This work investigates the effect of γ-Al2O3 additives on the CCD properties of Li6.5La3Zr1.5Ta0.5 O12 (LLZTO) solid electrolyte ceramics. LLZTO with large grains, optimized under the conditions of doping composition, sintering temperature, atmosphere, and crucible, exhibited a high relative density of over 98

We aimed to fabricate reliable memory devices using HfO2, which is gaining attention as a charge-trapping layer material for next-generation NAND flash memory. To this end, a new atomic layer deposition process using sequential remote plasma (RP) and direct plasma (DP) was designed to create charge-trapping memory devices. Subsequently, the operational characteristics of the devices were analyzed based on the thickness ratio of thin films deposited using the sequential RP and DP processes. As the thickness of the initially RP-deposited thin film increased, the memory window and retention also increased, while the interface defect density and leakage current decreased. When the thickness of the RP-deposited thin film was 7 nm, a maximum memory window of 10.1 V was achieved at an operating voltage of ±10 V, and the interface trap density (Dit) reached a minimum value of 1.0 × 1012 eV−1cm−2. Once the RP-deposited thin film reaches a certain thickness, the ion bombardment effect from DP on the substrate is expected to decrease, improving the Si/SiO2/HfO2 interface and thereby enhancing device endurance and reliability. This study confirmed that the proposed sequential RP and DP deposition processes could resolve issues related to unstable interface layers, improve device performance, and enhance process throughput.

Plasma-enhanced atomic layer deposition (ALD) is a common method for fabricating Hf0.5Zr0.5O2 (HZO) ferroelectric thin films that can be performed using direct-plasma (DP) and remote-plasma (RP) methods. This study proposed co-plasma ALD (CPALD), where DPALD and RPALD are applied simultaneously. HZO films fabricated using this method showed wake-up-free polarization properties, no anti-ferroelectricity, and high fatigue endurance when DPALD and RPALD started simultaneously. To minimize defects in the film that could negatively affect the low polarization properties and fatigue endurance, the direct plasma power was reduced to 75 W. Thus, excellent fatigue endurance for at least 109 cycles was obtained under a high total remanent polarization of 47.3 μC/cm2 and an applied voltage of 2.5 V. X-ray photoelectron spectroscopy and transmission electron microscopy were used to investigate the mechanisms responsible for these properties. The HZO films fabricated by CPALD contained few lattice defects (such as nonstoichiometric hafnium, nonlattice oxygen, and residual carbon) and no paraelectric phase (m-phase). This was attributed to the low-carbon residuals in the film, as high-energy activated radicals were supplied by the adsorbed precursors during film formation. This facilitated a smooth transition to the o-phase during heat treatment, which possessed ferroelectric properties.

To develop plasma-resistant glass materials suitable for semiconductor etching processes, we introduced alkaline earth oxides (ROs) into a Li2O–Al2O3–SiO2 (LAS) glass. Analysis of glass properties with respect to the additives revealed that among the analyzed materials, the LAS material in which Li2O was partially replaced by MgO (MLAS) exhibited the most favorable characteristics, including a low dielectric constant (6.3) and thermal expansion coefficient (2.302 × 10−6/°C). The high performance of MLAS is attributed to the high ionic field strength of Mg2+ ions, which restricts the movement of Li+ ions under the influence of electric fields and thermal vibrations at elevated temperatures. When exposed to CF4/O2/Ar plasma, the etching speed of RO-doped glasses decreased compared with that of quartz and LAS glass, primarily owing to the generation of a high-sublimation-point fluoride layer on the surface. Herein, MLAS demonstrated the slowest etching speed, indicating exceptional plasma resistance. X-ray photoelectron spectroscopy analysis conducted immediately after plasma etching revealed that the oxidation-to-fluorination ratio of Li was the lowest for MLAS. This observation suggests that the presence of Mg2+ ions in the plasma discharge inhibits the migration of Li+ ions toward the surface, thereby contributing to the excellent plasma resistance of MLAS.

