The thermal stability of Ag(Cu) alloy thin films on indium tin oxide (ITO) has been investigated and compared to that of pure Ag thin films on ITO. Atomic force microscopy and X-ray diffraction results of annealed films show differences in the evolution of surface morphology and texture with annealing. The presence of Cu atoms in the silver impacts the surface energy and surface diffusion. This results in Ag and Ag(Cu) alloy having very different surface morphology and crystallographic texture. The enhanced texture and thermal stability of the Ag(Cu) alloy constitute its potential use contact as material for MOSFET and for flip-chip light-emitting diodes.

TiAl based thin-films possess high oxidation-resistance and high melting points, making them possible candidates for application in electronics. The behavior of the films upon exposure to various temperatures is of interest for such application. In the present study, Ti37Al63 thin films were deposited onto SiO2 substrates using RF magnetron sputtering from a compound target. Anneals were performed in vacuum at temperatures ranging from 400 °C to 700 °C. The phases and microstructural behavior of the films were evaluated as a function of annealing. Microstructural behavior was correlated with resistivity changes in the films. The behavior of Ti-Al films as potential under-layers for silver metallization was also evaluated. The Ti-Al was observed to enhance the thermal stability of pure Al thin-films. The results are relevant for potential application of the films to electronics.

The thermal stability and electrical resistivity of Ag(Al) alloy thin films on SiO2 are investigated and compared to pure Ag thin films by performing various analyses: Rutherford backscattering spectrometry (RBS), X-ray diffractometry (XRD), transmission electron microscopy (TEM), and four-point probe. The susceptibility to agglomeration of Ag on SiO2 layer is a drawback of Ag metallization. Ag(Al) thin films show good thermal stability on SiO2 layer without any diffusion barrier. The films are stable up to 600 °C for 1 hour in vacuum. Electrical resistivity of as-deposited Ag (5 at % Al) thin film is slightly higher than that of pure Ag thin film. However, the resistivity of Ag(Al) samples annealed at high temperatures (up to 600 °C for 1 hour in vacuum) remains constant due to the improvement of thermal stability (large reduction of agglomeration). This finding can impact metallization for thin film transistors (TFT) for displays, including flexible displays, and high-speed electronics due to lower resistivity value compared to Cu thin film.

We have investigated successfully the hydrogen concentration of samples of modern roof tile from the Shanghai Roof Tile and Brick Works. The intent of the investigation is to determine the applicability of ion beam analysis in the form of Forward Recoil Energy Spectrometry (FRES) to the analysis of the hydrogen content of the samples. We can measure hydrogen introduced during firing in modern bricks that we know were fired using hydrogen reduction. Completion of this feasilibity test allows us to propose sampling and testing ancient Chinese ceramics and to use the modern roof tile samples as a baseline for comparison.

The mixing of titanium overlayers with hydroxyapatite (HA) substrates via ion irradiation has been demonstrated. Analysis via secondary ion mass spectroscopy (SIMS) indicates an interfacial broadening of titanium and calcium of the implanted sample compared to that of the unimplanted sample. Attendant to the observed ion beam mixing of titanium into the HA, the oxygen signal of the titanium overlayer increases as a result of ion irradiation. It is supposed that this change is evident of diffusion through the metal layer and possibly from titania formation at the free surface and perovskite formation at the film/substrate interface. This possibility is consistent with thermodynamic predictions. Additionally, the force required to separate the film from the substrate increased as a result of ion irradiation, validating the continued study of ion beam processing of Ti/HA systems towards the improvement of long term fixation of implant devices.

We have investigated the tribomechanical properties of ion-beam-densified sol-gel zirconia overlayers on bulk zirconia. Ion irradiation of the sol-gel films leads to hydrogen, oxygen, and carbon losses as indicated by Rutherford backscattering spectrometry and forward recoil energy spectroscopy. Ellipsometry measurements show that the film thickness decreases with increasing dose. The microhardness exhibits an increase and subsequent decrease with dose. Friction measurements along with profilometry measurements indicate that severe abrasive wear of the film takes place in the first 1000 cycles after which point the substrate is in direct contact with the pin.

