Memristors, as next-generation memory devices, have garnered significant academic interest. Among them, TiO2/TiO2-x based memristors have particularly attracted substantial scholarly attention. Research on the activation and stability of TiO2 based memristor devices through process parameters is essential. Here, to determine the impact of process parameters on the activation of TiO2/TiO2-x based memristor devices, we fabricated the memristor devices using a sputtering system andconducted annealing at 400℃. Additionally, to analyze the electrical characteristics of the devices, we measured the I-V curves and C-V curves. Also, we examined TiO2/TiO2-x based memristor devices surface using SEM. Consequently, it was observed that the devices subjected to annealing exhibited improved hysteresis curves in the I-V characteristics, a reduced bandgap, and changes in resistance compared to the non-annealed devices. The retention test results further demonstrated that the set/reset characteristics of the devices were stable, confirming their potential applicability as memory devices.
The silicon dioxide (SiO2) was deposited using various gas as oxygen and nitrous oxide (N2O) in nowadays. In order to improve electrical characteristics and the interface state density (D_{it}) in low temperature, It was deposited with carbon dioxide (CO2) and silane (SiH4) gas by inductively coupled plasma chemical vapor deposition (ICP-CVD). Each D_{it} of SiO2 using CO2 and N2O gas was 1.30×1010 cm-2·eV-1 and 3.31×1010 cm-2·eV-1. It showed SiO2 using CO2 gas was about 2.55 times better than N2O gas. After 10 years when the thin film was applied to metal/insulator/semiconductor(MIS)-nonvolatile memory(NVM), MIS NVM using SiO2(CO2) on tunneling layer had window memory of 2.16 V with 60% retention at bias voltage from +16 V to -19 V. However, MIS NVM applied SiO2(N2O) to tunneling layer had 2.48 V with 61% retention at bias voltage from +20 V to -24 V. The results show SiO2 using CO2 decrease the D_{it} and it improves the operating voltage.
Titanium oxide (TiO2) thin films were synthesized on polymer insulator and Si substrates by atomic layer deposition (ALD) method. The surface and electrical properties of TiO2 films synthesized at various ALD cycle numbers were investigated. The synthesized TiO2 films exhibited higher contact angle and smooth surface. The contact angle of TiO2 films was increased with the increase of ALD-cycle number. Also, the rms surface roughness of films was slightly rough with the increase of ALD-cycle number. The leakage current on TiO2 film surface synthesized at various conditions were uniformed, and the values were decreased with the increase of ALD-cycle number. In the results, the performance of TiO2 films for self-cleaning critically depended on a number of ALD-cycle.
Titanium oxide (TiO2) thin films were fabricated by unbalanced magnetron (UBM) sputtering. The fabricated TiO2 films were treated by oxygen plasma under various RF powers. We investigated the characteristics of oxygen plasma treatment on the surface, structural, and physical properties of TiO2 films prepared at various plasma treatment RF powers. UBM sputtered TiO2 films exhibited higher contact angle value, smooth surface, and amorphous structure. However, the rms surface roughness TiO2 films were rough, and the contact angle value was decreased with the increase of the plasma treatment RF power Also, the hardness value of TiO2 film as physical properties was slightly increased with the increase of the plasma treatment RF power. In the results, the performance of TiO2 films for self cleaning critically depended on the with the plasma treatment RF power.
In this work, LiMn2O4 and LiNi1/3Mn1/3Co1/3O2 cathode materials are mixed by some specific ratios to enhance the practical capacity, energy density and cycle performance of battery. At present, the most used cathode material in lithium ion batteries for EVs is spinel structure-type LiMn2O4. LiMn2O4 has advantages of high average voltage, excellent safety, environmental friendliness, and low cost. However, due to the low rechargeable capacity (120 mAh/g), it can not meet the requirement of high energy density for the EVs, resulting in limiting its development. The battery of LiMn2O4-LiNi1/3Mn1/3Co1/3O2 (50:50 wt%) mixed cathode delivers a energy density of 483.5 mWh/g at a current rate of 1.0 C. The accumulated capacity from 1st to 150th cycles was 18.1 Ah/g when the battery is cycled at a current rate of 1.0 C in voltage range of 3.2~4.3 V.
