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

摘要

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 (N-i,N-ox), and defect density of states (D-it) in the AlOxNy films. The better surface passivation is attributed to unusually large N-i,N-ox of similar to 6.07 x 10(12) cm(-2), and minimal D-it of similar to 1.01 x 10(11) cm(-2)-eV(-1) owing to the saturation of Si dangling bonds by the hydrogen within the AlOxNy film matrix after the annealing step.