Comparison between passivation properties of thermal ald Al2O3 deposited with TMA+ O3 and TMA+ H2O

ALD Al₂O₃ can work as excellent passivation dielectric for both p- and n-type c-Si solar cells. In this paper we have demonstrated that ALD Al₂O₃ passivation properties are dependent on the reactants. Al₂O₃ synthesized by thermal ALD with TMA+ O₃ is a robust candidate to be integrated into both high-temperature (screen printed) with Se_ff of 1.4 cm/s and low-temperature with Se_ff of 0.9 cm/s (such as LFC) metallization process flows for c-Si solar cells. Combined with D_it and Q_total results, we believe a large number of oxygen dangling bonds (O DBs) at c-Si/ Al₂O₃ interface are the critical factor for restructuring interfacial SiO_x during post deposition thermal treatment, and in turn improve passivation properties. However Al₂O₃ with reactants of TMA+ H₂O may be only suitable for low temperature metallization process, as hydrogen which passivates O DBs will escape and make O DBs active during the thermal process, which causes passivation properties to degrade.