Interface defects in a-Si:H/c-Si heterojunction solar cells

The ability to incorporate a low concentration of defects at different near-surface or interface locations in a silicon heterojunction solar cell is reported here using argon ion implantation. Optical properties of the irradiated layers are addressed using spectroscopic ellipsometry while non-radiative recombinations through defects are addressed using photoconductance and photoluminescence measurements. Low energy ion irradiation at 1 keV under fluences up to 7 × 1013 cm−2 induces no cell degradation while higher ion energies associated to larger penetration depths close to the amorphous/crystalline interface show increased degradation with ion fluence. This behavior allows to estimate some interface defect concentration threshold for cell degradation.