A novel heteroleptic ruthenium(II) complex bearing a 4-picolinic acid unit as anchoring ligands (trans-dithiocyanato bis(4-picolinic acid)ruthenium(II) (trans-H1)) was synthesized and its chemical structure was identified by 1H-NMR, FT-IR and mass spectroscopy. The optical, thermal, electrochemical and dye adsorption properties of trans-H1 dye were investigated and compared with those of the gold standard ruthenium complex, Ru(4,4``-dicarboxy-2,2``-bipyridine)2cis(NCS)2 (N3). DSSCs based on trans-H1 dyes were examined under the illumination of AM 1.5 G, 100 mWcm-2 and exhibited typical photovoltaic properties with an open-circuit voltage (VOC) of 0.46 V, a short-circuit current (JSC) of 4.10 mA·cm-2, a fill factor (FF) of 60.4%, and a conversion efficiency (PCE) of 1.14%.
(YNdSm)-Ba-Cu-O system high Tc composite superconductors were directionally grown by zone melting process, having large temperature gradient, in air atmosphere. Cylindrical green rods of (YNdSm)1.8Ba2.4Cu3.4Ox [(YNS)1.8]composite oxides by CIP (cold isostatic pressing) method using rubber mold were fabricated. Themicrostructure and superconducting properties were investigated by XRD, TEM and SQUID magnetometer. The size of nonsuperconducting (YNdSm)2BaCuO5 inclusions of the melt-textured (YNS)1.8 sample with CeO2 additive were remarkably reduced and uniformly distributed within the superconducting (YNS)1.8 matrix. (YNS)1.8 samples, with / without CeO2 additive, showed an onset Tc ≥ 90 K and sharp superconducting transition. The critical current density Jc value of the (YNdSm)1.8 superconductor with CeO2 additive were 840 A, 1.2×104 A/cm2 in 77 K, 0Tesla by direct current transport method.
In this paper, in order to develop excellent Pb-free composition ceramics for ultrasonic sensor. The SnO2-doped (Na0.525K0.443Li0.037)(Nb0.883Sb0.08Ta0.037)O3)(abbreviated as NKL-NST) ceramics have been synthesized using the ordinary solid state reaction method. The effect of SnO2-doping on their dielectric and piezoelectric properties was investigated. The ceramics doped with 0 wt% SnO2 have the optimum values of piezoelectric constant(d33), piezoelectric figure of merit(d33·g33), planar piezoelectric coupling coefficient(kp) and density : d33= 195[pC/N], d33·g33=5.62 pm2/N.kp= 0.40, density= 4.436[g/cm3]. suitable for duplex ultrasonic sensor application.
The photoinduced hydrophilicity of TiO2/WO3 double layer films was fabricated by using a conventional rf-magnetron sputtering method. The photoinduced hydrophilic reaction of the TiO2 surface was enhanced by the presence of WO3 under the TiO2 layer by irradiation of a 10 W cylindrical fluorescent light bulb. However, when the TiO2 and WO3 layers were separated by an insulating layer, the surface did not appeared high hydrophilic,under the same light bulb. The enhanced photoinduced hydrophilic reaction can be explained by the charge transfer between TiO2 and WO3 layers. It was also demonstrated that visible light passing through the TiO2 layer could excite WO3. Thus, visible light can be used for the hydrophilic reaction in the present TiO2/WO3 system.
Rhodamine B (RhB) was utilized as a dye sensitizer for dye-sensitized solar cells (DSSCs) and its photovoltaic property was examined under the illumination of AM 1.5 G, 100 mWcm-2. DSSCs based on RhBexhibited typical photovoltaic properties with an open-circuit voltage (VOC) of 0.34 V, a short-circuit current (JSC) of 1.55 mA·cm-2, a fill factor (FF) of 50%, and a conversion efficiency (PCE) of 0.26%. In order to further improve the photovoltaic properties of RhB-based DSSCs, the effect of (i) incorporating a strong electron-donating NCS unit into the RhB molecular backbone, (ii) combining a bis-negatively charged zinc complex anion (Zn-dmit2, dmit=di-mercapto-dithiol-thione) with the amine cation of RhB, (iii) co-adsorbing RhB dyes with chenodeoxycholic acid (CDCA) molecules onto porous TiO2 electrodes, was investigated and discussed.
