ПОЛУПРОВОДНИКОВЫЕ ДАТЧИКИ ДИОКСИДА АЗОТА НА ОСНОВЕ КОМПОЗИЦИИ In2O3–Ga2O3–WO3
The properties of oxide gas sensitive compositions In2O3–Ga2O3–WO3 prepared by sol-gel method, with tungsten oxide 5 % wt., gallium oxide 4 % wt., have been investigated. Tungsten oxide addition was established to lead to significant increase in nitrogen dioxide sensitivity. The composition structural features were studied by X-ray diffraction analysis and Raman spectroscopy. It was found that thermal treatment of mixed sols In2O3, Ga2O3, WO3 leads to the formation of hete- rogeneous two-phase material containing (In, Ga)2O3 solid solution and monoclinic WO3 phases. According to X-ray diffraction data, the growth in size of WO3 and In2O3 grains during heat treatment in the mixed In2O3–WO3 composition decelerates as compared to individual oxides. It is assumed that significant increase in the sensitivity to low concentrations of nitrogen dioxide of the composition containing WO3 additive, as compared to the initial one, may be due to the presence of multiply charged adsorption centers (W4+, W5+, W6+), as well as due to the complication (according to EPR) of the defect structure of the double In2O3–WO3 and a triple In2O3–Ga2O3–WO3 composition as compared to the initial oxides. Single-electrode semiconductor nitrogen dioxide sensors with a low threshold of detection (<< 1 ppm) and low power consumption are fabrica- ted. The response of gas sensors based on the In2O3–Ga2O3 (4 % wt.)–WO3 (5 % wt.) composition to gas mixtures containing 10 ppm of NO2 in air has a pronounced maximum at powers of 80–90 mW.