Characterization of a-SiC x :H Films for c-Si Surface Passivation

Amorphous intrinsic silicon carbide (a-SiC x :H(i)) films and amorphous phophorous doped silicon carbide (a-SiC x :H(n)) films deposited by plasma enhanced chemical vapor deposition (PECVD) from silane/methane mixtures provide excellent electronic passivation of p-type c-Si. Effective surface recombination velocities (S eff ) lower than 23 cm s -1 have been reported for a- SiC x :H(i) films and S eff < 11 cm s -1 for a-SiC x :H(n) films. The analysis of the dependence of Seff on the injection level indicates that the good electronic passivation is due to field-effect passivation resulting from a high fixed charge (Q f ) created in the a-SiC x :H film. In this work the absorption of SiH bonds in infrared transmission spectra of a-SiC x :H films is quantitatively analysed resulting in about 30% smaller amount of SiH bonds in phosphorous doped films compared to intrinsic films. Furthermore, a strong reciprocal correlation of the hydrogen content in the films and the Q f created at the a-SiC x :H/c-Si interface is observed.