We present thermal conductivity measurements performed in three short-period
(GaAs)_9(AlAs)_5 superlattices. The samples were grown at different
temperatures, leading to different small scale roughness and broadening of the
interfaces. The cross-plane conductivity is measured with a differential 3w
method, at room temperature. The order of magnitude of the overall thermal
conductivity variation is consistent with existing theoretical models, although
the actual variation is smaller than expected