Amorphous carbon was evaluated as a diffusion barrier between Cu and Si. Samples were annealed at 500 ºC for 1 hour in vacuum. Barrier properties were characterized for metallurgical failure with RBS and XTEM, and electrical properties were characterized with pn junction diodes and MOS capacitors. RBS and X-TEM showed that a barrier 13.5 nm thick prevented Cu and Si diffusion during the anneal. The diodes remained rectifying after annealing, although the series resistance went up. C-V measurements of the capacitors did not show the hysteresis that is typical of mobile charge in the oxide. The barrier breakdown mechanism is diffusion through the amorphous structure.

We have investigated the densification behavior of sol-gel zirconia films resulting from ion irradiation. Three sets of films were implanted with neon, krypton, or xenon. The ion energies were chosen to yield approximately constant energy loss through the film and the doses were chosen to yield similar nuclear energy deposition. Ion irradiation of the sol-gel films resulted in carbon and hydrogen loss as indicated by Rutherford backscattering spectrometry and forward recoil energy spectroscopy. Although the densification was hypothesized to result from target atom displacement, the observed densification exhibits a stronger dependence on electronic energy deposition.

Recent work by the authors has been extended to demonstrate the formation of solid krypton in single-crystal magnesium oxide. The solid inclusions, which were formed by ion implantation at room temperature, have been identified by electron diffraction. The formation of solid noble gas inclusions at room temperature indicates that they were under a high pressure. This pressure was determined, based on the measured lattice parameter, to be 1.7 GPa.

Co-evaporated Cu-Ti films on thermally-oxidized Si substrates were annealed in vacuum at temperatures between 300 and 700°C. Reactions within the films and between film and substrate were monitored by Rutherford backscattering spectrometry, X-ray diffraction, transmission electron microscopy and sheet resistance. We found that, despite the competition from intermetallic compound formation, the Cu-Ti films react with SiO2 beginning at 400°C, with Ti migrating to the SiO2 interface to form both a suicide, Ti5Si3, and an oxide and to the free surface to form additional oxide. The reaction leaves relatively pristine Cu. Above 600°C, however, Cu begins to react with the underlying suicide. By comparison, pure Ti reacts with SiO2 only above ∼700°C.

The transport of germanium through a co-deposited palladium-silicon layer on epitaxially grown GexSi1−x on Si(100) was studied. The Ge concentration in the UHV-CVD grown GexSi1−x film was x=.14 with a thickness of 155 nm. When the co-deposited layer is Pd rich with respect to Pd2Si, Ge was found to move through the Pd-Si layer and grow polycrystalline on the GexSi1−x. Ge transport and Pd2Si(111) grain growth ceased simultaneously. No transport was found for Si rich Pd-Si layers. Electrical characterization showed the contacts were ohmic with a specific contact resistivity between 6–12 μωQ-cm2 and an end resistance of.75 ω, resulting in a carrier concentration under the contact of 1.5×1014 cm−2. Hall effect measurements of the semiconductor gave n=5.77×1014 cm−2 and μ=36.96 cm−2/Vs. The sheet resistance of the contact layer was found to be 23.54 ω/square and the semiconductor was 237 ω/square.

At Cornell University we are in the third year of teaching an interdisciplinary, undergraduate course on the physical properties and structures of works of Art, and the modern analytical methods used to investigate them: Art, Isotopes, and Analysis. The challenge is to explain concepts familiar to museum scientists and conservators to a group of 150 undergraduate students with a background that ranges from Art History to Computer Science. Painting techniques (Fresco, Tempera, Oil, etc.) are demonstrated to the class. The analytical techniques involve the interactions of electrons, photons, ions and neutrons with pigments and other materials. This instructional approach serves as an introduction to published analyses of works of art.

