Manipulation of K center charge states in silicon nitride films to achieve excellent surface passivation for silicon solar cells

High quality surface passivation (S_eff<5cm/s) was achieved on polished float zone and textured p- and n-type solar grade Czochralski silicon substrates by externally injecting and storing positive or negative charges (>±8 × 10¹²cm^-2) into a dual layer stack of Plasma Enhanced Chemical Vapor Deposition (PECVD) Silicon Nitride (SiN _x)/PECVD Silicon Oxide (SiO₂) films using a corona charging tool. We demonstrate long term stability and uniform charge distribution in the SiN_x film by manipulating the charge on K center defects while negating the requirement of a high temperature thermal oxide step.