Formation of silicon nanocrystals embedded in high-$κ$ dielectric $HfO2$ and their application for charge storage

Annealing thin films of silicon containing $HfO2$ films deposited by an electron-beam coevaporation produces silicon nanocrystals embedded in high-$κ$ dielectric $HfO2$⁠. Such films can be used to fabricate nonvolatile memory devices. By changing the Si content in the precursor $HfSixO2$ (⁠$x=1$⁠, 2, 3, or 4) film, the size and density of silicon nanocrystal could be controlled and high-density of silicon nanocrystals could be obtained. Transmission electron microscopy observations showed that the maximum density of silicon nanocrystals was as high as $1.3×1013cm−2$ for $HfSi4O2$ and the average nanocrystal diameter was 4.3 nm. The metal-oxide semiconductor capacitor memory structure with embedded silicon nanocrystals in $HfSi4O2$ exhibited the largest memory window, 3.94 V under ±5 V sweep voltage.