Filling-in of the pseudogap in amorphous Mg—Bi alloys

The optical properties of amorphous Mg-Bi alloys have been studied in the near infrared and visible spectral regions. Amorphous Mg₃Bi₂ is found to be a semiconductor with a band gap of 0.152 ± 0.005 eV. Excess Mg or Bi in amorphous Mg₃ Bi₂ is shown to form localised states near the Fermi level which fill in the pseudogap. These results are inconsistent with the rigid band model proposed by Ferrier and Herrell.