Improvements in the Passivation of P+-Si Surfaces by PECVD Silicon Carbide Films

We present further results of a surface passivation study of p + -Si emitters by both intrinsic and boron-doped amorphous SiC x films, deposited in two different standard PECVD reactors. For comparison, thermally grown SiO 2 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 SiO 2 exhibits passivating properties comparable to those on n + -Si emitters, PECVD-SiN x is found to even deteriorate the surface passivation, especially after firing (without metal contacts). On the other hand, PECVD-SiC x 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 V oc of 635 mV for a symmetrically 60 Omega/sq BBr 3 -diffused n-type CZ-wafer with a base resistivity of 4.6 Omegacm