Nano-size BaTiO3 powder was synthesized by relatively simple hydrothermal reaction method. Finely dispersed Ti hydroxide precursor was first precipitated using Ti(SO4)2 and NaOH solution by applying ultrasonic power and washed thoroughly to remove SO4 2- and Na+ ion. Then hydrothermal reaction was done at 160℃ for 6 hrs using solution prepared by washed Ti hydroxide precursor slurry and Ba(OH)2ㆍ8H2O with Ti:Ba mole ratio of 1:1. 200 ~ 500 nm size and uniform size distributed BaTiO3 powder was synthesized by relatively low temperature and simple process.
In this paper, TiO2 based thin-film transistors (TFTs) were fabricated using by an atomic layer deposition with high aspect ratio and excellent step coverage. Ti02 semiconducting layer was deposited showing a rutile phase through the rapid thermal annealing process, and exhibited TFT characteristics with a 200 pm channel length of low-leakage currents (none of current flow during off-state), stable threshold voltages (-10 V - 0 V), and a much higher on/off current ratio (
Some insulating materials are organized and analyzed with variables to obtain the optimized profile of encapsulated three phase of epoxy barrier which is applied to gas compartment and supporting conductors for high voltage GIS (gas insulated switchgear). The high voltage GIS is used in electrical power system and operating reliability. In this paper, optimization possibility of barrier shape including both electrical insulation performance and mechanical strength, premised on that condition minimizing volume and light weight should be kept for high voltage GIS, could be achieved by analysis simulation. As a result, filling material which is lower permittivity such as SiO2 instead of Al2O3 properly to the epoxy material, can be improved to increase the electrical insulation performance and mechanical strength for an optimized profile barrier of a high voltage GIS.
Composite ceramics of alumina-TZP(3Y) have good mechanical and electrical properties. So, They have been used as high strength refractory materials and thick film substrates, etc. In this study, Composite ceramics of alumina-TZP(3Y) were fabricated by uniaxial pressing and sintering at 1,400, 1,500, and 1,600℃, and their microstructures and mechanical properties were investigated. As the TZP(3Y) content in composite ceramics increases from 20 wt.% to 80 wt.%, the fracture toughness increases monotonically, which seems to be related to the higher relative density and/or toughening mechanism by means of stabilized tetragonal zirconia phase at room temperature. In contrast to the fracture toughness, Vickers hardness of the composite ceramics shows maximum value (1,938 Hv) at a 40 wt.% of TZP(3Y). The result of Vickers hardness is likely to be due to more dense sintered microstructure of composite ceramics than pure alumina and reinforcement of composite ceramics with TZP(3Y), considering that Vickers hardness of pure Al2O3 is greater than that of TZP(3Y). It is also shown that the ZrO2 particles are 1°Cated between Al2O3 grains and suppress grain growth each other.
Photo electrode is an important component of DSSC, so this paper did some research on it. Through the method of adding PEG additive into TiO2 paste, the electrical characteristics and efficienciesof DSSCs with photo electrode surface area were studied. In the case of not adding PEG in TiO2 paste,26 ㎛ thickness TiO2 photo electrode shows 5.081% efficiency. The highest short circuit current densitywas 10.476 mA/cm2. The structure of porous TiO2 film can be controlled through changing the PEGadditive amount in TiO2 paste and the molecular weight of PEG. When the additive amount of PEG20,000 in TiO2 paste reaches 5%, the peak efficiency with 26 ㎛ thickness TiO2 photo electrode was5.387% and its highest current density were 11.084 mA/cm2.
