We present further results of a surface passivation study of p+-Si emitters by both intrinsic and boron-doped amorphous SiCx films, deposited in two different standard PECVD reactors. For comparison, thermally grown SiO2 and PECVD-SiN x layers with refractive indices of n=2.0 and n=2.4 were examined on the same test structures. While thermal SiO2 exhibits passivating properties comparable to those on n+-Si emitters, PECVD-SiNx is found to even deteriorate the surface passivation, especially after firing (without metal contacts). On the other hand, PECVD-SiCx yields, to our knowledge, the best p +-Si passivation so far obtained by an industrially relevant low temperature process. It is expressed by an implied Voc of 635 mV for a symmetrically 60 Omega/sq BBr3-diffused n-type CZ-wafer with a base resistivity of 4.6 Omegacm