Pattern formation in SiSb system

TL;DR

This study investigates pattern formation in amorphous SiSb thin films during thermal annealing, revealing segregation-driven spinodal-like decomposition and Sb transport mechanisms influenced by pressure and nanocrystalline grain formation.

Contribution

It provides new insights into the mechanisms of pattern formation and Sb transport in SiSb systems under pressure, combining microscopy and spectrometry analyses.

Findings

Stripe-shaped contrast patterns observed in TEM images.

Sb-rich and Sb-depleted regions identified by SNMS.

Differential Sb peak decay rates at interfaces explained by Sb transport and evaporation.

Abstract

Thermal annealing of Si/Si1-xSbx/Si amorphous thin film tri-layer samples (x=18 and 24 at%Sb) under 100 bar Ar pressure results in an interesting pattern formation. In pictures, taken by means of cross-sectional transmission electron microscopy (TEM), stripe-shaped contrast, with three maxima, parallel with the interfaces can be seen. Secondary neutral mass spectrometer (SNMS) measurements revealed that the regions with different contrasts correspond to Sb-rich and Sb-depleted regions. Furthermore, the Sb concentration peaks in the Sb-rich regions, especially at longer annealing times, are different: the peak developed at the Si/SiSb interface closer to the free surface decays faster than that of the inner one closer to the substrate. The pattern formation is interpreted by segregation-initiated spinodal-like decomposition, while the difference of the Sb concentration peaks is explained by the resultant Sb transport to and evaporation from the free surface. The possible role of formation of nanocrystalline grains, in the explanation of the fast transport under pressure as compared to vacuum is also discussed.