bluuebunny/crossref_metadata_2025_split huggingface dataset:
Ferroelectric Thin Films by Metal Organic Chemical Vapour Deposition
Authors: Ainger F.W. , Brierley C.J. , Hudson M.D. , Trundle C. , Whatmore R.W. 
Published: March 2011

ABSTRACTThere is a growing interest in thin films of ferroelectric oxides because of their electronic and optoelectronic applications. Various growth processes are being explored, but here, we review progress with chemical vapour deposition in a purpose built low pressure reactor. The two ferroelectric perovskites selected for our initial studies were lead titanate and lead scandium tantalate which have necessitated the synthesis of proprietary precursors. These compounds are based on metal alkoxides and β-diketonates, and are suitably modified to exhibit the required volatility and necessary thermal and hydrolytic stabilities.Deposition has been studied over the temperature range 400–800°C and, in general, amorphous films result which can be converted by subsequent annealing to crystalline perovskites. However, the inclusion of hydroxyl group compounds (H2O or alcohols) in the vapour train catalyses the crystallisation process and enhances the growth rates at temperatures in excess of 600°C. In order to deposit the perovskite phase, it is important to maintain the gas phase composition throughout the growth. Deposition rates of up to 10μm/hour can be achieved, but the best thin films, in terms of density and morphology, are formed at lower deposition rates. The crystallite size of the deposit may vary from 0.1μm up to 2μm, depending on temperature. The choice of precursors, gas compositions and the growth conditions will be discussed in conjunction with the electrical and structural properties of the layers grown.
Effect of Thermal Processing Conditions on Ferroelectric PZT Thin Films
Authors: Kwok Chi K. , Desu Seshu B. , Kammerdiner Lee 
Published: March 2011

ABSTRACTFerroelectric and transparent lead–zirconate–titanate thin films were fabricated by rf sputtering. The substrates used were Pt–coated single crystal silicon. The deposition temperatures were relatively low (≅ 200°C). Annealing at high temperatures yielded first pyrochlore type and finally perovskite with good switching characteristics. The phase structure, microstructure, surface composition, and properties were measured as a function annealing time and temperature. In general, the Pb concentration on the surface decreased with increasing annealing temperature or time, whereas Zr concentration increased. It was observed that the grain size of perovskite PZT did not show any significant changes with increasing either anneal temperature or time.
Characterization of Ferroelectric Thin Film PLZT(9/65/35) on R-Plane Sapphire
Authors: Krishnakumar S. , Esener S.C. , Fan C. , Ozguz V.H. , Title M.A. , Cozzolino C. , Lee S.H. 
Published: March 2011

ABSTRACTThe deposition of ferroelectric PLZT on r-plane sapphire using R-F Triode Magnetron Sputtering is reported. R-plane (1102) sapphire is chosen, in spite of its large lattice mismatch to PLZT, because of its capability of integrating MOS silicon circuits with PLZT modulators. Perovskite PLZT films with the desired composition (9/65/35) are obtained using co-deposition techniques around 500°C and post deposition annealing at 650°C. The deposited films exhibit good optical and electro-optical properties. The room temperature dielectric constant of the films was 1800 at 10 Khz. The refractive index of the films was in the range 2.2–2.5. The films showed a quadratic E-O effect with R=0.6×10−16 m2/V2. The films are promising for smart Spatial Light Modulators (SLM) applications.
Substrate Temperature Effects on Properties of Silicon Nitride Films Deposited by Ion Beam Assisted Deposition
Authors: Donovan E. P. , Carosella C. A. , Grabowski K. S. , Coleman W. D. 
Published: March 2011

AbstractSilicon nitride films (Si1−x,.Nx) have been deposited on silicon by simultaneous evaporation of silicon and bombardment of nitrogen ions. Films approximately 1 μm thick were deposited in an ambient nitrogen pressure of 50 μTorr. The substrate temperature (TSUB) ranged from nominally room temperature to 950° C for films with X between 0 and 0.6. Nitrogen atom fraction, X, was measured with Rutherford backscattering spectrometry (RBS). Refractive index was measured with near-IR reflection spectroscopy. Differences in film structure were measured by FT1R on the Si-N bond bending absorption mode, and by x-ray diffraction (XRD). X was found to depend upon the incident flux ratio of energetic nitrogen atoms to vapor silicon, and upon TSUB. Refractive index depends upon X and TSUB. XRD found evidence of the presence of amorphous structure, poly-crystalline silicon and (101) oriented β-Si3N4 depending on X and TSUB. The Si-N absorption signal increases with X and shows some structure at high TSUB.
Reactive Ion Etching of Copper with SiCl4 and CCl2F2
Authors: Howard B. J. , Wolterman S. K. , Yoo W. J. , Gittleman B. , SteinbrÜchel CH. 
Published: March 2011

