Self-Assembled Sn Nanocrystals as the Floating Gate of Nonvolatile Flash Memory

As demands for data storage capability continue to increase, nonvolatile memory devices with discrete nanocrystals as the charge-storage nodes are being extensively investigated. To alleviate scaling issues, use of metal-nanocrystal-based ultrahigh-bit-density memory devices, capable of multilevel cell operations, have been proposed and studied widely. Here we propose a nonvolatile floating gate memory, utilizing nanocrystals of the group-IV metal, beta-Tin (beta-Sn), which spontaneously self-assemble on a variety of high-k dielectric oxides and silicon during molecular beam epitaxy at low temperatures. In metal-oxide-semiconductor memory devices, we demonstrate a large memory window (similar to 3 V) at moderate operating voltages of +/- 6 V and investigate the retention and endurance characteristics. The observed results are promising for realization of memory devices, compatible with the silicon complementary-metal-oxide-semiconductor technology.