The characteristics of each address discharge were investigated when the voltages of the scan and common electrodes were lowered simultaneously during an address period under the same address voltage conditions in an AC plasma display panel. It was confirmed that the delay time of address discharge shortened as the voltage decreased. However, the background light increased because the low scanning voltage generated more discharge between the electrodes of the upper and lower plates in the reset period. To lower the background light, a positive voltage was applied to the address electrode of the lower panel during the period when the rising ramp wave was applied, and a floating voltage was applied to the address electrode during the period when the falling ramp wave was applied during the reset period. As a result, the background light could be lowered by about 30%.

Titanium dioxide (TiO₂) holds significant scientific and technological relevance as a key photocatalyst and resistive random-access memory, demonstrating unique physicochemical properties and serving as an n-type semiconductor. Understanding the density and arrangement of oxygen vacancies (VOs) is crucial for tailoring TiO₂’s properties to diverse technological needs, driving increased interest in exploring oxygen vacancy complexes and superstructures. In this mini review, we summarize the recent understandings of the fundamental properties of oxygen vacancies in bulk rutile (R-TiO₂) and anatase (A-TiO₂) based on DFT and beyond method. We specifically focus on the excess electrons and their spatial arrangement of disordered single VO in bulk R and A-TiO₂, aligned with the experimental findings. We also highlight the theoretical works on investigating the geometries and stabilities of ordered VOs complexes in bulk TiO₂. This comprehensive review provides insights into the fundamental properties of excess electrons in reduced TiO₂, offering valuable perspectives for future research and technological advancements in TiO₂-based devices.

We fabricated BiAlO thin film by a solution process with a brush coating to be used as liquid crystal (LC) alignment layer. Solution-processed BiAlO was coated on the glass substrate by brush process. Prepared thin films were annealed at different temperatures of 80℃, 180℃, and 280℃. To verify whether the BiAlO film was formed properly, X-ray photoelectron spectroscopy analysis was performed on Bi and Al. Using a crystal rotation method by polarized optical microscopy, LC alignment state was evaluated. At the annealing temperature of 280℃, the uniform homogenous LC alignment was achieved. To reveal the mechanism of LC alignment by brush coating, field emission scanning electron microscope was used. Through this analysis, spin-coated and brush coated film surface were compared. It was revealed that physical anisotropy was induced by brush coating at a high annealing temperature. Particles were aligned in one direction along which brush coating was made, resulting in a physical anisotropy that affects a uniform LC alignment. Therefore, it was confirmed that brush coating combined with BiAlO thin film annealed at high temperature has a significant potential for LC alignment.

In this study, the dielectric properties of flame retardant silicone rubber mixed with the amount of silica 50~65 phr were measured at frequencies ranging from 1 to 2.7 MHz and temperature ranges from 30℃ to 160℃. The permittivity decreased with higher frequencies and higher temperatures, and tanδ are thought to have decreased due to the increased heat oxidation of the methyl group bound to Si, which increased the hardness of silicone rubber. FT-IR analysis of specimen mixed with SiO₂ of 50~65 phr showed oscillations of OH groups bound to SiO₂ between wavenumber 3,600 and 3,300. As a result of analyzing surface components by Energy Dispersive X-ray (EDX) on all specimens mixed with SiO₂ of 50 to 65 phr, all specimens contained Si, and the analysis by field emission scanning electron (FE-SEM) confirmed that about 1~5 μm particles were distributed regularly on the surface of the specimens.

High reliability thin film transistors are important factors for next-generation displays. The reliability of transparent a-IGZO semiconductors is being actively studied for display applications. A plasma treatment can fill the oxygen vacancies in the channel layer and the channel layer/insulating layer interface so that the device can work stably under a bias voltage. This paper studies the effect of plasma treatment on the performance of a-IGZO TFT devices. The influence of different plasma gases on the electrical parameters of device and its working reliability are reviewed. The article mentions argon, fluorine, hydrogen and several ways of processing in the atmosphere. Among these methods, F (fluorine) plasma treatment can maximize equipment reliability. It is expected that the presented results will form a basis for further research to improve the reliability of a-IGZO TFT.

