Nano-oxide dispersion–strengthened (ODS) superalloys have attracted attention because of their outstanding mechanical reinforcement mechanism. Dispersed oxides increase the material’s strength by preventing grain growth and recrystallization, as well as increasing creep resistance. In this research, atomic layer deposition (ALD) was applied to synthesize an ODS alloy. It is useful to coat conformal thin films even on complex matrix shapes, such as nanorods or powders. We coated an Nb-Si–based superalloy with TiO2 thin film by using rotary-reactor type thermal ALD. TiO2 was grown by controlling the deposition recipe, reactor temperature, N2 flow rate, and rotor speed. We could confirm the formation of uniform TiO2 film on the surface of the superalloy. This process was successfully applied to the synthesis of an ODS alloy, which could be a new field of ALD applications.

As the limitations of Moore’s Law become evident, there has been growing interest in advanced packaging technologies. Among various 3D packaging techniques, Cu-SiO2 hybrid bonding has gained attention in heterogeneous devices. However, certain issues, such as its high-temperature processing conditions and copper oxidation, can affect electrical properties and mechanical reliability. Therefore, we studied depositing only a heterometal on top of the Cu in Cu-SiO2 composite substrates to prevent copper surface oxidation and to lower bonding process temperature. The heterometal needs to be deposited as an ultra-thin layer of less than 10 nm, for copper diffusion. We established the process conditions for depositing a Co film using a Co(EtCp)2 precursor and utilizing plasma-enhanced atomic layer deposition (PEALD), which allows for precise atomic level thickness control. In addition, we attempted to use a growth inhibitor by growing a self-assembled monolayer (SAM) material, octadecyltrichlorosilane (ODTS), on a SiO2 substrate to selectively suppress the growth of Co film. We compared the growth behavior of the Co film under various PEALD process conditions and examined their selectivity based on the ODTS growth time.

Recently, the electron transport layer (ETL) has become one of the key components for high-performance perovskite solar cell (PSC). This study is motivated by the nonreproducible performance of ETL made of spin coated SnO2 applied to a PSC. We made a comparative study between tin oxide deposited by atomic layer deposition (ALD) or spin coating to be used as an ETL in N-I-P PSC. 15 nm-thick Tin oxide thin films were deposited by ALD using tetrakisdimethylanmiotin (TDMASn) and using reactant ozone at 120 °C. PSC using ALD SnO2 as ETL showed a maximum efficiency of 18.97 %, and PSC using spin coated SnO2 showed a maximum efficiency of 18.46 %. This is because the short circuit current (Jsc) of PSC using the ALD SnO2 layer was 0.75 mA/cm2 higher than that of the spin coated SnO2. This result can be attributed to the fact that the electron transfer distance from the perovskite is constant due to the thickness uniformity of ALD SnO2. Therefore ALD SnO2 is a candidate as a ETL for use in PSC vacuum deposition.

Atomic layer etching (ALE) is a promising technique with atomic-level thickness controllability and high selectivity based on self-limiting surface reactions. ALE is performed by sequential exposure of the film surface to reactants, which results in surface modification and release of volatile species. Among the various ALE methods, thermal ALE involves a thermally activated reaction by employing gas species to release the modified surface without using energetic species, such as accelerated ions and neutral beams. In this study, the basic principle and surface reaction mechanisms of thermal ALE?processes, including “fluorination-ligand exchange reaction”, “conversion-etch reaction”, “conversion-fluorination reaction”, “oxidation-fluorination reaction”, “oxidation-ligand exchange reaction”, and “oxidation-conversion-fluorination reaction” are described. In addition, the reported thermal ALE processes for the removal of various oxides, metals, and nitrides are presented.

PURPOSES : Preventive pavement maintenance is an economical and efficient method of infrastructure management. This study aims to improve the performance of cold thin-layer asphalt pavement, which is mainly used in earthwork pavement, and for bridge overlays and structures. METHODS : A cold asphalt mixture of modified emulsified asphalt and RAP was prepared for cold recycled thin-layer asphalt pavement. The performance of the mixture as a function of fiber reinforcement to improve flexural strength and crack resistance was evaluated. RESULTS : The use of RAP aggregate in cold asphalt mixture was found to increase the cohesive strength of the mixture and improve the wet abrasion resistance due to the effect of the residual binder. As a result of the loaded wheel test and flexural tension test with the addition of fiber reinforcement, it was found that the crack resistance of 0.4 % glass fiber was the best, and especially, the flexibility at low temperature was excellent. CONCLUSIONS : The cold recycled thin-layer asphalt pavement mixture has improved cohesive strength, flexural strength, and crack resistance compared to existing cold asphalt pavement materials, so it will contribute to economical and effective maintenance in preventive maintenance of bridge overlays and structural pavements.

