Evolution of the silicon bottom cell photovoltaic behavior during III–V on Si multi-junction solar cells production

Abstract

-The evolution of the Si bulk minority carrier lifetime during the heteroepitaxial growth of III-V on Si multijunction solar cell structures via metal-organic vapor phase epitaxy has been analyzed. Initially, the emitter formation produces important lifetime degradation. Nevertheless, a progressive recovery was observed during the growth of the metamorphic GaAsP/Si structure. A step-wise mechanism has been proposed to explain the lifetime evolution observed during this process. The initial lifetime degradation is believed to be related to the formation of thermally-induced defects within the Si bulk. These defects are subsequently passivated by fastdiffusing atomic hydrogen -coming from precursor (i.e. PH 3 and AsH 3 ) pyrolysis-during the subsequent III-V growth. These results indicate that the MOVPE environment used to create the Ill-V/Si solar cell structures has a dynamic impact on the minority carrier lifetime. Consequently, designing processes that promote the recovery of the lifetime is a must to support the production of high-quality Ill-V/Si solar cells.Index Terms -Minority carrier lifetime, III-V on Si, MJSC, Si bottom cell.