Presentation is loading. Please wait.

Presentation is loading. Please wait.

Examination of mechanical stability and gas sensor application of (As 2 S 3 ) 100-x (AgI) x chalcogenide glasses K. Kolev 1 *, T. Petkova 1, C. Popov 2.

Similar presentations


Presentation on theme: "Examination of mechanical stability and gas sensor application of (As 2 S 3 ) 100-x (AgI) x chalcogenide glasses K. Kolev 1 *, T. Petkova 1, C. Popov 2."— Presentation transcript:

1 Examination of mechanical stability and gas sensor application of (As 2 S 3 ) 100-x (AgI) x chalcogenide glasses K. Kolev 1 *, T. Petkova 1, C. Popov 2 1 Institute of Electrochemistry and Energy Systems (IEES), Bulgarian Academy of Sciences 2 Institute of Nanostructure Technologies and Analytics (INA), University of Kassel, Germany INAINA EXPERIMENTAL SET–UP SORPTION PROPERTIES CONCLUSIONS The surface and morphology analysis of the thin films shows that films are uniform, homogeneous, featureless and smooth both on surface and in depth The magnitude and the sign of the stress are functions of the film composition and structure as well as of the mechanical and thermomechanical properties. The bigger tensile stress of the samples with 5 % at. AgI can be related to initial incorporation of atoms with larger atomic radius into As 2 S 3 pyramidal structure. As AgI amount increases Ag atoms occupy the microvoids and thus the glass density enhances and the structure stabilizes. This densification and stabilization of the structure leads to weakening of the tensile stress and change in the sign of the mechanical stress to compressive in the samples with 25 and 30 % at. of AgI. Resonating cantilevers functionalized with amorphous (As 2 S 3 ) 90 (AgI) 10 film were exposed to vapors of different analytes, including water, VOC and ammonia, in order to study the sorption properties of the chalcogenide coating. The highest sensitivity was observed towards acetone, the analyte with one of the highest molecular weight and with the lowest dipole moment among the tested analytes. The sensor acted primarily as a microbalance distinguishing the vapors by the difference in their molecular weight with physisorption as main mechanism. The short response and recovery times together with the linear increase of the response signals with the analyte concentration make the investigated As-S-Ag films a promising candidate for gas sensitive elements. MOTIVATION  Development of new transduction principles in the sensoric technique  Search for new sensitive materials  New sensors with improved sensitivity, selectivity and reliability Different functionalization layers for diverse gases Electronic Sensor  Cantilever sensors – a miniature version of a microbalance  Fabrication process – complementary metal-oxide- semiconductor (CMOS) technology  Integration of transducer, actuator and read-out in one unit  Decrease of the resonance frequency with addition of mass, i.e. by sorption of gas molecules CANTILEVER–BASED CHEMICAL GAS SENSORS  K – spring constant of the cantilever  1 – resonance frequency before exposure  2 – resonance frequency after exposure ACKNOWLEDGMENTS The authors gratefully acknowledge the financial support of the European Social Fund (Program “Development of human resources”) under contract BG051PO001/07/3.3-02/58/17.06.2008). Stoney's equation:  - film stress d - film thickness E Si - Young's modulus of the substrate - Poisson's ratio of the substrate D - thickness of the substrate R - curvature radius of the bending L, h - length and deflection of the cantilever beam d R D E Si 1 ) 1 ( 6 2    R L2L2 h2h2   2 h D D cant L d h cantilever, deflection determined by optical microscopy Focus on frameFocus on beam THEORETICAL BASIS of STRESS INVESTIGATION SURFACE and MORPHOLOGYSTRESS MEASUREMENTS


Download ppt "Examination of mechanical stability and gas sensor application of (As 2 S 3 ) 100-x (AgI) x chalcogenide glasses K. Kolev 1 *, T. Petkova 1, C. Popov 2."

Similar presentations


Ads by Google