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Seedless Growth of Bismuth Nanowire Array via Vacuum Thermal Evaporation
Published on: December 21, 2015
Polymorphism of GeSbTe superlattice nanowires
Chan Su Jung1, Han Sung Kim, Hyung Soon Im
1Department of Chemistry, Korea University, Jochiwon 339-700, Korea.
Nano Letters
|January 18, 2013
Summary
Novel germanium-antimony-telluride (GeSbTe) nanowires (NWs) were synthesized for faster nonvolatile memory devices. Their unique superlattice structures and phase evolution offer promising applications in nanoscale electronics.
Area of Science:
- Materials Science
- Nanotechnology
- Solid State Physics
Background:
- Scaling down phase change materials to nanowire (NW) geometry is crucial for enhancing the switching speed of nonvolatile memory devices.
- Germanium-antimony-telluride (GeSbTe) alloys are key phase change materials used in memory applications.
- Controlling the phase and structure of GeSbTe at the nanoscale is essential for optimizing device performance.
Purpose of the Study:
- To synthesize novel composition-phase-tuned GeSbTe nanowires (NWs).
- To investigate the structural evolution and phase transitions in GeSbTe NWs with varying antimony content.
- To explore the potential of these NWs in nanoscale electric devices.
Main Methods:
- Chemical vapor transport (CVT) method for synthesizing GeSbTe NWs.
- Composition tuning by varying Sb content.
- Structural characterization using advanced microscopy techniques to identify superlattice structures.
- Current-voltage (I-V) measurements on individual NWs.
Main Results:
- Distinct rhombohedral-cubic-rhombohedral phase evolution observed with increasing Sb content.
- Identification of remarkable superlattice structures in various GeSbTe compositions (Ge(8)Sb(2)Te(11), Ge(3)Sb(2)Te(6), Ge(3)Sb(8)Te(6), Ge(2)Sb(7)Te(4)).
- Coexisting cubic-rhombohedral Ge(3)Sb(2)Te(6) NWs showed uniform 2.2 nm superlattice slabs.
- Rhombohedral Ge(3)Sb(8)Te(6) and Ge(2)Sb(7)Te(4) NWs exhibited novel structures with intercalated Sb(2) layers, forming 3.4 nm and 2.7 nm period slabs, respectively.
- Vacancy layers in Ge(8)Sb(2)Te(11) and Ge(3)Sb(2)Te(6) NWs were found to decrease electrical conductivity.
Conclusions:
- The study successfully synthesized GeSbTe NWs with tunable compositions and distinct phase evolutions.
- Novel superlattice structures, including intercalated layers, were identified, offering new avenues for material design.
- The findings highlight the potential of these engineered GeSbTe NWs for advanced nanoscale electronic devices, with conductivity influenced by vacancy layers.
