|Conţinutul numărului revistei|
| SM ISO690:2012|
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.
|Glass Physics and Chemistry|
|Numărul 1(45) / 2019 / ISSN 1087-6596|
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.
amorphous chalcogenides, charge transport, Gas adsorption, NO2