bluuebunny/crossref_metadata_2025 huggingface dataset:
Microstructure and Composition of Surface Layers Formed by Ion Implantation of Nitrogen in High-Purity Aluminum
Authors: Mccune Robert C. , Donlon W. T. , Plummer H. K. , Toth L. , Kunz F. W.
Published: March 2011

Surface layers with overall thickness <∼300 nm were produced by ion implantation of N+ or N2+ at energies of 50 or 100 keV in 99.99% pure aluminum. These surfaces were characterized by scanning and transmission electron microscopy, Auger electron spectroscopy, Rutherford backscattering, nuclear reaction analysis and particle-induced X-ray analysis. At doses above 2×1017 N2/cm2 , blistering of the surfaces was observed along with a reduction in the extent of the coulometric dose retained by the material. Oxygen is believed to be introduced into the near-surface region by a process of reaction and ion-beam mixing, as well as possible CO contamination of the beam. A phase, isostructural with AlN, forms semi-coherently with parent aluminum grains, however, some fraction of the metallic aluminum phase remains in the reaction layer, even at overall nitrogen contents which exceed the stoichiometry of AlN.
Ion Implantation Damage in Aluminum Studied by Quantitative Electron Chanelling and Tem.
Authors: Vardiman Ronald G.
Published: March 2011

Electron chanelling linewidth changes in aluminum have been measured as a function of dose for boron and aluminum ion implantation. Weak beam TEM observations assist interpretation of the results by showing the nature and degree of the damage. For self implantation, a linear relationship between dose, linewidth, and dislocation density has been found up to 3×1017ions/cm2. For boron implantation, a new point-like defect appears at the higher boron concentrations, giving a much slower increase of chanelling linewidth with dose above l×1016 ions/cm2. Boron interaction with the damage stabilizes higher damage acumilations than for sel f-i mpl antati on.
Nitrogen and Carbon Solute Redistribution During High Fluence Nitrogen Implantation into Iron
Authors: Ehni P. D. , Singer I. L. , Hues S. M.
Published: March 2011

Model solute distribution studies have been performed in N-implanted Fe. Concentration-verses-depth profiles have been determined by secondary ion mass spectroscopy for Fe implanted to low fluences with isotopes 13C at 190keV and 15N at 180keV followed by 14N to high fluences. At N fluences greater than 2.5 × 1017 /cm2 dramatic changes in the 13C and 15N profiles are observed. It is proposed that these changes are caused by the lattice dilation due to precipitation of iron nitrides.
Enhanced Oxidation of TiSi2 Films by As+ Implantation
Authors: Holland O. W. , Fathy D.
Published: March 2011

The influence of As+-ion implantation on the oxidation of TiSi2 films is investigated. It will be shown that implantation leads to a greatly increased rate of oxidation in a dry O2 ambient. Low-temperature oxidation of the implanted films not only results in substantial oxidation of the films, but completely alters the films' morphology. Different implantation techniques were used to isolate the effects of ion-induced damage from chemical effects, so that each could be separately studied. It will be shown that neither chemical nor damage effects are able, by themselves, to account for the enhanced oxidation. Rather, a model is proposed to explain the role of implantation in the oxidation process which depends on a synergistic relation between these two effects.
Capacitance Spectroscopy of Schottky Diodes Formed on Ion-Etched GaAs
Authors: Sen S. , Cole E. D. , Burton L. C.
Published: March 2011

DLTS and low frequency capacitance measurements were made on Schottky diodes formed on Ion-beam etched (IBE) GaAs surfaces. Ion bombardment causes strong low frequency capacitance dispersion, increasing with ion energy. This is attributed to a thin, heavily damaged region, with a trap density in excess of 1017 per cm3. Such dispersion disappears under weak reverse bias and at reduced temperatures. These and other measurements are consistent with a lumped R-C model having components representing the top damaged layer, the underlying space-charge region, and shunt resistance to the ohmic contact.
Synthesis of Buried Silicon Compounds Using Ion Implantation
Authors: White Alice E. , Short K. T. , Dynes R. C. , Gibson J. M. , Hull R.
Published: March 2011

Ion implantation is widely used for doping semiconductors at low concentration, but, with the advent of a new generation of high current implanters, synthesizing new materials rather that simply doping them has become feasible. This technique has been successfully applied to fabricating silicon-on-insulator (SOI) structures with oxygen and nitrogen for several years. Since we are interested in understanding the mechanisms of formation of these layers, we have concentrated on sub-stoichiometric implantation doses of oxygen where it is easier to observe the coalescing layer. In order to determine whether this process of compound formation is more general, our studies were expanded to include implantation of the transition metals. Here, elevated substrate temperatures are necessary to minimize Si surface damage. The resulting disilicide layers are of remarkably high quality: they are single crystals in registry with the silicon wafer and they have better residual resistivities than comparable UHV-reacted silicides.
Optical Waveguide Formation by Ion Implantation of Ti or Ag
Authors: Poker D. B. , Thomas D. K.
Published: March 2011

Ion implantation of Ti into LINbO3 has been shown to be an effective means of producing optical waveguides, while maintaining better control over the resulting concentration profile of the dopant than can be achieved by in-diffusion. While undoped, amorphous LiNbO3 can be regrown by solid-phase epitaxy at 400°C with a regrowth velocity of 250 Å/min, the higher concentrations of Ti required to form a waveguide (∼10%) slow the regrowth considerably, so that temperatures approaching 800°C are used. Complete removal of residual damage requires annealing temperatures of 1000°C, not significantly lower than those used with in-diffusion. Solid phase epitaxy of Agimplanted LiNbO3, however, occurs at much lower temperatures. The regrowth is completed at 400°C, and annealing of all residual damage occurs at or below 800°C. Furthermore, the regrowth rate is independent of Ag concentration up to the highest dose implanted to date, 1 × 1017 Ag/cm2. The usefulness of Ag implantation for the formation of optical waveguides is limited, however, by the higher mobility of Ag at the annealing temperature, compared to Ti.
Defect Dynamics in Amorphous Silicon – the Recrystallization Process
Authors: Pantelides Sokrates T.
Published: March 2011