A linear piezoelectric actuator that utilizes the elliptical motion of the two tips of the actuator is proposed. This device is easy to fabricate owing to its simple structure, consisting of three piezo ceramic benders and is suitable for use in micro robotic applications. A π-shaped structure, which was composed of four piezo ceramic benders, was constructed. Two of the benders were positioned on the center of the actuator, and the joints were attached at the ends of the cantilever. The other two benders were positioned on the side of the actuator and were attached between the joint and the tips. The actuator structure was designed to obtain the first bending mode of the horizontal vibration and the vertical vibration at the same frequency, resulting in elliptical motions at the tips. When two sinusoidal wave voltages with a 90-degree phase difference were applied to the two pairs of the actuator benders, elliptical motions were obtained at the tips. The driving characteristics of the prototype actuator were then measured using a laser doppler vibrometer.

An 80 nm thick zinc aluminate thin film was deposited on a glass substrate via radio-frequency (rf) magnetron sputtering and heat treated to analyze changes in the wetting angles due to a surface modification. The thin films were modified from hydrophilic to hydrophobic by a simple thermal treatment. The surface modification from a heat treatment increased the wetting angles up to 111°, which was explained by the relationship with the excess surface area. The wetting angles of the annealed thin films decreased with increasing exposure time under ambient conditions, which was attributed to the oxygen vacancies in the films that were introduced during deposition. The annealed thin films were treated by ionized oxygen via oxygen plasma. After the oxygen plasma treatment, the decreased wetting angles were maintained at ~95° for 11 days.

A fire, be it caused intentionally or unintentionally, leads to economic loss and physical damage, and requires digestion. The number of fires is increasing yearly, and electrical fires account for more than 30% among the main causes of fires. Electric wires that catch fire typically employ silicone coatings; silicone has organic as well as inorganic properties. Silicon is a natural, nonexistent, synthetic product with numerous applications. In this study, a silicon rubber for application in wires was prepared by high-temperature vulcanization (HTV) with a Shore A hardness of 70. We report results for the flame retardancy test and the fire safety characteristics via inorganic analysis. For this, a quartz inorganic material was added to the wire specimen, and 18% powdered extinguishing agent ammonium phosphate and expanded vermiculite respectively. Thus, expanded vermiculite showed the best flame retardancy and fire safety characteristics.

In this study, a high-temperature vulcanizing (HTV) method was used to achieve a shore a hardness of 70. The basic base was composed of 60% silicon gum (GUM) which is a high-viscosity polymer, 30% fumed silica (FS), and 5% of plasticizer. The GUM and FS were mixed well with less than 1% silane to improve rubber strength. Expanded vermiculite was added as a filler at 10%, 15%, and 20%. The curing conditions were 170℃ for 10 min and a molding method was applied. We report herein, the results of inorganic analysis and flame-retardant and tracking tests on the expanded vermiculite. The flame retardance and tracking test outcomes for a shore a hardness of 70 were found to be optimal when the expanded vermiculite content was 10%.

Energy harvesting characteristics of trapezoidal piezoelectric cantilever generator, which has a lead zirconate titanate (PZT) laminate film, were compared by longitudinal (3-3) and transverse (3-1) modes. The PZT laminate film, fabricated by a conventional tape casting process, was cofired with Ag electrode at 850℃ for 2 h. A multi-layered Ag electrode by a planar pattern and an interdigitated pattern was applied to the PZT laminate to implement the 3-3 and 3-1 modes, respectively. The energy harvesting performance of the 3-3 mode trapezoidal piezoelectric cantilever generator was better than that of the 3-1 mode. An extremely high output power density of 26.7 mW/cm³ for the 3-3 mode was obtained at a resonant frequency of 145 Hz under a load resistance of 50 ㏀ and acceleration of 1.3 G, which is ~3-times higher than that for the 3-1 mode. Therefore, the 3-3 mode is considered significantly efficient for application to high-performance piezoelectric cantilever generator.

A unimorph piezoelectric cantilever generator with an interdigitated electrode (IDE) was developed for vibration energy harvester applications driven in the longitudinal mode. Hard lead zirconate titanate (PZT) ceramic with a high Q_m of 1,280 was used as the piezoelectric active material. Ten PZT sheets produced by tape casting were laminated and co-fired with an Ag/Pd IDE at 1,050℃ for 2 h. The approximately 280 μm-thick co-fired PZT laminate with the IDE was attached to a stainless steel substrate with an adhesive epoxy for the fabrication of an IDE unimorph cantilever. Its energy harvesting characteristics were evaluated: an output power of 1.1 μW at 120 Hz across the resistive load of 700 k□ was obtained, corresponding to a normalized power factor of 4.1 μW/(G²·cm³).

