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1.
Ferroelectric Pb(Zr0.52 Ti0.48)O3 thin films were prepared by sol-gel processing on the Pt/Ti/SiO2/Si(100) substrates. Effects of the concentration (0.2–0.8 M) of the starting solution (Pb/Zr/Ti= 1.1/0.52/0.48) and the sintering temperature (500–700 ‡C) on crystallinity, microstructure and electrical properties of PZT thin films were investigated. For the thin film prepared at 0.4 M starting solution, the highest crystallinity appeared at a sintering temperature of 650 ‡C. The average grain size of the PZT thin films was about 0.17 Μm. The film thickness was about 0.2 Μm. The relative dielectric constant and the dissipation factor of the film measured at 1 kHz were about 750 and 4.3%, respectively. The remnant polarization (Pr) and coercive field (Ec) of the film measured at the applied voltage of 5 V were about 49 ΜC/cm2 and 134 kV/cm, respectively.  相似文献   

2.
Strontium titanate (Sr x Ti y O z ) thin films were prepared by a chemical vapor deposition method using gaseous compounds, obtained by vaporizing a solid mixture of Sr(dpm)2 and Ti(O-iPr)2(dpm)2 in one step, as the metal sources. The compositions of the films changed in proportion to the ratio of the precursors in the solid mixture, which is contrary to the case of films obtained from a mixture of individual precursor vapors. In the latter case, the film composition was not proportional to the mixing ratio of the precursors. The strontium titanate concentration in the film was changed by the deposition temperature even when the Sr/Ti ratio of the feed was fixed, i.e., the Sr/Ti ratio in the film decreased at high temperatures. An SrTiO3 film, with an Sr/Ti ratio of 1/1, was obtained at 450 ‡C by using vapors from a solid mixture containing the metal precursors at a Sr/Ti of 1/1. The temperature, 450 ‡C in this case, was lower than that for producing the same film composition by a liquid injection method, 550 ‡C. The decomposition of the Ti and Sr precursors included in the solid mixture and possible reactions between them at elevated temperatures were investigated by thermogravimetry, differential scanning calorimetry, and mass spectrometry. When the solid mixture was heated, the Sr-O bond, that connected Sr to the dpm ligand, was dissociated at temperatures lower than 100 ‡C and the isopropoxide ligand of the Ti precursor was dissociated from the Ti atom at temperatures below 150 ‡C. At 162 ‡C, Ti(O-iPr)2(dpm)2 melted, forming an oligomer by reaction with surrounding Ti and Sr precursors. This reaction was confirmed by the presence of a mass peak at m/e=585, corresponding to a hetero-metallic compound containing Sr and Ti. The hetero-metallic compound vaporized at temperatures below 200 ‡C and eventually participated in the formation of a SrTiO3 film.  相似文献   

3.
Titanium oxide thin films were deposited on p-type Si(100), SiO2/Si, and Pt/Si substrates by plasma enhanced chemical vapor deposition using high purity Ti(O-i-C3H7)4 and oxygen. As-deposited amorphous TiO2 thin films were treated by rapid thermal annealing (RTA) in oxygen ambient, and the effects of RTA conditions on the structural and electrical properties of TiO2 films were studied in terms of crystallinity, microstructure, current leakage, and dielectric constant. The dominant crystalline structures after 600 and 800 ‡C annealing were an anatase phase for the TiO2 film on SiO2/Si and a rutile phase for the film on a Pt/Si substrate. The dielectric constant of the as-grown and annealed TiO2 thin films increased depending on the substrate in the order of Si, SiO2/Si, and Pt/ Si. The SiO2 thin layer was effective in preventing the formation of titanium silicide at the interface and current leakage of the film. TEM photographs showed an additional growth of SiOx from oxygen supplied from both SiO2 and TiO2 films when the films were annealed at 1000 ‡C in an oxygen ambient. Intensity analysis of Raman peaks also indicated that optimizing the oxygen concentration and the annealing time is critical for growing a TiO2 film having high dielectric and low current leakage characteristics.  相似文献   

