Nitrogen Ion Implantation Effect on Silicon Solar Cells for Surface Passivation

Abstract

We investigated the surface passivation of silicon solar cells by nitrogen ion implantation. The nitrogen ion was implanted with the energy of 20 keV at a twist angle of 22.5° from the Si 〈100〉 direction and a tilt angle of 7°. The ion concentration was varied at 1013, 1014, and 1015 N+/cm2. The implanted cell showed the implanted region located below the anti-reflection coating layer. For the low dose cell of 1013 N+/cm2, the nitrogen ion implantation showed increased quantum efficiency, minority carrier lifetime, and conversion efficiency compared to the reference cell. However, as the ion dose was increased, the quantum efficiency, minority carrier lifetime, photoreflectance, and cell conversion efficiency of the fabricated cell decreased. This indicates that nitrogen ion implantation can passivate the surface to increase the cell conversion efficiency with a critical dose of ions.