Phosphorus Catalytic Doping on Intrinsic Silicon Thin Films for the Application in Silicon Heterojunction Solar Cells

Parasitic absorption and limited fill factor (FF) brought in by the use of amorphous silicon layers are efficiency-limiting challenges for the silicon heterojunction (SHJ) solar cells. In this work, postdeposition phosphorus (P) catalytic doping (Cat-doping) on intrinsic amorphous silicon (a-Si:H(i)) at a low substrate temperature was carried out and a P concentration of up to 6 × 10²¹ cm^-3 was reached. The influences of filament temperature, substrate temperature, and processing pressure on the P profiles were systemically studied by secondary-ion mass spectrometry. By replacing the a-Si:H(n⁺er with P Cat-doping of an a-Si:H(i) layer, the passivation quality was improved, reaching an iV_OC of 741 mV, while the parasitic absorption was reduced, leading to an increase in J_SC by ∼1 mA/cm². On the other hand, the open-circuit voltage and the FF of a conventional SHJ solar cell (with the a-Si:H(n) layer) can be improved by adding a Cat-doping process on the a-Si:H(i) layer, resulting in an increase in FF by 4.7%_abs and in efficiency by 1.5%_abs.