Effect of rf power on the photovoltaic properties of boron-doped amorphous carbon/n-type silicon junction fabricated by plasma enhanced chemical vapor deposition

The optical and electrical properties of boron doped amorphous carbon thin films using methane and trimethylboron by plasma enhanced chemical vapor deposition are studied with varying the rf power. The optical bandgap is decreased from 2.4 to 1.4 eV with increasing the rf power due to the increase of sp2 carbon. The boron doped amorphous carbon deposited at 300 W shows large photoconductivity (the ratio of conductivity under illumination to under dark) with high spin density. The open circuit voltage of boron doped amorphous carbon/n-Si structure photovoltaic cell is increased with the increase of rf power and then saturates over 100 W. On the other hand, the short circuit current is increased gradually with increasing the rf power up to 300 W.