Silicon solar cells with nitrogen-rich SiNx/Si interfacial passivation by low-energy nitrogen-ion implantation

Abstract

We investigated low energy nitrogen ion implantation into the SiNx/Si interfacial layer of silicon solar cells using various energies and fluences, followed by a thermal annealing process. The low energy implanted nitrogen ions penetrated into the SiNx antireflection layer and reached the Si emitter layer. However, ions could not pass through the Ag electrode contact layer and were unable to form the contact passivation layer. A low energy nitrogen ion implanted cell showed the formation of a rich nitrogen layer in the SiNx/Si interfacial area and an increase in electrical performance. With increasing nitrogen ion implantation energy, cells were damaged and suffered decreasing efficiency compared to a reference cell. Increasing the fluence of nitrogen ions also caused a decrease in cell efficiency. After a low temperature annealing process, the cell efficiency recovered almost to the pre-implantation point of the reference cells and showed a similar recovery in their photoreflectance and quantum efficiency. The low-energy nitrogen ion implantation showed the improved cell efficiency of 17.28% for the energy of 12 keV with a fluence of 1 × 1013 cm-2.