Yttrium Oxide Thin Films Research Articles

Growth and Characterization of Y 2 O 3 : Tm Thin‐Film Blue‐Emitting Phosphor

Thulium‐doped yttrium oxide thin films were grown on amorphous quartz and indium‐tin oxide glass substrates employing an electron‐beam evaporation technique. Structural characterization was carried out at various substrate and annealing temperatures. was evaluated as a blue‐emitting phosphor for field emission display based on its cathode‐luminescent spectra, chromaticity, and brightness at low‐voltage excitation (<5 keV). Sharp emission was observed from thulium at 454 nm. The cathode luminance of the thin films was assessed with respect to substrates and annealing temperatures. The result shows that grown on indium‐tin oxide glass at 500°C followed with annealing at 800°C has better luminescent properties as compared to amorphous quartz. © 1999 The Electrochemical Society. All rights reserved.

Modeling of Cathodoluminescence and Photoluminescence Properties of Pulsed Laser-Deposited Europium-Activated Yttrium Oxide thin Film Phosphors

ABSTRACTEuropium-activated yttrium oxide (Eu:Y2O3) thin films were deposited on (100) silicon and (0001) sapphire substrates using 248 nm KrF pulsed laser. To investigate the effect of the Eu:Y2O3 film roughness on cathodoluminescence (CL) and photoluminescence (PL) properties, the substrate surfaces with various roughnesses were used. The roughness was found to play an important role in determining CL and PL brightness of the Eu:Y2O3 films. The improvement in brightness by increasing the film roughness is due to increase in total portion of light that escapes from the surface of the phosphor film. A model has been proposed which supports strongly this explanation. Our results show that depositions with slower growth rate and lower laser energy are more important parameters than increasing the roughness to improve CL brightness of the Eu:Y2O3 thin film phosphors.

Modeling of Cathodoluminescence and Photoluminescence Properties of Pulsed Laser-Deposited Europium-Activated Yttrium Oxide Thin Film Phosphors

ABSTRACTEuropium-activated yttrium oxide (Eu:Y2O3) thin films were deposited on (100) silicon and (0001) sapphire substrates using 248 nm KrF pulsed laser. To investigate the effect of the Eu:Y2O3 film roughness on cathodoluminescence (CL) and photoluminescence (PL) properties, the substrate surfaces with various roughnesses were used. The roughness was found to play an important role in determining CL and PL brightness of the Eu:Y2O3 films. The improvement in brightness by increasing the film roughness is due to increase in total portion of light that escapes from the surface of the phosphor film. A model has been proposed which supports strongly this explanation. Our results show that depositions with slower growth rate and lower laser energy are more important parameters than increasing the roughness to improve CL brightness of the Eu:Y2O3 thin film phosphors.

Luminescent Characteristics of Pulsed Laser Deposited Epitaxial Eu-Doped Y2O3 Films

AbstractThe growth, structural and cathodoluminescent (CL) properties of europium activated yttrium oxide (Eu:Y2O3) thin films are reported. The Eu:Y2O3 films were grown in-situ using a pulsed laser deposition technique. Our results show that Eu:Y2O3 films can grow epitaxially on (100) LaAlO3 substrates under optimized deposition parameters. The epitaxial growth of Eu:Y2O3 films on LaAlO3, which has a lattice mismatch of ∼ 60 %, is explained by matching of the atom positions in the lattices of the film and the substrate after a rotation. CL data from these films are consistent with highly crystalline Eu:Y2O3 films with an intense CL emission at 611 nm.

Catalyst-Enhanced Chemical Vapor Deposition of Yttrium Oxide

High-quality yttrium oxide thin films can be prepared from [Y(thd)3] (1, thd = 2,2,6,6-tetramethyl-3,5-heptanedionato) under mild conditions by the catalyst-enhanced chemical vapor deposition technique using oxygen as carrier gas. Several palladium compounds, such as [Pd(acac)2] (acac = 2,4-pentadionato), [Pd(η3-C3H5)(η5-C5H5)] (C3H5 = allyl), and [Pd(η3-C4H7)(acac)] (C4H7 = 2-methylallyl), have been used as catalyst precursors. The films of yttria have open, amorphous structures, as characterized using XPS, SEM, EDX, and XRD techniques. The volatile products of the chemical vapor deposition reactions are analyzed and give evidence for the catalytic chemical vapor deposition.

Synthesis of yttrium oxide thin films with and without the use of organic self-assembled monolayers

Thin Y-containing films have been deposited at 80 °C from aqueous solutions of YNO3⋅5H2O and urea on bare single crystal Si wafers, and on Si wafers coated with sulfonate-functionalized organic self-assembled monolayers. The as-deposited films are believed to be an amorphous yttrium basic carbonate and can be completely transformed at 600 °C in air to crystalline Y2O3. Capacitance–voltage measurements on these films showed good dielectric properties, with a relative permitivity of 18, more than a factor of four higher than that of SiO2.

Microstructural and Photoluminescence Studies on Europium Doped Yttrium Oxide Films Synthesized by Metallorganic Vapor Deposition

ABSTRACTThe microstructural and luminescence properties of europium doped yttrium oxide (Y2O3:Eu) thin films deposited by metallorganic chemical vapor deposition are presented in this work. It was found that surface morphology, crystallinity and photoluminescent emission properties are strongly dependent on substrate temperature during deposition. The depositions were carried out in a stainless steel chamber using yttrium and europium 2,2,6,6,-tetramethyl–3,5-heptanedionates as volatile precursors and O2 as the reactant gas. Post-annealing increased the crystallite size and decreased the lattice parameter, resulting in an increased photoluminescent emission intensity.

