title: Effect of the Thermal Conductivity on Resistive Switching in GeTe and Ge2Sb2Te5 Nanowires.
abstract: The thermal conduction characteristics of GeTe and Ge2Sb2Te5(GST) nanowires were investigated using an optical method to determine the local temperature by Raman spectroscopy. Since the localization of surface charge in a single-crystalline nanostructure can enhance charge-phonon scattering, the thermal conductivity value (κ) of single crystalline GeTe and GST nanowires was decreased significantly to 1.44 Wm(-1) K(-1) for GeTe and 1.13 Wm(-1) K(-1) for GST, compared to reported values for polycrystalline structures. The SET-to-RESET state in single-crystalline GeTe and GST nanowires are characteristic of a memory device. Unlike previous reports using GeTe and GST nanowires, the SET-to-RESET characteristics showed a bipolar switching shape and no unipolar switching. In addition, after multiple cycles of operation, a significant change in morphology and composition was observed without any structural phase transition, indicating that atoms migrate toward the cathode or anode, depending on their electronegativities. This change caused by a field effect indicates that the structural phase transition does not occur in the case of GeTe and GST nanowires with a significantly lowered thermal conductivity and stable crystalline structure. Finally, the formation of voids and hillocks as the result of the electromigration critically degrades device reliability.
authors.affiliation: Institute of Physics and Applied Physics, Yonsei University , Seoul, 120-749 Korea.
authors.forename: Sungjin
authors.initials: S
authors.lastname: Park
authors.affiliation: Institute of Physics and Applied Physics, Yonsei University , Seoul, 120-749 Korea.
authors.forename: Dambi
authors.initials: D
authors.lastname: Park
authors.affiliation: Institute of Physics and Applied Physics, Yonsei University , Seoul, 120-749 Korea.
authors.forename: Kwangsik
authors.initials: K
authors.lastname: Jeong
authors.affiliation: Institute of Physics and Applied Physics, Yonsei University , Seoul, 120-749 Korea.
authors.forename: Taeok
authors.initials: T
authors.lastname: Kim
authors.affiliation: Institute of Physics and Applied Physics, Yonsei University , Seoul, 120-749 Korea.
authors.forename: SeungJong
authors.initials: S
authors.lastname: Park
authors.affiliation: Institute of Physics and Applied Physics, Yonsei University , Seoul, 120-749 Korea.
authors.forename: Min
authors.initials: M
authors.lastname: Ahn
authors.affiliation: Institute of Physics and Applied Physics, Yonsei University , Seoul, 120-749 Korea.
authors.forename: Won Jun
authors.initials: WJ
authors.lastname: Yang
authors.affiliation: Institute of Physics and Applied Physics, Yonsei University , Seoul, 120-749 Korea.
authors.forename: Jeong Hwa
authors.initials: JH
authors.lastname: Han
authors.affiliation: School of Integrated Technology, Yonsei University , Incheon, 406-840 Korea.
authors.forename: Hong Sik
authors.initials: HS
authors.lastname: Jeong
authors.affiliation: Department of Materials Science and Engineering, Korea Advanced Institute of Science and Technology , Daejeon 305-701, Republic of Korea.
authors.forename: Seong Gi
authors.initials: SG
authors.lastname: Jeon
authors.affiliation: Korea Research Institute of Standards and Science , Daejeon 305-340, Republic of Korea.
authors.forename: Jae Yong
authors.initials: JY
authors.lastname: Song
authors.affiliation: Institute of Physics and Applied Physics, Yonsei University , Seoul, 120-749 Korea.
authors.forename: Mann-Ho
authors.initials: MH
authors.lastname: Cho
keywords: Ge2Sb2Te5; GeTe; bipolar switching property; phase-change memory; thermal conductivity