We have investigated the effect of electrical properties of amorphous InGaZnO thin filmtransistors (a-IGZO TFTs) by post thermal annealing in O2 ambient.The post-annealed in O2 ambienta-IGZOTFT is found to be more stable to be used for oxide-based TFT devices, and has betterperformance, such as the on/off current ratios, sub-threshold voltage gate swing, and, as well asreasonable threshold voltage, than others do. The interface trap density is controlled to achieve theoptimum value of TFT transfer and output characteristics. The device performance is significantlyaffected by adjusting the annealing condition. This effect is closely related with the modulation annealingmethod by reducing the localized trapping carriers and defect centers at the interface or in the channellayer.
MnO2-doped 0.985[Li0.04(Na0.545K0.46)0.96(Nb0.81Ta0.15Sb0.04)]O3+0.015KNbO3(0.985LNKNTS+0.015KNbO3)lead-free ceramics were fabricated by conventional solid state method to develop excellent dielectric andpiezoelectric properties. The result of X-ray diffraction patterns obviously indicated that all of thespecimen has pure perovskite structure without secondary phase. In addition, orthorhombic phase andcoexistance region of orthorhombic-tetragonal phase (MPB) were observed with amount of MnO2. Theoptimal values of ρ=4.70 g/cm3, d33=238 pC/N, kP=0.46, Qm=121, εr=849, and TC=225℃ were obtained at0.01 mol% MnO2 doped 0.985LNKNTS+0.015KNbO3 ceramics sintered at 990℃ for 5 h, respectively. Hence, it was indicated that the suitable amount of MnO2 could improve the electrical properties of0.985[Li0.04(Na0.545K0.46)0.96](Nb0.81Ta0.15Sb0.04)]O3+0.015KNbO3 ceramics.
The bipolar resistive switching characteristics of resistive random access memory (ReRAM) based on HfO2 thin films have been demonstrated by using Ag/HfO2/Pt structured ReRAM device. MIcrowave irradiation (MWI) treatment at low temperature was employed in device fabrication with HfO2thin films as a transition layer. Compared to the as-deposited Ag/HfO2/Pt device, highly improved uniformity characteristics of resistance values and operating voltages were obtained from the MWI treatment Ag/HfO2/Pt ReRAM device. In addition, a stable DC endurance (> 100 cycles) and a high data retention (> 104 sec) were achieved.
Photo electrode is an important component for DSSC. DSSCs electrical characteristics and efficiencies fabricated with different TiO2 photo electrodes thickness and modified phoro electrode surface area were studied. 11 ㎛ TiO2 photo electrode shows a 4.956% efficiency. The highest short circuit current density was a 9.949 mA/cm2. Efficiencies and short circuit current density increased as tape casting thickness decreased. Modified surface area of the photo electrode by needle stamp processing were studied. 200 times needle stamp processing on photo electrodes shows a highest 5.168% efficiency. Also the short circuit current density was a 10.261 mA/cm2.
In this work, according to temperature and time of hydrothermal synthesis, the electrochemical properties of TiIO2 particle using TTIP based on thanging temperature and time in the hydrothermal synthesis were analyzed and optimized temperature and time were derived. When hydrothermal synthesis were analyzed and optimized temperature and time were derived. When hydrothermal synthesis temperature and time were 200℃ and 1 h, respectively. The fabricated DSSC delivered the best electrochemical properties. In that case, TiO2 particle size was 13.018 nm, electron transport time was 2.34×103s and recombination time was 4.01×102s. The lowest impedance of 13.52 Ω and Voc, Jsc, FF is 0.70 V, 11.50 mAcm2, 65.62%, respectively and corresponding efficiency of 5.34% was considered as the optimal.
In this paper, we carried out the investigations of both etch characteristics and mechanisms for the SnO2 thin films in O2/BCl3/Ar plasma. The dry etching characteristics of the SnO2 thin films was studied by varying the O2/BCl3/Ar gas mixing ratio. We determined the optimized process conditions that were as follows: a RF power of 700 W, a DC-bias voltage of -150 V, and a process pressure of 2 Pa. The maximum etch rate was 509.9 nm/min in O2/BCl3/Ar=(3:4:16 sccm) plasma. From XPS analysis, the etch mechanism of the SnO2 thin films in the O2/BCl3/Ar plasma can be identified as the ion-assisted chemical reaction while the role of ion bombardment includes the destruction of the metal-oxide bonds as well as the cleaning of the etched surface form the reaction products.
