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Journal of Vacuum Science & Technology A: Vacuum, Surfaces, and Films

Issue 3 • Date May 1996

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Displaying Results 1 - 25 of 233
  • Surface‐immobilized plasma proteins and platelet activation in the non‐self‐ recognition of foreign materials

    Page(s): 669 - 673
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    The immobilization of plasma proteins and activation of platelets were studied at surfaces of five different materials, i.e., titanium, gold, quartz, methylized quartz, and mercaptopropanediol monolayers on gold. Immobilization of plasma proteins was measured with ellipsometry using specific antibodies for detection of individual proteins adsorbed after exposure of materials to heparin plasma for 1 min. Activation of platelets was measured with immunofluorescence of platelet surface antigens and F‐actin after exposure of materials to whole blood from 15 s to 4 min. The results show different profiles of surface‐immobilized plasma proteins and differences between the material surfaces in the number of adhering cells, the degree of aggregation of the cells, the content of F‐actin, and the number of extracellular microparticles adhering to the surface. Blood–titanium contact resulted in a characteristic, early and marked formation of F‐actin in platelets. © 1996 American Vacuum Society View full abstract»

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  • In situ high‐resolution atomic force microscope imaging of biological surfaces

    Page(s): 674 - 678
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    In situ high‐resolution atomic force microscope imaging of biological surfaces was performed on cells with relatively rigid surfaces (e.g., bacteria). The surface of Lactobacillus helveticus (a rod‐shaped bacterium) was investigated before and after exposure to LiCl, a denaturant. Image details were stable both at variant force loads and under different scan directions. From images of the oblique lattice structure (i.e., S layer of L. helveticus), it was estimated that the lateral resolution of the images was up to 2 nm. This resolution can be explained by assuming that there is an apex with a curvature of radius of ∼10 nm near the end of the tip. Modelling of this geometry indicates that such a tip configuration is particularly suitable for in situ high‐resolution imaging of relatively soft objects covered by a rigid shell (membrane). © 1996 American Vacuum Society View full abstract»

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  • Non‐self‐recognition of metals in blood and peritoneal cavity

    Page(s): 679 - 684
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    To explore the hypothesis that protein adsorption followed by platelet adhesion and activation has an effect on the nature of the subsequent inflammatory response, we studied the cell–implant reactions to Ti and Au in blood and the peritoneal cavity. The metals were exposed to blood (in vitro) and peritoneal fluid (in vivo). In blood the adhesion and activation of platelets and leucocytes were studied by fluorescence microscopy using specific FITC‐labeled antibodies or acridine orange. Intraperitoneal leucocyte adhesion was studied by scanning electron microscopy, transmission microscopy, or by staining with acridine orange. The metallic surfaces were exposed to both blood and peritoneal fluid for times varying from 15 s to 4 h. The results show (a) that a significantly larger number of platelets followed by a correspondingly large number of leucocytes initially adhere to Ti rather than to Au, (b) that the rate of the inflammatory response as manifested by the appearance of leucocytes is more rapid in the peritoneal cavity than in blood, and (c) that cells attach directly to the Au surfaces while being separated by an amorphous layer on the Ti surfaces. Thus an interesting nexus exists between the composition of the adsorbed protein layer, platelet adsorption, and activation and the rate and nature of leucocyte recruitment and interaction with implanted materials. © 1996 American Vacuum Society View full abstract»

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  • Optical properties of cobalt oxide films deposited by spray pyrolysis

    Page(s): 685 - 692
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    The optical constants of Co3O4 films were determined by analyzing variable angle of incidence spectroscopic ellipsometry data and normal incidence transmittance data, between 3500 and 17 000 Å. Absorption was taken to be nonzero for the soda–lime–silica float glass substrate. The absorption of the soda–lime–silica float glass was fitted by an ensemble of four Gaussian oscillators over the entire measured spectral range. Surface roughness of the film was measured with atomic force microscopy and included in the optical model. The films were deposited by spray pyrolysis of cobalt acetylacetonate onto heated soda–lime–silica float glass and fused silica substrates. Fused silica was used to observe film absorption without the effect of substrate absorption. The oxide film phase was identified with thin‐film x‐ray diffraction analysis. Simultaneous fits of ellipsometry and transmittance data from coated samples were computed to obtain the film thickness, optical constants, and the amplitudes of the four Gaussian oscillators representing the glass substrate absorption. This analysis was done by treating the optical constants at each wavelength as simple fitting parameters or as variables with a Kramers–Kronig consistent parametric model. Spectra for the most accurate optical constants of Co3O4 films deposited by spray pyrolysis onto both substrates are presented. © 1996 American Vacuum Society View full abstract»

