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RESEARCH PRODUCT

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

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Abstract Aluminum oxynitride (AlOxNy) films with different nitrogen concentration are prepared by thermal atomic layer deposition (ALD) for flexible nano-textured silicon (NT-Si) surface passivation. The AlOxNy 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 AlOxNy film in comparison to the Al2O3 and AlN films (SRV of 7–9 cm-s−1). The better SRV with AlOxNy 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 (Ni,ox), and defect density of states (Dit) in the AlOxNy films. The better surface passivation is attributed to unusually large Ni,ox of ~6.07 × 1012 cm−2, and minimal Dit of ~1.01 × 1011 cm−2-eV−1 owing to the saturation of Si dangling bonds by the hydrogen within the AlOxNy film matrix after the annealing step.