Comparison of high quality surface passivation schemes for phosphorus diffused emitters

Abstract

The emitter saturation current density (Joe) of various high quality passivation schemes on phosphorus diffused emitters has been measured and compared. The passivation schemes investigated were: (i) stoichiometric PECVD silicon nitride (SiN), (ii) forming gas annealed and alnealed thin thermal silicon oxides and (iii) double layers of thin thermal oxide and PECVD SiN. Optimised deposition parameters for our PECVD SiN layers have been determined. The best passivation schemes, for all sheet resistances, were an alnealed thin oxide or a thin oxide/PECVD SiN stack with Joe values as low as 5fA/cm2 being measured. The optimised PECVD SiN is, nevertheless, sufficiently good for most silicon solar cells.