38 results on '"Taeyong Eom"'
Search Results
2. Atomic Layer Deposition of Ru Thin Film Using a Newly Synthesized Precursor with Open‐Coordinated Ligands
- Author
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Seung Hoon Oh, Jeong Min Hwang, Hyeonbin Park, Dongseong Park, Young Eun Song, Eun Chong Ko, Tae Joo Park, Taeyong Eom, and Taek‐Mo Chung
- Subjects
Mechanics of Materials ,Mechanical Engineering - Published
- 2023
3. Cross-linked structure of self-aligned p-type SnS nanoplates for highly sensitive NO2 detection at room temperature
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Young Geun Song, In-Hwan Baek, Jae-Gyun Yim, Taeyong Eom, Taek-Mo Chung, Chul-Ho Lee, Cheol Seong Hwang, Chong-Yun Kang, and Seong Keun Kim
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Renewable Energy, Sustainability and the Environment ,General Materials Science ,General Chemistry - Abstract
A highly sensitive NO2 gas sensor of p-type SnS operating at room temperature is developed using crosslinked SnS nanoplates self-formed only on SiO2 nanorods, without an additional patterning process.
- Published
- 2022
4. Novel Heteroleptic Tin(II) Complexes Capable of Forming SnO and SnO2 Thin Films Depending on Conditions Using Chemical Solution Deposition
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Seong Ho Han, Raphael Edem Agbenyeke, Ga Yeon Lee, Bo Keun Park, Chang Gyoun Kim, Taeyong Eom, Seung Uk Son, Jeong Hwan Han, Ji Yeon Ryu, and Taek-Mo Chung
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Chemistry ,General Chemical Engineering ,General Chemistry ,QD1-999 ,Article - Abstract
A new heteroleptic complex series of tin was synthesized by the salt metathesis reaction of SnX2 (X = Cl, Br, and I) with aminoalkoxide and various N-alkoxy-functionalized carboxamide ligands. The complexes, [ClSn(dmamp)]2 (1), [BrSn(dmamp)]2 (2), and [ISn(dmamp)]2 (3), were prepared from the salt metathesis reaction of SnX2 with one equivalent of dmamp; [Sn(dmamp)(empa)]2 (4), [Sn(dmamp)(mdpa)]2 (5), and [Sn(dmamp)(edpa)]2 (6) were prepared via the salt metathesis reaction using complex 2 with one equivalent of N-alkoxy-functionalized carboxamide ligand. Complexes 1–5 displayed dimeric molecular structures with tin metal centers interconnected by μ2–O bonding via the alkoxy oxygen atom. The molecular structures of complexes 1–5 showed distorted trigonal bipyramidal geometries with lone pair electrons in the equatorial position. Using complex 6 as a tin precursor, SnOx films were deposited by chemical solution deposition (CSD) and subsequent post-deposition annealing (PDA) at high temperatures. SnO and SnO2 films were selectively obtained under controlled PDA atmospheres of argon and oxygen, respectively. The SnO films featured a tetragonal romarchite structure with high crystallinity and a preferred growth orientation along the (101) plane. They also exhibited a lower transmittance of >52% at 400 nm due to an optical band gap of 2.9 eV. In contrast, the SnO2 films exhibited a tetragonal cassiterite crystal structure and an extremely high transmittance of >97% at 400 nm was observed with an optical band gap of 3.6 eV.
- Published
- 2021
5. Synthesis of Heteroleptic Zinc Complexes Containing Aminoalkoxide and β ‐Diketonate Ligands
- Author
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Taek-Mo Chung, Bo Keun Park, Taeyong Eom, Seung Uk Son, Ga Yeon Lee, Seong Ho Han, Na Yeon Kim, and Jeong Min Hwang
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Atomic layer deposition ,Materials science ,chemistry ,Polymer chemistry ,chemistry.chemical_element ,General Chemistry ,Zinc - Published
- 2021
6. Synthesis of New Heteroleptic Indium Complexes as Potential Precursors for Indium Oxide Thin Films
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Bo Keun Park, Sung Kwang Lee, Dagyum Yoo, Seong Ho Han, Seung Uk Son, Chang Gyoun Kim, Taeyong Eom, and Taek-Mo Chung
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Inorganic Chemistry ,chemistry.chemical_compound ,chemistry ,Inorganic chemistry ,Oxide ,chemistry.chemical_element ,Chelation ,Thin film ,Indium - Published
- 2021
7. Atomic layer deposition of a ruthenium thin film using a precursor with enhanced reactivity
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Chan Woo Park, Gun Hwan Kim, Bo Keun Park, Younghun Byun, Taeyong Eom, Seung-Min Han, Seunghun Lee, Seungmin Yeo, Taek-Mo Chung, Jeong Min Hwang, and Hanuel Yang
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Materials science ,Inorganic chemistry ,chemistry.chemical_element ,Substrate (chemistry) ,General Chemistry ,Amorphous solid ,Ruthenium ,Atomic layer deposition ,chemistry ,Materials Chemistry ,Reactivity (chemistry) ,Thin film ,Tin ,Deposition (law) - Abstract
Ruthenium (Ru) thin films were grown via atomic layer deposition (ALD) using a novel Ru precursor with enhanced reactivity, namely Ru(η5-cycloheptadienyl)2 (Ru(chd)2) and O2. Self-limiting growth during the Ru ALD process was achieved by varying the Ru precursor and O2 feeding times. Metallic Ru films with a low resistivity (10–16 μΩ cm) grew at deposition temperatures between 200 and 300 °C, where the growth per cycle (GPC) during Ru ALD was 0.2 to 0.4 A cy−1 at 265 °C. The Ru incubation times were considerably shorter using the novel precursor (negligible on Pt and TiN, ∼22 cycles on SiO2) compared with those associated with Ru ALD using a high-valency Ru precursor and O2. The characteristics of the Ru film were influenced by the substrate. Specifically, the Pt substrate gave rise to an amorphous film, while crystalline films were grown on the TiN and SiO2 substrates, where a high RuOx content resulted on the SiO2 substrate.
