High Density Formation of Ta Nanodots Induced by Remote Hydrogen Plasma

We have demonstrated the formation of high-density Ta nanodots (NDs) on thermally-grown SiO$_{2}$ by exposing electron beam evaporated a-Ge/Ta bi-layer stack to remote H$_{2}$ plasma without any external heating. After the remote H$_{2}$ plasma exposure, the formation of NDs with an areal density of 9.7 $\times$ 10$^{11}$ cm$^{-2}$ and an average height of $\sim$ 2.1 nm was confirmed. The electrical separation among the Ta-NDs was observed from changes in surface potential due to charging to the dots. XPS analyses indicate etching of a-Ge layer by the remote H$_{2}$ plasma exposure, which was accompanied with agglomeration of Ta atoms on the SiO$_{2}$ surface caused by local heating associated with the recombination of atomic hydrogen on clean Ta-layer surface.