ZnO is one of the most widely used inorganic sunscreens, owing to its fine particle size and UV light shielding capability. However, powders at nanosizes can be toxic and cause adverse effects. The development of non-nanosized particles has been slow. The present work investigated synthesis methods of non-nanosized ZnO particles for ultraviolet protection application. By altering the starting material, KOH concentration, and input speed, the ZnO particles can be obtained in different forms, including needle type, planar type, and vertical wall type. Cosmetic samples were made by mixing different ratios of synthesized powders. The physical properties and the UV blockage efficacy of different samples were evaluated using scanning electron microscopy (SEM), X-ray diffraction (XRD), particle size analyzer (PSA), and ultraviolet/visible (UV/Vis) spectrometer. The samples with 1:1 ratio of needle-type ZnO and vertical wall-type ZnO exhibited superior light blocking effect owing to improved dispersibility and prevention of particle agglomeration. The 1:1 mixed sample also complied with the European nanomaterials regulation due to the absence of nanosized particles. With superior UV protection in the UVA and UVB regions, the 1:1 mixed powder showed potential to be used as a main ingredient in UV protection cosmetics.

Hf0.5Zr0.5O2 (HZO) thin film exhibits ferroelectric properties and is presumed to be suitable for use in next-generation memory devices because of its compatibility with the complementary metal–oxide–semiconductor (CMOS) process. This study examined the physical and electrical properties of HZO thin films deposited by two plasma-enhanced atomic layer deposition (PEALD) methods— direct plasma atomic layer deposition (DPALD) and remote plasma atomic layer deposition (RPALD)—and the effects of plasma application on the properties of HZO thin films. The initial conditions for HZO thin film deposition, depending on the RPALD deposition temperature, were established based on previous research on HZO thin films deposited by the DPALD method. The results show that as the measurement temperature increases, the electric properties of DPALD HZO quickly deteriorate; however, the RPALD HZO thin film exhibited excellent fatigue endurance at a measurement temperature of 60 °C or less. HZO thin films deposited by the DPALD and RPALD methods exhibited relatively good remanent polarization and fatigue endurance, respectively. These results confirm the applicability of the HZO thin films deposited by the RPALD method as ferroelectric memory devices.

Optimization of equipment structure and process conditions is essential to obtain thin films with the required properties, such as film thickness, trapped charge density, leakage current, and memory characteristics, that ensure reliability of the corresponding device. In this study, we fabricated metal–insulator–semiconductor (MIS) structure capacitors using HfO2 thin films separately deposited by remote plasma (RP) atomic layer deposition (ALD) and direct-plasma (DP) ALD and determined the optimal process temperature by measuring the leakage current and breakdown strength as functions of process temperature. Additionally, we analyzed the effects of the plasma application method on the charge trapping properties of HfO2 thin films and properties of the interface between Si and HfO2. Subsequently, we synthesized charge-trapping memory (CTM) devices utilizing the deposited thin films as charge-trapping layers (CTLs) and evaluated their memory properties. The results indicated excellent memory window characteristics of the RP-HfO2 MIS capacitors compared to those of the DP-HfO2 MIS capacitors. Moreover, the memory characteristics of the RP-HfO2 CTM devices were outstanding as compared to those of the DP-HfO2 CTM devices. In conclusion, the methodology proposed herein can be useful for future implementations of multiple levels of charge-storage nonvolatile memories or synaptic devices that require many states.

