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1.
Tae Eun Hong Tae‐Ho Kim Jae‐Hun Jung Soo‐Hyun Kim Hoon Kim 《Journal of the American Ceramic Society》2014,97(1):127-134
TaCx films were deposited by atomic layer deposition (ALD) using tris (neopentyl) tantalum dichloride, (Ta[CH2C(CH3)3]3Cl2) and H2 plasma as the precursor and reactant, respectively, at substrate temperatures ranging from 200°C to 400°C. The ALD–TaCx films with the formation of nanocrystalline structures and a rock‐salt phase were confirmed by X‐ray and electron diffraction. The ALD temperature window was found to be 225°C–300°C with a growth rate of ~0.11 nm per cycle. The resistivity of the ALD–TaCx films was dependent on the microstructural features, such as the grain size and crystallinity, as well as their composition (C/Ta ratio), and the presence of impurities in the films, which could be controlled by varying the deposition parameters, such as the deposition temperature and reactant pulse conditions. With increasing deposition temperature and reactant pulse time, Ta‐rich films with a low Cl impurity concentration and larger grain size were obtained. The film with a resistivity less than 400 μΩ cm was obtained at 300°C, which was within the ALD temperature window, by optimizing the H2 plasma pulse time. The step coverage of the film deposited at 300°C was approximately 100% over the trench structure (top opening width of 25 nm) with an aspect ratio of ~4.5. The performance of the ALD–TaCx films deposited under the optimized conditions was evaluated as a diffusion barrier for the Cu interconnects. The structure of Cu (100 nm)/ALD–TaCx (5 nm)/ Si was stable without the formation of copper silicide after annealing at 600°C for 30 min. 相似文献
2.
Woo‐Hee Kim Min‐Kyu Kim Il‐Kwon Oh Wan Joo Maeng Taehoon Cheon Soo‐Hyun Kim Atif Noori David Thompson Schubert Chu Hyungjun Kim 《Journal of the American Ceramic Society》2014,97(4):1164-1169
Films of CeO2 were deposited by atomic layer deposition (ALD) using a Ce(mmp)4 [mmp = 1‐methoxy‐2‐methyl‐2‐propanolate] precursor and H2O reactant. The growth characteristics and film properties of ALD CeO2 were investigated. The ALD CeO2 process produced highly pure, stoichiometric films with polycrystalline cubic phases. Using the ALD CeO2 process, the effects of Ce doping into an HfO2 gate dielectric were systematically investigated. Regardless of Ce/(Ce + Hf) composition, all ALD CexHf1?xO2 films exhibited constant growth rates of approximately 1.3 Å/cycle, which is essentially identical to the ALD HfO2 growth rates. After high‐temperature vacuum annealing at 900°C, it was verified, based on X‐ray diffraction and high‐resolution cross‐sectional transmission electron microscopy results, that all samples with various Ce/(Ce + Hf) compositions were transformed from nanocrystalline to stabilized cubic or tetragonal HfO2 phases. In addition, the dielectric constant of the CexHf1?xO2 films significantly increased, depending on the Ce doping content. The maximum dielectric constant value was found to be nearly 39 for the Ce/(Ce + Hf) concentration of ~11%. 相似文献
3.
Olha Mashtalir Murat Kurtoglu Sergey Pogulay Alexey Gogotsi Michael Naguib Yury Gogotsi 《International Journal of Applied Ceramic Technology》2013,10(1):26-32
This paper reports on the structure, mechanical, and photocatalytic properties of titanium dioxide (TiO2) and tungsten oxide (WO3) films on a brass substrate. TiO2 and WO3 films have been successfully deposited on brass by a simple sol‐gel dip‐coating method and it has been shown that, while both films possess photocatalytic properties, WO3 films were superior to TiO2. Higher surface area and rod‐like morphology of WO3 films might have contributed to their higher photocatalytic activity. Nanoindentation results have shown that both films attach well to the substrate and possess good mechanical properties. 相似文献
4.
