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 500nm-thick SiO2 films doped with 10at.% 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 14kbar. 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.