The effect of low temperature (250℃) heat treatment after electron irradiation (irradiation time = 30, 180, 300s) on the chemical bonding and electrical properties of ZnO thin films prepared using a sol-gel process were examined. XPS (X-ray photoelectron spectroscopy) analysis showed that the electron beam irradiation decreased the concentration of M-O bonding and increased the OH bonding. As a result of the electron beam irradiation, the carrier concentration of ZnO films increased. The on/off ratio was maintained at ~10⁵ and the VTH values shifted negatively from 11 to 1 V. As the irradiation time increased from 0 to 300s, the calculated S. S. (subthreshold swing) of ZnO TFTs increased from 1.03 to 3.69 V/decade. These values are superior when compared the sample heat-treated at 400℃ representing on/off ratio of ~10² and S. S. value of 10.40 V/decade.

ZnO nanorods were grown on SiO2 coated Si wafers and glass by the hydrothermal method. The structural and optical properties variation of ZnO nanorods as a function of growing time was studied. ～10 nm-thick ZnO thin films deposited on substrates by rf magnetron sputtering were employed as seed layers. Zinc nitrate hexahydrate (0.05 M) and hexamethylenetetramine (0.05 M) mixed in DI water were used as a reaction solution. ZnO nanorods were respectively grown for 30 min, 1 h, 2 h, 3 h, and 4 h by maintaining the reactor at 90℃. Crystallinity of ZnO nanorods was analyzed by X-ray diffraction, and the morphology of nanorods was observed by a field emission scanning electron microscope. Transmittance and absorbance were measured by a UV-Vis spectrophotometer, and energy band gap and urbach energy were obtained from the data. Photoluminescence measurements were carried out using Nd-Yag laser (266 nm).

The conduction behavior and electron concentration change in a-IGZO thin-films according to the RTA (rapid thermal annealing) were studied. The electrical characteristics of TFTs (thin-film-transistors) annealed by different temperatures were measured. The sheet resistance, electron concentration, and oxygen vacancy of a-IGZO film were measured by the four-point-probe-measurement, hall-effect-measurement, and XPS analysis. The RTA process increased the driving current of IGZO TFTs but the VTH shifted to the negative direction at the same time. When the RTA temperature is higher than 250℃, the leakage current at off-state increased significantly. This is attributed to the increase of oxygen vacancy resulting in the increase of electron concentration. We demonstrate that the RTA is a promising process to adjust the VTH of TFT because the RTA process can easily modify the electron concentration and control the conductivity of IGZO film with short process time.

For the measurements of surface shape milled using FIB (focused ion beam), the silicon bulk,Si3N4/Si, and Al/Si samples are used and observed the shapes milled from different sputtering rates,incident angles of Ga+ ions bombardment, beam current, and target material. These conditions also can beinfluenced the sputtering rate, raster image, and milled shape. The fundamental ion-solid interactions ofFIB milling are discussed and explained using TRIM programs (SRIM, TC, and T-dyn). The damagedlayers caused by bombarding of Ga+ ions were observed on the surface of target materials. The simulatedresults were shown a little bit deviation with the experimental data due to relatively small sputtering rateon the sample surface. The simulation results showed about 10.6% tolerance from the measured data at200 pA. On the other hand, the improved analytical model of damaged layer was matched well withexperimental XTEM (cross-sectional transmission electron microscopy) data.

We have investigated the structural and electrical properties of Si-Zn-Sn-O (SZTO) thin filmsdeposited by RF magnetron sputtering at various deposition temperatures from RT to 350℃. All theSZTO thin fims are amorphous structure. The mobility of SZTO thin film has been changed dependingon the deposition temperature. SZTO thin film transistor shows mobility of 8.715 ㎠/Vs at roomtemperature. We performed the electrical stress test by applying gate and drain voltage. SZTO thin filmtransistor shows good stability deposited at room temperature while showing poor stability deposited at350℃. As a result, the electrical performance and stability have been changed depending on depositiontemperature mainly because high deposition temperature loosened the amorphous structure generatingmore oxygen vacancies.

In this paper, we prepared Cu(In,Ga)Se2 thin films by using co-evaporation method, and analyzed the properties of the thin films. During the thin film preparation process, we confirmed InGaSe2 phase was formed at 400℃ in first stage, and also confirmed the thin films showed the vacancy decrease. In second and third stage,we confirmed the density increase of crystalline structure at over 480℃ and the formation of Cu(In0.7Ga0.3)Se2phase. As the result of SEM and XRD analysis of the films which were before and after heat-treated, we confirmed the disappearance of Cu2Se2 and the formation of Cu(In0.7Ga0.3)Se2 single phase after the heat-treatment,We, therefore, confirmed the heat-treatment did not affect the absorbency spectra of the thin films.

