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101.
A new design concept for diffusion barriers in high‐density memory capacitors is suggested, and both RuTiN (RTN) and RuTiO (RTO) films are proposed as sacrificial oxygen diffusion barriers. The newly developed RTN and RTO barriers show a much lower sheet resistance than various other barriers, including binary and ternary nitrides (reported by others), up to 800 °C, without a large increase in the resistance. For both the Pt/RTN/TiSix/n++poly‐plug/n+ channel layer/Si and the Pt/RTO/RTN/TiSix/n++poly‐plug/n+ channel layer/Si contact structures, contact resistance—the most important electrical parameter for the diffusion barrier in the bottom electrode structure of capacitors—was found to be as low as 5 kohm, even after annealing up to 750 °C. When the RTN film was inserted as a glue layer between the bottom Pt electrode layer and the TiN barrier film in the chemical vapor deposited (Ba,Sr)TiO3 (CVD–BST) simple stack‐type structure, the RTN glue layer was observed to be thermally stable to temperatures 150 °C higher than that to which the TiN glue layer is stable. Moreover, the capacitance of the physical vapor deposited (PVD)–BST simple stack‐type structure adopted TiN glue layer initially degraded after annealing at 500 °C, and, thereafter, completely failed. In the case of the RTN and RTO/RTN glue layers, however, the capacitance continuously increased up to 550 °C. Thus, the new RTN and RTO films, which act as diffusion barriers to oxygen, are very promising materials for achieving high‐density capacitors. 相似文献
102.
Nanoscale patterning of colloidal quantum dots on transparent and metallic planar surfaces 总被引:1,自引:0,他引:1
Y Park YG Roh UJ Kim DY Chung H Suh J Kim S Cheon J Lee TH Kim KS Cho CW Lee 《Nanotechnology》2012,23(35):355302
The patterning of colloidal quantum dots with nanometer resolution is essential for their application in photonics and plasmonics. Several patterning approaches, such as the use of polymer composites, molecular lock-and-key methods, inkjet printing and microcontact printing of quantum dots have been recently developed. Herein, we present a simple method of patterning colloidal quantum dots for photonic nanostructures such as straight lines, rings and dot patterns either on transparent or metallic substrates. Sub-10?nm width of the patterned line could be achieved with a well-defined sidewall profile. Using this method, we demonstrate a surface plasmon launcher from a quantum dot cluster in the visible spectrum. 相似文献
103.
Lee JK Lee JW Bae JH Park J Chung SW Roh JS Hong SJ Lee JH 《Journal of nanoscience and nanotechnology》2012,12(7):5392-5396
As dimensions of resistive random access memories (RRAMs) devices continue to shrink, the low-frequency noise of nanoscale devices has become increasingly important in evaluating the device reliability. Thus, we investigated random telegraph noise (RTN) caused by capture and emission of an electron at traps. We physically analyzed capture and emission processes through systematic measurements of amorphous TiOx (alpha-TiOx)-based bipolar RRAMs. RTNs were observed during high-resistance state (HRS) in most devices. However, discrete switching behavior was scarcely observed in low-resistance state (LRS) as most of traps in the alpha-TiOx were filled with mobile ions such as O2- in LRS. The capture and emission processes of an electron at traps are largely divided into two groups: (1) both capture and emission processes are mainly affected by electric field; and (2) one of the capture and emission processes is only influenced by the thermal process. This paper provides fundamental physics required to understand the mechanism of RTNs in alpha-TiOx-based bipolar RRAMs. 相似文献
104.
Control of particle size and shape of precursors for ceria using ammonium carbonate as a precipitant
Spherical nanocrystalline precursors of ceria (CeO2) and CeO2 powder with different size distributions were prepared by a reflux method using cerium nitrate hexahydrate (CN) as the cerium source and ammonium carbonate (AC) as the precipitant. The crystalline phases of the synthesized CeO2 precursors were identified as orthorhombic Ce2O(CO3)2·H2O and hexagonal CeCO3OH. The particle size and shape could be easily controlled by the CN concentration and the ratio of [AC]/[CN]. The CeO2 precursors were calcined at 400-700 °C to obtain CeO2. The particle size distribution and morphology of the synthesized CeO2 powders were unaffected by the calcination. The specific surface area of the CeO2 powders was increased by the release of CO2 and H2O during the calcination. The calcination temperature is an important factor for the preparation of CeO2 powder with a high surface area. 相似文献
105.
