Phonon lifetimes in model quantum dot superlattice systems with applications to the hot carrier solar cell

The lifetime of high energy phonons in a QD superlattice is computed for plausible model materials from Time Dependent Perturbation Theory (TDPT). Klemens decay can be inhibited for a range of high energy phonons if a significant phonon bandgap exists. Ridley-type decays can compete with Klemens for speed due to the large density of states available for decay products on some decay paths and are typically a few picoseconds. In diamond superlattices where QDs occupy the majority of the unit cell, computed lifetimes can be as long as hundreds of picoseconds for certain symmetry directions. (C) 2010 Elsevier B.V. All rights reserved.