• 한국결정성장학회지
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• 제30권6호
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• pp.220-225
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• 2020

반응부, 이송부, 포집부로 이루어진 기상합성장치를 구축하여 Oxide TFT의 대표적인 물질인 IGZO 반도체용 타겟의 기초 소재인 산화갈륨 나노분말을 기상합성법으로 제조하였다. 반응부에서 갈륨 금속을 증발시켜 1150℃ 이상의 온도에서 산화갈륨 나노분말이 만들어지는 것을 확인하였다. 갈륨 금속은 증발 즉시 반응부에서 산화갈륨 나노분말로 합성되었으며, 반응부의 온도가 증가함에 따라 높은 결정도와 큰 입자 크기를 보였다. 또한, 합성된 산화갈륨 나노분말은 구형의 모양을 가지면서 매우 낮은 응집성을 가졌다. 기상합성법으로 얻은 산화갈륨 나노분말을 상용 산화인듐, 산화아연 분말(몰비 = 1 : 1 : 1)과 혼합하여 소결을 시행한 결과, 소결온도 1450℃에서 5.83 g/㎤의 최대밀도를 얻어 같은 조건하에서 상용 산화갈륨 분말을 이용해 만든 IGZO 소결체(5.61 g/㎤)보다 높은 밀도를 얻음을 볼 수 있었다.

• 한국진공학회지
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• 제18권1호
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• pp.73-78
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• 2009

본 연구에서는 metal oxide chemical vapor deposition (MOCVD)을 이용하여 p형 실리콘(100) 기판 위에 30 nm 두께의 산화 아연 완충층을 $500^{\circ}C$ 에서 증착 시킨 후, 그 위에 산화 아연 나노로드를 수열합성법을 이용하여 성장시켰다. 그리고 산화아연 나노로드 성장 시 0.02몰${\sim}$0.5몰의 다양한 농도의 전구체를 사용함으로써 그에 따라 변화되는 산화 아연 나노로드의 배열상태, 구조적, 그리고 광학적 특성 평가를 실시하였다. 특성 평가는 FE-SEM(field emission scanning electron microscopy), XRD(X-ray diffraction), 그리고 PL(photoluminescence) 등의 분석 방법들을 통해 이루어졌다 본 연구를 통하여 전구체의 농도가 증가할수록 나노로드의 직경과 길이가 길어지며 0.3몰의 농도에서 뛰어난 광학 특성이 나타나는 것을 발견할 수 있었다.

• 한국진공학회:학술대회논문집
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• 한국진공학회 2013년도 제44회 동계 정기학술대회 초록집
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• pp.79-79
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• 2013

Quantum-structures with nanoparticles have been attractive for various electronic and photonic devices [1,2]. In recent, nonvolatile memories such as nano-floating gate memory (NFGM) and resistance random access memory (ReRAM) have been studied using silicides, metals, and metal oxides nanoparticles [3,4]. In this study, we fabricated nonvolatile memories with silicides (WSi2, Ti2Si, V2Si) and metal-oxide (Cu2O, Fe2O3, ZnO, SnO2, In2O3 and etc.) nanoparticles embedded in polyimide matrix, and photovoltaic device also with SiC nanoparticles. The capacitance-voltageand current-voltage data showed a threshold voltage shift as a function of write/erase voltage, which implies the carrier charging and discharging into the metal-oxide nanoparticles. We have investigated also the electrical properties of ReRAM consisted with the nanoparticles embedded in ZnO, SiO2, polyimide layer on the monolayered graphene. We will discuss what the current bistability of the nanoparticle ReRAM with monolayered graphene, which occurred as a result of fully functional operation of the nonvolatile memory device. A photovoltaic device structure with nanoparticles was fabricated and its optical properties were also studied by photoluminescence and UV-Vis absorption measurements. We will discuss a feasibility of nanoparticles to application of nonvolatile memories and photovoltaic devices.

• 한국분말재료학회지
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• 제9권1호
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• pp.25-31
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• 2002

The efects of mechanical aloying conditions and the type of reducing agent on the solid state reductionof haematite $Fe_2O_3$ have been investigated at room temperature. Aluminium titanium zinc and copper were used as reducing agent. Nanocomposites of metal-oxide in which oxide particles with nano size were dispersed in Fe matrix were obtained by mechanical alloying of $Fe_2O_3$ with aluminium and titanium respectively However the reduction of $Fe_2O_3$ by coppe was not occurred Composite materials of iron with $Al_2O_3$ and $TiO_2$ were obtained from the system of $Fe_2O_3-Al$ and $Fe_2O_3-Ti$ after ball milling for 20 hrs and 30 hrs respectively. And the system of $Fe_2O_3-Zn$ resulted in the formationof FeO with ZnO after ball milling of 120 hrs. The final grain sizes of iron estimated by X-ray diffraction line-width measurement were in the ranges of 24~33 nm.

