Study of hydrogenated AlN as an anti-reflective coating and for the effective surface passivation of silicon

Stacks of aluminum oxide and silicon nitride are frequently used in silicon photovoltaics. In this Letter, we demonstrate that hydrogenated aluminum nitride can be an alternative to this dual-layer stack. Deposited on 1 ohm cm p-type FZ silicon, very low effective surface recombination velocities of 8 cm/s could be reached after firing at 820 °C. This excellent passivation is traced back to a high density of fixed charges at the interface of approximately -1 × 1012 cm-2 and a very low interface defect density below 5 × 1010 eV-1 cm-2. Furthermore, spectral ellipsometry measurements reveal that these aluminum nitride layers have ideal optical properties for use as anti-reflective coatings.