be non-Maxwellian and were best described by a supersonic expansion model. The differences in ArF and KrF excimer laser ablation are discussed.
Channeling Study of Partially Ionized Beam Deposited Epitaxial Ag Films on Si(111) Substrates
Authors: Jin H.-S. , You L. , Lu T.-M. 
Published: March 2011

AbstractAg films deposited on Si(111) substrates by partially ionized beam (PIB) under conventional vacuum conditions were studied by MeV ion channeling techniques. In spite of their large lattice mismatch (24.8%), Ag films were still found to be epitaxial. With a deposition temperature of 350°C and without post-annealing, the Xmin value at the surface of a 2550 A° thick Ag film was found to be 10%. The azimuthal angular scan and the measured axial channeling dip showed that the Ag film was (111) oriented. The lattice quality of the films was comaparable to that deposited by MBE techniques. Dislocations were found in the PIB deposited Ag films. Lattice damage due to the bombardment of energetic ions was also observed. The thickness of the Ag film was found to have a pronounced effect on the crystalline quality at the surface. With the thickness increasing from 1240 A° to 2550 A°, the lattice quality at the Ag surface improved significantly, but not much change in the defect density in the Ag films was obseved.
Agglomeration of Cobalt Silicide Films
Authors: Xiao Z. G. , Rozgonyi G. A. , Canovai C. A. , Osburn C. M. 
Published: March 2011

ABSTRACTThe agglomeration of Co silicide films formed on Si substrates processed with different Co film thickness was investigated by TEM, XRD, and four-point-probe measurements. It was found that thermal grooving always accompanies the film formation, while islanding can occur during high temperature thermal stability testing, or during formation of very thin films at moderate temperatures. In addition to whole film agglomeration, partial agglomeration on the top of the film has been observed, which is prominent and important for thin films. A theoretical model of agglomeration for silicide films is presented, which shows that when the ratio of grain size to film thickness is smaller than a critical value, the film will not lose its continuity. Also, grain boundary migration was found to have a suppressing effect on thermal grooving. Both a small grain size and a low grain boundary energy are shown to be favorable for improving the thermal stability.
Microstructural Evolution of Fe Grown on a (001) Cu Film and its Implication to the Elastic Anomaly in Metallic Superlattices
Authors: Koike J. , Nastasi M. 
Published: March 2011

ABSTRACTA large softening of the shear modulus has been reported in metallic superlattices composed of insoluble bcc/fcc metals. In an attempt to understand this elastic anomaly, we have studied the microstructure of Fe/Cu bilayers as a function of the Fe thickness with transmission electron microscopy (TEM). Analysis of the moire fringes observed in plan-view TEM images revealed that the fee Fe structure epitaxially grows on the (001) Cu up to a thickness of 2.0 nm. At 2.3 nm, the bec Fe structure nucleates, accompanying lattice rotation around the growth direction with respect to the underlying fee structure. As the Fe thickness further increases, submicron polycrystalline grains formed. Based on these results, the microstructure of the metallic superlattices and its relation to the softening of the shear modulus will be discussed.
Microstructural Development in Ion Beam Assisted Evaporation of Ni, Co and Fe Films
Authors: Trogolo J.A. , Roy R.A. , Petkie R. , Cuomo J.J. , Rajan K. 
Published: March 2011

ABSTRACTThe development of microstructure in metal films deposited by ion-assisted evaporation has been studied by transmission electron microscopy (TEM). Films of Ni, Co, and Fe of about 350 to 500 nm thickness were deposited by electron beam evaporation with concurrent argon ion bombardment during growth. Films grown at high ion/atom ratios develop compressive stress as revealed by lattice dilatation. The trends in grain size, orientation, and shape as a function of ion bombardment are documented by TEM.
Vapor Deposited Thin Films and Their Densification During Ion Beam Assisted Deposition
Authors: Andreadis T.D. , Rosen Mervine , Haftel M.I. , Sprague J.A. 
Published: March 2011

ABSTRACTA computer simulation is presented of the reduction of void volume by incident energetic ions during Ion Beam Assisted Deposition (IBAD) of thin Ge films. The objective of the work is to understand the important mechanisms of thin film densification during IBAD. The density is affected by a number of mechanisms including: absorption of recoil atoms by voids and by diffusion of residual interstitials and vacancies. Simulations of Ge deposition under Ar ion bombardment were made using the collision cascade code MARLOWE with realistic void-sizes and for beam energies up to 500 eV. MARLOWE was used to obtain void volume loss as a function of void depth, void volume, and ion energy. The fate of residual interstitials and vacancies is taken into account.In order to model IBAD it is important to be able to model the deposition process. We describe our three-dimensional Molecular Dynamics simulations of the vapor deposition of Ni on a Ni (100) surface under low atom mobility conditions. We found the deposited film to have a packing density of about 80% of the nominal value and to contain ribbon-like voids.
High Resolution Plan View Imaging of Clean and Au Deposited Si(111) Surfaces
Authors: Ozawa S. , Tanaka Y. , Kobayashi K. , Yamamoto N. , Yagi K. 
Published: March 2011