- Published
- 2021
8. Enhancement of electrical performance of atomic layer deposited SnO films via substrate surface engineering
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Heenang Choi, Ga Yeon Lee, Ah-Jin Cho, Taeyong Eom, Seong Keun Kim, In-Hwan Baek, Sung Ok Won, Taek-Mo Chung, and Cheol Seong Hwang
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Materials science ,Oxide ,General Chemistry ,Substrate (electronics) ,chemistry.chemical_compound ,Atomic layer deposition ,chemistry ,Chemical engineering ,Impurity ,Materials Chemistry ,Thin film ,Layer (electronics) ,Stoichiometry ,Surface states - Abstract
Atomic layer deposition (ALD) is a technique based on the surface reaction of precursors; thus, it strongly depends on the surface states of the substrate. We demonstrate significant changes in the structural and electrical properties of SnO thin films via modification of substrate surface states. The surface of SiO2 exposed to the atmosphere is usually contaminated by organic compounds and lacks hydroxyl groups. The plasma treatment effectively formed numerous functional groups on SiO2, eventually resulting in significant differences in the growth characteristics and properties of ALD-grown SnO films. In the case of a plasma-treated SiO2 substrate, the SnO layer was fully crystallized at the SnO/SiO2 interface, and the (00l) planes of SnO were aligned parallel to the substrate. The numerous functional groups on the plasma-treated SiO2 promoted a complete reaction on the surface, which resulted in the formation of more stoichiometric SnO containing fewer impurities near the interface. The changes in the interfacial properties by the plasma treatment of SiO2 enhanced the field-effect mobility from 0.7 to 2.0 cm2 V−1 s−1 and reduced the hysteresis voltage. The findings may contribute to the realization of complementary oxide thin film devices in future electronics.
- Published
- 2021
9. Conformational heterogeneity of molecules physisorbed on a gold surface at room temperature
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Mingu Kang, Hyun Woo Kim, Elham Oleiki, Yeonjeong Koo, Hyeongwoo Lee, Jinseong Choi, Taeyong Eom, Geunsik Lee, Yung Doug Suh, and Kyoung-Duck Park
- Abstract
A quantitative single-molecule tip-enhanced Raman spectroscopy (TERS) study at room temperature remained a challenge due to the rapid structural dynamics of molecules exposed to air. Here, we demonstrate the hyperspectral TERS imaging of single or a few brilliant cresyl blue (BCB) molecules at room temperature, along with quantitative spectral analyses. Robust chemical imaging is enabled by the freeze-frame approach using a thin Al2O3 capping layer, which suppresses spectral diffusions and inhibits chemical reactions and contaminations in air. For the molecules resolved spatially in the TERS image, a clear Raman peak variation up to 7.5 cm-1 is observed, which cannot be found in molecular ensembles. From density functional theory-based quantitative analyses of the varied TERS peaks, we reveal the conformational heterogeneity at the single-molecule level. This work provides a facile way to investigate the single-molecule properties in interacting media, expanding the scope of single-molecule vibrational spectroscopy studies.
- Published
- 2021
10. Atomic Layer Deposition of Nanocrystalline-As-Deposited (GeTe)x(Sb2Te3)1–x Films for Endurable Phase Change Memory
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Chanyoung Yoo, Yoon Kyeung Lee, Manick Ha, Woohyun Kim, Eui-Sang Park, Taeyong Eom, Jeong Woo Jeon, and Cheol Seong Hwang
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Materials science ,General Chemical Engineering ,02 engineering and technology ,General Chemistry ,010402 general chemistry ,021001 nanoscience & nanotechnology ,01 natural sciences ,Nanocrystalline material ,0104 chemical sciences ,Deposition temperature ,Phase-change memory ,Atomic layer deposition ,Chemical engineering ,Materials Chemistry ,0210 nano-technology - Abstract
This paper introduces a new atomic layer deposition process for highly conformal, nanocrystalline-as-deposited GeTe–Sb2Te3 pseudobinary film growth at a deposition temperature of 130 °C. The proces...
- Published
- 2019
11. Comprehensive analysis of multi-class mycotoxins in twenty different species of functional and medicinal herbs using liquid chromatography–tandem mass spectrometry
- Author
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Taeyong Eom, Jung-Hyun Kim, Junhee Kim, Seung Muk Hyun, Sang Beom Han, Shi Feng, Hyun-Deok Cho, Joon Hyuk Suh, and Yu Wang
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Ochratoxin A ,Aflatoxin ,Chromatography ,Chemistry ,010401 analytical chemistry ,Extraction (chemistry) ,04 agricultural and veterinary sciences ,Mass spectrometry ,Quechers ,Orbitrap ,040401 food science ,01 natural sciences ,0104 chemical sciences ,law.invention ,chemistry.chemical_compound ,0404 agricultural biotechnology ,Liquid chromatography–mass spectrometry ,law ,Sample preparation ,Food Science ,Biotechnology - Abstract
Analysis of mycotoxins in functional and medicinal herbs is a challenge because herbs have complicated and diverse matrices from different parts of plants as well as different species. Here, we introduce a rapid and comprehensive liquid chromatography–tandem mass spectrometry method for the determination of multi-class mycotoxins (aflatoxin B1, B2, G1, G2, ochratoxin A, zearalenone, deoxynivalenol, fumonisin B1, B2, B3 and T-2 toxin) in twenty different species of herbs that are used for both food and medicinal purposes. Various sample preparation methods were compared and optimized to obtain satisfactory extraction of mycotoxins in different matrices. The extraction efficiency was found to vary from not only extraction methods but also matrix types, demonstrating the complexity of herbal matrix. On the basis of optimization results, immunoaffinity column was selected as an extraction method to cover all types of samples. QuEChERS was also employed as a supplementary method to support the immunoaffinity column method. The developed method was validated by assessing specificity, linearity, precision, recovery, limit of quantification and uncertainty, and applied in a hundred of real samples to monitor target mycotoxins. The monitoring results were further verified using accurate high resolution mass measurements by Orbitrap mass spectrometry. As far as we know, this is the first time the multi-class mycotoxins were determined in a broad range of functional and medicinal herb matrices, with high selectivity and sensitivity. In addition, the proposed method was proven to be more efficient and sensitive than other methods.
- Published
- 2019
12. Strategic allocation of two-dimensional van der Waals semiconductor as an oxygen reservoir for boosting resistive switching reliability
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Heenang Choi, Bo Keun Park, Gun Hwan Kim, Taek-Mo Chung, Raphael Edem Agbenyeke, Wooseok Song, Doo Seok Jeong, Jin Joo Ryu, Seung-Jong Yoo, Taeyong Eom, and Kanghyeok Jeon
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Materials science ,business.industry ,Oxide ,General Physics and Astronomy ,Surfaces and Interfaces ,General Chemistry ,Condensed Matter Physics ,Surfaces, Coatings and Films ,symbols.namesake ,chemistry.chemical_compound ,Reliability (semiconductor) ,Semiconductor ,chemistry ,Homogeneity (physics) ,symbols ,Optoelectronics ,van der Waals force ,business ,Anisotropy ,Layer (electronics) ,Voltage - Abstract
2-dimensional materials are highlighted in various electronic device applications due to their tunable and unique anisotropic physical characteristics induced by inherent low-dimensional nature. Herein, a 2-dimensional layered structure of SnS2 is rationally adopted as an oxygen reservoir layer in a typical transition metal oxide based resistive switching device. The resistive switching media of stacked SnS2/TiO2 and lamella-like SnS2·TiO2 show 100 and 250 times higher endurance characteristics than that of individual TiO2 based resistive switching device, respectively. Additionally, the characteristic of the operation voltage distribution for resistive switching also exhibits improved homogeneity in SnS2-incorporated devices. Through the various microscopic analyses, it is revealed that the SnS2 can store the mobile oxygen ions from TiO2 in its interlayer, which facilitates boosted resistive switching characteristics. The oxygen reservoir layer is a crucial prerequisite for a reliable resistive switching device, however, the choice of materials that can serve as an oxygen reservoir is limited depending on the specific resistive switching system being used. This study demonstrates the 2-dimensional materials can be an unprecedented candidate for oxygen reservoir layers in resistive switching devices.
