Effect of carbon diffusion on performance of thin film c-Si HIT solar cells with a-SiC passivation layer

The effect of carbon diffusion on the performance of c-Si HIT cells with aSi_1-xC_x:H passivation layer is studied. Two HIT cells are fabricated, one with a-Si passivation layer and one with a-SiC layer. SIMS is used to quantify the carbon diffusion into cSi. The results show a significant amount of carbon at the interface and in the c-Si layer. With the carbon diffusion, the V_oc, J_sc and fill factor drop from 0.523V to 0.331V, 24 mA/cm² to 21 mA/cm² and from 56% to 21% respectively. In addition, the peak EQE drops by 4%. The dark current increases from 6.24×10^-4 mA/cm² to 3.50×10^-3 mA/cm² at V=-0.5V. Moreover, the results indicate that the carbon diffusion reduces the overall c-Si lifetime in addition to increasing the amount of D_it at the interface.