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Structural properties of solution-processed Hf0.5Zr0.5O2 thin films
이준영,아눕,이현준,곽정훈,조지영 한국물리학회 2017 Current Applied Physics Vol.17 No.5
Hf0.5Zr0.5O2 (HZO) thin films were deposited on Si substrates with and without TiN seed layers using a simple and cost-effective solution synthesis. The crystalline quality of the as-deposited HZO films were improved through a post deposition annealing process. Cross-sectional transmission electron microscope analyses of HZO/TiN/Si structure revealed a clear and clean interface formation between HZO and TiN layers. X-ray diffraction and Raman analyses confirm that, after the post annealing process, HZO films deposited on bare Si substrate crystallized in monoclinic phase while the HZO films deposited on TiN/Si substrates tend to crystallize in tetragonal or orthorhombic crystal structure. Varying crystal structure through controlling the post deposition annealing temperature is a promising technique to manipulate the electrical properties of solution processed HZO thin films.
조지영,아눕,박은영,이성수 대한금속·재료학회 2015 ELECTRONIC MATERIALS LETTERS Vol.11 No.4
The correlation between the structural, electrical, and luminescence behaviors of La-doped BaSnO3 (LBSO) epitaxial films was intensively studied. We found that Sn2+ defects and oxygen vacancies control the electrical properties of epitaxial LBSO films that are grown on (001)- oriented SrTiO3 substrates using pulsed laser deposition. Under optimized deposition condition, the films exhibit room temperature resistivity of 16 mΩ·cm, with a mobility of 1.62 cm2V−1s−1. To further reduce the resistivity, the films were vacuum-annealed at various temperatures in the range from 600°C to 900°C and the film annealed at 600°C exhibited the lowest room temperature resistivity of 5 mΩ·cm with the highest mobility of 3.09 cm2V−1s−1. The decrease of resistivity in the film vacuum-annealed at 600°C originates from the higher concentration of Sn2+ ions and oxygen vacancies, which was also confirmed from photoluminescence studies, in which emission peaks associated with Sn2+ defects were observed at 710 and 910 nm. Raman analysis revealed the presence of defect states related to octahedral tilting in vacuum-annealed LBSO films. Our studies show that the electrical properties of epitaxial films could be controlled by the Sn2+ defects generated with oxygen vacancies during the vacuum-annealing of the films.
임지석,아눕,손민균,강대준,정상윤,이상한,조지영 한국물리학회 2018 Current Applied Physics Vol.18 No.6
The insulator-metal transition (IMT) in vanadium dioxide (VO2) which occurs above room temperature (67 °C) is highly sensitive to atomic defects caused by oxygen stoichiometry. The strained growth and the degree of oxygen deficiency in VO2 epitaxial films result in lowering of transition temperature below room temperature as well as the broadening of transition parameters such as transition width and hysteresis width, which limit its application potential. Here we demonstrate the growth of highly oriented strain-relaxed VO2 thin films on (001)-oriented TiO2 substrates at various oxygen partial pressures, exhibiting the narrow transition and hysteresis width. The cross-sectional transmission electron microscopy and x-ray diffraction analyses of the films reveal the highly oriented growth of insulating monoclinic VO2. The IMT parameters associated with temperature-dependent phase transition vary with the oxygen partial pressure used during the deposition. The presence of multiple and mixed valence states of vanadium in the films was confirmed by Raman and XPS analyses. We have achieved a narrow transition width (2.3 °C) and hysteresis width (1.2 °C) through controlling the oxygen stoichiometry during the growth of VO2/TiO2 films.
Rethinking Postcapitalist Praxis
안잔 차크라바티,아눕 달 경상대학교 사회과학연구원 2022 마르크스주의 연구 Vol.19 No.2
This paper problematizes one crucial concept in Marxism: ‘third world’. It problematizes it through the return of the foreclosed language of class in the economy; which in turn enables us to find-found the ‘world of the third’ as the outside to the circuits of global capital. Such an outside opens the possibility of understanding Marxian postcapitalist praxis in/from the global South as a Moebius of resistance to capitalist and exploitative non-capitalist class processes and reconstruction of non-exploitative class processes – both within and outside the circuits of global capital. Postcapitalist politics of resistance-reconstruction inaugurates micro-processes of self-social-political transformation.
황승현,Sanjith Unithrattil,이현준,송재선,이혜정,아눕,이상한,조지영 한국물리학회 2019 Current Applied Physics Vol.19 No.8
Superlattice comprising of ferroelectric (FE) and non-ferroelectric (non-FE) material has been developed to induce a ferroelectric response in the non-ferroelectric layer. In this study, a superlattice thin film comprising of BiFeO3 (BFO) as FE oxide and La0.85Ce0.15MnO3 (LCMO) as semiconducting non-FE oxide is fabricated and investigated the FE and piezoelectric responses in LCMO. We observed the piezoelectric response of individual layers using time-resolved X-ray microdiffraction experiment under an external electric field. Piezoelectric response of individual layers was resolved by comparing it with the values obtained from kinematic diffraction calculation. Piezoelectric coefficient (d33) of LCMO monolayer is found to be approximately 27 pm/V, which is a similar value as that of the BFO layer.