The morphology and re-crystallisation behaviour of thick molecular bea
m epitaxial as-grown and thermally annealed Al films on (100) GaAs is
reported. The re-crystallisation of (110) Al phases to (100) Al procee
ds vertically and substrate driven with simultanuous formation of spha
lerite phases in the (100) Al, giving the overall appearance of an int
erdiffused layer of 60-100 Angstrom.