Influence of the oxidant on the chemical and field-effect passivation of Si by ALD Al2O3

Differences in Si surface passivation by aluminum oxide (Al2O3) films synthesized using H2O and O3-based thermal atomic layer deposition (ALD) and plasma ALD have been revealed. A low interface defect density of Dit=~1011 eV-1 cm-2 was obtained after annealing, independent of the oxidant. This low Dit was found to be vital for the passivation performance. Field-effect passivation was less prominent for H2O-based ALD Al2O3 before and after annealing, whereas for as-deposited ALD films with an O2 plasma or O3 as the oxidants, the field-effect passivation was impaired by a very high Dit