YMnO3 Thin Films Research Articles

Origin of Leakage Current of YMnO3 Thin Films Prepared by the Sol-Gel Method

AbstractThe preparation conditions of YMnO3 thin films by the sol-gel method using yttrium alkoxide were optimized to decrease the leakage current of the films. The leakage current of the films was decreased due to the dense microstructure of the films. Moreover, the heat treatment in hydrogen atmosphere and the zirconium doping resulted in a further decrease of the leakage current. The heat treatment in hydrogen atmosphere and the zirconium doping were effective in the decrease of carriers originating in the valence fluctuation of the Mn ions in YMnO3

Epitaxial Growth of Ferroelectric YMnO3 Thin Films on Si (111) Substrates by Molecular Beam Epitaxy

Ferroelectric YMnO3 thin films are grown on Si (111) substrates using Y2O3 buffer layers by molecular beam epitaxy (MBE). In situ reflection high-energy electron diffraction (RHEED) analyses show that both Y2O3 and YMnO3 films are epitaxially grown on Si substrates. X-ray rocking curve measurements also show that the best full-width at half maximum (FWHM) values for Y2O3 and YMnO3 films are 0.4° and 1.5°, respectively. Concerning the electrical properties, capacitance–voltage (C–V) characteristics of Al/YMnO3/Y2O3/Si structures indicate the ferroelectric properties of YMnO3 films with a memory window of 0.3 V.

Preparation of ferroelectric YMnO3 thin films for nonvolatile memory devices by metalorganic chemical vapor deposition

Ferroelectric YMnO3 thin films were successfully prepared on Si(111) and Pt/Ti/SiO2/Si substrates using a hot-wall type metalorganic chemical vapor deposition. When Y/Mn ratio was 0.98, the remanent polarization, Pr, and the coercive field, Ec, of YMnO3 films deposited Pt/Ti/Si/SiO2/Si were 2.6 μ C/cm2 and 36.1 kV/cm at an applied voltage of 5V, respectively. The dielectric constant and the dissipation factor at 1MHz were about 16.6 and 0.046, respectively. The leakage current density of the 360 nm thick YMnO3 film was 4.7 × 10-6 A/cm2 at 40 kV/cm.

Ferroelectric characterization of highly (0001)-oriented YMnO3 thin films grown by chemical solution deposition

Highly (0001)-oriented thin films of YMnO3 were grown directly on Si substrates by chemical solution deposition. The crystallinity of the films was investigated by using x-ray diffraction: θ–2θ scan, rocking curve, and pole figure. Analysis of the x-ray photoelectron spectroscopy data and Rutherford backscattering spectroscopy spectrum showed that the films had a single phase of stoichiometric YMnO3. The ferroelectric properties of YMnO3 were investigated by measuring the temperature dependence of the capacitance–voltage characteristics in the metal/ferroelectric/semiconductor structure. Screening of the ferroelectricity of YMnO3 thin film at room temperature was discussed in conjunction with the charge effects.

Microstructure and Dielectric Properties of YMnO3 Thin Films Prepared by Dip‐Coating

YMnO3 thin films with Y/Mn ratios from 1.00/1.05 to 1.00/0.90 were prepared by dip‐coating from solution, in which starting materials were refluxed, and the effects of the Y/Mn ratio on the structure and dielectric properties of YMnO3 thin films were investigated. XRD measurements indicated that the films with the Y/Mn ratios in this study were a single phase of polycrystalline YMnO3. The lattice constants along the a‐axis and c‐axis lengthened with an increase in the Y/Mn ratio. FE‐SEM micrographs of the films showed that the surface of the films became smoother and denser with an increase in the Y/Mn ratio. YMnO3 thin films with good dielectric properties were obtained with an Y/Mn ratio of 1.00/0.90, which gave the smoothest and densest microstructure and the smallest leakage current.

MBE Growth of Ferroelectric YMnO3 Thin Films on Si(111) Using Y2O3 Buffer Layers

AbstractA ferroelectric YMnO3 thin films are grown on Si (111) substrates using Y2O3 buffer layers by molecular beam epitaxy (MBE). In-situ reflection high-energy electron diffraction (RHEED) analyses show that both Y2O3 and YMnO3 films are epitaxially grown on Si substrates. X-ray rocking curve measurements also show that the best FWHM (full width at half maximum) values for Y2O3 and YMnO3 films are 0.40° and 0.8°, respectively. C-V characteristics of Al/YMnO3/Y2O3/Si structures indicate the ferroelectric properties of YMnO3 films with a memory window of 0.7V.

Fabrication of YMnO3 Thin Films on Si Substrates by a Pulsed Laser Deposition Method

We have proposed ReMnO3 (Re: Rare earth elements) films for metal-ferroelectric-semiconductor field effect transistor-(MFSFET) type ferroelectric random access memories (Ferroelectric RAMs). For this kind of application, since ReMnO3 films must be fabricated directly on Si substrates, this wrote focuses on the fabrication of YMnO3 films on Si substrates with and without buffer layers. Although only amorphous YMnO3 films are obtained without buffer layers, crystalline films are obtained using Y–Mn–O buffer layers deposited without introducing oxygen. YMnO3 films can be epitaxially grown on the top of epitaxial Y2O3 on (111)Si. For both crystalline YMnO3 films, although hysteresis behavior in D-E measurement is observed, remanent polarizations are quite small. The role of buffer layers on the thin film growth of YMnO3 on (111)Si is discussed.

Oxygen reduction at (La0.5Sr0.5) yMnO3 thin films/YSZ interface

(La0.5Sr0.5) yMnO3 thin film electrodes were deposited onto yttria stabilized zirconia electrolyte by means of an ultrasonic spray technique. Cathodic polarization curves were drawn at 800 and 900°C in air. Results could not be explained either by a transfer or by a diffusion limited process.