ZrO2 Gel Films Research Articles

X ray photoelectron spectroscopy (XPS) analysis of Photosensitive ZrO2 array

Based on organic zirconium source as the starting material, by adding chemical modifiers which are made up with photosensitive ZrO2 sol. A uniformed ZrO2 array dot was fabricated with a mean diameter of around 800 nm. By using UV-vis spectra and X-ray photoelectron spectroscopy analysis method, studies the photosensitive ZrO2 gel film of photochemical reaction process and the photosensitive mechanism, to determine the zirconium atom centered chelate structure, reaction formed by metal chelate Zr atom for the center, and to establish the molecular model of the chelate. And studied the ultraviolet light in the process of the variation of the XPS spectra, Zr3d5/2 to 184.9 eV corresponding to the binding energy of the as the combination of state peak gradually reduce; By combining with the status of Zr-O peak gradually increase; The strength of the peak is gradually decline. This suggests that in the process of ultraviolet light photo chemical reaction happened. This study is of great significance to the micro fabrication of ZrO2 array not only to the memory devices but also to the optical devices.

Ultraviolet-assisted direct patterning and low-temperature formation of flexible ZrO2 resistive switching arrays on PET/ITO substrates

We demonstrate a low-cost and facile photochemical solution method to prepare the ZrO2 resistive switching arrays as memristive units on flexible PET/ITO substrates. ZrO2 solution sensitive to UV light of 337 nm was synthesized using zirconium n-butyl alcohol as the precursor, and benzoylacetone as the complexing agent. After the dip-coated ZrO2 gel films were irradiated through a mask under the UV lamp (with wavelength of 325–365 nm) at room temperature and rinsed in ethanol, the ZrO2 gel arrays were obtained on PET/ITO substrates. Subsequently, the ZrO2 gel arrays were irradiated by deep UV light of 254 and 185 nm at 150 °C, resulting in the amorphous ZrO2 memristive micro-arrays. The ZrO2 units on flexible PET/ITO substrates exhibited excellent memristive properties. A high ratio of 104 of on-state and off-state resistance was obtained. The resistive switching behavior of the flexible device remained stable after being bent for 103 times. The device showed stable flexibility up to a minimum bending diameter of 1.25 cm.

Low-cost micro-lens arrays fabricated by photosensitive sol–gel and multi-beam laser interference

In this paper, we introduce a low-cost approach for fabricating micro-lens arrays that is based on photosensitive sol–gel and multi-beam laser interference. UV photosensitive ZrO2 gel films are prepared with Zr(O(CH2)3CH3)4 and BzAcH as the precursor and chemical modifier, respectively. With UV laser irradiation via different dose, nonlinear photodecomposition occurs in this film. Large scale 2D micro lens arrays with the sizes of 830nm×830nm and 280nm×280nm are fabricated by four-beam laser interference. The surface profile modeling shows that the micro lens is plano convex lens, and the effective focal lengths are 812.0nm and 317.6nm, respectively.

Bio-Detection of Dipeptides by the ZrO<SUB>2</SUB>/PVA/Cyt.<I>c</I> Multilayer Film

The adsorption mechanism of dipeptides namely Gly-Glu, Asp-Glu with protein layer was successfully examined on cytochrome c (Cyt.c) surface probing by fluorescent dye molecule. Molecularly thin Cyt.c layer was immobilized on poly(vinyl alcohol) (PVA) coated zirconium oxide (ZrO2) gel films by electrostatic interaction. Denaturation of Cyt.c was minimized on sol-gel derived ZrO2-gel film by PVA. The conformation of immobilized protein was verified by FTIR-ATR measurements. The fluorescent dye molecule was easily bound on the Cyt.c layer. The dye adsorbed protein thin film was soaked in two different dipeptides solution with various concentrations. The adsorption of dipeptides on Cyt.c thin film and consequent desorption of fluorescent dye from Cyt.c layer in dipeptide solutions was monitored by UV-vis absorption, fluorescence spectroscopy and quartz crystal microbalance method. The ion exchange mechanism on protein surface between fluorescent dye and dipeptides is thought to be responsible for dye desorption and formation of relatively strong electrostatic bonding between dipeptides with protein. The adsorption behavior curve of dipeptides was analyzed by Hill equation. The number of functional group together with size of dipeptides play an important role for different adsorption parameters obtained from this model.