ABSTRACTHigh resolution plan view images of clean and Au deposited Si(111) surfaces are presented. Corner holes and small holes between dimers of the DAS model of the 7×7 structure were clearly resolved. In the case of the Si (111) 5×1-Au structure the 5 times period fringes did not show fine details.
Kinetics of Molecular Beam Epitaxy: Effect of Ion-Induced Sputtering
Authors: Richards Peter M. 
Published: March 2011

ABSTRACTSteady state roughness of surfaces growing by molecular beam epitaxy is investigated by Monte Carlo simulations under conditions where an ion beam is also present which sputters adatoms off the surface. If the sputtering is random, it only increases the roughness. But if the sputtering probability is strongly dependent on the binding energy of an adatom within a cluster or island, the ions can have a smoothening effect. Physical arguments are given in support of the results.
Improvement of Gaas Crystal Quality on Si Grown by Mocvd Through Two-Dimensional-Like Nucleation with Low Temperature in Situ Hydrogen/Arsine Plasma Cleaning
Authors: Yoon Euijoon , Reif Rafael 
Published: March 2011

ABSTRACTWe report the significant improvement of GaAs crystal quality on Si grown by metal-organic chemical vapor deposition (MOCVD) with an in situ low temperature hydrogen/arsine plasma cleaning of the Si substrate at 450°C and a consequent controlled two-dimensional-like morphology of the low temperature buffer layer at its early stage. The most critical step that determines the interfacial cleanliness and the early stages of the nucleation and thin film formation of heteroepitaxial GaAs on Si in a non-ultrahigh vacuum MOCVD system is the substitution of hydrogen atoms passivating the Si surface after ex situ HF-dip with pas-sivating As atoms. Reduction of in situ cleaning temperature ensures the very slow kinetics of thermal desorption of the hydrogen atoms and re-oxidation of exposed Si surface from the reactor environment, and provides a fully As-passivated Si surface, leading to a 2D-like buffer layer.
Dynamics of Mbe Growth Surface Roughening of Ge (001) - A Stochastic Model Study
Authors: Khoie Venkatasubramanian R. , Khoie Rahim 
Published: March 2011

ABSTRACTA stochastic model for the MBE growth of Ge is developed based on the master equation approach with solid-on-solid restriction and quasi-chemical approximation. The surface kinetic processes included are: adsorption, evaporation and intralayer and interlayer migrations. The growth rate, the average surface roughness and the average intensity of reflection high energy electron diffraction (RHEED) (using kinematical theory of electron diffraction’ were obtained for the MBE growth of Ge with the temperature in the range 100-500°C and a typical flux of 1 Å/sec. The average surface roughness and the growth rate are found to be independent of substrate temperature below 150°C and above 400°C. In the intermediate temperature range, the growth rate increases and the surface roughness decreases with increasing temperature. The kinetic roughening temperature above which a smooth surface remains smooth, is identified from the temperature depen-dance of the average surface roughness and RHEED intensity, as 400°C. The temperature dependance of the average RHEED intensity and the kinetic roughening temperature obtained from this study compare favorably with the experimental results. At low substrate temperature, the surface migration rate is negligible irrespective of the temperature and therefore, the surface roughness and the growth rate become independent of the growth temperature. At high substrate temperatures, the surface roughness and the growth rate attain the limiting values for the flux chosen, owing to the saturation of the available sites for the interlayer migration process. Thus, these parameters become independent of the growth temperature.
Initial Stages of Gaas Growth on Scl-XErxas Surfaces
Authors: Finstad Terje G , Palmstrøm C. J. , Mounier S. , Keramidas V. G. , Zhu J. G. , Carter C. B. 
Published: March 2011

ABSTRACTLattice matched ScxEr1-xAs (ScErAs) was grown on GaAs by MBE followed by a GaAs overlayer. The overgrowth of GaAs on ScErAs has been studied by Reflection High Energy Electron Diffraction (RHEED), Low Energy Electron Diffraction (LEED), Auger Electron Spectroscopy (AES), Nomarskii-interference microscopy and Transmission Electron Microscopy (TEM). In this study substrate temperature and crystal orientation have been varied. For GaAs growth on (100)ScErAs there is a strong tendency for island formation and three dimensional (3D) growth. For high substrate temperatures (>500 °C) and for moderate growth rates (10 ML/min) the growth can be described by the Volmer-Weber mode. For lower substrate temperatures we observe that one monolayer of GaAs on ScErAs is metastable. This monolayer shows a (3×1)/(1×3) surface reconstruction. The deposition of more than one monolayer, irrespective of substrate temperature, or the raising of the substrate temperature induces island growth. The metastable reconstructed surface layer of GaAs then partly dissolves into the islands. The strong tendency for 3D growth observed here is very similar to that seen in the growth on ErAs which is not lattice matched to GaAs. This observation demonstrates the significance of electronic bonding mismatch over lattice mismatch for heteroepitaxy between materials with ionic and covalent bonding character. Growth on {111}-polar surfaces yields smoother layers and a stronger tendency for 2D growth.