AbstractCopper may become an alternative to aluminum as an interconnect material in future multilevel metallization schemes if it is possible to pattern Cu by dry etching in a manufacturable process. Here we report results on the reactive ion etching of Cu in SiCl4 /Ar, SiCl4/N2, and CCl2F2/Ar plasmas. Etch rates have been investigated as a function of various plasma parameters, such as gas composition, pressure, etc., and substrate temperature. We have obtained etch rates as high as 850 Å /min with SiCl4/N2 and a substrate temperature of ∼ 200 ° C. Also, it appears feasible to pattern Cu anisotropically using either polyimide or amorphous carbon as a high-temperature etch mask.
Optimization of Reactive Ion Etching Parameters Via Material Characterization
Authors: Cole M. W. , Cooper C. B. , Dutta M. , Wrenn C. S. , Saliman S. , Lee H. S. , Fotiadis L. , Saunders M-L. , Chang W. H. 
Published: March 2011

AbstractThis study evaluates variations in SiCl4 reactive ion etching (RIE) process parameters in order to optimize the fabrication of lateral quantum well arrays (QWA) used in III–V semiconductor laser and detector designs. Since fabrication involves MBE regrowth on SiCl4 etched surfaces, material quality of both the etched surface and GaAs regrowth are evaluated. The variation of RIE parameters involved power levels, DC bias and etch times (10 Watts, -30V, 8 min.; 25 Watts, -100V, 5 min.; 95 Watts,-340V, 2 min.) while material removal was held constant (400nm). Evaluation of the etched surfaces revealed that the lattice damage depth exceeded lOOnm for all power levels. The extent of disorder beneath the etched surface was less for the low power long etch time. Etching at higher power levels for shorter time periods resulted in smoother surfaces and enhanced electrical characteristics, which in turn yielded a higher quality GaAs regrowth region. For the RIE parameters examined in this study, the variation in defect densities seemed to have a lesser effect on device performance as compared to the extreme differences in surface morphologies. Thus, for the parameters evaluated in this work, we suggest that QWA fabrication is optimized via SiClif RIE at the high power level for a short time period.
Fabrication of a-Si:H/a-Al1−xOx Superlattice by Excimer Laser MOCVD and its Properties
Authors: Uwasawa K. , Ishihara F. , Wada J. , Matsumoto S. 
Published: March 2011

Abstracta-Si:H/a-A11−xOx superlattice structures have been fabricated by ArF excimer laser MOCVD. Periodic variation of composed elements in multilayers with quite uniform layer thickness was clearly shown by SIMS analysis. Optical band gap was increased with the decrease of the well layer thickness, indicating the quantum size effect. With the advantage of the inherent digital process, very sharp interface was obtained, which was confirmed by both XPS and cross sectional TEM analyses.
Silicon Homoepitaxy at 300°C Using ArF Excimer Laser Photolysis of Disilane
Authors: Fowler B. , Lian T. , Bullock D. , Banerjee S. 
Published: March 2011

AbstractPhotolysis of Si2H6 by an ArF excimer laser has been used to deposit Si homoepitaxial layers at temperatures as low as 300°C. The chemical vapor deposition process at growth rates from 0.5-4 Å/minute is performed in an ultra-high vacuum chamber which, along with an ex situ HF dip and a novel in situ hydrogen clean using laser excitation, results in minimization of oxygen and carbon contamination which inhibits Si epitaxy. The growth involves photolytic decomposition of Si2H6 and the generation and adsorption of SiH2 precursors on the hydrogenated Si surface, which is the rate limiting step. Growth rates are observed to vary proportionally with laser power. Very low defect density films in terms of stacking faults and dislocation loops (less than 105 cm−2), and excellent crystallinity have been deposited as confirmed by Schimmel etching and Nomarski microscopy, transmission electron microscopy, electron diffraction and in situ reflection high energy electron diffraction.
Effect of Laser Heating on Compositions of Films Deposited from the Metal Hexacarbonyls
Authors: Singmaster K. A. , Houle F. A. 
Published: March 2011