The mechanism that underlies the recrystallization of amorphous silicon tas not been established. It is generally argued, however, that the rearrangement of the network occurs through the breaking of bonds or the introduction of vacancies and that this step is responsible for the observed activation energy (∼2.5 eV). It is suggested here that the rearrangement of the network is accomplished through the migration of intrinsic overcoordination defects (“floating bonds”) and that this process has a small activation energy (∼0.4 eV). The observed large activation energy is actually due to a reaction that inhibits recrystallization. This reaction may be the elimination of preexisting dangling bonds.
Ion Beam Induced Regrowth in GaAs
Authors: Johnson S. T. , Williams J. S. , Nygren E. , Elliman R. G.
Published: March 2011

Ion implanted, amorphous layers on (100) GaAs have been recrystallised epitaxially by 1.5 MeV Ne+ irradiation at temperatures between 75°C and 135°C. The extent of regrowth essentially increases linearly with ion fluence in the early stages of crystallization and the process is characterized by an activation energy of 0.16eV, about an order of magnitude lower than that for thermal - only epitaxy. Beam annealing produces dislocations in the underlying GaAs crystal, the density of which increases with depth up to the Ne+ ion range.
Femtosecond Carrier Dynamics in Semiconductors and Metals
Authors: Lin Wei Zhu , Schoenlein Robert W. , Brorson Stuart D. , Ippen Erich P. , Fujimoto James G.
Published: March 2011

We describe investigations of carrier dynamics in GaAs and AlGaAs semiconductors and thin gold films using femtosecond optical techniques. Transient absorption saturation measurements in semiconductors permit an investigation of the fundamental scattering processes of optically excited carriers. Measurements of energy relaxation provide evidence for transient nonthermal carrier distributions. Studies in metals allow an investigation of nonequilibrium electron and phonon effects since the electrons are decoupled from the lattice on a femtosecond time scale. Nonequilbrium temperatures and energy transport in the electron gas have been observed.
Picosecond Laser-Induced Solid-Liquid Phase Transformations in Gallium Arsenide and Silicon
Authors: Danielzik B. , Harten P. , Sokolowski-Tinten K. , Linde D. von der
Published: March 2011

Melt-in velocities of picosecond laser-heated Si and GaAs were obtained from optical reflectivity measurements. We observed a velocity increase from about 100 m/s near the melting threshold to many hundred m/s at higher fIuences. With a new technique for picosecond time-resolved observation of atomic desorption we have been able to resolve the evaporation of Ga.
Effect of Density Change on Rapid Liquid-Solid Interface Kinetics and Heat Flow
Authors: Richards Peter M.
Published: March 2011

Consequences of the need to transport density to or from a fast-moving liquid-solid interface are examined. There can be a severe limitation of the freezing velocity and a change in the amount of heat which must be conducted. The latter effect produces a net latent heat which can be significantly different from the equilibrium value and even change sign.
Excimer Laser Mixing of Titanium Layers on AISI 304 Stainless Steel
Authors: Jervis T. R. , Nastasi M , Zocco T. G.
Published: March 2011

We have used excimer laser radiation to mix single layers of Ti directly on annealed substrates of 304 stainless steel. This process produces much thicker surface alloy layers and is much faster than ion mixing techniques. Liquid state diffusion results in mixed layers of the order of 1.0 μm thick from 0.5 μm Ti overlayers. In single pulse experiments, fluences of up to about 4 times melt threshold could be used before ablation occurred. The fluence in these experiments determines the melt duration and therefore the amount of mixing. In order to achieve greater mixing without ablation of the surface, multiple pulses at lower fluence were used. Profiles of laser mixed surface layers and microstructural characterization of the layers are presented.
Threshold for Single Excimer Laser Pulse Backside Removal of Thin Metal Films from Optical Quartz
Authors: Baseman R. J. , Andreshak J. C.
Published: March 2011

The minimum energy in a 248 nm, 25 ns long excimer laser pulse required to remove thin Au and Cr films from optical quartz has been measured. Heating of the films by the laser has been modelled with a finite element calculation. Assuming that at threshold, all of the laser energy contributes to film removal, the calculations show that the gold films are removed when the heated gold surface reaches the atmospheric boiling point, and that temperatures well in excess of the atmospheric boiling point are required to remove the Cr films, with the required temperatures increasing with film thickness.
Interpretation of Time-of-Flight Distributions Resulting from Pulsed Laser-Induced Desorption
Authors: Buck M. , Hess P.
Published: March 2011

Time-of-flight (TOF) experiments were performed to study the desorption of trans-l,2-dichlorocyclohexane molecules from molecular films condensed on a quartz-crystal microbalance at 77 K. The wavelength dependence of the desorption signal was investigated by resonant excitation of the internal vibrational mode of the molecule in the 10 μm region with a pulsed line-tunable TEA CO2 laser. The TOF temperatures showed the same spectral dependence as the optical absorption coefficient. The TOF distributions were narrower than Maxwellian distributions for multilayer desorption yields and approached Maxwellian distributions for submonolayer desorption yields. A saturation behavior was found at high laser intensities, indicating that the kinetic energy of the desorbing molecules is limited to a maximum value.
Nmos Transistors Fabricated by Simultaneous Laser-Assisted Crystallization and Diffusion on Silicon on Electro-Optic PLZT
Authors: Wang J. H. , Lin T. H. , Esener S. C. , Dasgupta S. , Lee S. H.
Published: March 2011

