INVERSE-PHOTOEMISSION STUDY OF THE CONDUCTION BANDS IN AMORPHOUS GESE2

The unoccupied electronic structure of amorphous GeSe2 has been invest igated by means of inverse-photoemission spectroscopy. We have found p rominent peaks at 2.1 and 4.7 eV above the Fermi level, and another we ak and broad peak at about 8 eV. The energy positions of these peaks a re consistent with those of the calculated density of states of conduc tion bands and those expected from the imaginary part of dielectric fu nction obtained by the optical reflectance measurement. By comparison with the Ge 2p,3d, and Se 3d core-absorption spectra, the first and se cond peaks are assigned to the antibonding states of the Ge-Se covalen t bonds, and the third peak corresponds to the 4d and/or 5s states of both the Ge and Se atoms.