Does the charged defect exist in nano-structured oxy-chalcogenide glass?

Photoluminescence and electron-spin resonance in nano-structured GeO ₂-GeS₂ glasses have been studied. With an increase in the GeO₂ content from 0 to 80 mol %, a luminescence peak blue-shifts from 1.3 to 2.1 eV in photon energy, which is more prominent than an increase in the optical gap from 3.4 to 3.6 eV. Dark and photoinduced electron-spin signals become maximal at around an intermediate composition 50GeO₂- 50GeS₂. It is difficult to interpret these composition variations using the charged defect model proposed for chalcogenide glasses.