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