Silicon Solar Cell With Integrated Tunnel Junction for Multijunction Photovoltaic Applications

A silicon (Si) solar cell structure with an integrated Si tunnel junction (TJ) is proposed for multijunction (MJ) solar cell applications. The TJ is fabricated on top of an ordinary Si solar cell via the proximity rapid thermal diffusion process. The fabricated solar cells with integrated TJs show nondegraded photovoltaic characteristics. The electrical performance of the TJs allows for normal operation of Si-based MJ solar cells under at least 250-sun illumination and can be improved to achieve compatibility for higher illumination levels. The structure reported in this letter serves as a promising candidate for use as a bottom cell with an integrated TJ for low-cost and high-efficiency MJ solar cells.