Simultaneous CW laser assisted crystallization and diffusion for fabricating NMOS transistors on Si/SiO2/PLZT is presented. Hall effect measurement (mobility 74cm2V−1sec×1019cm−3 of phosphorus dopping), crystal delineation (grain size 50×30μm) and Raman spectroscopy (stress 6.0×109dynescm−2) indicated that good quality doped silicon crystal film can be produced with this method. NMOS transistors fabricated by this technology show good performances such as high breakdown voltage (45 V), small leakage current (2 nA/μm), reasonable channel carrier mobility (140cm2V−1−1) and photosensitivity (1.5 A/W).
Arsenic Redistribution and Outdiffusion in Implanted Czochralski-Grown P-Type Silicon During Rapid Thermal Annealing
Authors: Chaussemy G. , Canut B. , Kumar S. N. , Barbier D. , Laugier A.
Published: March 2011

The effects of the implantation parameters (dose and energy) on the Arsenic redistribution and outdiffusion rate in (100) p-type silicon, after 7–12 s Rapid Thermal Annealing in the 1100–1200°C temperature range have been investigated. Four doses ranging from 2×1014 to l×1016 cm−2, and As+ energies between 70 and 170 keV, have been studied. The experimental diffusion profiles obtained from the SIMS measurements, in complement with the RBS results, were modelled using the one dimensional Fick's equation with semi-infinite boundary conditions, using a concentration and temperature dependent diffusion coefficient D(C, T). The As diffusivity was classically attributed to As+V0, As+V−, and As+V − pairs with the related diffusion coefficients taken from the literature. A relatively good description of the As redistribution was obtained without introducing any transient or SPE effects.
Redistribution of Dopant and Impurity Concentrations During the Formation of Uniform Wsi2 Films by RTP
Authors: Siegal Michael P. , Santiago Jorge J.
Published: March 2011

Secondary ion mass spectroscopy has been used to study the effects of rapid thermal processing on the formation of tetragonal tungsten disilicide thin films on Si(100), p-type 5 Omaga;, cm wafers. The substrates were chemically etched, followed by an RF sputter depostion of 710Å W metal. The samples were then fast radiatively processed in an RTP system for time intervals ranging from 15 to 45 seconds at high temperature (∼1100°C) under high vacuum.

The redistribution of the boron dopant concentration profile is studied and shows that boron moves from the Si-substrate into the growing Wsi2 film, eventually escaping into the vacuum. Oxygen is the major impurity in these samples and its removal from the interface has been shown to improve the quality of the silicide film. Trace quantities of F, Cl, Na, K, C and Cr have also been detected.
Millisecond Duration Annealing of Boron Implants in Silicon
Authors: Smith D. A. , McMahon R. A. , Ahmed H. , Godfrey D. J.
Published: March 2011

A dual electron beam machine has been used to anneal boron implanted layers in order to study the diffusion and activation behaviour over a wide range of doses. The annealed implants have been characterized by spreading resistance profiling and secondary ion mass spectroscopy (SIMS). Carrier concentration profiles show that millisecond duration anneals can activate boron implants. A boron dose of 1E16 ions/cm2 was annealed to give a sheet resistance of 30 Ωsq with 40% of the implant activated. The SIMS technique showed there were no significant differences between the atomic profiles of the as-implanted samples and specimens subjected to a millisecond anneal or to a low temperature 850°C rapid isothermal anneal for 10s.
Shallow Junctions Formed by the Thermal Redistribution of Implanted Arsenic into TiSi2
Authors: Cao D. X. , Harrison H. B. , Reeves G. K.
Published: March 2011

Following the implantation of arsenic into titanium disilicide films on p type silicon, Rutherford backscattering has shown that rapid thermal vacuum processing (RTVP) causes the arsenic to diffuse toward the silicide/silicon interface, with an accumulation at the interface and with a sharp shallow diffusion into the silicon. The effect of the implant and anneal on the sheet resistance of the silicide and underlying silicon have been investigated’ and it is shown that anneal times of thirty seconds at 900 °C produce acceptable shallow junctions suitable for device type applications without significant deterioration in silicide electrical or physical properties.
Laser Induced Metal Deposition on Semiconductor, Metallic and Polymeric Substrates From Electroplating Solutions
Authors: Zahavi J. , Tamir S. , Rotel M. , Campisi G.J. , Pehrsson P.E. , Halliwell M.
Published: March 2011

This work is aimed at studying the feasibility of laser induced, high-speed, highly selective direct deposition of metals on substrates immersed in commercial electroplating solutions without masking procedures and external electric current.

A Q-Switch Nd/YAG pulsed laser system and excimer UV pulsed laser systems operating respectively at wavelength of 532nm and at 193 and 248nm, were used in conjunction with commercial basic potassium gold cyanide and acidic gold tetrachloride solutions. The substrates were semiconductors (silicon, gallium arsenide and silicon carbide), metallic (platinum) and polymeric (polyimide).

The morphology, structure, composition and properties of the gold deposits were examined by the SEM, TEM, X-ray, AES and ESCA techniques.

Deposits were found to consist of elemental gold with thickness range from a few hundred angstroms to several micrometers, depending primarily on laser energy density and on the number of pulses. Deposition occurred wherever band gap energies (plus surface barrier) were smaller than the laser photon energy; none was observed in reverse situations, as in the cases of Si3N4 and fused SiO2.

