FORMATION OF EPITAXIAL GAMMA-FESI(2) AND BETA-FESI(2) LAYERS ON (111) SI

Polycrystalline beta-FeSi2 layers, 85 nm thick, thermally grown on (111) Si substrates have been irradiated by 25 ns ruby-laser pulses in the energy density range 0.4-1.2 J/cm2. Formation of the epitaxial metastable gamma-FeSi2 has been observed in a selected energy density range. The stability of gamma-FeSi2 has been tested by annealing in the 300-800-degrees-C temperature range. The precipitation of the gamma phase into the stable beta occurred at temperatures above 600-degrees-C. The beta-FeSi2 films maintained epitaxy with Si and presented a reduction of the roughness with respect to the thermally grown film.