Molecular dynamics was applied to a variety of SiGe alloys and superlattice structures in order to investigate the production of an unidentified phonon mode. The mode in question, observed in the resulting phonon dispersion relations, was produced around 2.5 - 5 THz. The corresponding spectral energy density data for the SiGe alloys produced varying intensities around this region, with a higher intensity tending towards lower thermal conductivity values. The unidentified mode was produced by the alloy and the non-periodic superlattice structures, whereas in the case of the periodic superlattices, the mode is less conspicuous. Regarding the SiGe compound, the mode was not produced. It is concluded that the atomic disorder within the alloys and non-periodic superlattices induce a stronger intensity of the unidentified mode.