Core-Shell Germanium–Silicon Nanocrystal Floating Gate for Nonvolatile Memory Applications

We have fabricated germanium-silicon (Si/HfSiO_x) core-shell nanocrystal (NC) structures to work as charge storage nodes in NC flash memories. This core shell NC structure was made by doing silane annealing treatment before and after Ge NC deposition. This silicon(Si/HfSiO_x) shell layer can separate the Ge NC from HfO₂ and ambient oxidants in the following process, and reduces low-quality GeO_x, HfGeO_x to metallic Ge. Thus, a more robust interface with low trap density between the high-kappa dielectric and the NCs was achieved, which helps suppress the charges loss due to trap-assisted tunneling of electrons and results in better device performance.