In this study, we fabricated a micro Pb(Zr,Ti)O3 (PZT) film piezoelectric cantilever with a Si proof mass and dual beams through MEMS process. The size of the beam and the integrated Si proof mass were about 4,320 μm × 290 μm × 12 μm and 1,380 μm × 880 μm × 450 μm each. To reduce the air damping and have the larger displacement of dual beams was used for design. After mounting micro PZT film piezoelectric cantilever on shaker, we measured the resonance frequency and a output voltage while making resonant frequency changed. The resonant frequency and the highest average power of the cantilever device were 110.2 Hz and 0.36 μW each, at 0.8 g acceleration and 23.7 kΩ load resistance,respectively.

This paper dealt with the development of a LED floodlight for naval vessels to replace the conventional floodlight using an incandescent and a halogen lamp. We found a technical solution for current problems of conventional lights and also improved optical characteristics by developing a LED floodlight which has a typical long-lived light source with high efficiency. To satisfy the requirements specified in Korea Standard Vessels (KS V), the optical structure was designed with selected LED package and lens. A LED module was composed of 10 LEDs in series for stable luminous output, and an aluminium heat sink was adopted for effective heat-radiation design. The LED floodlight was fabricated as a module type so that it can easily replace the conventional light source. The power consumption of the prototype floodlight was only a tenth of a conventional one with the same optical performance. Also, a test showed the floodlight satisfied the electrical, optical and environmental requirements of the standards.

We fabricated piezoelectric unimorph cantilever generators (UCG) using Pb(Zr0.54Ti0.46)O3 + 0.2 wt% Cr2O3 + 1.0 wt% Nb2O5 (PZCN) piezoelectric thick films, which were produced by a tape casting method. The PZCN thick films were tailored with same width and thickness but different lengths from 7.7 to 57.7 mm in order to evaluate optimized UCG for energy harvesting device applications. When the length of PZCN film was increased, the resonance frequency of UCG was slightly increased from 7 Hz to 8 Hz, which could be due to enlarged area of the highly stiff piezo-ceramic film. However, the output power was proportionally increased with the length of PZCT film and it reached 4.68 mW (1.221 mW/cm3) when the film`s length was 57.7 mm under 25 g of tip mass at 8 Hz, which is sufficient for micro-scale device applications.

This research measured the dielectric properties of silicone rubber with various hardness in 100 Hz∼3 MHz, 30∼170℃ conditions. When the hardness increases from 65 degree to 75 degree, the dielectric loss increased within frequency range of 100 kHz～3 MHz and was a little change in dielectric loss within temperature range of 90℃～170℃. Thermogravimetric Analysis (TGA) showed the weight change rate increased a little while heated until 800℃. Scanning Electron Microscope (SEM) measurement showed that Aluminium Trihydroxide(AlOH3) which acts as a reinforcement agent reduced the size of the particles as the hardness increased.

Spring supported piezoelectric cantilever structures (SPCS) were fabricated for vibration-based energy harvester application. We selected four elastic springs (A, B, C, and D type) as cantilever`s supporter, each elastic spring has a different spring constant (S). The C type of SPCS (SC: 4,649 N/m) showed a extremely low resonance frequency of 81 Hz along with the highest power output of 38.5 mW while the A type of SPCS (SA: 40,629 N/m) didn`t show a resonance frequency while. Therefore, it is considered that the lower spring constant lead to a lower resonance frequency of the SPCS. In addition, a tip mass (18 g) at one end of the SPCS could further reduce the resonance frequency without heavy degradation of power output.

A road energy harvester was designed and fabricated to convert mechanical energy from the vehicle load to electrical energy. The road energy harvester is composed of 16 piezoelectric cantilevers. We fabricated prototypes using a vehicle load transfer mechanism. Applying a vehicle load transfer mechanism rather than directly installing energy harvesters under roads decreases the area of road construction and allows more energy harvesters to be installed on the side of the road. The power generation amount with respect to the vehicular velocity change was assessed by installing the vehicle load transfer mechanism form and underground form. The energy harvester installed in the underground form generated power of 4.52mJ at the vehicular velocity of 50 km/h. Also, power generation of the energy harvester installed in the vehicle load transfer mechanism form was 48.65mJ at the vehicular velocity of 50 km/h.