The deposits exhibited Schottky barrier contacts on silicon, silicon carbide and gallium arsenide.
Computer Simulation of Laser Induced Temperatures for the Laser Direct Writing technique
Authors: Tonneau Didier , Auvert Geoffroy
Published: March 2011

Laser induced temperatures in substrates irradiated with a scanning gaussian laser beam were calculated by the finite element method. A quartz substrate of a given thickness and covered with a one - micron - thick silicon coating was assumed to be either placed on a heat sink or thermally insulated. The maximum temperature in the center of the laser spot was found to be proportional to the laser power for a spot size larger than the silicon thickness. Furthermore at a given laser power, the temperature decreased with increasing laser spot diameter and the time to reach the equilibrium temperature increases with the spot radius for radii less than the substrate thickness. The laser induced temperature was found to be affected by laser - scan speeds for speed values above the heat diffusion rate.
Quartz Crystal Microbalance Determination of Laser Photochemical Deposition Rates: Mechanism of Laser Photochemical Deposition From the Group 6 Hexacarbonyls
Authors: Jackson Robert L. , Tyndall George W.
Published: March 2011

A quartz crystal microbalance has been used to measure the rates of focused uv laser-induced deposition from the Group 6 hexacarbonyls in real time. The experimental configuration employs acwuv laser beam focused onto the microbalance crystal surface at normal incidence to deposit material by decomposition of a metal complex vapor. Simple equations are given for determining absolute deposition rates in terms of the total mass deposited per unit time. Kinetic data obtained with this system have been used to study the mechanism of laser photodeposition from Cr(CO)e, Mo(CO)6, and W(CO)é induced by a frequency-doubled argon ion laser. The rate-determining deposition step involves condensation of products formed upon single-photon dissociation of the metal carbonyls in the gas phase. Additional observations indicate that the adsorbed photoproducts undergo further photo-initiated dissociation on the substrate surface.
Microstructure of Gold Films Grown by Ion Induced Deposition
Authors: Ro J.S. , Dubner A.D. , Thompson C.V. , Melngailis J.
Published: March 2011

A beam of ions incident on a substrate can cause adsorbed gas molecules to break up, resulting in material deposition. We have previously demonstrated deposition of gold from a gas of dimethyl gold hexafluoro acetylacetonate (C7H7F6O2Au) using both focused and broad ion beams. Here we investigate growth at various substrate temperatures and examine micro-structure using transmission electron microscopy. Films grown at room temperature were discontinuous even up to the thickness of 250μπι while films grown at higher substrate temperatures were continuous even at lower thicknesses. Deposition carried out on substrates at 100°C and 160°C using 70 kev Ar+ ions resulted in resistivities approaching the bulk value and a deposition yield of 60 to 75 atoms/ion. The relationship between growth conditions, micro-structure and resistivity will be discussed.
Superconductors With Structured Surfaces: Fields and Currents
Authors: Wu Z.C. , Jelski Daniel A. , George Thomas F.
Published: March 2011

This paper discusses the behavior of currents and fields along a structured superconductor. First the effect of surface structure on supercurrents is investigated. Then the effect of structure on the critical nucleation field is discussed in two cases, one with the magnetic field parallel to the ripples and the other with the field parallel to the grating wavenumber. In the first case, it is found that the critical field is reduced as a function of grating height, whereas in the latter case it is increased. Finally, the relevance of this work for laser-induced chemistry above a superconducting surface is discussed. The Ginzburg-Landau model is used throughout.
Photo-Assisted Molecular Layer Epitaxy
Authors: Nishizava Jun-Ichi , KurabayashI Toru
Published: March 2011

Photoexcitation effects of GaAs vapor phase epitaxy have been studied. The growth rate is enhanced by irradiating the substrate zone with an exciier laser irradiation at 2 4 9 n m wavelength, however, the growth rate is reduced by irradiating the source Ga zone with a 249 or 222m exciier laser at températures below 650*C. Because of sharp wavelength dependence and from the result of the theoretical estimations, these effects have been concluded to be caused not by a therma1 -induced reaction but, rather, by photoinduced reactions.

Influence of photoexcitation of the film grown by molecular layer epitaxy has been also studied. Photoirradiation could be independently undertaken at different crystal growth steps, e.g. the irradiation duration could be synchronized with the time duration of each gases supply and exhaust. By this method “synchronized irradiation”, the quality of the epitaxial film and the surface morphology of epitaxial films grown by molecular layer epitaxy were improved.
Photolytic Deposition of Insb Films
Authors: Zuhoski S. P. , Killeen K. P. , Biefeld R. M.
Published: March 2011

Films of InSb were deposited on GaAs <100> substrates at room temperature by excimer laser photolysis at 193 or 248 m of a mixture of trimethylindium (TMIn) and trimethylantimony (TMSb) in a hydrogen carrier medium. These films were compared to thermally grown MOCVD InSb films by optical microscopy and x-ray analysis and found to be stoichiometric polycrystalline, InSb. In situ UV absorption spectroscopy has been used for the first time on an MOCVD system to monitor and control the partial pressures of the metalorganic reactants during deposition. This latter diagnostic was found to be critically important since parasitic reactions cause depletion of TMIn during transport from the source bubbler to the growth chamber.
Excimer Laser-Assisted Movpe of Cdte on Gaas (100): Crystal Growth and Mechanisms
Authors: Zinck J.J. , Brewer P.D. , Jensen J.E. , Olson G.L. , Tutt L.W.
Published: March 2011

