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Identifier

000401513

Title

Surface acoustic wave devices for gas sensing applications

Alternative Title

Ανίχνευση αερίων με τη μέθοδο ακουστικών κυμάτων επιφάνειας

Author

Μοσχόβης, Κωνσταντίνος

Thesis advisor

Κυριακίδης, Γεώργιος

Reviewer

Αναστασιάδης, Σπύρος
Τζανετάκης, Παναγιώτης

Abstract

The scope of this work lies on the implementation of a sensing technique for detecting minute hazardous gas concentrations, in the parts-per-billion (ppb) range, with high sensitivity, high repeatability, low response speed, and close to room temperature RT conditions, utilizing metal-oxide thin films as active layers on top of Surface Acoustic Wave (SAW) structures and devices. Regarding gas sensing employing surface acoustic waves, the main sensing mechanism lies on the active layer’s conductivity variations towards either reducing or oxidizing gases which in turn are being transformed to acoustic wave velocity changes and consequently to centre frequency shifts of the transmitted wave. In₂O_3-x and ZnO were the two metal-oxide candidates employed as active layers for gas sensing on top of SAW structures and devices. These materials were deposited mainly via two methods. Aerosol Spray Pyrolysis (home-made device apparatus) and DC Magnetron Sputtering were the two techniques used for depositing ZnO while DC Magnetron Sputtering was used for depositing In₂O_3-x. Comparable study on structural, morphological, optical, and electrical as well as preliminary conductometric measurements of these films towards extremely low ozone concentrations allowed for the proper material selection along with its optimum deposition parameters. Upon achieving detection of extremely low ozone concentrations through conventional conductometric techniques, In₂O_3-x thin films have been deposited on top of layered SAW structures and commercial SAW filters operating at various centre frequencies. Finally, sensitivity measurements have been carried out towards different gas concentrations, at various temperatures utilizing a home-made setup.

Language

English

Subject

Gas sensors

Metal Oxides

Thin Films

Αισθητήρες αερίων

Ακουστικά κύματα επιφάνειας

Λεπτά υμένια

Οξείδια μετάλλων

Issue date

2016-06-13