A road energy harvester was designed and fabricated to convert mechanical energy from the vehicle load to electrical energy. The road energy harvester is composed of 24 piezoelectric cantilevers and a vehicle load transfer mechanism. Applying a vehicle load transfer mechanism rather than directly installing energy harvesters under roads decreases the area of road construction and allows more energy harvesters to be installed on the side of the road. The power generation amount with respect to the vehicular velocity change was assessed by installing the vehicle load transfer mechanism and the energy harvester in the form of speed bumps and underground. The energy harvester installed in a speed bump form generated power of 7.61 ㎽at the vehicular velocity of 20 km/h. Also, power generation of the energy harvester installed in the underground form was 63.9 ㎽at the vehicular velocity of 28 km/h. Although the number of piezoelectric cantilevers was reduced by 1/3 to 24 in comparison to the previous research results with 72 piezoelectric cantilevers, similar power generation characteristic value was obtained within the vehicular velocity of 20 km/h by altering the vehicle load transfer mechanism and cantilever vibration method.

In this study, Ge8Se(2+x)Te(6-x) thin film amorphous-to-crystalline phase-change rate was evaluated in using a nano-pulse scanner. The focused laser beam with a diameter <10 μm was illuminated in the power (P) and pulse duration (t) ranges of 1-31 mW and 10-460 ns, respectively, with subsequent detection of the responsive signals reflected from the film surface. We also evaluated the material characteristics, such as optical absorption and energy gap, crystalline phases, and sheet resistance of as-deposited and annealed films. The result of experiments showed that the thermal stability of the Ge-Se-Te film is largely improved by adding Se.

A cantilever-type piezoelectric generator has advantages of simple structure, ease of fabrication and large displacement by transverse vibration of a beam. It is easy to control the natural frequency, and also possible to increase the output power by changing the length, width, and thickness of the generator. In particular, the length increases, the natural frequency sharply decreases, and vice versa. Hence, the natural frequency can widely be controlled by using change in the length of elastic body. In this paper, the generator was designed and fabricated to change natural frequency using the slides of the case. In addition, the generating characteristics were confirmed through finite element analyses and vibration experiment. As a result, the maximum output characteristics could be generated due to resonance phenomenon although any frequency of external force was applied.

Piezoelectric energy harvester (PEH) as a box type was fabricated in order to harvest mechanical energy imparted to roadways from passing vehicles and convert it into electricity. The PEH was composed of 72 piezoelectric cantilevers with 9 springs with elasticity stick to a bottom of the PEH. For the single piezoelectric cantilever, when a single push with approximately 5 mm displacement was incident to it, power of 0.355 mW was produced at 100 kΩ. It is found that the power from the single piezoelectric cantilever increases when spring constant is high. We investigated power of PEH when the moving vehicle passes in it. Power was increased with increasing vehicle speed. When vehicle speed is 30 km/h, power is 20.6 mW.

In this work, we designed and fabricated a multilayer thin film Pb(Zr,Ti)O(3) cantilever with a Si proof mass for low frequency vibration energy harvesting applications. A mathematical model of a multi-layer composite beam was derived and applied in a parametric analysis of the piezoelectric cantilever. Finally, the dimensions of the cantilever were determined for the resonant frequency of the cantilever. We fabricated a device with beam dimensions of about 4,930 μm × 450 μm × 12 μm, and an integrated Si proof mass with dimensions of about 1,410 μm × 450 μm × 450 μm. The resonant frequency, maximum peak voltage, and highest average power of the cantilever device were 84.5 Hz, 88 mV, and 0.166 μWat 1.0 g and 23.7 Ω, respectively. The dimensions of the cantilever were determined for the resonance frequency of the cantilever.

Abstract: The porous Si (PS) was annealed at various temperature in air, argon, and nitrogen atmosphere. Structural and optical properties of the annealed PS were investigated by scanning electron microscopy (SEM) and photoluminescence (PL). It is found that the shape of pore is changed from circle to channel as increasing annealing temperature which was annealed in air and argon atmosphere. In case of PS annealed in nitrogen atmosphere, the shape of pore is changed from channel to circle with increase annealing temperature from 600 to 800℃. The PL peak position is blue-shifted with increasing annealing temperature. As annealing temperature increases, the PL intensity of the PS annealed in argon is decreased but that of the PS annealed in nitrogen is increased. It might be due to the formation of Si-N bonds and it passivates the non-radiative centers which is Si dangling bonds on the surface of the PS.