Ion implantation after germanidation (IAG) technique has been implemented for low thermal budget bulk Ge and UTB-GeOI n- and p-MOSFETs. Dopant segregation at NiGe/Ge interface by low temperature drive-in annealing has an advantage in forming an abrupt metallic source/drain (S/D) junction, which is not only effective for bulk Ge but also for UTB-GeOI substrate. IAG technique is proved to be a low thermal budget process for both Ge n- and p-MOSFETs with a high I-on-I-off ratio and low parasitic resistance.