Interdigitated Back Passivated Contact (IBPC) Solar Cells Formed by Ion Implantation

Abstract

We describe work toward an interdigitated back passivated contact (IBPC) solar cell formed by patterned ion-implanted passivated contacts. Formation of electron and hole passivated contacts to n-type Cz wafers using a thin SiO2 layer and ion-implanted amorphous silicon (a-Si) is described. P and B were ion implanted into intrinsic a-Si films, forming symmetric and IBPC test structures. The recombination parameter $J_{0}$ , as measured by a Sinton lifetime tester after thermal annealing, was $J_{0}$ ∼ 2.4 fA/cm2 for Si:P and $J_{0} \sim10$ fA/cm2 for Si:B contacts. The contact resistivity for the passivated contacts was found to be 0.46 Ω·cm2 for the n-type contact and 0.04 Ω·cm2 for the p-type contact. The IBPC solar cell test structure gave 1-sun $V_{{\rm oc}}$ values of 682 mV and ${\rm pFF} = 80\%$ . The benefits of the ion-implanted IBPC cell structure are discussed.