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  • Determination of chemistry and microstructure in SiOx (0.1≪x≪0.8) films by x‐ray photoelectron spectroscopy

    Page(s): 693 - 698
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    The stoichiometry of a series of low pressure chemical vapor deposition deposited SiOx films was determined using x‐ray photoelectron spectroscopy (XPS) by two different methods. The first, more traditional, method involved applying relative sensitivity factors to the integrated O 1s and Si 2p peaks, taking into consideration differences in photoemission probabilities of oxidized and elemental silicon. In the second method the Si 2p spectra were curve fit into five peaks corresponding to Si0+SiH (99.4 eV), Si1+ (100.3 eV), Si2+ (101.2 eV), Si3+ (102.0 eV), and Si4+ (103.0 eV). The five valence states of silicon corresponding to tetrahedrally coordinated silicon bonded to 0, 1, 2, 3, and 4 oxygen atoms. The relative areas of the peaks were combined with the known oxygen coordination numbers to yield stoichiometries. Rutherford backscattering and hydrogen forward scattering were done to verify the XPS quantification and to measure the hydrogen concentration of the films, respectively. The fraction of elemental silicon present as a function of oxygen concentration was compared with the fraction predicted by a random bonding model of silicon and oxygen atoms. The experimental fraction of Si0+SiH measured by XPS was greater than the fraction predicted by the random bonding model consistent with distinct regions (or possibly crystallites) of elemental silicon in the oxide matrix. Also, it was established that 3 kV argon sputtering does not preferentially sputter oxygen from either SiO2 or SiOx films contrary to previous reports. © 1996 American Vacuum Society View full abstract»

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  • A study of Si compounds by Zr Lα photoelectron spectroscopy

    Page(s): 699 - 703
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    Zirconium Lα radiation has been utilized to investigate the chemical bonding in silicon compounds by x‐ray photoelectron spectroscopy. The compounds studied in the present investigation are SiO2, SiO, SiC, Si3N4, and silicon‐oxynitrides. The spectra in the Si 1s and KLL Auger regions were recorded for these compounds and compared with the elemental spectra. In order to estimate the change in chemical environment of Si in these compounds, the Auger parameter was determined in each case as the difference between the binding energies for the 1s and the KLL peaks. The trend in the value of the Auger parameter is correlated with the degree of atomic relaxation due to the increasing neutralization of charge around the Si cations in these compounds. A good agreement was found between the change in the Auger parameter and the bond ionicity calculated for the Si cation in these compounds. Using this plot, the bond ionicities were determined for the oxynitrides. A model is also developed to estimate these ionicities from the concentrations of oxygen and nitrogen present in these compounds. The values of the ionicities obtained by these two different methods give a satisfactory agreement. We have shown that the plot between the change in the Auger parameter and the bond ionicity could be used to estimate the bond ionicities. © 1996 American Vacuum Society View full abstract»

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  • Thin metal films deposited at low temperature for optoelectronic device application

    Page(s): 704 - 708
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    Thin metal layers play an important role in the development of electronic devices. Thin metal films deposited at low temperature (LT=77 K) have shown some unique properties which enhance device performance. The microstructure properties of thin metal films formed at room temperature (RT=300 K) and LT were investigated in this work. An insulating substrate was used for Au, Ag, and Al metal deposition. The surface morphology and microstructure of the metal films was studied by transmission electron spectroscopy (TEM) and atomic force microscopy (AFM). The resistance of the thin films was measured in situ as a function of film thickness and temperature. It was found that all LT thin films become electrically continuous at a much lower thickness than the RT films. Electrical measurements determined that the LT films demonstrated several orders of lower resistance compared to RT film at very thin (less than 100 Å) thickness, which could lead to the potential applications of these films on electronic and optoelectronic devices. It is observed by both TEM and AFM that the LT films showed much lower density of grain boundaries than the RT samples at the same thickness. This is consistent with the resistance measurement results. © 1996 American Vacuum Society View full abstract»

