23 Matching Results

Search Results

Advanced search parameters have been applied.

Tribological performance of diamond and diamondlike carbon films at elevated temperatures

Description: In this study, we investigated the tribological performance of diamond and diamondlike carbon (DLC) films as a function of ambient temperature. Both films were deposited on silicon carbide (SiC) by microwave plasma chemical vapor deposition and ion-beam deposition processes. Tribological tests were performed on a reciprocating wear machine in open air (20 to 30% relative humidity) and under a 10-N load using SiC pins. For the test conditions explored, the steady- state friction coefficients of test pairs without a diamond or DLC film were 0.7 to 0.9 and the average wear rates of pins were 10{sup {minus}5} to 10{sup {minus}7} mm{sup 3}/N.m, depending on ambient temperature. DLC films reduced the steady-state friction coefficients of test pairs by factors of 3 to 5 and the wear rates of pins by two to three orders of magnitude. Low friction coefficients were also obtained with the diamond films, but wear rates of the counterface pins were high due to the very abrasive nature of these films. The wear of SiC disks coated with either diamond or DLC films was virtually unmeasurable while the wear of uncoated disks was substantial. Test results showed that the DLC films could afford low friction up to about 300{degrees}C. At higher temperatures, the DLC films became graphitized and were removed from the surface. The diamond films could withstand much higher temperatures, but their tribological behavior degraded. Raman spectroscopy and scanning electron microscopy were used to elucidate the friction and wear mechanisms of both films at high temperatures.
Date: September 1, 1995
Creator: Erdemir, A. & Fenske, G.R.
Partner: UNT Libraries Government Documents Department

Incorporation of iron cations into epitaxial sapphire thin films by co-evaporation and subsequent thermal annealing

Description: Iron-doped sapphire thin films have been successfully epitaxially grown onto sapphire single crystal substrates by electron beam deposition and subsequent thermal annealing. Amorphous Al{sub 2}O{sub 3} thin films, about 280--390 nm thick, cation doped with iron have been deposited on [0001] oriented sapphire substrates. Iron doping with cation concentrations (a ratio of Fe content to total cation content) up to 5 at % can be incorporated into the octahedral sites of Al-cation sublattice during the epitaxial regrowth process at 1,000--1,400 C, as determined by Rutherford Backscattering Spectrometry and ion channeling measurements. Cross-sectional Transmission Electron Microscopy shows the presence of two distinct regions in the annealed films. One exhibits the epitaxial relationship with the sapphire substrate and the second region has amorphous type of contrast. External optical transmittance measurements in the ultra violet and visible light range have exhibited the absorption associated with Fe{sup 3+}. This study has demonstrated a simple method of incorporating dopants into single crystal sapphire, which has potential in the fabrications of thin film planar optical waveguides.
Date: May 1, 1994
Creator: Yu, N.; Kung, H.; Nastasi, M. & Li, D.
Partner: UNT Libraries Government Documents Department

Formation of artificially-layered superconducting materials by pulsed-laser deposition

Description: Artificially-layered structures, consisting of (Sr,Ba,Ca)CuO{sub 2} layers in the tetragonal, {open_quotes}infinite layer{close_quotes} crystal structure, have been grown by pulsed-laser deposition. Superlattice chemical modulation is observed for structures with SrCuO{sub 2} and (Sr,Ca)CuO{sub 2} layers as thin as a single unit cell ({approximately}3.4 {Angstrom}). In addition, novel thin-film superconductors were formed by using the constraint of epitaxy to stabilize SrCuO{sub 2}/BaCuO{sub 2} superlattices in the infinite layer structure. Using this approach, two new structural families, Ba{sub 2}Sr{sub n-1}Cu{sub n+1} O{sub 2n+2+{gamma}} and Ba{sub 4}Sr{sub n-1}Cu{sub n+3}O{sub 2n+6+{gamma}}, have been synthesized which superconduct at temperatures as high as 70 K. These results represent not only the synthesis of new structural families of superconductors, but also demonstrate that pulsed-laser deposition and epitaxial stabilization can be effectively used to engineer artificially-layered thin-film materials.
Date: September 1, 1994
Creator: Norton, D.P.; Chakoumakos, B.C. & Budai, J.D.
Partner: UNT Libraries Government Documents Department

Formation and properties of novel artificially-layered cuprate superconductors using pulsed-laser deposition

