InSb nanocrystals embedded in SiO2: Strain and melting-point hysteresis

In this work we demonstrate that InSb nanocrystals embedded in SiO₂ display a substantial melting-point hysteresis. Transmission electron microscopy was performed after heat treatment on the 500 nm-thick SiO₂ films doped with 10 at.% of In and Sb atoms in order to verify the presence of the nanocrystals, identify their crystalline form, and obtain their size distribution. The crystalline zinc-blende structure of the InSb nanocrystals was further confirmed with X-ray diffraction characterization. The planar distances and the cubic structure were derived from the X-ray diffraction spectrum. Furthermore, it showed that the nanocrystals have a planar distance slightly smaller than for the bulk crystals, indicating that the nanocrystals are exposed to a compressive stress which we estimate to be 14 kbar. Both superheating and supercooling of the nanocrystals could be observed by following the diffraction pattern of the nanocrystals using TEM. The melting-point hysteresis was measured to be about 19% of the melting temperature of bulk InSb.