Excimer laser-assisted MOVPE has been used to deposit thin films of CdTe (111) on GaAs (100) substrates. Auger spectroscopy indicates that the films are stoichiometric and that carbon and oxygen contamination are below the levels of detectability. Good crystalline quality of the layers is confirmed by x-ray diffractometry. Growth rates up to 2 /μm/hr have been recorded in real time using time-resolved reflectivity. The CdTe growth rate is found to have a linear dependence on reactant partial pressure and laser average power, but was independent of substrate temperature in the range of 150° C to 300* C. Laser-induced fluorescence spectroscopy has been used to determine that photolysis of diethyltellurium at 248 nm is a one photon process which produces ground state Te atoms. The flux of reactive species to the substrate surface has been probed by mass spectrometry. Evidence for the generation of monoethyltelluride, either by recombination or direct photolysis, is presented.
Growth of Highly Oriented CdsXSe1.X Thin Films By Uv Laser Evaporation Deposition
Authors: Kwok H.S. , Mattocks P. , Shaw D.T. , Shi L. , Wang X.W. , Witanachchi S. , Ying Q.Y. , Zheng J.P.
Published: March 2011

CdSxSe1−x thin films have been grown by uv laser-evaporation deposition in a clean vacuum environment. The films have their c-axis perpendicular to the surface, and are optically smooth and homogeneous. These high quality films should be useful in nonlinear integrated optics applications.
Epitaxial Growth of Thin Ge Films on [001] Gaas by Laser Photochemical Vapor Deposition from GeH4
Authors: Tavitian V. , Kiely C. J. , Eden J. G.
Published: March 2011

Epitaxial Ge films have been grown on [001] GaAs for substrate temperatures (Ts) as low as 285°C by photodissociating GeH4 at 193 nm in parallel geometry. For a laser fluence of ~15 mJ - cm-2, the film growth rate varies from 0.6 to ~5 nm - min-1, depending upon Ts and gas pressure. Plan and cross-sectional TEM studies of the Ge/GaAs bicrystal demonstrate that the 400–700 A thick Ge films are single crystal and epitaxial with the substrate. The present limitation on epitaxial film thickness appears to be imposed by reduced adatom mobility at the temperatures investigated.
Low Temperature Oxide and Nitride Film Depositions by Simultaneous Use of Ionized Cluster Beam Source and Microwave Ion Source
Authors: Takagi Toshinori , Takaoka Gikan H. , Ishikawa Junzo
Published: March 2011

Aluminum oxide (A12O3), nitride(A1N) and silicon nitride(SiN) films were prepared at a low substrate temperature of 100°C. Film resistivity was higher than 5x1013 Ω-cm and the breakdown voltage was greater than 3x10° V/cm. The films deposited on sapphire and silicon substrates were very flat, and were chemically and thermally stable. The A1-O, A1-N and Si-N bonds could be formed effectively by using both ionized clusters and reactive gas ions, and transparent and good quality films were obtained. Through these results, the simultaneous use of an ionized cluster beam (ICB) system and a microwave ion source was found to have a high potential for preparing oxide and nitride films at a low substrate temperature.
Synthesis of Epitaxial Silicon Carbide Films by Laser CVD
Authors: Nakamatsu Hirohide , Hirata Kazuhiko , Kawai Shichio
Published: March 2011

ArF exciraer laser CVD was performed to give epitaxial SiC films on the sapphire or (α-A12O3 (0001) substrate. The rate of film growth was limited by the diffusion of the supplied gases. Small amounts of the gas supply failed to produce the SiC deposition and etched the substrate. The UV light irradiation of the substrate was necessary for the photo-excitation to grow the adherent epitaxial films. Filtered UV light from a D2 lamp revealed that the light with the wavelength shorter than about 310nm was effective for the epitaxial growth. It was found to be essential to excite intermediate products or by-products in the absorbed layer on the substrate. The epitaxial SiC films on the αA12O3 gave blue photoluminescence which may be ascribed to the superstructure of 3C-type SiC crystals.
Control of Solid-Excitation-Based Photochemical Dry Etching of Semiconductors by Ion-Bombardment-Induced Damage
Authors: Ashby C.I.H. , Myers D. R.
Published: March 2011

Carrier-driven photochemcial dry etching of semiconductors can be selectively suppressed by ion-implantation-induced defects. The magnitude of this suppression depends on the semiconductor impurity doping concentration, the ion fluence, and the photo-excitation wavelength.
Laser Direct Writing of Aluminum
Authors: Cacouris T. , Scelsi G. , Scarmozzino R. , Osgood R.M. , Krchnavek R.R.
Published: March 2011

We report, for the first time, laser direct writing of high conductivity aluminum interconnects from dimethylaluminum hydride (DMALH). These lines were deposited from a metallorganic gas with a focused deep-UV laser beam and were directly connected to aluminum test structures. Electrical measurements and Auger electron spectroscopy were used to characterize the laser deposited films.
Elastic-Recoil-Detection Measurement of Instabilities in Proton-Exchanged Lithium Niobate
Authors: Arnold G. W. , Carnera A. , Mazzi G. , Mazzoldi P.
Published: March 2011

The H and Li profiles in proton-exchanged (PE) LiNbO3, have been measured using elastic recoil detection (ERD). Profiles were determined as a function of crystal orientation, time after PE, annealing temperature, MgO-doping, and added Li-benzoate to the benzoic acid proton source. The proton-exchange process produces Hx Li1−x NbO3 structures where x stabilizes near values of x=0.5 or x=0.7-0.75 depending on specific conditions. The ERD measurements represent the first direct and simultaneous measurements of H- and Li-concentrations in PE LiNbO3 and their variation with process parameters.
Low Resistivity Contact Formation for Lsi Interconnection With Short-Pulse-Laser Induced Mo Cvd
Authors: Uesugi F. , Morishige Y. , Shinzawa T. , Kishida S. , Hirata M. , Yamada H. , Matsumoto K.
Published: March 2011

