In-situ TEM observation on nanostructure evolution during electrical stressing

We evaluated the electrical properties and change of nanostructure of Cu doped SiO₂ and Ge₂Sb₂Te₅ (GST) thin film under electrical stressing. Specialized scanning tunneling microscopy (STM)-transmission electron microscope (TEM) holder, which allows us to do the electrical characterization and observation of in-situ nano-structural evolution simultaneously, used as a approach method to confirm the devices behavior. The Cu-SiO₂/SiO₂/Si structure observed that Cu nanoclusters, which are not fully crystallized, are randomly distributed. When voltage is applied, Cu becomes to grow and Cu cluster forms a closed packed line, which may a pathway for current flow. For GST/TiW/SiO₂/Si structure, the GST film changed from amorphous phase to localized crystalline phase after electrical stressing. Localized crystallization might be due to the either joule heating or electron beam damages that are still need to be confirmed.