Abstract Mechanism of photo-enhanced diffusion (PED) of Ag was studied from steady and transient photovoltaic current (PVC) in amorphous film of Ge2S3. Both the spectra and the magnitude of the PVC of specimens with Ag electrodes were altered by exposure to light. The changes are consistently ascribed to the diffusion of Ag atoms into the films. In addition to ordinary contact barriers, an electric field is generated at the forefront of the Ag diffused region with the polarity negative to Ag electrode. These results can be explained by the presence of charged defect states in amorphous chalcogenide.