Cold Oxygen Plasma Treatments for the Improvement of the Physicochemical and Biodegradable Properties of Polylactic Acid Films for Food Packaging
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Ah Young Song Yoon Ah Oh Si Hyeon Roh Ji Hyeon Kim Sea C. Min 《Journal of food science》2016,81(1):E86-E96
The effects of cold plasma (CP) treatment on the physicochemical and biodegradable properties of polylactic acid (PLA) films were studied. The PLA films were exposed to CP for 40 min at 900 W and 667 Pa using oxygen as the plasma‐forming gas. The tensile, optical, and dynamic mechanical thermal properties, surface morphology, printability, water contact angle, chemical structure, weight change, and biodegradability properties of the films were evaluated during storage for up to 56 d. The tensile and optical properties of the PLA films were not significantly affected by CP treatment (CPT; P > 0.05). The surface roughness and water contact angle of PLA films increased by CPT and further increased during storage for 56 d. The printability of the PLA films increased following CPT and remained stable throughout the storage period. CP‐induced hydrophilicity was also sustained during the storage period. The PLA films lost 1.9% of their weight after CPT, but recovered 99.5% of this loss after 14 d in storage. Photodegradation, thermal, and microbial biodegradable properties of the films were significantly improved by CPT (P < 0.05). Accelerated biodegradation of CP‐treated PLA sachets with and without cheese was observed in compost. These results demonstrate the potential of CPT for modifying the stiffness, water contact angle, and chemical structure of PLA films and improving the printability and biodegradability of the films for food packaging. 相似文献
106.
107.
Seungkook Roh 《Journal of Nuclear Science and Technology》2017,54(8):830-836
The perceived benefit and risk of nuclear power generation have received considerable attention as determinants of the public's nuclear power acceptance. However, the contingency of the relative importance of these benefit and risk has been less explored. Using Korea as an example, this study explores the possibility that the relative importance of perceived benefit and risk on nuclear power acceptance depends on acceptance levels. Our results from latent class analysis and multinomial probit show that, in determining whether an individual shows a moderate level of nuclear power acceptance rather than a low level, perceived risk plays a dominant role compared to perceived benefit; however, regarding whether he/she shows a high level of nuclear power acceptance rather than a moderate level, this relative importance is reversed. These results carry practical implications for risk governance of nuclear power, particularly with regard to communication with the public. 相似文献
108.
Flow instability in LRE (liquid rocket engine) occurs due to various reasons such as flow interactions with valve, orifice
and venturi, etc. The inception of cavitation, especially in the propellant feeding system, is the primary cause of mass and
pressure oscillations because of the cyclic formation and depletion of cavitation. Meanwhile, the main propellant in a liquid
rocket engine is the cryogenic fluid, which properties are very sensitive to temperature variation. And the change of propellant
properties to temperature variation by thermodynamic effect needs to be properly taken into account in the flow analysis in
order to understand basic mechanisms for cryogenic cavitation. The present study focuses on the formation of cryogenic cavitation
by using the IDM model suggested by Shyy and coworkers. The flow instability was also numerically investigated in the downstream
of orifice with a developed numerical code. Calculation results show that cryogenic cavitation can be a primary source of
flow instability, leading to mass fluctuations accompanied by pressure oscillations. The prediction of cavitation in cryogenic
fluid is of vital importance in designing a feeding system of an LRE.
This paper was recommended for publication in revised form by Associate Editor Jun Sang Park
Changjin Lee received his B.S. and M.S. degrees in Aeronautical Engineering from Seoul National University in 1983 and 1985. He then went
on to receive his Ph.D. degree from University of Illinois at Urbana- Champaign in 1992. Dr. Lee is currently a Professor
at the department of Aerospace Engineering at Konkuk University in SEOUL, Korea. His research interests are in the area of
combustion instabilities of hybrid, liquid rocket and jet propulsions.
Tae-Seong Roh received his B.S. and M.S. degrees in Aeronautical Engineering from Seoul National University in 1984 and 1986. He then went
on to receive his Ph.D. degree from Pennsylvania State University in 1995. Dr. Roh is currently a Professor at the department
of Aerospace Engineering at Inha University in Incheon, Korea. His research interests are in the area of combustion instabilities,
rocket and jet propulsions, interior ballistics, and gas turbine engine defect diagnostics. 相似文献
109.
The influence of formaldehyde/urea (F/U) mole ratio and melamine content on the hydrolytic stability
of urea-melamine-formaldehyde (UMF) resin was investigated. The hydrolytic stability of cured UMF resin
was determined by measuring the mass loss and the liberated formaldehyde concentration after acid hydrolysis.
A higher F/U mole ratio and greater melamine content of UMF resins resulted in lower hydrolytic stability.
These results indicated that higher F/U mole ratio and greater melamine content resulted in more branched
network structure, which subsequently increases the susceptibility of cured UMF resin toward acid hydrolysis. 相似文献
110.
Material transportation scheduling problems concerning scheduling optimisation have been extensively investigated by researchers in such fields as industrial engineering and management science. Various algorithms have been proposed to solve such problems. However, the majority of these algorithms cannot be applied to a block transportation problem when a shipyard that uses a transporter, a large vehicle employed for moving weight, is considered. In this study, a hybrid optimisation algorithm is proposed for solving a block transportation problem when multiple transporters are used. With regards to the transporters, a minimisation of the travel distance without loading of and interference between the transporters is considered. A block transportation scheduling system is then developed based on the proposed algorithm. The developed system is applied to an actual block transportation scheduling problem of a shipyard. From the attained results, we demonstrate that the proposed algorithm has the ability to effectively solve the block transportation scheduling problems of a shipyard. 相似文献