Study of quartz crystal microbalance NO2 sensor coated with sputtered indium tin oxide film

18th International School on Condensed Matter Physics: "Challenges of Nanoscale Science: Theory, Materials, Applications"

Georgieva, V.^1 ; Aleksandrova, M.^2 ; Stefanov, P.^3 ; Grechnikov, A.^4 ; Gadjanova, V.^1 ; Dilova, T.^3 ; Angelov, Ts^1

Georgi Nadjakov Institute of Solid State Physics, Bulgarian Academy of Sciences, Tzarigradsko Chausse Blvd. 72, Sofia

1784, Bulgaria^1

Technical University of Sofia, Department of Microelectronics, Kliment Ohridski blvd, No 8, bl. 1, Sofia

1000, Bulgaria^2

Institute of General and Inorganic Chemistry, Bulgarian Academy of Sciences, Acad. Georgi Bonchev str.bl. 11, Sofia

1113, Bulgaria^3

Vernadsky Institute of Geochemistry and Analytical Chemistry of RAS, Kosygin str. 19, Moscow

119991, Russia^4

关键词: Ellipsometric method;    Frequency shift;    Gas molecules;    Indium tin oxide;    Indium Tin Oxide films;    Rf-sputtering;    Sauerbrey equation;    Sorption process;   

Others  :  https://iopscience.iop.org/article/10.1088/1742-6596/558/1/012037/pdf
DOI  :  10.1088/1742-6596/558/1/012037

来源: IOP

【 摘 要 】

A study of NO2gas sorption ability of thin indium tin oxide (ITO) deposited on 16 MHz quartz crystal microbalance (QCM) is presented. ITO films are grown by RF sputtering of indium/tin target with weight proportion 95:5 in oxygen environment. The ITO films have been characterized by X-ray photoelectron spectroscopy measurements. The ITO surface composition in atomic % is defined to be: In-40.6%, Sn-4.3% and O-55%. The thickness and refractive index of the films are determined by ellipsometric method. The frequency shift of QCM-ITO is measured at different NO2concentrations. The QCM-ITO system becomes sensitive at NO2concentration ≥ 500 ppm. The sorbed mass for each concentration is calculated according the Sauerbrey equation. The results indicated that the 1.09 ng of the gas is sorbed into 150 nm thick ITO film at 500 ppm NO2concentration. When the NO2concentration increases 10 times the calculated loaded mass is 5.46 ng. The sorption process of the gas molecules is defined as reversible. The velocity of sorbtion /desorption processes are studied, too. The QCM coated with thin ITO films can be successfully used as gas sensors for detecting NO2in the air at room temperature.