title: Polymorphism of GeSbTe superlattice nanowires.
abstract: 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-cubic-rhombohedral phase evolution. Remarkable superlattice structures were identified for the Ge(8)Sb(2)Te(11), Ge(3)Sb(2)Te(6), Ge(3)Sb(8)Te(6), and Ge(2)Sb(7)Te(4) NWs. The coexisting cubic-rhombohedral phase Ge(3)Sb(2)Te(6) NWs exhibited an exclusively uniform superlattice structure consisting of 2.2 nm period slabs. The rhombohedral phase Ge(3)Sb(8)Te(6) and Ge(2)Sb(7)Te(4) NWs adopted an innovative structure; 3Sb(2) layers intercalated the Ge(3)Sb(2)Te(6) and Ge(2)Sb(1)Te(4) domains, respectively, producing 3.4 and 2.7 nm period slabs. The current-voltage measurement of the individual NW revealed that the vacancy layers of Ge(8)Sb(2)Te(11) and Ge(3)Sb(2)Te(6) decreased the electrical conductivity.
authors: Department of Chemistry, Korea University, Jochiwon 339-700, Korea.
authors: Chan Su
authors: CS
authors: Jung
authors: Han Sung
authors: HS
authors: Kim
authors: Hyung Soon
authors: HS
authors: Im
authors: Young Seok
authors: YS
authors: Seo
authors: Kidong
authors: K
authors: Park
authors: Seung Hyuk
authors: SH
authors: Back
authors: Yong Jae
authors: YJ
authors: Cho
authors: Chang Hyun
authors: CH
authors: Kim
authors: Jeunghee
authors: J
authors: Park
authors: Jae-Pyoung
authors: JP
authors: Ahn