Effect of UV illumination on the passivation quality of AlOx/c-Si interfaces

We report on the stability of the c-Si surface passivation quality by aluminum oxide (AlO_x), silicon nitride (SiNp), and AlO_x/SiN_y stacks under UV illumination. Low-temperature annealed AlO_x shows a weak degradation during UV illumination, with surface recombination velocities (SRVs) of 25 cm/s after a UV dose of 275 kWh/m². This degradation is less pronounced compared to that of fired SiN_y layers with an SRV of 117 cm/s. After a firing step, the AlO_x layer show even an improvement during UV illumination, resulting in stabilized SRVs of down to 1 cm/s. The improvement is mainly due to an increase of the negative fixed charge density in the AlO_x layer up to a large value of -1.2×10¹³ cm^-2.