Screen Printed Fire-Through Contact Formation for Polysilicon-Passivated Contacts and Phosphorus-Diffused Contacts

In this article, we investigate the passivation quality and electrical contact properties for samples with a 150 nm thick n
⁺
polysilicon layer in comparison to samples with a phosphorus diffused layer. High level of passivation is achieved for the samples with n
⁺
polysilicon layer and an interfacial oxide underneath it. The contact properties with screen-printed fire-through silver paste are excellent (no additional recombination from metallization and specific contact resistivity (ρ
_c
) ≤ 2 mΩ·cm
²
) for the samples with the polysilicon layers. Fast-firing peak temperature was varied during the contact formation process; this was done to see the trend in the contact properties with the change in the thermal budget. The differences in the
J
_0met
and
ρ_c
for the two different kinds of samples are explained with the help of high-resolution scanning electron microscope imaging. Finally, we prepare M2-sized n-passivated emitter rear totally (PERT) diffused solar cells with a 150 nm thick n
⁺
polysilicon based passivated rear contact. The best cell achieved an efficiency of 21.64%, with a V
_oc
of 686 mV and fill factor of 80.2%.