Valence and conduction band discontinuities in AlAs-GaAs heterostruc-tures have been tuned through fabrication of epitaxial Ge layers at the interface. The local interface dipole associated with the Ge layer can be added to, or subtracted from the natural band offsets depending on the growth sequence. Comparison with earlier results for AlAs-Si-GaAs heterostructures, shows that the observed dipole is consistent in direction and order of magnitude for Ge and Si interface layers. The dipole initially increases with interface layer thickness more rapidly for Ge than for Si, however the total maximum dipole achievable at the interface is identical (0.4eV), within experimental uncertainty, for the two group IV elements.