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The optical constants and average thickness of metal - chalcogenide glass films of chemical composition , with x = 5, 10 and 15 at.%, are very accurately determined by a novel method, based only on the transmission spectra at normal incidence, measured over the 400 - 2200 nm spectral range. This useful optical method takes into consideration the non-uniform thickness of the thermally evaporated films (if not corrected, this may lead to too-large calculated values of the absorption coefficient, as well as serious errors in the values of the refractive index and film thickness). The dispersion of the refractive index is discussed in terms of the single-oscillator Wemple and DiDomenico model. The optical-absorption edges are described using the non-direct transition model proposed by Tauc and the optical energy gaps are calculated by Tauc's extrapolation. It has been found that the value of the refractive index increases clearly with copper content, whereas the optical band gap decreases from 1.80 to 1.64 eV.

The static and dynamic current-voltage characteristics of the bulk metal chalcogenide glassy semiconductor Cu 10 (AsSe 1.4 I 0.2 ) 90 have been measured in the temperature range 303-373 K. They exhibit a transition from an ohmic behaviour in the low-field region to a non-ohmic behaviour in the high-field preswitching region, which is explained in terms of the theory of space charge limited conduction. It has found that this glass exhibits a current-controlled negative resistance switching characteristic with memory. The electrical resistance obeys an Arrhenius-type dependence on the ambient temperature with single activation energy E σ in the considered temperature range. The threshold voltage decreases exponentially with increasing temperature and increases as d 1/2 with an increase in the thickness of the investigated samples. The calculated ratio E th / E σ = 0.469 (where E th is the threshold voltage activation energy) is very close to 0.5, obtained theoretically on the basis of electrothermal model. Therefore, the switching phenomenon in the investigated glassy semiconductor can be explained according to a physical model based on the electrothermal breakdown theory.

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