The electronic structure of Cu-modified arsenic chalcogenides

X-ray photoelectron and emission spectroscopies have been used to study the electronic structure of Cu-x(As2S3)(1-x) and Cu-x(As2Se3)(1-x) compounds a cross the range where the amount of Cu in the sample strongly affects the p hotodarkening (PD). Shifts of the As 3d, S 2p and Se 3d core level energies in Cu-contdning samples indicate Cu bonding to As as well as to the chalco gen atoms. These shifts are largest in the selenide compounds. Low-temperat ure (similar to 0.4 K) anomalies and vectoral photoinduced effects are foun d to be much less affected by the Cu addition than is the PD, (C) 2000 Else vier Science B.V. All rights reserved.