- Published
- 2022
13. Atomic Layer Deposition of GeTe and Ge–Sb–Te Films Using HGeCl3, Sb(OC2H5)3, and {(CH3)3Si}2Te and Their Reaction Mechanisms
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Cheol Seong Hwang, Chanyoung Yoo, Sergei A. Ivanov, Sang Gyun Kim, Taehong Gwon, Eui-Sang Park, Taeyong Eom, Moo-Sung Kim, Manchao Xiao, Sijung Yoo, and Iain Buchanan
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Reaction mechanism ,Materials science ,General Chemical Engineering ,02 engineering and technology ,General Chemistry ,Substrate (electronics) ,GeSbTe ,010402 general chemistry ,021001 nanoscience & nanotechnology ,01 natural sciences ,0104 chemical sciences ,Phase-change memory ,chemistry.chemical_compound ,Crystallography ,Atomic layer deposition ,chemistry ,Materials Chemistry ,Thin film ,0210 nano-technology ,Ternary operation ,Stoichiometry - Abstract
In this paper, a new atomic layer deposition (ALD) process for depositing binary GeTe and ternary Ge–Sb–Te thin films is reported, where HGeCl3 and ((CH3)3Si)2Te were used as Ge and Te precursors, respectively. The precursors reacted together to form the films at a low substrate temperature of 50–100 °C, without involving any additional reactive process gas. HCl elimination from the Ge precursor to form the divalent Ge intermediate, GeCl2, is proposed to explain the formation of 1:1 composition stoichiometric GeTe films. The GeTe films are promising for use in phase change memory applications. Ternary Ge–Sb–Te films were deposited by combining the GeTe ALD process with a previously developed ALD process for Sb2Te3 films, where Sb(OC2H5)3 and ((CH3)3Si)2Te were employed respectively as the Sb and Te precursors. However, the composition of the ternary GeSbTe films deviated slightly from the desired GeTe–Sb2Te3 pseudobinary composition suggesting that a certain unwanted reaction was involved between the prev...
- Published
- 2017
14. Synthesis of novel volatile niobium precursors containing carboxamide for Nb2O5 thin films
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Ji Hun Lee, Sunyoung Shin, Chang Gyoun Kim, Jeong Min Hwang, Na Yeon Kim, Taeyong Eom, Ji Yeon Ryu, Bo Keun Park, and Taek-Mo Chung
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Thermogravimetric analysis ,Denticity ,010405 organic chemistry ,Chemistry ,medicine.drug_class ,Carboxamide ,Carbon-13 NMR ,010402 general chemistry ,01 natural sciences ,0104 chemical sciences ,Inorganic Chemistry ,chemistry.chemical_compound ,Pentagonal bipyramidal molecular geometry ,Polymer chemistry ,Pyridine ,Materials Chemistry ,medicine ,Salt metathesis reaction ,Physical and Theoretical Chemistry ,Single crystal - Abstract
A series of novel Nb(V) tBu-imido/N-alkoxy carboxamide complexes, NbCl2(NtBu)(pyridine)(edpa) (1), NbCl2(NtBu)(pyridine)(mdpa) (2), and Nb(NtBu)(mdpa)3 (3), were successfully synthesized by metathesis reaction between Nb(NtBu)Cl3(py)2 and several equivalents of Na(edpa) (edpaH = Nethoxy-2,2-dimethylpropanamide) and Na(mdpa) (mdpaH = N-methoxy-2,2-dimethylpropanamide). These complexes could potentially serve as precursors for Nb-containing thin films. Compounds 1–3 were characterized by FT-IR and 1H and 13C NMR spectroscopies, elemental analysis, and thermogravimetric analysis (TGA). Single crystal X-ray diffraction analysis suggested that complex 3 has a distorted pentagonal bipyramidal geometry around the central Nb atom, with three bidentate mdpa ligands and one tBu imido group saturating the coordination. TGA analysis revealed that the thermal characteristics of 3 were superior to those of 1 and 2. All prepared complexes were able to be distilled or sublimed and expected potential precursors for the fabrication of thin films.
- Published
- 2021
15. Multiclass mycotoxin analysis in edible oils using a simple solvent extraction method and liquid chromatography with tandem mass spectrometry
- Author
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Hyun-Deok Cho, Jung-Hyun Kim, Moosung Kim, Jinyoung An, Mihee Park, Sang Beom Han, Sheen-Hee Kim, and Taeyong Eom
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Electrospray ,Liquid Phase Microextraction ,Health, Toxicology and Mutagenesis ,Toxicology ,Mass spectrometry ,Tandem mass spectrometry ,Quechers ,01 natural sciences ,0404 agricultural biotechnology ,Tandem Mass Spectrometry ,Liquid chromatography–mass spectrometry ,Plant Oils ,Sample preparation ,Detection limit ,Chromatography ,Chemistry ,010401 analytical chemistry ,Selected reaction monitoring ,Public Health, Environmental and Occupational Health ,04 agricultural and veterinary sciences ,General Chemistry ,General Medicine ,Mycotoxins ,040401 food science ,0104 chemical sciences ,Solvents ,Plants, Edible ,Chromatography, Liquid ,Food Science - Abstract
A simple and rapid method for the simultaneous determination of 11 mycotoxins – aflatoxins B1, B2, G1 and G2; fumonisins B1, B2 and B3; ochratoxin A; zearalenone; deoxynivalenol; and T-2 toxin – in edible oils was established using liquid chromatography tandem mass spectrometry (LC-MS/MS). In this study, QuEChERS (Quick, Easy, Cheap, Effective, Rugged and Safe), QuEChERS with dispersive liquid–liquid microextraction, and solvent extraction were examined for sample preparation. Among these methods, solvent extraction with a mixture of formic acid/acetonitrile (5/95, v/v) successfully extracted all target mycotoxins. Subsequently, a defatting process using n-hexane was employed to remove the fats present in the edible oil samples. Mass spectrometry was carried out using electrospray ionisation in polarity switching mode with multiple reaction monitoring. The developed LC-MS/MS method was validated by assessing the specificity, linearity, recovery, limit of quantification (LOQ), accuracy and precisio...
