Investigating subsurface damages in semiconductor-insulator-semiconductor solar cells with THz spectroscopy

The influence of near-surface crystal damage on carrier dynamics in silicon has been investigated with optical-pump THz-probe and THz emission studies. The surface damage is caused by a plasma process used for the fabrication of the ultrathin insulator within semiconductor-insulator-semiconductor (SIS) solar cells. The ion bombardment during the plasma process introduces a highly damaged subsurface region. Furthermore, the integration of positive interface charges leads to the formation of a depletion region that can be detected via the emitted THz radiation. The results are compared with classic I-U-characterization demonstrating that THz spectroscopy can be used as a supplementary tool for the investigation of process-induced surface damages.