Electronic and related properties of crystalline semiconducting iron disilicide

Band structure calculations for beta-FeSi2 have been performed by the linear muffin-tin orbital method within the local density approximation scheme including exchange and correlation effects. A detailed analysis of the conduction and valence band structure around high-symmetry points has shown the existence of a quasidirect band gap structure in the material. It is experimentally confirmed that between the threshold energy of optical interband transition of 0.73 eV and the first direct gap transition with appreciable oscillator strength at about 0.87 eV there is a region in which direct transition of low oscillator strength and indirect transitions overlap. That explains the tricky behavior of beta-FeSi2 in experimental investigations demonstrating it to be either a direct or indirect gap semiconductor. (C) 1996 American Institute of Physics.