The contact characteristics between Al interconnections in LSI's and direct written Mo lines has been substantially improved by adopting, for the first time, short-pulse-laser induced Mo CVD. The linewidth stability upon Al interconnections has also been improved. Transient, localized heating with short laser pulses effectively overcomes the heat dissipation through Al interconnections which degraded contact characteristics and prevented fine drawing near the Al interconnection. This new scheme can appreciably widen the applicable device field of direct writing circuit restructuring.
Direct Writing of Carbon Interconnections
Authors: Lyons Alan M. , Wilkins C. W. , Mendenhall F. T.
Published: March 2011

The in situ formation of conductive carbon lines in polymeric substrates was demonstrated by “writing” with CO2 and Nd:YAG lasers. The formation of conductive carbon lines on polymer substrates proceeds through a series of steps including; absorption of light, initiation of decomposition reactions, and thermal propagation of the pyrolysis. The effect of material composition, power density, energy density, and wavelength on the electrical resistance and morphology of the carbon lines was investigated.
Above a critical laser energy density (= 400 J/cm2) sufficient light is absorbed by the substrate such that initiation of the pyrolysis reactions occurs. The decomposed polymer strongly absorbs the incident radiation and the thermal propagation of the reactions forms shiny, conductive, carbon lines. The dimensions of these lines are dependent on the energy density impinging on the polymer and are independent of the wavelengths investigated. If too high a power density is employed (∼ 104 Watts/cm2), an ablated track is formed down the center of the carbon line. This results in the relative insensitivity of the linear resistance with increasing power above 104 Watts/cm2.
Periodic Structure Formation During Laser Direct-Writing of Palladium Acetate Films: An Optically Regulated Mechanism
Authors: Baufay L. , Gross M. E.
Published: March 2011

Laser direct-writing of micron-size metallic features from Pd acetate film precursors is achieved using a scanned cw Ar+ laser. Marked periodic structure is observed in these features under a wide range of exposure conditions. A model based on laser reflectivity and transmittance measurements has been developed to describe the formation of the periodic structure. The model takes into account a complex relationship between optical absorption, laser-induced heating and reaction rate. The decomposition of Pd acetate to metal is endothermic and, therefore, this system differs fundamentally from the “explosive” crystallisation of amorphous semiconductors.
Study of the Carrier Concentration Effect on Si Enhanced AlGaAs/GaAs Superlattice Mixing
Authors: Mei Ping , Venkatesan T. , Schwarz S. A. , Stoffel N. G. , Harbison J. P. , Florez L. A.
Published: March 2011

We have investigated the carrier concentration effect on AlGaAs/GaAs superlattice mixing enhanced by Si doping. The Al0.01Ga0.99As/GaAs superlattice sample with various Si-doping concentrations was grown by molecular beam epitaxy (MBE). Secondary ion mass spectrometry (SIMS) and carrier concentration profiling were used to characterize the Al diffusion and the free-carrier concentration profiles. The Al diffusion coefficients at 800 C show a high power dependence on the free carrier concentration which is not consistent with a Ga vacancy diffusion mechanism. A possible explanation can be provided by a mechanism based on a Si pair diffusion model.
Atmospheric Pressure OMCVD Growth of GaAs Using Triethylarsenic and Alkylgallium Organometallic Precursors
Authors: Speckman Donna M. , Wendt Jerry P.
Published: March 2011

Triethylarsenic was successfully used as a substitute for arsine in the atmospheric pressure OMCVD growth of GaAs epilayers. N-type GaAs films were produced at V/III ratios of 14–45 and growth temperatures of 560–590°C. The highest quality epilayers obtained were grown at temperatures of 560–570°C and V/Ill ratios of 23–27, with the best films exhibiting net carrier concentrations and 77K mobilities of ∼1015 cm−3 and ∼14,000cm2/V-s, respectively. All of the films grown using Et3As were found to be contaminated with carbon, which appears to result from an inherent decomposition mechanism of the Et3As reagent.
Band-Edge Luminescence of MOCVD GaAs Grown Directly on Silicon
Authors: Lamont M. G. , Harris T. D. , Sauer R. , Lum R. M. , Klingert J. K.
Published: March 2011

We report a detailed study using photoluminescence and photoluminescence excitation of MOCVD GaAs grown directly on Si substrates. Temperature variation and selective excitation allow reliable assignment of spectral features. This assignment permits measurements of strain and strain uniformity, identification of impurities, and assessment of general materials quality. In 2–5μm thick layers similar spectra are observed with little variation from substrate character. Most samples show one of the two split valence band features plus defect recombination, always including carbon. Strain uniformity varies widely and correlates with substrate thickness. The range of spectra observed from a variety of samples, and guidelines for interpretation of nonresonantly excited spectra will be discussed.
Modifications in the Course of Reaction Between Co and GaAs Due To The Presence of a Ge Film
Authors: Genut M. , Eizenberg M.
Published: March 2011

Modifications in the course of reaction between Co thin films and single crystal GaAs substrate due to the addition of a Ge film either on top or below the metal layer have been studied. The microstructure and phase formation for the systems: Co/GaAs, Co/Ge/GaAs, and Ge/Co/GaAs have been studied by Auger electron spectroscopy, transmission electron microscopy and X-ray diffraction.
Ultrathin Single Crystal CoSi2 Layers on Si(111) and Si(100)
Authors: Tung R. T. , Batstone J. L. , Yalisove S. M.
Published: March 2011

