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 approximatio n scheme including exchange and correlation effects. A detailed analys is of the conduction and valence band structure around high-symmetry p oints has shown the existence of a quasidirect band gap structure in t he material. It is experimentally confirmed that between the threshold energy of optical interband transition of 0.73 eV and the first direc t gap transition with appreciable oscillator strength at about 0.87 eV there is a region in which direct transition of low oscillator streng th and indirect transitions overlap. That explains the tricky behavior of beta-FeSi2 in experimental investigations demonstrating it to be e ither a direct or indirect gap semiconductor. (C) 1996 American Instit ute of Physics.