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

We describe work toward an interdigitated back passivated contact (IBPC) solar cell formed by patterned ionimplanted passivated contacts. Formation of electron and hole passivated contacts to n-type Cz wafers using a thin SiO2layer 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 J0, as measured by a Sinton lifetime tester after thermal annealing, was J0~ 2.4 fA/cm2for Si:P and J0~ 10 fA/cm2for Si:B contacts. The contact resistivity for the passivated contacts was found to be 0.46 Ω·cm2for the n-type contact and 0.04 Ω·cm2for the p-type contact. The IBPC solar cell test structure gave 1-sun Vocvalues of 682 mV and pFF = 80%. The benefits of the ion-implanted IBPC cell structure are discussed.