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  • Charge issues in high oxygen gas ratio tetraethylorthosilicate plasma enhanced chemical vapor deposition films

    Page(s): 709 - 713
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    The effect of multilayered silicon dioxide films on reflective charge, Nss, and flatband voltage, Vfb, was investigated using plasma enhanced chemical vapor deposition. Parameters investigated included the thickness and type of oxide film layers, as well as dopant type. Deposition of a high oxygen gas ratio film [4:1, oxygen:tetraethylorthosilicate (TEOS)] as the first layer of a multilayer film resulted in a statistically lower Nss and a smaller shift in flatband voltage, Vfb, than films deposited with lower oxygen gas ratios (1:1, oxygen:TEOS). Multilayer films were deposited to a thickness of 18 kÅ using a high oxygen gas ratio as the initial layer. These films exhibited Nss and Vfb values of 1.28×1011 cm-2 and -11.5 V, respectively. In contrast, those films with a lower oxygen gas ratio initial layer exhibited statistically higher Nss and Vfb values of 1.70×1011 cm-2 and -15.4 V, respectively. Film compositional changes in subsequent layers did not display any statistically significant change in either Nss or Vfb. The deposition of 4:1 gas ratio films occurs at a slower rate than the 1:1 gas ratio films. The use of 4:1 gas ratio films as the initial layer of a multilayer film allows for lower Nss and smaller shifts in Vfb without significantly affecting throughput. © 1996 American Vacuum Society View full abstract»

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  • Experimental and theoretical study of vibrations of a cantilevered beam using a ZnO piezoelectric sensor

    Page(s): 714 - 719
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    Piezoelectric sensors can measure vibrations of solid structures very accurately. A model of a cantilevered beam, with a ZnO film on one side is presented. Both viscous and internal damping are considered. The output of the sensor is modeled and matched with experimental results by adjusting the damping parameters. A theoretical formulation for damage is introduced. Experimental results for a damaged beam confirm the shift in frequencies to lower values. The model is used to identify the extent of the damage. © 1996 American Vacuum Society View full abstract»

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  • Reflective coatings for large‐area solar concentrators

    Page(s): 720 - 726
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    Reflective/protective coatings were applied to pre‐formed 2.5‐m‐long solar concentrator panels by the magnetron sputtering process. Low‐cost manufacturing processes such as hydrostatic forming of aluminum solar concentrator panels are needed to keep the costs of domestic power generation low. Without treatment, the specular reflectance of the aluminum panels was less than 20%. As expected, silver (Ag) and aluminum (Al) coatings applied directly over the untreated panels did not significantly increase specular reflectance. To provide a specular base surface, approximately 100‐μm‐thick urethane layers were applied to the panels before deposition of the reflective coating. This smoothing layer filled in scratches and defects. Reflective Ag and Al layers, with protective overcoats of Al2O3 and Si3N4, were deposited onto the urethane‐coated panels by reactive magnetron sputtering with ion assist in Pacific Northwest National Laboratory’s 3 m coating chamber. The specular reflectance of the panels increased to an average of 92% at visible wavelengths, very near the reflectance of Al coatings on highly polished glass. Panels with Ag metal layers displayed similar increases. The optical performance uniformity of the coating was better than ±5%. The measured primary concentration ratio of the panels was 800:1, which far exceeded the design ratio of 500:1. The total concentration ratio was 2400:1. The coatings passed MIL‐spec environmental and durability tests. Field testing of the concentrator dishes and coatings is continuing, and test results will be reported. © 1996 American Vacuum Society View full abstract»

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  • Scaleup of a nitrogen glow‐discharge process for silver–poly(ethylene terephthalate) adhesion

