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583 results on '"Ryu, Jae-Ha"'

167. Band-Bending of Ga-Polar GaN Interfaced with Al2O3through Ultraviolet/Ozone Treatment

Author

Kim, Kwangeun, Ryu, Jae Ha, Kim, Jisoo, Cho, Sang June, Liu, Dong, Park, Jeongpil, Lee, In-Kyu, Moody, Baxter, Zhou, Weidong, Albrecht, John, and Ma, Zhenqiang

Abstract

Understanding the band bending at the interface of GaN/dielectric under different surface treatment conditions is critically important for device design, device performance, and device reliability. The effects of ultraviolet/ozone (UV/O3) treatment of the GaN surface on the energy band bending of atomic-layer-deposition (ALD) Al2O3coated Ga-polar GaN were studied. The UV/O3treatment and post-ALD anneal can be used to effectively vary the band bending, the valence band offset, conduction band offset, and the interface dipole at the Al2O3/GaN interfaces. The UV/O3treatment increases the surface energy of the Ga-polar GaN, improves the uniformity of Al2O3deposition, and changes the amount of trapped charges in the ALD layer. The positively charged surface states formed by the UV/O3treatment-induced surface factors externally screen the effect of polarization charges in the GaN, in effect, determining the eventual energy band bending at the Al2O3/GaN interfaces. An optimal UV/O3treatment condition also exists for realizing the “best” interface conditions. The study of UV/O3treatment effect on the band alignments at the dielectric/III-nitride interfaces will be valuable for applications of transistors, light-emitting diodes, and photovoltaics.

Published
2017
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198. In vitro neuroprotective activity of sesquiterpenoids from the flower buds of Tussilago farfara.

Author

Lim, Hyo Jin, Dong, Guang-zhi, Lee, Hwa Jin, and Ryu, Jae-Ha

Subjects
TREATMENT of neurodegeneration, NEUROPROTECTIVE agents, SESQUITERPENES, TUSSILAGO farfara, HERBAL medicine, IN vitro studies
Abstract

We have isolated four sesquiterpenoids fromTussilago farfara, a traditional herbal medicine in Korea and China, and investigated the protective effects on LPS-induced neuronal cell death. Four sesquiterpenoids inhibited the production of nitric oxide, prostaglandin E2and tumor necrosis factor-α in LPS-treated BV-2 cells through the inhibition of NF-κB pathway. These sesquiterpenoids also inhibited reactive oxygen species (ROS) generation in LPS-treated BV-2 cells. Furthermore, they inhibited LPS-induced neuronal cell death in co-culture system through the inhibition of NF-κB pathway and scavenging of ROS. These results indicated that sesquiterpenoids fromTussilago farfaramay have beneficial therapeutic potential for the treatment of neurodegenerative diseases through inhibition of microglial activation. [ABSTRACT FROM AUTHOR]

Published
2015
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