Other SectionsAbstractINTRODUCTIONSUBJECTS AND METHODSRESULTSDISCUSSIONACKNOWLEDGEMENTSCONFLICT OF INTERESTAUTHOR CONTRIBUTIONSFUNDINGReferences

HfxZr1−xO2 (HZO) thin films have excellent potential for application in various devices, including ferroelectric transistors and semiconductor memories. However, such applications are hindered by the low remanent polarization (Pr) and fatigue endurance of these films. To overcome these limitations, in this study, HZO thin films were fabricated via plasma-enhanced atomic layer deposition (PEALD), and the effects of the deposition and post-annealing temperatures on the density, crystallinity, and electrical properties of the thin films were analyzed. The thin films obtained via PEALD were characterized using cross-sectional transmission electron microscopy images and energy-dispersive spectroscopy analysis. An HZO thin film deposited at 180 °C exhibited the highest o-phase proportion as well as the highest density. By contrast, mixed secondary phases were observed in a thin film deposited at 280 °C. Furthermore, a post-annealing temperature of 600 °C yielded the highest thin film density, and the highest 2Pr value and fatigue endurance were obtained for the film deposited at 180 °C and post-annealed at 600 °C. In addition, we developed three different methods to further enhance the density of the films. Consequently, an enhanced maximum density and exceptional fatigue endurance of 2.5 × 107 cycles were obtained.

To achieve good long-term temperature stability in devices used in energy-conversion applications, this study is aimed at developing combined ceramics, referred to as PZN-PMN-PZT, comprising Pb(Zn1/3Nb2/3)O3 (PZN) and Pb(Mn1/3Nb2/3)O3 (PMN), which are typical relaxor ferroelectric materials, and Pb(Zr,Ti)O3 (PZT). The piezoelectric properties were compared based on several parameters according to the change in the composition ratio between relaxor materials, amounts of Sb2O3 dopant, and Zr/Ti ratio in the PZT system. Finally, we established optimal poling conditions to improve the electrical properties of the optimized piezoelectric material, based on the evaluation of ceramic properties according to the applied voltage during the poling process. The optimized composition of the investigated piezoelectric ceramics is represented by 0.14PZN-0.06PMN-0.80PbZr0.49Ti0.51 + 0.3 wt.% CuO + 0.3 wt.% Fe2O3 with 0.1 wt.% Sb2O3 doping, which yielded the superior properties (d33 = 361 pC/N, Qm = 1234, Tc = 306 °C).

Piezoelectric material properties were optimized to develop materials for an ultrasonic vibrator targeting a high vibration efficiency. Herein, novel materials were developed using a composition represented by 0.08Pb(Ni1/3Nb2/3)O3-0.07Pb(Mn1/3Nb2/3)O3-0.85Pb(Zr0.5Ti0.5)O3 + 0.3 wt.% CuO + 0.3 wt.% Fe2O3 with 0.3 wt.% Sb2O3 doping. A ceramic shape with a thickness of 2 mm was optimized using finite element analysis software, and high values of coupling factors (0.54) and mechanical quality factors (1151) were obtained. This ceramic was used to fabricate a bio-beauty device (frequency = 1 MHz), and the manufactured ultrasonic vibrator indicated that the actuator oscillated with the maximum amplitude at a frequency of 1.06 MHz.

This study proposed a method for manufacturing nanopatterned molds with high strength and durability using UV-curable polymer nanocomposites. Zirconia (ZrO2) nanoparticles (NPs) were blended with Ormostamp, a commercial UV-curable resin, using the solution blending method. The elastic modulus and hardness of the cured nanocomposite layer were investigated through a nanoindentation test for different volume ratios of NPs in the Ormostamp composite from 0 to 53.8%. The modulus and hardness of pure resin were 0.075 +/- 0.002 GPa and 9.7 +/- 0.164 MPa, respectively, and they increased to 11.9 GPa and 146.9 MPa at an NP concentration of 58.3%. Nanocomposite molds were fabricated by nanoimprinting with a PDMS stamp, which is replicated from the nanodimple array master. The fabricated nanocomposite mold can efficiently replicate other UV-curable resins. Hot embossing was then performed for a PMMA film using the fabricated molds. Unlike a pure UV-curable resin, which showed damage and fracture of the dimple structure after the first replication, the nanocomposites maintained the nanodimple shape even up to 30 replications. Uniform nanopatterns can be formed on even cylindrical surfaces by using a soft replica stamp. Polymer nanocomposites with a high NP concentration exhibited significantly improved mechanical reinforcement when compared to conventional pure polymers for mold making. Therefore, they are expected to be extremely useful for manufacturing nanopatterned molds using UV resin.