E.J. McLeod 《Electrochimica acta》2005,51(4):684-693
WOx was synthesised from W(OC2H5)6 by two different methods using the sol-gel (SG) approach, Type 1 using ethanol as the solvent, while Type 2 was water-based. Films and powders made from these sols were subjected to analysis by cyclic voltammetry (CV), powder X-ray diffraction (XRD), and scanning electron microscopy (SEM). Sweep rate experiments revealed that compared to Type 1 films, Type 2 films have a significantly greater number of electroactive WOx sites, and that a smaller proportion of the total active sites are surface sites, indicative of a higher film porosity (consistent with the SEM results). XRD analysis showed that both Type 1 and Type 2 WOx were poorly crystallised. However, the patterns for the two WOx types were distinctly different, with Type 2 WOx giving a more well-defined pattern. WOx sols were also successfully combined with a pre-formed Pt sol. Unlike Pt-only catalysts, methanol oxidation currents on Type 2 WOx/Pt films did not decay rapidly with potential cycling, indicating the occurrence of co-catalytic behaviour, while Type 1 films were not very active, overall. The low resistance exhibited by the WOx component makes it suitable as an ionically and electronically conducting support for direct methanol fuel cell electrocatalysts. 相似文献
5.
《Ceramics International》2021,47(20):28770-28777
Atomic layer deposition (ALD) is a thin-film fabrication method that can be used to deposit films with precise thickness controllability and uniformity. The low deposition temperature of ALD, however, often interrupts the facile crystallization of films, resulting in inferior optical and electrical properties. In this study, the extremely localized crystallization of TiO2 thin films was demonstrated by per-cycle plasma treatment during the plasma-enhanced ALD process. By layering crystalline and amorphous films, a phase-gradient TiO2 film with precisely modulated optical and electrical properties was fabricated. Moreover, the ratio between the amorphous and crystalline layer thicknesses for a high dielectric constant and low leakage current density was optimized. 相似文献
6.
Ozone (O3) was employed as an oxygen source for the atomic layer deposition (ALD) of titanium dioxide (TiO2) based on tetrakis-dimethyl-amido titanium (TDMAT). The effects of deposition temperature and O3 feeding time on the film growth kinetics and physical/chemical properties of the TiO2 films were investigated. Film growth was possible at as low as 75 °C, and the growth rate (thickness/cycles) of TiO2 was minimally affected by varying the temperatures at 150–225 °C. Moreover, saturated growth behavior on the O3 feeding time was observed at longer than 0.5 s. Higher temperatures tend to provide films with lower levels of carbon impurities. The film thickness increased linearly as the number of cycles increased. With thicker films and at higher deposition temperatures, surface roughening tended to increase. The as-deposited films were amorphous regardless of the substrate temperatures and there was no change of crystal phase even after annealing at temperatures of 400–600 °C. The films deposited in 0.5 mm holes with an aspect ratio of 3: 1 showed an excellent conformality. 相似文献
7.
《Ceramics International》2022,48(3):3280-3286
Orthorhombic HfxZr1-xO2 (HZO) is a promising ferroelectric material for realizing ferroelectric devices in the modern semiconductor industry because of its excellent CMOS compatibility and scalability. Atomic layer deposition (ALD) facilitates the growth of robust ferroelectric HZO films that can be used in nanoelectronic devices. Herein, we provide a comprehensive understanding of the effects of the oxygen source, either H2O or O3, on the properties of ALD-grown HZO films. Although the growth per cycle promoted by ALD does not change with the type of oxygen source, the impurity content of the HZO film grown with H2O are higher than that with O3. The low impurity content of the HZO film grown with O3 results in low leakage current. The ALD process with O3 further suppresses the emergence of the nonferroelectric monoclinic phase in the ferroelectric orthorhombic HZO matrix. Consequently, the HZO film grown with O3 exhibits a small coercive field for ferroelectric domain switching and high electrical reliability. This study demonstrates that O3 is more favorable for growing high-quality HZO films via ALD by using metal precursors comprising tetrakis(ethylmethylamino) ligands. 相似文献
8.
TiO2/WOx nanotubes have unique photo-energy retention properties that have gathered scientific interest. Herein, we report the synthesis, morphological characterization, and the electrochemical characterization of TiO2/WOx nanotubes compared with pure TiO2 nanotubes, prepared by anodization technique. Significant structural differences were not observed in TiO2/WOx nanotubes as observed by using scanning electron microscopy and transmission electron microscopy. The charge transfer resistance of TiO2/WOx before and after photo irradiation determined by using electrochemical impedance spectroscopy proves the inherent energy retention property which was not observed in pure TiO2 nanotubes. 相似文献
9.
The structure of vertically aligned carbon nanotubes (CNTs) severely depends on the properties of pre-prepared catalyst films.
