Please use this identifier to cite or link to this item: http://cris.utm.md/handle/5014/636
Title: Surface Phenomena in Glassy Chalcogenides by Gas Sensing
Authors: TIULEANU, Dumitru 
CIOBANU, M. 
MOCREAC, Olga 
Keywords: Surface phenomena;Chalcogenide films;Gas sensors
Issue Date: 30-Jul-2020
Source: Tsiulyanu D., Ciobanu M., Mocreac O. (2020) Surface Phenomena in Glassy Chalcogenides by Gas Sensing. In: Petkov P., Achour M., Popov C. (eds) Nanoscience and Nanotechnology in Security and Protection against CBRN Threats. NATO Science for Peace and Security Series B: Physics and Biophysics. Springer, Dordrecht. https://doi.org/10.1007/978-94-024-2018-0_25
Project: 15.817.02.29A. Multifunctional nanomaterials and nanoelectronic devices based on nitrides, oxides and chalcogenides for biomedicine / Nanomateriale multifuncţionale şi dispozitive nanoelectronice în bază de nitruri, oxizi şi calcogenuri pentru biomedicină 
20.80009.5007.21. Calcogenuri sticloase cu reţele spaţiale autoorganizate pentru bioinginerie 
Journal: NATO Science for Peace and Security Series B: Physics and Biophysics
Abstract: 
The surface phenomena in glassy chalcogenides (GCh), including those caused by gas adsorption, are reviewed and discussed. A detailed quantitative analysis is made on experimental data taken on glassy and nanocrystalline chalcogenide based thin films of As2S3Ge8 – Te system, physically grown in vacuum. Particularly the measurements of the frequency dependence of the AC conductivity of these films in the frequency range 5 Hz–13 MHz are reported, in both dry air and its mixture with a controlled concentration of different gases. The behavior of AC conductivity fits the generally accepted model of charge transport in disordered materials that implies both the extended states above mobility edges and the localized states in the gap, but the variation of the environmental conditions by applying of even very small amount (ppm) of toxic gases, dramatically influences the AC conductivity spectra. This is evidence that for some chalcogenide materials the surface phenomena disturb the energetic distribution of the states adjacent to the surface leading to modifications of the transport mechanisms by the surface. The modification of the surface transport mechanism by adsorption of gas species alters the physical parameters of the surface, i.e. the work function, the diffusion and the dipolar potential, the screening length, etc., which lead to variation of both surface and total electrical conductivity, impedance and its spectral distribution, as well as of electric capacity of functional structures based on these materials. The examples are given of the development of room temperature operating functional structures designed to detect nitrogen dioxide and hydrogen sulfide in dry and humid media via variation of their impedance or capacitance.
URI: http://cris.utm.md/handle/5014/636
ISBN: 978-94-024-2044-9
978-94-024-2018-0
DOI: 10.1007/978-94-024-2018-0_25
Appears in Collections:Book/Monograph Contributions

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