INVERSE-PHOTOEMISSION SPECTRA OF AMORPHOUS CHALCOGENIDES

Unoccupied density of states (DOS) of amorphous (a-) As2Se3 was examin ed by inverse-photoemission spectroscopy (IPES). The IPES spectrum has a prominent peak at 3.1 eV and a weak shoulder around 7.5 eV above th e Fermi energy, E(F). By comparing with the core-absorption spectra, o rbital characters of the conduction-band DOS's were discussed, and it was found that the bottom of the conduction bands is composed of both the As and Se 4p states. The joint density of states obtained by the c onvolution of the photoemission and inverse-photoemission spectra was also discussed by comparing with the imaginary part of the dielectric function. We also measured the IPES spectrum of a-Se, and discussed it s conduction-band DOS's.