Search

We report a Raman study of confined In As-like and InP-like longitudinal optical and interface phonons in highly strained short-period superlattices grown coherently on (001) InP substrates by Atomic Layer Epitaxy. A resonant enhancement of the InAs Raman scattering cross-section at the E1gap of InAs appears as the InAs layer thickness increases beyond 2 monolayers. This enhancement indicates that the scattering involves E1-gap excitons strongly confined in the InAs wells when this gap is created. InAs-like confined longitudinal-optic phonons of A1and B2symmetries are observed in both z(x,x)z̄ polarized and z(x,y)z̄ depolarized configurations under InAs E1-gap resonant excitation. This relaxation of the selection rules is analyzed in terms of resonant impurity-induced scattering. It indicates that the symmetry of the exciton wave functions at the L point, which is different from those at the Γ point, allows intraband coupling of heavy-hole and light-hole states via the deformation-potential interaction.