Study of the sorption properties of Ge20Se80 thin films for NO2 gas sensing

Chen, Ping; Mitkova, M.; Ténné, D. A.; Wolf, Kasandra; Георгиева, В.; Vergov, L.

doi:10.1016/j.tsf.2012.09.077

Cited by 11 publications

(11 citation statements)

References 37 publications

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“…The ratios of the contribution from Ge-Se or Ge-O bonds are labeled in the figure. In Ge 3d core level XPS spectra, unlike the previously reported results in [3], we saw a slight decrease of Ge-O bonds after gas sorption. This suggests that the film was not subject to additional oxidation by NO 2 gas and gas sorption is pure physical.…”

Section: Resultscontrasting

confidence: 88%

“…The relatively big voids will not interact with absorbed NO 2 molecules as strongly as previously reported in Ge 20 Se 80 glass [3] where the molar volume is much smaller and very tight contact between the NO 2 molecules and the Ge-Se backbone occurs. Our studies of the sorption effects of NO 2 in the Ge-Se system suggest a strong compositional dependence on this process which is in essence related to the structure of the glass.…”

Section: Discussionsupporting

confidence: 66%

“…For a fast and effective sorption of NO 2 , a large free volume and a very open structure are desirable. One initial idea about the ability of the studied glasses to sorb gas molecules can come from their molar volume [18] and packing fraction [3] presented in Fig. 9.…”

Section: Discussionmentioning

confidence: 99%

“…Experiments show that Ge stabilizes the structure, durability and stability of the pure chalcogen films towards oxidation [6]. The Ge 33 Se 67 glasses have one of the lowest packing density among the chalcogenide glasses [3] and hence, there are chances for a good sorption ability of NO 2 in them.…”

Section: Introductionmentioning

confidence: 99%

“…It has a very high molar volume of 20.46 cm 3 /mol and thus, compared to other chalcogenide glasses [3] offers substantial potential for application in gas sensors. It shows a relatively good sorption which is governed by its two-dimensional structure that is accomplished by hexagonal chains.…”

Section: Introductionmentioning

confidence: 99%

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NO2 gas sorption studies of Ge33Se67 films using quartz crystal microbalance

Георгиева

Mitkova

Ténné

et al. 2012

Materials Chemistry and Physics

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A study on the NO 2 gas sorption ability of amorphous Ge 33 Se 67 coated quartz crystal microbalance (QCM) is presented. The thin films have been characterized before and after sorption/desorption processes of NO 2 by energy-dispersive X-ray spectroscopy (EDS), grazing angle X-ray diffraction (GAXRD), Raman spectroscopy, X-ray photoelectron spectroscopy (XPS) and atom force microscopy (AFM) measurements. These studies indicated that physisorption occurs when NO 2 gas molecules are introduced into the chalcogenide film and the thin film composition or structure do not change. The mass loading due to NO 2 gas sorption was calculated by the resonator's frequency shift. At the conditions of our experiment, up to 6.8 ng of the gas was sorbed into 200nm thick Ge 33 Se 67 film at 5000 ppm NO 2 concentration. It has been established that the process of gas molecules sorption is reversible.Keywords: Chalcogenides; Thin films; X-ray photo-emission spectroscopy (XPS); Atomic force microscopy (AFM).

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Section: Resultscontrasting

confidence: 88%

Section: Discussionsupporting

confidence: 66%

Section: Discussionmentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

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NO2 gas sorption studies of Ge33Se67 films using quartz crystal microbalance

Георгиева

Mitkova

Ténné

et al. 2012

Materials Chemistry and Physics

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X‐ray radiation induced effects in selected chalcogenide glasses and CBRAM devices based on them

Mitkova

Wolf

Belev

et al. 2015

Physica Status Solidi (b)

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Conductive bridge resistance change (CBRAM) memory devices are one of the premier emerging technologies for nonvolatile memory. The application of these devices could overlap possible situations where they are expected to perform in environments containing X-ray radiation. This poses the question, how X-ray radiation affects the materials comprised within these devices, as well as the performance of the CBRAM devices. In this work, we studied the structural changes caused by a wide range X-ray radiation over thin Ge-Se films with composition ranging from Se rich to Ge rich, as well as X-ray induced Ag diffusion within these films. The results show that after the cessation of radiation, the Ge rich films undergo considerable structural modification while the other compositions did not exhibit substantial changes. X-ray stimulated Ag diffusion with formation of Ag-Se by-products occurred predominantly in the Se and Ge rich films. These effects influence the performance of the CBRAM devices, based on these films and their I-V characteristics, threshold voltage and endurance are presented and discussed in the context of the materials characterization findings of this work, performed by Raman spectroscopy, Energy dispersion spectroscopy and X-ray diffraction. 1 Introduction The photoinduced effects in chalcogenide glasses (ChG) induced by exposure to visible and UV light are studied in depth and are well documented [1,2]. Similarly to visible light, X-rays can have indirectly ionizing effects on chalcogenide glass films. However, due to the shorter wavelength, the energy of the X-rays will be very high, leading to unique structural changes [3]. This for example, opens the opportunity for applying the effect of interaction of X-rays with chalcogenide glasses for the formation of X-ray flat panel image detectors [4,5]. Their performance is based on the absorption of X-ray photons by the chalcogenide photoconductor (usually a-Se) which facilitates the direct conversion of X-ray photons to electric charges. The studies, performed in relation with these X-ray induced effects of photocurrent in the chalcogenide films, resulted in the establishment of a charge trapping model for

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Short-range order of germanium selenide glass

Moharram

2015

Bull Mater Sci

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Chalcogenide Ge 20 Se 80 glass was prepared using the melt-quench technique. The radial distribution function is obtained from X-ray diffraction data in the scattering vector interval 0.28≤K≤ 6.87 Å −1. Reverse Monte Carlo (RMC) simulations are useful to compute the partial pair distribution functions, g ij (r), partial structure factors, S ij (K), and total structure factor. Values of r 1 /r 2 ratio and bond angle () indicate that Ge(Se 1/2) 4 tetrahedra units connected by chains of the chalcogen atoms are present. The partial structure factors have shown that homopolar Ge-Ge and Se-Se bonds are behind the appearance of the first sharp diffraction peak (FSDP) in the total structure factor. Tetrahedral Ge(Se 1/2) 4 structural units connected by Se-Se chains have been confirmed by the simulated values of the partial coordination numbers and bond angle distributions. Finally, Raman spectra measurements have strongly supported the conclusions obtained either from the calculated Fourier data or from RMC simulations.

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Study of the sorption properties of Ge20Se80 thin films for NO2 gas sensing

Cited by 11 publications

References 37 publications

NO2 gas sorption studies of Ge33Se67 films using quartz crystal microbalance

NO2 gas sorption studies of Ge33Se67 films using quartz crystal microbalance

X‐ray radiation induced effects in selected chalcogenide glasses and CBRAM devices based on them

Short-range order of germanium selenide glass

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