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.
In this paper, we propose a method that makes it possible to use an ultrathin calorimeter for direct measurements of cosmic rays with energies of TeV and higher. The problems of determining the primary energy with a thin calorimeter, due to large fluctuations in shower development, the low statistics of analyzed events and the large size required for the calorimeter, are considered in detail. A solution to these problems is proposed on the basis of a lessening fluctuation method. This method is based on the assumption of the universality of the development of cascades initiated by particles of the same energy and mass. For energy reconstruction, so-called correlation curves are used. The main analyzed quantities are the size of the cascade and the rate of its development. The method was tested using the calorimeter of the PAMELA collaboration. Based on simulations, it is shown that the primary energy can be determined on the ascending branch of the cascade curve. This fact solves the problems associated with the need to increase the calorimeter thickness with an increase in primary energy and with the limitation of the analyzed events. The proposed technique is universal for different energies and different nuclei.
This work presents a method for background removal and signal-to-noise ratio enhancement by an accumulation of signal and noise along analyzed spectrum. In this case, the signals are accumulated, and noise, due to its chaotic nature, is suppressed. The method is applied to analyze spectra obtained on DRON-6 diffractometer for study of the crystal structure of thin tin dioxide films produced by sol–gel technology and deposited on a glass substrate. The standard analysis of the crystallographic planes of the samples under study is practically impossible due to the high noise level and the negative influence of the background from the glass substrate. The proposed method transformed the initial spectrum, which cannot be analyzed, into an informative spectrum: the background signal from the substrate is correctly subtracted and the noise decreases by 10 times. To check for possible signal distortion due to accumulation signal along the spectrum, an analysis of simulated spectra was carried out. The onset of the transition of an amorphous state to a crystalline structure of SnO2 is investigated. The crystalline structure of SnO2 thin films depending on the annealing temperature is studied.
This paper considers the effect of oxygen and hydrogen plasma on SnO2 films synthesized from solutions of tin tetrachloride containing NH4F and NH4OH additives. It was found that the treatment of samples with oxygen plasma for 5 min led to a decrease in transparency by 1.11 and 1.17 times. On the transmission spectra, a decrease in the transmittance at a wavelength of 450 nm to 38.1% (1.24 times) in samples obtained from solutions with the addition of NH4F and up to 29.9% (1.53 times) in samples obtained from solutions with the addition of NH4OH is observed. The formation of tin oxide (II) under the influence of the reducing properties of hydrogen plasma is assumed. At the same time, the formation of metal tin from tin dioxide is not observed here. Due to the decreasing of transmission coefficient in the long-wave region of the spectrum. There is an increase in surface resistance after treatment with oxygen plasma, due to filling oxygen vacancies. Treatment of hydrogen plasma films leads to a decrease in surface resistance. Perhaps due to the increase in oxygen vacancies under the influence of hydrogen plasma. Within five minutes, the oxygen and hydrogen plasma had a more active effect on the films obtained from the solution with the addition of ammonium hydroxide, which is associated with a higher porosity of the sample. Consequently, irrespective of the time of plasma exposure with increasing the surface of contact between ionized gases and the film material, the interaction efficiency will increase.
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