For CoCp2, when comparing H-terminations and NHx-terminations, the energy gain on the NHx-terminated Si(100) surface, -0.21eV, is more favourable than on H-terminated Si, 0.12eV. This provides further evidence that the plasma generated NxHy radicals are essential to promote Co metal deposition in addition to preventing metal oxidation. From our results, we suggest that if we apply an N-plasma (NH3 or mixture of N2 and H2) treatment on the H:Si(100) substrate as the first step in Co ALD with CoCp2, the incubation period can be reduced. In addition, the differences we see for surface reactivity also suggest the possibility of area-selective ALD mediated by these NHx-terminations and H-terminations.