4.
Spinel-LiMn2O4 thin films were fabricated on stainless steel substrate by the r.f.-sputtering method. They were annealed within the range 400–700 °C for 1 h in O2 and their electrochemical performance was compared to that of as-deposited film. The thin films were characterized by X-ray diffractometry and electron spectroscopy for chemical analysis (ESCA). Charge–discharge tests were carried out in an LiClO4/propylene carbonate solution. The films heat-treated at 400–700 °C exhibited excellent cyclability over a wide potential region from 2.0 to 4.3 V vs Li/Li+.  相似文献   

5.
M-type strontium hexaferrite was prepared by mechanosynthesis using high-energy ball milling. The influence of milling parameters, hematite excess and annealing temperature on magnetic properties of SrFe12O19 were investigated. Commercial iron and strontium oxides were used as starting materials. It was found that mechanical milling followed by an annealing treatment at low temperature (700 °C) promotes the complete structural transformation to Sr-hexaferrite phase. For samples annealed at temperatures from 700 to 1000 °C, saturation magnetization values (Ms) are more sensitive to annealing temperature than coercivity values (Hc). The maximum Ms of 60 emu/g and Hc of 5.2 kOe were obtained in mixtures of powders milled for 5 h and subsequently annealed at 700 °C. An increase in the annealing temperature produces negligible changes in magnetic saturation and coercivity. An excess of hematite as a second phase produces a slight decrease in the saturation magnetization but leads to a significant increase in coercive field, reaching 6.6 kOe.  相似文献   

6.
In this paper, indium (In) films were deposited on glass substrates using DC sputtering method. Multiwalled carbon nanotubes (MWCNTs) and dispersant were dissolved in alcohol, and the mixed solution was deposited on the In films using the spray method. The bi-layer MWCNTs-In2O3 films were annealed at different temperatures (from room temperature to 500°C) in O2 atmosphere. The influences of annealing temperature on the characteristics of the bi-layer MWCNTs-In2O3 films were investigated by scanning electron microscopy, X-ray diffraction pattern, Fourier transform infrared (FT-IR) spectroscopy, and Raman spectroscopy. A separative extended-gate field-effect transistor (EGFET) device combined with a bi-layer MWCNTs-In2O3 film was constructed as a pH sensor. The influences of different annealing temperatures on the performances of the EGFET-based pH sensors were investigated. We would show that the pH sensitivity was dependent on the thermal oxygenation temperature of the bi-layer MWCNTs-In2O3 films.  相似文献   

7.
Lithium zirconium phosphate (LiZr2P3O12) thin films have been prepared on platinized silicon substrates via a chemical solution deposition approach with processing temperatures between 700°C and 775°C. Films that were subject to a single high-temperature anneal were found to crystallize at temperatures above 725°C. Crystallization was observed in films annealed after each deposited layer at 700°C and above. In both cases, grain size was found to increase with annealing temperature. Ion conductivity was found to increase with annealing temperature in singly annealed films. In per-layer annealed films ion conductivity was found to initially increase then decrease with increasing annealing temperature. A maximum ion conductivity of 1.6 × 10−6 S/cm was observed for the singly annealed 775°C condition, while a maximum ion conductivity of 5.8 × 10−7 S/cm was observed for the 725°C per-layer annealed condition. These results are consistent with an increasing influence of cross-plane, internal interface resistance and vapor phase carrier loss in the per-layer annealed samples. This work demonstrates that post-deposition processing methods can strongly affect the ion conducting properties of LiZr2P3O12 thin films.  相似文献   

8.
A clear ethanol based precursor sol obtained using diethanolamine has been utilized for the deposition of TiO2 films annealed at different temperatures. The influence of annealing temperature on the structural, optical and electrochemical properties of TiO2 thin films has been examined. Diethanolamine stabilizes the precursor sol due to its chelate forming ability with the alkoxides. It reacts as a tridentate ligand with the titanium isopropoxide. The threshold for the onset of crystallization in the films is identified at a temperature of 300 °C. The SEM study on the films elucidates segregation of irregularly shaped features into finer round clusters as a function of annealing temperature. As determined from the AFM study, the roughness parameter in the films has shown an increase with the annealing temperature. Photoluminescence measurements have given an indirect evidence for the presence of stoichiometric titanium oxide in the films. An optimum crystallite size and high ion storage capacity in the 300 °C annealed film has led to its superior electrochromic activity with the transmission modulation and coloration efficiency of the same film being 42% and 8.1 cm2 C−1, respectively at 550 nm. The highest degree of porosity in the 300 °C annealed film as established from the SEM study is also the reason behind its best electrochromic performance. In addition, the 300 °C annealed film also exhibits the fastest coloration switching kinetics.  相似文献   

