One-dimensional Phase-Change Nanowires for Information Storage Application
X.H. Sun and B. Yu
NASA Ames Research Center, US
phase-change materials, nanowires, chalcogenide, phase-change random access memory
The electrically operated phase-change random access memory (PRAM) features faster write/read, improved endurance, and much simpler fabrication as compared with the traditional transistor-based nonvolatile semiconductor memories. Low-dimensional phase-change materials in nanoscale dimensions offer advantages over their bulk or thin-film counterpart in several aspects such as reduced programmable volume and reduced thermal energies in phase transition. These features contribute to low power operation, excellent scalability, and fast write/erase time. In this paper we reported a general bottom-up synthesis approach and systematic material analysis study of one-dimensional chalcogenide-based phase-change materials, germanium telluride (GeTe) and germanium antimony telluride (Ge2Sb2Te5) nanowires, which are targeted for nonvolatile resistive switching data storage. The phase-change nanowires have been synthesized via thermal evaporation method under vapor-liquid-solid (VLS) mechanism. The physical morphology, chemical composition, and crystal structure of the synthesized nanowires were investigated by scanning electron microscopy (SEM), energy dispersive X-ray spectroscopy (EDS), high-resolution transmission electron microscopy (HR-TEM) and X-ray photoemission spectroscopy (XPS). The as-synthesized nanowires are structurally uniform with single crystalline structures. The 1-D phase-change chalcogenide nanowires exhibit significantly reduced melting points, low activation energy and excellent morphology, making them promising nanomaterials for data storage devices with very low energy consumption and excellent scalability.
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Nanotech 2007 Conference Program Abstract