Resonant hyper-Raman scattering in semiconductor quantum dots

Abstract

Resonant hyper-Raman scattering spectra by LO phonon were successfully observed for both CdS and CuBr quantum dots embedded separately in a glass matrix. The respective radii for the former and latter are 2.0 and 3.2 nm, thereby categorized as the strong and weak confinement regime, respectively. It is found that for the CdS dot, the observed excitation spectrum differs from that of resonant Raman scattering, and that the signal arises from interband and intraband Frohlich interaction for CdS and CuBr, respectively. For the latter, the exciton-LO phonon interaction is so strong due to the confinement effect, that up to 5 multiple phonon scattering signals can be observed. Moreover, new electronic excitation states inherent to the respective regimes are also found.