- Published
- 2017
16. Buffer Layers: Copper Oxide Buffer Layers by Pulsed‐Chemical Vapor Deposition for Semitransparent Perovskite Solar Cells (Adv. Mater. Interfaces 1/2021)
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Songhee Kim, Helen Hejin Park, Taek-Mo Chung, Taeyong Eom, Young Lee, Hyunmin Jung, Seon Min Shin, Raphael Edem Agbenyeke, Jangwon Seo, Chang Gyoun Kim, and Nam Joong Jeon
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Copper oxide ,chemistry.chemical_compound ,Materials science ,Chemical engineering ,chemistry ,Mechanics of Materials ,Mechanical Engineering ,Chemical vapor deposition ,Buffer (optical fiber) ,Perovskite (structure) - Published
- 2021
17. Copper Oxide Buffer Layers by Pulsed‐Chemical Vapor Deposition for Semitransparent Perovskite Solar Cells
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Helen Hejin Park, Songhee Kim, Raphael Edem Agbenyeke, Jangwon Seo, Taeyong Eom, Taek-Mo Chung, Seon Min Shin, Nam Joong Jeon, Young Lee, Hyunmin Jung, and Chang Gyoun Kim
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Copper oxide ,chemistry.chemical_compound ,Materials science ,Chemical engineering ,chemistry ,Mechanics of Materials ,Mechanical Engineering ,Chemical vapor deposition ,Buffer (optical fiber) ,Perovskite (structure) - Published
- 2020
18. Atomic Layer Deposition of GeTe Films Using Ge{N[Si(CH3)3]2}2, {(CH3)3Si}2Te, and Methanol
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Sijung Yoo, Manchao Xiao, Sergei Vladimirovich Ivanov, Deok-Yong Cho, Iain Buchanan, Cheol Seong Hwang, Taehong Gwon, Taeyong Eom, Moo-Sung Kim, and Han-Koo Lee
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Materials science ,Hydrogen ,020209 energy ,General Chemical Engineering ,Analytical chemistry ,chemistry.chemical_element ,02 engineering and technology ,General Chemistry ,Chemical reaction ,chemistry.chemical_compound ,Crystallography ,Atomic layer deposition ,chemistry ,Oxidation state ,0202 electrical engineering, electronic engineering, information engineering ,Materials Chemistry ,Wafer ,Reactivity (chemistry) ,Methanol ,Thin film - Abstract
In this report, a new method to deposit GeTe thin film by atomic layer deposition (ALD) is described. Ge(N(Si(CH3)3)2)2, in which Ge is in +2 oxidation state, and ((CH3)3Si)2Te were used as Ge and Te precursors, respectively. GeTe films were deposited at a low wafer temperature of 70–120 °C. To improve low reactivity of Ge(N(Si(CH3)3)2)2 toward ALD-type reaction with ((CH3)3Si)2Te, methanol vapor was coinjected with the Ge precursor and the Te precursor to form a reactive Ge intermediate having methoxy ligands and a Te intermediate having hydrogen ligands in the gas phase. This chemistry-specific ALD process deposited films various compositional GeTe alloys including the desired composition of Ge:Te = 1:1. Detailed mechanism study on the probable chemical reactions and film composition analysis revealed that the film growth could proceed via the formations of GeTe2, GeTe, and Ge2Te phases depending on the relative Ge-precursor concentration during the ALD process. The films showed feasibility for phase-ch...
- Published
- 2016
19. Multicolor Changeable Optical Coating by Adopting Multiple Layers of Ultrathin Phase Change Material Film
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Cheol Seong Hwang, Sijung Yoo, Taeyong Eom, Sang Gyun Kim, and Taehong Gwon
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010302 applied physics ,Phase transition ,Materials science ,business.industry ,02 engineering and technology ,Optical storage ,021001 nanoscience & nanotechnology ,01 natural sciences ,Phase-change material ,Atomic and Molecular Physics, and Optics ,Electronic, Optical and Magnetic Materials ,Amorphous solid ,law.invention ,Optical coating ,Optics ,law ,Optical cavity ,0103 physical sciences ,Optoelectronics ,Electrical and Electronic Engineering ,Crystallization ,0210 nano-technology ,business ,Layer (electronics) ,Biotechnology - Abstract
The multilayered optical coating whose structure consists of optical cavity and multiple layers of ultrathin phase change material (PCM) film is presented. The color changing is enabled via transition between amorphous and crystalline phases of PCM, which is accompanied by high optical contrast. The phase transition of each PCM layer, separated by ultrathin oxide barrier, can be realized through various crystallization temperatures with respect to the different thickness of ultrathin (
- Published
- 2016
20. Comparative Study on the Gate‐Induced Electrical Instability of p‐Type SnO Thin‐Film Transistors with SiO 2 and Al 2 O 3 /SiO 2 Gate Dielectrics
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Jun Shik Kim, Wha-Young Kim, Sang Yoon Lee, Taek-Mo Chung, Jihun Kim, Younjin Jang, Na Yeon Kim, Kwangmin Kim, Yonghee Lee, Woojin Jeon, Sukin Kang, Heenang Choi, Cheol Seong Hwang, and Taeyong Eom
- Subjects
Materials science ,business.industry ,Thin-film transistor ,Optoelectronics ,General Materials Science ,Dielectric ,Electrical instability ,Condensed Matter Physics ,business ,Threshold voltage - Published
- 2020
21. Aquilanols A and B, Macrocyclic Humulene-Type Sesquiterpenoids from the Agarwood of Aquilaria malaccensis
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Taeyong Eom, Ki-Bong Oh, Tae Ryong Kim, Sung Won Kwon, Jeong Hill Park, Chi Thanh Ma, Sang Beom Han, Bo Wu, and Eunji Cho
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Staphylococcus aureus ,Stereochemistry ,Molecular Conformation ,Pharmaceutical Science ,Crystallographic data ,Stereoisomerism ,Microbial Sensitivity Tests ,engineering.material ,010402 general chemistry ,Ring (chemistry) ,Crystallography, X-Ray ,01 natural sciences ,Analytical Chemistry ,chemistry.chemical_compound ,Drug Discovery ,Enterococcus faecalis ,Escherichia coli ,Organic chemistry ,Nuclear Magnetic Resonance, Biomolecular ,Aquilaria malaccensis ,Chromatography, High Pressure Liquid ,Pharmacology ,Hplc analysis ,Bicyclic molecule ,biology ,Humulene ,Molecular Structure ,010405 organic chemistry ,Chemistry ,Organic Chemistry ,Salmonella enterica ,Agarwood ,biology.organism_classification ,Wood ,0104 chemical sciences ,Monocyclic Sesquiterpenes ,Klebsiella pneumoniae ,Complementary and alternative medicine ,Laos ,Thymelaeaceae ,engineering ,Molecular Medicine ,Cholinesterase Inhibitors ,Sesquiterpenes ,Algorithms - Abstract
Four new and five known sesquiterpenoids were isolated from the agarwood of Aquilaria malaccensis. Aquilanols A and B (1 and 2) have an unprecedented macrocyclic humulene structure with a bicyclic 7/10 ring system. Compound 2 was obtained as a scalemic mixture that was resolved by HPLC analysis using a chiral column. Their structures were deduced based on spectroscopic data analysis, and the absolute configurations were unambiguously determined by X-ray crystallographic data and ECD spectroscopic analysis. A putative biosynthetic pathway of these sesquiterpenoids is proposed.
