Combined configuration-enthalpy model describing radiation-optical responses in chalcogenide semiconductor glasses

Combined configuration-enthalpy model evolving free energy configuration-coordinate and thermodynamic enthalpy diagrams is developed to describe the phenomenology of optical responses in structural metastability of chalcogenide semiconductor glasses of As-S system activated under prolonged physical ageing and high-energy γ-irradiation. The developed approach foresees glass stabilization in ground-state multibasin formed by rejuvenation-induced, irradiation-induced and/or most stable annealing-induced basins, interlinked by thermally-activated over-barrier jumping and through-barrier tunneling transitions. Effect of high-energy γ-irradiation in glasses is described due to vertical transitions of atomic sites into excited state followed by non-radiative relaxation into irradiation-induced glass ground state. This approach based on interlinked enthalpic and configuration-coordinate diagrams allows complete parameterization of optical responses related to induced metastable states, defined in blue (bleaching) or red (darkening) shifts in the transmission spectra of As-S glasses detected in the region of their fundamental optical absorption edge.