Investigations of activation energy barriers for Al surface hopping on α-Al2O3

(00•1) surfaces were carried out by means of first-principles density functional

theory calculations and the nudged elastic band method. Results showed that

surface diffusion on the (most stable) Al-terminated surface was relatively fast,

with an energy barrier of 0.75eV, whereas Al hopping on the O-terminated surface

was slower; with barriers for jumps from the two metastable positions on this

surface, to the stable site, of 0.31 and 0.99eV. Based upon this study and upon

literature data, the governing mechanisms during low-temperature α-alumina thin

film growth were summarized. The results supported the suggestions made in some

previous experimental studies, which pointed out that limited surface diffusivity

was not the main obstacle to α-alumina growth at low-to-moderate temperatures,

and that other effects should be considered first when designing new processes for

low-temperature α-alumina deposition.

Low-Temperature α-Alumina Thin Film Growth: Ab Initio Studies of Al Adatom

Surface Migration. E.Wallin, E.P.Münger, V.Chirita, U.Helmersson: Journal of

Physics D, 2009, 42[12], 125302