The growth of ultrathin epitaxial CoSi2 layers on Si by molecular beam epitaxy has been studied. This paper briefly outlines recent progress in the growth on Si(111) substrates. New results on the growth of epitaxial CoSi2 on Si(100) are also presented.
The Electronic Properties of Silicon-Silicide Epitaxial Interfaces
Authors: Ossicini Stefano , Bisi O.
Published: March 2011

The selfconsistent electronic properties of the epitaxial Si(111)-NiSi2 interface are computed for the experimentally observed type-A and type-B growth orientations. The densities of states projected on the various sites provide a detailed analysis of the siliconsilicide interface electronic states. The measured Schottky barrier heights may be interpreted by assuming that deviations from epitaxy must be taken into account.
In-Situ Surface Cleaning of Ge(111) and Si(100) for Epitaxial Growth of Ge AT 300°C Using Remote Plasma Enhanced Chemical Vapor Deposition
Authors: Hattangady S. V. , Rudder R. A. , Fountain G. G. , Vitkavage D. J. , Markunas R. J.
Published: March 2011

We have demonstrated low temperature (300°C) Ge epitaxy on Ge(111) and on Si(100) substrates. Critical to this epitaxy has been the use of wet chemistry to produce controlled, thin oxides on the substrates prior to loading into the reactor and an in-situ 300°C hydrogen plasma treatment to remove those oxides from the semiconductor surfaces. Reflection high energy electron diffraction shows the plasma treatments to be effective in producing clean, well-ordered surfaces. This represents a new approach for in-situ cleaning of Ge(111) and Si(100) surfaces.
High Resolution Transmission Electron Microscopy Investigation of the Defect Structure in CdMnTe Layers Grown on GaAs by MOCVD
Authors: Mazur J. H. , Grodzinski P. , Nouhi A. , Stirn R. J.
Published: March 2011

Electron diffraction and high resolution electron microscopy were used for analysis of Cd1−xMnxTe films grown on (100)2°[011] GaAs substrates by metal organic chemical vapor deposition (MOCVD) at 420°C (x=O.3) and 450°C (x=0.5). It has been found that these two conditions produce dramatically different microstructures. Two orientation relationships of the epilayers with respect to the substrate were observed. It is suggested that this phenomenon may be related to GaAs substrate surface morphology.
In-Situ Rapid Thermal Annealing of Heterostructures Grown by Molecular Beam Epitaxy
Authors: Cerullo M. , Phillips Julia M. , Anzlowar M. , Pfeiffer L. , Batstone J. L. , Galiano M.
Published: March 2011

A new in-situ rapid thermal annealing (RTA) apparatus which can be used to anneal entire wafers in an ultra high vacuum environment has been designed to be used in conjunction with the epitaxial growth of heterostructures. Drastic improvement in the crystallinity of CaF2/Si(100) can be achieved with RTA, and our results suggest that RTA can be used as an on-line processing technique for novel epitaxial structures.
Strain Adjustment in Si/Sige Superlattices
Authors: Kasper E. , Herzog H.-J. , Jorke H. , Abstreiter G.
Published: March 2011

The performance of future microelectronic circuits will be strongly enhanced by the monolithic integration of superlattice devices with convenventional integrated circuits ontop of a silicon substrate. With this material concept the mismatch between the superlattice materials and the silicon substrate has to be accommodated. SiGe/Si is a model system for the study of mismatch effects because of similar chemistry and well pronounced strain effects.

Growth of SiGe/Si strained layer superlattices (SLS) by molecular beam epitaxy is reported. Adjustment of strain within the superlattice influences strongly the stability and band ordering of the SLS. SiGe/Si superlattices with strain symmetrization exhibit good thermodynamic stability and band ordering of type II. The concept of strain symmetrization by a thin homogeneous buffer layer is explained. Design rules for a virtual substrate consisting of the actual substrate with the thin buffer layer on it are given.
Strained Layer Semiconductor Films: Structure and Stability
Authors: Feldman L. C. , Bevk J. , Davidson B. A. , Gossmann H.-J. , Ourmazd A. , Pearsall T. P. , Zinke-Allmang M.
Published: March 2011

Strained layer epitaxy is a process for the formation of new materials with a strain and composition modulation in the one to one hundred monolayer range. Two aspects of strained epitaxial growth are discussed in this paper. We first consider the clustering process, a basic limitation in strained layer epitaxy. A second experiment examines the strain in few monolayer epitaxial films of Ge embedded in Si(100). We show that the strain in these monolayer films is comparable to that expected from bulk elastic constants and discuss the new properties of these films.
Surface Reconstruction of MBE-Grown GeXSi1−x on Si(111)
Authors: Huang C. F. , Karunasiri R. P. G. , Park J. S. , Wang K. L. , Kang T. W.
Published: March 2011

Surface reconstruction during the molecular beam epitaxy (MBE) growth of GexSi1−x ( x = 0.2 - 1.0 ) film on Si(111) was studied using reflection high energy electron diffraction (RHEED). A series of reconstruction pattern transitions was observed due to the formation of strain layer and its relaxation. The critical thickness obtained using the thickness of the GexSil-x film at the transition of the reconstruction pattern agrees well with the previously reported values. The strain dependence of RHEED patterns for GexSi1−x film was substantiated by Raman scattering.
Study of Initial Stages of Heteroepitaxy Using Graded Thickness Samples
Authors: Biegelsen D. K. , Ponce F. A. , Krusor B. S. , Tramontana J. C. , Yingling R. D.
Published: March 2011

In this paper we introduce the technique of graded thickness sample deposition to study the heteroepitaxial growth mechanisms of GaAs on Si. We can observe the continuous evolution from the initial clean surface, through nucleation, growth and coalescence of the deposited material.
Hetroepitaxy of GaAs by MBE on High Temperature Hydrogen Annealed Nominally (100) Oriented Silicon
Authors: Humphreys T. P. , das K. , Posthill J. B. , Parikh N. , Tarn J. , EL-Masry N. , Bedair S. M. , Chu W. K. , Wortman J. J.
Published: March 2011

