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 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) similar to 2.4 fA/cm(2) for Si: P and J(0) similar to 10 fA/cm(2) for Si: B contacts. The contact resistivity for the passivated contacts was found to be 0.46 Omega.cm(2) for the n-type contact and 0.04 Omega.cm(2) for the p-type contact. The IBPC solar cell test structure gave 1-sun V-oc values of 682 mV and pFF = 80%. The benefits of the ion-implanted IBPC cell structure are discussed.