LAUSR

Aluminum oxide thin films fabricated via atomic layer deposition are introduced as passivating tunneling interlayers between hole-selective molybdenum oxide contacts and silicon absorbers. Surface recombination velocity and specific contact resistivity are reported as a function of Al₂O₃ thickness. The effects of substrate chemical pretreatment, the thermal history of the Al₂O₃ layers prior to MoO_x deposition, and the thermal history of the completed Al₂O₃/MoO_x stacks were also investigated. When an SiO_x/Al₂O₃ passivating stack was incorporated and the completed test structure was annealed at 200 °C, the observed recombination velocities were reduced from ∼10 000 cm/s for an unpassivated (initially hydrogen-terminated) Si/MoO_x direct contact to ∼500 cm/s, while maintaining a contact resistivity at or below 0.1 Ω·cm². The data demonstrate the capability of ultrathin Al₂O₃ to improve Si/MoO_x contact properties and may be of interest in the design of future Si heterojunctions.