Synthesis of ZrN Thin Film by a New Carbothermal Nitridation Method of Sol-Gel Derived ZrO2

ZrO2 gel film was prepared by spin-coating of Zr sol from Zr-n-propoxide, n-propanol, acetylacetone, water and nitric acid, on various substrates such as polycrystalline Al2O3, and single crystals of Al2O3, SrTiO3, 8 mol% Y2O3 doped ZrO2 (YSZ) and MgO. The dried-gel film on Al2O3 substrate was transformed to cubic ZrN single phase with bright gold-color by a new carbothermal nitridation method, in which the thin film was covered with a porous graphite crucible to realize a strong reducing atmosphere was fired in flowing nitrogen gas at a fairly high temperatures above 1673 K. The ZrN thin film thus obtained was characterized by means of X-ray diffractometry (XRD), scanning electron microscopy (SEM) observation, reflection spectra.

Preparation of New Photosensitive ZrO2Gel Films Using Hydroxyl-Substituted Aromatic Ketones as Chemical Modification Reagents and their Patterning

ZrO2 gel films were prepared from zirconium tetra-n-butoxide chemically modified with one of hydroxyl-substituted aromatic ketones and 1′-hydroxy-2′-acetonaphthone, by the sol-gel method. The obtained gel film showed an absorption band, characteristic of the π-π* transition of chelate ring, at around 410 nm. The band was shifted to longer wavelength region than those for the gel films using β-diketones. The reason is thought that the hydroxyl-substituted aromatic ketone has π-electron system to form the condensed chelate ring. The absorption band associated with the chelate ring gradually decreased in intensity with UV-irradiation using a high pressure mercury lamp. This indicates that the chelate ring dissociates by the UV-irradiation and that the gel film exhibits photosensitivity. Utilizing the photosensitivity, fine patterns (about 1 μm) could be fabricated by UV-irradiation through a mask and leaching.

Fabrication of Two-Dimensional Gratings Using Photosensitive Gel Films and Their Characterization

Two-dimensional (2D) surface-relief gratings have been fabricated by the two-beam interference method on photosensitive gel films, which are derived from chemically modified metal-alkoxides, and characterized with respect to surface morphology and antireflection effect. Photosensitive ZrO2 gel film was deposited on a silica glass substrate using the sol that was prepared from Zr-tetrabutoxide chemically modified with benzoylacetone. The gel film was exposed to two-beam interference fringe (1.0 μm period) of He-Cd laser and then rotated by 90° in its own plane, followed by an additional exposure. Leaching of the gel film with ethanol gave lattice or island types of 2D-gratings depending on the dose of laser irradiation. The morphology of the gratings changed with irradiation time of laser, leaching conditions and so on. The formation of 2D-grating of island type on a silica glass substrate substantially reduced the reflection at its surface in a wavelength range of 1.3 to 2.6 μm.

Improvement of Spectral Sensitivities for Photosennsitive ZrO2 Gel Films

Improvement of Spectral Sensitivities for Photosennsitive ZrO2 Gel Films

Low-Reflection Microstructure Formed by Sol–Gel Process

Low-reflection microstructures were formed by the use of a two-beam interference patterning on a photosensitive ZrO2 gel film. Gel films coated on SiO2 glass were exposed to an interference fringe of 325 nm He–Cd laser beams. The substrate was rotated by 90° between the first and second irradiation steps. Island and lattice type periodic two-dimensional structures with a pitch of 1 µm were formed after the irradiation followed by leaching with ethanol. Reflectance of 0.1% for an optically polished SiO2 surface was attained at around a 1750 nm wavelength by the formation of an island-type microstructure. The transmission spectrum was successfully simulated by the rigorous coupled wave analysis. The heat treatment of the microstructure up to a temperature of 200°C was possible in an ambient atmosphere without a conspicuous increase in reflectance.