9.
Bismuth titanate thin films are deposited on ITO/glass substrates by rf magnetron sputtering at room temperature using a Bi4Ti3O12 ceramic target. The deposited Bi4Ti3O12 films are annealed in a conventional furnace in ambient air for 10 min at temperatures ranging from 550 to 640 °C. One specimen is annealed in a crucible containing additional Bi2O3 compensation powder, while the other specimen is annealed in ambient air. XRD analysis shows that the crystal phases of films annealed with Bi2O3 powder are better than those of films annealed without Bi2O3 powder. Furthermore, the EDS results reveal that the bismuth weight percentage of the former is higher than that of the latter. SIMS analysis shows that the bismuth decreases near the surface of Bi4Ti3O12 film annealed without Bi2O3 powder, but reveals a stable distribution throughout the film annealed with Bi2O3 powder. These results imply that bismuth is readily evaporated during the thermal treatment process, particularly from the region near the film surface. Finally, the dielectric and polarization properties of the thin films annealed with Bi2O3 powder are found to be superior to those of the films annealed in ambient air.  相似文献   

10.
Mesoporous TiO2 films were synthesized using a sol–gel process with a tri-block copolymer (Pluronic F127) as a structure directing agent. The films were dip-coated onto conductive glass substrates followed by thermal treatment to remove the polymeric surfactant. The specific surface area, the pore size and morphology, and the crystallinity of the films were characterized. The analysis showed the structural properties of the films could be tailored by varying the surfactant concentration as well as the annealing temperature. The photocurrent responses of the prepared films were measured using a three-electrode photoelectrochemical cell in the presence of oxalic acid. When annealed at 450 °C, the dense electrode (control sample) had the strongest photoelectrocatalytic oxidation aptitude toward oxalic acid. The lower photocurrent response of the mesoporous electrodes compared to the dense electrode can be explained by poor inter-particle connectivity within the mesoporous TiO2 network, leading to high electron transport resistance. The mesoporous electrode annealed at 550 °C, with improved connectivity, outperformed the dense electrode at a high oxalic concentration, as the lower surface area of the dense electrode restricted photoelectrocatalysis reactions on the surface. A further increase in annealing temperature to 650 °C resulted in a poor photocurrent response as the significant decrease in surface area outweighed the beneficial effect of improved connectivity.  相似文献   

11.
Thin-films of La2Ti2O7 were obtained by dip-coating process using a precursor salt in nitric acid solution. The effects of solution concentration, withdrawal speed, post-annealing duration and temperature were investigated both on grain size and orientation of the La2Ti2O7 thin layers. In addition, a target with the required stoichiometry for PVD deposition of La-substituted Bi4Ti3O12 (BLT) was successfully sintered by spark plasma sintering (SPS) at 750 °C. Finally (0 1 1)-oriented BLT ferroelectric films have been grown by RF sputtering on (1 1 0)-oriented La2Ti2O7 polycrystalline thin-film. A preferential orientation of BLT thin films has been obtained after annealing at a temperature lower than 650 °C.  相似文献   

12.
The effects of annealing temperature on the photocatalytic activity of nitrogen-doped (N-doped) titanium oxide (TiO2) thin films deposited on soda-lime-silica slide glass by radio frequency (RF) magnetron sputtering have been studied. Glancing incident X-ray diffraction (GIAXRD), Raman spectrum, scanning electron microscopy (SEM), atomic force microscopy (AFM) and UV-vis spectra were utilized to characterize the N-doped TiO2 thin films with and without annealing treatment. GIAXRD and Raman results show as-deposited N-doped TiO2 thin films to be nearly amorphous and that the rutile and anatase phases coexisted when the N-doped TiO2 thin films were annealed at 623 and 823 K for 1 h, respectively. SEM microstructure shows uniformly close packed and nearly round particles with a size of about 10 nm which are on the slide glass surface for TiO2 thin films annealed at 623 K for 1 h. AFM image shows the lowest surface roughness for the N-doped TiO2 thin films annealed at 623 K for 1 h. The N-doped TiO2 thin films annealed at 623 K for 1 h exhibit the best photocatalytic activity, with a rate constant (ka) of about 0.0034 h−1.  相似文献   