AbstractA systematic study of the composition of metal films thermally deposited by laser heating (cw 514 nm) of the group VI hexacarbonyls is described. The films are found to contain significantly lower levels of carbon and oxygen than photochemically deposited films, and are spatially inhomogeneous. Estimates of temperature to determine the extent of laser heating permit the kinetics of this process to be compared to ∞ desorption from single crystal surfaces.
Characterization of BaTiO3 Thin Films Deposited by Pulsed-Laser Ablation
Authors: Scarfone Christopher , Grant Norton M. , Barry Carter C. , Li Jian , Mayer James W. 
Published: March 2011

AbstractThin films of barium titanate (BaTiOs) have been deposited by pulsed-laser ablation onto (001)-oriented MgO substrates. The films were epitactic as evidenced by both x-ray diffraction and ion-channeling techniques. The film surface appeared smooth and contained a low density of particulates. This latter feature is believed to be due to the formation of target pellets having a very high density.
Collision Cascades in Zr3Al
Authors: Howe L. M. , Rainville M. H. 
Published: March 2011

AbstractZr3Al is an ordered f.c.c. alloy of the L12 type, which under various irradiation conditions can be disordered and then eventually amorphized. In the present transmission-electron-microscopy (TEM) investigation, the nature of the damaged regions formed in individual collision cascades was investigated using low fluence (< 1 × 1011 ions cm−2) bombardments at 290 K with 15 − 120 keV 63Cu ions.Imaging under dynamical conditions with the fundamental 111, 200, 220 and 113 reflections revealed damaged regions (5.1 - 8.1 nm average diameter) that exhibited black-white strain contrast features. These damaged regions have essentially a spherically symmetrical strain field and probably are three-dimensional clusters of point defects. Imaging with 110 superlattice reflections revealed additional damaged regions (2.4 - 3.7 nm average diameter), which appeared as black spots, that represent disordered regions in the ordered lattice. For both the strain-contrast regions and the disordered regions, as the incident ion energy increased, the number of damaged regions produced per incident ion increased and the fraction of the theoretical collision cascade volume occupied by these regions decreased.
Modeling of Damage Enhanced Diffusion of Implanted Boron in Silicon
Authors: Lo V. C. , Wong S. P. , Lam Y. W. 
Published: March 2011

AbstractModeling of the damage enhanced diffusion (DED) behaviors of implanted boron in silicon of Powell’s experiment [1] has been performed. In his experiment, Powell showed that the diffusion of implanted boron in silicon was dependent on implantation dosage as well as on the annealing conditions. For low dose boron implantation, the extent of boron diffusion after 15 second RTP is less than that of furnace annealing at 900°C for 30 minutes. But the reverse is true for the high dose case, and a two-step annealing leads to least and minimal diffusion. In this work, implantation induced excess self-interstitials which generate mobile boron atoms at the intersititial sites are considered the dominant point defect species responsible for the DED. Both the local relaxation and diffusion of these excess self-interstitials are considered. The features of the DED reported by Powell are successfully reproduced and explained.
The Use of 2-Mev He+ Microbeams for Ion-Beam Mixing of Bi-Layer Systems
Authors: Davis John B , Benenson R.E. 
Published: March 2011

AbstractWe have observed ion-beam mixing in three bi-layer targets, Sb/Si, Cu/Si and Cu/Al, using 2-MeV He+ beams of 4 – 9 urn width. Detailed investigation of Cu/Al revealed that 1) the depth of the mixed layer exhibits a linear dependence on dose, equivalent to 80 A for every 1018 He+ ions/cm2; 2) there is evidence of lateral diffusion of the mixed atoms away from the line of application of the beam; and 3) the sputtering coefficient for 2.0-MeV He+ on Cu is 0.07 sputtered atoms per ion.
Temperature Dependence of DC Conductivity in Ion-Beam-Irradiated Glassy Carbon
Authors: McCulloch Dougal , Prawer Steven 
Published: March 2011

