Search

Your search keyword '"Khang, YoonHo"' showing total 27 results
Start Over Author "Khang, YoonHo"
27 results on '"Khang, YoonHo"'

4. Electronic structure of (Ge2Sb2Te5)1-x(In3SbTe2)x investigated by x-ray photoelectron spectroscopy.

Author

Benayad, Anass, Kang, YounSeon, Shin, Hyun-Joon, Kim, Kihong, Suh, Dong-Seok, Kim, KiJoon, Kim, CheolKyu, Lee, Tae-Yon, Noh, Jin-Seo, Lee, JaeCheol, and Khang, YoonHo

Subjects
X-ray photoelectron spectroscopy, ELECTRONIC structure, BINDING energy, INDIUM, VALENCE fluctuations, TRANSITION temperature
Abstract

We have investigated the core levels and the valence band of (Ge2Sb2Te5)1-x(In3Sb1Te2)x quaternary phase system (IGST) by means of x-ray photoelectron spectroscopy. A systematic shift of Sb 3d and Ge 2p core-level peaks toward lower binding energies side was observed with increasing indium amount, whereas the In 3d and Te 3d core peaks showed less change. The Sb 3d and Ge 2p core-level shift is attributed to an increase in the electronic charge of p-electrons dependent of indium amount. The valence band spectra show a distinct change in the sp configuration with indium concentration change. The change in the local bonding as the indium amount increase has a profound impact on both local atomic arrangement and amorphous-to-crystalline transformation temperature. The difference in the photoemission spectra have been discussed according to a simple structural model suggesting that the Na site in IGST can be occupied by Te, Sb, In, and vacancy, whereas in GST it is occupied only by Te. [ABSTRACT FROM AUTHOR]

Published
2009
Full Text
View/download PDF

5. Crystalline and amorphous structures of Ge–Sb–Te nanoparticles.

Author

Park, Gyeong-Su, Kwon, Ji-Hwan, Kim, Miyoung, Yoon, H. R., Jo, W., Kim, T. K., Zuo, Jian-Min, and Khang, Yoonho

Subjects
NANOPARTICLES, NANOCRYSTALS, THIN films, DISTRIBUTION (Probability theory), ELECTRON diffraction, LASER ablation
Abstract

We report effects of thermal annealing on the structures of Ge–Sb–Te (GST) nanoparticles synthesized by pulsed laser ablation deposition. The average diameter of the GST nanoparticles is an order of 10 nm. The as-prepared sample contains nanocrystals surrounded by an amorphous phase. Further crystallization occurs during annealing. The structures of the nanocrystals and amorphous phase were studied by electron diffraction and radial distribution function analyses. The results show that the nanoparticles annealed at 100 °C are crystalline, consisting of a mixture of face centered cubic (fcc) and hexagonal Ge2Sb2Te5 (dominant). In comparison, the nanoparticles annealed at 200 °C are mostly fcc. The surrounding amorphous phase has similar atomic arrangements to the previously reported amorphous GST thin films. [ABSTRACT FROM AUTHOR]

Published
2007
Full Text
View/download PDF

9. Electric-Field-Induced Mass Movement of Ge[sub 2]Sb[sub 2]Te[sub 5] in Bottleneck Geometry Line Structures

Author

Nam, Sung-Wook, primary, Lee, Dongbok, additional, Kwon, Min-Ho, additional, Kang, Dongmin, additional, Kim, Cheolkyu, additional, Lee, Tae-Yon, additional, Heo, Sung, additional, Park, Young-Wook, additional, Lim, Kipil, additional, Lee, Hyo-Sung, additional, Wi, Jung-Sub, additional, Yi, Kyung-Woo, additional, Khang, Yoonho, additional, and Kim, Ki-Bum, additional

Published
2009
Full Text
View/download PDF

15. Valence band structures of the phase change material Ge2Sb2Te5

Author

Lee, Dohyun, primary, Lee, Sang Sun, additional, Kim, Wondong, additional, Hwang, Chanyong, additional, Hossain, M. B., additional, Hung, Ngyuen Le, additional, Kim, Hyojin, additional, Kim, C. G., additional, Lee, Hangil, additional, Hwang, Han Na, additional, Hwang, Chan-Cuk, additional, Lee, Tae-Yon, additional, Kang, Younseon, additional, Kim, Cheolkyu, additional, Suh, Dong-Seok, additional, Kim, Kijoon H. P., additional, and Khang, Yoonho, additional

Published
2007
Full Text
View/download PDF

17. Experimental Setup forin SituInvestigation of Phase Changing Behavior in Phase-Change Random-Access Memory Medium by Microfocusing Nanosecond-Time-Resolved Ellipsometry

Author

Kim, Younhwa, primary, Kim, Sang Jun, additional, Kim, Sang Youl, additional, An, Sung Hyuck, additional, Suh, Dong-Seok, additional, Noh, Jin-Seo, additional, Lee, Sang Mock, additional, Kim, Kijoon H. P., additional, Shin, Woong-Chul, additional, and Khang, Yoonho, additional

Published
2006
Full Text
View/download PDF

23. Electric-Field-Induced Mass Movement of Ge2Sb2Te5 in Bottleneck Geometry Line Structures

Author

Nam, Wook, Lee, Dongbok, Kwon, Ho, Kang, Dongmin, Kim, Cheolkyu, Lee, Yon, Heo, Sung, Park, Wook, Lim, Kipil, Lee, Sung, Wi, Sub, Yi, Woo, Khang, Yoonho, and Kim, Bum

Abstract

We report an electric-field-induced directional mass movement of in bottleneck geometry. Under high-electric-stress circumstances , a mass of tends to move toward the cathode ([?]) by the remaining mass depletion at the anode (+). The high electric stress induces an asymmetric compositional separation such that Sb is distributed toward the cathode ([?]) whereas Te is distributed toward the anode (+). Ionicity in at high temperature and high electric stress can be one of the origins of the asymmetric behavior. The electric-field-induced mass movement may provide insight on the device reliability of phase-change random access memory.

