Recent progress in BaSi2 solar cells

We fabricated p-BaSi₂/n-Si solar cells by forming a 20-nm-thick B-doped p-BaSi₂ epitaxial layer (p = 2.2 × 10¹⁸ cm^-3) on an n-Si(111) substrate (ρ = 1-4 Ω cm) by molecular beam epitaxy (MBE). 3-nm-thick amorphous-Si was deposited on the p-BaSi₂ surface to prevent the surface oxidation. According to the band alignment of p-BaSi₂/n-Si heteroj unction, the separation of photogenerated minority carriers is promoted at the heterointerface. We recorded conversion efficiency of 9.0 % under AM1.5 illumination at 25°C. Short-circuit current density of 31.9 mA/cm², open-circuit voltage of 0.46 V, and fill factor of 0.60 were obtained. These results suggest the potential of BaSi₂ for solar cell application.