AbstractThe electrical conductivity of ion beam irradiated Glassy Carbon has been investigated in the temperature range 100 to 300 K. Ion species used were C+ and N+ with doses between 1014 and 1018 ions/cm2. Ion beam irradiation was found to lower the conductivity of Glassy Carbon by up to six orders of magnitude. The temperature dependence of the conductivity in ion beam modified Glassy Carbon has been measured. The functional dependence was found to remain largely unchanged by ion irradiation despite the large overall decrease in the conductivity. The results are interpreted in terms of a model which includes a variable range hopping and strongly scattering metallic components.
Reactive Ion Etching of III-V Semiconductors Using Hydrogenated Chlorofluorocarbon Mixtures
Authors: Pearton S. J. , Hobson W. S. , Chakrabarti U. K. , Derkits G. E. , Perley A. P. 
Published: March 2011

AbstractThere are two basic gas chemistries used for dry etching of III-V semiconductors. The most common discharges contain chlorine, but these generally give rise to somewhat rough surface morphologies for In-containing compounds. More recently methane/hydrogen mixtures have been demonstrated to give low rate, smooth etching of In-based materials. In this work we describe the use of gas mixtures containing both CH and CI species. The hydrochlorofluorocarbons CHCl2F and CHCIF2 with O2 or H2 addition were used to reactively ion etch GaAs, InP, AlGaAs, GaSb, InGaAs and AlInAs as a function of etch time, plasma power density, pressure and gas composition. At moderate power densities (0.56 W · cm−2) the etch rates are in the range 125 Å · min−1 (AlInAs) to 1000 A · min−1 (GaAs). All of the materials exhibit smooth surface morphologies over a wide range of RIE parameters and there is no significant lattice disorder introduced for low power RIE as evidenced by PL and diode I-V measurements. Thin (≤40 Å) surface residue layers of CI (3–9 at. %) and F(≤3 at. %) for all materials except AlInAs are present after dry etching, but these can be removed by simple solvent cleaning.
Influence of Temperature and Electron Energy on Solid-Phase Epitaxy of Implanted Si Induced at Low Temperature by Electron Irradiation in the Electron Microscope
Authors: Lulli G. , Merli P. G. , Garulli A. , Antisari M. Vittori 
Published: March 2011

AbstractElectron beam induced solid-phase epitaxy has been obtained on cross sections of implanted Si layers, by in-situ irradiation in the electron microscope, with electrons of energies of 200 and 300 keV, in the temperature range −170≤T≤20°C. The rate of the induced transformation is shown to depend very weakly on temperature (activation energies of the order of 10−2 eV ), and to be basically related to the nuclear energy loss of electrons, even if the ratio of the rates observed for irradiation at 300 and 200 keV slightly increases with T, thus deviating from the exact theoretical ratio between displacement cross sections. These facts are likely to be related to a temperature dependence of the rate of defect production and to the effect of a ionization-enhanced diffusion mechanism, rather than to a thermal mechanism of defect migration. Furthermore, the linear dependence of epitaxial rate from the dose rate leads, in the framework of a simple diffusion model, to infer that mutual interaction (recombination, clustering) between defects must be negligible. These features are discussed and compared with the results and models of ion-beam induced crystallization, which occurs in the range 200≤T≤400°C. It is concluded that different assumptions on defect kinetics must be made in the different temperature ranges where electron and ion-beam induced epitaxy occur, in order to reproduce their dependence on the main irradiation parameters.
Measured Lattice Damage and Optical Index Change in KNbo3
Authors: Irmscher R. , Fluck D. , Buchal CH. , Stritzker B. , GÜnter P. 
Published: March 2011

AbstractWe have used 2-MeV and 200-KeV He implantation into KNbO3 and LiNbO3 single crystals to generate a damaged layer of reduced optical index. MeV implantation enables the formation of optical waveguides of several µm thickness, which have been analyzed by dark and bright line spectroscopy in order to determine the refractive index profiles. In addition, 200-keV implants have been used to model the end-of-range-damage, which was measured by RBS/Channeling. KNbO3 and LiNbO3 show a distinctly different sensitivity of the radiation damage.
Crystallisation and Diffusion in <001> Oriented Sapphire Amorphised by Zinc Ion Implantation
Authors: Bunn L. A. , Sood D. K. 
Published: March 2011

