Quantum field induced strains in nanostructures and prospects for optical actuation

We develop the mechanics theory of a phenomenon in which strain is induced in nanoscale structures in the absence of applied stress, due solely to the presence of quantum mechanical confinement of charge carriers. The direct effect of strain on electronic structure has been widely studied in recent years, but the “reverse coupling” effect that we investigate, which is only appreciable in the smallest structures, has been largely ignored even though its effects are present in first principles atomistic calculations. We develop a simple effective mass approach that can be used to model this universal physical phenomenon allowing a transparent scheme to identify its occurrence. We relate quantum field induced strain to acoustic polarons and identify the presence of this effect in density functional theory calculations of strain and quantum confinement in free-standing Si and GaAs quantum dots. Finally, we discuss the use of this quantum confinement induced strain as a mechanism for universal optical actuation in nanowire structures in the context of recent experimental results on carbon nanotubes.