Thermal stability of PECVD a-Si1-xCx layers for crystalline silicon solar cell passivation

Abstract

We investigate the thermal stability of the surface passivation of PECVD a-Si1-xCx layers on symmetrical lifetime samples. To study the influence of thermal treatment on the passivation quality, lifetime measurements on symmetrical samples using the quasi transient technique and the quasi steady state technique are performed. The samples are exposed to temperatures up to 600°C. The annealing steps of ten minutes are carried out in H-plasma and N2 ambient and annealing is done cumulatively. After each temperature step effective lifetime and FTIR measurements are performed. Maximum effective lifetimes of 1.2 ms and 1.7 ms are obtained after annealing at 550°C in hydrogen atmosphere generated by a remote H-plasma and N2 ambient, respectively. In the FTIR spectra a reduction of the SiH peak intensity at 2060 cm-1 is observed. The intensity of the other SiH peaks does not change significantly during annealing.