Improved conversion efficiency of p-type BaSi2/n-type crystalline Si heterojunction solar cells by a low growth rate deposition of BaSi2

The effect of low growth rate deposition (LGD) of BaSi2 on the film quality and performance of silicon heterojunction solar cells was investigated. The total thickness of the BaSi2 layer decreased with increasing LGD duration (tLGD). Analysis using Raman spectroscopy indicated that an amorphous Si (a-Si) phase existed on the surface of the BaSi2 layer. The a-Si on the surface was converted into BaSi2 by post-annealing owing to the diffusion of Ba and Si atoms. X-ray diffraction analysis revealed that LGD improved the rate of a-axis orientation and crystallinity. Post-annealing was also observed to have significantly improved these structural properties. Furthermore, the solar cell performance was observed to be strongly dependent on tLGD, and the highest conversion efficiency of 10.62% was achieved by the p-BaSi2/n-c-Si heterojunction solar cells at a tLGD of 6 min. The improved structure and solar cell properties are attributed to improved atom rearrangement during LGD.