Thermal atomic layer deposition of AlOxNy thin films for surface passivation of nano-textured flexible silicon

Abstract Aluminum oxynitride (AlO x N y ) films with different nitrogen concentration are prepared by thermal atomic layer deposition (ALD) for flexible nano-textured silicon (NT-Si) surface passivation. The AlO x N y films are shown to exhibit a homogeneous nitrogen-doping profile and the presence of an adequate amount of hydrogen, which is investigated by Time-of-Fight Elastic Recoil Detection Analysis (ToF-ERDA). The effective minority carrier lifetimes are measured after the NT-Si surface passivation; the minimum surface recombination velocity (SRV) of 5 cm-s −1 is achieved with the AlO x N y film in comparison to the Al 2 O 3 and AlN films (SRV of 7–9 cm-s −1 ). The better SRV with AlO x N y film is due to the collective effect of field-effect passivation by the presence of fixed negative charges, and chemical passivation by the presence of hydrogen within the film. The capacitance-voltage, and conductance measurements also are carried out using metal-oxide-semiconductor structure to determine the fixed negative charge density (N i,ox ), and defect density of states (D it ) in the AlO x N y films. The better surface passivation is attributed to unusually large N i,ox of ~6.07 × 10 12 cm −2 , and minimal D it of ~1.01 × 10 11 cm −2 -eV −1 owing to the saturation of Si dangling bonds by the hydrogen within the AlO x N y film matrix after the annealing step.