Surface and interfacial study of half cycle atomic layer deposited Al2O3 on black phosphorus

The interfacial chemistry between the "half cycle" atomic layer deposited (ALD) Al2O3 and black phosphorus (black-P) was examined using in situ X-ray photoelectron spectroscopy (XPS). Two samples, native and freshly exfoliated, are investigated to understand the effect of oxidation on the initial ALD nucleation. It is found that annealing samples in the ALD chamber results in an increase of oxidation, caused most likely by oxygen transferring from surface adventitious contamination. After the half cycle ALD process, the P-oxide concentration increases, indicating interface deterioration during the Al2O3 deposition. Based on the Al2O3 nucleation or growth behavior observed in the half cycle ALD studies, a true ALD growth tends to occur only after formation of a complete monolayer of oxide on the clean black-P surface with minimum oxidation concentration. (C) 2015 Elsevier B.V. All rights reserved.