  Combined gold and silicon nano-system has spurred tremendous interest in the
scientific community due to its application in different metal-semiconductor
electronic devices and solar driven water splitting cells. Silicon, fabricated
on gold layer, is prone to gold atom diffusion at its surface. In this study,
detailed analysis of mechanical properties of gold coated silicon nanowafer is
studied by performing molecular dynamics tensile and compressive simulations.
The effects of temperature, gold coating thickness, strain rate and
crystallographic orientation of silicon on the mechanical properties are
observed for the nanowafer. It is found that both the ultimate tensile and
compressive strength show inverse relationship with temperature. The nanowafer
fails mainly by slipping along {110} plane due to excessive shear when loaded
in [100] direction while a mixed slip and crack type failure occurs for 300K.
Interesting crystallographic transformation from fcc to hcp crystal is observed
in gold layer for the highest gold layer thickness during tension. The effects
of strain rate in tension and compression is also studied. Finally, the crystal
orientation of silicon is varied and the tension-compression asymmetry inn the
gold coated silicon nanowafer is investigated. Reverse tension-compression
asymmetry is observed in case of loading along [110] crystal orientation. The
failure mechanism reveals that interesting crystal transformation of silicon
occurs during compression leading to early yielding of the material.