In this study, the surface modification of copper foil using an inductively coupled O2 / Ar plasma as O2 gas fraction (0∼100%) was investigated in order to improve the surface characteristics. After plasma treatment, the measurement of the surface roughness, surface contact angle and surface energy were performed for the surface analysis of copper foil. As a result, the surface roughness and the surface energy were increased. And plasma diagnostics was performed by a double Langmuir probe (DLP) and optical emission spectroscopy (OES). Using these results, the plasma surface modification mechanism was investigated.
Indium Zinc Tin Oxide (IZTO) thin films were developed as an alternative to Indium Tin Oxide (ITO) thin films. ITO material which has been acknowledged with its low resistivity and optical transparency of 85-90% has been used as major transparent conducting oxide (TCO) materials. However, due to the limited source, high price, and instability problems at high temperature of indium, many researches has been focused on indium-saving TCO materials. Mason Group of Northwestern University was reported to expand the solubility limit up to 40% by co-doping with 1:1 ratio of Zn+2 and Sn+4 ions. In this study, the properties of IZTO thin films corresponding to Zn/Sn different ratio were investigated. In addition, the effect of substrate temperature variable to the structural, optical and electrical properties of IZTO thin films was investigated.
In this paper, the + 0.005KNhO: ÷ xwt9`o le02 lead-free piezoelectric ceramics for energy harvesting devices were fabricated by the conventiona] mixed oxide method. The microstructure, dielectric, and piezoelectric properties were investigated as a function of the Te09 addition. All the specimens showed an orthorhombic phase structure. At the composition ceramics doped with 0.1 wt%Te02, the optimum values of da 212 pC/N, d33`g33= 9.54 pm2/N, and kp= 0.448 were obtained, respectively. The results indicate that the composition ceramics is a promising candidate for energy harvesting devices applications.
Dye-sensitized solar cells (DSSCs) based on titanium dioxide (TiO2) have been extensively studied because of their promising low-cost alternatives to conventional semiconductor based solar cells. DSSCs consist of molecular dye at the interface between a liquid electrolyte and a mesoporous wide-bandgap semiconductor oxide. Most efforts for high conversion efficiencies have focused on dye and liquid electrolytes. However, interface engineering between dye and electrode is also important to reduce recombination and improve efficiency. In this work, for interface engineering, we deposited semiconducting ferroelectric BiFeO3 with bandgap of 2.8 eV on TiO2 nanoparticles and nanotubes. Photovoltaic properties of DSSCs were characterized as a function of thickness of BiFeO3. We showed that ferroelectric BiFeO3-coated TiO2 electrodes enable to increase overall efficiency of DSSCs, which was associated with efficient electron transport due to internal electric field originating from electric polarization. It was suggested that engineering the dye-TiO2 interface using ferroelectric materials as inorganic modifiers can be key parameter for enhanced photovoltaic performance of the cell.
The utilization of a fluoran leuco sensitizer, 2-anilino-6-dibutyl amino-3-methylfluoran (ODB-2), for dye-sensitized solar cells (DSSCs) was investigated through the examination of the adsorption of ODB-2 molecules onto the surfaces of porous titanium dioxide (titania, TiO2) films and the photovoltaic properties of ODB-2-based DSSCs. Despite of the absence of the specific anchoring groups with titania, ODB-2 dye molecules were spontaneously adsorbed onto the titania surfaces because the lactone ring in ODB-2 was opened and changed into the carboxylic acid (-COOH) by releasing protons from the surfaces (TiOH2 +) of titania, which consequently leads to the chemisorption reaction of ODB-2 molecules to the active sites of titania. DSSCs based on ODB-2 exhibited typical photovoltaic properties with an open-circuit voltage (VOC) of 0.19 V, a short-circuit current (JSC) of 0.30 mA·cm-2, a fill factor (FF) of 37%, and a conversion efficiency (PCE) of 0.02%.