Description: Pulsed-laser deposition and epitaxial stabilization have been effectively used to engineer artificially-layered thin-film materials. Novel cuprate compounds have been synthesized using the constraint of epitaxy to stabilize (Ca,Sr)CuO{sub 2}/(Ba,Ca,Sr)CuO{sub 2} superconducting superlattices in the infinite layer structure. Superlattice chemical modulation can be observed from the x-ray diffraction patterns for structures with SrCuO{sub 2} and (Ca, Sr)CuO{sub 2} layers as thin as a single unit cell ({approximately}3. 4 {angstrom}). X-ray diffraction intensity oscillations, due to the finite thickness of the film, indicate that (Ca,Sr)CuO{sub 2} films grown by pulsed-laser deposition are extremely flat with a thickness variation of only {approximately}20 {angstrom} over a length scale of several thousand angstroms. This enables the unit-cell control of (Ca, Sr)CuO{sub 2} film growth in an oxygen pressure regime in which in situ surface analysis using electron diffraction is not possible. With the incorporation of BaCuO{sub 2} layers, superlattice structures have been synthesized which superconduct at temperatures as high as 70 K. Dc transport measurements indicate that (Ca, Sr)CuO{sub 2}/BaCuO{sub 2} superlattices are two dimensional superconductors with the superconducting transition primarily associated with the BaCuO{sub 2} layers. Superconductivity is observed only for structures with BaCuO{sub 2} layers at least two unit cells thick with {Tc} decreasing as the (Ca,Sr)CuO{sub 2} layer thickness increases. Normalized resistance in the superconducting region collapse to the Ginzburg-Landau Coulomb gas universal resistance curve consistent with the two-dimensional vortex fluctuation model.
Date: March 1, 1996
Creator: Norton, D.P.; Chakoumakos, B.C. & Budai, J.D.
Partner: UNT Libraries Government Documents Department

Deposition and surface treatment with intense pulsed ion beams

Description: Intense pulsed ion beams (500 keV, 30 kA, 0.5 {mu}s) are being investigated for materials processing. Demonstrated and potential applications include film deposition, glazing and joining, alloying and mixing, cleaning and polishing, corrosion improvement, polymer surface treatments, and nanophase powder synthesis. Initial experiments at Los Alamos have emphasized thin-film formation by depositing beam ablated target material on substrates. We have deposited films with complex stoichiometry such as YBa{sub 2}Cu{sub 3}O{sub 7-x}, and formed diamond-like-carbon films. Instantaneous deposition rates of 1 mm/sec have been achieved because of the short ion range (typically 1{mu}m), excellent target coupling, and the inherently high energy of these beams. Currently the beams are produced in single shot uncomplicated diodes with good electrical efficiency. High-voltage modulator technology and diodes capable of repetitive firing, needed for commercial application, are being developed.
Date: February 8, 1995
Creator: Olson, J.C.; Davis, H.A.; Rej, D.J.; Waganaar, W.J.; Stinnett, R.W. & McIntyre, D.C.
Partner: UNT Libraries Government Documents Department

Influence of microstructure on laser damage threshold of IBS coatings

Description: Ion-beam sputtering (IBS) coatings were developed for the laser gyro industry to meet significantly different requirements than those of fusion lasers. Laser gyro mirrors are small (< 25 mm) and require low losses (< 30 ppm typical) and high stability with long exposures to low power laser energy. In contrast, fusion laser optics are large (< 1 meter), have significantly reduced loss requirements (< 5,000 ppm) and high damage thresholds (> 26 J/cm{sup 2} at 1,064 nm with 3-ns pulses). As part of the National Ignition Facility (NIF) coating development effort, IBS coatings are being studied to explore the possible benefits of this technology to NIF optics. As an initial step to achieving the NIF size and damage threshold requirements, the coating process is being scaled to uniformly coat a 20 x 40 cm{sup 2} area with reduced spectral, reflected wavefront, and laser damage threshold requirements. Here, multilayer coatings deposited by ion-beam sputtering with amorphous layers were found to have lower damage thresholds at 1,064 nm than similar coatings with crystalline layers. Interestingly, at higher fluences the damage was less severe for the amorphous coatings. The magnitude of the difference in damage thresholds between the two different microstructures was strongly influenced by the size of the tested area. To better understand the microstructure effects, single layers of HfO{sub 2} with different microstructures were studied using transmission electron microscopy, ellipsometry, and a photothermal deflection technique. Since the laser damage initiated at defects, the influence of thermal diffusivity on thermal gradients in nodular defects is also presented.
Date: January 5, 1996
Creator: Stolz, C.J.; Genin, F.Y.; Kozlowski, M.R.; Long, D.; Lalazari, R.; Wu, Z.L. et al.
Partner: UNT Libraries Government Documents Department

