Optical transition properties of β-FeSi2 film

Optical transition of properties of β-FeSi2 film have been investigated by optical transmittance absorption measurement, spectroscopic ellipsometry and reflectivity. Optical transmittance absorption measurement ranging from 0.5 to 1.1 eV revealed the direct transition at E0=0.84 eV, while absorption curve obtained from the spectroscopic measurement in the range of 1.5–4.5 eV implied additional transition at E′=1.05 eV, it is suggested that such additional transition originates from spin–orbit splitting at Γ (center of Brillouin’s zone). Reflectivity goes to the maximum value near Eg, indicating that the joint density of states in the transition at Eg is very high. Another peak which is related with the transition at E′ was also observed in the reflectivity spectra.