Abstract
The effect of copper on the photodarkening property of glassy (Ge0•95Sn0·05Se2)1−x Cu x films has been studied. Photodarkening is not observed for x ≥0·10. The results of the studies show that there is a correlation between the presence or absence of photodarkening and changes in the other measured parameters, such as the optical gap, the refractive index and the density. It is concluded that the absence of photodarkening is not a consequence of a masking effect due to a reduction in the optical gap. Rather it is related to a change in the structure of the glass network.