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

摘要

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 Seff of 1.4 cm/s and low-temperature with Seff of 0.9 cm/s (such as LFC) metallization process flows for c-Si solar cells. Combined with Dit and Qtotal results, we believe a large number of oxygen dangling bonds (O DBs) at c-Si/ Al2O3 interface are the critical factor for restructuring interfacial SiOx 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.