Characterization of industrial p-type CZ silicon wafers passivated with a-SiCx:H films

In this work we investigate the impact of surface passivation on the efficiency of solar cells produced on industrial p-type Czochralsky(CZ)-grown crystalline silicon wafers as those used in the standard fabrication process of ISOFOTON. The investigation has two objectives. The first objective is to estimate the bulk minority carrier lifetime of the CZ silicon material. For this purpose the effective minority carrier lifetime of silicon wafers with different thicknesses is determined using the quasi steady-state photoconductance (QSS-PC) method. To eliminate the effect of surface recombination, amorphous silicon carbide films are deposited by plasma enhanced chemical vapour deposition (PECVD) on both wafer surfaces. The second objective is to find out how solar cell parameters like open circuit voltage and efficiency are modified when simultaneously to a wafer thickness reduction an effective back surface passivation is applied. This is done through the analysis of injection level dependent lifetime data together with PC-ID simulation.