Plasma synthesis of alumina films on metal and ceramic substrates

Description: The authors are exploring the feasibility of the plasma synthesis of highly-adherent films of alumina and chromia on SiC and FeAl substrates. A magnetically-filtered cathodic arc plasma deposition technique is used in which a high density metal plasma (Al or Cr) is formed and deposited on the substrate in the presence of a low pressure gaseous oxygen background. The substrate is simultaneously repetitively pulse biased, providing a means of controlling the incident ion energy. In the early stages of the process the ion energy is held in the keV range so as to produce atomic mixing at the film-substrate interface (ion stitching), and in the latter stages of deposition the energy is reduced to {approximately}200 eV (IBAD range) to provide a means of controlling the film structure and morphology. Films that are dense and highly adherent can be formed in this way. The authors have produced near-stoichiometric films of alumina and chromia on small SiC and FeAl substrates and characterized the films in a number of ways, including RBS, X-ray diffraction and adhesion, and we`ve also done some preliminary temperature cycling experiments. The alumina films are of thickness from 0.2 to 1.5.{micro}, amorphous prior to heat treatment, and show an {alpha}-alumina phase after heat treating at 1,000 C for up to 16 hours. The film substrate adhesion is typically greater then {approximately}70 MPa prior to heating, and initial results indicate that the films maintain their adhesion after repetitive cycling in temperature between ambient and 1,000 C. Here they describe the plasma processing method and outline the experimental results obtained to-date.
Date: April 1, 1995
Creator: Brown, I. & Wang, Zhi
Partner: UNT Libraries Government Documents Department

Investigation of optical loss mechanisms in oxide thin films

Description: KNbO{sub 3}, K(Ta,Nb)O{sub 3}, KTaO{sub 3}, and Ta{sub 2}O{sub 5} thin films have been grown by ion-beam sputter deposition. KNbO{sub 3} has excellent nonlinear properties for second harmonic generation; however, high optical losses are still characteristic of these films. Several loss mechanisms, such as, high angle grain boundaries, twin domains, interface and surface scattering, and oxygen vacancies can all contribute to the high losses. In order to isolate the various mechanisms, amorphous Ta{sub 2}O{sub 5} films, epitaxial cubic KTaO{sub 3} and tetragonal K(Ta,Nb)O{sub 3} films were grown on MgO and Al{sub 2}O{sub 3} substrates subjected to post-deposition annealing treatments and various oxygen pressure conditions. The optical losses and refractive indices were observed to differ depending on the substrate surface and annealing treatments. Resonant scattering experiments were performed to analyze the oxygen composition. The optical properties of these oxide thin film systems are reported and the breakdown of the loss mechanisms is addressed.
Date: May 1995
Creator: Chow, A. F.; Kingon, A. I.; Auciello, O. & Poker, D. B.
Partner: UNT Libraries Government Documents Department

Collisional effects of background gases on pulsed laser deposition plasma beams

Description: The penetration of energetic pulsed ablation plumes through ambient gases is experimentally characterized to investigate a general phenomenon believed to be important to film growth by pulsed laser deposition (PLD). Under typical PLD conditions involving background gases, the ion flux in the ablation plume is observed to split into distinct fast and slow components over a limited range of distances. The fast component is transmitted with near-initial velocities and high kinetic energies, potentially damaging to growing films at these distances. Formation of the second, significantly-slowed component correlates with the bright contact front formation observed in fast ICCD imaging studies. This general effect is explored in detail for the case of yttrium ablation into argon, a single-element target into an inert gas. Time-resolved optical absorption spectroscopy and optical emission spectroscopy are employed to simultaneously view the populations of both excited and ground states of Y and Y{sup +} for comparison with quantitative intensified-CCD photography of the visible plume luminescence and ion flux measurements made with fast ion probes during this phenomenon. These measurements confirm that, in addition to the bright significantly-slowed front which has been described by shock or drag propagation models, a fast-component of target material is transmitted to extended distances for some ambient pressures with near-initial velocities.
Date: April 1995
Creator: Geohegan, D. B. & Puretzky, A. A.
Partner: UNT Libraries Government Documents Department

Thin films of silicon on low-cost substrates. Quarterly project report No. 1, July 1, 1976-September 30, 1976

