Raman spectroscopy of phonons in optically confined semiconductor nanostructures

Abstract

We describe two alternative schemes for optical resonant Raman enhancement using semiconductor planar microcavities. These geometries, which rely either on the angular tuning of laser and scattered photons, or alternatively on double mode structures, allow for inelastic light scattering amplifications of up to 105. We overview results of a series of investigations of phonon Raman scattering in semiconductor nanostructures which exploit this microcavity enhancement. These include standing optical phonons observed in multiple quantum wells made of only a few periods, and finite-size effects observed on the folded acoustic phonon spectra of these structures. Based on these results and on the concept of cavity confinement, we propose a novel phonon microcavity structure and demonstrate through Raman scattering experiments in an optical microcavity the existence of acoustical phonon confined modes in these structures.