• Journal of Electrochemical Science and Technology
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• 제10권2호
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• pp.123-130
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• 2019

We investigated the electrochemical behavior of an electrode coated with a nickel hexacyanoferrate/graphene oxide (NiPB/GO) composite to evaluate its potential use for the electrochemical separation of radioactive Cs as a promising approach for reducing secondary Cs waste after decontamination. The NiPB/GO-modified electrode showed electrochemically switched ion exchange capability with excellent selectivity for Cs over other alkali metals. Furthermore, the repetitive ion insertion and desertion test for assessing the electrode stability showed that the electrochemical ion exchange capacity of the NiPB/GO-modified electrode increased further with potential cycling in 1 M of $NaNO_3$. In particular, this electrochemical treatment enhanced Cs uptake by nearly two times compared to that of NiPB/GO and still retained the ion selectivity of NiPB, suggesting that the electrochemically treated NiPB/GO composite shows promise for nuclear wastewater treatment.

• 방사선산업학회지
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• 제18권2호
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• pp.127-132
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• 2024

Large amounts of liquid radioactive waste or radioactive contaminated water could be produced during the treatment of radiation accidents or during the dismantling and decontamination process of nuclear power plants. Since most of the decontamination agents to date are difficult to recover after adsorption of radioactive isotopes, their use in open environments such as rivers, reservoirs, or oceans is limited. In this study, as a radioactive decontamination agent that can overcome the current limitations when used in an open environment, a paramagnetic core inorganic composite (PMCIC) decomposite agent with high selectivity to cesium ions was developed. PMCore was prepared by synthesizing paramagnetic iron oxide nanoparticles, and inorganic crystals such as metal-ferrocyanide were conjugated to the surface so that PMCore could be selective to cesium ions. The developed PMCIC could be easily recovered from the water by magnetism and could adsorb up to 94 μM of Cs atoms per 1 g of PMCIC.

• 한국재료학회:학술대회논문집
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• 한국재료학회 2006년도 추계학술발표대회 및 제11회 신소재 심포지엄
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• pp.15.1-15.1
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• 2006

• Transactions on Electrical and Electronic Materials
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• 제14권4호
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• pp.216-220
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• 2013

The etching characteristics of indium zinc oxide (IZO) in $Cl_2/Ar$ plasma were investigated, including the etch rate and selectivity of IZO. The IZO etch rate showed non-monotonic behavior with increasing $Cl_2$ fraction in the $Cl_2/Ar$ plasma, and with increasing source power, bias power, and process pressure. In the $Cl_2/Ar$ (75:25%) gas mixture, a maximum IZO etch rate of 87.6 nm/min and etch selectivity of 1.09 for IZO to $SiO_2$ were obtained. Owing to the relatively low volatility of the by-products formation, ion bombardment was required, in addition to physical sputtering, to obtain high IZO etch rates. The chemical state of the etched surfaces was investigated with X-ray photoelectron spectroscopy. These data suggested that the IZO etch mechanism was ion-enhanced chemical etching.

• Journal of Industrial and Engineering Chemistry
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• 제67권
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• pp.156-163
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• 2018

High-performance mixed-matrix membranes that comprise both zeolitic imidazolate framework-8 (ZIF-8) and graphene oxide (GO) were synthesized with a solution casting technique to realize excellent $CO_2/CH_4$ separation. The incorporation of ZIF-8 nanocrystals alone in ODPA-TMPDA polyimide can be used to significantly enhance $CO_2$ permeability compared with that of pure ODPA-TMPDA. Meanwhile, the addition of a GO nanostack alone in ODPA-TMPDA contributes to improved $CO_2/CH_4$ selectivity. Hence, a composite membrane that contains both fillers displays significant enhancements in $CO_2$ permeability (up to 60%) and $CO_2/CH_4$ selectivity (up to 28%) compared with those of pure polymeric membrane. Furthermore, in contrast to the ZIF-8 mixed-matrix membrane, which showed decreased mechanical stability, it was found that the incorporation of GO could improve the mechanical strength of mixed-matrix membranes. Overall, the synergistic effects of the use of both fillers together are successfully demonstrated in this paper. Such significant improvements in the mixed-matrix membrane's $CO_2/CH_4$ separation performance and mechanical strength suggest a feasible and effective approach for potential biogas upgrading and natural gas purification.

• 센서학회지
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• 제29권6호
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• pp.407-411
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• 2020

In this study, we propose an array-type gas sensor with high selectivity and response using multiple oxide semiconductors. The sensor array was composed of SnO₂ and In₂O₃, and the detection characteristics were improved by using Pt, Au, and Pd catalysts. All samples were deposited directly on the Pt interdigitated electrode (IDE) through the e-beam evaporator glancing angle deposition (GAD) method. They grew in the form of well-aligned nanorods at off-axis angles. The prepared SnO₂ and In₂O₃ nanorod samples were exposed to CH₃COCH₃, C₇H₈, and NO₂ gases in a 300℃ dry condition. Au-decorated SnO₂, Au-decorated In₂O₃, and Pd-decorated In₂O₃ exhibited high selectivity for CH₃COCH₃, C₇H₈, and NO₂, respectively. They demonstrated a high detection limit of the sub ppb level computationally. In addition, measurements from each sensor were executed in the 40% relative humidity condition. Although there was a slight reduction in detection response, high selectivity and distinguishable detection characteristics were confirmed.