    Page(s): 727 - 732
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    In situ studies of plasma‐treated poly(ethylene terephthalate) [PET] followed by metallization suggested a viable process for treating and silver coating PET support to manufacture suitable silver‐coated base material. Following this work and some proof‐of‐principle demonstrations on a pilot scale, a successful process was delivered at the manufacturing scale. The scaleup process consisted of running a multifactor experiment on a pilot machine, installing the necessary production equipment on a production coater, and carrying out a smaller multifactor experiment on the production machine to aid in selection of manufacturing conditions. Key to the success of this scaleup process was the ability to measure silver–PET adhesion in a sufficiently quantitative and practical manner. For this purpose a salt bath adhesion test was developed. By using this test as an experimental response, robust operating conditions were found. Furthermore, the test provided a means to troubleshoot, track the process, and establish performance/cost trade‐offs. The adhesion test and the pilot and production experiments are discussed. © 1996 American Vacuum Society View full abstract»

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  • High rate vacuum deposition of polymer electrolytes

    Page(s): 733 - 738
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    Two new, high rate, vacuum processes have been developed for the deposition of polymer electrolyte layers on wide web substrates. One method involves the vacuum extrusion of monomer salt solutions followed by e‐beam or ultraviolet (UV) curing. The second method involves the vacuum flash evaporation of the monomer salt solution followed by e‐beam or UV curing. Each method is compatible with simultaneous, in‐line, deposition by conventional processes like sputtering or evaporation in a wide web system. Optically clear polymer electrolyte layers may be deposited at line speeds in excess of 100 meters per minute with these new techniques. Ionic conductivity measurements will be presented for vacuum deposited, evaporated and extruded, polymer electrolyte layers. Films were deposited with thicknesses ranging from 2 to 50 μm. Application of these methods to ongoing electrochromic and battery work at the Pacific Northwest Laboratory will be discussed. © 1996 American Vacuum Society View full abstract»

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  • Development of a multilayer thin‐film solar control windshield

    Page(s): 739 - 746
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    The trend in automotive glazing design has been towards more steeply sloped windshields with larger glass areas, resulting in greater transmission of solar radiation. Driver comfort, air conditioning load, and fabric deterioration are some of the challenges manufacturers of automotive glazing face because of these new designs. Ultraviolet and solar infrared radiation must be effectively reduced while visible light transmission must be maintained above 70% (the legal limit). The windshield surface, which receives up to 60% of the solar irradiation incident upon the vehicle glazing, is traditionally tinted, resulting in absorption and reradiation. The most effective means of reducing the solar heat load, however, is by using a multilayer coating which reflects the solar energy. The coating consists of two layers of silver sandwiched between antireflective dielectric metal oxide layers. The coating is applied to the inner surface of the outer glass light of the laminated windshield using the dc magnetron sputtering process. For the coating process to be both cost effective in manufacturing, and suitable for a variety of complex shaped windshields, the glass is first coated flat, and subsequently bent and laminated. The coating process can then be integrated into the windshield manufacturing process without limiting throughput. This multilayer coating, specifically developed to be bent on soda–lime–silicate glass, remains stable and uniform for complex, and small radius of curvature bends. The development of this coating in the laboratory, transfer into production, and integration into the windshield manufacturing process is described. © 1996 American Vacuum Society View full abstract»

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  • Reactive‐sputter deposition and structure of RuO2 films on sapphire and strontium titanate

    Page(s): 747 - 752
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    Metallic films of RuO2 were deposited by reactive‐sputtering deposition on single crystal substrates of Al2O3 (0001) and SrTiO3 (100) at room temperature and 450 °C. Measurement of the characteristic hysteresis loop revealed that the target’s transition from a metal to a metal oxide surface occurred at a very high O2/Ar ratio (88%) under our experimental conditions. The hysteretical behavior of the transition was evaluated experimentally and was modeled. Resonance‐enhanced Rutherford backscattering spectrometry established that the films deposited at 450 °C had an oxygen to ruthenium ratio of 1.97, while a slightly higher value of 2.08 was observed for the films grown at room temperature. The latter films were amorphous, whereas those grown at 450 °C exhibited a highly oriented polycrystalline microstructure. On SrTiO3 (100), the RuO2 (100) plane is parallel to the substrate surface, but no in‐plane orientation was found. The same face, RuO2 (100), was also parallel to the surface of Al2O3 (0001), and the [001] direction of individual grains of RuO2 aligned with the three 〈1¯010〉 directions of the substrate to produce a threefold mosaic microstructure. © 1996 American Vacuum Society View full abstract»