Aerosol deposition(AD) coating that enable fabricate films at low temperature have begun to be widely researched for the integration of ceramics as well to realize high-speed deposition rates. For application of ceramic thick film by AD to display and electronic ceramic industry, fabrication of dense structure with a no cracking is required. In this study, to fabricate dense ceramic thick film, the effect of crystal phase of starting powder was investigated. For this study, amorphous and crystalline SiO2 powders were used as starting powders. Two types of SiO2 powders were deposited on glass substrate by AD. In the case of amorphous SiO2 powder, the deposited films had extremely incompact and opaque layer, irrespective of particle size. In contrast to amorphous powder, in the case of crystalline powder, porous structure layer and dense microstructure with no cracking layer were fabricated depending on the particle size. The optimized starting powder size for dense coating layer was 1∼2 μm. The transmittance of film reached a maximum of 76% at 800 nm.
PTCR ceramics of (Ba0.998Sm0.002)TiO3 + 0.001MnCO3 + xSiO2 (x=1, 2, 3, 4, 5, 6 mol%) were fabricated by solid state method. Disk samples of diameter 5 mm and thickness about 1mm were sintered at 1,290℃ for 2 h in reduced atmosphere of 5%H2-95%N2 followed by re-oxidation at 600℃ for 30 min. in 20%O2-80%N2.and their microstructures and electrical properties were investigated with SEM and Multimeter. The color of sintered samples was strongly dependent on SiO2 content showing that the color of samples with SiO2 of 1∼2 mol% was gray but that of samples with SiO2 of 4∼6 mol% was changed from gray to blue, which seems to be related with the reduction of samples due to the oxygen vacancies created during the sintering in reduced atmosphere. SiO2 content had a great influence on the microstructure and the electrical properties. With increasing SiO2 content, the grain size of samples increased and the resistivity as well as the resistivity jump (R285/Rmin) decreased, which is considered to be attributed to the resistivity change at grain interior and grain boundary due to the fast mass transfer through SiO2 liquide phase during the sintering. Samples with 2 mol% SiO2 has the resistivity of 202 Ω cm and the resistivity jump of 3.28. It is expected that SiO2 doped BaTiO3 based PTC ceramics can be used for multilayered PTC thermistor due to the resistance to the sintering in reduced atmosphere.
The effect of Cu coating on the sensing properties of nano SnO2:Cu based sensors for the CH4, CH3CH2CH3 gas was studied. This work was focussed on investigating the change of sensitivity of nano SnO2:Cu based sensors for CH4, CH3CH2CH3 gas by Cu coating. Nano sized SnO2 powders were prepared by solution reduction method using stannous chloride(SnCl2·2H2O), hydrazine(N2H2) and NaOH and subsequent heat treatment. XRD patterns showed that nano SnO2 powders with rutile structure were grown with (110), (101), (211) dominant peak. The particle size of nano SnO2:Cu powders at 8 wt% Cu was about 50 nm. SnO2 particles were found to contain many pores, according to SEM analysis. The sensitivity of nano SnO2:Cu based sensors was measured for 5 ppm CH4 gas and CH3CH2CH3 gas at room temperature by comparing the resistance in air with that in target gases. The sensitivity for both CH4 and CH3CH2CH3 gases was improved by Cu coating on the nano SnO2 surface. The response time and recovery time of the SnO2:Cu gas sensors for the CH4 and CH3CH2CH3 gases were 18∼20 seconds, and 13∼15 seconds, respectively.
This study is explore the photoelectric conversion change of dye-sensitized solar cells with surface treatment of the conductive substrate. gases of FTO surface treatment were N2, and O2. Treatment conditions of surface were gas flux from 25 sccm to 50 sccm and RF power were from 25 W to 50 W. Treatment time and pressure were fixed 5 min and 100 mtoor. The best sheet resistance and surface roughness were obtained by O2 50 sccm and 50 W and that result were 7.643 Ω/㎠ and 17.113 nm, respectively. The best efficiency result was obtained by O2 50 sccm and 50 W and that result of Voc, Jsc, FF and efficiency were 7.03 V, 14.88 mA/㎠, 63.75% and 6.67%, respectively.
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