Selective Coloration of Photosensitive ZrO2 Gel Films.

A Selective coloration process has been newly developed utilizing photosensitive gel films derived from metal-alkoxides chemically modified with β-diketones. Photosensitive ZrO2 gel films modified with acetylacetone were irradiated with UV-light through a mask and then SiO2 gel films containing various dyes were deposited on them. Rinsing these bilayers with water produced positive color patterns of the mask used. The dye-containing SiO2 gel film on the unirradiated part of the ZrO2 gel film remained, while that on the irradiated part was removed upon rinsing. This phenomenon can be ascribed to the difference in interaction between SiO2 and ZrO2 gel films in irradiated and unirradiated parts.

Diffraction gratings of photosensitive ZrO_2 gel films fabricated with the two-ultraviolet-beam interference method

Photosensitive ZrO(2) gel films were patterned with a two-beam interference method by use of a 325-nm-wavelength He-Cd laser for the first time to our knowledge. The ZrO(2) gel films were prepared from Zr(O-n-C(4)H(9))(4) chemically modified with benzoylacetone. We fabricated uniform gratings with a 0.5-microm period on Si or SiO(2) substrates by etching the gel films in ethyl alcohol after UV irradiation. A maximum diffraction efficiency of 28% was attained with the grating fabricated on Si substrate under a Littrow mounting condition by use of a 633-nm-wavelength He-Ne laser. Blazed gratings could also be fabricated.

Characteristics of Diffraction Gratings Fabricated by the Two-Beam Interference Method Using Photosensitive Hybrid Gel Films

Diffraction gratings of arbitrary periods have been fabricated by the two-beam interference method using photosensitive ZrO2 gel films and characterized. The ZrO2 gel films were formed on Si or silica glass substrates from sols that were derived from Zr-butoxide modified chemically with benzoylacetone. The gel films were irradiated with two interference beams from a He-Cd laser (325 nm) and then leached in ethyl alcohol. The above process gave uniform surface-relief gratings of periods ranging from 1.0 to 0.5 μm, depending on the incidence angle of the interference beams. The diffraction efficiency, measured in the Littrow configuration using a He-Ne laser (633 nm), showed polarization dependence for the grating of 0.5 μm period but not for the gratings of 1.0 μm period. The maximum diffraction efficiency was 18% for the grating of 1.0 μm period and 28% for that of 0.5 μm period in the reflection mode. The present study has proved that the photosensitive gel films are versatile in fabrication of optical devices.

Synthesis of Highly Oriented Zirconia Film by Sol-Gel Method

ZrO2 and Y2O3-doped ZrO2 gel films were obtained by spin-coating of a sol from Zr-n-propoxide, n-propanol, acetylacetone, water, and nitric acid on a silica glass as a substrate. The dried-gel films crystallized to monoclinic, tetragonal, cubic and their mixed phases, depending on the firing temperature and Y2O3 content. The ZrO2 films with highly preferential orientation were successfully obtained from a solution containing a large amount of n-propanol. The highly oriented ZrO2 film was found to have high transparency compared with the non-oriented films.

Effects of UV-irradiation on the formation of oxide thin films from chemically modified metal-alkoxides

The effects of UV-irradiation on the properties of ZrO2 and TiO2 gel films prepared from corresponding metal-butoxides modified with acetylacetone (AcAc) or benzoylacetone (BzAc) have been studied. It was found that the chelate bonds of β-diketones remaining in the gel films were dissociated by the UV-irradiation. The UV-irradiation also changed the properties of the gel films such as solubility; the solubility in acidic solutions was decreased for ZrO2 gel films modified with AcAc and TiO2 gel films modified with BzAc became insoluble in alcohol. Based on these findings, a new fine-patterning process has been established, which enables us to make fine-patterns of ZrO2 and TiO2 films on a variety of substrates.