Aiming for the preparation of precisely controlled catalyst film, atomic layer deposition (ALD) was employed to deposit uniform
Fe2O3 film for the growth of CNT arrays on planar substrate surfaces as well as the curved ones. Iron acetylacetonate and ozone
were introduced into the reactor alternately as precursors to realize the formation of catalyst films. By varying the deposition
cycles, uniform and smooth Fe2O3 catalyst films with different thicknesses were obtained on Si/SiO2 substrate, which supported the growth of highly oriented few-walled CNT arrays. Utilizing the advantage of ALD process in
coating non-planar surfaces, uniform catalyst films can also be successfully deposited onto quartz fibers. Aligned few-walled
CNTs can be grafted on the quartz fibers, and they self-organized into a leaf-shaped structure due to the curved surface morphology.
The growth of aligned CNTs on non-planar surfaces holds promise in constructing hierarchical CNT architectures in future. 相似文献
10.
We fabricated a new organic-inorganic hybrid superlattice film using molecular layer deposition [MLD] combined with atomic
layer deposition [ALD]. In the molecular layer deposition process, polydiacetylene [PDA] layers were grown by repeated sequential
adsorption of titanium tetrachloride and 2,4-hexadiyne-1,6-diol with ultraviolet polymerization under a substrate temperature
of 100°C. Titanium oxide [TiO2] inorganic layers were deposited at the same temperatures with alternating surface-saturating reactions of titanium tetrachloride
and water. Ellipsometry analysis showed a self-limiting surface reaction process and linear growth of the nanohybrid films.
The transmission electron microscopy analysis of the titanium oxide cross-linked polydiacetylene [TiOPDA]-TiO2 thin films confirmed the MLD growth rate and showed that the films are amorphous superlattices. Composition and polymerization
of the films were confirmed by infrared spectroscopy. The TiOPDA-TiO2 nanohybrid superlattice films exhibited good thermal and mechanical stabilities. 相似文献
11.
Björn Wickman Maria Wesselmark Carina Lagergren Göran Lindbergh 《Electrochimica acta》2011,56(25):9496
Thin films of WOx and Pt on WOx were evaporated onto the microporous layer of a gas diffusion layer (GDL) and served as model electrodes in the polymer electrolyte fuel cell (PEFC) as well as in liquid electrolyte measurements. In order to study the effects of introducing WOx in PEFC electrodes, precise amounts of WOx (films ranging from 0 to 40 nm) with or without a top layer of Pt (3 nm) were prepared. The structure of the thin-film model electrodes was characterized by scanning electron microscopy and X-ray photoelectron spectroscopy prior to the electrochemical investigations. The electrodes were analyzed by cyclic voltammetry and the electrocatalytic activity for hydrogen oxidation reaction (HOR) and CO oxidation was examined. The impact of Nafion in the electrode structure was examined by comparing samples with and without Nafion solution sprayed onto the electrode. Fuel cell measurements showed an increased amount of hydrogen tungsten bronzes formed for increasing WOx thicknesses and that Pt affected the intercalation/deintercalation process, but not the total amount of bronzes. The oxidation of pre-adsorbed CO was shifted to lower potentials for WOx containing electrodes, suggesting that Pt-WOx is a more CO-tolerant catalyst than Pt. For the HOR, Pt on thicker films of WOx showed an increased limiting current, most likely originating from the increased electrochemically active surface area due to proton conductivity and hydrogen permeability in the WOx film. From measurements in liquid electrolyte it was seen that the system behaved very differently compared to the fuel cell measurements. This exemplifies the large differences between the liquid electrolyte and fuel cell systems. The thin-film model electrodes are shown to be a very useful tool to study the effects of introducing new materials in the PEFC catalysts. The fact that a variety of different measurements can be performed with the same electrode structure is a particular strength. 相似文献
12.
We propose a new strategy for improving the charge selectivity of carbon nanotubes (CNTs) for organic photovoltaic cells (OPVCs). The strategy involves the coating of an ultrathin layer of titanium suboxide (TiOx) on CNTs by atomic layer deposition (ALD). ALD can facilitate that conformal and uniform coating of TiOx on CNT networks while preserving their nanoporous structure. We used the TiOx-coated CNT networks as an electron transport layer in inverted OPVCs. TiOx-coated CNTs can provide electrons with an extremely fast conductive path through CNTs and selectively block the holes by means of the hole-barrier property of the TiOx in OPVCs. The nanoporous structure of TiOx-coated CNT networks can improve the device performance of OPVCs due to synergetic effects of the electron selective transport property of TiOx and the high conductivity of CNTs. In addition, further improvement of device performance can be achieved by adding a hole transport layer (MoO3) between the active layer and the Au electrode. 相似文献
13.
