The Experts below are selected from a list of 231 Experts worldwide ranked by ideXlab platform

Ungyu Paik - One of the best experts on this subject based on the ideXlab platform.

  • Interpolymer complexes of poly(acrylic acid) and poly(ethylene glycol) for low dishing in STI CMP
    Applied Surface Science, 2015
    Co-Authors: Jihoon Seo, Jinok Moon, Sunho Moon, Ungyu Paik
    Abstract:

    Abstract Although poly(acrylic acid) (PAA) has been used as a Passivation Agent for high polish rate selectivity between SiO 2 and Si 3 N 4 in STI CMP, it causes severe dishing during the over-polishing step. Here, we fabricated interpolymer complexes of PAA and poly(ethylene glycol) (PEG) as Passivation Agent for low dishing as well as high selectivity. PAA and PEG form a cross-linked network structure through H-bonding, which is called an “interpolymer complex”. During the over-polishing step, the cross-linked network structure of the PAA-PEG interpolymer complex prevents abrasives from polishing SiO 2 in the trenches, resulting in a significant decrease in dishing. These results provide researchers with a new approach toward Passivation Agents to provide low dishing in STI CMP.

  • Constraints on removal of Si_3N_4 film with conformation-controlled poly(acrylic acid) in shallow-trench isolation chemical–mechanical planarization (STI CMP)
    Journal of Materials Research, 2008
    Co-Authors: Ye-hwan Kim, Ungyu Paik, Seung-mi Lee, Kee-june Lee, Jea-gun Park
    Abstract:

    The effect of changes in poly(acrylic acid) (PAA) conformation on removal of Si_3N_4 film was investigated. PAA was used as a Passivation Agent by adsorption on an Si_3N_4 film in shallow-trench isolation chemical–mechanical planarization (STI CMP). Adsorption behavior of PAA on the Si_3N_4 film and the conformation transition were determined by adsorption isotherms and force measurements using atomic force microscopy (AFM) as a function of ionic strength. AFM results revealed that, as ionic strength increases, the repulsive force between the negatively charged carboxylate groups along the backbone of PAA is reduced due to counterion screening and to the changes of PAA conformation from a stretched to a coiled configuration. At high ionic strength, the coiled conformation of PAA formed a dense Passivation layer on the Si_3N_4 film, which led to suppression of the removal rate of Si_3N_4 film from 72 to 61 Å/min in the STI CMP process.

Rukan Genc - One of the best experts on this subject based on the ideXlab platform.

  • Correction to: Differential Immunomodulatory Effect of Carbon Dots Influenced by the Type of Surface Passivation Agent
    Inflammation, 2020
    Co-Authors: Furkan Ayaz, Melis Ozge Alas, Rukan Genc
    Abstract:

    In the Published article, the article title shows “Differential Immunomodulatory Effect of Carbon Dots Influenced”. It should be “Differential Immunomodulatory Effect of Carbon Dots Influenced by the Type of Surface Passivation Agent”.

  • Differential Immunomodulatory Effect of Carbon Dots Influenced by the Type of Surface Passivation Agent
    Inflammation, 2019
    Co-Authors: Furkan Ayaz, Melis Ozge Alas, Rukan Genc
    Abstract:

    Carbon nanodots (CDs) are often synthesized from natural sources including honey, molasses, fruits, and foods, and plant extracts simply through caramelization. They have wide biological applications especially as drug delivery vehicles and bioimaging Agent due to their small size and biocompatibility. This article details the synthesis of carbon dots from carob and its derivatives by surface Passivation with polyethylene glycol (PEG), polyvinyl alcohol (PVA), and alginate (ALG). We investigated the immune response against CDs and evaluated the effect of surface Passivation Agents on their immunomodulatory functions. CD_PVA had strong anti-inflammatory activities, whereas CD_ALG were pro-inflammatory. CD_PEG had mild anti-inflammatory activities suggesting that these CDs can be used in the drug delivery studies as inert carriers. These results showed that depending on the type of activated groups dominated on the surface, CDs exerted differential effects on the inflammatory potential of the macrophages by changing the pro-inflammatory TNFα and IL6 production levels.

  • Fluorescent Carbon Dots from Nerium oleander: Effects of Physical Conditions and the Extract Types
    Journal of Fluorescence, 2019
    Co-Authors: Sinem Simsek, Melis Ozge Alas, Belma Özbek, Rukan Genc
    Abstract:

    In this original research, the synthesis of carbon nanodots (CDs) from two different solvent extracts of Nerium oleander by the thermal method was investigated under various physical conditions such as pH, reaction temperature, ionic strength, and surface Passivation Agent (polyethylene glycol, PEG) presence in the reaction media. The effects of extract types and physical conditions on CDs formation were characterized by UV-Visible spectrophotometry, fluorescence spectrophotometry, Fourier transform infrared spectroscopy and dynamic light scattering analysis. Fluorescent CDs were obtained from PEG included reaction media. Additionally, the enhanced fluorescence intensity correlated with ascending reaction temperature was reported. The hydrodynamic particle size of CDs in aqueous solution was determined between ~1 and 235 nm with negative surface potential in the range of −6 mV and −28 mV. Moreover, CDs synthesized from aqueous extract mostly resulted in smaller size than that of ethanol extract based ones. The impact of surface Passivation with PEG on the fluorescence feature of CDs was verified. For the relevant extracts of Oleander, CDs synthesized from PEG included formulations at pH 5 and NaCl free reaction media found as better alternatives than CDs synthesized under other conditions taking account their effect on fluorescence feature, hydrodynamic size and etc. Graphical Abstract

