Electronic Properties of Materials with Gross Permanent Photoinduced Changes: Cu–As–Se Glasses

Abstract

Fundamental physical properties of Cu–As–Se glasses along \(\mathrm{Cu}{ - }{\mathrm{As}}_{2}{\mathrm{Se}}_{3}\) tie lines have been investigated in order to obtain information on the electronic structure. Progressive addition of Cu to As2Se3 induces a gradual red shift of the absorption edge and significantly reduces the value of dark conductivity and its activation energy. The latter is also confirmed by thermally stimulated depolarisation current experiments. Taken together, all of the data, including steady-state photoconductivity measurements, indicate that the “electrical” and “optical” band gaps gradually narrow with Cu addition. It is established that Cu addition in As–Se glasses causes a significant change in the dark conductivity value and its activation energy. Cu–As–Se glasses are photoconductive and the temperature dependence is normal, showing the expected slope in the low-temperature region below the maximum. Thermally stimulated currents were also present in these materials. On the basis of these observations, the electronic structure of Cu–As–Se is considered from the point of view of localised states.