**4. Conclusion**

The problem of modifying the structural properties of the SnOx films by treatment in glow discharge plasma is studied. Treatments by hydrogen and oxygen plasma permit significantly improve the transparency and gas sensitivity of the SnOx films. The conditions of film synthesis were revealed, which allow by sol-gel technique (400ºС, 6 h) to synthesize the SnO2 films with high gas sensitivity, the minimum response time (2 seconds) and the optimum crystallite size (6 nm); by magnetron sputtering (10% of O2 in ArO2 mixture, 2.7 Pa) to deposit the SnO2 films with optimum properties (average grain size ~ 4 nm, the transparency ~ 90%, band gap ~ 4.0 eV, the refractive index ~ 1.8) without annealing.


the same operating temperature. For the films synthesized by magnetron sputtering, at an operating temperature of 270ºC sensitivity is about 45% (Fig. 31, curve 1). Treatment of H-plasma increases the sensitivity to 52% at the same operating temperature, the same treatment on oxygen plasma increases the sensitivity up to 78% with a decrease in operating

Thus, the regularities of the influence of treatment by H- or O-plasma on growth of the gas sensitivity of SnO2 films were established. The plasma treatment of SnO2 films, obtained by the sol-gel technique, does not alter their phase composition, resulting in gas sensitivity growth does not depend on the type of plasma. Treatment by O-plasma of films prepared by magnetron sputtering, leads to a more significant increase in gas sensitivity than by H-

The problem of modifying the structural properties of the SnOx films by treatment in glow discharge plasma is studied. Treatments by hydrogen and oxygen plasma permit significantly improve the transparency and gas sensitivity of the SnOx films. The conditions of film synthesis were revealed, which allow by sol-gel technique (400ºС, 6 h) to synthesize the SnO2 films with high gas sensitivity, the minimum response time (2 seconds) and the optimum crystallite size (6 nm); by magnetron sputtering (10% of O2 in ArO2 mixture, 2.7 Pa) to deposit the SnO2 films with optimum properties (average grain size ~ 4 nm, the transparency ~ 90%, band gap ~ 4.0 eV, the refractive index ~ 1.8) without

1. A method of formation of the cluster structure of film deposited by a way of spreading, and decrease the average SnO2 crystallite size up to 1.5 nm by increasing the concentration of tin ions in the film-forming solution from 0.14 to 0.83 mol/L, was developed. This leads to an increase in film sensitivity to the ethanol vapors on 20% (for 1 mg/L), decrease of response time in half (up to 3 seconds) and to appearance of sensitivity to the presence of micro-amounts of ethanol vapor (~ 0.05 mg/L). If the concentration of tin atoms in solution is low (0.14 mol/L), the SnO2 nanocrystals in film after deposition, drying (100ºС, 2.5 nm) and annealing (400ºС, 5 nm) were

2. The surfaces of films produced by sol-gel technique (centrifugation method) and magnetron sputtering are fine-grained and in the form of large agglomerates, have an average roughness of 0.6 and 3.6 nm, respectively. The maximum sensitivity of films to the vapors of ethanol is observed at temperatures of 230 and 270ºС, the response time is ~ 3 and 16 s, recovery time ~ 70 and ~ 90 s, respectively. The differences may be due to smaller crystallites, higher porosity and the absence of SnO crystallites in the films prepared by sol-gel technique. The treatment by hydrogen plasma of these fine-grained films leads to the formation of large agglomerates. The same treatment by oxygen plasma leads to the disintegration of the granular surface structure and a partial clustering of the film. Isothermal annealing at 400ºC for 3–6 h leads to the formation of a pronounced granular surface structure. Treatment by hydrogen plasma of coarse grained (~ 60−120 nm) films, synthesized by magnetron sputtering, leads to a slight decrease in the size of the agglomerates, whereas the treatment by oxygen plasma leads

to the destruction of the grains and the film clusterization.

temperature to 255ºC (Fig. 31, curves 2 and 3).

plasma, due to the oxidation of SnOx film.

**4. Conclusion** 

annealing.

formed.


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