Surface passivation of silicon by rf magnetron-sputtered silicon nitride films

Si-rich silicon nitride (SiNx(:H)) films are deposited on single crystallin e p-type silicon to investigate their properties as a passivation and antir eflection coating for solar cells. The SiNx(:H) films were reactively sputt ered from an intrinsic Si-target in an Ar/N-2/H-2 rf(13.56 MHz) magnetron p lasma at substrate temperatures from 150 degrees C to 350 degrees C. The op tical band gap of Si-rich SiNx(:H) becomes lower than 3 eV which was determ ined from spectral data of the complex refractive index. Infrared spectra s how a strong Si-H band in Si-rich films. The effective surface recombinatio n velocity (SRV) was calculated from the effective life time in SiNx(:H) co vered p-Si wafers by the microwave detected photoconductivity decay (MW PCD ) technique. Very low values for the effective SRV of about 60 cm/s were de termined. The low values of the effective SRV are due to field-effect passi vation. The field-effect passivation of the SiNx(:H)/Si contact is explaine d with the model of a hetero junction. (C) 1999 Elsevier Science S.A. All r ights reserved.