Description: The objective of this research program is to investigate the deposition of silicon on low-cost or temporary substrates using an Energy Beam. The Energy Beam consists of a central stream of partially ionized gas coupled to a source of RF energy. Thus a silicon bearing compound, injected into the gas stream, will decompose, either in the plasma or at the deposition substrate. The designs for the deposition chamber and the gas panel have been completed. A five kilowatt Energy beam system was received and a study of the Energy Beam plasma was initiated. Some preliminary experiments using a scanned laser beam for grain enhancement have been carried out. The construction of the deposition chamber and gas panel are now underway.
Date: January 1, 1976
Creator: Baghdadi, A.; Gurtler, R.W. & Keeling, M.C.
Partner: UNT Libraries Government Documents Department

Characterization and control of wafer charging effects during high-current ion implantation

Description: EEPROM-based sense and memory devices provide direct measures of the charge flow and potentials occurring on the surface of wafers during ion beam processing. Sensor design and applications for high current ion implantation are discussed.
Date: February 1, 1994
Creator: Current, M. I.; Lukaszek, W.; Dixon, W.; Vella, M. C.; Messick, C.; Shideler, J. et al.
Partner: UNT Libraries Government Documents Department

Electrostatic reduction of particulates for laser resistant hafnia coatings

Description: The authors have reduced by 50% particulate defect density of hafnia coatings deposited onto silicon substrates through the use of electric fields, physical barriers and deposition rate. In an effort to reduce the number of hafnia (HfO{sub 2}) particulates deposited onto silicon wafers, parallel plate electrodes were placed on either side of the evaporant plume. The particulate level was determined as the deposition rate was varied from 0.75 {angstrom}/sec to 12 {angstrom}/sec. Then, parallel plate electrodes were placed on either side of the plume as a way of electrostatically deflecting hafnia particulates away from the substrates. Later a single plate electrode was used in conjunction with a physical barrier placed over the hearth. The results of the study indicate that minimal defects occur when a parallel plate electric field is applied in conjunction with a fast deposition rate. Using a screen as a physical barrier, and/or a single electrode had little or no effect. This data may be useful in the manufacture of multilayer optical coatings with high laser damage thresholds.
Date: December 1, 1993
Creator: Miller, M. D.; Chow, R. & Loomis, G. E.
Partner: UNT Libraries Government Documents Department

Effect of niobium interlayer on high-temperature sliding friction and wear of silver films on alumina

Description: We investigated the effect of a thin Nb bond layer (15--20 mn thick) on the high-temperature sliding friction and wear of silver films ({approx}1.5 {mu}m thick) produced on {alpha}-alumina (Al{sub 2}O{sub 3}) substrates by ion-beam assisted deposition. The friction coefficients of test pairs without an Ag film fluctuated between 0.8 to 1.1, whereas the friction coefficients of pairs with an Ag film were 0.32 to 0.5. The wear of uncoated Al{sub 2}O{sub 3} balls sliding against the Ag-coated flats was reduced by factors of 25 to {approx}2000, depending on test temperature and the presence or absence of an Nb bond layer. The wear of silver-coated flats was virtually unmeasurable after tests at temperatures up to 400C. At much higher temperatures (e.g., 600C), Ag films without an Nb bond layer delaminated from the sliding surfaces and lost their effectiveness; however, Ag films with an Nb bond layer remained intact on the sliding surfaces of the Al{sub 2}O{sub 3} substrates even at 600C and continued to impart low friction and low wear.
Date: March 1, 1994
Creator: Erdemir, A. & Erck, R. A.
Partner: UNT Libraries Government Documents Department

Resonant holographic measurements of laser ablation plume expansion in vacuum and argon gas backgrounds

Description: This thesis discusses the following on resonant holographic measurements of laser ablation plume expansion: Introduction to laser ablation; applications of laser ablation; The study of plume expansion; holographic interferometry; resonant holographic interferometry; accounting for finite laser bandwidth; The solution for doppler broadening and finite bandwidth; the main optical table; the lumonics laser spot shape; developing and reconstructing the holograms; plume expansion in RF/Plasma Environments; Determining {lambda}{sub o}; resonant refraction effects; fringe shift interpretation; shot-to-shot consistency; laser ablation in vacuum and low pressure, inert, background gas; theoretically modeling plume expansion in vacuum and low pressure, inert, background gas; and laser ablation in higher pressure, inert, background gas.
Date: October 1, 1993
Creator: Lindley, R. A.
Partner: UNT Libraries Government Documents Department

Selective IR reflective coatings development. Semiannual report, July 24, 1978-January 24, 1979