Porous films of metals and metal oxides exhibit larger surface areas and higher reactivities than those of dense films. Therefore, they have gained growing attention as potential materials for use in various applications. This study reports the use of a modified direct current magnetron sputtering method to form porous Zn-ZnO composite films, wherein a subsequent wet post-oxidation process is employed to fabricate pure porous ZnO films. The porous Zn-ZnO composite films were initially formed in clusters, and evaluation of their resulting properties allowed the optimal conditions to be determined. An oxygen ratio of 0.3% in the argon gas flow resulted in the best porosity, while a process pressure of 14 mTorr was optimal. Following deposition, porous ZnO films were obtained through rapid thermal annealing in the presence of water vapor, and the properties and porosities of the obtained films were analyzed. An oxidation temperature of 500 °C was optimal, with an oxidation time of 5 min giving a pure ZnO film with 26% porosity. Due to the fact that the films produced using this method are highly reliable, they could be employed in applications that require large specific surface areas, such as sensors, supercapacitors, and batteries.

In this study, a [0001]-plane planar-type ZnO ceramic powder material with a high aspect ratio ranging from 20:1-50:1 is synthesized using the electrolyte collected from zinc air battery power generation. This high aspect ratio may be due to the Zn(OH)2-₄ anion dissolved in the electrolyte. The obtained planar-type ZnO exhibits excellent formulation stability and applicability, even when formulated as a cosmetic with a single inorganic ingredient. Compared to commercial ZnO or TiO₂ powders, relatively better protection against infrared and ultraviolet (UV) radiation is realized due to its asymmetric characteristics, with a width of approximately 1 μm and thickness of tens of nm. The synthesized planar-type ZnO is mixed with nanosized ZnO or TiO₂ commercial powders and formulated into various combinations to achieve a high UV protection rate and heat-blocking effect. In particular, the addition of planar-type ZnO to nanosized TiO₂ powders increases the heat-blocking effect, and improves the applicability and formulation stability of the cosmetic formulation, despite the decrease in turbidity. Among all the ceramic powder combinations examined in this study, the best UV protection rate and heat-blocking effect are obtained when the synthesized planar-type ZnO is mixed with microsized and nanosized TiO₂.

The rapidly growing Li-ion battery market has generated considerable demand for Li-ion batteries with improved performance and stability. All-solid-state Li-ion batteries offer promising safety and manufacturing enhancements. Herein, we examine the effect of substitutional doping at three cation sites in garnet-type Li7La3Zr2O12 (LLZO) oxide ceramics produced by a sol–gel synthesis technique with the aim of enhancing the properties of solid-state electrolytes for use in all-solid-state Li-ion batteries. Building on the results of mono-doping experiments with different doping elements and sites—Al, Ga, and Ge at the Li+ site; Rb at the La3+ site; and Ta and Nb at the Zr4+ site—we designed co-doped (Ga, Al, or Rb with Nb) and tri-doped (Ga or Al with Rb and Nb) samples by compositional optimization, and achieved a LLZO ceramic with a pure cubic phase, almost no secondary phase, uniform grain structure, and excellent Li-ion conductivity. The findings extend the current literature on the doping of LLZO ceramics and highlight the potential of the sol–gel method for the production of solid-state electrolytes.