• Nano
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• 제13권11호
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• pp.1850131.1-1850131.19
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• 2018

In this paper, an electrochemical sensor for epinephrine (EP), a neurotransmitter was developed by anchoring molecularly imprinted polymeric matrix (MIP) on the surface of gold-coated quartz crystal electrode of electrochemical quartz crystal microbalance (EQCM) using starch nanoparticles (Starch NP) - reduced graphene oxide (RGO) nanocomposite as polymeric format for the first time. Use of EP in therapeutic treatment requires proper dose and route of administration. Proper follow-up of neurological disorders and timely diagnosis of them has been found to depend on EP level. The MIP sensor was developed by electrodeposition of starch NP-RGO composite on EQCM electrode in presence of template EP. As the imprinted sites are located on the surface, high specific surface area enables good accessibility and high binding affinity to template molecule. Differential pulse voltammetry (DPV) and piezoelectrogravimmetry were used for monitoring binding/release, rebinding of template to imprinted cavities. MIP-coated EQCM electrode were characterized by contact angle measurements, AFM images, piezoelectric responses including viscoelasticity of imprinted films, and other voltammetric measurements including direct (DPV) and indirect (using a redox probe) measurements. Selectivity was assessed by imprinting factor (IF) as high as 3.26 (DPV) and 3.88 (EQCM). Sensor was rigorously checked for selectivity in presence of other structurally close analogues, real matrix (blood plasma), reproducibility, repeatability, etc. Under optimized conditions, the EQCM-MIP sensor showed linear dynamic ranges ($1-10{\mu}M$). The limit of detection 40 ppb (DPV) and 290 ppb (EQCM) was achieved without any cross reactivity and matrix effect indicating high sensitivity and selectivity for EP. Hence, an eco-friendly MIP-sensor with high sensitivity and good selectivity was fabricated which could be applied in "real" matrices in a facile manner.

• 한국진공학회지
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• 제15권6호
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• pp.630-636
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• 2006

플래시 메모리 반도체의 고집적화와 고밀도화가 진행함에 따라 플래시 메모리의 트랜지스터 안 선폭을 중심으로 게이트 패턴의 미세화가 진행 중이다. 최근 100 nm 이하의 선폭을 구현하기 위해서 ONO(oxide-nitride-oxide)를 사용하기 위한 연구가 개발 중이고, 이러한 100 nm이하의 미세 선폭으로 갈수록 식각 속도와 식각의 프로파일은 중요한 요인으로 작용하고 있다. ICP 식각 장비를 이용하여, power를 50 W 증가 하였을 때, 각각 식각 속도와 포토레지스트와의 선택비를 확인 한 결과 platen power를 100 W로 올렸을 경우 가장 좋은 결과를 나타내었다. 100 W에서 HBr가스의 유량에 변화를 주었을 경우 가스의 양을 증가 할수록 식각 속도는 감소하였지만, 포토레지스트와의 선택비는 증가함을 보였다. 유도결합 플라즈마 식각 장비를 가지고 platen power를 100 W, HBr gas를 35 sccm 공급하여 하부 층에 노치가 형성이 안되고, 식각 속도 320 nm/min, 감광액과의 선택비 3.5:1, 측면식각 프로파일이 수직인 공정 조건을 찾았다.

• 한국전기전자재료학회논문지
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• 제15권10호
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• pp.838-843
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• 2002

Chemical mechanical polishing(CMP) process has been widely used to planarize dielectric layers, which can be applied to the integrated circuits for deep sub-micron technology. The reverse moat etch process has been used for the shallow trench isolation(STI)-chemical mechanical polishing(CMP) process with conventional low selectivity slurries. Thus, the process became more complex, and the defects were seriously increased. In this paper, we studied the direct STI-CMP process without reverse moat etch step using high selectivity slurry(HSS). As our experimental results show, it was possible to achieve a global planarization without the complicated reverse moat process, the STI-CMP process could be dramatically simplified, and the defect level was reduced. Therefore the throughput, yield, and stability in the ULSI semiconductor device fabrication could be greatly improved.

• 한국진공학회:학술대회논문집
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• 한국진공학회 2010년도 제39회 하계학술대회 초록집
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• pp.124-124
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• 2010

Currently, extreme ultraviolet lithography (EUVL) is being investigated for next generation lithography. EUVL is one of competitive lithographic technologies for sub-22nm fabrication of nano-scale Si devices that can possibly replace the conventional photolithography used to make today's microcircuits. Among the core EUVL technologies, mask fabrication is of considerable importance due to the use of new reflective optics having a completely different configuration compared to those of conventional photolithography. Therefore, new materials and new mask fabrication process are required for high performance EUVL mask fabrication. This study investigated the etching properties of SnO2 (Tin Oxide) as a new absorber material for EUVL binary mask. The EUVL mask structure used for etching is SnO2 (absorber layer) / Ru (capping / etch stop layer) / Mo-Si multilayer (reflective layer) / Si (substrate). Since the Ru etch stop layer should not be etched, infinitely high selectivity of SnO2 layer to Ru ESL is required. To obtain infinitely high etch selectivity and very low LER (line edge roughness) values, etch parameters of gas flow ratio, top electrode power, dc self - bias voltage (Vdc), and etch time were varied in inductively coupled Cl2/Ar plasmas. For certain process window, infinitely high etch selectivity of SnO2 to Ru ESL could be obtained by optimizing the process parameters. Etch characteristics were measured by on scanning electron microscopy (SEM) and X-ray photoelectron spectroscopy (XPS) analyses. Detailed mechanisms for ultra-high etch selectivity will be discussed.