XPS-XAES study of charge transfers at Ni/Al2O3/Al systems

✍ Scribed by T.J. Šarapatka

• Publisher: Elsevier Science
• Year: 1993
• Tongue: English
• Weight: 484 KB
• Volume: 212
• Category: Article
• ISSN: 0009-2614
• DOI: 10.1016/0009-2614(93)87104-b

✦ Synopsis

The chemical shift found for nickel core levels indicates the transfer of electrons from the A120, oxide to deposited Ni. This process creates the N1/A1203 surface dipoles, the electric field of which attracts free electrons from elemental Al towards the sample surface. Filling Al,O,/Al interface states with these electrons increases the barrier height. With increasing oxide thickness from 1.5 to 3.2 nm, the magnitude of this effect decreases while the amount of the transferred charge at Ni/AIIO, remains unchanged. For oxide thicknesses from 1.8 to 2.5 nm, UHV annealing of the Ni/A120j/A1 systems, with Ni deposits thicker than the effective amount of 2.5 ML, causes the formation of a NiAl alloy via interdiffusion through the oxide defects, whereas the thinner Ni deposits persist on the A1203 surface.