POx/Al2O3 stacks: Highly effective surface passivation of crystalline silicon with a large positive fixed charge

Thin-film stacks of phosphorus oxide (POx) and aluminium oxide (Al2O3) are shown to provide highly effective passivation of crystalline silicon (c-Si) surfaces. Surface recombination velocities as low as 1.7 cm s(-1) and saturation current densities J(0s) as low as 3.3 fA cm(-2) are obtained on ntype (100) c-Si surfaces passivated by 6 nm/14 nm thick POx/Al2O3 stacks deposited in an atomic layer deposition system and annealed at 450 degrees C. This excellent passivation can be attributed in part to an unusually large positive fixed charge density of up to 4.7 x 10(12) cm(-2), which makes such stacks especially suitable for passivation of n-type Si surfaces. Published by AIP Publishing.