Morphological modification of β-FeSi2 on Si(111) by high temperature growth and post-thermal annealing

β-FeSi₂ crystals have been grown on Si(111) substrates, and morphological modification of the β-FeSi₂/Si(111) by high temperature growth and post-thermal annealing was investigated. The morphological feature of the β-FeSi₂ crystals significantly depends on the growth conditions, especially, substrate temperature during growth. The β-FeSi₂ continuous layers with relatively smooth surfaces were grown at the low substrate temperatures of 650-700 °C with exposure of the grown layers to Sb flux during the growth. On the other hand, nano-scaled islands have been grown at the higher substrate temperature of 850 °C. The structural property, interfacial morphology and growth evolution of the β-FeSi₂ islands were examined, and compared with those for the layers grown at a lower substrate temperature. In addition, the morphological evolution of the β-FeSi₂/Si layers by post-thermal annealing was examined, and it was found that the interfacial smoothness between the β-FeSi₂ layers and the Si(111) substrates was improved by the post-thermal annealing on condition that a thin SiO_x amorphous overlayer should be formed on the β-FeSi₂ layer during the post-thermal annealing. The mechanisms of the morphological modification at the β-FeSi₂/Si(111) interface by the post-thermal annealing will also be discussed.