13.
(Ta2O5)1-x- (TiO2)x (TTOx) thin films, with x = 0, 0.03, 0.06, 0.08, and 0.11, were deposited using magnetron direct current (DC) sputtering method onto the P/boron-silicon (1 0 0) substrates by varying areas of Tantalum and Titanium metallic targets, in oxygen environment at ambient temperature. The as-deposited thin films were annealed at temperatures ranging from 500 to 800 °C. Generally, the formation of the Ta2O5 structure was observed from the X-ray diffraction measurements of the annealed films. The capacitance of prepared metal– oxide– semiconductor (MOS) structures of Ag/TTOx/p-Si was measured at 1 MHz. The dielectric constant of the deposited films was observed altering with varying composition and annealing temperature, showing the highest value 71, at 1 MHz, for the TTOx films, x = 0.06, annealed at 700 °C. With increasing annealing temperature, from 700 to 800 °C, the leakage current density was observed, generally decreasing, from 10?5 to 10?8 A cm?2, for the prepared compositions. Among the prepared compositions, films with x = 0.06, annealed at 800 °C, having the observed value of dielectric constant 48, at 1 MHz; and the leakage current density 2.7 × 10?8 A cm?2, at the electric field of 3.5 × 105 V cm?1, show preferred potential as a dielectric for high-density silicon memory devices.  相似文献   

14.
In this work, the influence of annealing temperature on the ferroelectric electron emission behaviors of 1.3-μm-thick sol–gel PbZr0.52Ti0.48O3 (PZT) thin film emitters was investigated. The results revealed that the PZT films were crack-free in perovskite structure with columnar-like grains. Increasing annealing temperature led to the growth of the grains with improved ferroelectric and dielectric properties. The remnant polarization increased slightly from 35.3 to 39.6 μC/cm2 and the coercive field decreased from the 56.4 to 54.6 kV/cm with increasing annealing temperature from 600 to 700 °C. The PZT film emitters exhibited remarkable ferroelectric electron emission behaviors at the threshold voltage above 95 V. The film annealed at 700 °C showed a relatively lower threshold voltage and higher emission current, which is related to the improved ferroelectric and dielectric properties at higher annealing temperature. The highest emission current achieved in this work was around 25 mA at the trigger voltage of 160 V.  相似文献   

15.
TiO2 thin films were prepared by RF magnetron sputtering onto glass substrates and tungsten was deposited onto these thin films (deposition time 15-60 s) to form W-TiO2 bi-layer thin films. The crystal structure, morphology, and transmittance of these TiO2 and W-TiO2 bi-layer thin films were investigated. Amorphous, rutile, and anatase TiO2 phases were observed in the TiO2 and W-TiO2 bi-layer thin films. Tungsten thickness and annealing temperature had large effects on the transmittance of the W-TiO2 thin films. The W-TiO2 bi-layer thin films with a tungsten deposition time of 60 s were annealed at 200 °C-400 °C. The band gap energies of the TiO2 and the non-annealed and annealed W-TiO2 bi-layer thin films were evaluated using (αhν)1/2 versus energy plots, showing that tungsten thickness and annealing temperature had major effects on the transmittance and band gap energy of W-TiO2 bi-layer thin films.  相似文献   

16.
Thermal atomic layer-deposited (ALD) aluminum oxide (Al2O3) acquires high negative fixed charge density (Qf) and sufficiently low interface trap density after annealing, which enables excellent surface passivation for crystalline silicon. Qf can be controlled by varying the annealing temperatures. In this study, the effect of the annealing temperature of thermal ALD Al2O3 films on p-type Czochralski silicon wafers was investigated. Corona charging measurements revealed that the Qf obtained at 300°C did not significantly affect passivation. The interface-trapping density markedly increased at high annealing temperature (>600°C) and degraded the surface passivation even at a high Qf. Negatively charged or neutral vacancies were found in the samples annealed at 300°C, 500°C, and 750°C using positron annihilation techniques. The Al defect density in the bulk film and the vacancy density near the SiOx/Si interface region decreased with increased temperature. Measurement results of Qf proved that the Al vacancy of the bulk film may not be related to Qf. The defect density in the SiOx region affected the chemical passivation, but other factors may dominantly influence chemical passivation at 750°C.  相似文献   

