Enhanced surface passivation of epitaxially grown emitters for high-efficiency ultrathin crystalline Si solar cells

In this work, we demonstrated an enhanced surface passivation of epitaxially grown boron-doped emitters by replacing thermal SiO₂ as a passivation layer of p⁺-emitter employed in a 16.8% efficient 18-μm Si solar cell on stainless steel with plasma assisted atomic layer deposition (ALD) Al₂O₃/PECVD SiN_x stack. For the Al₂O₃/SiN_x stacks on epitaxial p⁺-emitter after post-deposition anneal, the emitter saturation current density (J_0e) values were decreased to 19.5 fA/cm² with the corresponding iV_oc of 688 mV By using advanced surface passivation scheme, further improvement in the V_oc of a present 16.8% efficient ultrathin Si solar cell on steel can be expected.