Y2O3 Films Research Articles

Characteristics of oxide thin films from carboxylate precursors

Oxide thin films on Si substrates were prepared from carboxylate precursors by the reaction of the metal nitrates and ammonium trimethylacetate. Precursor salts were characterized with respect to purity, structure, thermal pyrolysis, and phase development during calcination. A solvent system, based on carboxylic acid/amine mixture, was developed to dissolve the synthesized precursors, resulting in increased solubility, viscosity, and stability. Smooth, fine-grained ZrO2, Y2O3, and YSZ films were obtained on Si wafers by spin-coating and subsequent heat treatment above 500 °C. Films heat treated below 700 °C were generally adherent, amorphous, or microcrystalline, while YSZ and ZrO2 showed (111) preferred orientation above 700 °C. These oxide films show promise as protective or buffer layers on Si wafers.

Preparation and magneto-optic properties of Bi-substituted yttrium iron garnet thin films by metalorganic chemical vapor deposition

Magneto-optic bismuth-substituted yttrium iron garnet thin films were epitaxially grown during deposition for the first time by metalorganic chemical vapor deposition. Triphenyl bismuth and both yttrium and iron tridipivaloylmethane were used as source materials. Prior to the preparation of garnet films, the deposition behavior of Y2O3, Fe2O3, and Bi2O3 films was examined separately. Epitaxially grown films were as-deposited on a Gd3Ga5O12(111) substrate at 750 °C under a reduced pressure of 6 Torr with a deposition rate of 200–500 Å/min, which is about 10 times faster than that obtained by the conventional sputtering method. A film with a bismuth content of 2.5 atoms per formula unit showed a large Faraday rotation, − 7.5 × 104 deg/cm at λ=633 nm, because of the high bismuth substitution and the crystalline perfection.

Chemical Beam Deposition of Y2O3 Thin Films with An Ecr

ABSTRACTStoichiometric thin films of Y2O3 have been deposited on Si at substrate temperatures as low as 300 °C by plasma enhanced chemical vapor deposition using an electron cyclotron resonance (ECR) source. The yttrium source was an organo-metallic compound which was sublimated and fed with He carrier gas into the reactor chamber. Good capacitance-voltage characteristic curves were obtained for the dielectric film and a relative electrical permittivity of 9.9 was measured. This technique is a useful means of depositing oxide ceramic films at low substrate temperatures.

Dielectric properties of rf-sputtered Y2O3 thin films

Yttrium oxide (Y2O3) thin films were deposited on indium-tin-oxide(ITO)-coated glass substrates by the radio-frequency-sputtering method using an Y2O3-sintered target. The relative dielectric constant εr and the dielectric strength EBD of the Y2O3 films were studied. It was found that εr and EBD have a maximum value and a minimum value, respectively, at 1.3 Pa when the pressure of the sputtering gas, Ar+10% O2, is varied from 0.67 to 9.3 Pa. The x-ray diffraction study showed that the Y2O3 films deposited at 1.3 Pa are predominantly oriented along the 〈332〉 direction and their grain size is the smallest. Ion mass analysis showed impurity diffusion from ITO in the films deposited at 1.3 Pa. Furthermore, the dielectric properties of the Y2O3 films deposited at 1.3 Pa are related to the structural properties, such as the 〈332〉 orientation, grain size, and impurity diffusion.

Low-pressure metalorganic chemical vapor deposition of photoluminescent Eu-doped Y2O3 films

We have produced thin photoluminescent films of Eu-doped Y2O3 (Y2O3: Eu) by low-pressure metalorganic chemical vapor deposition (MOCVD). Yttrium and europium β-diketonate precursors are thermally decomposed in a hot-walled MOCVD reactor in the presence of oxygen at a total reactor pressure of 1 Torr. The films are microcrystalline and photoluminescent as-deposited and contain <1 at.% of carbon contamination. Subsequent annealing at 1200°C in air enhances and stabilizes the luminescence. We have measured the photoluminescent lifetimes of the MOCVD films as a function of temperature for the Eu+35D1 ⇉ 7F1 and 5D0 ⇉ 7F2 transitions using excimer laser excitation at 248 nm. We present a kinetic model which can account for the observed emission lifetimes from 20–1000°C.

Deposition of oxide films by metal-organic molecular-beam epitaxy

Molecular-beam epitaxy (MBE) has been used in tandem with a unique class of metallo-organic precursors to deposit thin films of Cu, Y2O3, and BaF2 on (100) MgO substrates. The temperatures of deposition were 400, 500, and 625 °C. It was found that the presence of an activated oxygen species, such as ozone, was required to obtain a film product. The influence of oxidizing environment and substrate temperature on precursor decomposition and deposition yield are described.

Heteroepitaxial growth of Y2O3 films on silicon

Yttria (Y2 O3 ) films have been grown on Si (100) and Si (111) substrates heated at 800 °C by vacuum evaporation. X-ray diffraction and reflection high-energy electron diffraction observations reveal the heteroepitaxial growth of Y2 O3 films on Si (100) and Si (111) substrates. The (111) oriented Y2 O3 films are grown directly on Si (111) substrates. The (100) oriented Y2 O3 films are grown on the thin (Y2 O3 )0.09 (ZrO2 )0.91 layer predeposited on Si (100) substrates instead of direct growth on Si (100) substrates.