17.
Using hydrofluoric acid as acid catalyst, F doped nanoporous low-k SiO2 thin films were prepared through sol-gel method. Compared with the hydrochloric acid catalyzed film, the films showed better micro structural and electrical properties. The capacitance-voltage and current-voltage characteristics of F doped SiO2 thin films were then studied based on the structures of metal-SiO2-semiconductor and metal-SiO2-metal, respectively. The density of state (DOS) of samples deposited on metal is found to decrease to a level of 2 × 1017 eV−1 cm−3. The values of mobile ions, fix positive charges, trapped charges and the interface state density between the SiO2/Si interfaces also decrease obviously, together with the reduction of the leakage current density and the dielectric constant, which imply the improvement of the electrical properties of thin films. After annealing at a temperature of 450C, the lower values of the leakage current density and dielectric constant could be obtained, i.e. 1.06 × 10−9 A/cm2 and 1.5, respectively.  相似文献   

18.
《Ceramics International》2017,43(8):5901-5906
0.65Pb(Mg1/3Nb2/3)O3-0.35PbTiO3 (0.65PMN-0.35PT) thin films were deposited on Pt/Ti/SiO2/Si substrates annealed from 550 to 700 °C using sol-gel process. The effects of annealing temperature on microstructure, insulating, ferroelectric and dielectric properties were characterized. The result reveals that 0.65PMN-0.35PT thin films possess a polycrystalline structure, matching well with the perovskite phase despite the existence of a slight pyrochlore phase. The film samples annealed at all temperatures exhibit relatively dense surfaces without any large voids and the grain size increases generally with the increase of the annealing temperature. Meanwhile, pyrochlore phase is considerably generated because of the deformation of perovskite phase caused by volatilization of Pb at an excessive high-temperature. The film annealed at 650 °C exhibits superior ferroelectricity with a remanent polarization (Pr) value of 13.31 μC/cm2, dielectric constant (εr) of 1692 and relatively low dielectric loss (tanδ) of 0.122 at 104 Hz due to the relatively homogeneous large grain size of 130 nm and low leakage current of approximately 10-6 A/cm2.  相似文献   

19.
A systematic study of the etch characteristics of SrBi2Ta2O9 (SBT) thin films in inductively coupled plasmas (ICPs) has been performed with various chemistries of Cl2/Ar, Cl2/O2/Ar, Cl2/NF3/Ar, and Cl2/NF3/O2/Ar. Etch rate was dependent on plasma chemistries and parameters. Addition of O2 stabilized the perovskite structure of SBT film and suppressed the etch rate, but NF3 enhanced the etch rate substantially mainly due to reactive fluorine radicals. Maximum etch rates obtained were: 740 å/min with Cl2/Ar, 320 å/min with Cl2/O2/Ar, 1,500 å/min with Cl2/NF3/Ar, and 1,600 å/min with Cl2/NF3/O2/Ar at 5 mTorr, 700 W. ICP power and 150 W. rf chuck power. Electrical properties of the SBT films were quite dependent on plasma chemistries employed; Cl2/NF3/O2/Ar showed the least damage in the films and resulted in the best P-E hysteresis loop having remnant polarization (2Pr)=12.3 ΜC/cms2 and coercive field (Ec)=41.9 V/cm.  相似文献   

20.
Development in highly active catalysts for the reforming of methane with CO2 and partial oxidation of methane was conducted to produce hydrogen and carbon monoxide with high reaction rates. An Ni-based four-components catalyst, Ni-Ce2O3-Pt-Rh, supported on an alumina wash-coated ceramic fiber in a plate shape was suitable for the objective reaction. By combining the catalytic combustion of ethane or propane, methane conversion was markedly enhanced, and a high space-time yield of syngas, 25,000 mol/l·h was obtained at a catalyst temperature of 700 ‡C or furnace temperature of 500 ‡C. The extraordinary high space-time yield of syngas was also confirmed even under the very rapid flow rate conditions as a contact time of 3 m-sec by using a monolithic shape of catalyst bed without back pressure.  相似文献   

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