Silicon Surface Passivation by Sputtered Aluminium Oxide: Influence of Annealing Temperature and Ambient Gas

Aluminium oxide (AlOx) films have achieved excellent passivation on crystalline-silicon surfaces. Irrespective of the deposition method, an anneal is required to activate the passivation. In this work, the reaction kinetics of the annealing process for radiofrequency reactively-sputtered AlOx is investigated. The effectiveness of the activation anneal critically depend on the ambient gas. A gas mixture of N2 and H2 is found to be the best annealing ambient for sputtered Al2O3 films, leading to an effective surface recombination velocity Seff of ∼5 cm/s. The experiments indicate that the surface passivation anneal follows an activation energy EA close to 1.1 eV.