Strain Nano-Engineering: SSOI as a Playground

Ultrathin strained silicon-on-insulator (SSOI) has been in the limelight of device scientists and engineers as one of the materials that can possibly extend the lifetime of the current silicon technology. In this paper, we show that, beyond this technological interest, SSOI also provides a rich platform to explore and explain a number of fundamental phenomena. In particular, ultrathin SSOI substrates are exploited to elucidate basic nanomechanical properties of silicon. Particularly, the bending associated with free surface-induced relaxation upon nanoscale patterning are investigated using micro-Raman scattering, high resolution transmission electron microscopy, and nano-beam electron diffraction. The observed morphological changes in SSOI nanostructures cannot be explained by the classical Stoney's formula or related formulations developed for nanoscale thin films. Instead, a continuum mechanical approach is employed to describe these observations through three-dimensional numerical calculations of relaxation-induced lattice displacements. The use of SSOI to implement novel nanoscale devices is also discussed.