To classify 2.5-µm-scale fine dust and measure its concentration, research was conducted to produce a fine-dust sensor utilizing computational fluid dynamics simulation and microelectromechanical system processes, and the measurement system was manufactured for the sensor. The virtual impactor was designed to classify particles in the air above and below 2.5 µm, and the cut-off diameter of 2.5 µm at an acceleration nozzle length of 83.2 µm was obtained by verifying this impactor through flow-analysis simulation. The microheater was then designed to measure the mass of the classified particle by adsorbing it onto the surface acoustic wave resonator placed on the lower part of the flow channel using thermophoretic force. The conditions where the classified particles are completely adsorbed on the surface acoustic wave resonator through the heater were calculated using numerical modeling and the results were verified through the simulation. The fine dust sensor based on the designed surface acoustic wave resonator is composed of the upper, middle, and lower parts including the heater, virtual impactor, and surface acoustic wave resonator and SMA connector, respectively, and the micro-fan controlling the total flow. Each part was produced using the microelectromechanical system process, assembled, and finally finished. Moreover, the evaluation system was produced in this study to assess the developed sensor. The flow of air controlled through the flowmeter was sprayed into a dust bottle filled with hollow silica powder to scatter the powder, which flowed into the system with the air, making the environment similar to one with fine dust present. The change in radio-frequency resonance characteristics, such as those before and after exposure to the fine dust environment, and insertion loss after the surface cleaning were observed, and a sensitivity of, detection limit of, and restoration rate after surface cleaning exceeding 99.9% were obtained.

A multilayer piezoelectric material was fabricated using piezoelectric materials with low-temperature sintering capabilities and high piezoelectric coefficients to develop a functionally superior piezoelectric speaker with a large-displacement deformation. A soft relaxor was utilized to prepare the component materials, with the optimized composition of the investigated piezoelectric ceramics represented by 0.2Pb((Zn0.8Ni0.2)13Nb23)O3−0.8Pb(Zr0.5Ti0.5)O3. Li2CO3 was added to assist the low-temperature sintering conducted at 875 °C, which yielded a multilayer piezoelectric material with superior properties (d33 = 500 pC N−1, kp = 0.63, g33 = 44 mV N−1). A multilayer piezoelectric actuator with a single-layer thickness of ~40 µm and dimensions of 12 × 16 mm2 was fabricated by tape casting the prepared green sheets. Finite element analysis revealed that the use of a PEEK film and a smaller silicone–rubber film as a composite in the diaphragm realized optimal frequency-response characteristics; the vibrations generated by the piezoelectric element were amplified. The optimal structure obtained via simulations was applied to fabricate an actual piezoelectric speaker with dimensions of 20 × 24 × 1 mm3. The actual measurements exhibited a sound pressure level of ~75 dB and a total harmonic distortion ≤15% in the audible frequency range (250–20,000 Hz) at an applied voltage of 5 Vp.

본 논문은 니클라스 루만의 ‘체계/환경-차이 이론에 따라, 계층적 분화의 사회질서 원칙과 기능적 분화의 사회질서 원칙의 경합 테제를 출발점으로 하여 한국사회를 분석할 수 있다는 것을 제안한다. 먼저 ‘체계/환경-차이’ 이론은 이전과 이후의 차이, 그 작동으로 인해 배제되는 범주와 포함되는 범주 간 차이, 그러한 배제/포함의 대상과 배제/포함의 실행자로서의 객체와 주체 간 차이가 생겨난다는 점에 근거하는 보편성을 분석에서 일관되게 적용한다. 이 보편성으로 인해, 우리는 시간적 차원, 사실적 차원, 사회적 차원의 공동생산 원리를 의미체계인 심리적 체계와 사회적 체계에도 적용할 수 있다. 이러한 패러다임적 전환을 통해, 루만의 사회학은 독립적인 사회적 체계라는 발견적 이념을 통해 사회적인 것(the Social)을 연구한다. 사회적 체계는 다시금 상호작용체계, 조직체계, 사회(societal)체계의 하위 유형으로 세분되며, 이 세 가지 체계들의 발전과 상호 연동은 사회의 변천 과정을 분절적 분화, 계층적 분화, 기능적 분화의 우선권 경합에 따라 분석할 가능성을 열어준다. 이상의 분석에 기초하면, 기능적으로 분화된 세계사회 테제는 근대사회가 기능적 분화만으로 작동한다는 것을 뜻하지 않고, 전근대적인 계층적 분화에 대해 근대적인 기능적 분화가 우선권을 획득했음을 진술한다.