Optical Properties of Indium Oxide

In an investigation of the fundamental optical absorption edge of indium oxide at room temperature, transitions identified as direct‐allowed have been observed with an energy gap (probably at k=0) of 3.75 eV. Indirect‐forbidden transitions have also been observed with an energy gap of 2.619 eV and an assisting phonon of 0.069 eV. It is proposed that the minimum of the conduction band is at k=0 and the maximum of the valence band is at k≠0.