Meyer–Neldel DC conduction in chalcogenide glasses

Meyer–Neldel (MN) formula for DC conductivity (σDC) of chalcogenide glasses is obtained using extended pair model and random free energy barriers. The integral equations for DC hopping conductivity and external conductance are solved by iterative procedure. It is found that MN energy (ΔEMN) originates from temperature-induced configurational and electronic disorders. Single polaron-correlated barrier hopping model is used to calculate σDC and the experimental data of Se, As2S3, As2Se3 and As2Te3 are explained. The variation of attempt frequency ν0 and ΔEMN with parameter (r/a), where r is the intersite separation and a is the radius of localized states, is also studied. It is found that ν0 and ΔEMN decrease with increase of (r/a), and ΔEMN may not be present for low density of defects.