Effect of the Thermal Conductivity on Resistive Switching in GeTe and Ge2Sb2Te5 Nanowires

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• 作者：Sungjin Park ; Dambi Park ; Kwangsik Jeong ; Taeok Kim ; SeungJong Park ; Min Ahn ; Won Jun Yang ; Jeong Hwa Han ; Hong Sik Jeong ; Seong Gi Jeon ; Jae Yong Song ; Mann-Ho Cho
• 刊名：ACS Applied Materials & Interfaces
• 出版年：2015
• 出版时间：October 7, 2015
• 年：2015
• 卷：7
• 期：39
• 页码：21819-21827
• 全文大小：514K
• ISSN：1944-8252

文摘

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 (魏) of single crystalline GeTe and GST nanowires was decreased significantly to 1.44 Wm^鈥? K^鈥? for GeTe and 1.13 Wm^鈥? K^鈥? 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.