- Published
- 2017
22. Improved Initial Growth Behavior of SrO and SrTiO3 Films Grown by Atomic Layer Deposition Using {Sr(demamp)(tmhd)}2 as Sr-Precursor
- Author
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Jeong Hwan Han, Chang Gyoun Kim, Cheol Hyun An, Woojin Jeon, Woongkyu Lee, Cheol Seong Hwang, Han Joon Kim, Min Jung Chung, Taek-Mo Chung, Bo Keun Park, Taeyong Eom, Sang Woon Lee, and Sheby Mary George
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General Chemical Engineering ,Analytical chemistry ,chemistry.chemical_element ,Nanotechnology ,General Chemistry ,Oxygen ,Active oxygen ,Atomic layer deposition ,chemistry ,Electrode ,Materials Chemistry ,Reactivity (chemistry) ,Growth rate ,Thin film ,Layer (electronics) - Abstract
An atomic layer deposition (ALD) process for SrTiO3 (STO) thin film growth was developed using a newly designed and synthesized heteroleptic Sr-precursor, {Sr(demamp)(tmhd)}2 (demampH = 1-{[2-(dimethylamino)ethyl](methyl)amino}-2-methylpropan-2-ol, tmhdH = 2,2,6,6-tetramethyl-3,5-heptanedione), which offered an intermediate reactivity toward oxygen between Sr(tmhd)2 and Sr(iPr3Cp)2. Because of the appropriate reactivity of {Sr(demamp)(tmhd)}2 toward oxygen, the abnormal initial growth behavior (due to interaction between the Sr-precursor and active oxygen contained in the underlying oxidized Ru layer) became negligible during the growth of the SrO and STO films on the Ru electrode, which allowed the growth of the SrO and STO films to be highly controllable with a moderate growth rate. Using Ti(CpMe5)(OMe)3 as the Ti-precursor and O3 as the oxygen source in the TiO2 ALD subcycle, the ALD process of the STO film revealed a growth rate of 0.05 nm/cycle and ∼85% of step coverage in terms of the thickness and ...
- Published
- 2015
23. Combined Ligand Exchange and Substitution Reactions in Atomic Layer Deposition of Conformal Ge2Sb2Te5 Film for Phase Change Memory Application
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Manchao Xiao, Taeyong Eom, Byung Joon Choi, Iain Buchanan, Sergei Vladimirovich Ivanov, Moo-Sung Kim, Sijung Yoo, Taehong Gwon, and Cheol Seong Hwang
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Substitution reaction ,Chemistry ,Ligand ,General Chemical Engineering ,Analytical chemistry ,Nanotechnology ,Conformal map ,General Chemistry ,Substrate (electronics) ,Contact hole ,Phase-change memory ,Atomic layer deposition ,Materials Chemistry ,Layer (electronics) - Abstract
For phase change memories application, Ge–Sb–Te films were prepared by a stable and reliable atomic layer deposition (ALD) method. Ge(OC2H5)4, Sb(OC2H5)3, [(CH3)3Si]3Sb, and [(CH3)3Si]2Te were used to deposit various layers with compositions that can be described by combinations of GeTe2–Sb2Te layers including Ge2Sb2Te5 at a substrate temperature as low as 70 °C. A shift in composition of Sb–Te films from Sb2Te3 to Sb2Te composition was achieved by combining ligand exchange and substitution reaction between Sb in [(CH3)3Si]3Sb and Te in the Sb2Te3 layer. This surface-limited ALD process allowed highly conformal, smooth, and reproducible film growth over a contact hole structure, highlighting the feasibility of phase change memory applications.
- Published
- 2015
24. Chemical interaction and ligand exchange between a [(CH3)3Si]3Sb precursor and atomic layer deposited Sb2Te3 films
- Author
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Sijung Yoo, Sergei Vladimirovich Ivanov, Byung Joon Choi, Moo-Sung Kim, Taeyong Eom, Manchao Xiao, Iain Buchanan, Taehong Gwon, Andrew Adamczyk, and Cheol Seong Hwang
- Subjects
Materials science ,Trimethylsilyl ,Ligand ,General Chemistry ,Chemical interaction ,Crystallography ,chemistry.chemical_compound ,chemistry ,Materials Chemistry ,Organic chemistry ,Thin film ,Ternary operation ,Chemical composition ,Layer (electronics) ,Tie line - Abstract
The chemical interaction between the [(CH3)3Si]3Sb precursor and atomic layer deposited Sb2Te3 thin films was examined at temperatures ranging from 70 to 220 °C. The trimethylsilyl group [(CH3)3Si] displays greater affinity for Te than for Sb, and this drives replacement of Te in the film with Sb from the [(CH3)3Si]3Sb precursor, while eliminating volatile [(CH3)3Si]2Te, especially at elevated temperatures. The compositions of the resulting Sb–Te layers lie on the Sb2Te3–Sb tie line. The incorporation behavior of [(CH3)3Si]3Sb was explained in terms of a Lewis acid–base reaction. The exchange reactions occurred to relieve the unfavorable hard–soft Lewis acid–base pair between the trimethylsilyl group and Sb in [(CH3)3Si]3Sb. Such a reaction could be usefully adopted to control the chemical composition of ternary Ge–Sb–Te thin films.
- Published
- 2015
25. Bipolar resistive switching behavior of an amorphous Ge2Sb2Te5thin films with a Te layer
- Author
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Taeyong Eom, Cheol Seong Hwang, Sijung Yoo, and Taehong Gwon
- Subjects
Materials science ,business.industry ,Transmission electron microscopy ,Electric field ,Electrode ,Optoelectronics ,General Materials Science ,Thin film ,Thermal conduction ,business ,Electrical conductor ,Amorphous solid ,Ion - Abstract
The mechanism of bipolar resistive switching (BRS) of amorphous Ge2Sb2Te5 (GST) thin films sandwiched between inert electrodes (Ti and Pt) was examined. Typical bipolar resistive switching behavior with a high resistance ratio (∼103) and reliable switching characteristics was achieved. High-resolution transmission electron microscopy revealed the presence of a conductive Te-filament bridging between the top and bottom electrodes through an amorphous GST matrix. The conduction mechanism analysis showed that the low-resistance state was semiconducting and dominated by band transport, whereas Poole–Frenkel conduction governed the carrier transport in the high-resistance state. Thus, the BRS behavior can be attributed to the formation and rupture of the semiconducting conductive Te bridge through the migration of the Te ions in the amorphous GST matrix under a high electric field. The Te ions are provided by the thin (∼5 nm) Te-rich layer formed at the bottom electrode interface.
