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The electrical conductivity in chalcogenide glasses is found to obey the Meyer–Neldel rule,σ=σ00eΔE/EMNe−ΔE/kT. The Meyer–Neldel characteristic energy, EMN, lies in the range 25–60 meV with σ00 in the range 10−5–10−15 S cm-1 which seems to be too small for band transport. A surprising correlation between σ00and EMN is also found.

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We have modeled the photoinduced volume change in amorphous selenium. After photon absorption, we treated the excited electron and hole independently within the framework of the tight-binding formalism. We found covalent bond breaking in amorphous networks with photoinduced excited electrons, whereas excited holes contribute to the formation of interchain bonds. We also observed a correlated volume change of the amorphous samples. Our results provide a new and universal description, which can simultaneously explain the photoinduced volume expansion and shrinkage. This model is supported by very recent in situ surface height measurements for amorphous selenium.

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