An Enhanced Adiabatic Bond Charge Model is applied to a variety of semiconductor nano-patterned structures to examine their phononic behaviour. We apply this approach to determine the locations and widths of phononic band gaps, and negative phonon group velocities, for both longitudinal acoustic and transverse acoustic modes, in the nanosized Si(4 nm)/Si0.4Ge0.6(8 nm) superlattice. In addition to reproducing the LA band gaps observed recently by Ezzahari and co-workers using a picosecond technique, we predict this superlattice to be a true one-dimensional phononic system in the hypersonic range. We show that embedded wires of Ge in Si can be either a one-dimensional or an optical phononic crystal and that Sn wires embedded in Si can also be a 2D phononic crystal.
Transport and Optical Properties of Nanomaterials
- Pub Date:
- June 2009
- Low-dimensional mesoscopic and nanoscale systems: structure and nonelectronic properties;
- Semiconductor devices;
- Layered systems