Properties of Yttrium Oxide Thin Films on Silicon (100) Prepared by Evaporation of Yttrium in Atomic Oxygen

AbstractThin layers of Y2O3 have been prepared on silicon (100) by an activated reactive evaporation process involving evaporation of metal Y in an atomic oxygen plasma. The presence of the oxygen plasma was found to be crucial for the formation of homogeneous Y2O3 films on Si. The formation of Y2O3 films on Si (100) at different substrate temperatures was investigated. X-ray diffraction analysis showed that Y2O3 films formed between 300 °C and 650 °C were (111) textured while Y2O3 prepared at lower substrate temperatures (80 °C) exhibited mixed orientations. Rutherford backscattering spectrometry indicated that films were stoichiometric. No pronounced channeling was observed in films grown at 350 °C, suggesting polycrystalline film structures. Atomic force microscopy revealed very smooth surface morphologies with average surface roughness &lt; 20 Å for films 700 Å thick deposited at 350 °C. Secondary ion mass spectroscopy indicated the abundance of intermediate layers in the film-substrate interface.

Growth and dielectric characterization of yttrium oxide thin films deposited on Si by r.f.-magnetron sputtering

Thin films of Y 2O 3 have been deposited by r.f.-magnetron sputtering onto 100 mm diameter n-type single crystal Si wafers. The growth conditions are discussed including an optical interferometric technique for in-situ thickness monitoring. The dielectric properties of films deposited at 60 °C, 100 °C and 190 °C are measured, with optimum values of the relative dielectric constant and breakdown strength determined as ϵ r = 16 and E bd = 3.85 MV cm -1 respectively. Deposition was uniform with respect to film thickness over 50 cm 2 (±5%), and the refractive index of the Y 2O 3 was determined as n = 1.911

Electrical behaviour of electron-beam-evaporated yttrium oxide thin films on silicon

The electrical properties of electron-beam-deposited Y 2O 3 film interfaced with Si(100) have been investigated. The thickness-dependent effective dielectric constant of the Y 2O 3 film increases to 18–27 and bulk trapped charge density decreases to (10−4) × 10 11 cm -2 after oxygen annealing at approximately 800 K temperatures. These changes are attributed to annealing out of defects and improvement in the stoichiometry of the Y 2O 3 film by oxygen intake. In as-deposited Y 2O 3 (400 Å) films, the leakage current density is about 7 × 10 -8 A cm -2 at 0.1 MV cm -1. Moderate initial annealing causes it to increase as a result of localized field regions caused by structural changes at macroscopic defects in the polycrystalline Y 2O 3 film. A decrease later to 4 × 10 -9 A cm -2 on high temperature annealing is caused by reduction in defects and growth of amorphous SiO 2 film at the interface. The current transport across the Y 2O 3 film is by a Poole-Frankel emission process. High dielectric constant, low trap density and well-behaved capacitance-voltage characteristics exhibiting metal-oxide-semiconductor (MOS) action suggest possible applications of Y 2O 3 films as high density MOS capacitors and gate dielectric in very-large-scale integration technology.

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.

Structural characterization of yttrium oxide thin films using transmission electron microscopy

Caracterisation structurale des couches en fonction de leur epaisseur et relation entre la structure et les proprietes optiques

Radio frequency dielectric dissipation measurements on yttrium oxide thin films

The dielectric dissipation factor (tan δ) of evaporated thin film Al-Y 2-O 3-Au capacitors has been measured in the frequency range 1 kHz-40 MHz. The yttrium oxide films (≈ 5000 Å) were fabricated by the direct electron-beam evaporation of 99.9% Y 2O 3 powder. The geometry of these capacitors (≈ 40 pF) deposited on alumina substrates provided large contact pads for direct attachment to the measuring bridges. Lead inductance was minimal while lead and contact resistance was less than 0.2 ω. Tan δ measurements were made at 20°C with a capacitance bridge, a Wayne Kerr bridge and a Q-meter at appropriate frequencies. At 1 kHz, tan δ values of various specimens varied from 0.004–0.009. These values decreased rapidly with increasingly frequency, however, to a resistance-corrected constant value tan δ≦0.004 over the range 100 kHz-40 MHz.

Some dielectric properties of electron-beam evaporated yttrium oxide thin films

Thin films of yttrium oxide have been fabricated by the direct electron-beam evaporation, in an oxygen atmosphere, of 99.9% yttrium oxide powder. Such films, ranging in thickness from about 2000 Å to 15,000 Å, have been observed to be quite stable and free of pinholes over areas as large as 0.5 in. × 0.5 in. At 1000 Hz and 25 °C the lowest value of dielectric dissipation factor (tan δ) obtained was 0.00255, decreasing to a value of 0.0024 at 100 kHz. Bridge measurements on such films forming capacitors of the type AlY 2O 3Au further yielded an average dielectric permittivity value ε′ = 13.5 ± 1.5 and a temperature coefficient of capacitance of + 320 p.p.m./°C. Typical breakdown field strengths were in the order of 2.8 × 10 6 volt/cm for such capacitors as large as 0.065 μF, whilst the measured resistivity of the dielectric was estimated to be > 2 × 10 14 Ω cm .