Quenching of photodarkening in metal-doped chalcogenide amorphous films

Photodarkening relaxation under light exposure of a-As₄₀Se₆₀ amorphous films doped with 0.5 at.% of metals Sn, Mn, Sm, Pr or Dy and a-As₅₀Se₅₀ films doped up to 10.0 at.% Sn were studied for their dependence on the type and concentration of impurities and thermal treatment. Both factors reduce photodarkening with the degree of reduction dependent on the type and concentration of impurity. The relaxation process may be described by a stretched exponential with the dispersion parameter 0.4≤α<0.9 and the time constant increasing with impurity concentration or thermal annealing. The results are discussed in context of the "slip-motion" model of photodarkening in chalcogenide glasses.