High-quality GaAs epitaxial layers have been grown by molecular beam epitaxy on nominally (100) oriented silicon substrates annealed in a hydrogen-ambient at 1250 ? C. Growth procedure involves an in-situ thermal annealing step after the initial deposition of a thin GaAs buffer layer. Rutherford backscattering and channeling of 2.1 MeV He+ ions, interference optical and transmission electron microscopy have been used to characterize these layers. Comparative studies indicate that the epitaxial layers grown on hydrogen-ambient annealed substrates have a superior surface morphology and a lower interface disorder than those on chemically cleaned silicon (100) substrates. Microtwins, dislocations and antiphase domain boundaries are the predominant defects observed in these layers. A lower incidence of microtwins were observed in the hydrogen annealed substrates.
Effect of Atomic Structure at the Epitaxial CaF2 /Si(111) Interface on Electrical Properties
Authors: Batstone J.L. , Phillips Julia M. , Hunke E.C.
Published: March 2011

High resolution electron microscopy has been used to determine the atomic structure at the epitaxial CaF2 /Si(111) interface before and after a rapid thermal anneal. Direct Ca-Si bonding at the interface, with 8-fold coordinated Ca atoms is observed in as-grown layers. Fluorine is preferentially removed from the interface during a rapid thermal anneal leaving 5-fold coordinated Ca atoms. A dramatic improvement in the electrical properties of the interface is observed after annealing. The measured interface state density is reduced from ≳1013 cm−2 to ≲1011cm−2. This has been correlated with the removal of F from the interface. No evidence for direct F-Si bonding is observed.
MBE Growth and Properties of Fe Films on Lattice-Matched InxGa1−xAs Films
Authors: Farrow R. F. C. , Parkin S. S. P. , Speriosu V. S. , Wilts C. H. , Beyers R. B. , Pitner P. , Woodall J. M. , Wright S. L. , Kirchner P. D. , Pettit G. D.
Published: March 2011

.We report the growth and magnetic properties of epitaxial Fe films, prepared by MBE on films of GaAs and In0.2Ga0.8As, on GaAs (100) substrates. We find that the magnetic properties of the Fe films, which are in the thickness range 300-900Å have virtually no dependence on the nature of the buffer film between the GaAs substrate and the Fe film. In terms of FMR linewidth, 4πMs and anisotropy, the Fe films are of the highest quality yet reported. Values of exchange constant and surface anisotropies were derived from an analysis of spinwaves observed in the thickest films.
X-ray topography and EBIC studies of misfit dislocations in strained layer structures
Authors: Hamaguchi N. , Humphreys T. P. , Parker C. A. , Bedair S. M. , Jiang B-L. , Radzimski Z. J. , Rozgonyi G. A.
Published: March 2011

X-ray topography(XRT) and EBIC have been used to study the generation of misfit dislocations in strained layer structures. Two structures studied were GaAs1−yPy(y=0.15) film and SLS consisting of InxGa1−xAs(x=0.08) and GaAs1−y Py(y=0.16) layers. XRT and EBIC techniques gave consistent results for the behavior of dislocations. The value of the critical thickness for generation of misfit dislocations in the former was found to be few times larger than that in the latter. EBIC image showed that a SLS lattice matched to the substrate is effective in reducing defects originating from the substrate.
Stability Diagrams for Epitaxial Strained Layers
Authors: Tsao J. Y. , Dodson B. W. , Picraux S. T.
Published: March 2011

For bulk materials, plastic deformation mechanisms and rates depend in a complex way on resolved shear stress and temperature, but can be succinctly described using the deformation mechanism maps pioneered by Ashby and Frost [1]. In this paper, we describe the use of such maps to demarcate the various stability and metastability regimes of single and multilayered strained epitaxial structures, and to interpret experimental work in the SiGe system.
In-Situ and High-Resolution Tem Observation of Interfacial Reactions in Metal-Silicon Multilayers
Authors: Holloway Karen , Do Khiem BA , Sinclair Robert
Published: March 2011

Titanium-silicon and molybdenum-silicon multilayers have been investigated in cross-section using a high resolution TEM with a point-to-point resolution of .22 nm. This resolution has allowed us to confirm the amorphous nature both of the intermixed layers which form at the metal-silicon interfaces on sputter deposition, and of the Ti-Si reaction product which forms at temperatures below which crystalline silicides nucleate.

The bulk studies are complemented by in-situ annealing experiments in the high-resolution microscope. Phase reactions in the multilayers can be followed in real time, allowing direct observation of the formation of the amorphous alloy, the appearance of rows of Kirkendall voids, and the crystallization and growth of silicide phases.
The Effect of Ion Implantation on the Interdiffusion in Si/Ge Amorphous Artificial Multilayers
Authors: Park B. , Spaepen F. , Poate J. M. , Priolo F. , Jacobson D. C. , Pai C. S. , White A. E. , Short K. T.
Published: March 2011

Amorphous Si/Ge artificial multilayers have been implanted with Si and B at liquid nitrogen temperature, and partially ion mixed with Ar at different temperatures. In all cases, the square of the mixing length was found to be proportional to the dose. Annealing of Si-implanted samples showed that after relaxation the diffusivity appeared unaffected by the implantation process. Annealing of the B-implanted samples showed an enhancement of the diffusivity at the higher dose. The diffusive component of the square of the mixing length in the Ar-ion mixed samples has an Arrhenius-type temperature dependence, with an activation enthalpy of 0.22 eV.