- Published
- 2015
26. Development of aqueous mobile phase using chaotrope for the chromatographic determination of melamine in infant formula
- Author
-
Yu Wang, Byeonghee Kim, Juhee Jung, Jung-Hyun Kim, Taeyong Eom, Sang Beom Han, Mihee Park, Joon Hyuk Suh, and Hyun-Deok Cho
- Subjects
Sodium hexafluorophosphate ,Analytical chemistry ,Ionic Liquids ,010402 general chemistry ,01 natural sciences ,Biochemistry ,Analytical Chemistry ,chemistry.chemical_compound ,Column chromatography ,Phase (matter) ,Humans ,Chromatography, High Pressure Liquid ,Micelles ,Chromatography, Reverse-Phase ,Chromatography ,Aqueous solution ,Chemistry ,Triazines ,010401 analytical chemistry ,Organic Chemistry ,Infant ,Reproducibility of Results ,Green Chemistry Technology ,General Medicine ,Reversed-phase chromatography ,Infant Formula ,0104 chemical sciences ,Chaotropic agent ,Ionic liquid ,Solvents ,Melamine ,Food Analysis - Abstract
Direct analysis of melamine using reverse phase chromatography is a challenge because this compound's small size and strong polar nature leads to abnormal peak symmetry as well as poor retention. Here, we introduce a simple and reliable reverse phase liquid chromatographic method using sodium hexafluorophosphate to modify an acidic aqueous eluent, resulting in improved chromatographic behaviors of melamine in complex food matrices. Variables affecting the retention mechanism, including chaotrope type, concentration and stationary phase, were investigated. Under optimum conditions, melamine retention, separation efficiency, peak shape and reproducibility were significantly improved as compared to other methods that use ionic liquids or a micellar mobile phase. No interference affected melamine detection when infant formula was applied as the food matrix. Analytical reliability was demonstrated through estimation of validation parameters such as specificity, linearity, precision, accuracy and recovery. This method is suitable for routine analysis of melamine in infant formula. More noteworthy, this is the first time that an organic solvent-free mobile phase using chaotropic salt, meeting the concept of green chemistry, has been proposed.
- Published
- 2017
27. Influence of the Kinetic Adsorption Process on the Atomic Layer Deposition Process of (GeTe2)(1–x)(Sb2Te3)x Layers Using Ge4+–Alkoxide Precursors
- Author
-
Moo-Sung Kim, Sijung Yoo, Byung Joon Choi, Taeyong Eom, Manchao Xiao, Iain Buchanan, Taehong Gwon, and Cheol Seong Hwang
- Subjects
General Chemical Engineering ,Nanotechnology ,General Chemistry ,Desorption kinetics ,chemistry.chemical_compound ,Atomic layer deposition ,Adsorption ,chemistry ,Physisorption ,Adsorption kinetics ,Scientific method ,Alkoxide ,Materials Chemistry ,Physical chemistry ,Layer (electronics) - Abstract
(GeTe2)(1–x)(Sb2Te3)x (GST) layers were deposited via atomic layer deposition (ALD) at growth temperatures ranging from 50 to 120 °C using Ge(OCH3)4 or Ge(OC2H5)4, Sb(OC2H5)3, and [(CH3)3Si]2Te as the metal–organic precursors of the Ge, Sb, and Te elements, respectively. The GST layers with compositions lying on the GeTe2–Sb2Te3 tie lines could be obtained by varying the ratio of the Ge–Te and Sb–Te ALD cycles. Although the incorporation of an Sb–Te layer into the GST film occurred in a genuine ALD manner, that of the Ge–Te layer was governed by the kinetically limited physisorption of Ge precursors. The incorporation behavior of the Ge precursor with different ligands was explained by the adsorption and desorption kinetics based on the Brunauer–Emmett–Teller isotherm. The ALD-like film growth behavior could be well-explained by the kinetically limited incorporation of Ge atoms.
- Published
- 2014
28. Effect of Electrode Material on the Crystallization of GeTe Grown by Atomic Layer Deposition for Phase Change Random Access Memory
- Author
-
In Hyuk Im, Chanyoung Yoo, Byung Joon Choi, Sung Yeon Ryu, Taeyong Eom, Yong Kim, Seok Choi, Seung Ik Oh, and Cheol Seong Hwang
- Subjects
Materials science ,phase change random access memory ,lcsh:Mechanical engineering and machinery ,Kinetics ,Nucleation ,chemistry.chemical_element ,02 engineering and technology ,010402 general chemistry ,01 natural sciences ,Article ,law.invention ,Atomic layer deposition ,Thermal conductivity ,law ,lcsh:TJ1-1570 ,Electrical and Electronic Engineering ,Crystallization ,Composite material ,Mechanical Engineering ,electrode interfacial layer effect ,Johnson–Mehl–Avrami kinetics ,021001 nanoscience & nanotechnology ,0104 chemical sciences ,chemistry ,Control and Systems Engineering ,Electrode ,crystallization behavior ,0210 nano-technology ,Tin ,Voltage - Abstract
The electrical switching behavior of the GeTe phase-changing material grown by atomic layer deposition is characterized for the phase change random access memory (PCRAM) application. Planar-type PCRAM devices are fabricated with a TiN or W bottom electrode (BE). The crystallization behavior is characterized by applying an electrical pulse train and analyzed by applying the Johnson&ndash, Mehl&ndash, Avrami kinetics model. The device with TiN BE shows a high Avrami coefficient (>, 4), meaning that continuous and multiple nucleations occur during crystallization (set switching). Meanwhile, the device with W BE shows a smaller Avrami coefficient (~3), representing retarded nucleation during the crystallization. In addition, larger voltage and power are necessary for crystallization in case of the device with W BE. It is believed that the thermal conductivity of the BE material affects the temperature distribution in the device, resulting in different crystallization kinetics and set switching behavior.