  • Evaluation of the physical properties of fluorescent carbon nanodots synthesized using Nerium oleander extracts by microwave-assisted synthesis methods
    Journal of Materials Research and Technology, 2019
    Co-Authors: Sinem Simsek, Melis Ozge Alas, Belma Özbek, Rukan Genc
    Abstract:

    Abstract Rapid and one-step green synthesis of carbon nanodots (CDs) from Nerium oleander leaves was accomplished via domestic microwave oven and microwave-assisted hydrothermal synthesizer under various physical conditions. Effects of the synthesizer system, extract type depending on the solvents used in plant extraction, and synthesis conditions; such as reaction time, reaction temperature, surface Passivation Agent inclusion into the reaction medium, on the physicochemical properties and optical feature of CDs were investigated. The impacts of relevant conditions on CDs feature were determined clearly via UV–visible spectrophotometry, fluorescence spectrophotometry, dynamic light scattering analysis, and Fourier transform infrared spectroscopy. According to the results, while the most effective parameter on the fluorescence feature of CDs was determined as the presence of surface Passivation Agent (polyethylene glycol, PEG), the alteration in the fluorescence intensity depending on the reaction time and the reaction temperature was also observed. It was reported that the synthesis system and PEG existence in the reaction medium were more effective than the other inspected parameters on the hydrodynamic particle size, in general. Under optimum conditions, nanoparticles with a hydrodynamic size of less than 5 nm were obtained. The surface zeta potential charges of all particles were found as negative. While the extract type was significantly effective on the surface zeta potential of CDs synthesized by domestic microwave oven, the reaction temperature was found to be significant for the ones synthesized via microwave-assisted hydrothermal synthesis.

Shengping Ruan - One of the best experts on this subject based on the ideXlab platform.

  • Passivation Agent with dipole moment for surface modification towards efficient and stable perovskite solar cells
    Journal of Energy Chemistry, 2021
    Co-Authors: Ge Wang, Chen Wang, Yajun Gao, Shanpeng Wen, Roderick C I Mackenzie, Liuxing Guo, Wei Dong, Shengping Ruan
    Abstract:

    Abstract Recently, there has been renewed interest in interface engineering as a means to further push the performance of perovskite solar cells closer to the Schockly-Queisser limit. Herein, for the first time we employ a multi-functional 4-chlorobenzoic acid to produce a self-assembled monolayer on a perovskite surface. With this interlayer we observe Passivation of perovskite surface defects and a significant suppression of non-radiative charge recombination. Furthermore, at the surface of the interlayer we observe, charge dipoles which tune the energy level alignment, enabling a larger energetic driving force for hole extraction. The perovskite surface becomes more hydrophilic due to the presence of the interlayer. Consequently, we observe an improvement in open-circuit voltage from 1.08 to 1.16 V, a power conversion efficiency improvement from 18% to 21% and an improved stability under ambient conditions. Our work highlights the potential of SAMs to engineer the photo-electronic properties and stability of perovskite interfaces to achieve high-performance light harvesting devices.

Jea-gun Park - One of the best experts on this subject based on the ideXlab platform.

  • Constraints on removal of Si_3N_4 film with conformation-controlled poly(acrylic acid) in shallow-trench isolation chemical–mechanical planarization (STI CMP)
    Journal of Materials Research, 2008
    Co-Authors: Ye-hwan Kim, Ungyu Paik, Seung-mi Lee, Kee-june Lee, Jea-gun Park
    Abstract:

    The effect of changes in poly(acrylic acid) (PAA) conformation on removal of Si_3N_4 film was investigated. PAA was used as a Passivation Agent by adsorption on an Si_3N_4 film in shallow-trench isolation chemical–mechanical planarization (STI CMP). Adsorption behavior of PAA on the Si_3N_4 film and the conformation transition were determined by adsorption isotherms and force measurements using atomic force microscopy (AFM) as a function of ionic strength. AFM results revealed that, as ionic strength increases, the repulsive force between the negatively charged carboxylate groups along the backbone of PAA is reduced due to counterion screening and to the changes of PAA conformation from a stretched to a coiled configuration. At high ionic strength, the coiled conformation of PAA formed a dense Passivation layer on the Si_3N_4 film, which led to suppression of the removal rate of Si_3N_4 film from 72 to 61 Å/min in the STI CMP process.

Li Bao - One of the best experts on this subject based on the ideXlab platform.

  • The influence of passivating Agent on soil pollution
    MethodsX, 2021
    Co-Authors: Kai Wang, Naiming Zhang, Fuming Tan, He Jie, Li Bao
    Abstract:

    Abstract In this paper, different materials such as phosphogypsum, raw coal and iron slag, which are more concerned in chemical Passivation, are selected to mix an efficient and cheap Passivation Agent to repair Cd and As compound contaminated soil and realize the reuse of solid waste resources. The heavy metals Cd and As are not only toxic to the soil-plant system, but also migrate to animals and humans through the food chain, destroying normal physiological functions, and causing great harm to the human body. The essential functions of the newly developed heavy metal passivator are as follows: • Changed the microscopic morphology of the soil • Greatly reduce the bioavailability of Cd and As in the soil