Passivation and Electrical Properties of Alumina Layers Deposited by Atomic-Layer Deposition with Different Precursors

The electrical and passivation properties of alumina layers deposited by the atomic layer deposition (ALD) technique with different precursors at different temperatures are analyzed. Herein, a significantly larger density of the negative fixed charge in alumina layers deposited with ozone in comparison to those prepared with water is observed. A part of this negative charge can be successfully removed by the annealing of the samples already at around 250 °C and this negative charge is tentatively ascribed to oxygen interstitials. The effective surface recombination velocity (s eff) is below 2 cm s−1 in all as-deposited alumina layers independent of the deposition conditions and it is significantly smaller in layers prepared with water. The higher s eff in films prepared with ozone can be explained by the higher density of the interface states in these samples as obtained from impedance measurements performed at different ac frequencies and at different biases. The conduction mechanisms in alumina films are also investigated and their difference is discussed.