- Published
- 2019
29. Influences of metal, non-metal precursors, and substrates on atomic layer deposition processes for the growth of selected functional electronic materials
- Author
-
Seul Ji Song, Byung Joon Choi, Jeong Hwan Han, Sang Woon Lee, Seong Keun Kim, Cheol Seong Hwang, Taeyong Eom, and Woongkyu Lee
- Subjects
Chemistry ,Non-blocking I/O ,Nanotechnology ,Substrate (electronics) ,Dielectric ,engineering.material ,Inorganic Chemistry ,Atomic layer deposition ,Electrode ,Materials Chemistry ,engineering ,Noble metal ,Physical and Theoretical Chemistry ,Thin film ,Solid solution - Abstract
Atomic layer deposition (ALD) is known for its self-limiting reaction, which offers atomic-level controllability of the growth of thin films for a wide range of applications. The self-limiting mechanism leads to very useful properties, such as excellent uniformity over a large area and superior conformality on complex structures. These unique features of ALD provide promising opportunities for future electronics. Though the ALD of Al2O3 film (using trimethyl-aluminum and water as a metal precursor and oxygen source, respectively) can be regarded as a representative example of an ideal ALD based on the completely self-limiting reaction, there are many cases deviating from the ideal ALD reaction in recently developed ALD processes. The nonconventional aspects of the ALD reactions may strongly influence the various properties of the functional materials grown by ALD, and the lack of comprehension of these aspects has made ALD difficult to control. In this respect, several dominant factors that complicate ALD reactions, including the types of metal precursors, non-metal precursors (oxygen sources or reducing agents), and substrates, are discussed in this review. The examination of such aspects may contribute to the further understanding of non-ideal ALD reactions. Several functional materials for future electronics, such as higher-k dielectrics (TiO2, SrTiO3), phase change materials (Ge–Sb–Te solid solution), noble metal electrodes (Ru, RuO2), and resistive switching materials (NiO), are addressed in this review. Finally, desirable directions of ALD are suggested with consideration of the uncommon and non-ideal aspects of the ALD reactions.
- Published
- 2013
30. Conformal Formation of (GeTe2)(1–x)(Sb2Te3)x Layers by Atomic Layer Deposition for Nanoscale Phase Change Memories
- Author
-
Byung Joon Choi, Seol Choi, Manchao Xiao, Iain Buchanan, Deok-Yong Cho, Taehong Gwon, Sang Ho Rha, Woongkyu Lee, Min Hwan Lee, Cheol Seong Hwang, Moo-Sung Kim, and Taeyong Eom
- Subjects
Materials science ,Chalcogenide ,General Chemical Engineering ,Nanotechnology ,General Chemistry ,Substrate (electronics) ,chemistry.chemical_compound ,Atomic layer deposition ,Adsorption ,Chemical engineering ,chemistry ,Physisorption ,Chemisorption ,Phase (matter) ,Materials Chemistry ,Thin film - Abstract
Phase change random access memory appears to be the strongest candidate for next-generation high density nonvolatile memory. The fabrication of ultrahigh density phase change memory (≫1 Gb) depends heavily on the thin film growth technique for the phase changing chalcogenide material, most typically containing Ge, Sb and Te (Ge–Sb–Te). Atomic layer deposition (ALD) at low temperatures is the most preferred growth method for depositing such complex materials over surfaces possessing extreme topology. In this study, [(CH3)3Si]2Te and stable alkoxy-Ge (Ge(OCH3)4) and alkoxy-Sb (Sb(OC2H5)3) metal–organic precursors were used to deposit various layers with compositions lying on the GeTe2–Sb2Te3 tie lines at a substrate temperature as low as 70 °C using a thermal ALD process. The adsorption of Ge precursor was proven to be a physisorption type while other precursors showed a chemisorption behavior. However, the adsorption of Ge precursor was still self-regulated, and the facile ALD of the pseudobinary solid sol...
- Published
- 2012
31. Growth and Phase Separation Behavior in Ge-Doped Sb−Te Thin Films Deposited by Combined Plasma-Enhanced Chemical Vapor and Atomic Layer Depositions
- Author
-
Seol Choi, Jae Hyuck Jang, Woongkyu Lee, Byung Joon Choi, Cheol Seong Hwang, and Taeyong Eom
- Subjects
Materials science ,Doping ,Analytical chemistry ,Concentration ratio ,Surfaces, Coatings and Films ,Electronic, Optical and Magnetic Materials ,Amorphous solid ,law.invention ,General Energy ,Electrical resistivity and conductivity ,law ,Wafer ,Physical and Theoretical Chemistry ,Thin film ,Bond energy ,Crystallization - Abstract
The growth, phase separation, crystallization behavior, and electrical properties of various Ge-doped Sb−Te thin films were examined. The films were deposited by combined plasma-enhanced chemical vapor and atomic layer depositions at a wafer temperature of 150 °C using Ge(i-C4H9)4, Sb(i-C3H7)3, and Te(i-C3H7)2 as the precursors for Ge, Sb, and Te, respectively. The different compositions were obtained by adjusting the Ge and Sb precursor injection times. Segregated crystalline Sb islands were observed in amorphous Sb-rich Sb−Te thin films containing over 10 atom % of Ge. The crystallization kinetics of the Ge-doped SbTe alloys, which depends on the concentration ratio of Sb/Te and the bond energy between Ge, Sb, and Te, provide clues to help understand the phase separation behavior of the films at growth temperature. Ge17Sb58Te25 and Ge31Sb38Te31 showed the highest resistivity of 67 Ω cm at the as-deposited state and exhibited a crystallization temperature of ∼260 °C.
- Published
- 2010
32. Influence of Substrates on the Nucleation and Growth Behaviors of Ge2Sb2Te5 Films by Combined Plasma-Enhanced Atomic Layer and Chemical Vapor Deposition
- Author
-
Seol Choi, Seung Wook Ryu, Byung Joon Choi, Cheol Seong Hwang, Suk Kyoung Hong, Deok-Yong Cho, Jaeyeong Heo, Hyeong Joon Kim, Taeyong Eom, and Yoon-Jung Kim
- Subjects
Materials science ,General Chemical Engineering ,Nucleation ,chemistry.chemical_element ,Substrate (chemistry) ,General Chemistry ,Chemical vapor deposition ,Nitride ,Atomic layer deposition ,Chemical engineering ,chemistry ,Materials Chemistry ,Thin film ,Tin ,Layer (electronics) - Abstract
This study concerned the effect of the substrate on the nucleation and growth behavior of Ge2Sb2Te5 (GST) thin films deposited by a combination of plasma-enhanced chemical vapor deposition (for Sb and Te) and plasma-enhanced atomic layer deposition (for Ge) processes at wafer temperatures ranging from 100 to 200 °C using Ge(i-C4H9)4, Sb(i-C3H7)3, and Te(i-C3H7)2 as the Ge, Sb, and Te precursors, respectively. Several oxide and nitride layers that were formed on the Si substrate were concerned as substrates. The nucleation of the GST films on the SiO2, Si3N4, and ZrO2 substrates was seriously retarded (long incubation cycles) compared to those on the TiN and TiO2 substrates, where smooth film growth with negligible incubation cycles was achieved. The GST film did not grow at all on the HfO2 substrate. The reason for the enhanced nucleation and growth properties of GST on the TiO2 and TiN (partially oxidized) substrates was related to the formation of a GeO2 phase and the charge exchange effect of a partial...
