FORMATION OF INTERMETALLIC COMPOUNDS IN Al THIN FILMS VAPOR-DEPOSITED ON Au PLATE.

This paper concerns the measurement of infrared radiance from an Al thin-film surface vapor-deposited on an Au plate in order to investigate the formation and growth of Al-Au intermetallic compounds in the film. The emissivity of the Al-Au alloy is found to increase with an increase in the Au stoichiometry. A step variation of the surface radiance during annealing is also observed. This has been understood to result from the Al//2Au phase appearing on the film first, followed by the alloy, with smaller Al stoichiometry and finally by the AlAu//4 phase covering the surface. The activation energies for the movement of the boundaries between two phases due to the growth of the Al//2Au and AlAu//4 phases through the film were 22. 8 kcal/mol (Al/Al//2Au) and 22. 2 kcal/mol (Al//2Au/AlAu//4), respectively.