The influence of annealing on the passivation quality of A-SiCX:H on crystalline silicon and germanium surfaces

This paper is addressed to the surface passivation of c-Si and c-Ge wafers by plasma enhanced chemical vapor deposition (PECVD) of Si-rich a-SiCx. We report upon excellent effective lifetimes on 1 ¿cm CZ p-Ge substrates exceeding 400 ¿s after an annealing step of 450°C. The comparison of the thermal stability of the passivation quality on the respective substrates reveals experimentally, that contrary to the system c-Si/a-SiCx, hydrogen plays a minor role in the electrical passivation of c-Ge surfaces by a-SiCx. This phenomenon is discussed considering the different work functions and band gaps of the respective materials and different possibilities for the role of carbon in the passivating matrix are outlined.