Showing papers by "Emmanuel P. Giannelis published in 1993"
1,123 citations
361 citations
TL;DR: In this article, the optical absorption edge is red shifted with respect to that of an epitaxially grown single-crystal film of γ-Fe2O3, attributed to lattice strain in the small particles.
Abstract: γ-Fe2O3 nanocrystals with a mean radius of 4.2 nm have been synthesized in a polymer matrix by an ion exchange and precipitation reaction. Magnetization and susceptibility data from experiment and computer simulations indicate that the system is superparamagnetic. The optical absorption edge is red shifted with respect to that of an epitaxially-grown single-crystal film of γ-Fe2O3. The red shift is attributed to lattice strain in the small particles.
187 citations
TL;DR: In this article, the density and chemical composition of the highest-dose implanted sol-gel zirconia films were comparable with those obtained by high-temperature sintering, attributed to both electronic interactions and nuclear collisions between the Xe+ ions and the target atoms.
Abstract: Densification of sol–gel zirconia films was achieved using ion implantation instead of conventional heat treatment. Densification was observed with Xe+-ion doses as low as 1014 ions/cm2. Ion implantation resulted in hydrogen and carbon losses as measured by forward recoil elastic spectrometry (FRES) and Rutherford backscattering spectrometry (RBS) using 12C(α,α)12C resonance, respectively. The density and chemical composition of the highest-dose implanted sol–gel films were comparable with those obtained by high-temperature sintering. The chemical and microstructural modifications in the films were attributed to both electronic interactions and nuclear collisions between the Xe+ ions and the target atoms.
31 citations
TL;DR: In this paper, Ba0.75Sr0.25TiO3 thin films have been deposited on single-crystal MgO substrates by pulsed laser deposition with the objective of forming ferroelectric films with a low Curie temperature.
Abstract: Ba0.75Sr0.25TiO3 thin films have been deposited on single-crystal MgO substrates by pulsed laser deposition with the objective of forming ferroelectric films with a low Curie temperature. The films have been characterized by capacitance measurements and by transmission electron microscopy, x-ray diffraction, and Rutherford backscattering spectrometry (random and channeled). Films deposited with the substrate at 500 °C are polycrystalline, while those deposited at 650 °C are highly aligned and possibly epitaxial. The films are transparent in the visible region with an optical absorption edge at about 300 nm. Capacitance measurements on the polycrystalline films reveal a Curie transition at 283 K. The lowering of Curie temperature from the corresponding bulk sample is attributed to the films being under compression, as verified by Raman spectroscopy.
20 citations
TL;DR: In this article, the authors used diverse matrices, such as an ion exchange resin or a porous glass, to prepare stable nanocomposites of several materials including iron oxide and lead iodide.
16 citations
TL;DR: Spin-on oxide films, natural candidates for improving interlevel dielectric planarization in ULSI circuits, are reviewed in this article, where a thin film is produced by spin-casting a liquid on a rotating wafer.
Abstract: Spin-on oxide films, natural candidates for improving interlevel dielectric planarization in ULSI circuits, are reviewed The spin-on process, one in which a thin film is produced by spin-casting a liquid on a rotating wafer, is described Spin-on films combine the planarization capabilities of a fluid with the dielectric properties of an oxide They fill all the lower regions over the wafer and produce a planar top layer Spin-on insulators can be used in combination with chemically-vapor-deposited (CVD) materials, and can also be combined with an etchback step to improve planarization As a result, the depths of vias in the etching process can be made more uniform, and voids in the filling of via-contacts, which become a significant problem as the via size shrinks, can be eliminated >
11 citations
TL;DR: The authors showed that desorption of Type I water from the anatase crystals is accompanied by a decrease in the refractive index but no densification, while desorbing of Type II water or surface hydroxyls at higher temperatures leads to film densification but has no apparent effect on the The authors.
Abstract: Films consisting of discrete anatase crystals with an average diameter of 8 nm were deposited from a colloidal sol synthesized from titanium(IV) isopropoxide. From ion-beam analysis (FRES and RBS) and ellipsometry, we found that desorption of Type I water from the films is accompanied by a decrease in the refractive index but no densification. Conversely, desorption of Type II water or surface hydroxyls at higher temperatures leads to film densification but has no apparent effect on the refractive index. The densification involves progressive condensation of hydrogen-bonded hydroxyls and finally isolated hydroxyls. The refractive index for films exposed to air for 6 months increases regardless of heat treatment because of surface rehydration which nearly recreates the original surface.
9 citations
TL;DR: In this paper, the interface width between a titanium dioxide and a silicon dioxide film deposited by sol-gel processing was measured using reflectometry, and it was shown that the width is the same as the roughness of a solgel silicon dioxide surface after the same heat treatment.
Abstract: Neutron reflectometry (NR) was used to directly measure the interface width between a titanium dioxide and a silicon dioxide film deposited by sol-gel processing. In a bilayer heated to 450 C, NR measurements showed that the interface width is 0.8 nm. This width is the same as the roughness of a sol-gel silicon dioxide surface after the same heat treatment, suggesting no interdiffusion or mixing at the bilayer interface.
3 citations
TL;DR: In this paper, the densification behavior of sol-gel zirconia films resulting from ion irradiation was investigated, and three sets of films were implanted with neon, krypton, or xenon.
Abstract: 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.
2 citations
TL;DR: In this article, the 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.
Abstract: 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.
21 May 1993
TL;DR: In this paper, the properties of spin-on titanium-nitride (SO-TiN) thin films were optimized for integrated- circuit application, and the two steps of the spinon process were characterized: one, the initial step in which a thin-film titanium oxide is formed, and two, the conversion of the thin film to TiN by rapid thermal processing in ammonia.
Abstract: The properties of spin-on titanium-nitride (SO-TiN) thin films were optimized for integrated- circuit application. The two steps of the spin-on process were characterized: one, the initial step in which a thin-film titanium oxide is formed, and two, the conversion of the thin film to titanium-nitride (TiN) by rapid thermal processing in ammonia. The spin-on TiN showed a uniform coating on a flat wafer surface for all the precursors. However, on non-planar topography some solutions produced cracked films while others did not. The precursor's effect was investigated, and it is proposed that the optimized precursor should include more carbon in the initial annealing stage so the film does not crack. The chosen precursor, titanium- tertiary-butoxide, was investigated and characterized versus processing temperature, heating rate, and gas flow. The experiment was designed at the 700 degree(s)C - 1000 degree(s)C temperature range, with 0.1 - 200 degree(s)C/sec. heating rate, and hold time of 30 - 300 sec. at the upper temperature before rapid cool down. The optimal processing conditions at NH3 are heating at 100 - 120 degree(s)C/sec. ramp from room temperature up to 900 degree(s)C - 1000 degree(s)C where the wafer is annealed for 30 - 100 seconds before rapid cool down to room temperature.© (1993) COPYRIGHT SPIE--The International Society for Optical Engineering. Downloading of the abstract is permitted for personal use only.