AN INVERSE-PHOTO-EMISSION STUDY ON THE PHOTO-DISSOLUTION OF AG AND CUMETALS IN AMORPHOUS GESE2

The conduction-band density of states of amorphous (a-) GeSe2 photo-di ssolved by Ag and Cu metals has been examined by means of inverse-phot o-emission spectroscopy (IPES). The characteristic feature of the IPES spectrum of a-GeSe2 rapidly smears out with the photo-dissolution of Ag or Cu metal, and each spectrum of the fully photo-doped samples is quite similar to that of a-GeSe1.5. This result is consistent with a s tructural model in which the dopant atoms are surrounded by four Se at oms and many Ge-Ge bonds are induced by photo-dissolution. We also mea sured the change of the IPES spectra in the process of Ag photo-doping .