In the recent years, thin film solar cells (TFSCs) have emerged as a viable replacement for crystalline silicon solar cells and offer a variety of choices, particularly in terms of synthesis processes and substrates (rigid or flexible, metal or insulator). Among the thin-film absorber materials, SnS has great potential for the manufacturing of low-cost TFSCs due to its suitable optical and electrical properties, non-toxic nature, and earth abundancy. However, the efficiency of SnS-based solar cells is found to be in the range of 1 ~ 4 % and remains far below those of CdTe-, CIGS-, and CZTSSe-based TFSCs. Aside from the improvement in the physical properties of absorber layer, enormous efforts have been focused on the development of suitable buffer layer for SnS-based solar cells. Herein, we investigate the device performance of SnS-based TFSCs by introducing double buffer layers, in which CdS is applied as first buffer layer and ZnMgO films is employed as second buffer layer. The effect of the composition ratio (Mg/(Mg+Zn)) of RF sputtered ZnMgO films on the device performance is studied. The structural and optical properties of ZnMgO films with various Mg/(Mg+Zn) ratios are also analyzed systemically. The fabricated SnS-based TFSCs with device structure of SLG/Mo/SnS/CdS/ZnMgO/AZO/Al exhibit a highest cell efficiency of 1.84 % along with open-circuit voltage of 0.302 V, short-circuit current density of 13.55 mA cm−2, and fill factor of 0.45 with an optimum Mg/(Mg + Zn) ratio of 0.02.

리튬금속전지(LMB)는 매우 큰 이론 용량을 갖지만 단락(short circuit), 수명 감소 등을 야기하는 덴드라이트(dendrite) 가 형성되는 큰 문제점을 갖고 있다. 본 연구에서는 poly(dimethylsiloxane) (PDMS)에 graphene oxide (GO) nanosheet를 고르게 분산시킨 PDMS/GO 복합체를 합성하였고 이를 박막 형태로 코팅하여 덴드라이트의 형성을 물리적으로 억제할 수 있는 막의 효과를 이끌어내었다. PDMS의 경우, 그 자체로는 이온 전도체가 아니기 때문에 리튬 이온의 통로를 형성시켜 리튬 이온의 이동을 원활하게 하기 위하여 5wt% 불산(HF)으로 에칭하여 PDMS/GO 박막이 이온전도성을 가질 수 있도록 하였다. 주사전자현미경(scanning electron microscopy, SEM)을 통해 전면 및 단면을 관찰하여 PDMS/GO 박막의 형상을 확인하였다. 그리고 PDMS/GO 박막을 리튬금속전지에 적용하여 실시한 배터리 테스트 결과, 100번째 사이클까지 쿨롱 효율(columbic efficiency) 이 평균 87.4%로 유지되었고, 박막이 코팅되지 않은 구리 전극보다 과전압이 감소되었음을 전압 구배(voltage profile) 를 통해 확인하였다.

Aluminum nitride (AlN) has versatile and intriguing properties, such as wide direct bandgap, high thermal conductivity, good thermal and chemical stability, and various functionalities. Due to these properties, AlN thin films have been applied in various fields. However, AlN thin films are usually deposited by high temperature processes like chemical vapor deposition. To further enlarge the application of AlN films, atomic layer deposition (ALD) has been studied as a method of AlN thin film deposition at low temperature. In this mini review paper, we summarize the results of recent studies on AlN film grown by thermal and plasma enhanced ALD in terms of processing temperature, precursor type, reactant gas, and plasma source. Thermal ALD can grow AlN thin films at a wafer temperature of 150~550 oC with alkyl/amine or chloride precursors. Due to the low reactivity with NH3 reactant gas, relatively high growth temperature and narrow window are reported. On the other hand, PEALD has an advantage of low temperature process, while crystallinity and defect level in the film are dependent on the plasma source. Lastly, we also introduce examples of application of ALD-grown AlN films in electronics.