AbstractHigh dose zinc implantation (1×1016 to 6×1016 ions/cm2) into c-axis sapphire at 770K produces amorphous surface layers. Post-implantation annealing at temperatures at and above 800°C show that the modes of recrystallisation are strongly dependant on ion dose. At low doses formation of crystallites of α and γ phase Al2O3 is seen, with no evidence of any planar epitaxial growth at the original crystalline-amorphous interface. The zinc is seen to diffuse isotropically within the crystallised layer and becomes partially substitutional within the crystallites. At high doses, however, the formation of crystallites is inhibited, with the layer remaining amorphous. A more rapid diffusion of zinc is seen in the amorphous Al2O3, with some of the zinc being lost at the surface.
Low Fragmentation Laser Desorption of Thermally Labile Molecules
Authors: Atkinson Ian M. , Shorter Jeffrey A. , Karaiste Timo , Keene F. Richard , Steinfeld Jeffrey I. , Knight Alan E.W. 
Published: March 2011

AbstractThermally labile involatile inorganic complexes and biomolecules have been laser desorbed from silver doped emulsions without significant fragmentation. The silver doped emulsions are saturated with the molecule of interest and then mounted in the source chamber of a skimmed molecular beam apparatus. A pulsed frequency doubled Nd:YAG laser is used to desorb the molecules. The desorbed molecules are entrained in a pulsed supersonic expansion of argon, and are thereby cooled rotationally and vibrationally. A pulsed tunable dye laser is used to ionize the desorbed molecules (either resonantly or non-resonantly) between the acceleration grids of a Wiley-McLaren configuration time-of-flight mass spectrometer. Mass-resolved detection of the ions created from the desorbed species reveals that the desorption process causes almost no fragmentation for all the species studied (various aromatic amino acids and inorganic coordination compounds such as the [Ru(2,2’bipyridyl)3] moiety). While other techniques are successful for introducing relatively involatile materials into mass spectrometers, they often lead to substantial fragmentation of the molecular species of interest. Laser desorption combined with laser ionization can minimize fragmentation during both the vaporization process and the ionization step. Furthermore, a specific merit of our sample handling technique involving silver doped emulsions is that the number density of desorbed species is found to remain sufficiently stable on a shot-to-shot basis so as to permit the recording of wavelength scanned resonance enhanced multiphoton ionization spectra. The combination of laser desorption with resonance enhanced multiphoton ionization spectroscopy has thus provided for the first time a means of recording electronic spectra for a range of vibrationally and rotationally cooled involatile materials.
Maskless Laser Etching of Alumina and Ceramic Substrates
Authors: Khan Jamal 
Published: March 2011

AbstractMaskless patterning of alumina (A12O3) films of various thicknesses and ceramic (TiC-Al2O3) substrate material was accomplished by using pulsed excimer and Nd:YAG laser systems. Etched structure size was defined through the computer software which also controls the workpiece position and laser operating parameters. Etch profile, materials removal rate and surface roughness was found to be dependent on laser emission wavelength, fluence, pulse rate and relative scan speed. Smoother etching was obtained with the excimer lasers. The etch characteristics are compared with those of the polymeric and metallic materials. Various potential applications of this laser based etching process in microelectronic and micromagnetic device fabrication are identified.
Laser Rapid Sintering of Metallo-Organic Derived Oxide Films
Authors: Louh Rong-Fuh , Buchanan Relva C. 
Published: March 2011

AbstractOxide films of ZrO2, Y2O3, yttria stabilized zirconia (YSZ), and high Tc superconducting YBa2Cu3O7-x and Bi-Sr-Ca-Cu-O films were produced by spin coating metallo-organic precursors onto Si, ZrO2 and MgO single crystal substrates. Densification of these oxide films, after pyrolysis of organic constituents, was achieved by scanning a Nd:YAG laser beam across the film surface. Surface morphology, microstructures, spatial grain size distribution, compositional variations, defects and physical properties of laser sintered films were characterized using SEM, EDS, TEM, SIMS, XRD and 4-point electrical resistivity probe. Laser processing parameters, deposited film thickness and organic burn-off showed strong influences on the film densification behavior. This paper focuses on pursuing optimum conditions for obtaining dense, uniform sintered patterns in oxide films and on understanding the film-substrate interaction and dynamics of nucleation and growth via the laser rapid sintering process.