• 자원리싸이클링
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• 제30권1호
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• pp.66-76
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• 2021

전기로 제강분진 중에는 아연(Zn), 납(Pb)등과 같은 유가금속들이, 다양한 화합물(산화물 또는 염화물 등)의 형태로 다량 함유되어 있다. 전기로 제강분진 내에 함유되어 있는 이들 유용금속원소들을, 가장 효율적이며 안정적으로 회수할 수 있는 대표적인 방법으로서는 Rotary Kiln Process가 있다. Rotary Kiln Process는 전기로 제강분진에 환원제(Coke, 무연탄)와 석회석(염기도 제어용)을 첨가하여 성형한 후에 가열함으로서, 아연성분을 조산화아연(Crude Zinc Oxide : 60% Zn)의 형태로 회수하는 방법으로 오래전에 이미 상용화되었으며, 지금도 공정 및 설비의 단점을 개선하기 위한 연구개발을 지속적으로 수행하고 있다. 현재 국내에서도 전기로 제강분진을 재활용하여 조산화아연을 생산하는 다수의 상용화공장들이 가동되고 있다. 조산화아연 중에는, 아연성분 외에도 다양한 기타의 성분원소들(Pb, Cd, Sn, In, Fe, Cl, F 등)이 산화물, 염화물, 알칼리 화합물 등의 형태로 함께 혼재되어 있다. 그러므로 조산화아연을 건식 또는 습식아연제련용 원료로서 그대로 사용하게 되면 조산화아연에 함유된 이들 불순물 성분들이 미치는 악영향으로 인하여, 아연제련과정에서 많은 문제점들이 발생하므로. 따라서 이들 불순물 성분원소들을 가능하면 모두 제거하기 위한 건식 또는 습식정제공정이 추가로 필요하다. 따라서 본 연구에서는 조산화아연의 건식휘발 정제공정에서 발생되어 백필터에 포집된 아연(Zn) 및 납(Pb)을 함유한 2차분진(2nd Dust)으로부터 아연(Zn)과 납(Pb)을 효율적으로 분리하고, 더욱 부가가치를 높이기 위하여 Zn-cementation법으로 이들 성분원소들을 금속탄산염의 형태로 분리회수할 수 있는 공정기술에 대하여 기초적인 연구를 수행하였다.

• Bulletin of the Korean Chemical Society
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• 제30권8호
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• pp.1738-1742
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• 2009

Nanocrystalline Zn$Fe_2O_4$ oxide-semiconductor with spinel structure was synthesized by the polymerized complex (PC) method and investigated for its photocatalytic and photoelectric properties. The observation of a highly pure phase and a lower crystallization temperature in Zn$Fe_2O_4$ made by PC method is in total contrast to that was observed in Zn$Fe_2O_4$ prepared by the conventional solid-state reaction (SSR) method. The band gap of the nanocrystalline Zn$Fe_2O_4$ determined by UV-DRS was 1.90 eV (653 nm). The photocatalytic activity of Zn$Fe_2O_4$ prepared by PC method as investigated by the photo-decomposition of isopropyl alcohol (IPA) under visible light (${\geq}$ 420 nm) was much higher than that of the Zn$Fe_2O_4$ prepared by SSR as well as Ti$O_{2-x}N_x$. High photocatalytic activity of Zn$Fe_2O_4$ prepared by PC method was mainly due to its surface area, crystallinity and the dispersity of platinum metal over Zn$Fe_2O_4$.

• 센서학회지
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• 제28권3호
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• pp.139-145
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• 2019

Precautionary detection of chemical warfare agents (CWAs) has been an important global issue mainly owing to their toxicity. To achieve proper detection, many studies have been conducted to develop sensitive gas sensors for CWAs. In particular, metal-oxide semi-conductors (MOS) have been investigated as promising sensing materials owing to their abundance in nature and excellent sensitivity. In this review, we mainly focus on various MOS-based gas sensors that have been fabricated for the detection of two specific CWA simulants, 2-chloroethyl ethyl sulfide (2-CEES) and dimethyl methyl phosphonate (DMMP), which are simulants of sulfur mustard and sarin, respectively. In the case of 2-CEES, we mainly discuss $CdSnO_3-$ and ZnO-based sensors and their reaction mechanisms. In addition, a method to improve the selectivity of ZnO-based sensors is mentioned. Various sensors and their sensing mechanisms have been introduced for the detection of DMMP. As the reaction with DMMP may directly affect the sensing properties of MOS, this paper includes previous studies on its poisoning effect. Finally, promising sensing materials for both gases are proposed.

