GaP/Si Heterojunction Solar Cells Grown by Molecular Beam Epitaxy

Maintaining Si bulk lifetime during epitaxial growth of III-V materials on Si is critical for achieving high performance Si-based solar cell devices. In this work, we demonstrate two different approaches in which were able to preserve the Si bulk lifetime during the epitaxial growth by a molecular beam epitaxy (MBE) system, by using SiNx as a coating layer and a phosphorous-rich region as a gettering sink. In order to investigate the solar cell performance, using these two approaches, different MBE grown GaP/Si heterojunction solar cells with different structures were designed, grown, and fabricated. We show that by introducing a phosphorous (P)-rich region (n+Si) between the GaP and Si layers, the efficiency (η) can be significantly increased. The solar cell, fabricated using the phosphorous-rich region, with p-a-Si/aSi/Si/n+Si/GaP structure shows an open-circuit voltage (V
_OC
) of 617 mV, FF of 64%, and η of 13.1%.