Structural and electrical properties of laser-ablated Ge2Sb2Te5 nanopa…

Phase-change Ge2Sb2Te5 (GST) nanoparticles have been in-situ synthesized by a pulsed laser ablation method. Temperature of heat treatment, pressure during ablation, and laser fluence are extensively explored to examine growth behavior of GST nanoparticles. Scanning and transmission electron microscopy are used to study microstructure and phase formation of the nanoparticles. Fourier transform analysis of electron micrographs exhibits the crystal structure of the Ge2Sb2Te5 phase. Energy dispersive x-ray analysis is performed to look into chemical composition of the GST nanoparticles. It is found that composition of nanoparticles varies with the temperature of heat treatment, pressure during deposition, fluence of the excimer laser. Current-voltage characteristics of the GST nanoparticles are examined in a metal-dot capacitor structure to investigate phase-dependent resistance effects. At a very low voltage a resistance-value transition from amorphous to crystalline phase is observed, indicating that the GST nanoparticles are promising to reduce down operating power of storage nodes or cells in nonvolatile memory devices.