An investigation of the recombination mechanisms associated with the X states in type II GaAs/AlAs superlattices

We present a new examination of the phonon modes participating in the recombination processes from type II GaAs/AlAs superlattices. This is achieved through the use of a novel Raman resonance at the type II band gap, which provides a very precise, in-situ measurement technique for the important phonon energies. These are compared with the energies of the phonon satellites appearing in the photoluminescence emissions, using external uniaxial stress to access, in turn, the optical properties of both the longitudinal and transverse X states. Not only do these measurements resolve an existing controversy in the assignment of one of these satellites, but they also demonstrate that two of the others are currently in error, and re-assignments are proposed.