Search documents

Browse topics

Document details

Firing Stability of Doped Polysilicon Passivation Layers
D. Kang, H.C. Sio, D. Yan, J. Stuckelberger, R. Liu, D. Macdonald
Poly Si, Polysilicon, Silicon, TOPCon, POLO
Silicon Materials and Cells
Subtopic: High Temperature Route for Si Cells
Event: 37th European Photovoltaic Solar Energy Conference and Exhibition
Session: 2BO.1.4
188 - 192
ISBN: 3-936338-73-6
Paper DOI: 10.4229/EUPVSEC20202020-2BO.1.4
0,00 EUR
Document(s): paper


We investigate the impact of firing treatment on n-type silicon samples passivated by n+ and p+ polysilicon (polySi)/SiOx structures, and explore the root causes for the degradation of surface passivation quality after firing. Lifetime samples and industrially fabricated solar cell precursors both show stable surface passivation qualities upon firing at temperatures from 600 to 750, but they exhibit a significant loss of surface passivation quality when the peak firing temperature reaches 800. The degradation phenomena cannot be attributed to changes of the crystal structure in the polySi films, as indicated by Grazing Incidence X-ray Diffraction (GIXRD) results. It is found that the dielectric coating layer plays a significant role in the performance of the polySi passivation layers after firing. The hydrogen profiles measured by Secondary Ion Mass Spectrometry (SIMS) suggest that the impact of firing on n+ polySi passivation layers could be related to changes of the hydrogen concentration in the polySi/SiOx/c-Si structure. Surprisingly, it is observed that the surface passivation quality does not monotonically increase with the hydrogen content in the polySi layers. In contrast to n+ polySi, the p+ polySi passivated samples were found to have better thermal stability, with slightly improved recombination current density parameter (J0) after firing. We have also found a possible correlation between the firing stability of polySi layers and their long-term stability upon extended light soaking.