Dislocation plasticity and phase transformations in Si-SiC core-shell nanotowers

Abstract

Vapor-liquid-solid (VLS) Si nanotowers were coated with nanocrystalline SiC to form a Si-SiC core-shell composite. Due to a mismatch in the coefficients of thermal expansion (CTE), the Si core was under a compressive stress following the deposition. The composite tower was then cross-sectioned using focused ion beam milling, exposing the Si core. Indentation into the Si showed an increased toughness as a function of diameter compared to similar sized Si nanotowers and nanospheres. This result is explained through enhanced dislocation and phase transformation plasticity in the Si core from the CTE compressive stresses.

Shell-Thickness Controlled Semiconductor–Metal Transition in Si–SiC Core–Shell Nanowires

“…Indeed, the possibility of increasing the interface quality in 3C-SiC–Si epitaxial layers has been demonstrated in many different experimental works. − These ideas can be in principle transferred to the nanowire geometry, and in fact, single crystalline Si core SiC shell NWs with abrupt, well-defined interfaces have been reported recently . However, despite a few experimental reports on the growth of Si–SiC core–shell nanostructures, − little is known about their electronic properties.…”

Si NWs Conversion to Si-SiC Core-Shell NWs by MBE

“…However, most of the studies show poor crystalline quality. It seems difficult to obtain monocrystalline Si-SiC core-shell NWs without defects like voids, SFs and low residual doping with the low cost "chemistry-driven" methods used up to now [6]. Here, Molecular Beam Epitaxy is shown to be an alternative method to improve the Si-SiC core-shell NWs crystalline quality [1].…”