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  • Response characteristics of lead phthalocyanine gas sensor: Effect of operating temperature and postdeposition annealing

    Page(s): 753 - 756
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    Effects of operating temperature and postdeposition annealing, as well as gas concentration and flow rate, on the response characteristics of the lead phthalocyanine sensor are investigated in this work. A simple model based on the gas adsorption/desorption kinetics was developed; it predicts that the reciprocal of the response time is proportional to both NO2 concentration and gas flow rate, but decreases with operating temperature. From the temperature dependence of the reciprocal of response time, the activation energy of the adsorption process, Ea, and that of the desorption process, Ed, can be calculated. It is also found that heat treatment of the lead phthalocyanine film in air at 250 °C for 3 h will reduce the activation energies, and lead to faster sensor response. © 1996 American Vacuum Society View full abstract»

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  • Estimation and verification of the optical properties of indium tin oxide based on the energy band diagram

    Page(s): 757 - 761
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    Indium tin oxide (ITO) is a transparent conducting material used in optoelectronic applications. In order to optimize the optical properties of ITO, it is necessary to determine these properties as a function of the free carrier concentration (i.e., doping In2O3 with Sn). Based on an ab initio Hartree–Fock calculation of the energy band diagram of indium oxide and indium oxide doped with tin, an empirical relationship of the electron effective mass as a function of the ideal free carrier concentration is established. The importance of the varying electron effective mass in the prediction of the complex dielectric function, the refractive index, extinction coefficient, and finally the optical transmission based on Drude’s theory is shown here by comparing the estimated results with measured and published results. The agreement between estimated values and measured or published experimental results is very good. © 1996 American Vacuum Society View full abstract»

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  • Temperature‐dependent Raman scattering in PT and PMN‐PT thin films

    Page(s): 762 - 767
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    Raman spectroscopy was used to investigate PbTiO3 (PT) and 0.7Pb(Mg1/3 Nb2/3)O3‐0.3PbTiO3 (PMN‐PT) thin films prepared by the sol–gel technique and deposited on platinum‐coated silicon, and Al2O3. The PT spectra reveal that the films are polycrystalline in nature and the frequencies of most of the modes are decreased as compared to those in single crystal or powder material. This result is due to grain under stress, which is caused by nonequilibrium defects. Temperature dependence (290–60 K) of the Raman half‐width bands in PT/Al2O3 is discussed in terms of anharmonic processes involving three phonons, however, the main contribution to line broadening appears to be due to presence of defects. In the case of PMN‐PT films the temperature dependence study indicates strong disorder in the system, predominantly, in the B sites of the ABO3 perovskite structure. The bands are, therefore, interpreted as due to a breakdown in the phonon momentum conservation within the Brillouin zone. Micro‐Raman measurements at different film positions indicate that PT/Al2O3, and PMN‐PT/Pt/Si films are homogeneous, while PT/Pt/Si films show different microstructure in the middle and edge positions. Scanning electron microscopy, Fourier transform infrared spectroscopy, and x‐ray diffraction techniques have been used for the structural characterization. © 1996 American Vacuum Society View full abstract»

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  • Formation of an in situ diffusion barrier while diffusing aluminum through boron‐enriched nickel

