Abstract
In this study we evaluated two approaches to improving the efficiency of amorphous Si/crystalline Si (a-Si/c-Si) heterojunction solar cells by BF 2 ion implantation. First, emitter layer formation was compared for the cases of B and BF 2 ion implantation when using the same 7° tilt angle. Second, emitter layer formation was compared between a 7° tilt angle and a 60° tilt angle when using BF 2 ion implantation. The experimental results reveal that the fluorine in BF 2 passivates the defects at the a-Si and a-Si/c-Si interface, and ion implantation at a high 60° tilt angle forms a shallow solar cell junction. The emitter layer formed by BF 2 ion implantation with a 60° tilt angle in an a-Si/c-Si heterojunction solar cell achieves the highest short circuit current density (J SC ) of 36.85 mA/cm 2 with a conversion efficiency (ν) of 14.41%. © 2012 The Japan Society of Applied Physics.