Investigation of variously composed p/i junctions in amorphous silicon solar cells by time of flight and spectral response measurements

Amorphous p-SiC/Si heterojunctions with carbon or phosphorus buffer layers were investigated by spectral response and delayed field measurements. Both buffer types enhance the carrier lifetime at the interface and the blue response. The compensate for the negative influence of cross-contaminated boron, the primary origin of low blue response. A model of a buffer layer conceived to operate efficiently demonstrated the correlation between the length of the carbon buffer layer and the boron cross contamination. In addition the interface lifetime depends on the deposition sequence. Deposition of undoped SiC onto a-Si:H is associated with shallow electron traps, while the reverse sequence shows a very low interface state density.