    Page(s): 768 - 771
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    A coating process is described in which a boron‐doped nickel layer is first deposited onto a substrate and is then overcoated with aluminum. This duplex coating is annealed such that a nickel aluminide coating is formed on top of a boron‐based diffusion barrier. During a low temperature anneal, the boron, which had been evenly distributed throughout the Ni layer, becomes concentrated in a remnant Ni layer which is located between the substrate and a NiAl overlayer. During a high temperature anneal on Ti‐alloy substrates, Ti borides are formed. This study reveals two stages in which diffusion is inhibited. First, diffusion is inhibited by the boron‐enriched nickel layer. Second, diffusion is arrested by a titanium diboride diffusion barrier. Results of electron and ion spectroscopies are used to illustrate the nature and effectiveness of the diffusion barrier when applied to various Ti‐alloy substrates. In this application, it is shown that the diffusion of Ti, V, and Mn, into the NiAl layer is inhibited. Anticipated benefits of this barrier, when employed with oxidation protection coatings, are discussed. © 1996 American Vacuum Society View full abstract»

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  • Phase development in sputter deposited titanium dioxide

    Page(s): 772 - 776
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    We report the formation of highly oriented rutile titanium dioxide films. Films of a primarily amorphous nature were grown on fused silica by rf reactive sputter deposition using a Ti target and rare gas (Ne or Ar)‐O2 discharges. Post‐deposition annealing was done at 350–1150 °C in air for 60 minute intervals, followed by an air cool. The phase mixture of the as‐deposited films, determined by x‐ray diffraction, was of two types: (I) amorphous + rutile + anatase, or (II) amorphous + rutile. All phases were highly oriented with (110) rutile planes and (101) anatase planes parallel to the substrate. Upon annealing, the amorphous component of films containing no anatase transformed entirely to rutile, even at temperatures where it is possible to form anatase, ≪800 °C, indicating that anatase requires ‘‘seeds’’ to form. The results of this study clearly demonstrate that the crystal structure of the as‐deposited film determines the development of the rutile phase with post‐deposition annealing. © 1996 American Vacuum Society View full abstract»

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  • Nitrogen‐ion irradiation during the deposition of C1-xNx thin films by ion beam sputtering technique

    Page(s): 777 - 780
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    The morphology of the carbon nitride (C1-xNx) thin films deposited by the reactive ion beam sputter deposition technique has been studied. A pure graphite target has been sputtered using nitrogen ions. Some of the deposited films have been irradiated with the primary nitrogen ion beam during the deposition. The films were prepared at room temperature on the crystalline Si substrates. The IR absorption spectrum of the C1-xNx film irradiated with lower energy (0.6 keV) ions has an absorption band that peaked at 1550 cm-1, which has been attributed to the graphitic sp2‐bonded carbon (G band) in the study of Raman spectroscopy, while the nonirradiated film which was deposited with a 0.6 keV beam has shown neither a G band nor a D band corresponding to the disordered sp3‐bonded carbon in the IR spectra. On the other hand, the films irradiated with a higher energy (1.0 keV) ion beam have shown a very broad ‘‘D‐band’’ IR spectrum in the IR range between 1000 and 1700 cm-1. The x‐ray photoelectron spectroscopy spectra indicate that all films contain nearly equal quantities of the C≡N triple and C=N conjugated double bonds, while the IR absorption peaks attributed to the C≡N stretching mode are larger in the ion‐irradiated samples than in the nonirradiated ones. These results suggest that sputtering by and/or irradiation of a higher energy ion beam contribute to form terminations of the diamondlike carbon network, which contains pyridinelike structures, in the form of cyano‐radicals since the absorption peak due to the C≡N stretching mode is enhanced when cyano‐radicals bond with a conjugated system in the neighboring sites. © 1996 American Vacuum Society   View full abstract»

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  • Surface processing by gas cluster ion beams at the atomic (molecular) level

    Page(s): 781 - 785
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    Gas cluster ion beam techniques have been developed for atomic and molecular level surface modification processing. Shallow implantation, high yield sputtering, surface smoothing, and low damage surface cleaning have been demonstrated experimentally. This article reports recent results concerning surface treatments that are distinctly different from those produced by conventional monomer ion irradiation. Possible applications of gas cluster ion beam processing to new areas of surface modifications are suggested. © 1996 American Vacuum Society View full abstract»

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  • Numerical ellipsometry: Real‐time solutions using mapping onto the complex index plane

