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Heterojunction solar cells with Al-alloyed polycrystalline p-type β-phase iron disilicide [p-β-FeSi 2 (Al)] on n-Si (100) were investigated. The p-β-FeSi 2 (Al) was grown by sputter deposition and rapid-thermal annealing. Photocurrent of∼ 1.8 mA/cm 2 and open-circuit voltage of∼ 63 mV were obtained for p-β-FeSi 2 (Al)/n-Si (100)/Ti/Al control cells with indium-tin-oxide (ITO) top electrode. Open-circuit voltage increased considerably once thin Al layer was deposited before amorphous-FeSi 2 (Al) deposition. Furthermore, device performances were found to improve significantly (⁠∼ 5.3 mA/cm 2 and∼ 450 mV⁠) by introducing germanium-nitride electron-blocking layer between ITO and p-β-FeSi 2 (Al)⁠. The improvement is attributed to the formation of epitaxial Al-containing p+-Si at p-β-FeSi 2 (Al)/n-Si (100) interface and suppressed back-diffusion of photogenerated electrons into ITO.