(A) transmission electron microscopy study on the crystallization of $Ge_2Sb_2Te_5$ thin films deposited by sputtering method = 스퍼터링 방법으로 증착된 $Ge_2Sb_2Te_5$ 박막의 결정화에 관한 투과전자현미경 연구

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A non-volatile memory device using $Ge_2Sb_2Te_5$ thin films are one of the most promising candidates for high-speed mass storage in computer systems. Especially, in the viewpoint of the phase-change random access memory, the research on $Ge_2Sb_2Te_5$, phase-change materials, is very important. Up to date, microscopic analyses for identifying the electrical characteristics of $Ge_2Sb_2Te_5$ have been mainly carried out. Even though there were many researches on the microstructure of $Ge_2Sb_2Te_5$, a high-resolution transmission electron microscopy study on an atomic level was little investigated. In other words, the fundamental studies of the crystal structure and atomic arrangement of the $Ge_2Sb_2Te_5$ on an atomic level leave much to be desired. Therefore, atomic arrangement and phase transition mechanism of the $Ge_2Sb_2Te_5$ should clearly be understood in order to overcome the technical barrier of non-volatile memory device. In this thesis, a transmission electron microscopy study was performed to investigate the fundamental theory on the atomic arrangement and phase transition mechanism. The $Ge_2Sb_2Te_5$ thin films deposited by a sputtering method on a %SiO_2/Si$ substrate were annealed and subjected to transmission electron microscopy in order to investigate the crystallization and growth of the metastable $Ge_2Sb_2Te_5$. The metastable $Ge_2Sb_2Te_5$was initially crystallized with 10-nm-sized grains and its sheet resistance was still as high as in the amorphous state. However, resistivity value was abruptly decreased at the grain growth stage after the crystallization. On the basis of the results of the microstructural and electrical characteristics from the annealing time and temperature variation, it can be stated that the electrical properties of the $Ge_2Sb_2Te_5$ film are directly related to the grain growth and thus, the grain size. The crystal structure and atomic arrangement of the metastable $Ge_2Sb_2Te_5$ were studied by a high-resol...
Advisors
Lee, Jeong-Yongresearcher이정용researcher
Description
한국과학기술원 : 신소재공학과,
Publisher
한국과학기술원
Issue Date
2006
Identifier
258126/325007  / 020025835
Language
eng
Description

학위논문(박사) - 한국과학기술원 : 신소재공학과, 2006.2, [ xvii, 171 p. ]

Keywords

Transmission electron microscopy; 투과전자현미경

URI
http://hdl.handle.net/10203/49643
Link
http://library.kaist.ac.kr/search/detail/view.do?bibCtrlNo=258126&flag=dissertation
Appears in Collection
MS-Theses_Ph.D.(박사논문)
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