OPTICAL INTERBAND PROPERTIES OF SOME SEMICONDUCTING SILICIDES

Optical transmission and reflection as well as ellipsometric studies a re performed for the semiconducting phases CrSi2, MnSix, and Ir3Si5 in the energy region from 0.2 to 5.0 cV. Onsets of strong interband tran sitions are found around 0.5 eV for the former two compounds and 1.2 e V for the latter one. Optical data analysis for the former two compoun ds suggests them to be indirect semiconductors whereas for the latter to be a direct one. Main interband features for CrSi2 and MnSi1.73 app ear between 1 and 2 eV and for Ir3Si5 at 3 cV. An explanation of these findings is given in terms of existing band structure and density of states considerations.