Description: Two low temperature deposition technques, a glow discharge activation technique and an ion plating technique, were investigated as methods for coating thin plastic membranes with solar transparent, infrared reflective semiconducting oxides. The glow discharge activation technique was shown to produce coatings with better optical properties than the ion plating technique. Repeatability of coating properties with the glow discharge technique has been a problem whose solution appears to lie in better deposition process control.
Date: January 1, 1979
Creator: Lefkow, A R
Partner: UNT Libraries Government Documents Department

Orientation selection and microstructural evolution of epitaxial platinum films on (001) magnesium oxide

Description: Thin platinum films were deposited at several different deposition rates and with varying thickness on (001)-cut MgO single crystal substrates by electron beam evaporation. A mixture of two epitaxial Pt orientations were detected in the films by X-ray diffraction and planar ion channeling experiments: (001)[100]Pt // (001)[100]MgO (the [open quotes]cube-on-cube[close quotes] orientation) and (111)[110]Pt // (001)[110]MgO. The effect of deposition rate on film orientation indicated the (111)Pt orientation was preferred under conditions of high driving force for nucleation. The volume fraction of the films occupied by the (111) orientation increased with nominal film thickness, at a constant substrate temperature and deposition rate. This result indicates crystallites having the (111)Pt orientation grew more quickly following nucleation than the (001). The mosaic spread of the Pt orientation decreased markedly as the nominal film thickness increased from [approximately] 1.5 nm (isolated islands) to 20 nm (continuous film).
Date: January 1, 1995
Creator: McIntyre, P.C.; Maggiore, C.J. & Natasi, M.
Partner: UNT Libraries Government Documents Department

Formation of aluminum films on silicon by ion beam deposition: A comparison with ionized cluster beam deposition

Description: The direct ion beam deposition (IBD) technique has been used to study the formation of oriented aluminum films on single crystal silicon substrates. In the IBD process, thin film growth is accomplished by decelerating a magnetically-analyzed ion beam to low energies (10--200 eV) for direct deposition onto the substrate under UHV conditions. The energy of the incident ions can be selected to provide the desired growth conditions, and the mass analysis ensures good beam purity. The aluminum on silicon system is one which has been studied extensively by ionized cluster beam (ICB) deposition. In this work, we have studied the formation of such films by IBD with emphasis on the effects of ion energy, substrate temperature, and surface cleanliness. Oriented films have been grown on Si(111) at temperatures from 40{degree} to 300{degree}C and with ion energies from 30 to 120 eV per ion. Completed films were analyzed by ion scattering, x-ray diffraction, scanning electron microscopy, and optical microscopy. Results achieved for thin films grown by IBD are compared with results for similar films grown by ICB deposition. 15 refs., 3 figs.
Date: January 1, 1990
Creator: Zuhr, R.A.; Haynes, T.E.; Galloway, M.D. (Oak Ridge National Lab., TN (USA)); Tanaka, S.; Yamada, A. & Yamada, I. (Kyoto Univ. (Japan). Ion Beam Engineering Lab.)
Partner: UNT Libraries Government Documents Department

ECR plasma-assisted deposition of Al{sub 2}O{sub 3} and dispersion-strengthened AlO{sub 2}

Description: Electron cyclotron resonance (ECR) O{sub 2} plasmas, in conjunction with electron-beam evaporation of Al, were used to grow thick AlO{sub x} films were varying but controlled composition and microstructure. The ion energy was varied from 30 to 190 eV, and growth temperatures varied from 35{degrees}C to 400{degrees}C. The ECR-film compositions were varied from AlO{sub 0.1} to Al{sub 2}O{sub 3} by controlling the plasma parameters and Al deposition rate. The Al-rich alloys exhibited a fine-grain (10-100 nm) fcc Al microstructure with {gamma}-Al{sub 2}O{sub 3} precipitates ({approximately}1 nm), similar to that found in the gigapascal-strength O-implanted Al. The measured hardness of the ECR Al-O alloys ({approximately}3 GPa) was also similar to the ion-implanted alloys which implies that the yield strength of the ECR material is {approximately}1 GPa. Moreover, the Al-O alloys retain much of the elasticity of the Al metal matrix. As-deposited stoichiometric Al{sub 2}O{sub 3} samples grown with an applied bias of -140 to -160 V at 400{degrees}C were fine-grain polycrystalline {gamma}-Al{sub 2}O{sub 3}. The amorphous films crystallized into the {gamma}-Al{sub 2}O{sub 3} phase upon vacuum annealing to 800{degrees}C.
Date: March 1, 1995
Creator: Barbour, J. C.; Follstaedt, D. M. & Myers, S. M.
Partner: UNT Libraries Government Documents Department

