Impact of Adsorbed Gases on the Transport Mechanisms in Ge 8 As 2 Te 13 S 3 Amorphous Films
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TSIULYANU , Dumitru; CIOBANU, Marina. Impact of Adsorbed Gases on the Transport Mechanisms in Ge 8 As 2 Te 13 S 3 Amorphous Films. In: Glass Physics and Chemistry. 2019, nr. 1(45), pp. 53-59. ISSN 1087-6596.
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Glass Physics and Chemistry
Numărul 1(45) / 2019 / ISSN 1087-6596

Impact of Adsorbed Gases on the Transport Mechanisms in Ge 8 As 2 Te 13 S 3 Amorphous Films


DOI: 10.1134/S1087659619010140
Pag. 53-59

Tsiulyanu Dumitru, Ciobanu Marina
 
Technical University of Moldova
 
Disponibil în IBN: 6 iunie 2019


Rezumat

Abstract: It is shown that the gas adsorption in chalcogenide glasses results in modifications of transport mechanisms by the surface, along with formation of surface localized states. A detailed quantitative analysis is made on experimental data taking on glassy thin films of Ge 8 As 2 Te 13 S 3 , physically grown in vacuum. The measurements of alternating current (AC) conductivity of these films have been carried out in the frequency range from 5 Hz to 13 MHz, in both dry air and its mixture with a controlled concentration of nitrogen dioxide, at different temperatures. It was found that the changes of environmental conditions by applying of even very small (ppm) amounts of toxic gases, e.g. NO 2 , dramatically influences the AC conductivity spectra. This is due to a sharp increasing of holes concentration in the valence band of an ultrathin layer adjacent to surface, which results in modification of the dominant mechanism of current flow. In a definite frequency range the charge transport by hopping via valence band edge localized states becomes negligible and the mechanism of conductivity via extended states becomes the main until frequencies ω > 10 5 Hz, at which the mechanism of hopping via localized states in the vicinity of Fermi level becomes predominant.

Cuvinte-cheie
amorphous chalcogenides, charge transport, Gas adsorption, NO2