Nickel germano-silicide (NiSiGe) contact was formed on silicon-germanium (Si1-xGex or SiGe) epilayer with 26% Ge, grown on p-Si (100) substrate. We report the tuning of the effective Schottky barrier height (SBH) of holes at the NiSiGe/SiGe junction to sub-0.1 eV by the introduction of aluminum (Al) using ion implantation and its segregation at the NiSiGe/SiGe interface after germano-silicidation. The effective SBH decreases with increasing concentration of Al at the NiSiGe/SiGe interface. We demonstrate the achievement of one of the lowest reported hole SBHs for NiSiGe on SiGe of 0.068 eV, which is extremely promising for application in p-type metal oxide semiconductor field-effect transistors. The presence of Al does not affect the sheet resistance or the low-resistivity nickel mono-germano-silicide phase of the NiSiGe film. Our results indicate the possibility of an electric dipole at the NiSiGe/SiGe interface, introduced by Al atoms, which is responsible for the SBH modulation. Increase in thickness of nickel used for germano-silicidation increases the effective SBH. The increase in the Al implant dose reduces the effective SBH but degrades the SiGe epilayer by amorphizing it to a greater depth. Thus, a trade-off exists in choosing the Al implant dose and the nickel thickness needed to consume the amorphized SiGe for maximum device performance.