Atomic layer deposited dielectric and/or semiconducting oxide bilayers for crystalline silicon surface passivation

摘要

This study deals with the silicon surface passivation by thermal ALD deposited oxides bilayer of Hf02/Al203 as well as single layer of Al rich ZnO (AZO) in the form of ZnO and A1203 multilayers. A significant improvement in the effective minority carrier lifetime (xeff~ 1.3ms) of n-type Si is observed after deposition of Hf02(5nm)/Al203(5nm)/Si compared to that of the single layer Al2O3(10nm)/Si (~0.6ms). Better surface passivation is due to a significant increase in the effective charge density in the bilayer system. Also, the sequence of the dielectric layers is found to play an important role in the quality and effectiveness of the passivation. Further, high teff (~1.5ms) is also realized for p-type Si passivated by ALD deposited AZO films as compared to single layer of pure ZnO (~35us) when annealed in hydrogen ambient at 450癈 for 30mins.