In recent years, there have been applied methods for minimizing noise by adjusting the method of installing soundproof walls, soundproof tunnels, soundproofing rims, environmental facilities, etc., and the shape of the surface texture of tire treads and packaging materials for the purpose of reducing road noise. Low noise pavement methods such as rubber asphalt (CRM), open graded asphalt concrete (OGAC), permeable Friction Courses (PFC), open graded friction courses (OGFC) and porous asphalt have been applied to reduce road noise. Especially, porous pavement is the most widely used low noise pavement with porous structure, which can reduce noise and drain water through continuous void of pavement. On the other hand, porous asphalt pavement has problems such as reduction of noise reduction effect and difficulty of road surface management due to void closing and increase of construction cost. The purpose of this study is to develop ultra-thin layer hot mix asphalt pavement method which maximizes road noise reduction effect by surface micro voids (Recover asphalt pavement) to improve void clogging of present porous pavement method. For this study, maximum size 5mm aggregate and cationic-treated fiber reinforced asphalt modifier (CSM) were used. The Marshall design method was applied grain-size distribution curve was based on SMA mix design. Marshall test, TSR, MMLS3 test and Hamburg test were carried out to evaluate the mechanical properties of ultra -thin layered asphalt pavement method with surface micro voids. Also, the effect of road noise reduction was evaluated through field application in urban area.

We investigated the effect of ZnO buffer layer on the formation of ZnO thin film by ultrasonic assisted spray pyrolysis deposition. ZnO buffer layer was formed by wet solution method, which was repeated several times. Structural and optical properties of the ZnO thin films deposited on the ZnO buffer layers with various cycles and at various temperatures were investigated by field-emission scanning electron microscopy, X-ray diffraction, and photoluminescence spectrum analysis. The structural investigations showed that three-dimensional island shaped ZnO was formed on the bare Si substrate without buffer layers, while two-dimensional ZnO thin film was deposited on the ZnO buffer layers. In addition, structural and optical investigations showed that the crystalline quality of ZnO thin film was improved by introducing the buffer layers. This improvement was attributed to the modulation of the surface energy of the Si surface by the ZnO buffer layer, which finally resulted in a modification of the growth mode from three to two-dimensional.

FO is prominent membrane technology for desalination due to no hydraulic pressure requirement and low fouling propensity compared to RO. TFC membrane was widely used due to excellent perm-selectivity and chemical resistance. TFC membrane consists of dense and support layer. Academic efforts focused on advance TFC membranes characteristics and performances. This work attempts to fabricate TFC FO membrane with highly permeable ultra-thin intermediate layer on the support layer using polydopamine and graphene oxide. Role of the intermediate layer on performances was demonstrated via characterization and FO operation.

We report on a unique fabrication technique, DSC for high performance PA TFC RO membranes. DSC allows the simultaneous and continuous spreading of two reactive monomer solutions to create an unsupported PA layer, which is then adhered onto a porous support to form a membrane. DSC facilitates the characterization of the PA layer structure by easily isolating it. The DSC-PA layer exhibits a thinner and smoother structure with a more wettable and less negatively charged surface than one prepared via conventional interfacial polymerization (IP). DSC enables the formation of an extremely thin (~9 nm) and dense PA layer using a very low MPD concentration, which is not feasible by conventional IP. Importantly, the DSC-assembled membrane shows the excellent water flux and NaCl rejection, exceeding both the IP control and commercial RO membranes.

We have demonstrated the production of thin films containing multilayer graphene-coated copper nanoparticles (MGCNs) by a commercial electrodeposition method. The MGCNs were produced by electrical wire explosion, an easily applied technique for creating hybrid metal nanoparticles. The nanoparticles had average diameters of 10–120 nm and quasi-spherical morphologies. We made a complex-electrodeposited copper thin film (CETF) with a thickness of 4.8 μm by adding 300 ppm MGCNs to the electrolyte solution and performing electrodeposition. We measured the electric properties and performed corrosion testing of the CETF. Raman spectroscopy was used to measure the bonding characteristics and estimate the number of layers in the graphene films. The resistivity of the bare-electrodeposited copper thin film (BETF) was 2.092 × 10–6 Ω·cm, and the resistivity of the CETF after the addition of 300 ppm MGCNs was decreased by 2% to ~2.049 × 10–6 Ω·cm. The corrosion resistance of the BETF was 9.306 Ω, while that of the CETF was increased to 20.04 Ω. Therefore, the CETF with MGCNs can be used in interconnection circuits for printed circuit boards or semiconductor devices on the basis of its low resistivity and high corrosion resistance.