• Nuclear Engineering and Technology
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• 제50권3호
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• pp.416-424
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• 2018

Microstructure of oxide formed on Zr-Nb-Sn tube sample was intensively examined by scanning transmission electron microscopy after exposure to simulated primary water chemistry conditions of various concentrations of Zn (0 or 30 ppb) and dissolved hydrogen ($H_2$) (30 or 50 cc/kg) for various durations without applying desirable heat flux. Microstructural analysis indicated that there was no noticeable change in the microstructure of the oxide corresponding to water chemistry changes within the test duration of 100 days (pretransition stage) and no significant difference in the overall thickness of the oxide layer. Equiaxed grains with nano-size pores along the grain boundaries and microcracks were dominant near the water/oxide interface, regardless of water chemistry conditions. As the metal/oxide interface was approached, the number of pores tended to decrease. However, there was no significant effect of $H_2$ concentration between 30 cc/kg and 50 cc/kg on the corrosion of the oxide after free immersion in water at $360^{\circ}C$. The adsorption of Zn on the cladding surface was observed by X-ray photoelectron spectroscopy and detected as ZnO on the outer oxide surface. From the perspective of $OH^-$ ion diffusion and porosity formation, the absence of noticeable effects was discussed further.

• 한국진공학회:학술대회논문집
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• 한국진공학회 2016년도 제50회 동계 정기학술대회 초록집
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• pp.287.1-287.1
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• 2016

Three-dimensional (3-D) semiconductor nanoarchitectures, including nano- and micro- rods, pyramids, and disks, are emerging as one of the most promising elements for future optoelectronic devices. Since these 3-D semiconductor nanoarchitectures have many interesting unconventional properties, including the use of large light-emitting surface area and semipolar/nonpolar nano- or micro-facets, numerous studies reported on novel device applications of these 3-D nanoarchitectures. In particular, 3-D nanoarchitecture devices can have noticeably different current spreading characteristics compared with conventional thin film devices, due to their elaborate 3-D geometry. Utilizing this feature in a highly controlled manner, color-tunable light-emitting diodes (LEDs) were demonstrated by controlling the spatial distribution of current density over the multifaceted GaN LEDs. Meanwhile, for the fabrication of high brightness, single color emitting LEDs or laser diodes, uniform and high density of electrical current must be injected into the entire active layers of the nanoarchitecture devices. Here, we report on a new device structure to inject uniform and high density of electrical current through the 3-D semiconductor nanoarchitecture LEDs using metal core inside microtube LEDs. In this work, we report the fabrications and characteristics of metal-cored coaxial $GaN/In_xGa_{1-x}N$ microtube LEDs. For the fabrication of metal-cored microtube LEDs, $GaN/In_xGa_{1-x}N/ZnO$ coaxial microtube LED arrays grown on an n-GaN/c-Al2O3 substrate were lifted-off from the substrate by wet chemical etching of sacrificial ZnO microtubes and $SiO_2$ layer. The chemically lifted-off layer of LEDs were then stamped upside down on another supporting substrates. Subsequently, Ti/Au and indium tin oxide were deposited on the inner shells of microtubes, forming n-type electrodes of the metal-cored LEDs. The device characteristics were investigated measuring electroluminescence and current-voltage characteristic curves and analyzed by computational modeling of current spreading characteristics.

• 한국진공학회:학술대회논문집
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• 한국진공학회 2016년도 제50회 동계 정기학술대회 초록집
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• pp.268-268
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• 2016

Chemical sensors have attracted much attention due to their various applications such as agriculture product, cosmetic and pharmaceutical components and clinical control. A conventional chemical and biological sensor is consists of fluorescent dye, optical light sources, and photodetector to quantify the extent of concentration. Such complicated system leads to rising cost and slow response time. Until now, the most contemporary thin film transistors (TFTs) are used in the field of flat panel display technology for switching device. Some papers have reported that an interesting alternative to flat panel display technology is chemical sensor technology. Recent advances in chemical detection study for using TFTs, benefits from overwhelming progress made in organic thin film transistors (OTFTs) electronic, have been studied alternative to current optical detection system. However numerous problems still remain especially the long-term stability and lack of reliability. On the other hand, the utilization of metal oxide transistor technology in chemical sensors is substantially promising owing to many advantages such as outstanding electrical performance, flexible device, and transparency. The top-gate structure transistor indicated long-term atmosphere stability and reliability because insulator layer is deposited on the top of semiconductor layer, as an effective mechanical and chemical protection. We report on the fabrication of InGaZnO TFTs with silver nanowire as the top gate electrode for the aim of chemical materials detection by monitoring change of electrical properties. We demonstrated that the improved sensitivity characteristics are related to the employment of a unique combination of nano materials. The silver nanowire top-gate InGaZnO TFTs used in this study features the following advantages: i) high sensitivity, ii) long-term stability in atmosphere and buffer solution iii) no necessary additional electrode and iv) simple fabrication process by spray.