Analysis of interface states in CaS/Y2O3/SiO2/ITO multilayer thin films by AES.

Interface states between an insulating layer and a transparent electrode were investigated, being concerned with the stability and the luminescent properties of CaS thin film electroluminescent (EL) devices. It was found that Y2O3 and CaS thin films deposited on an ITO transparent electrode at 500°C were peeled off when these films were heat-treated at 500°C for one hour. The peeling-off is thoroughly prevented by inserting a SiO2 thin film as a buffer layer between the Y2O3 and ITO films. It was shown that the luminescent properties of the EL device was also improved by using the SiO2 buffer layer. The roles of the buffer layer are discussed from the results of the elemental depth profile measured by Auger electron spectroscopy.

Application of Waveguide Raman Spectroscopy to High-Index Dielectric Films

Waveguide Raman spectroscopy has been applied to the analysis of single-layer, refractory-oxide, thin-film coatings on fused silica. With the use of the film as a waveguide, the interaction of the laser probe beam with the film is maximized, and interference from the silica substrate is minimized. An amorphous film of Ta2O5 was found to be an excellent waveguide, yielding an intense Raman spectrum. Even though polycrystalline films of Y2O3, ZrO2, HfO2, and ThO2 were found to be poor waveguides, they still yielded Raman spectra containing useful structural information. Such Raman spectra showed that the ThO2 film was initially in an unusual structural form, which spontaneously transformed into cubic ThO2. Even for films yielding relatively weak Raman bands, substrate Raman scattering was not a serious interference. Representative spectra are presented, along with a brief discussion of the requirements for coupling optical beams into films with large refractive indices.

Nanometer-scale structures produced in oxide films

Rapid material removal has been found to occur in a number of metal halide and oxide films at the point of exposure to a high intensity electron beam. As a result, 3-dimensional, nanometer scale (1-100 nm) structures have been produced in these materials. Possible applications of these systems include substrates for high density E-beam data storage and E-beam resist materials for mask fabrication. Other potential applications would include processes where controlled patterning on a nanometer scale is desirable. In this study amorphous thin films of ZrO2, Y2O3 and AI2O3 were deposited onto coated Cu-grid substrates and the mechanism whereby E-beam interaction promoted rapid material removal on a nanometer scale was explored.Films less than 200 nm in thickness were prepared in a Perkin-Elmer Randex 3140-6J sputtering system. Deposition of films directly onto 20 mesh formvar coated TEM grids facilitated handling and allowed immediate analysis by EM techniques.

The structure and electroluminescent characteristics of ZnS:Mn thin films

The dependence of structure and the electroluminescent properties of ZnS:Mn thin films on the substrate temperature has been investigated. The samples were electron-beam deposited on polycrystalline Y2O3 film and quartz glass substrates. Reflection high-energy electron diffraction experiments showed that the films had a zinc-blende structure and were composed of a double-fiber structure with the two [111] axes inclined at an angle to the substrate at substrate temperatures between 25 and 180 °C. At 200 °C substrate temperature the films consisted of a single-fiber structure with the [111] axis nearly perpendicular to the substrate surface. Electron-spin resonance measurements indicated that Mn2+ content in the films was nearly constant at substrate temperatures above 140 °C but steeply decreased below this temperature. Maximum electroluminescent intensity was obtained when the films were produced at 200 °C substrate temperature.

Luminescence of Y2O3 Films during Anodization of Yttrium

Luminescence of Y2O3 Films during Anodization of Yttrium

Reactively Evaporated Films of Scandia and Yttria

Sc(2)O(3) and Y(2)O(3) films were prepared by evaporation from resistance heated boats in a residual gas atmosphere of oxygen. Films of much lower absorptance were obtained than from coatings produced in high vacuum. The short wavelength limit of high transparency was between 300 nm and 400 nm, while the long wavelength absorption edge was reached at about 11 microm. Refractive indices of 1.8-2.0 were measured for both oxides. The influence of annealing on the optical- properties of the films was investigated. The films were amorphous and proved to be mechanically very stable and water resistant. Electron micrographs showed smooth and uniform surfaces. By antireflection coatings of yttria the transmittance of silicon was increased from 52% to 99.4% at the maximum. Possible advantages by the application of Sc(2)O(3) and Y(2)O(3) instead of SiO for antireflection coatings on GaAs laser surfaces are discussed.

Dielectric Properties of Y2O3 Thin Films Prepared by Vacuum Evaporation

The dielectric films formed by evaporating Y2O3 in vacuum have been identified with sesquioxide by infrared transmission, electron and X-ray diffraction studies. Thin film capacitors using this dielectric material exhibit excellent electric stability in high termperature and can be reproduced easily in a closed-cycle process with electron beam equipment. The dielectric constant is 13 and dissipation factor, tan δ, is 0.003 at room temperature with a breakdown field strength of 3×106 V/cm. The temperature coefficient of Y2O3 film capacitor is about 300 ppm/°C.