Polymorphism of GeSbTe Superlattice Nanowires

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• 作者：Chan Su Jung ; Han Sung Kim ; Hyung Soon Im ; Young Seok Seo ; Kidong Park ; Seung Hyuk Back ; Yong Jae Cho ; Chang Hyun Kim ; Jeunghee Park ; Jae-Pyoung Ahn
• 刊名：Nano Letters
• 出版年：2013
• 出版时间：February 13, 2013
• 年：2013
• 卷：13
• 期：2
• 页码：543-549
• 全文大小：531K
• 年卷期：v.13,no.2(February 13, 2013)
• ISSN：1530-6992

文摘

Scaling-down of phase change materials to a nanowire (NW) geometry is critical to a fast switching speed of nonvolatile memory devices. Herein, we report novel composition-phase-tuned GeSbTe NWs, synthesized by a chemical vapor transport method, which guarantees promising applications in the field of nanoscale electric devices. As the Sb content increased, they showed a distinctive rhombohedral鈥揷ubic鈥搑hombohedral phase evolution. Remarkable superlattice structures were identified for the Ge₈Sb₂Te₁₁, Ge₃Sb₂Te₆, Ge₃Sb₈Te₆, and Ge₂Sb₇Te₄ NWs. The coexisting cubic鈥搑hombohedral phase Ge₃Sb₂Te₆ NWs exhibited an exclusively uniform superlattice structure consisting of 2.2 nm period slabs. The rhombohedral phase Ge₃Sb₈Te₆ and Ge₂Sb₇Te₄ NWs adopted an innovative structure; 3Sb₂ layers intercalated the Ge₃Sb₂Te₆ and Ge₂Sb₁Te₄ domains, respectively, producing 3.4 and 2.7 nm period slabs. The current鈥搗oltage measurement of the individual NW revealed that the vacancy layers of Ge₈Sb₂Te₁₁ and Ge₃Sb₂Te₆ decreased the electrical conductivity.

Keywords:

GeSbTe; nanowires; polymorphism; superlattices; phase change; cubic鈭抮hombohedral transition