    Page(s): 786 - 790
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    While in situ ellipsometry measurements can be made on growing films, real‐time solutions for thickness and optical properties remain challenging. Numerical techniques are necessary because for practical material systems, the equations are not generally invertible. In the absorbing film on a known substrate problem, the typical real number unknowns (film n1, k1, and d) outnumber the real parameters (Ψ and Δ) obtained in a single measurement. Although it is known that two intersecting sets of n1, k1, and d values are established from two measurements, in the past these sets have not been well understood. The work here is a thorough investigation of such curves and explores all theoretically possible intersections for metals depositing onto an oxide substrate. Mathematical and material considerations identify the solution intersection in a few milliseconds for real‐time monitoring and control. © 1996 American Vacuum Society View full abstract»

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  • High transmittance–low resistivity ZnO:Ga films by laser ablation

    Page(s): 791 - 794
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    High transmittance, low resistivity, and c‐axis highly oriented ZnO:Ga thin films on glass were obtained by laser ablation at different deposition temperatures. The surface morphology, crystalline structure, and optical and electrical properties were found to depend directly on substrate temperature. From optical and electrical analyses we observed that the optical transmittance, carrier concentration, and optical energy gap of the ZnO:Ga transparent conductive oxides increased when the deposition temperature is raised from 150 to 300 °C. Films grown on 300 °C substrates showed a low resistivity value of 3.6×10-4 Ω cm, a carrier concentration of 8.7×1020 cm-3, a band gap of 3.81 eV, and a visible transmission of 85%. These films were deposited with an excimer (KrF) laser beam of λ=248 nm operated under optimized conditions of 2.7 mJ/cm2 energy density and 30 Hz repetition rate. © 1996 American Vacuum Society View full abstract»

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  • Zirconium silicate thin films for antireflection coatings

    Page(s): 795 - 799
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    Antireflection coatings are used to enhance the performance of a wide variety of optical devices. Laser and nonlinear optical devices are among the most demanding for antireflection coating applications, requiring both excellent optical properties and good durability. In this article, we report on the optical properties of zirconium silicate based thin films and their application as antireflection coatings for a number of components used in laser applications. These films have been demonstrated to be easily and reproducibly prepared, to have readily tailored indices of refraction, and to withstand the high optical intensities found in device applications. Films with indices of refraction in the range of 1.6–1.9 have been prepared using rf planar magnetron sputtering, allowing optimized antireflection coatings to be deposited on a variety of materials, including GaP, GaAs, and AlGaAs. © 1996 American Vacuum Society View full abstract»

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  • Sputter deposited piezoelectric fiber coatings for acousto‐optic modulators

    Page(s): 800 - 805
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    All‐fiber optical phase modulators were fabricated by coating standard telecommunication optical fibers with thin films of piezoelectric ZnO. Piezoelectric optical fiber coatings of PbZrxTi1-xO3(PZT) were also produced, and the actuation capability necessary for making optical fiber modulators is demonstrated. Both the ZnO and the PZT fiber coatings were deposited by reactive direct current magnetron sputtering of metal targets. The geometry of the sputtering system, fiber rotation, and reactive sputtering processes that result in sufficiently high deposition rates for deposition of axially symmetric coatings between 0.5 and 7 μm thick were studied. Two types of piezoelectric fiber optic modulator structures, Cr/Au/ZnO/Cr/Au and Ti/Pt/PZT/Au, are currently being investigated. Results on crystalline phase formation, microstructure, and piezoelectric and optical behavior of the coated optical fiber devices are presented. Impedance and phase angle measurements are used to demonstrate how device geometry affects the resonance response of ZnO coated devices. Interferometric measurements have shown that the ZnO‐based modulators can produce optical phase shifts as high as 0.70 rad when the modulator is driven at the 196.5 MHz fiber radial resonance. © 1996 American Vacuum Society View full abstract»

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Aims & Scope

The Journal of Vacuum Science and Technology A is devoted to reports of original research, review articles, and Critical Review articles.

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Editor
G. Lucovsky
North Carolina State University