Electronic excitations in narrow quantum wells via intersubband Raman scattering: Theoretical considerations

In this work a generalized self-consistent field theory was applied to investigate the elementary excitations of two-dimensional electron gas formed from narrow quantum wells via resonant intersubband Raman scattering. The developed model considers the existence of equally coupled and degenerated excitations of the electron gas and allows to observe that in extreme resonance regime the plasma oscillations splits into two contributions: a set of renormalized collective excitations (plasmons) and unrenormalized electronic transitions (single-particle excitations). Our results show that the asymmetries which appear in the Raman profile of doped narrow quantum wells can be interpreted as the entrance or exit of resonance of collective modes overlapped with single-particle transitions.