Published
2009

24. Valence band structures of the phase change material Ge2Sb2Te5.

Author

Lee, Dohyun, Lee, Sang Sun, Kim, Wondong, Hwang, Chanyong, Hossain, M. B., Hung, Ngyuen Le, Kim, Hyojin, Kim, C. G., Lee, Hangil, Hwang, Han Na, Hwang, Chan-Cuk, Lee, Tae-Yon, Kang, Younseon, Kim, Cheolkyu, Suh, Dong-Seok, Kim, Kijoon H. P., and Khang, Yoonho

Subjects
CONDUCTION electrons, GERMANIUM compounds, PHOTOEMISSION, ULTRAVIOLET spectra, CRYSTALLIZATION
Abstract

We report the experimental evidence of significant change of the valence band structure during crystallization of Ge2Sb2Te5 (GST). Amorphous GST, prepared by sputter deposition at room temperature (RT), transforms successively into face-centered-cubic (fcc) and a hexagonal-close-packed (hcp) structures at around 150 and 300 °C, respectively, during a stepwise temperature increase from RT to 350 °C. During temperature increase, ultraviolet photoemission spectra were in vacuo obtained using synchrotron radiation. The measurement of the amorphous and fcc GST shows that the difference between the maximum valence band edge and the Fermi level reduces by 0.35 eV during crystallization. For the fcc to hcp phase transformation, no band gap reduction was observed. [ABSTRACT FROM AUTHOR]

Published
2007
Full Text
View/download PDF

25. Nonvolatile switching characteristics of laser-ablated Ge2Sb2Te5 nanoparticles for phase-change memory applications.

Author

Suh, Dong-Seok, Lee, Eunhye, Kim, Kijoon H. P., Noh, Jin-Seo, Shin, Woong-Chul, Kang, Youn-Seon, Kim, Cheolkyu, Khang, Yoonho, Yoon, H. R., and Jo, W.

Subjects
ELECTRICITY, NANOPARTICLES, LASER ablation, THIN films, SCALING laws (Statistical physics), PROBABILITY theory, RESEARCH
Abstract

Electrical characteristics of Ge2Sb2Te5 (GST) nanoparticles have been examined for a phase-change memory applications. The GST nanoparticles were generated by in situ pulsed laser ablation and their crystal structure formation was confirmed [H. R. Yoon et al., J. Non-Cryst. Solids 351, 3430 (2005)]. A stacked structure of the GST nanoparticles with 10 nm of average diameter shows reversible nonvolatile switching characteristics between a high resistance state and a low resistance state as in the phase-change memory consisting of bulk GST thin film. Experimental results indicate that it is highly probable to test scaling issues of the phase-change memory with well-defined GST nanoparticles. [ABSTRACT FROM AUTHOR]

Published
2007
Full Text
View/download PDF

26. Electric-Field-Induced Mass Movement of Ge2Sb2Te5in Bottleneck Geometry Line Structures

Author

Nam, Sung-Wook, Lee, Dongbok, Kwon, Min-Ho, Kang, Dongmin, Kim, Cheolkyu, Lee, Tae-Yon, Heo, Sung, Park, Young-Wook, Lim, Kipil, Lee, Hyo-Sung, Wi, Jung-Sub, Yi, Kyung-Woo, Khang, Yoonho, and Kim, Ki-Bum

Abstract

We report an electric-field-induced directional mass movement of Ge2Sb2Te5in bottleneck geometry. Under high-electric-stress circumstances (106Acm−2), a mass of Ge2Sb2Te5tends to move toward the cathode (−) by the remaining mass depletion at the anode (+). The high electric stress induces an asymmetric compositional separation such that Sb is distributed toward the cathode (−) whereas Te is distributed toward the anode (+). Ionicity in Ge2Sb2Te5at high temperature and high electric stress can be one of the origins of the asymmetric behavior. The electric-field-induced mass movement may provide insight on the device reliability of phase-change random access memory.

Published
2009
Full Text
View/download PDF

27. Valence band structures of the phase change material Ge2Sb2Te5.

Author

Lee, Dohyun, Lee, Sang Sun, Kim, Wondong, Hwang, Chanyong, Hossain, M. B., Hung, Ngyuen Le, Kim, Hyojin, Kim, C. G., Lee, Hangil, Hwang, Han Na, Hwang, Chan-Cuk, Lee, Tae-Yon, Kang, Younseon, Kim, Cheolkyu, Suh, Dong-Seok, Kim, Kijoon H. P., and Khang, Yoonho

Subjects
*CONDUCTION electrons, *GERMANIUM compounds, *PHOTOEMISSION, *ULTRAVIOLET spectra, *CRYSTALLIZATION
Abstract

We report the experimental evidence of significant change of the valence band structure during crystallization of Ge2Sb2Te5 (GST). Amorphous GST, prepared by sputter deposition at room temperature (RT), transforms successively into face-centered-cubic (fcc) and a hexagonal-close-packed (hcp) structures at around 150 and 300 °C, respectively, during a stepwise temperature increase from RT to 350 °C. During temperature increase, ultraviolet photoemission spectra were in vacuo obtained using synchrotron radiation. The measurement of the amorphous and fcc GST shows that the difference between the maximum valence band edge and the Fermi level reduces by 0.35 eV during crystallization. For the fcc to hcp phase transformation, no band gap reduction was observed. [ABSTRACT FROM AUTHOR]

Published
2007
Full Text
View/download PDF

Catalog

Books, media, physical & digital resources
See catalog results