Improved photovoltaic properties of a-Si/β-FeSi2/c-Si double heterojunction by Al-doping

Al-doped β-FeSi2 thin film was sputtered on Si substrate and then applied to the amorphous-Si/β-FeSi2/crystalline-Si (a-Si/β-FeSi2/c-Si) double heterojunction. The X-ray diffraction result confirmed the formation of β-FeSi2 crystallization. The result of carrier lifetime measurement implied that Al-doping could improve the carrier lifetime and infrared response property of β-FeSi2 thin film. Such improvements were ascribed to the reduction of Si vacancy density by Al atom occupation. Based on the improved Al-doped β-FeSi2 thin film, the prepared a-Si/β-FeSi2/c-Si double heterojunction exhibited prominent enhancements in open-circuit voltage, short-circuit current density, fill factor, and energy conversion efficiency than that of the un-doped β-FeSi2 double heterojunction. These results reveal an attractive way to improve the photovoltaic property of a-Si/β-FeSi2/c-Si double heterojunction using Al-doped β-FeSi2 thin film.