《Journal of the European Ceramic Society》2007,27(13-15):3601-3604
TiO2 is an insulator, but using specific dopants, can modify sharply its electronic structure towards semiconducting behavior. This type of response is widely applied in many electrochemical and electrocatalytical devices, namely chlorine production, hydrocarbon oxidation, CO and CO2 hydrogenation and as electroactive substrata for biological cell growth.Combustion synthesis is a very simple, rapid and clean method for material preparation, which will be used in the preparation of the (1 − x)TiO2–xSnO2, x = 0.05–0.3. Tin oxalate and titanium isopropoxide are used as precursors for the synthesis. The as-prepared powders are fine and homogeneous, the average particle size is in the range of 5–10 nm, powders and ceramic compact bodies are characterized by DRX, SEM–TEM–EDX, DTA–TG and EIS. The impedance spectroscopy of the sample 10 mol% of SnO2 indicates the presence of several phases which promote a matrix composite based in an electrical TiO2 insulator compatible with an electronic conducting phase tin rich. This could be attributed to the spinodal decomposition effect observed in TiO2–SnO2 system. 相似文献
14.
Microstructure development of hydrothermally grown TiO2 thin films with vertically aligned nanorods
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TiO2 (rutile) thin films were deposited via a hydrothermal process by adjusting the amount of ethanol, deposition time, and temperature. Especially, various amounts of ethanol generated different degrees of supersaturation in precursor solution. It allowed us to systematically change the width, lengths, and crystallinity of a vertically aligned 1‐D nanorod structure of TiO2 films. The oriented attachment, confirmed by scanning electron microscopy and transmission electron microscopy, was shown to be responsible for their lateral growth of TiO2 nanorods bundled by numerous well‐oriented nanowires and their vertical growth. TiO2 nanorod thin films were also characterized via X‐ray diffraction and UV‐Vis‐NIR spectrophotometer to find a correlation between the process conditions and nanostructural evolution. Dye sensitized solar cells were assembled to relate the nanostructures of TiO2 films with the effectiveness of its role as a photoelectrode. 相似文献
15.
《Ceramics International》2020,46(13):21388-21394
In this work, WO3 films were synthesized by glancing angle deposition (GLAD) and conventional planar deposition respectively. By depositing Pt on WO3 by GLAD, the NO2 sensitivity of WO3 films were significantly improved. The structural characteristics and NO2 sensing properties of the films were investigated in order to establish the enhancement mechanism. The results show WO3 films prepared by GLAD have porous nanorod-like structure, and isolated Pt clusters are distributed on WO3. The nanostructured Pt/WO3 films show high sensitivity to NO2 at 150 °C, detecting as low as 80 ppb NO2 with a response of 1.23. Meanwhile, the films also exhibit high NO2 selectivity against NH3, CO, acetone and ethanol. The excellent NO2 sensing properties of the Pt/WO3 films can be explained due to large specific surface area of nanorod-like WO3, catalysis of Pt and Schottky barriers at interfaces. The reliable Pt/WO3 nanostructure prepared by GLAD could be potentially applied in low-temperature, highly sensitive NO2 sensor for micro-electro-mechanical system (MEMS). 相似文献
16.
In this study, the photocatalysis of hybrid WO3/TiO2 films with different loadings of WO3 were investigated with and without potential bias. It was clearly indicated that hybrid WO3/TiO2 films show less photo-reactivity under only UV-irradiation, while more effective photocatalysis under potential bias than
either TiO2 or WO3 by themselves, their photocatalytic performance depending on the loadings of WO3. In particular, a hybrid WO3/TiO2 film involving an amorphous-like WO3 phase plays a significant role in an enhancement of the electrochemically assisted photocatalysis. 相似文献
17.