Co-evaporated Cu-Ti films on thermally-oxidized Si substrates were annealed in vacuum at temperatures between 300 and 700° C. Reactions within the films and between film and substrate were monitored by Rutherford backscattering spectrometry, X-ray diffraction, transmission electron microscopy and sheet resistance. We found that, despite the competition from intermetallic compound formation, the Cu-Ti films react with SiO2 beginning at 400°C, with Ti migrating to the SiO2 interface to form both a silicide, Ti5Si3, and an oxide and to the free surface to form additional oxide. The reaction leaves relatively pristine Cu. Above 600°C, however, Cu begins to react with the underlying silicide. By comparison, pure Ti reacts with SiO2 only above ˜700°C.

We have used the TRIGA reactor and the Ion Beam Facility at Cornell to illustrate neutron induced autoradiography and PIXE analysis of known pigments in demonstration paintings made for our undergraduate course, ‘Art, Isotopes and Analysis’. A group of pigments were chosen containing elements with half-lives detectable by the neutron activation process. The pigments (suspended in a binding medium of linseed oil) were first painted on test swatches of acetate and their characteristic x-ray lines measured with a 5 Mev beam of protons directed through a thin Kapton film for external (in air) analysis (PIXE).

Three layers of images, each painted with a different pigment, overlay one another. The painting is then taken to the TRIGA reactor for neutron activation. After activation, the painting is placed in contact with sheets of Polaroid type AR positive transparency film at different times after exposure. The gamma spectra during the sequence are also measured to provide identification of the ‘active’ isotopes during each film exposure.

Thin films of barium titanate (BaTiO3) have been deposited by pulsed-laser ablation onto (001)-oriented MgO substrates. The films were epitactic with the c-axis perpendicular to the film-substrate interface, as evidenced by both transmission electron microscopy (TEM) and ion-channeling techniques. The elastic resonance of 3.045 MeV α-particles, generating the 16O(α, α)16O reaction was used to determine the oxygen stoichiometry of the film and the minimum yield based on the oxygen peaks, thereby enabling conclusions to be drawn about the crystalline perfection of the oxygen sublattice.

Ion-channeling and transmission electron microscopy (TEM) techniques were used to examine the microstructure of single-crystal Y2O3 stabilized cubic zirconia (YSZ) after implantation with 240 keV Xe+ ions. The observed microstructure was related to Knoop indentation hardness measurements. These measurements showed an increase in hardness for low ion-doses, reaching some maximum value, then a decrease in hardness at higher doses. In the hardening regime, below 7.5 × 1015 Xe+/cm2, point defects and dislocation networks were observed by TEM. Ion-channeling showed a corresponding increase in damage as a function of ion-dose. For doses between 7.5 × 1015 and 3 × 1016 Xe+/cm2 the hardness falls, and the amount of damage, measured with ion-channeling, reaches a limiting value at less than complete damage. In this dose range the Xe concentration continues to increase beyond the dose where the amount of damage saturates. For high doses, greater than 3 × 1016 Xe+/cm2, where softening of the zirconia occurs, additional reflections appear in the electron diffraction pattern that are consistent with the lattice parameter of solid Xe. A diffuse ring is also visible; this is believed to be due to the presence of fluid Xe. Both ion-channeling and TEM show that a significant amount of monocrystalline zirconia remains even up to doses of 1 × 1017 Xe+/cm2. There is also evidence for the presence of recrystallized zirconia at the high doses. Since so much crystalline material remains, it seems that amorphization of the zirconia is not the dominant cause of the softening at high doses.

The microstructure of BaTiO3 thin-films deposited on MgO by pulsed-laser ablation has been examined by both scanning and transmission electron microscopy. The films were epitactic as evidenced by electron diffraction studies. Preliminary capacitance measurements on these films have shown clear evidence for a ferroelectric phase transition at ∼110°C.