I. A. Taratyn’s research while affiliated with Belarusian National Technical University and other places

Strict requirements for determining of gases concentration in the working environment it is relevant to develop of semiconductor sensors which provide rapid response and safety of personnel in industrial and domestic premises. The aim of the work was to study gas-sensitive and dynamic characteristics of high-sensitive low-power sensors made on thin nanoporous substrates with gas-sensitive layers of semiconductor metal oxides. The low-power semiconductor gas sensor on the anodic alumina substrate has been developed. Sensors with gas-sensitive semiconductor metal oxide layers based on In 2 O 3 +Ga 2 O 3 , In 2 O 3 +SnO 2 and SnO 2 +Pd deposited from aqueous solutions with subsequent firing on sensor information electrodes are manufactured. Studies of gas-sensitive characteristics have shown that sensors with SnO 2 films with the addition of Pd nanoparticles have maximum sensitivity of about 85 % and high response rate to 10 ppm H 2 at 410 °C. The maximum sensitivity of 250 % to 10 ppm CO at 220 °C was shown by films based on In 2 O 3 +SnO 2 , the response time τ 90 was 5 s, while the sensitivity of In 2 O 3 +Ga 2 O 3 and SnO 2 +Pd was 30–50 % at 410–420 ºC. Semiconducting metal oxides In 2 O 3 +Ga 2 O 3 (70 % at 420 °C) and In 2 O 3 +SnO 2 (30 % at 250 °C) showed lower sensitivity to hydrogen, with response time τ 90 = 20 s. The sensors power consumption in all measurements was 28–60 mW. Semiconductor gas sensors with low energy consumption can be used in the systems development that monitor the carbon monoxide concentration in the work area, as well as detect ignition's early stages.

Monitoring of air pollutions is one of actual trends in the development of industrial and domestic instrumentation. There are sets of tasks for improving gas analytical instruments because of increasing demand for control of a concentration of explosive and toxic gases on a level with maximum allowable concentration. The aim of the paper was to investigate the methods of formation and elemental composition of indium oxide films modified with tin oxide on the surface of gas sensor elements as one of the promising compounds for improving the detection efficiency of explosive and toxic gases in the environment. The processes of formation of gas-sensitive films deposited on the surface of nichrome alloy information electrodes were studied in this article. Substrates of anodic aluminum oxide with area of 10 × 10 mm2 and a thickness of 45 ± 0,5 μm were chosen for research. Two layers on the surface of the samples were formed. The first layer was formed from NiCr alloy (Ni – 80 %, Cr – 20 %) with a thickness of ≈ 0.3 μm by ion-plasma sputtering. The second layer was based on indium oxide with addition of tin oxide with thicknesses from ≈ 0.3 μm to ≈ 1.0 µm and coated with sol-gel technology. Five samples of gas-sensitive films were formed with different methods of deposition and heat treatment. Scanning electron microscopy was used for study of films’ morphology and elemental compositions of samples. The most perfect continuous semiconductor films were obtained by multilayer applying of a sol-gel paste. When semiconductor films were processed at annealing temperatures of 700 °C and higher in vacuum so there was observed cracking of semiconductor films up to a layer of NiCr alloy. The developed surface of gas-sensitive films allows to reach high sensitivity and affectivity of semiconductor sensors for control of air gas composition.

The regularities of changes in the frequencies and forms of natural oscillations and the stress state of a silicon sensing element of a mechanical MEMS accelerometer system depending on changes in the radii of rounding of structural elements are considered. An increase in the natural frequencies of the system and stresses in torsion suspensions has been established with an increase in the radii of the coupling of the suspension with the frame and the inertial mass. The rounding of the shape of the suspensions in the plan leads to a decrease in natural frequencies and an increase in stresses arising from oscillatory movements. The fact of localization of high-frequency oscillation forms in the inertial mass is confirmed. A set of design solutions is recommended to control the vibration state of the MEMS accelerometer mechanical system.

The article discusses the prospects of creating controlled field-effect cathodes based on arrays of columnar oxide niobium nanostructures for field emission displays. Geometrical models of field-emission cathodes and vacuum elements have been developed and investigated. The distribution of the electric field in the vacuum device at various distances between the cathode and the anode, the applied voltages between them, the shape and microgeometry of the cathodes were obtained. The optimal geometric parameters of nanostructured autoelectronic cathodes and matrices of these were calculated based on the simulation. The technological route has been developed for the production of autoelectronic cathode matrices based on arrays of niobium-oxide columnar nanostructures formed by electrochemical anodization of Al/Nb thin-film system. The samples of controlled arrays of autoelectronic cathodes were fabricated and the current-voltage characteristics with interelectrode gap of 2, 5 and 10 μm in various electric modes with change in the electric field strength from 3 to 85 V/μm were studied. At 2 μm gap between the anode and cathode, the emission occurs at minimum threshold voltages, but it is characterized by limited current values. The increasing in the interelectrode gap allows rising the emission currents, however, the threshold voltages increase. In the pulsed mode, the large emission currents are achieved. The threshold voltage of autoelectronic cathode matrices with interelectrode gap of 5 μm was 9.16 V, the maximum currents reached 350 μA at voltage of 22.5 V. In the pulsed mode, the emission arose at 11.06 V, the maximum current reached 1500 μA at 40 V.

Analysis of the world market reveals an increasing need for microelectromechanical transducers of the sensor and actuator type (hereinafter referred to as transducers). One of the ways to improve the operational characteristics of these devices is the development of new functional, in particular, intelligent materials, using a base (substrate) structured at the nanoscale level. This work presents the results of studies of the structure and morphological features of thin films based on C60 polymer forms synthesized by electron beam deposition on the surfaces of nanoporous anodic aluminum oxide and structured polyimide films. Анализ мирового рынка выявляет возрастающую потребность в микроэлектромеханических преобразователях сенсорного и актуаторного типа (далее - преобразователей). Одним из путей повышения эксплуатационных характеристик указанных приборов является разработка новых функциональных, в особенности, интеллектуальных материалов, с использованием основы (подложки), структурированной на наномасштабном уровне. В настоящей работе приведены результаты исследований структуры и морфологических особенностей тонких пленок на основе полимерных форм С60, синтезированных методом электронно-лучевого осаждения на поверхностях нанопористого анодного оксида алюминия и структурированных полиимидных пленок.

Gas-sensitive composition of tungsten oxide, prepared by sol gel method, with multiwall carbon nanotubes was investigated by transmission electron microscopy (TEM), measuring the electrical conductivity and surface area. Micro-power sensors (P ≤ 85 mW), containing WO3 ‑MWCNT as a sensing element were manufactured and tested. The greatest sensitivity to propane (≤ 400 %) was observed at substrate temperature below 200 ºC, while appreciable sensitivity to NO2 (≥ 300 %) was observed at higher temperatures (T ≈ 240 ºC or higher). Adding MWCNTs has no significant effect on sensitivity to hydrogen around the temperature range studied (current heating 21–75 mA). Gas sensor’s sensitivity to NO2 in a certain operating temperature range are more than 1000 %. The investigated gas-sensitive composition of tungsten oxide with MWCNTs is suitable for creating highly sensitive semiconductor sensors for combustible gases and nitrogen dioxide (including equipments for environmental air monitoring). The sensors have a high-speed response and recovery, and low power consumption.