Atomic layer deposition (ALD) of controlled-thickness TiO2 films was carried out on particle substrates in a fluidized bed reactor for the first time. Films were deposited on 550 nm SiO2 spheres and 65 nm ZnO nanoparticles for enhanced optical properties. Nanoparticles were fluidized with the assistance of a magnetically-coupled stirring unit. The metalorganic precursor titanium tetraisopropoxide was used here followed by either H2O or H2O2 to deposit TiO2 at various substrate temperatures. Growth rates of 0.01 nm/cycle and 0.04 nm/cycle were achieved when using H2O and H2O2 as the oxidizer, respectively. These conformal TiO2 films were verified using HRTEM, ICP-AES, XPS and UV absorbance measurements. The specific surface area changed appropriately after the particle size increased by the deposition of films with a given density, which showed that primary particles were not agglomerated together due to the coating process. In situ mass spectrometry was used to monitor reaction progress throughout each ALD reaction cycle. Bulk quantities of powder were successfully functionalized by TiO2 nanofilms without wasting excess precursor. 相似文献
18.
Woo-Hee Kim Hyungjun Kim Han-Bo-Ram Lee 《Journal of Coatings Technology and Research》2017,14(1):177-183
Thin film optics, based on light interference characteristics, are attracting increasing interest because of their ability to enable a functional color coating for various applications in optical, electronic, and solar industries. Here, we report on the dependence of coloring characteristics on single-layer TiO2 thicknesses and alternating TiO2/Al2O3 multilayer structures prepared by atomic layer deposition (ALD) at a low growth temperature. The ALD TiO2 and Al2O3 thin films were studied at a low growth temperature of 80°C. Then, the coloring features in the single-layer TiO2 and alternating TiO2/Al2O3 multilayers using both the ALD processes were experimentally examined on a TiN/cut stainless steel sheet. The Essential Macleod software was used to estimate and compare the color coating results. The simulation results revealed that five different colors of the single TiO2 layers were shown experimentally, depending on the film thickness. For the purpose of highly uniform pink color coating, the film structures of TiO2/Al2O3 multilayers were designed in advance. It was experimentally demonstrated that the evaluated colors corresponded well with the simulated color spectrum results, exhibiting a uniform pink color with wide incident angles ranging from 0° to 75°. This article advances practical applications requiring highly uniform color coatings of surfaces in a variety of optical coating areas with complex topographical structures. 相似文献
19.
Y. Zheng K. L. Lv X. F. Li K. J. Deng J. Sun L. Q. Chen L. Z. Cui D. Y. Du 《化学工程与技术》2011,34(10):1630-1634
Anatase TiO2‐modified flower‐like Bi2WO6 nanostructures were prepared by a simple hydrothermal reaction followed by layer‐by‐layer deposition and calcination. The photocatalytic activity was evaluated using Brilliant Red X3B, an anionic azo dye, as the target organic pollutant under UV‐Vis light irradiation. The experiment results showed that the photocatalytic activity of the hybrid increases first and then decreases with increasing loading amount of TiO2. The hybrid coated with four layers of TiO2 (containing 20 wt‐% TiO2) showed the highest photocatalytic activity, which is 10.45 and 3.20 times higher than that of pure Bi2WO6 and TiO2, respectively. The improved photocatalytic performance of TiO2‐modified Bi2WO6 nanostructures could be ascribed to the improved light‐harvesting ability, efficient photo‐generated electron‐hole separation, and enhanced adsorption of the dye. This work may shed light on the design of complex architectures and the exploitation of their potential applications. 相似文献
20.
Regina Villanueva Andrés Gómez David Vie Eduardo Martínez Aurelio Beltrán Fernando Sapiña Jaume Vila 《Journal of the American Ceramic Society》2013,96(4):1324-1331
Nanocrystalline TiO2 and Ti1?xVxO2 (x = 0.01) powders have been prepared by thermal decomposition, in air, of amorphous precursors resulting from the freeze‐drying of appropriate solutions. In addition, TiO2?xNy (anatase and rutile) and TiOxNy (rock‐salt) have been prepared by thermal treatment in ammonia of a crystalline precursor (TiO2 obtained at 673 K). TEM and SEM images, as well as the analysis of the X‐ray diffraction (XRD) patterns, show the nanoparticulated character of those solids obtained at low temperatures, with typical particle sizes in the 10–20 nm range when prepared at 673 K. The UV–Vis results indicate both the insertion of V in the anatase lattice and the feasibility of nitridation at low temperatures. The photocatalytic properties of these materials (as prepared and after their incorporation to mortar samples) in the degradation of nitrogen oxides have been preliminary evaluated. Although N‐doping enhances the photocatalytic activity of the TiO2 matrix, V‐doping worsens it. 相似文献