Uses of ion bombardment in thin-film deposition

Description: Use of plasma- and ion-beam-modified surfaces and surface coatings in continually expanding in engineering disciplines. The purpose of these modifications and treatments is to impart favorable properties, such as wear resistance and lubricity, to the surfaces, while at the same time retaining the strength or toughness of the bulk materials. Energetic-ion bombardment can be used to modify the structural and chemical properties of surfaces or applied coatings. Ion-implantation has been used for many years, and recently, other surface-modification techniques, among them ion-beam mixing and ion-beam-assisted deposition, have attracted attention because they permit application of highly adherent lubricious and wear-resistant films. In this paper, ion-beam techniques are described from the viewpoint of ion-surface interactions, and some avenues for the engineering of tribological surfaces are presented. 100 refs., 4 figs.
Date: October 1, 1990
Creator: Erck, R.A.; Fenske, G.R. & Erdemir, A.
Partner: UNT Libraries Government Documents Department

Ion beam and defect-related research in the Solid State Division. [LiNbO/sub 3/, Al/sub 2/O/sub 3/]

Description: This paper contains viewgraphs on the topic of radiation effects of solid state materials. In particular, it elaborates on ion beam deposition of thin film structures, ion implantation damage in crystals of Al/sub 2/O/sub 3/, and ion implanted optical waveguides in LiNbO/sub 3/. (LSP)
Date: August 5, 1986
Creator: Roberto, J.B.
Partner: UNT Libraries Government Documents Department

Microstructure of epitaxial YBa sub 2 Cu sub 3 O sub 7 thin films

Description: Thin epitaxial films of YBa{sub 2}Cu{sub 3}O{sub 7} on single crystal substrates have been prepared in situ by laser ablation and by post situ annealing of evaporated films of Cu, Y and BaF{sub 2}. Substrates include (001) SrTiO{sub 3}, LaGaO{sub 3}, and LaAlO{sub 3}. For both in situ and post situ annealed films, epitaxial (001) grains of YBa{sub 2}Cu{sub 3}O{sub 7} form near the substrate but (100) and (010) grains tend to nucleate for thicknesses greater than {approximately}0.5{mu}m. 90{degree} grain boundaries are therefore common, as well as other defects such as small angle boundaries dislocations and stacking faults. High resolution electron microscopy of the substrate/superconductor interface shows regions of perfect epitaxy, distorted areas, amorphous regions and areas of interdiffusion. The relationship of observed microstructure to critical current density is discussed. 21 refs., 15 figs.
Date: January 1, 1990
Creator: Mitchell, T.E.
Partner: UNT Libraries Government Documents Department

Deposition, fabrication and analysis of polycrystalline silicon MIS solar cells. Final Report, January 1-December 31, 1979

Description: Discussion of MIS cell fabrication techniques, protovoltaic response data, I-V-T analysis to reveal conduction mechanisms, a detailed computer model, optimum MIS solar cell design, surface state effects, Auger studies, reliability studies and e-beam deposition of thin silicon films are included. The most important features of the work during 1979 include the one pump-down fabrication process, establishing a consistent fabrication sequence, achieving 13% efficiency of 2 cm/sup 2/ area, an evaluation of conduction mechanisms, establishing a detailed computer model and setting up an improved e-beam system to deposit thin silicon films. Details are reported. (WHK)
Date: March 1, 1980
Creator: Anderson, W.A.
Partner: UNT Libraries Government Documents Department

Growth of high Tc superconducting thin films for microwave applications

Description: High-{Tc} superconducting thin films of YBa{sub 2}Cu{sub 3}O{sub 7 {minus}{delta}} (YBCO) were deposited on sapphire substrates with buffer layers of yttria-stabilized zirconia and cerium oxide by using pulsed laser deposition (PLD) technique. The epitaxial relationship between the substrate and buffer layers as well as the buffer layer and the superconducting film was established. Furthermore, using the same thin film technique, YBCO superconducting thin films were deposited on both sides of substrates of up to 5 cm in diameter. The superconducting properties of the films on both the sapphire with buffer layers and large-area substrates were comparable to the ones of the best YBCO films. 8 refs., 6 figs.
Date: January 1, 1991
Creator: Wu, X.D.; Foltyn, S.R.; Muenchausen, R.E.; Dye, R.C.; Cooke, D.W.; Rollett, A.D. et al.
Partner: UNT Libraries Government Documents Department