- Published
- 2009
33. Bipolar resistive switching behavior of an amorphous Ge₂Sb₂Te₅ thin films with a Te layer
- Author
-
Sijung, Yoo, Taeyong, Eom, Taehong, Gwon, and Cheol Seong, Hwang
- Abstract
The mechanism of bipolar resistive switching (BRS) of amorphous Ge2Sb2Te5 (GST) thin films sandwiched between inert electrodes (Ti and Pt) was examined. Typical bipolar resistive switching behavior with a high resistance ratio (∼10(3)) and reliable switching characteristics was achieved. High-resolution transmission electron microscopy revealed the presence of a conductive Te-filament bridging between the top and bottom electrodes through an amorphous GST matrix. The conduction mechanism analysis showed that the low-resistance state was semiconducting and dominated by band transport, whereas Poole-Frenkel conduction governed the carrier transport in the high-resistance state. Thus, the BRS behavior can be attributed to the formation and rupture of the semiconducting conductive Te bridge through the migration of the Te ions in the amorphous GST matrix under a high electric field. The Te ions are provided by the thin (∼5 nm) Te-rich layer formed at the bottom electrode interface.
- Published
- 2015
34. Nanosession: Atomic Layer Deposition
- Author
-
Cheol Seong Hwang, Woongkyu Lee, Jeong Hwan Han, Woojin Jeon, Yeon Woo Yoo, Changhee Ko, Julien Gatineau, B. Gouat, U. Weber, Peter K. Baumann, Michael Heuken, B. Lu, S. Hoffmann-Eifert, M. Reiners, N. Aslam, I. Kärkkänen, J. H. Kim, R. Waser, Taeyong Eom, Taehong Gwon, Si Jung Yoo, Moo-Sung Kim, Manchao Xiao, and Iain Buchanan
- Subjects
Atomic layer deposition ,Nanostructure ,Materials science ,Atomic layer epitaxy ,Nanotechnology ,Semiconductor device - Published
- 2013
35. Phase change memory cell using Ge2Sb2Te5 and softly broken-down TiO2 films for multilevel operation
- Author
-
Kyung-Min Kim, Taeyong Eom, Seol Choi, Cheol Seong Hwang, Sang Ho Rha, and Byung Joon Choi
- Subjects
Materials science ,Physics and Astronomy (miscellaneous) ,business.industry ,Stacking ,Nanotechnology ,Chemical vapor deposition ,Protein filament ,Phase-change memory ,Atomic layer deposition ,Semiconductor ,Thermoelectric effect ,Optoelectronics ,sense organs ,Thin film ,skin and connective tissue diseases ,business - Abstract
A phase change memory cell was fabricated by stacking plasma-enhanced cyclic chemical-vapor-deposited Ge2Sb2Te5 (GST) and atomic layer deposited TiO2 thin films. Different pairs of resistance states were obtained by controlling the current flow, which can be used to achieve higher memory density by multilevel operation. The multiresistance states of the stacked cell were explained by the resistance switching phenomena of TiO2 and the thermoelectric phase change properties of GST. The phase change characteristics of GST could be altered by controlling the degree of filament formation in the TiO2 layer, which eventually changed the phase change volume in the GST.
- Published
- 2010
36. Ge[sub 2]Sb[sub 2]Te[sub 5] Charge Trapping Nanoislands with High-k Blocking Oxides for Charge Trap Memory
- Author
-
Seol Choi, Jeong Hwan Kim, Cheol Seong Hwang, Minha Seo, Sang Ho Rha, Byung Joon Choi, Taeyong Eom, and Tae Joo Park
- Subjects
Materials science ,General Chemical Engineering ,Oxide ,Analytical chemistry ,Charge (physics) ,Trapping ,Chemical vapor deposition ,law.invention ,Capacitor ,chemistry.chemical_compound ,chemistry ,law ,Electrochemistry ,General Materials Science ,Electrical and Electronic Engineering ,Physical and Theoretical Chemistry ,Layer (electronics) ,Quantum tunnelling ,High-κ dielectric - Abstract
Charge trap memory capacitors using Ge 2 Sb 2 Te 5 (GST) nanoislands as charge storage media were fabricated. The GST nanoislands were prepared by plasma-enhanced cyclic chemical vapor deposition on a 6 nm thick tunneling SiO 2 layer. A 16 nm thick A1 2 O 3 or 40 nm thick HfO 2 film was used as the blocking oxide (BO). A shift in the flatband voltage in the capacitance-voltage test was achieved when the GST nanoislands were interposed between the SiO 2 and BOs, highlighting the feasibility of memory applications. The charges were trapped at the interface between the GST and BOs. Stable charge retention up to 10 4 s was observed.
- Published
- 2009
37. Switching Power Reduction in Phase Change Memory Cell Using CVD Ge[sub 2]Sb[sub 2]Te[sub 5] and Ultrathin TiO[sub 2] Films
- Author
-
Taeyong Eom, Hae Chan Park, Seol Choi, Cheol Seong Hwang, Seung Hwan Oh, Suk Kyoung Hong, Kyung-Woo Yi, Yoon-Jung Kim, Kyung-Min Kim, Yong Cheol Shin, Tae Sun Baek, and Byung Joon Choi
- Subjects
Phase-change memory ,Reduction (complexity) ,Materials science ,Renewable Energy, Sustainability and the Environment ,Switching power ,Materials Chemistry ,Electrochemistry ,Nanotechnology ,Condensed Matter Physics ,Surfaces, Coatings and Films ,Electronic, Optical and Magnetic Materials - Published
- 2009
38. (In,Sn)2O3∕TiO2∕Pt Schottky-type diode switch for the TiO2 resistive switching memory array
- Author
-
Kyung-Min Kim, Cheol Seong Hwang, Jaewon Song, Yong Cheol Shin, Gun Hwan Kim, Byung Joon Choi, Hyun Ju Lee, Taeyong Eom, and Seol Choi
- Subjects
Materials science ,Physics and Astronomy (miscellaneous) ,Stack (abstract data type) ,Rectification ,business.industry ,Optoelectronics ,Schottky diode ,Rectangular potential barrier ,business ,Backward diode ,Diode ,Step recovery diode ,Voltage - Abstract
A Schottky-type diode switch consisting of a Pt∕(In,Sn)2O3∕TiO2∕Pt stack was fabricated for applications to cross-bar type resistive-switching memory arrays. The high (0.55eV) and low potential barrier at the TiO2∕Pt and TiO2∕(In,Sn)2O3 junctions, respectively, constitute the rectifying properties of the stacked structure. The forward/reverse current ratio was as high as ∼1.6×104 at an applied voltage of ∼1V. When Pt∕TiO2∕Pt memory was connected to this diode in series, there was an insignificant interference on the memory function from the diode under the forward bias and virtually no resistive switching under a reverse bias.
- Published
- 2008
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