Sensitivity to Ethanol Vapour of Thin Films SnO2 Doped with Fluorine

Abstract

Tin dioxide thin films were obtained by centrifuging. Annealing of samples was carried out in a muffle furnace at a temperature of 400 °C for 15 min, 3, 6 and 12 h. The surface resistance of the films was measured by four-force method. The sensitivity to ethanol vapour was determined by experimental setup that allows measurements in the range from room temperature to 300 °C. There is a change in the acidity of the solution with the addition of ammonium fluoride. To take into consideration this change in acidity, three batches of solutions were prepared: one example without additives, another one ‒ with the addition of ammonium fluoride and the last one ‒ with the addition of ammonium hydroxide. Films synthesized from a film-forming solution containing NH4F have less resistance than films obtained from solutions that do not contain ammonium fluoride. This confirms the presence of fluorine ions in the films as additional sources of free charge carriers. It is found that the pH-indicator of the film-forming solution does not affect the surface resistance of the synthesized SnO2 films. Annealing of fluoride doped films leads to an increase in surface resistance by two orders of magnitude, which is associated with the removal of fluorine from the films and the formation of a large number of defects. Further annealing leads to a decrease in surface resistance, which seems to be associated with a decrease in defects. It is shown that the change in the hydrogen index of the film-forming solution leads to the formation of films with a thermally stable sensitivity to ethanol vapour.

Influence of Annealing Time on the Optical and Electrical Properties of Tin Dioxide-Based Coatings

“…It is a semiconductor material with a unique characteristic of high optical transparency in the visible range of electromagnetic radiation and low electrical resistance [3,4]. Tin dioxide has numerous applications, serving as a gas-trapping layer in various gas sensors [5,6], an effective photoanode [7,8], a protective coating against corrosion [9,10], an antibacterial coating [11,12], an anode for high-performance lithium-ion batteries [13,14] and for various other purposes. Tin dioxide also has medical applications, such as serving as a glucose sensor [15,16].…”

The Influence of Lyophobicity and Lyophilicity of Film-Forming Systems on the Properties of Tin Oxide Films

“…SnO 2 thin films possess exceptional properties, including a wide bandgap (Eg = 3.6 eV), n-type conductivity, transparency of more than 80% in the visible wavelength range, chemical stability, and others [1][2][3]. As a result, SnO 2 has been widely used in various applications such as solar cells [4][5][6], gas sensors [7][8][9], transistors [10][11][12], optoelectronic devices, and transparent conductive electrodes [13][14][15]. SnO 2 films are doped and modified in composition to meet the increasing demand for functional coatings.…”

The effect of three-minute exposure of oxygen plasma on the properties of tin oxide films

“…This ability makes it possible to use SnO 2 as a catalyst for oxidative processes [5][6][7]. The change in the resistance of tin oxide in the presence of various gases formed the basis for use as a sensitive element in gas sensors [8][9][10].…”