Fano interference in intrasubband Raman scattering of semiconductor superlattices

Fano's theory is used to study the interaction between a continuum of Raman-active electronic intrasubband transitions and a discrete LO-phonon state in a semiconductor superlattice (SL). An explicit analytical expression of the asymmetry parameter q has been derived, which indicates the possibility of the occurence of Fano interference in intrasubband Raman scattering in suitably designed SL structures. The analytical expression clearly shows that q not only depends strongly on the SL parameters, but also depends sensitively on the exciting wavelength. The corresponding suitable design and preparation of SL samples and the performance of Raman experiments have also been carefully carried out for the first time. The theoretical calculations and experimental measurements show good qualitative and quantitative agreement.