Calculated superlattice and interface phonons of InAs/GaSb superlattices

The phonon spectrum of InAs/GaSb superlattices is calculated with a linear-chain model with interplanar force constants. Apart from confined and extended modes, as found also in GaAs/GaAlAs superlattices, this system shows new modes localized at the interface. These latter modes depend crucially on the nature (InSb or GaAs) of the interface and some of them do not coincide with any other possible superlattice mode. This fact would make them easily experimentally identifiable