Very low surface recombination velocities on p- and n-type c-Si by ultrafast spatial atomic layer deposition of aluminum oxide

Using aluminum oxide (Al2O3) films deposited by high-rate spatial atomic layer deposition (ALD), we achieve very low surface recombination velocities of 6.5 cm/s on p-type and 8.1 cm/s on n-type crystalline silicon wafers. Using spatially separated reaction zones instead of the conventional time-sequenced precursor dosing enables growth rates up to 70 nm/min, whereas conventional ALD limits the growth rate to <2 nm/min. The excellent passivation level is predominantly assigned to a high negative fixed charge density of Qf=−(4±1)×1012 cm−2 in the Al2O3 films. We demonstrate an excellent thermal stability of the passivation quality.