On the Origin of Silicon Lifetime Degradation During Anneal in III-V Material Growth Chambers

Silicon bulk lifetime degradation in III-V material growth chambers has been a major hindrance to the development of III-V/Si tandem solar cells. While the exact mechanisms responsible for this degradation remain unknown, many researchers have attributed such degradation to extrinsic contaminants that diffuse into silicon bulk during growth. In this work, we show that thermal activation of grown-in defects in float zone wafers is also a key mechanism behind such degradation. Annealing of the wafer at 1000 °C to remove these defects, together with a SiN
_X
diffuse barrier layer deposition are both required to preserve the silicon bulk lifetime.