Polycrystalline semiconducting β-FeSi2 layers on Si (100) have been formed by ion beam synthesis. Results from two different annealing processes, either two-step (2SA) annealing up to 900°C or three-step annealing (3SA) up to 1100°C, are discussed. β-FeSi2 grown by 3SA has shown a typical direct band-gap energy (Edir g) of 0.88 eV and a high localized defect density (N0) of 1.0 × 1018 cm-3, the latter being due to crystallographic mismatches or relevant defects at grain boundaries introduced during the transformation process from β to α. On the contrary, β-FeSi2 grown by 2 SA has shown a lower Edir g of 0.80 eV and a smaller N0 of 1.7 × 1017 cm-3, the former arising from a deviation of the stoichiometric composition to the Si-rich side. Broad PL bands near 0.8 eV have been observed at 2 K from both 2SA and 3SA samples, and we assign these PL bands to optical radiative transitions intrinsic to β-FeSi2.
|ジャーナル||Japanese Journal of Applied Physics, Part 1: Regular Papers and Short Notes and Review Papers|
|出版ステータス||Published - 1997 5|
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