We have investigated the high-pressure optical absorption of Iron disilicide, β-FeSi2, thin films(90 nm in thickness) prepared from Si/Fe multilayers on Si (001) with template and SiO2 capping. It is found that the experimental absorption coefficient in the range of photon energy of about 0.3 eV beyond the band gap is a few orders of magnitude larger than the first-principles calculated absorption coefficient. A possible explanation for this large absorption coefficient is the saddle-point exciton effect by the calculated band structure. No critical points with negative hydrostatic pressure coefficients such as those of Si and GaAs are observed in β-FeSi2 near the band gap. The pressure coefficient for the direct band gap of β-FeSi2 is determined to be 15.9 meV/GPa. This small coefficient is due to the negative deformation potential of the valence-band maximum, and the large bulk modulus of β-FeSi2.
|Number of pages||5|
|Journal||Physical Review B - Condensed Matter and Materials Physics|
|Publication status||Published - 2002 Apr 15|
ASJC Scopus subject areas
- Electronic, Optical and Magnetic Materials
- Condensed Matter Physics